Chest computed tomography (CT) image quality impacts radiologists’ diagnoses. Pre-diagnostic image quality assessment is essential but labor-intensive and may have human limitations . This study aims to develop and validate a deep learning (DL)-driven multi-view multi-task image quality assessment (MThis retrospective study utilizes and analyzes chest CT images from 327 patients. Among them, 1613 images from 286 patients are used for model training and validation, while the remaining 41 patients are reserved as an additional test set for conducting ablation studies, comparative studies, and observer studies. The MIn the additional test set, the MThis study develops and validates a DL-driven M Computed tomography (CT) is commonly performed in the diagnostic radiographic examination. The image quality of chest CT affects the diagnostic decision of radiologists , 2, whicCT scan will cause a certain amount of radiation to the patient; high-dose radiation is detrimental to health . RadioloThe artifact in the CT image is one of the factors affecting the image quality, and caused not only by the inappropriate movement  of the patient but also by other external factors . SpecifiIQA is an effective approach to assess the quality of perceived visual stimuli and fall into two categories: subjective assessment by human and objective assessment by algorithms designed to mimic the subjective judgment . SubjectIn recent years, deep learning (DL) algorithms have been more and more widely used in many fields –25. In tAs a summary, most studies have primarily addressed IQA in chest radiographs, with limited exploration in the realm of chest CT image. In addition, there are many factors that affect image quality, and there are even fewer studies on chest CT image IQA comprehensively considering multiple factors. Thus, this study presents a multi-view multi-task image quality assessment method for chest CT image IQA. The proposed method detects and segments the regions of interest (ROIs) on coronal, axial, and sagittal chest CT images, and the proposed four algorithms  are used to mimic the reviewing strategy of radiologists.A multi-view multi-task image quality assessment  are proposed to enhance the accuracy of the inspiration evaluation model. The pixel threshold algorithm is utilized for assessing the tracheal carina, while the neural statistics algorithm is employed for the evaluation of bronchial beams and ribs. The effectiveness of these two algorithms is demonstrated through ablation studies.Two decision algorithms (region measurement and distance measurement), are proposed to further categorize the model’s evaluation results in the position evaluation. The region measurement algorithm is utilized to determine whether the body is positioned at the center of the scan FOV, while the distance measurement algorithm is employed to assess the accuracy of aligning the start and end of the scan baseline. For the position evaluation task, the absence of these two decision algorithms would prevent the model from obtaining normal classification results, highlighting the significance of these two decision algorithms. The performance results of the position evaluation model reflect the effectiveness of these two algorithms.The major contributions of this study are summarized as follows: In this section, the performance of the object detection model (YOLOv8) and the semantic segmentation model (U-Net) used in this study is evaluated. Additionally, ablation studies are conducted to validate the reliability of the proposed MThe results of the ablation studies are presented in Table The experimental results validate our hypothesis that the PT algorithm can address the issue of similar tracheal carina morphology, and the NS algorithm can effectively mimic the assessment paradigm of radiologists.Detailed statistical analysis and discussions regarding these findings will be described in section Due to the relatively simple ROI segmentation requirements in this study, the commonly used U-Net as a semantic segmentation model is sufficient to meet the segmentation needs of the method. However, some ROIs in this experiment, such as bronchial beams and ribs, are difficult to detect. Therefore, multiple object detection models were trained and their performances were compared. It is important to note that, to ensure accuracy, only bounding boxes with an intersection over union (IoU) greater than 0.70 were considered. Table Table Detailed statistical analysis and discussions regarding these findings will be described in section In the observer study, the proposed method was compared with the assessment ability of radiologists on the additional test set and two public datasets  when comparing the assessment ability of the proposed MIt is noteworthy that both manual and computer evaluations are time-consuming. Therefore, comparing the time consumed by the MDetailed statistical analysis and discussions regarding these findings will be described in section This section will conduct statistical analysis and discussion on the experimental results mentioned above. All statistical analyzes were performed on excel  and p-values were obtained by two-tailed t-test, and p < 0.05 was considered a significant difference.The results of the ablation studies showed that the inclusion of PT and NS algorithms improved the performance of the model. However, upon closer analysis, it was observed that the addition of the PT algorithm did not significantly improve the model’s performance in terms of precision, sensitivity, specificity, and F1-score. To better understand the impact of the PT algorithm on the model’s performance, a two-tailed t-test was performed on the evaluation scores obtained by each model, and the p-values are presented in the last column of Table From Table From Table The reasons for such outcomes are likely twofold. On the one hand, it is plausible that CenterNet’s inherent performance may not align well with the evaluation tasks in this study. On the other hand, it could be attributed to the study’s specific methodology aimed at achieving more accurate detection results. This methodology involves considering only bounding boxes with confidence scores exceeding 0.70, which inherently imposes higher precision requirements on each model’s detections. Under these intensified competitive conditions, CenterNet might have struggled, resulting in the appearance of zero values in precision, sensitivity, and F1-score metrics.After conducting comparative experimental evaluations, the final model training time for each evaluation task is presented in Table From Table The three confusion matrices shown in Fig. The above experimental results indicate that when considering all evaluation tasks , for the additional test set, our MThe above experimental results indicate that when considering all evaluation tasks , for the additional test set, our MThe LungCT-Diagnosis and CMB-LCA public datasets were used to validate the above hypothesis. Due to limitations in the public datasets , this experiment assessed only the remaining five evaluation tasks. The experimental results, as shown in Table The features for distinguishing different descriptive indicators are extremely subtle, and MIn this study, a comprehensive MTable While our MIn conclusion, the MThe Institutional Review Board (IRB) of Fujian Putian Hospital in China approved our retrospective study, and the requirement for informed consent was waived.The method was evaluated on a dataset consisting of 1613 images from 286 patients. The images were collected by radiologists at the Fujian Putian Hospital between January 1, 2020, and November 31, 2022. The patients were primarily scanned using two CT scanners: the SIEMENS SOMATOM DEFINITION DUAL SOURCE and the GE LIGHTSPEED. The tube voltage ranged from 120 to 150 kV, and the tube current was controlled using automatic tube current modulation technology, typically ranging from 50 to 800mA. The CT images were acquired with a thin layer thickness for the lung window, ranging from 0.625 to 1 mm.To ensure the quality and diversity of the data used for deep learning tasks, radiologists carefully selected CT images from different scanning planes and considering the desired evaluation criteria. The dataset was divided into two parts. One part was split into three subsets with a ratio of 7:2:1 for training, validation, and testing, respectively, with the testing subset also used for comparative studies. The other part was reserved as an additional test set for the ablation studies and observer studies. It’s worth noting that a portion of both the LungCT-Diagnosis and CMB-LCA public datasets were incorporated into the observer studies, with the aim of validating the robustness and effectiveness of the proposed MIn this section, the proposed method for MTo overcome the limitations of a single-view model, three scanning planes  are used to comprehensively evaluate whether CT examinations produce high-quality images that are suitable for prognosis. As depicted in Fig. All the assessment results are obtained using the object detection model and semantic segmentation model. The object detection model aims to accurately enclose the ROIs with bounding boxes, while the semantic segmentation model aims to accurately segment the ROIs. By leveraging these two deep learning models, a multi-task strategy is proposed to comprehensively consider the information from multiple views and evaluate CT image quality as comprehensively as possible. Additionally, each aspect is assigned a corresponding score, which is then integrated to provide an image quality score for the series of CT images obtained from each patient. The entire evaluation process is end-to-end and automated, aiming to minimize the workload of radiologists and improve screening efficiency.To comprehensively evaluate the adequacy of patient inspiration, three aspects  are considered. the object detection model (YOLOv8) is utilized to obtain ROIs  from a series of CT images. Since CT scanning saves the results of the current scanning position at regular intervals, typically only one CT image in the series contains the most suitable tracheal carina image for evaluation. For tracheal carina evaluation, further segmentation using the semantic segmentation model (U-Net) is performed based on the YOLOv8 detection result to segment the tracheal carina. The final score is derived from the segmentation result. The architecture and implementation of the three sub-parts of the evaluation are illustrated in Fig. It is worth noting that due to the similarity between convex and flat tracheal carina , G, B represents the values of the red, green, and blue channels of the current pixel, respectively.For a pixel, if the values of the red, green, and blue channels simultaneously fall within the range of , the count of white pixels is incremented by one. If the value of the red channel falls within the range of , the count of red pixels is incremented by one. Similarly, if the value of the green channel falls within the range of , the count of green pixels is incremented by one. The threshold-based decision formula can be defined as follows:argmax is a function that returns the parameter with the highest count among the given parameters. C represents the counting function, which calculates the number of pixels corresponding to the given color parameters.Then, the above formula is applied to each pixel in the image, and accumulates the number of white pixels, red pixels, and green pixels separately. The morphology represented by the highest count among these three categories will determine the current morphology of the tracheal carina. The formula is as follows:Since radiologists typically do not rely solely on the morphology of bronchial beams and ribs in a single CT image to get the final result but rather review multiple images repeatedly, this study uses an object detection model (YOLOv8) to mimic the radiologist’s process of searching for ROIs. The model can detect ROIs in multiple images. However, due to the limitations of model accuracy, not all detection results are correct. Therefore, a NS algorithm aims to mimic the cognitive and memory abilities of the human nervous system. In this study, it emulates the process where radiologists find ROIs and store cognitive information in the “memory storage system” of the brain. After reviewing all the images, the final assessment is made based on this information. The calculation process of the NS algorithm is shown in the dashed rectangular box at the bottom of Fig. argmax denotes the function that returns the category with the maximum count, and CategoryCount represents the count of detection boxes for each category.In this study, the clarity of bronchial beams is classified into four categories: visible, fuzzy, double shadow, and curly. Similarly, the clarity of ribs is also classified into four categories: visible, corrugation, double shadow, and multiple shadows. For a series of CT images of a patient, the NS algorithm counts the number of detection boxes for each category and determines the category with the highest count as the final category assessment. The computation formula for the algorithm is as follows:The classification rules mentioned above will be described in detail in Classification rules and scoring criteria.The position evaluation aims to evaluate whether the patient has a proper position based on three aspects: the position of the body within the scanning FOV, accurate alignment of the scan baseline at the beginning and end, and whether the arms are raised above the head. Prior to performing a CT scan, it is necessary to determine the start and end positions of the scan in order to define the scanning range. This helps to avoid unnecessary radiation exposure to additional body areas. By precisely defining the scan range, only the relevant ROI is exposed to radiation, minimizing radiation dose to other parts of the body that are not required for diagnostic purposes. This targeted approach helps in optimizing the scan parameters and reducing potential risks associated with excessive radiation exposure. It is important to ensure that the body does not deviate from the scanning field of view as it can lead to the occurrence of artifacts. When the body is positioned outside the intended scanning area, it may result in incomplete imaging of certain structures, causing truncation artifacts in the final image. Therefore, maintaining proper alignment and positioning of the body within the scanning field of view is crucial to obtain high-quality images and minimize the occurrence of artifacts. In addition, another factor that can contribute to the occurrence of artifacts is when the arms are not raised above the head. During a CT scan, if the arms are positioned incorrectly, such as being placed at the sides of the body, they may cause shadows or streaks in the final image, resulting in artifacts. Therefore, it is important to ensure that the patient’s arms are positioned correctly and raised above the head to minimize the occurrence of such artifacts and ensure image quality.The object detection model (YOLOv8) and the semantic segmentation model (U-Net) are also used to obtain ROIs  from a series of CT images. While U-Net provides segmentation results for the body and lung contours, this alone is insufficient to determine whether the body is positioned at the center of the scanning FOV or to assess the alignment accuracy of the start and end scan baselines. Therefore, the region measurement algorithm is proposed to determine the position of the body within the scanning FOV, and the distance measurement algorithm is proposed to assess the alignment accuracy of the start and end scan baselines. The architecture design and implementation of the three sub-parts of the assessment are illustrated in Fig. Decision algorithms The region measurement algorithm aims to further determine whether the patient’s body is centered within the scanning FOV using the body contour segmentation result obtained from the semantic segmentation model (U-Net). Specifically, after obtaining the body contour segmentation image, the algorithm calculates the center point of the image and draws a circular region with a radius of 50 pixels around that center point. Additionally, the algorithm obtains the center point of the body contour. The dashed box on the right side of Fig. I represents a grayscale image, and  represents the pixel coordinates in the image. If the grayscale value of a pixel is less than the threshold value of 5, the pixel is classified as black. If the grayscale value of a pixel is greater than or equal to the threshold value of 5, the pixel is classified as white. To obtain a better body contour, the first step is to convert the image to grayscale. This conversion removes the color information from the image and represents it in shades of gray. This simplifies the image and reduces the influence of color variations on the subsequent processing steps. After converting the image to grayscale, the next step is to perform binarization. Binarization is the process of converting the grayscale image into a binary image, where each pixel is classified as either black or white based on a certain threshold value. Pixels with intensity values below the threshold are set to black, representing the background, while pixels with intensity values above the threshold are set to white, representing the foreground (body). For the region measurement algorithm, the threshold value is set to 5 and can be formulated as:To determine if a blue point falls within a circle with the green point as its center, the following formulas can be used:The distance measurement algorithm aims to further assess the alignment accuracy of the start and end scan baselines by utilizing both the lung contour segmentation results from the semantic segmentation model (U-Net) and the overlayer from the DICOM file. Specifically, after obtaining the lung contour segmentation image, it is tightly enclosed within a rectangular box, which is then overlaid with the overlayer image. The dashed box at the bottom of Fig. In order to obtain better lung contours, the aforementioned process was applied to the lung contour segmentation image as well. This involves converting the original image to grayscale and then obtaining the binary image. It is worth noting that the threshold for binarization is also set to 5, but in this case, the resulting binary image is represented as D can be either T represents the threshold for decision-making, which is set to 15 in this experiment through empirical study.To assess the alignment accuracy of the start and end scan baselines, it is necessary to measure the distance between the upper edge of the rectangular box and the starting scanning baseline, as well as the distance between the lower edge of the rectangular box and the ending scanning baseline, then the followings formula can be used:Radiation protection evaluation aims to determine whether patients have undergone proper radiation protection based on the wearing of radiation-protective products on their neck and abdomen. Since different parts of the body have varying levels of sensitivity to radiation, it is common practice to have patients wear lead-based radiation-protective products on radiation-sensitive areas such as the thyroid gland and reproductive organs before undergoing a CT scan. Figure Artifact evaluation aims to evaluate whether patients have removed metal jewelry or other objects that could interfere with the quality of the CT scan images prior to the examination. Figure In this section, the multi-view fusion strategy will be elaborated in detail. This study employs a multi-view fusion analysis and evaluation approach utilizing information from three scan planes . Different evaluation tasks utilize different scan planes. For instance, the axial and sagittal planes are predominantly used for inspiration evaluation, the axial and coronal planes for position evaluation, the coronal plane for radiation protection evaluation, and the axial plane for artifact evaluation. Therefore, the multi-view fusion strategy is primarily built upon a multi-task evaluation foundation.Anatomically speaking, the coronal plane divides the human body into front and back portions along its long axis, while the sagittal plane divides the body into left and right portions. The axial plane, on the other hand, divides the body into upper and lower sections from a front-to-back perspective. As organs exhibit distinct features across these three scan planes, a deep learning model extracts task-specific medical image features from these planes to enhance task specificity and robustness.By leveraging the characteristics of the specific medical images from the three scan planes, the deep learning model can better tailor its performance to each evaluation task, thus enhancing its capability to achieve accurate and robust evaluations.Classification rules and scoring criteria For a better qualitative and quantitative analysis of the experimental results, the classification rules and scoring criteria presented in Table The rationale behind these definitions is as follows: the maximum achievable score for the inhalation assessment task is 40 points, and for the overall evaluation task, it is 80 points. In this study, four experienced CT image quality diagnostic physicians were invited to perform blind reading, evaluating the resolution of lesions and major structures in CT images. The image clarity required for clinical diagnosis, where diagnostic reports could be issued, was set as the “acceptable” standard. Hence, image quality scores needed to exceed at least 50% of the total available score for an image to be considered “acceptable”.Implementation details The experiments in this study include ablation, comparison, and observer study. For the proposed MContext)  dataset,Context)  dataset.Data augmentation techniques were employed to address the issue of limited data. Different augmentation methods were applied specifically to different evaluation parts, aiming to obtain more informative training data and improve the model’s robustness. Detailed descriptions of the data augmentation methods are provided in Table Evaluation metrics In our experiments, sensitivity, precision, specificity, and F1-score are used as evaluation metrics to assess the performance of the model. The definitions of these metrics are as follows:


Vitis germplasm. We discuss the scientific progress that led to the new strategies being implemented utilizing state-of-the-art next generation sequencing technologies. Additionally, we attempted to delimit the discussion on the algorithms used in phylogenetic analyses and differentiation of grape varieties. Lastly, the contribution of epigenetics is highlighted to tackle future roadmaps for breeding and exploitation of Vitis germplasm. The latter will remain in the top of the edge for future breeding and cultivation and the molecular tools presented herein, will serve as a reference point in the challenging years to come.The contribution of vine cultivation to human welfare as well as the stimulation of basic social and cultural features of civilization has been great. The wide temporal and regional distribution created a wide array of genetic variants that have been used as propagating material to promote cultivation. Information on the origin and relationships among cultivars is of great interest from a phylogenetics and biotechnology perspective. Fingerprinting and exploration of the complicated genetic background of varieties may contribute to future breeding programs. In this review, we present the most frequently used molecular markers, which have been used on  The most popular markers which have been used are the Simple Sequence Repeats (SSR) and the Single Nucleotide Polymorphisms (SNP)  . Althougms (SNP) . Althougms (SNP) . Furtherms (SNP) .Vitis breeding programs. Despite of the plethora of publications that deal with molecular markers , a soil-borne aphid, destroyed millions of own-rooted vineyards. To keep the cultivation alive, a rootstock survival solution had to be found. A commercial rootstock derived from a native American Vitis species, that co-evolved with the disease of phylloxera, displayed a higher degree of resistance  scattered throughout the genome that make up genomic repetitive regions . They us markers  and tendand 10-6  that may10-6   and the Vitis clones is not always straight forward. When different clonal genotypes were analyzed with a small number of markers, differentiation was unsuccessful  of SSR and SNP used in genetic analyses of Vitis cultivars is given in They also have co-dominant nature  and may 5In addition to the use of SSRs and SNPs, other types of molecular markers have been applied  but are generally laborious, costly, time consuming and difficult to apply in low-skilled laboratories. However, the development of Next Generation Sequencing technologies may assist towards the reliable detection of grape genetic diversity even among clones of the same variety.6Algorithms are utilized to infer the evolutionary connections between a group of organisms or sequences based on molecular or morphological data. The outcome of a phylogenetic analysis is a tree, which displays the putative evolutionary connections among the sequences. The construction of the tree is an essential step in phylogenesis because it is the process of finding the tree that best explains the data according to a specific criterion, such as maximum likelihood or maximum parsimony, that reflects the most likely evolutionary history of the sequences or organisms under study. This can be performed using different algorithms and models, depending on the nature of the data and the assumptions underlying the analysis.Regardless of the methodology that is being utilized to reveal grapevine genetic or genomic variability , the selection of the algorithm or method to infer the clustering analysis of populations and cultivars, is critical. Algorithms are, essentially, the equations that various statistical software use to quantify variability and finally present it as a branched tree (dendrogram or phenogram as in In the distance methods the evolutionary distances (or pairwise differences) and the construction of phylogenetic trees are put together by grouping individuals (or genotypes) that are most similar . ExampleAbovementioned methods can be a useful and informative approach for reconstructing the evolutionary history in populations and identifying patterns of genetic variation among individuals or groups by the application of any type of molecular data, including SSR . Each meVitis population. Data were fed to the Darwin software program with a matrix of pairwise FSt values. Darwin was also used by Vitis genotypes from Italy, Slovenia and Ionian islands along with the package PHYLIP  technologies significantly changed phylogenetic analyses through the increase of the generated data focusing either in genomic level or at specific loci. In any case, the vast array of generated data permits the increase of the number of taxa that can be included in the analyses . On the V. vinifera cv. “Nebbiolo” clones after revealing unique SNP markers while Such efficient NGS platforms can be used to detect SNP to identify genetic differences not only between varieties but also between clones. For example, Vitis accessions from a wide geographic distribution that helped to identify certain relations between the domesticated grapevines.In most of the cases, NGS needs the recruitment of a reference genome to highlight differences and relationships between individuals. V. vinifera common and feral accessions as well as other Vitis species. Among them, a de-novo assembled reference genome of V. riparia has been created, utilizing a third generation long read NGS technology  selection methods were relative robust and efficient techniques of this category that are based on gene enrichment. Additionally, there are the bisulfite sequencing approaches that may also improve the assessment of epigenetic diversity  from multiple samples . ISSRseq7.2.3Some years earlier, Although SSRs have been successfully adapted in DNA fingerprinting , they prAmpSeq is a promising method to make it an appropriate genotyping tool for diverse species, including grape, since it offers flexibility, high-throughput, low-cost, accuracy, and semi-automated analysis . In gene8Vitis. As Vitis is being cultivated since ancient times a more precise and detailed roadmap to fingerprint, conserve and protect the diversity pool should be established. Results show that although a wide array of molecular techniques or statistical methods have been employed, there is no an established roadmap. In the face of climatic changes and the increase of food demand across the globe the new technologies should be incorporated with the human intelligence to create a holistic for Vitis cultivation, adaptation, and protection. Nonetheless, it’s always important to consider the limitations of any marker system and to use multiple markers and methods to fully characterize genomic diversity in grape populations.In this review we presented the recent molecular methods which have been used to characterize the germplasm of the genus ET and FV contributed to conception and design of the study. ET and ST wrote the first draft of the manuscript. All authors contributed to the article and approved the submitted version.


This research presents the application of a beam finite element, specifically derived for simulating bending–torsion coupling in equivalent box-beam structures with curvilinear stiffeners. The stiffener path was simulated and optimized to obtain an expected coupling effect with respect to four typical static load cases, including geometric constraints related to the additive manufacturing production method. The selected load condition was applied to the centroid of the beam section, and the structure performance was consequently determined. A variation in load position up to one-fourth of the beam width was considered for investigating the stiffener path variation corresponding to a minimum bending–torsion coupling effect. The results demonstrated the capability of such a beam finite element to correctly represent the static behavior of beam structures with curvilinear stiffeners and show the possibility to uncouple its bending–torsion behavior using a specific stiffener orientation. The simulation of a laser powder bed fusion process showed new opportunities for the application of this technology to stiffened panel manufacturing. The resulting slender structures are highly flexible and are subjected to aeroelastic instabilities [High aspect ratio wing configuration and weight reduction can improve aircraft energy efficiency, reducing CObilities ,2,3,4,5,bilities .Aeroelastic tailoring demonstrates its important advantages when orthotropic materials are involved in the design. Composite material lay-ups can be optimized to obtain a desired behavior in connection to functionally graded materials (FGM) ,9,10,11 The optimization of material orientation for aeroelastic tailoring has been widely investigated and enlarges the design space for next-generation wings. Weisshaar  used a sKameyama et al. examined  the effeThe optimization process can be very demanding in terms of time and computational costs. Equivalent models or beam elements can be adopted to find optimal solutions for the early design stages. Danzi et al.  used an In the present work, a beam finite element with bending–torsion coupling formulation , developAn additional optimization procedure was considered to obtain a self-supporting structure in the additive manufacturing production scheme by selecting the right stiffener orientation for minimizing the support structure extension and weight. General guidelines are available in literature and the ISO/ASTM normative ,31,32. A® V. 2.0, which was developed by ITACAe S.r.l. Asti, Italy and SimTech Simulation et Technologie SARL Paris, France for enhancing the AM application to the curvilinear stiffener box-beam configuration. The software was based on the FE discretization of the macro-scale process; this class of models can be used to understand the overall temperature progressions and deformations during the process, as shown in [A static analysis of the resulting optimal configurations subjected to the related loads was performed with two finite element (FE) models: a SHELL FE model and a TETRA10 FE model. The static results were compared to the ones computed by the BTCE model to verify its simulation capabilities in the presence of curvilinear stiffeners and its performance as an optimization tool. The manufacturing of a portion of the optimized beam by means of the laser powder bed fusion (LPBF) process was simulated with the software AMTOPshown in ,36,37,38The objective of this work is to investigate the capabilities of the BTCE as an optimization tool to find a desired box-beam structure configuration at a very early design stage and to assess its accuracy in determining structural performances in the presence of curvilinear stiffeners. Moreover, the presented research explores the possibilities of AM production for such a stiffened configuration, taking into consideration related geometric constraints.The research paper is organized as follows: the second section briefly presents the characteristics of the BTCE, with a focus on its derivation. In the third section, the geometry of the box-beam structure, the optimization problems, and the finite element models are described. The fourth section contains the results, while the conclusions are outlined in the fifth and last sections).y- and z-axes, The finite element used in this work was a two-node finite element with six degrees of freedom per node, derived by Patuelli et al. , which iThe structure considered in this work was a circumferentially asymmetric stiffness (CAS) configuration, and the stiffness coefficients were obtained with Equation (2).The coefficients were defined in a three-dimensional cartesian reference system (rding to .(3)A11*Considering the external loads Galerkin’s method was adopted to find the element stiffness and mass matrices. The method consists of expressing the variables Once the shape functions were defined, the set of the function was multiplied by a residual function In this way, the error between the shape function and the equation of the problem was minimized. The results of this procedure were the discrete equations of motion, written in the form:Further details on shape functions, element stiffness, and mass matrices derivations can be found in .The coefficients were constant along the element. For a beam structure with curvilinear stiffeners or fibers, the orientation The generic box-beam structure analyzed in this work is depicted in  used in ,29, wherThe stiffener orientations evaluated at prescribed control points with Equation (8) were considered design variables in the topology optimization procedure: rding to ,42,43.(The optimization problem for the static bending–torsion coupling cases can be formulated as (9):While the optimization problem for the load cases where the objective is to find an uncoupling configuration can be written as (10):fmincon”. The allowable orientations ranged from The optimization was carried out with the MATLAB optimization algorithm “rding to ,29,44, aThe optimization was obtained with 200 initial couples of The optimization was performed by considering different load cases (LC) listed in The first optimization was designed to find the configuration, which resulted in a coupled bending–torsion deformation with the highest level of strain energy and with constraints on maximum deflection and minimum torsion angle. In this case, the load was applied on the section centroid (LCi-C). The second optimization was arranged to find the configuration that separated bending and torsion when the load was applied at one-fourth of the beam width (LCi-U), which was equal to a distance of tion see . This paThe constraints applied for each optimization are listed in The constraints reported in As an example of the application for beam structure design optimization, the optimal values related to The chosen configurations were subsequently simulated with three different FE models: a 10 BTCE model, a SHELL FE model, and a TETRA10 FE model, following the procedure and the FE modeling described in . For eac® V. 2.0. AMTOP® V. 2.0 is a platform of software tools developed to analyze and optimize additive manufacturing products and processes. The platform includes several algorithms to efficiently optimize the orientation of the part on the build platform [The additive manufacturing production of a portion of a stiffened panel, including related constraints, is represented in platform  and evalplatform ,47. The Conduction, convection, and radiation heat transfer phenomena, as well as the non-linear mechanical elastic–plastic behavior, were taken into account in the analysis through the introduction of temperature-dependent material properties into the FE model. The evaluation of distortions of the part, compared to the nominal geometry, was carried out with the alignment of calculated and nominal part geometries through a root-mean-square error minimization method.In Equations (13) and (14), The optimization procedure revealed that many different configurations gave a similar response and therefore a comparable strain energy level. However, it was possible to determine the configurations that achieved the highest strain energy values. The optimization results are presented in For the cases where the desired solution was meant to eliminate the bending–torsion couplings, it was interesting to note that the acceptable configurations laid on a line for each load case, and that the configurations with the highest strain energies were similar. The optimal solutions are listed in The optimized angles for each configuration were approximated to the nearest value within 0.5°. Due to the similarities between the optimal solutions for the decoupling cases, a single configuration was chosen. The resulting configurations are listed in Three different FE models were created for each one of the geometries presented in The results obtained with the different FE models are reported in In the majority of the considered cases, the geometries obtained from the optimal solution produced a deformation compliant with the design constraints. The static analysis revealed some differences with respect to the deformation results obtained with the optimal solutions reported in A good agreement between the different models were determined, showing a relative difference generally below 6% with respect to the TETRA10 FE model results and below 10% with respect to the SHELL FE model results. These differences were justified, considering the BTCE model assumptions. The developed beam element considered the stiffeners straight along the element length; moreover, an equivalent single layer material was adopted to describe the stiffened panel behaviors. In addition, the beam element section was considered non-deformable. However, the BTCE model demonstrated a good fidelity in representing the static behavior of a box-beam structure with curvilinear stiffener panels. This was a very interesting result for a tool useful in the preliminary design environment.®; the reported results were displacements of the finite element model nodal coordinates from the starting geometry after the removal of the base plate and powder finite elements. The chosen process parameters and the designed geometry did not generate support structures minimizing the post-production machining. The deformations induced by the release of the stresses cumulated during the part cooling were represented in the principal directions. The simulation showed that the part could be produced with LPBF, obtaining a component with deformations lower than 0.82 mm.The application of a beam finite element with bending–torsion formulation for the stiffener path optimization of box-beam structures with curvilinear stiffened panels was presented and validated. The optimization was devoted to three different load cases applied on the beam axis, including one typical situation related to manufacturing geometric constraints in the AM process. The objective function of the optimal procedure was focused on the maximum strain energy under the prescribed load related to the selected configuration under maximum vertical deflection and minimum torsional angle global constraints. With this method, the highest level of bending–torsion coupling was achieved.A second optimization considered the same load cases but was positioned at one-fourth of the beam width, generating an additional torsional moment. In this case, the objective of the investigation was focused on minimizing the bending–torsion effect and therefore obtaining the maximum strain energy, with the torsion angle at the tip equal to 0.The optimization results were converted into a beam structure design to assess the structural performances of the chosen configurations and to verify whether the BTCE was capable of correctly representing the deformation under static loads of beam structures with curvilinear stiffeners. A TETRA10 FE model, a SHELL FE model, and a BTCE model were created for each design, and a static analysis was performed. The comparison between the different FE models revealed a good precision of the BTCE, with relative differences in the deformation results less than 6% in most of the cases when compared to the TETRA10 FE model results and less than 10% when compared to the SHELL FE model. The discrepancies between the different models can be explained by considering the assumptions made for the BTCE derivation. The developed beam element considered the stiffeners straight along the element length and reduced the stiffeners to an equivalent single layer. In addition, the beam element section was considered non-deformable.The potential of the BTCE as an optimization tool and as a static analysis tool for beam structures with curvilinear stiffeners was confirmed. Moreover, the possibility to obtain a specific configuration capable of enhancing or diminishing the effect of bending on torsion and vice-versa was also demonstrated.® thermo-mechanical simulation revealed that residual stress induced deformations smaller than 0.82 mm on the final component, confirming the possibility for the AM production of stiffened panels for such performant beam structures.The optimal configuration related to geometric constraints for AM production with a self-supporting structure that minimized the post-production machining was also performed. AMTOP


Various heat pump technologies are examined from an environmental perspective using a life cycle assessment approach. The investigated heat pump systems utilize air, ground, and water as their energy sources. Additionally, an innovative heat pump powered by green hydrogen is investigated in this study, to evaluate its environmental impacts and potential to commercialise on a large scale. A range of supply chain scenarios is explored, considering the main suppliers of the UK market. The reshoring heat pump industry and supply chain are evaluated to enhance energy resilience and security within the UK. The findings indicate that the hydrogen-based heat pump presents a promising option for the UK market, offering the advantages of reducing stress on the national grid network and minimizing the environmental impacts associated with the supply chain. Furthermore, a forecasting analysis is conducted based on the UK's net-zero emission plan to provide insight into future developments. Currently, numerous researchers specializing in transitions are addressing major sustainability issues like climate change2. Before bringing a technology to the market, it is crucial to evaluate its environmental impact. Newly conducted studies suggest that by 2050, there is an expected rise of 50% in the release of GHGs, establishing it as the main and most significant element driving the progression of climate change3. Taking sufficient preventive actions is crucial to prevent or alleviate the harm resulting from climate change4. Heat pump technologies represent ecologically conscious methods for enhancing energy efficiency, possessing the capability to substantially lower carbon emissions linked to the heating of buildings on a considerable magnitude5. A heat pump serves as an energy-conscious solution that can aid in regulating electricity consumption through intelligent demand-side management, particularly as renewable energy becomes more prevalent in the grid6. Several studies have been done on life cycle assessment (LCA) of different types of heat pump technologies.The transition to low-carbon technologies to provide heating and cooling energy required for domestic and industry sectors and reduce the dependency on fossil fuels are among the top priorities of the governments. However, expanding certain technologies on a large scale should be aligned with climate change and greenhouse gas (GHG) emission reduction policies. The swift transition to renewable energy is anticipated to promote economic sustainability and emissions reduction, aligning with the principles of the European Green Deal7. Due to the implementation of the Future Homes Standard, the UK Government has set a nationwide goal to eliminate fossil fuel-based heating systems from new residential constructions beginning in 20258. These pieces of evidence substantiate the notable need for increasingly eco-friendly technologies such as heat pumps in the near future. In the UK, the predominant portion of units sold, comprising 87%, consists of air-source heat pumps (ASHPs), trailed by ground-source heat pumps (GSHPs) and water-source heat pumps (WSHPs) at 9%. The residual 4% of the market is represented by hybrid systems, amalgamating a heat pump with a conventional fossil-fuel boiler in a compact configuration9. Outlined within the Heat and Buildings Strategy10, the UK Government detailed its intentions to achieve a minimum of 600,000 heat pump installations annually by 2028. This strategy also acknowledges the potential contribution of hydrogen in the decarbonization of heat, with the notion that hydrogen could cater to up to 4 million households by 203511. The most promising opportunity for heat pumps in the UK lies within larger residences, particularly those that are not connected to the main power grid12. The benefits of hydrogen include its abundant availability, minimal emissions, a significant reduction in GHGs, and the reversibility of its generation process 13.The dominant heating system utilized in residential structures within the United Kingdom (UK) consists of central heating operated by a natural gas-fuelled boiler, accounting for approximately 92% in 201714. Numerous studies have focused on either ASHP15 or GSHP19, while others have conducted a comparative LCA of diverse heating and cooling systems  and comparison with most conventional heat pump technologies such as ASHP and GSHP28. However, the water-source heat pump has received comparatively less attention in research endeavours29.Given that a significant portion of heat pump components are imported from abroad, mitigating the environmental effects of the heat pump supply chain becomes imperative. To meet the net-zero emission target, emissions from heat and the building sector are required to be net-zero30. Increasing environmental and societal stresses resulting from possible disruptions in supply chains are compelling businesses to adopt sustainable and adaptable strategies31. Furthermore, adopting efficient and reliable low-carbon technologies can create a more resilient energy system, less vulnerable to market fluctuations, and enhance energy security and resilience32.The UK's net-zero emission strategy concerning the building sector will necessitate the widespread adoption of low-carbon technologies such as heat pumps, which offer a viable replacement for gas-based boilers. Consequently, the heat pump market and its supply chain will play a significant role in shaping the energy security and resilience of the UK. Incorporating energy resilience into policy and program development can protect and expedite the shift toward accessible and cost-effective renewable energy for different sectors28, the possibility of utilizing hydrogen as an energy source for gas-powered equipment was explored. However, to the best of our knowledge, considering hydrogen as an energy source for heat pumps has not been studied before. Furthermore, an extensive set of supply chain scenarios has been expanded for all these technologies, drawing from the latest report released by the UK government and the main supplier within the UK market. The aim is to compare each scenario in terms of their environmental impacts and their connections with energy security and resiliency. A forecasting evaluation to find the damaging environmental impact reduction of the heat pump supply chain, aligned with the UK's net-zero emission plan by 2050. Additionally, the discussion extends to the influence of heat pump technology on energy resilience and security within the UK.The majority of existing research has concentrated on assessing the environmental effects of three conventional heat pump technologies , however, in this study, we have assessed a novel heat pump type named hydrogen-based heat pump (HSHP) which operates using green hydrogen derived from renewable energy sources instead of relying on electricity from the grid network. In one researchA sustainable and resilient supply chain is essential for improving the energy security of the building sector. The supply chain scenarios in this study are developed based on the most updated UK government report about the heat pump supply chain in the UK. The considered phases in this assessment are raw material extraction, transportation, manufacturing, Operation and Maintenance (O & M), Assembly and Installation (A & I). The simplified scheme of the general heat pump supply chain scheme is shown in Fig. 33. Since the turn of the century, LCA has been put into practice through implementation in world policy34. The recognition of LCA's worth in quantitatively evaluating the environmental impacts of product life cycles has grown, and it is increasingly employed to aid decision-making in policy and governmental contexts35. All exchanges of energy and materials with the environment during the entire lifecycle should be gathered and analysed in terms of their ecological consequences36. The significance of LCAs lies in their capacity to reveal both the locations and the comparative significance of environmental effects37. It is a widely recognized and globally standardized approach employed to compute the environmental discharges associated with a product or process throughout its various life cycle stages38. The LCA carried out in this research adheres to the methodology outlined in the ISO 14,040 standard39. It comprises several main steps which are goal and scope definition, life cycle inventory analysis, impact assessment methodology, and interpretation of the results.LCA emerges as a valuable instrument for making knowledgeable choices and systematically tracking a wide array of ecological effects across the complete spectrum of product creation. The utilization of LCA establishes and tackles crucial ecological sustainability concerns vital for subsequent growth and expansionThe primary step of the LCA study is determining the goal and scope of the project. The main goal of this study is to conduct a comparative life cycle supply chain assessment of different heat pump technologies including a novel system named HSHP. Diverse supply chain pathways are developed to compare carbon footprint. The supposed system boundary is cradle-to-gate. The selected functional unit for all systems is considered to be 1 kWh of generated energy. OpenLCA v. 1.11.0 software is applied to conduct the LCA modelling.40. Several databases are applied to collect the required data for systems modelling such as Environmental Footprint (EF), Ecoinvent v3.9 databases, and some literature42.In the process of inventory analysis, information is gathered concerning multiple elements, encompassing the utilization of resources, energy expenditure, water usage, emissions released into the air, water, and soil, as well as the creation of waste. The inventory analysis facilitates a thorough evaluation of the environmental effects of the material, allowing scholars to pinpoint and comprehend the critical environmental hotspot issues. This pinpointing of key areas can direct the focus of endeavours toward environmental enhancement and offer insights for decision-making. This stage establishes the groundwork for following LCA stages, which are impact assessment and interpretation43. ReCiPe 2016 midpoint method is applied to assess the environmental consequences of the systems in order to provide more detailed understanding of the underlying processes and help identify areas where more targeted improvements in reducing environmental impacts. While endpoint methods can provide a broader perspective, the midpoint approach aligns better with the research goals and provides the necessary granularity for the analysis.In the life cycle impact assessment stage, characterization criteria are predominantly employed to convert the LCI data into quantitative estimations of the potential environmental consequences linked to the product44. The interpretive stage entails a thorough evaluation of the outcomes of an LCA investigation, encompassing both the inventory and the impact assessment phases, aligning with the study's defined objectives and scope45.After conducting the assessment of environmental impacts, the outcomes need to be scrutinized and explained with the earlier investigations interpretation phase, which represents the final stage of LCAHere, the outcomes of environmental evaluation concerning some main impact categories stemming from the supply chain of the heat pump industry are presented. These impacts are selected as they have the most dominant damaging impacts. Figure Generally, the supply chain of ASHP exhibits a greater carbon footprint impact when compared to other technologies that have been examined. This discrepancy is primarily attributed to the materials employed during the manufacturing and O&M phases. The materials used in the construction of ASHP systems, such as low-alloyed and reinforcing steel, copper, and insulation materials for piping, exceed those used in other technologies. These specific materials are the primary drivers of the increased carbon footprint associated with the manufacturing process of ASHP. Furthermore, GSHP and WSHP necessitate a lesser quantity of these materials during the manufacturing stage. Another significant factor contributing to the higher carbon footprint of ASHP systems is the increased utilization of refrigerants in comparison to other cases. The UK scenario for ASHP supply chain carbon footprint is similar to supplying from Spain and Ireland. However, in other cases, the supply chain carbon footprint is lower for the UK scenarios . The most pollutant scenario for all studied cases, is China (both 50% and 100% of manufacturing capacity). Assuming 50% of manufacturing in the UK caused a decrease in carbon dioxide emission for all scenarios that will lead to less transportation-related pollution. It is evident that the carbon footprint of HSHP is consistently much lower than that of other technologies in all scenarios and supply chain pathways. This is primarily attributed to the elimination of electricity requirements for the system's operation throughout its lifespan. The reduction or elimination of reliance on the grid network has a beneficial effect on reducing carbon emissions during the operation of these systems.The marine ecotoxicity (ME) category for all technologies and supply chain scenarios is presented in Fig. Figure Figure 42 which is the main energy provider for the building sector in the UK, investing in the heat pump industry and supply chain with significantly lower environmental impact has been considered as a priority plan for government. One of the main interventions that should be implemented by government and local authorities is promoting and investing in grid network infrastructure in the UK to increase the renewable and clean energies share in the energy mix. Since the O&M phase of heat pumps is the primary source of carbon dioxide emissions and given that existing systems rely on electricity for their operation, a crucial requirement is a more sustainable energy mix. This would be aligned with net-zero emission, energy security, and resiliency plans. On one side, a growing share of renewable resources in the energy mix results in less fossil fuel and natural gas demand, on another side, it eliminates the dependency on natural gas prices and relevant fluctuations as well as availability of the natural gas which will promote the energy security and resiliency in the UK. It also will decrease the environmental impact of the heat pump supply chain which could improve the sustainability of the heat pump industry in the UK. Figure Figure The challenges of supplying the required heating and cooling demand for the buildings sector in the UK are under government, stakeholders, and local authorities’ attention. Increasing the energy price for households in the UK in recent months, challenges of natural gas application in installed boilers in buildings, its relevant pollution, and dependency on natural gas are the main elements that can threaten the sustainability and energy security and resiliency of building sector in the UK. Expanding different heat pump supply chain scenarios which are the main suppliers of the UK market is done in this study to conduct a comparative LCA of all scenarios. This study seeks to improve the sustainability of the heat pump supply chain. Base scenarios are developed based on 100% of production in exporter countries and then importing them to the UK. Among the evaluated scenarios, Sweden has the most sustainable supply chain path with a lower carbon footprint impact. The computation demonstrates the pivotal importance of the composition of electricity sources in determining the environmental sustainability of the heat pump supply chain. Enhancing the proportion of renewable energy sources within the energy mix can impact a national energy security and resilience. The results indicated that presently, the primary contributor to the carbon footprint of traditional heat pumps is associated with their operation and maintenance (O&M). However, by 2050, as per the defined net-zero emissions plan, the adverse effects of O&M will significantly diminish.The findings indicated that either setting up a new production line for heat pumps or enlarging the existing one could significantly reduce the environmental footprint. Also, based on the UK government's plan to reach the net-zero emission goal in the building sector, it is crucial to shift to a cleaner system like a heat pump instead of using natural gas-based boilers to improve the energy security in the UK and stably supplying the buildings' energy for peak demands and unpredictable circumstances. However, development of heat pump application and installation should be accompanied by a reduction of environmental impact over the entire supply chain of heat pump. Heat pump supply is immature in the UK and has huge gaps which makes it challenging to develop its application and installation in a short period. Reshoring or production line expansion will reduce the distribution and transportation-related pollution and can guarantee the supply of the UK market demand and decline the dependency on foreign markets.In the future, once manufacturing capacity is expanded to meet domestic demand, exporting could become advantageous for the UK. These various factors collectively enhance the energy security and supply chain resilience within the heat pump industry. Additionally, this research has explored HSHP (hydrogen-supported heat pumps), which demonstrates significant potential as an eco-friendly option for the building sector. The results have shown that using green hydrogen as an energy source for heat pumps, as opposed to relying on an electricity grid or natural gas in other types of heat pumps and boilers, can substantially reduce the carbon footprint of energy production. For HSHP to thrive, it's not only the heat pump supply chain that needs development and optimization, but also the supply chains for hydrogen production technologies, such as electrolysis, which should be strengthened within the UK. The UK exhibits substantial potential for manufacturing and advancing hydrogen production systems domestically. It's worth noting that the UK government has already established a comprehensive national hydrogen strategy aimed at fostering the production and utilization of hydrogen.To cover the market with HSHP, both the heat pump and electrolysis supply chain should be developed in parallel unless it can affect the security and resiliency consistency. Another point that should be considered in a resilience heat pump supply chain is manufacturing capacity development to supply all main components of heat pump units in the UK such as compressor, evaporator, valves, piping, insulation, and refrigerants. The UK is well positioned in manufacturing some components like compressor, however, there are considerable gaps in other component supplies.46, it can assist the government in shaping future trade strategies in alignment with the net-zero emissions plan and a more environmentally sustainable and resilient supply chain strategy. Additionally, this research assessed the supply chain's environmental impact across various timeframes, including projections up to 2030, 2040, and 2050. It showcased the potential of a net-zero emissions plan in mitigating ecological impacts, which can attract investment, garner support from local authorities, and influence decision-makers to allocate more financial resources to expand renewable energy sources and their integration into the grid network. The outcomes of this study could also help policymakers choose more sustainable supply chain scenarios and routes to counter climate change, reduce toxicology and global warming damaging consequences. Such actions to improve UK energy sustainability, resiliency and security are poised to have substantial direct and indirect benefits on a wide range of industries and sectors.The findings of this research offer valuable insights to policymakers and stakeholders, providing a comprehensive understanding of the heat pump supply chain throughout its lifecycle. This study has unveiled the environmental consequences associated with each supply chain route. Furthermore, by comparing the options of reshoring and developing heat pump-related industries in the UK and addressing carbon footprint and toxicity concernsSupplementary Information.


Magnetic fluids, as smart nanomaterials, have been successfully used in sealing applications and other fields. However, the temperature of magnetic fluids in the sealing gap is a key factor affecting sealing performances, limiting their application in high-speed sealing fields. Since obtaining a direct measurement of the magnetic fluid’s temperature is difficult, due to the small clearance, accurately calculating the maximum temperature of the magnetic fluid layer in high-speed seals is crucial. Herein, a mathematical model for calculating the maximum temperature of the magnetic fluid layer was established, by using a reasonable simplification of high-speed sealing conditions, and the calculation formula was modified by studying the rheological properties of the diester-based magnetic fluid. The results suggest that the calculation of the maximum temperature is influenced by viscous dissipation, and both are related to the rheological characteristics of magnetic fluids. When the influence of rheological properties is ignored, the calculation results are not accurate for higher-velocity seals, but the calculation model applies to lower-velocity seals. When the influence of rheological properties is considered, the calculation results obtained by the corrected formula are more accurate, and they are applicable to both lower- and higher-velocity seals. This work can help us more accurately and conveniently estimate the maximum temperature of magnetic fluids in high-speed seal applications, which is of theoretical and practical research significance for determining sealing performances and thermal designs. A magnetic fluid (MF), a stable colloidal solution, is usually formed by ferromagnetic nanoparticles that are uniformly suspended in a nonmagnetic carrier fluid, utilizing a surfactant ,2. It caIn previous studies, a variety of factors affecting the performance of magnetic fluid seals have been extensively investigated. Studies on the performance of magnetic fluid low-speed seals occupy the majority of them ,6,7. TheSeveral studies have been conducted on viscous dissipation and temperature in magnetic fluid seals. As a non-contact seal, although the friction torque is generated by internal friction in the fluid, the heat accumulated during operations can be significant, due to the small gap, the low volume of magnetic fluids, and the high rotational speed. Hence, some research has focused on the two important parameters of torque friction and viscous dissipation, as they determine the temperature of magnetic fluids in the seal. Li presented analytical methods for studying the technical issues of magnetic fluid seals, such as high speeds and large diameters. It was observed that the primary heat source was viscous drag, and the viscosity of magnetic fluids changes with temperature, leading to complex heat dissipation . Cai et In addition, some experimental studies on the temperature in the sealing gap have also been carried out. Szydlo et al. conducted an experimental study on the temperature and frictional moment of magnetic fluid seals operating under vacuum conditions. It was concluded that the temperature of the seal increases with an increase in rotational speed and the number of sealing stages, both resulting in high viscous drag . BorbáthIn summary, previous studies conducted some theoretical and experimental studies on temperature and viscous dissipation in magnetic fluid seals. In terms of theoretical research, the effects of viscosity and other factors on friction torque and viscous heat were mostly studied, but the rheological properties of magnetic fluids under sealing conditions have rarely been systematically considered in viscous dissipation calculations. In terms of experimental research, most studies focused on the effect of temperature on the sealing capacity, but the temperature of magnetic fluids in the seal makes it difficult to achieve direct and accurate measurements, due to the narrow sealing gap. Therefore, the calculation, and quantification, of temperature in magnetic fluid seals is still incomplete, especially with respect to studying the maximum temperature of magnetic fluids in high-speed seals. This article establishes a calculation model of the maximum temperature of magnetic fluid layers in the sealing gap, by simplifying high-speed sealing conditions. The rheological properties of magnetic fluid under the simulation conditions of high-speed seals are measured, and the formula for calculating the viscous dissipation and MF temperature is subsequently modified. The maximum temperature of diester-based magnetic fluids is calculated accurately, under the condition of high-speed seals without cooling. This theoretical calculation can help to guide the application of magnetic fluids in high-speed sealing fields conveniently and quickly, such as judging the performance of magnetic fluids, sealing capacity, the cooling conditions of the seal, etc. We anticipate that our study can lay theoretical and practical foundations for promoting the research of magnetic fluid high-speed seals, which have great potential applications in military and aerospace and sealing other high-end equipment, in the future.3O4-diester magnetic fluid studied herein was prepared via chemical co-precipitation by our group. The sample was successfully applied in commercial conditions and placed stably for more than three years without visible particle agglomeration. The TEM image of Fe3O4 nanoparticles was observed by the JEM-2100F transmission electron microscope. The FeIn this study, the magnetic fluid’s flow in a high-speed seal clearance is simplified into an incompressible stable flow, in a two-dimensional plate model. In the actual working condition, the sealing gap is narrow, and the magnetic fluid is wrapped by the shaft, pole pieces, and shell; thus, the temperature and heat transfer process of magnetic fluids in the clearance cannot be measured directly. Therefore, the following reasonable assumptions and simplifications were introduced, to calculate the temperature of the magnetic fluid layer in high-speed seals: (1) completely axisymmetric; (2) ignoring the heat transfer along the axial direction, and only the radial heat transfer is considered; (3) the height of the magnetic fluid layer is far smaller than the radius of the shaft, so it can be considered as a flat infinite plate model; (4) the characteristic length of the fluid layer is much larger than its height, and the temperature of the magnetic fluid in the central layer is considered in engineering calculations. A schematic diagram of the calculation model herein is shown in Here, The following governing equations are used to study the flow and heat transfer of magnetic fluid in the above-defined model.For a steady state, the velocity distribution at a certain fluid layer height can be approximately regarded as the following linear relationship:For a given rotating speed, viscous dissipation is determined when the viscosity of a fluid is regarded as a constant, and it can be calculated by the following formula.Therefore, the energy in Equation (2) can be expressed as follows.The following dimensionless parameters are introduced to transform the above Formula (5) into the dimensionless form:Substituting dimensionless parameters (6)–(8) into Formula (5), the dimensionless expression of the temperature field can be obtained.By carrying out the double integration of Equation (9), the general solution of dimensionless temperature is obtained:Under the condition of high-speed sealing, it is considered that the heat flux generated by viscous dissipation is constant throughout the boundary between the rotating shaft’s surface and the magnetic fluid, and the upper boundary between the magnetic fluid and the pole piece surface maintains a constant temperature. Therefore, the following boundary conditions were applied to solve Equation (10):By substituting boundary condition (11) into Equation (10), the following integral constants can be obtained:The dimensionless temperature distribution expression of the magnetic fluid layer is further obtained:According to dimensionless parameter expressions (6)–(8), the dimensional expression of the magnetic fluid’s temperature distribution is as follows:We take a derivative of Formula (15) and obtain the maximum dimensionless temperature when We further obtain the following equation:By substituting the above Formula (18) into Formula (16), the maximum temperature of the magnetic fluid layer in the high-speed seal can be calculated as follows:−1) to allow the viscosity to reach high shear-limiting viscosities.Viscosity is one of the important physical parameters of MF, and it is affected by magnetic fields, shear rate, and temperature. To accurately obtain the viscosity of MF under the sealing conditions, an Anton Paar MCR302 rotational rheometer was used, to measure the rheological properties of MF in a simulated seal environment. The relationship between the shear stress and shear rate was measured at room temperature, as shown in −1, as indicated in Magnetic fluids produce magnetic viscous effects under a magnetic field, and the variation in viscosity with respect to the magnetic field was measured experimentally at a shear rate of 1000 s−1. As depicted in Based on the results of Viscosity is the root cause of thermal dissipation within the magnetic fluid seal, and the temperature increase generated by viscous frictional dissipation is the key reason for the degradation, or even failure, of high-speed magnetic fluid seals. At the starting operation of high-speed seals, the magnetic fluid’s temperature was lower and its viscosity was greater, resulting in higher dissipation power due to viscous friction, which caused the temperature increase in the seal gap. When magnetic fluid temperature increases, viscosity decreases and the dissipation power decreases. Therefore, viscosity, dissipation power, and temperature interact and influence each other. In order to accurately calculate the thermal dissipation power during high-speed seal operations, the viscosity–temperature relationship of magnetic fluids is taken into account. Based on the study of rheological performances in The basic form of magnetohydrodynamic equations is similar to that of conventional fluids, with the exception that magnetic fluid is subjected to an additional magnetic force in the presence of magnetic fields. In high-speed magnetic fluid seal conditions, the following assumptions are made: (1) Magnetic fluid is a homogeneous incompressible Newtonian fluid; (2) it achieved a stable state, By integrating Equation (22), and then substituting the boundary conditions in (24), the analytical solution of the tangential velocity distribution in the l indicates the total axial length of the actual contact between the magnetic fluid and shaft.The subjected viscous shear stress of the magnetic fluid in the sealing gap is expressed as follows:The viscous resistance torque leads to the generation of frictional dissipation power; thus, its expression can be described as follows.From Equation (28), in addition to the influence of the seal’s structural parameters and rotating shaft speed, the viscosity of the magnetic fluid is an important factor affecting the dissipation power.Based on the results and analysis in Substituting the above equation into Equation (9) yields the modified formula for calculating the viscous frictional dissipation power of high-speed diester-based magnetic fluid seals.The following high-speed sealing conditions were taken as an example for calculating the maximum temperature of the diester-based magnetic fluid layer. The radius of the rotating shaft was 24 mm, the rotating speed was 1000–8000 rpm, the sealing clearance was 0.1 mm, and the initial boundary temperature was 20 °C. When the rheological properties of magnetic fluids are ignored, the viscosity of the magnetic fluid can be considered as a constant under the sealing conditions, and then the heat flux is expressed as follows.According to the above equation, the heat flux applied to the sealing gap due to viscous dissipation at different linear velocities was calculated, as depicted in In order to verify the correctness of the calculation model in According to the previous study, described in T in the equation denotes the average integration temperature, and it is obtained by the following equation:When performing viscosity calculations for diester-based magnetic fluids, based on viscosity–temperature expression (29), under the characteristics of sealing conditions, The calculated average integration temperature at different velocities was substituted into Equation (29) to obtain the corresponding viscosity, in order to further obtain the corrected heat flux and the corrected calculation of the magnetic fluid’s maximum temperature. As shown in As stated above, the formula for calculating the maximum temperature of the diester-based magnetic fluid layer in high-speed seals, was corrected by considering the rheological properties of the magnetic fluid as follows:In the present work, a mathematical model for calculating the maximum temperature of the magnetic fluid layer in the sealing gap was established, based on the simplified high-speed sealing conditions. By analyzing the factors affecting the accuracy of the calculation model, the rheological characteristics of the magnetic fluid were measured and the viscous dissipation formula was modified. Thus, a modified calculation formula of the maximum temperature of magnetic fluids in the seals was obtained. The main conclusions from the calculation results are as follows.Under high-speed sealing conditions, the temperature of the magnetic fluid in the sealing gap is mainly influenced by the viscous dissipation generated by viscosity, while viscosity is also influenced by the temperature. When the effect of the rheological properties of magnetic fluid on viscous dissipation is ignored, this calculation model applies to low-speed seals, and the calculation results are not accurate at high-speed seals. When the effect of the rheological properties of magnetic fluids on viscous dissipation is considered, this calculation model applies to both low- and high-speed seals, and the calculation results are more accurate. The correction formula for calculating the maximum temperature of the magnetic fluid is obtained based on the viscosity–temperature function of the magnetic fluid under high-speed sealing conditions. The correction formula applies to predicting the maximum temperature of magnetic fluid in the seal, without cooling, in the range of 0–20 m/s linear velocity. The accuracy of the temperature calculation in the higher linear velocity range needs to be further verified. Although the calculation model simplifies and ignores some influencing factors, and the calculation results have some deviations from the actual values, this calculation method is simple and convenient. Within the allowable range of error, the modified calculation model described in this paper can provide theoretical and practical reference values for quickly understanding and judging the performance of magnetic fluid seals and guiding engineering applications. In the future, we will further improve the modeling and solving methods of the temperature calculation based on this work, to obtain more accurate calculation results and wider applications.


The measures that were taken in many countries as a response to the COVID-19 pandemic not only brought about new stimuli in the lives of individuals, but also gave rise to various restrictions that led to discontinuities in many aspects of daily life. Therefore, the development of a sound measure for monitoring the level of perceived daily life disruption is important. The Perceived Daily Life Disruption (PDLD) scale is proposed and its initial validation based on the assessment of key psychometric properties is targeted in this study. A confirmatory factor analysis (CFA) on the PDLD scale was conducted on a representative sample (n = 1372). In addition, univariate statistics were calculated, internal consistency was tested, and unidimensionality based on principal component analysis was performed. The CFA yielded satisfactory results concerning the standard indices and achieved a high internal consistency. It was observed that the scale adequately differentiates the level of perceived daily life disruption among diverse subpopulations. Usage of the PDLD scale can be recommended; it is easy to administer and it yields acceptable results. A number of anti-epidemic measures have been implemented since March 2020, when the first COVID-19 patients appeared in Czechia and many other countries ..28].The achieved value of SRMR (0.0081) is considered acceptable when e.g., Hu and Bentler  recommenThe proposed scale seems to be invariant when the differences among key subgroups are not statistically significant; not only the mean scores are very close, but also the standard deviations show similar pattern across the observed subgroups defined by age, gender, and highest achieved education. With respect to other findings e.g., ,35,36, iThe scale that is focused on perceived daily life disruption is a novel one among COVID-19 measures . However, perceived daily life disruption also appears within other contexts, such as reactions to natural disasters , distresSince the conducted research took the form of a cross-sectional study, it is not possible to identify the direction of association between perceived daily life disruption and perceived amount of stress and reported sleeping disorders. It is not possible to recognize whether increased amount of stress and reported sleeping disorders lead to a higher perceived disruption or whether a higher perceived disruption concerning COVID-19 leads to increased amount of stress and reported sleeping disorders. Both explanations would have their own rationale; however, another type of study would be required to determine the direction of causality.There was a specific situation in Czechia during fieldwork. The interviews were conducted right after the so-called “first wave” of the pandemic, which may be characterized by the imposing of measures on the population , a high level of solidarity among individuals , and good compliance with restrictions. It would be useful to compare the results with newer data to observe the maturation effect in perceived daily life disruption.The paper provides evidence that expands the growing body of research on the effects of the pandemic on the population. The study has shed some light on plausible predictors, moderators, and mediators of perceived daily life disruption. The scale is easy to deploy and administer when it comprises only five statements. Items are not sensitive for a major part of the population and they do not impose a large burden on either interviewers or respondents.The PDLD scale provides useful feedback concerning perception of this aspect of the epidemic situation. It might serve as an indicator for evaluating interventions, monitoring the impact of COVID-19 on the population over time, and comparing different target groups. The large sample size helps to increase the generalizability of the research estimates and improve the accuracy of achieved outcomes. The added value of the PDLD scale is two-fold: the scale (a) provides more stable evidence than the direct question and (b) it might serve as a dependent variable of a higher level of measurement compared to currently used binary or ordinal variables.The newly developed scale was proved by the presented study to be reliable, internally consistent, and valid instrument to measure the level of perceived disruption of daily activities caused by COVID-19 outbreak. The study showed good properties of the scale; PDLD is invariant among subpopulations defined by gender, age, or education, and is sensitive to such life-disruptors as it was the COVID-19 outbreak.Even though the PDLD scale was developed in the context of the COVID-19 outbreak, it is a versatile tool that can help to understand how individuals manage other types of life stressors. As such, it might be used for different kinds of societal changes, not only for the COVID-19 situation. The suitability and performance of the proposed scale should indeed be tested in a wide variety of contexts. Future research could examine the correlations between the PDLD scale and anxiety and depressive symptoms , fear , anxiety (GAD-7), but also well-being, perceived quality of life, or coping strategies.


The goal of NASA’s Europa Clipper Mission is to investigate the habitability of the subsurface ocean within the Jovian moon Europa using a suite of ten investigations. The Europa Clipper Magnetometer (ECM) and Plasma Instrument for Magnetic Sounding (PIMS) investigations will be used in unison to characterize the thickness and electrical conductivity of Europa’s subsurface ocean and the thickness of the ice shell by sensing the induced magnetic field, driven by the strong time-varying magnetic field of the Jovian environment. However, these measurements will be obscured by the magnetic field originating from the Europa Clipper spacecraft. In this work, a magnetic field model of the Europa Clipper spacecraft is presented, characterized with over 260 individual magnetic sources comprising various ferromagnetic and soft-magnetic materials, compensation magnets, solenoids, and dynamic electrical currents flowing within the spacecraft. This model is used to evaluate the magnetic field at arbitrary points around the spacecraft, notably at the locations of the three fluxgate magnetometer sensors and four Faraday cups which make up ECM and PIMS, respectively. The model is also used to evaluate the magnetic field uncertainty at these locations via a Monte Carlo approach. Furthermore, both linear and non-linear gradiometry fitting methods are presented to demonstrate the ability to reliably disentangle the spacecraft field from the ambient using an array of three fluxgate magnetometer sensors mounted along an 8.5-meter (m) long boom. The method is also shown to be useful for optimizing the locations of the magnetometer sensors along the boom. Finally, we illustrate how the model can be used to visualize the magnetic field lines of the spacecraft, thus providing very insightful information for each investigation.The online version contains supplementary material available at 10.1007/s11214-023-00974-y. Europa Clipper is set to launch in October 2024 and will perform Mars and Earth gravity assist maneuvers prior to entry into the Jovian system in 2030 where multiple flybys of Europa  and show that it is capable of extracting the ambient field in the presence of the complex, but radially-decaying contaminating spacecraft field, and also describe how this performance metric can be used to optimize the location of the three sensor locations along the 8.5-m boom. This spacecraft magnetic field model will be coarsely validated during the assembly, test and launch operations (ATLO). However, the true magnetic signature of the spacecraft can only be realized in flight as it is challenging to characterize on the ground due to the presence of stray laboratory fields, Earth’s magnetic field, material thermomagnetic discrepancies, and restrictions on boom and solar array deployments and subsystems/instrument power-on states. Therefore, multiple characterization campaigns are scheduled after launch during the 5.5-year cruise to the Jovian system. Here we extend this previous work to accommodate a three-sensor configuration to characterize and remove the complex magnetic field of the Europa Clipper spacecraft Figs. , 2. The As it is essentially impossible to accurately measure the entire spacecraft magnetic field in the flight configuration on the ground, modeling, simulation, and testing are the only ways to ensure the magnitude of the spacecraft field is at or below its required levels at the positions of the magnetometer sensors and Faraday cups. To accomplish this, a magnetic moment is first allocated to all potential DC and AC current sources and magnetic materials on the spacecraft, arising from the various subsystems, instruments, and magnetic mechanical structures. This task is part of the magnetic cleanliness control program developed by the Electromagnetic-Interference (EMI) and Electromagnetic-Compatibility (EMC) team at JPL , and magnetic moment self-canceling orientations, to effectively null large-scale residual fields. Each source is independently measured by the EMI/EMC team with multiple test magnetometers positioned around the component so that a dipole magnetic moment can be determined. Each magnetic source is represented by a magnetic moment magnitude, orientation, and position on the spacecraft.Throughout the build process of the spacecraft on the ground, the EMI/EMC team uses the model to help monitor the aggregate magnetic field at the ECM FG sensors and PIMS FCs and to determine the available mitigation options when large magnetic field sources are encountered Narvaez . Based oIn order to ensure requirements are met, the spacecraft magnetic field model captures the worst-case scenario  since not all dipole magnetic moments from component measurements are readily available during the build process and the orientations of the component’s dipole moments in spacecraft coordinates are usually unknown. At times, the model not only includes the associated magnetic moment extracted from component measurements but also from vendor provided document specifications, subject matter expert estimates from analyses, and heritage design inferences. These estimates include added margin and are built into the spacecraft magnetic field model. To enhance the accuracy of this worst-case modeling and to ensure ECM and PIMS science objectives can be met, spacecraft level magnetic field modeling, visualizations, and Monte Carlo simulations are conducted as discussed in the following sections.As noted previously, due to the large (∼ 30 m) span of the deployed solar panels and the inability to characterize the spacecraft deployment configuration on the ground, simulation is required to ensure that the magnetic field at the senor locations or any points around the spacecraft are within tolerable limits. The magnetic field of the spacecraft, Note that this equation is valid for both DC magnetic field evaluation and the AC field describing moments that exhibit a time dependence, i.e., Of particular interest is the magnitude of the magnetic field around the spacecraft. Using the magnetic moment model and Eq. , an estiAnother informative visualization that can be realized with this magnetic moment model is the magnetic field lines of the spacecraft, representing effective magnetic signature of the 260 sources on the spacecraft. Here, we implement a magnetic field line tracing routine based on the Euler method, also referred to as the first-order Runge-Kutta method. Improved accuracy can be obtained by using higher order midpoint approaches  . Randomizing the magnitude of the magnetic moment is also a possibility but the model already captures a worst-case upper limit for the magnetic moments of all unmeasured components.Figure Figure Vector magnetic field measurements provided by the three, three-axis FG magnetometers will enable the characterization and removal of the stray magnetic field contribution from the Europa Clipper spacecraft and will provide redundancy in the event of sensor failure. Here, we describe the gradiometry approach that will be used by the investigation to disentangle the spacecraft field and the ambient field measured by each of the three FG sensors.The magnetic field measurements 4He atoms. The four sensors produced a total of 14 measurements, a 3-axis vector measurement from each of the four sensors and two absolute scalar measurements from the two helium magnetometers. These measurements were sufficient in number to estimate the 3-element ambient magnetic field vector A full spherical harmonic estimate of the spacecraft field The estimate of the total magnetic field Even though the spacecraft produces a highly multipolar field close to the spacecraft , see results in subsequent section. In this work, to speed up computation time of the Monte Carlo simulations, we initially used the non-linear approach to solve for an average spacecraft dipole offset Two different methods can be used to perform this minimization. One can either (1) use a non-linear least squares approach . However, not all possible combinations of sensor positions are available because of mechanical constraints imposed by the structure of the coilable boom. More specifically, the sensors can be mounted only to relatively static end terminals at the end of each bay, see Fig. In order to assess the optimal sensor positions along the boom and the expected errors of the gradiometry experiment with the mechanically-preferable configuration, we carried out a set of Monte Carlo simulations in which the locations of the middle and inboard sensors were varied along the boom (the outboard sensor remained fixed at the end of the boom) and the DC spacecraft field and the ambient magnetic field were estimated by the gradiometry method outlined previously. We carried out the analysis for a range of spacecraft magnetic field models and instrument noise patterns. . In our analysis, we simulated Figure Using the linear inversion method, additional Monte Carlo simulations were performed to gain a better understanding of how the sensor offset uncertainty affects the errors of the estimated ambient field using a 3-sensor, 2-sensor, and 1-sensor approach. The latter two schemes are included to illustrate the ambient field errors if 1 or 2 sensors happened to fail. These results are illustrated in Fig. The results provided in the previous section collectively demonstrate that the optimal positions of the middle and inboard sensors are determined by a tradeoff between the intrinsic noise and offsets of the instruments, the higher-order moments of the spacecraft field, and the magnitude of the spacecraft field. High instrument noise and large offsets and/or a lower spacecraft field magnitude pushes the optimal position of the two sensors inwards to get a better signal-to-noise measurement of the spacecraft dipole field component. Stronger higher-order moments of the spacecraft field push the optimal positions of the sensors outwards because of the limitations of using a dipolar field model of Eq. . These dAlthough the chosen locations of magnetometer sensors on the boom  are not ideal from a gradiometry perspective, the locations do optimize sensor placement in the presence of mechanical constraints and also result in excellent gradiometric performance for various noise scenarios and scaling of the spacecraft field. The approach described in this work allows us to estimate the impact of such constraints on the magnetic field measurements. For example, even if the offset uncertainty is on the order of +/- 0.5 nT (see panel (c) of Fig. A new magnetic field model of the Europa Clipper spacecraft has been developed and is comprised of 260 different magnetic materials and current-induced field point sources at various locations around the spacecraft. The model is demonstrated to be useful for assessing the magnetic field and its uncertainty at the locations of the fluxgate magnetometer and Faraday cup plasma sensors. Additionally, the model is shown to be useful for visualizing the magnetic field lines associated with the entire spacecraft, which could be used to provide insight into how charged particles may be deflected around the spacecraft and into or away from particle detectors by identifying magnetic mirror points, in addition to visually identifying regions of higher-order magnetic field structure at the locations of the magnetic-field-sensitive sensors. Also shown is the ability to remove spacecraft field from the magnetometer measurements using either a linear or non-linear based gradiometry approach.Although the present magnetic field model is very mature, there are many magnetic material and current sources on the spacecraft that have yet to be fully characterized magnetically. This characterization will be performed on the ground in the next year before launch and is planned to be described in more detail in a follow-on publication. Additionally, the cruise phase of the mission will be essential for characterization and validation of the spacecraft magnetic field model and also characterizing the AC magnetic field sources on the spacecraft. By meticulously turning on individual subsystems or instruments and switching between different modes, we will monitor the associated fields with the magnetometer suite so they can be removed if on during sensitive measurements. While we do not anticipate any of the magnetic field sources on the spacecraft to directly generate AC field signatures at the key periods , some of the components may indirectly create field oscillations at these periods due to Clipper’s 6:1 orbital resonance with Europa. For example, the temperature in the vault, where the ECM electronics will reside, is likely to fluctuate with this resonance due to the instruments and subsystems being more active near Europa. The increased current draw during the Europa encounters will result in increased temperature in the vault causing very small periodic changes in the instrument gain. However, because we’ve characterized the instrument’s dependence on electronics unit temperature, we’ll be able to remove the effect of thermal variation during calibration post-processing. The other AC magnetic field source that is of a potential concern are the currents from the solar array, batteries, PCDA, and loops in the harness connecting these components, likely also able to generate magnetic fields with periods associated with the harmonics of Europa’s orbital resonance. Fortunately, we will also be able to back out this effect from the dataset as their field signature will be characterized during the multi-year cruise campaign. These AC field sources will be difficult to removed and therefore will be addressed in more detail in follow-on publication.Europa_MagneticModel_ConfigF.txt) as supplemental information. Details about how to use the spreadsheet are contained within the document.In this work, we use Matlab for all the data processing and visualizations illustrated in this manuscript. The Europa Clipper spacecraft magnetic field model was captured in a spreadsheet and is available to download as a text file Below is the link to the electronic supplementary material.