Human reliability analysis (HRA) is a major concern for organizations. While various tools, methods, and instruments have been developed by the scientific community to assess human error probability, few of them actually consider human factors impact in their analysis. The active role that workers have in shaping their own performance should be taken into account in order to understand the causal factors that may lead to errors while performing a task and identifying which human factors may prevent errors from occurring. In line with this purpose, the aim of this study is to present a new methodology for the assessment of human reliability. The proposed model relies on well-known HRA methodologies (such as SPAR-H and HEART) and integrates them in a unified framework in which human factors assume the role of safety barriers against human error. A test case of the new method was carried out in a logistics hub of an energy company. Our results indicate that human factors play a significant role in preventing workers from making errors while performing tasks by reducing human error probability. The limits and implications of the study are discussed. Statistics show that human error is one of the primary causes of failure in a variety of working contexts, such as in the nuclear , chemicaRecently, Hou et al.  conducteDespite the success of existing HRA models in increasing safety in many organizations, they still do not adequately consider psychosocial barriers. For instance, among currently available HRA methods, the Standardized Plant Analysis Risk Human Reliability Analysis (SPAR-H) and the Human Error Assessment and Reduction Technique (HEART) are two of the most widely used and acknowledged ,8. Both Therefore, the present paper aims to extend current HRA methods by including psychosocial factors and barriers in a revised framework to analyze human errors in energy companies. The proposed approach is in line with a new scientific trend focused on the inclusion of human factors in quantitative risk analysis . HoweverHEP): task typology (diagnosis or action tasks) and performance shaping factors (PSF), which can be described as the sum of variables belonging to the individual, the environment, and the organization or the task . Although often with some adaptations, the SPAR-H methodology has been used successfully in various energy companies to assess HEP. Mirzaei Aliabadi et al. [HEP of pipeline inspection gauges operations in a gas transmission plant. Abreu et al. [HEP in relation to cascade events in power grid management. However, they integrated the methodology with stochastic simulations using the Monte Carlo methods to increase its effectiveness. Van de Merwe et al. [The overall assumption of SPAR-H, shared with many other HRA methods, is that the occurrence probability of a human error is strictly associated with the typology of the task to be performed and the presence of factors that can positively or negatively influence human performance. Consequently, the method consists of two main components through which it is possible to quantify the human error probability , which, if not controlled, can result in accidents. The model posits that accidents happen when an alignment in the holes of the layers of defense (the barriers) causes the hazard to pass through the defensive lines . DespiteIn line with these developments, Hu  identifiTraditionally, the Bow-tie Model has been used to explain and visualize accidental dynamics in sectors such as aviation and the energy industry . It descIn the following sections, we will describe how the new methodology has been developed, adapting and integrating previous HRA models.HEP in a multinational energy company operating in 68 different countries  with more than 31,000 employees. The HRA method was developed conforming to the theoretical framework discussed above, considering the organization’s characteristics and with the participation of the company’s health, safety and environmental (HSE) managers, researchers, and field experts.The present model was developed to assess The complexity and specificity of the methodology development required us to choose one organization that was sufficiently representative of the entire energy sector. The model includes indicators of safety climate and culture that can influence multiple other factors, highly increasing the complexity of the assessment. Thus, we decided to choose a single organization that would allow us to carry out all of the activities. The developed model can be considered a prototype to be further tested and extended into other organizations. Therefore, the selected organization satisfies a series of requirements that can increase the generalizability of the model to other contexts, specifically: the large number of countries in which it operates; the high number of offices and operational sites; the size of operations; and the large workforce and the wide variety of tasks.To overcome SPAR-H and HEART limitations and to meet organizational contextual needs, an original approach based on the combination of these methodologies was developed. A new assessment methodology including the strong points of both methods was thus obtained. Both methods estimate human reliability according to a given task to be performed. However, while SPAR-H distinguishes between action and diagnosis tasks, HEART provides the possibility to choose between nine GTT. Working tasks in the energy company context are characterized by a high level of complexity and cognitive load. Consequently, determining whether a task is diagnostic or action could be complex and would not allow a specific distinction among the tasks under analysis. Thus, the proposed method introduced a revision of the GTTs of the HEART methodology. The need for a redefinition of GTT derives from Williams and Bell’s study , which rHEP involves the identification of factors affecting performance. While SPAR-H recognizes the role of 10 main PSF, HEART methodology identifies 38 EPC. Due to the necessity of contextualizing the method in the energy company, a revised version of SPAR-H’s PSFs was used in this study since they represent the most efficient categorization of factors affecting performance [The second step required to assess formance . In lineformance , only thTo evaluate the impact of PSFs on human reliability, multipliers of the error probability were associated with each of them, based on evaluation levels. These have been identified through the review of the SPAR-H methodology carried out by Laumann et al. , and theIn the proposed model, human error probability is the product of the interaction between three main elements: the typology of the task to be performed (GTT), the conditional factors affecting performance (PSF), and human factors (human barriers), which are the sum of human and organizational assets of safety preventing workers from performing errors. To identify the barriers to be included in the model, an initial pool of 20 psychosocial dimensions relating to both safeguard and direct barriers were identified through a literature review focused on human factors related to safety in organizations ,39. The The content validity of barriers was established by applying Lynn’s method . A total(1)Dimension’s relevance as a barrier: To assess whether the dimension could be considered as a human safety barrier, the judges were asked the following question: “To what extent do you believe that the psychosocial dimension can positively influence workers’ safety behavior?”(2)Barrier category: To assess whether the dimension could be considered as a direct or safeguard barrier, the judges were asked the following question: “To what extent do you believe that the psychosocial dimension directly prevents workers from making errors during task execution?”The inclusion criteria were the following:A 4-point Likert scale was provided to rate both questions ranging from: 1 = irrelevant; 2 = somewhat relevant; 3 = quite relevant; 4 = extremely relevant. The content validity index for the first criterion was then computed as the number of scores equal to or greater than three for each question (divided for the number of judges).In line with Lynn’s suggestions , only thTo assess the quality of direct and safeguard barriers, an evaluation checklist was prepared. Multiple key indicators representing core aspects and peculiarities of the barriers were identified for each barrier dimension to quantify their quality, concerning their ability to protect operators at work and to prevent errors. For example, the following indicators were defined for safety task performance: “Does the operator work safely while performing the task?”; “Does the operator follow safety norms and procedures related to the task?”.To assess the quality of barriers, indicators in the checklist were associated with different evaluation levels, to which scores ranging from 0 to 1 were assigned. BSd, is calculated for each relevant dimension, as the mean of the scores of the indicators (I) belonging to the specific dimension:dn is the total number of indicators considered for dimension d. A global barrier score for both direct (DBS) and safeguard barriers (SBS) is then calculated as the mean of the barriers scores belonging to each of the two categories:Dm is the total number of dimensions considered for direct barriers and Sm is the total number of dimensions considered for safeguard barriers. Global scores represent the overall quality of both direct and safeguard barriers, and they are used in the HEP estimation process, which is described in the following.A barrier score, HEP is thus carried out in six main steps: (1) determination of the NEP value of the task under analysis; (2) calculation of PSFs multipliers; (3) calculation of direct barriers score; (4) calculation of safeguard barriers score; (5) calculation of conversion coefficient of direct and safeguard barriers; (6) calculation of integrated HEP. The detailed assessment process, including the specific sub-steps of the procedure, is illustrated in The assessment process of HEP assessment requires analyzing the task to be performed and selecting the GTT. Once the GTT is chosen, the assessor identifies the NEP value associated with the specific category of GTT.The first step of the PSFC) as the product of the multipliers of the PSFs:jM is the multiplier selected for the j-th PSF and n is the total number of PSFs considered.The second step involves the evaluation of the PSF associated with the task. To achieve this goal, the assessor may use task observation or interviews to attain all of the information required to estimate the impact of performance shaping factors on human reliability. Once the assessment is carried out, the method requires the identification of the multipliers associated with each PSF and the estimation of the overall impact of PSFs on the probability of human failure through the calculation of the value of the PSF composite  defined for each barrier dimension see . Once thHEP is determined. Global scores of both direct and safeguard barriers need to be converted into new measures representing their impact on human error probability, namely the conversion coefficients. The latter are conceived as multipliers of the HEP (on par with PSF), positively or negatively influencing the occurrence probability of an error. CCDB) and safeguard barriers (CCSB).In the fifth step, the impact of human barriers on HEP is supposed to vary according to the quality of barriers, which can play a preventive role against safety threats, thus decreasing the occurrence probability of errors. In other words, the better the quality of the barriers, the lesser the probability of human error. On the contrary, the poor quality of the barriers corresponds to an increased HEP.As shown in the tables, in line with the assumptions of barriers models ,27 the fHEP based on the global scores of direct and safeguard barriers. Consulted experts were provided with evaluation sheets through which they were instructed to assign a score representing the expected impact of both typologies of barriers on HEP. The average values of the scores were calculated to determine the conversion coefficients.The conversion coefficients for direct and indirect barrier scores reported respectively in HEP:The final step of the procedure (Step 6) involves the assessment of Following the SPAR-H methodology, the probability of human error is the product of the nominal task probability and PSF multipliers. In line with this principle, barriers scores play the same role as PSF multipliers since they impact the probability of human failure.In the following section, a test application of the model is summarized. The test case was carried out in a logistics hub of an energy company. The task selected for the test is lifting operations at a dock. The test was performed by observing a full-scale routine lifting operation during normal functions of the hub.Two assessors were in charge of carrying out the test. The information needed to fill in all of the checklists were gathered preliminarily through three different methods:Documental analysis of organization chart, work permit documents, area risk information, improvement plan, coordination sheets, and schedules. Assessors also had the opportunity to inspect documents regarding policies, procedures, and occupational safety internal reports;Semi-structured interviews with supervisors, managers responsible for operations, site managers, and workers directly carrying out the selected task. A total of 11 online and 10 in-person interviews, lasting around one hour each, have been conducted;One full day on-site direct observations of workers carrying out the task.The logistics hub premises, in which the test took place, served as a hotspot for incoming and outgoing supply vessels from/to offshore gas rigs. Daily, two to three supply vessels load or unload materials and supplies at the dock, using onshore cranes. On the dock, routine operations are governed by established procedures with a one-off generic work permit. No toolbox talks or special (safety-related) briefings are given for this type of activity. Each evening, the contractor foreman receives the vessel arrival schedule for the next day, and the morning after coordinates with the dock supervisor to schedule the daily activities. Special inspections and safety briefings take place in case containers with hazardous substances are loaded or unloaded .It may be concluded that, unless hazardous substances are loaded or unloaded, the task to be performed can be classified as a routinary task, requiring a low level of experience and training. Accordingly, the GTT category chosen for this task was “D”.A contractor team was responsible for carrying out the operations. The group consisted of a foreman (who supervised and actively participated in the slinging and unhooking of loads), a crane operator, and two/three other slingers . The workers’ age range was between 30 and 50 years old, and they all had several years of experience in loading/unloading operations. From the interviews and observations, it was possible to notice that the team was well established and demonstrated particular fellowship and teamwork capabilities.During the assessment, it was possible to observe the loading on a vessel of four medium/small foodstuffs containers, a cage of metallic materials, and a liquid nitrogen tank. The goods arrived at the dock on a semi-tractor-trailer truck. The material was unloaded from the truck by a forklift (the forklift driver and equipment were part of a different contracting company) and placed in a dedicated area near the crane, which was previously closed with barriers and jerseys by the lifting team. The assessors had the opportunity to interview the foreman of the contractors and a slinger before observing the operations. The operations took place on a sunny hot day in July, with an outside temperature of 37 °C.During the observations, it was possible to notice outstanding professionalism and attention to the operators’ safety. However, the following unsafe condition occurred: a container arrived with an incorrectly mounted sling which caused the container to oscillate dangerously when lifted. The operators immediately noticed the problem and tried to disassemble the sling and then reassemble it correctly. After several attempts and a few tens of minutes, however, the operators realized that it was impossible to fix the sling in a reasonable amount of time. According to procedures, the load was not to be lifted using the crane. As stated by organizational procedures, the safest course of action would have been to stop work, request the container to be loaded back onto the truck, and returned to the company to have the sling fixed. Since it was a refrigerated container of foodstuffs, the foreman decided on a different procedure. The load was lifted and loaded on the vessel to connect to the vessel’s power supply, avoiding the deterioration of the contents. The responsible company was then called to fix the problem at a later stage (but before shipping the cargo offshore). An observer asked the safety supervisor, who was present during operations, to stop the lifting given the presence of an unsafe condition. However, the supervisor allowed the lifting operation to be completed before taking action.Two PSFs resulted critical in the assessment: working context and procedure. The working context was evaluated as an “adverse condition” as it was an extremely hot day, and evaluators were firmly convinced that this condition had a significant influence on the decision of the contractor team to act differently from the organizational procedure. The team had to wear protective suits and equipment, highly aggravating the perceived temperature. Furthermore, the hot weather could have influenced the decision since the team was worried about the degradation of the perishable goods in the container that should be refrigerated. Thus, the PSFC was calculated as shown in compliance with safety norms and procedures and safety leadership. Regarding workers’ compliance towards safety, during the observation period, several unsafe behaviors were noticed. According to safety procedures, workers should have stopped the activity when they realized that the container could not be safely lifted. Nevertheless, workers did not stop the activity (first unsafe behavior), then decided to lift the container anyhow (second unsafe behavior). Coherently with this evidence, the key indicators of the barrier were scored as shown in Regarding safety barriers, the scores obtained see  indicateHEP was calculated as showed in Finally, the Historically, HRA methods have focused their attention on the set of factors that can contribute to increasing the probability of human failure. This approach has been tested and validated in many industrial fields and across different organizational contexts. However, current HRA methods fail to consider the role of psychosocial factors and how they may shape their own safety performance . FurtherThe proposed model addresses the recent challenges of HRA methodologies and quantitative risk analysis (QRA) to quantify the impact of the human factor on safety at work . Most ofCurrent models mainly address the analysis of the impact of human factors on specific tasks or events. Zhen et al.  pointed Human reliability is a significant concern in most organizational contexts. Therefore, assessing which factors may impact human performance has become a priority to identify critical areas of intervention and improve workplace safety. The developed approach provides new insights into the role of human factors as safety barriers. Therefore, the results obtained should be thus considered an evolution of our understanding of how safety performance is shaped by contextual and psychosocial factors. Moreover, it represents a useful analytic tool to assess human reliability, analyzing well-acknowledged factors that can affect human reliability and psychosocial dynamics. This allows us to include the positive role that human factors play regarding safety performance.HEP. Future work should consider more extended testing of the model, also considering other working environments.The new HRA method developed still has some limitations. Firstly, to the best of the authors’ knowledge, safety barriers were seldom included in the analysis of human error in previous studies. Thus, this innovative feature of the methodological approach proposed needs to be further tested to establish its general value in predicting Secondly, the safety barriers considered were chosen according to the opinion of a limited group of experts. However, other human factors may affect human performance. Future work should aim at further expanding the model, including different psychosocial factors as safety barriers.HEP needs to be grounded in validated mathematical approaches. Implementing the methodology on larger samples will allow evaluating the impact of each barrier on HEP more.Thirdly, the estimation of


Droplet detachment from solid surfaces is an essential part of many industrial processes. Electrowetting is a versatile tool for handling droplets in digital microfluidics, not only on plain surface but also in 3-D manner. Here, we report for the first time droplet trampolining using electrowetting. With the information collected by the real-time capacitor sensing system, we are able to synchronize the actuation signal with the spreading of the droplet upon impacting. Since electrowetting is applied each time the droplet impacts the substrate and switched off during recoiling of the droplet, the droplet gains additional momentum upon each impact and is able to jump higher during successive detachment. We have modelled the droplet trampolining behavior with a periodically driven harmonic oscillator, and the experiments showed sound agreement with theoretical predictions. The findings from this study will offer valuable insights to applications that demands vertical transportation of the droplets between chips arranged in parallel, or detachment of droplets from solid surfaces. Detaching liquid droplets or liquid separation from solid surface plays an important role in various industrial processes such as self-cleaning , heat trIn applications that require repetitive vertical transport of the droplet between two plates, monitoring the droplet position becomes very important because this information is useful for timing the electric actuation for each droplet. This is most likely carried out by applying electrowetting only in the spreading phase during the droplet’s impacting process with one plate, to avoid conflict between inertia and electrowetting force. Among the various means for detecting droplet position, the capacitive sensor appears to be the most efficient and convenient one. In DMF, capacitance measurement-based droplet sensing was first demonstrated by Gong et al.  and Chen3 or heating the substrate [Although droplet jumping by electrowetting has been extensively studied by various researchers, so far, according to our knowledge, there have been very few reports on trampolining a droplet using electrowetting. Actually achieving droplet trampolining via electrowetting offers obvious advantage over the previously reported droplet trampolining that relies on creating low pressure environmentubstrate ,39,40 toubstrate , we showThe experimental setup  includesU the applied voltage; For systems with the co-planar electrodes, if the gap width dividing the electrodes is much smaller comparing with the size of electrodes, the Young–Lippman equation was then modified to Equation (1) for prediction of the contact angle modulation under a given voltage .(1)η=cocillator ,45,46, a1 (A), when it falls and touches the substrate (electrodes), the pulse (voltage) is applied to the electrodes again (B) to enhance the spreading of the droplet. The pulse continues until the spherical-cap-shaped droplet spreads to its maximum base radius (Rb), and then, the pulse is switched off. This is because under a fixed amplitude of the voltage, a longer pulse does not necessarily lead to a larger spreading of the droplet due to oscillation of the droplet . The actuation cycle is repeated, and the droplet shows a trampolining behavior on the superhydrophobic surface.To realize the mechanism described in According to the energy minimization principle, in experiments employing the co-planar electrodes, the droplet will adjust its position while the voltage is on, so that its base covers a same area of the driving and reference electrodes  formed between the droplet and the electrodes is supposed to scale with the overlapping (footprint) area of the two, and therefore, the capacitor can be conveniently used as a sensor for monitoring the droplet motion, especially for recording the scenario of droplet’s impacting the substrate and the subsequent spreading and recoiling. The moment the capacitor starts to increase indicates touching of the substrate by the droplet (B), and the moment the capacitor reaches its maximum and starts to decrease marks the decrease of the substrate-droplet overlapping area, which also indicates the droplet has started the recoiling process (C). EW are applied to enhance the spreading of the droplet, so in order to avoid the competition between electrowetting-enhanced spreading and inertia driven recoiling, actuation should only be applied when Under such circumstance, the equivalent capacitor  Milli-Q water droplet is deposited on the superhydrophobic substrate, which created a contact angle of ~162° with negligible hysteresis (<4 degrees). Then the plasma-etched substrate surface was characterized using tapping mode Atomic Force Microscopy. The obtained image revealed sharp nanostructures (nano-hills) as shown in A droplet can be detached from a superhydrophobic surface by using AC or DC pulsatile actuations. Similar to the detachment of a droplet upon coalescence ,48, it iIf this additional surface energy overcomes adhesion and friction, the droplet is likely to detach from the solid substrate, and the expected jumping height of the droplet should be approximately~0.85 mm . After tFor the droplet jumping experiment, pulses of different duration were applied. The variation of the droplet jumping height with the pulse lengths was recorded and analyzed , while it experiences a force that is periodically applied during the spreading phase of the impact. Therefore, we adopt the model developed by Schutzius et al.  and descc is the damping ratio. The solutions of Equations (8) and (10) are equivalent toEquation (9) is extracted from the cylindrical model we developed before . By refeWe take ng ratio  and τ′=mF’ according to Equations (1) and (9). Therefore, this part of the work is skipped here. For a discussion on the velocity and acceleration of the droplet, please refer to With the values of In summary, this study has proposed a method for trampolining a droplet on superhydrophobic surfaces using electrowetting. With the feedback information provided by real-time capacitor sensing, we were able to apply EW to the impacting droplet in a precise manner. Since EW pulse is applied periodically in the spreading phase of the droplet, the droplet gains additional momentum after each impact and displays a trampolining behavior. We have modeled the droplet trampolining process using a periodically driven damped harmonic oscillator, and the experiments show sound agreement with theoretical predictions. The active method proposed and the findings from this study will offer valuable insights for applications that demand vertical transportation of the droplets between chips arranged in parallel or detachment of droplets from solid surfaces.


Toe joint is known as one of the critical factors in designing a prosthetic foot due to its nonlinear stiffness characteristic. This stiffness characteristic provides a general feeling of springiness in the toe-off and it also affects the ankle kinetics. In this study, the toe part of the prosthetic foot was designed to improve walking performance. The toe joint was implemented as a single part suitable for 3D printing. The various shape factors such as curved shape, bending space, auxetic structure, and bending zone were applied to mimic human foot characteristics. The finite element analysis (FEA) was conducted to simulate terminal stance (from heel-off to toe-off) using the designed prosthetic foot. To find the structure with characteristics similar to the human foot, the optimization was performed based on the toe joint geometries. As a result, the optimized foot showed good agreement with human foot behavior in the toe torque-angle curve. Finally, the simulation conditions were validated by comparing with human walking data and it was confirmed that the designed prosthetic foot structure can implement the human foot function. In the United States, approximately 600,000 individuals had major lower-limb amputation in 2005, and this number is estimated to reach twice by 20502. Therefore, the design of prosthetic foot has been widely studied for the lower extremity amputees in the past years. The common goal of prosthetic foot design is to mimic the human gait as closely as possible without causing discomfort to the user4. The earliest prosthetic foot model is a solid ankle cushioning heel (SACH)6. The SACH foot consists of a wedge and an internal keel without ankle articulation. Although the SACH foot allows the forefoot to flex, it has several disadvantages due to inflexible rigid keel: poor shock absorption, poor energy release, and user discomfort. To solve these problems, many researchers have developed articulated foot or energy storing/releasing foot that can generate a more human-like foot motion9. Specifically, the powered prosthetic foot capable of controlling ankle joint stiffness is widely studied9. Compared to the ankle joint, however, the toe joint has less highlighted to achieve a human foot characteristic for the prosthesis. To date, the conventionally developed prosthetic feet usually consisted of a single part in the forefoot, which is far from the segmented human foot with toe joint. The toe joint is one of the critical factors in designing a prosthetic foot since the toe joint stiffness affects the ankle kinetics and provides a general feeling of springiness during toe-off11. It is because the toe joint modulates the stiffness by changing the foot arches, which is called the windlass mechanism13. By this mechanism, the foot becomes elastic at the heel-off, providing a natural foot-rolling and a load transfer, and stiff at the toe-off, helping the kicking motion. Therefore, it is important to understand how the toe joint affects gait behavior and how to implement it. Several attempts were made to investigate the toe joint in the prosthetic foot design15. Zhu et al. developed the prosthetic foot with the powered ankle and toe joint to investigate the effect of toe joint on the ankle kinetics. The ankle and toe joint were implemented by using series elastic actuators and they found that adding the toe joint could reduce the energy consumption in the prosthetic foot10. Honert et al. implemented the ankle and toe joint by using die springs and 1095 steel cantilever springs. They summarized that the toe stiffness had a lot of influence on the center-of-mass push-off dynamics, but the toe shape showed a slight effect on it11. Glanzer et al. developed the variable stiffness foot through the leaf-spring rollover structure. As a result, human subjects testing has shown that greater energy storage and return could be obtained with a lower stiffness setting14. All of these studies attempted to mimic the human gait behavior by implementing a human-like toe joint in the prosthetic foot.Worldwide, over hundred thousand people lose their limbs due to diseases such as cancer and diabetes, as well as violence and car accidents each year15. To mimic the toe stiffness change of healthy human during the gait cycle  parts to implement the toe joint which is directly related to the weight increase21) by using short carbon fiber reinforced polymer (onyx) to mimic human foot characteristics, especially the toe stiffness. The finite element analysis was conducted for the various toe joint geometries to simulate terminal stance from heel-off to toe-off. Then, to find the structure with characteristics similar to the human foot, the optimization was performed based on the toe joint geometries. Finally, simulation results such as toe/ankle kinematics, and COP were compared with human data to validate the FEA conditions.In this study, the toe joint behavior was investigated during terminal stance to improve walking performance as shown in Fig. 22. The dimensions were previously implemented to the foot of a custom-built powered prosthesis, AMPRO 2, shown in Fig. 17. To mimic human foot movement and toe characteristics during walking, the different toe shape was applied as shown in Fig. 20. Therefore, it is suitable to use the re-entrant structure to prohibit the load concentration at toe tip, and to protect the part from impact loading. The unit cell of re-entrant structure and its four geometry parameters were depicted in Fig. 20.The prosthetic foot geometry is shown in Fig. To avoid interference between the structures, the bending space (BS) was located behind the last unit cell see Fig. d,e.18, human toe flexion reaches more than 21. The BZ was designed with a curved structure on the inner and outer surfaces of the BS. It allows bending deformation to occur stably without unnecessary plastic deformation of the curved parts and material saving when it is manufactured.According to Zhu et al.entclass1pt{minima24. For the simulation model, the mesh size was assigned to 0.6 mm so that three or more elements exist in the re-entrant structure25. For 3D printing, the onyx was considered which is produced by Markforged. Because Onyx is a short carbon fiber reinforced nylon filament, it has higher mechanical properties than the conventional plastic 3D filaments. Therefore, the tensile strength and the elastic modulus of the onyx were set to 38 MPa and 1.4 GPa, respectively. The simulation was conducted considering only the elastic properties, because it is assumed that the deformation occurs within the elastic region. During the gait cycle, repetitive deformation occurs in the prosthetic foot, and if deformation occurs in the plastic region beyond the elastic region, it cannot be recovered to its original shape. In this study, the terms heel-off (HO) and toe-off (TO) were newly defined in order to broadly deal with the behavior of the toe joint. HO means the state when the toe joint is completely flexed after the heel has already lifted off the ground. And TO means the state when the toe lifts off the ground after the push-off. In addition, a load criterion that the prosthetic foot can withstand in the predefined stance phase is also required. Therefore, the vertical ground reaction force during the human gait cycle was considered. Two maximum load peaks appear on the vertical ground reaction force graph during human walking. The first peak load is the impact force generated by the heel, and the second peak load represents the propulsion force that lifts the forefoot off the ground27. Therefore, considering the stance phase , fracture or any failure should not occur in the designed prosthetic foot under the second peak load condition. In the case of an adult male with the weight of 100 kg, the second maximum load appears to be around 1000 N. This value is set as the load criterion for the foot design28. To simulate the stance phase of human gait, a rigid plate was placed at The mechanical behavior of the prosthetic foot during the stance phase was analyzed with the numerical simulation using commercial software ABAQUS/Standard. The prosthetic foot geometry was given in the simulation as Fig. 18. The point, where the bending space ends, was set as the reference point (O) , which is a classical genetic algorithm proposed by Deb et al. in 2002, was used for solving the given optimization problem31. This algorithm simultaneously optimizes each objective without being dominated by any other solution, unlike the single objective optimization algorithm.The optimization algorithm was used to find an optimal structure of the prosthetic foot. The prosthetic foot should have variable stiffness, which is in accordance with human biomechanics as shown in Fig. The simulation was performed automatically by using MATLAB  to proceed with the optimization. The flow chart of the optimization process is shown in Fig. 18. In addition, the maximum toe flexion was only 18. This is because a large amount of the load is concentrated on the toe tip during the toe-off simulation, rather than moving from the center of the foot to the toe tip as shown in Fig. To investigate the effect of the toe with the re-entrant structure on the toe characteristics during walking, the toe-off simulation was performed for Type 1 and Type 1S Fig. b,d and tCompared to Type 1, the maximum toe flexion angle was increased by 4 times, and the maximum toe torque was reduced by almost half (The toe torque of the curved foot is still high compared with the human foot. This is because the current shape of the bending space has a limitation of the bending deformation as mentioned before. Therefore, to enhance the bending characteristics of the foot, the BZ was adapted in the bending space of Type 2S, resulting in Type 3 (see Fig. 21. Also, the curvature of the bending zone reduces unnecessary plastic deformation and structural damage. That resulted in the decrease of maximum stress and torque loaded on the structure.To visualize this numerically, the maximum toe toque and the toe angle were derived from the torque-angle graph and compared with the result of the curved structured toe as shown in Fig. 33. As shown in Fig. Although the characteristics of the current design are still far from that of the human foot see Fig. a, the re32. In addition, it was confirmed that the toe torque-angle curve of the optimized design has an almost similar curve to the human foot and the load point moved well from the center of the foot to the toe tip as shown in Fig. Since the structure in the toe joint should have nonlinear stiffness characteristics without exceeding the yield strength, the objective functions were set as minimizing maximum stress loaded on the foot and maximizing To analyze the effect of the design variables, object function results according to the design variables were plotted from the Pareto optimal solutions: Fig. see Fig. , a more Since the bending characteristics of the toe joint are mainly determined by the bending zone, the dimensions of the bending zone have more influence on the Therefore, it is essential to select appropriate dimensions of the BZ to implement the nonlinear characteristics of the toe joint and to reduce maximum stress. Consequently, an appropriate design for the characteristics of the human foot was established based on the influence of each design variable from the optimization process.34. Firstly, the GRF according to the COP was analyzed between simulation results and human data. During the stance phase of human walking, the GRF started to decrease slowly when heel-off was performed, and then the GRF more rapidly decreased as the COP decreased as shown in Fig. 36. And, unlike human data, fluctuations in GRF values were found in the last period of the stance phase in the simulation result. This behavior is due to the gap between the re-entrant structure in the toe part. Nevertheless, it can be seen that the graph shows almost the same trend as shown in Fig. So far, the simulation was conducted to analyze the toe characteristics in the stance phase. To simulate the human’s stance phase, the ankle part of the foot was constrained and the force was applied by a rigid plate assembled mentclasspt{minimamentclasspt{minimamentclasspt{minimaBecause the ankle joint was not designed in this simulation, the exact ankle angle could not be directly compared to that of human. However, the tendency of the ankle torque-angle curves was similar based on the normalized ankle angle, and the maximum torque value showed good agreement with the human data. Therefore, it could be concluded that the loading and boundary conditions used in FEA were suitable for simulating human walking.The 3D printable foot structure of this study will be of great help in the rehabilitation treatment of patients. However, there are some limitations to this designed foot. First, the stiffness curve of the designed foot cannot be discrete. Since the designed foot was composed of a single part without additional joints, it is difficult to cause a rapid stiffness change. Due to this, the 3D printed foot shows continuous changes in stiffness unlike human foot with toe joint. Next, the user’s weight, who will use the 3D printed foot, could be limited. The currently designed foot has a stiffness that could only be applied to a specific weight range of patients. Therefore, in the case of patients who are out of the weight range, such as much lighter or heavier people, the dimension of the foot structure must be adjusted. Consequently, it was confirmed that the nonlinear behavior of the human toe joint can be implemented. Based on the result of this study, a designed prosthetic foot will be manufactured through 3D printing technology using the onyx filament. After that, we plan to verify the analysis results conducted in this study through an in-door experiment using the 3D printed prosthetic foot. In addition, it is necessary to design the heel part considering the shock absorption occurring in the heel strike, which is the starting stage of the stance phase. Therefore, in the end, it is planned to expand the design of the prosthetic foot that can stably mimic the nonlinear human gait behavior in the entire stance phase.In this study, the prosthetic foot design was conducted to improve gait performance similar to that of human walking. Then, the mechanical behavior of the designed foot was analyzed through FEA. The bending space with bending zone and the auxetic structure were applied to reduce the toe torque. As a result, the nonlinear toe stiffness behavior was implemented through these toe shape. Furthermore, toe deformation with more than


During the training phase of the supervised learning, it is not feasible to collect all the datasets of labelled data in an outdoor environment for the localization problem. The semi-supervised transfer learning is consequently used to pre-train a small number of labelled data from the source domain to generate a kernel knowledge for the target domain. The kernel knowledge is transferred to a target domain to transfer some unlabelled data into the virtual labelled data. In this paper, we have proposed a new outdoor localization scheme using a semi-supervised transfer learning for LoRaWANs. In the proposed localization algorithm, a grid segmentation concept is proposed so as to generate a number of virtual labelled data through learning by constructing the relationship of labelled and unlabelled data. The labelled-unlabelled data relationship is repeatedly fine-tuned by correctly adding some more virtual labelled data. Basically, the more the virtual labelled data are added, the higher the location accuracy will be obtained. In the real implementation, three types of signal features, RSSI, SNR, and timestamps, are used for training to improve the location accuracy. The experimental results illustrate that the proposed scheme can improve the location accuracy and reduce the localization error as opposed to the existing outdoor localization schemes. The location-based service (LBS) technology is very useful in many IoT-based location-aware applications ,3,4,5,6.The LoRaWANs technology  has the Because the LoRa signals often go below the noise floor after penetrating barriers, the received signal is more sensitive to noises, interferences, and obstacles and hence the RSSI resolution or sensitivity of the path-loss might not be sufficient for outdoor localization. Therefore, RSSI, SNR, and timestamps are all considered as the input data for training so as to improve the accuracy of localization in the proposed scheme.It is shown that the accuracy of localization in LoRa can be improved by machine learning technologies . The macThe deep learning is the application of artificial neural networks to learn tasks which contain more hidden layers. In deep learning, each level learns to transform its input data into a slightly more abstract and composite representation. The deep learning architecture is constructed with a greedy layer-by-layer method. The depth in deep learning is the number of layers through which the data are transformed. The learning architecture with many hidden layers is called as the deep neural network (DNN). The DNN  simulateTo improve existing localization works, we propose a novel outdoor localization scheme using a semi-supervised transfer learning for LoRaWANs. The semi-supervised DNN is used to derive the regression of the estimated location. The semi-supervised transfer learning is adopted because it is not feasible to collect all the labelled samples in an outdoor environment and the accuracy of the semi-supervised transfer learning is usually better than that of the unsupervised learning. The LoRaWAN technology is adopted in this paper because the LoRaWAN technology is one of the communication technologies that is usually used in the outdoor environment for IoT devices. With the low cost and long range characteristic of the LoRaWAN technology, a large area can be covered by very few gateways and hence the hardware cost can be greatly reduced.In this paper, a novel grid segmentation scheme is proposed so as to generate a number of virtual labelled samples by figuring out the relationship between labelled and unlabelled samples. With the labelled-unlabelled samples relationship, we may repeatedly fine-tune our target model by adding more new virtual labelled samples so as to derive more accurate regression and achieve high localization accuracy. In short, the goal of this paper is to reduce the hardware cost of the outdoor localization for IoT devices and improve the localization accuracy of the existing works based on LoRaWANs. The experimental results illustrate that the proposed scheme effectively improves the average accuracy up to 91% in a large experimental area, and may reduce the average localization error up to 4 m in a small experimental area, compared with the existing outdoor localization results based on LoRaWANs.The rest of this paper is organized as follows: Some localization results are shown in This section introduces three classes of existing localization results ,21,22,23Firstly, some localization results are reported for long-range IoT networks or LoRaWANs ,6,13,14 It is not easy to provide accurate localization results by using LoRa because of the following reasons. First, since the LoRa signals often go below the noise threshold after penetrating barriers, the localization based on received signal strength (RSS) and RSS indicator (RSSI) is vulnerable to low signal-to-noise ratios (SNRs) . Second,Some supervised learning-based localization techniques are presented ,17,18,19The transfer learning technique is recently investigated in ,9,10. PaIt is noted that localization results using the semi-supervised transfer kernel learning are developed in ,21,22,23As we know, there are only a few results investigating the outdoor localization by the semi-supervised learning technique. Most of the existing semi-supervised learning results are based on WiFi signals  or WiFi-The main problem is subdivided into two. the first problem is that the research about semi-supervised deep neural network positioning is mostly used in indoor environments. The second problem is that the accuracy of the outdoor positioning for LoRa is not high according to the related literature reviews of LoRa localization ,3,4. ComThis section describes the system model, the problem formulation, and the basic idea in The system architecture of LoRaWAN-based localization with the semi-supervised learning is given in X denote as a database, which includes n samples. Letting i-th sample, including k data from g gateways during a period of time T to collect RSSI, SNR, and timestamps xi=[S2. During the normalization layers  is a non-symmetric measurement of the divergence between two probabilities of the embedded instance, which is between the source domain and target domain (denoted as n labelled points (denoted as The source domain grid segmentation phase is shown in S1. f). The labelled point, the corner point, the boundary point, the kernel point, and their corresponding features are denoted as Each labelled point has a corresponding feature  denoted as S, and multiple parameters  denoted as M.This section describes the environment configuration, setting of parameters, and experimental results. The experiments are performed in the campus of National Taipei University (NTPU). The campus is divided into small area  and small area (SS) are shown in The location accuracies with different epochs, scenarios, and number of labelled samples are shown in As the epoch increases, the localization accuracies of the proposed scheme also increase because more epochs of training can achieve higher accuracy of training results and hence the localization accuracy increases. The iterations of epoch do not affect the localization accuracies of the two SVM based schemes because the two SVM based schemes are not based on the deep learning architecture. The localization accuracies in the environment of LS with multiple parameters and 15 labelled points are the best because, in such environment, the labelled points are closer to each other and more parameters can achieve more accurate training results and thus the localization accuracies are the highestThe location accuracies with different number of iterations are shown in The CDF of localization accuracies in the scenarios of large area (LL and LS) and small area (SS) are shown in A novel grid segmentation localization scheme using a semi-supervised transfer learning for LoRaWANs is proposed in this paper. The proposed scheme uses three signal features, RSSI, SNR, and timestamps, for training and learns grid segmentation knowledge from the source domain and transfer the knowledge to the target domain. A number of virtual labelled samples are generated by figuring out the relationship of labelled and unlabelled samples. With the labelled-unlabelled samples relationship, the target model is repeatedly fine-tuned by adding more new virtual labelled samples. The proposed scheme is implemented on the campus of National Taipei University. Experiment results show that the proposed scheme can decrease the localization errors and improve the location accuracies in an outdoor environment for LoRaWANs. The proposed localization scheme using semi-supervised transfer learning with grid segmentation can also be implemented in other wireless networks based on other deep learning architectures .


Objective: Our objective is to explore the effect of applying cloud video conferencing methods to the informed consent process in an early-phase clinical trial during the COVID-19 pandemic.Methods: All participants who intended to participate in the trial were informed via a cloud video conference before signing the informed consent forms (ICF). Then, the attitudes of the participants with the cloud video conference and their understanding of the trial were evaluated using a questionnaire when they visited to sign the ICF onsite.Results: A total of 165 subjects participated in the cloud video conference process, and 142 visited the site to sign and date the ICFs at the center during the appointment time. The survey showed that nearly 100% of the subjects evaluated the video-based informed consent process as very good or good and gave correct answers to questions about the trial. Furthermore, 136 (95.8%) subjects believed that the knowledge about the trial derived via the video-based informed consent process was consistent with the onsite reality, and 139 (97.9%) subjects expressed their willingness to participate in an informed consent procedure undertaken through an online video conference.Conclusions: The video-based informed consent process achieved the same effects as an onsite informed consent process. The former saves time and cost of transportation for the subject and exhibits good public acceptance; especially in light of the COVID-19 pandemic, this process is conducive for reducing the risk of subject infection due to travel and would also help avoid crowding on site. Informed consent is a fundamental measure to protect the rights and well-being of the subjects in clinical trials. Before starting a trial, researchers must inform potential subjects about the trial, and the potential subjects who agree with the trial procedures are then required to sign an informed consent form (ICF), as per the guidelines of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH), 2016. The current widely used approach for obtaining informed consent involves a face-to-face explanation and discussion between potential participants and trained research personnel, usually the doctor. For early-phase clinical trials, the number of healthy participants is usually more than 6 but fewer than 100. However, the investigator needs to screen more volunteers  to make sure that enough eligible subjects meet the inclusion and exclusion criteria of the trial protocol. Therefore, several potential participants are usually invited to the Phase I clinical trial site on the same day and given detailed explanations for nearly 1 h regarding the informed consent form together as a group of 30 to 50 individuals, followed by a one-on-one discussion with the investigators before signing the ICF. However, gathering the potential participants on-site does not meet the requirements of the COVID-19 pandemic prevention and control. To control and prevent the spread of the virus and ensure smooth conduct of clinical trials and the safety of both health professionals and subjects, a real-time, remote approach telemedicine technology to inform participants should be considered before one-on-one ICF signing is executed. Welch et al. reported in 2016 that the informed consent process embedded into a telemedicine session with remote video conference can eliminate challenges related to the travel and management of personnel at remote sites and improve research recruitment by reducing barriers related to informed consent while preserving human interactions .In the era of social media, nearly every adult owns one smartphone and uses the Wechat APP in work and life. Due to the impact of the COVID-19 pandemic on work and life, video conference APP software has risen rapidly in popularity, such as the Tencent Meeting App. This could make the real-time and cloud video conference in the group context feasible, making it possible to avoid gatherings and help control the spread of the virus.In the traditional informed consent process, the written material provided to potential research participants requires much reading and does not take into account other forms of learning .The purpose of this study was to examine a new approach for the informed consent process through the use of a real-time cloud video conference technique to test its acceptability to potential healthy subjects, and their comprehension of the real-time cloud video-based informed consent process; the method was applied to an early phase clinical trial during the COVID-19 pandemic, and the overall quality and effect of the video conference-mediated informed consent process was evaluated.This study was conducted in connection with a bioequivalence trial testing oral tablets for Parkinson's disease performed in healthy volunteers in a Chinese Phase I clinical trial center from March 31 to May 12, 2020. It was approved by the ethics committee of Aerospace Center hospital. According to the sample size of the bioequivalence trial, the estimated sample size of this study is about 150, which could meet the requirement of cross-sectional studies.The third-party company specifically recruited volunteers from the public or their database of history volunteers by posting the recruitment advertisement through Social Media (like Wechat APP) or the internet. Potential participants were invited to join a cloud video meeting hosted by the investigator through the Tencent Meeting App in a group informed consent process when they intended to participate in the bioequivalence trial or just to be of curiosity without any incentives. Applicants that registered and accepted to participate this way subsequently took about 5 min to be trained by one or two recruitment staff on how to use the application software. The research doctor investigator would explain the ICF and relevant information about 1 h into the video meeting for fewer than 60 people due to the capacity of the software requirement. After being given sufficient time to consider the trial, at least overnight, applicants were offered an appointment to visit the study site in person for a face-to-face informed consent process meeting. Participants eligible for the study were asked voluntarily to fill a questionnaire designed to evaluate the effect and quality of the video-based informed consent process.The study involved the following steps: (a) preparation of the manual of the software application tool (Tencent Meeting App) and training of investigators and registered potential subjects for operating the software; (b) preparation of the newest ICF text and development of the document with pictures and videos to be shown during the meeting; the document covered the trial schedule, related hospital regulations, the seven-step hand-washing method in a graphical form, the protection measures to be taken at home or while traveling in a graphical form, some videos of special procedures and environment introduction, etc.; (c) gathering the potential participants to log in the video conference and testing signal and network quality upon roll call; (d) undertaking of the online informed consent process for about 1 h by one doctor investigator through the cloud video group meeting to explain the above document. As the researcher scrolls through the document and selects text or video, all these materials are updated in real-time on the participant's screen; (e) sends an eICF copy to potential participants and provides an explanation for those with bad bandwidth by phone after the video conference; (f) preparing a self-developed questionnaire by 10 authors regarding the participants' demographic information, evaluation of the effectiveness of the cloud video meeting, and understanding of the ICF of the trial project; (g) the questionnaires were answered by the participants onsite during the appointment time;(h) evaluation of the effect of the remote cloud video meeting through the analysis of the questionnaires when participants visit the study site in person to sign the ICF forms; and (I) holding one-to-one discussion between the investigator and one subject to ensure the effectiveness and quality of the informed consent process. During the one-on-one discussion in person, the investigator asked questions to further assess the effect of the video-based informed consent process and determine if subjects needed to be given further information and explanation about the ICF before the one-to-one signing of the ICF during the consent process in a private room to protect the privacy and confidentiality of their questions.The questionnaire comprised five sections: (a) an informed consent introduction on the front page (b) sociodemographic characteristics, including age and gender, (c) evaluation of the cloud video meeting effectiveness, including yes or no questions according to the previous experience, perceptional effectiveness, willingness to participate again, satisfaction with the informed explanation of doctors and whether it was easy to understand, multiple-choice or open text questions for the points focused on ICF advantages and drawbacks of video-based informed methods, and one ranked-options question for the overall evaluation of the video-based informed process, and (d) evaluation of the understanding of this ICF by testing the ICF content.Data were entered into an Excel database by one staff member and double-checked by other personnel. Frequency distributions and simple descriptive statistics were used to describe the subjects' general characteristics, to evaluate the video-based informed consent process, and to analyze the participants' understanding of the informed consent form by SPSS (version 16.0). Categorical variables are expressed as numbers and percentiles.In this study, 165 subjects participated in the cloud video-based informed consent process together with a medical investigator through the Tencent Meeting App. Subsequently, 142 subjects visited the study site and agreed to complete the questionnaire survey about the cloud video-based informed consent process and sign the written ICF before the trial screening. Participants were 18 to 46 years old with males constituting the majority of the participants at 66.2% . Of the The survey about the effectiveness of the cloud video informed process showed that all 142 (100%) subjects evaluated the effect of the video-based informed consent process to be good or very good without a gender difference in statistics; 136 (95.8%) subjects indicated that the effectiveness of the video-based informed consent process was consistent with that of the onsite informed consent process; 139 (97.9%) subjects expressed the willingness to participate in an online video-based informed consent process again. Among them, 94 (66.2%) subjects believed that the video method could avoid crowding and close contact, 109 (76.8%) agreed that it could save time, 42 (29.6%) subjects thought it could save transportation costs, and 30 (21.1%) subjects indicated that the video-based informed consent process was well-illustrated and easy to be understood. However, 31 (21.8%) subjects indicated that the environment was noisy during the video explanation; only one subject (0.7%) thought that the speed of ICF explanation by the research investigator was fast .There were 136 (95.8%) subjects who knew the background of the drug being used in this trial, all 142 (100%) subjects knew the schedule and trial period for participating in this clinical trial, and correctly answered the question regarding the admission day date; all subjects appeared to understand the investigation procedure, possible adverse reactions, and related medical measures taken in this study  and International Conference on Harmonization of Good Clinical Practice Consolidated Guideline (ICH-GCP) stipulate that the rights, safety, and well-being of trial subjects are the most important considerations and should prevail over the interests of science and society. The ethics committee and informed consent form are the main measures to protect the rights of the subjects . At presThe “Guidelines for Investigations on the Use of Electronic Informed Consent” issued by the US Food and Drug Administration (FDA) in December 2016 defined electronic informed consent as “electronic informed consent refers to the use of electronic systems and processes that may employ multiple electronic media, including text, graphics, audio, video, podcasts, passive and interactive web sites, biological recognition devices, and card readers, to convey information related to the study and to obtain and document informed consent” . SubsequDuring special occasions such as a pandemic, avoiding large gatherings and reducing travel risk are effective measures for preventing the spread of infection. In our survey, 94 (66.2%) participants believed that using the means of a video conference avoided the need for crowding and reduced the risk of virus infection. Therefore, the video-based informed consent process is worth researching and promoting as a supplement or an alternative way to onsite group informed consent meetings. In the traditional informed consent protocol, some subjects may give up visiting the study site because of the long travel distance involved and tight schedule. This study showed that the video informed consent method helped to save time and transportation costs for some participants.A study by Sonne et al. , which aHowever, the study indicated some drawbacks because video conferencing needs to transmit information through the internet and thus has higher network requirements, which may not be fulfilled in some areas. Some participants  indicated that the network was unstable during the video conference. This may be due to weak network signals or the absence of wireless devices in the location where some of the subjects lived. Also, the complete informed consent process took about 1 h, and the subjects were required to stay on the video calls throughout the process; this made it necessary to have a high network flow. According to the questionnaire, some subjects reported that insufficient network flow and the chaotic living environment (of the subject) would have a significant negative, moderating effect on the effectiveness of the video meeting. Therefore, it is recommended to inform subjects in advance regarding the prerequisites for having an interrupted, smooth-running video call, which includes the use of a sufficiently good network or wireless device .In the era of social media, nearly every adult owns one smartphone and uses the Wechat APP in work and life. However, video conferences require good network signals and flow, which may be difficult to achieve in remote areas and volunteers with lower income. This study was conducted in a municipal city with good network signals, and the data about drawbacks may therefore be overestimated.When the investigator prepared hardware facilities, informed consent, and trial procedures before the video-based informed consent process and the subjects were subsequently trained for using the Tencent Meeting application and participated in the video conference using a good wireless network, the effect of the video-based informed consent process was similar to that of an onsite process. Video and graphic explanations could enhance the subject's understanding of the content of the informed consent and greatly reduce the subject's transportation cost and time, as well as the manpower and material resources of the research center. Under special circumstances such as the COVID-19 pandemic, a video-based approach can reduce the risk of virus transmission compared with the traditional method. Furthermore, the recording of the video conference during the video-based informed consent process can be stored as evidence for inspection later, if necessary. With the continuous development and maturity of electronic technology, video-based informed consent processes could be used alone or as a supplement to the traditional onsite informed consent process.“Teleconsent” was the term used by the FDA for electronic informed consent. The method reported in this study is different from that of teleconsent since it combines an online (video) and an offline (onsite) process for the acquiring of informed consent. Although it offers many benefits to researchers, some limitations need to be considered before it is utilized for obtaining informed consent during clinical research. First, it requires participants to have access to a computer with a good internet connection. While a large portion of the population will have direct access to broadband at home or the internet through smartphones, not everyone has access to such facilities. Second, the selected remote cloud video meeting should meet the requirement of privacy and confidentiality for participation in the clinical trial, and all the subjects should comply with this requirement so as not to disclose confidential information on trials or subjects.In addition, this study was conducted in connection with a single trial, and the sample size may thus be limited, and potential participants may have specific characteristics. We also did not investigate the 23 participating individuals who did not visit the study site. There may also be evidence of some educational, financial, or other social sampling biases. As a result, their attitudes about the video-based process in the questionnaire were thus useful, and this could be addressed in a future study.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Ethics committee of Aerospace center hospital. The patients/participants provided their written informed consent to participate in this study.ZW, AD, GC, and JW made substantial contributions to the conception and design of this study, to the acquisition of data, and to the analysis and interpretation of the data. ML, SZ, XL, DZ, LZ, and YZ made substantial contributions to the implementation of the study. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Soft tissue tension is treated as a crucial factor influencing the post-THA dislocation. The femoral offset is regarded as one of the major parameters responsible for the stabilization of the prosthesis. It is unclear which soft tissue is mostly affected by the offset changes.A finite element model of the hip was created. The model comprised muscles, bones, a stem, the acetabular component and a liner. The muscles were modelled as a Hill-type musculo-tendon nonlinear springs. Nonlinear analyses of the hip flexion and internal rotation were performed for the two values of the femoral stem offset.We observed that the quadratus femoris and gluteus medius produce the largest resisting moment opposing the external load excreted by the surgeon during the intraoperative hip dislocation test.An increased femoral offset increases the stretching of the quadratus femoris muscle significantly and provides the growth of its initial passive force. This muscle serves as a stiff band, providing stabilisation of the hip prosthesis, measured during the simulated intraoperative test. Total hip arthroplasty (THA) is the most successful and cost-effective procedure for patients with end-stage hip arthritis . SurgicaThe aetiology of instability can be divided into two categories: surgery-related factors and patient-related factors. Patient-related factors are associated with age, sex, height, weight, soft-tissue laxity, previous surgery and neuromuscular impairment . SurgeryIn this study, we used the FEM model to analyse the effect of the femoral offset on the passive tensile reactions of muscles crossing the hip joint in the posterior approach arthroplasty. We did not limit the study to the abductors because the stability of the joint is assumed to also be afforded by other, particularly short, muscles . The motViVA—Virtual Vehicle Safety Assessment: Open Source Human Body Models addressing gender diversity” . Specifically, the results described in [One finite element method (FEM) model of the pelvis, femur and hip joint was created together with the respective muscles and tendons. The geometry of the pelvis and femur was obtained from the project “ribed in  were useThe muscles and tendons are treated as springs whose response is described by the widely used Hill’s type musculo-tendon model –24. DetaE = 850.0 GPa, Poisson ratio v = 0.4, and ρ = 960 kg/m3. The position of the implant relative to the femur and pelvis is shown in The bones, stem and head acetabular component are assumed to be rigid. The liner was modelled as isotropic and linear elastic, assuming the following data: x-axis points distally, the y-axis points laterally and the z-axis points anteriorly. All the rigid bodies described above are assumed as fixed in the simulation. The movement of the femur is controlled by the rotational velocity vector applied at the centre of the femoral head.Following , the maiTo examine the femoral offset influence on the hip stability and muscle tension, one of the practical intraoperative stability tests is simulated , 28. In The model was validated against the experimental data available in the literature. Figs To assess the influence of the offset, the model of the hip in Abaqus was loaded by the rotational velocity first to achieve 90° flexion and then to simulate internal rotation . In the The stability of a hip in THA is assessed during operation in deep anaesthesia; thus, passive muscle reaction is predominant. To our best knowledge, no data are available in the literature concerning passive hip rotation preceded by flexion. Therefore, our validation was based only on experiments performed for passive flexion.The observed agreement between the results produced by the model and experiments shown in The obtained numerical curves in Figs A high offset increases the stretching of this muscle and provides the growth of its initial passive force because of the specific location of the quadratus femoris in the pelvis. The muscle is very short, runs horizontally in the neutral position and is the lowest muscle among the other deep rotators. Consequently, during flexion, the muscle undergoes large elongation—at 90° hip flexion, it extends by half of its optimal length . Thus, aThe study indicates the muscle which strengthening could potentially decrease the risk of the posterior dislocation of the hip prosthesis. The study of the problem will be extended in the future works.This study possesses limitations. The muscles were modelled as nonlinear elastic springs acting in the anatomical direction of the given muscle. The three-dimensional structure of the muscle is not considered; thus, it is impossible to include mutual interactions between the muscles and fascia. Additionally, the muscle does not have transverse stiffness. The pelvis and femur dimensions for a single woman were used, whereas the properties of the muscles were considered as the means, independent of gender.In this work, we have shown for the first time that, during the popular hip dislocation test in the intraoperative manoeuvre from among of all the muscles crossing the hip joint, two muscles, the gluteus medius and quadratus femoris, produce the largest resisting moment opposing the external load exerted by the surgeon. With the increase in the internal rotation, however, the role of the gluteus medius ceases to be relevant. Thus, the quadratus femoris becomes the main soft tissue carrying the load applied to the joint. The increased offset value yields the increased passive muscle force in this muscle. We have shown that the moment causing hip dislocation may be interpreted as the limit point on the internal rotation moment curve.Future studies should address the analysis of active muscles and their influence on the stability during everyday activities.S1 Appendix(DOCX)Click here for additional data file.


Work on controlling the propagation of surface plasmon polaritons (SPPs) through the use of external stimuli has attracted much attention due to the potential use of SPPs in nanoplasmonic integrated circuits. We report that the excitation of edge plasmon by TE-polarized light passing across gapped-SPP waveguides (G-SPPWs) leads to the suppressed transmission of long-range SPPs (LRSPPs) propagating along G-SPPWs. The induced current density by highly confined edge plasmon is numerically investigated to characterize the extended radiation length of decoupled LRSPPs by the TE-induced edge plasmon. The suppressed transmission of LRSPPs is confirmed using the measured extinction ratio of the plasmonic signals which are generated from the modulated optical signals, when compared to the extended radiation length calculated for a wide range of the input power. It is also shown that LRSPP transmission is sensitive to the excited power of edge plasmon in the gap through the permittivity change near the gap. Such a control of SPPs through the use of light could be boosted by the hybridized edge plasmon mode and a huge field enhancement using nanogap, gratings or metasurfaces, and could provide opportunities for ultrafast nano-plasmonic signal generation that is compatible with pervasive optical communication systems. Plasmonic materials, including metals below the plasma frequency, have an inherent ability to squeeze light within deep-subwavelength volumes through the kinetic energy of free carriers inside the material . By virtSPPs are regarded as promising information carriers for the next generation of integrated circuits because a broad range of mode sizes can be realized through waveguide configurations ,10,11 orThe control of the propagation of SPPs with external stimuli has attracted much attention for realizing SPP-based optical isolation, nonreciprocity and signal generation in NPICs. It has been found that drifting electrons using an external electric current ,29,30,31clad = 1.45) and for the 6 × 6 μm2 core (ncore = 1.46) of the channel waveguide. Experiments were performed using 1.550 μm laser diodes. One of them was used to excite LRSPPs with a 20 nm thick input surface plasmon polariton waveguide (SPPW) with the power of 0 dBm, and the other was used to excite polarized optical signals with a variable optical attenuator and a polarization controller. Details on the experimental setup and fabrication processes can be found in [found in ,41. To sx direction and carries an antisymmetric charge density distribution along the central horizontal plane of the waveguide. The excited LRSPP is one of the fundamental modes that is supported by a gold strip and has Gaussian-like field distribution. x). The current density is calculated using finite-difference time-domain (FDTD) simulations. The amounts of other components (Jy and Jz) are minute, due to the fact that Jy contributes to the radiation in higher-order modes [z), proportional to Jz, is significantly small inside the SPPW, due to the electromagnetic boundary condition [The LRSPP excited in the input SPPW propagates along the er modes ; the norondition ,43. At tondition ,40,44,45To investigate why the transmission is lowered by the broadening of the Gaussian beam, the tunneling of LRSPPs across the gap and the coupling of LRSPPs by a Gaussian beam are compared. x-y plane) and accumulates electric charges at the end(front)-facet of input(output) SPPWs. As a result, the light excites a plasmonic mode in the gap. core = 1.46). Most of the fields are highly localized at the edges and the effective index is 1.48737, which indicates that the dispersion curve of the excited mode lies to the right of the respective light line, and an edge-guided plasmonic mode is excited in the gap by the TE-polarized light. x and Jy) are normalized to the amplitude of Jx by LRSPPs (JLRSPP), to characterize the impact on the LRSPP propagation by the TE-induced edge plasmon. Far stronger current densities than that of the LRSPP are induced near the edges, and the symmetry of current density carried by the LRSPP would break if the LRSPP and TE-polarized light were incident to the gap coincidently. Therefore, the LRSPP propagating along the input SPPW radiates by scattering before it reaches the structural interruption (end-facet of the input SPPW). We defined the decoupling length (Ld) as the summation of the gap length and the lengths for which the TE-induced current density is larger than that which is carried by the LRSPPs at the G-SPPWs. Ld represents the extended radiation length by TE-induced edge plasmon. The decoupled LRSPP by the edge plasmon radiates freely for the decoupling length and re-excites LRSPPs at the output SPPW, which leads to the suppressed transmission of LRSPPs by the extended radiation length.We investigated the plasmonic response of G-SPPWs using FDTD analysis in the presence of incident polarized light across the 4 μm gap, as considered in the previous study . When TEz-axis. 2 core of the channel waveguide. Most of the field is distributed in the core with a refractive index of 1.46. The mode profile is almost the same; the fundamental TM mode is excited in the channel waveguide and the effective index is 1.45607, which indicates that a photonic TM mode guided by the core is excited in the gap. On the other hand, TM-polarized light exhibits quite a different response in the gap. The magnetic field of TM-polarized light excited in the channel waveguide oscillates parallel to the planar plane of PSC, and the electric field mainly oscillates in the The suppressed transmission of LRSPPs by TE-induced edge plasmon was investigated experimentally for a wide range of the input optical power in PSC (0~21 dBm). The TE-polarized optical signals were modulated at 3 Hz frequency by the attenuator. edge/Pinput is 1.0084% for the continuous channel waveguides and 0.7867% for the discontinuous channel waveguides. Since the input optical power is the same for both cases, there are significant observable changes in the excited edge plasmon mode. Therefore, it is found that the transmission of LRSPPs across the gap is affected by the TE-induced edge plasmon, depending on the excited power of edge plasmon in the gap. This also explains the reason why a significantly larger input optical power is required to suppress the transmission of LRSPPs in a PSC. Therefore, it would be possible to improve the plasmonic signal generation efficiency by introducing plasmonic nanostructures so that more power is transferred to free electrons in order to excite the edge plasmon and induce a strong electric current parallel to the SPP propagation, reducing the overall power consumption. We also investigated the dielectric effect on the PSC through the discontinuity of the channel waveguide. We performed numerical FDTD analysis and experiments on the plasmonic response in the gap of a PSC with the polarization and power of an input optical signal, and for the discontinuous channel waveguide. The TE-polarized light excites the highly confined edge plasmon in the gap and induces a strong electric current inside the G-SPPWs, overwhelming the surface plasmon wave that is carried by the LRSPP, thereby breaking the symmetry at the top and bottom interfaces of G-SPPWs. The LRSPP decouples to a lightwave before it reaches the end-facet of the input SPPW and the transmission of the LRSPP is lowered by the extended radiation length and increased coupling loss. The decoupling length is defined in order to characterize the extended radiation length of the decoupled LRSPP by TE-induced edge plasmon, compared with the measured extinction ratio of plasmonic signals. For the PSC experiments with a wide range of input optical power, the extinction ratio of plasmonic signals increases with the input optical power, since more power is transferred to free electrons to excite the edge plasmon and a stronger current density is induced to the G-SPPWs, extending the decoupling length. Therefore, induced current density that is parallel to the SPP propagation can affect the propagation of SPPs ,29,30,31We show that the highly confined edge plasmon excited by TE-polarized light passing across G-SPPWs induces strong electric currents, resulting in the suppressed transmission of LRSPPs propagating along G-SPPWs. Considering the plasmonic response for the polarization, the power of the input optical signal and the discontinuous channel waveguide in a PSC, it is found that the extinction ratio of plasmonic signals increases as more power is transferred to free electrons used to excite highly confined edge plasmon. Such a control of SPPs with light could be boosted by the huge field enhancement and hybridized edge plasmon modes offered by nanogaps, gratings or metasurfaces and could provide opportunities for an ultrafast nano-plasmonic signal generation that is compatible with pervasive optical communication systems.