It is known that measurement and extraction of the tiny amplitude of second harmonic Lamb waves are the main difficulties for practical applications of the nonlinear Lamb wave technique. In this study, phase-reversal approaches and phase matching technique are combined to build up the second-harmonic generation (SHG) of Lamb waves. A specific Lamb wave mode pair, which satisfied phase matching conditions, is selected to ensure the generation of cumulative second harmonic waves. Lamb wave signals with the same frequency but in reverse phase, propagating in the given specimen, are added together to counteract the fundamental waves, and simultaneously to enhance the signals of the second harmonic generated. The obtained results show that the phase-reversal approach can enhance the signals of second harmonic Lamb waves, and effectively counteract that of the fundamental waves. The approach is applied to assess the thermal-induced material degradation in the stainless steel plates. Distinctions of the acoustic nonlinearity parameters under different degraded levels are clearly shown in an improved repeatable and reliable manner, while those of linear wave velocity in the specimens are neglectable. The experimental investigations performed indicate that the proposed approach can be taken as a promising alternative for assessment of material degradation in its early stages. Initiation and progression of material degradation accumulated via in-service thermal exposure of industrial components can significantly affect their structural integrity. The accumulation of the material degradation with increasing loads could lead to catastrophic failure without timely inspection and assessment ,2,3. TheThe use of acoustic nonlinear responses in solids is taken as a promising nondestructive testing method for micro-damage detection ,14. InteHowever, it is found that the effect of SHG can be easily overlooked due to the dispersive nature of Lamb wave propagation ,25,26. TPhase-reversal technique  has been widely used to accentuate the contribution of even harmonics, while counteract the odd ones in medical ultrasonic imaging ,28. ReceIn this paper, a phase-reversal nonlinear Lamb wave approach which combines the phase matching and phase-reversal techniques, is investigated to assess the thermal damage in stainless steel plates. A specific Lamb wave mode pair which satisfies the phase matching condition, is selected to generate the cumulative second harmonic waves. The phase-reversal approach for signal processing is used to counteract the primary wave and meanwhile to enhance the signal of second harmonic Lamb wave generated. The phase-reversal nonlinear Lamb wave approach proposed is applied to assess the thermal-induced material degradation in the 201 stainless steel plates. The correlations are presented between the acoustic nonlinearity parameters and the thermal loading time/temperature in the specimens, which show a promising alternative for assessment of material degradation. Material nonlinearity is essentially related to microstructure and/or presence of defects in materials. Interaction of ultrasonic wave with material nonlinearity can cause the waveform distortion of ultrasonic signal, and consequently generate higher harmonics ,16. One u of ultrasonic wave propagation can be taken as the sum of the fundamental wave oz direction, and the corresponding mechanical displacements are only considered in the yz-plane.The acoustic field k and y = h or y = −h), the amplitude of the primary Lamb wave can be set to be A1 (y) ,34,35. SIf we let the phase of primary Lamb wave be reversed with that shown in Equation (2), while letting the other conditions be kept unchanged, similarly, the total field of Lamb wave propagation at the surface of the plate, including the fundamental wave and the second harmonic generated, can formally be given by,By summarizing Equations (3) and (4), it is found that there is only second harmonic remained in the resultant field, i.e.,The above analysis indicates that the signal of second harmonic caused by material nonlinearity for Lamb wave propagation can be enhanced by phase-reversal technique. Only the second harmonic generated remains, while the offset of the two fundamental Lamb waves in reverse phase takes place under the condition of primary Lamb wave propagation in the specimen with material nonlinearity. The mechanism of the phase-reversal approach is intuitively shown in z is the propagation distance. F is a feature function, which is related to driving frequency, mode type, material property and geometric parameter of specimen. Since all these parameters are completely determined for the given measurement of Lamb waves, F can be regarded as a constant. In this investigation, the ratio The acoustic nonlinearity parameter fined as ,35,36,, the phase velocity dispersion curves of Lamb waves are shown in This investigation examines the 201 stainless steel plates with chemical composition shown in Tx), whose nominal frequency is 3.5 MHz, is used to excite a longitudinal wave, and the other piezoelectric transducer (as a receiver Rx) with central frequency of 5.0 MHz is set for detection of primary Lamb waves and second harmonics generated. The transducers are clamped to the acrylic wedges. Light lubrication oil is used to couple the transducers to the wedges, as well as the wedges to the specimen. Although the central frequency of the receiving transducer Rx is 5.0 MHz, the following experimental results have shown that there are still adequate sensitivities near the driving frequency 3.85 MHz and its double frequency 7.70 MHz. The angle of the two wedges can be calculated by Snell’s law, once the phase velocity of Lamb waves  as shown in A2 is slower than that of S2. These two wave packages will distinguish with each other after propagating a certain distance, and the S2 mode will firstly been received. There is only one wave package in time domain because of the separation of two modes due to different group velocities. Thus, we are convinced that the carrier of the signals detected in S2 mode desired. In the following experiments, investigations focus on the mode pair S4 mode at the frequency 7.70 MHz).As shown in above analysis, it is critical to determine the phase matched Lamb wave mode pair for nonlinear Lamb wave measurements. The first setup is to verify that the signal detected is that of the Lamb wave desired. z as shown in Equation (6). z = 50 mm, through which the amplitudes of the primary wave (A1) and the second harmonic generated (A2), as well as z in It is known that the demonstration of the cumulative effect of SHG versus propagation distance is essential for nonlinear Lamb wave measurements ,19,21,22ier work , the sloTx in Rx at z = 30 mm is shown in Tx, and then repeat the same measurement. For this situation, the time-domain signal detected is shown in The effect of the phase-reversal approach proposed in For examining the effect of the phase-reversal nonlinear Lamb wave approach proposed, Aa1) can be obtained from its amplitude-frequency curve (similar to that shown in Ab1) of the other signal. For determination of A1 is calculated through A2 is acquired through the amplitude- frequency curve of the superposition signal similar to that shown in For a given propagation distance, the two time-domain signals similar to that shown in /In the present experimental investigations, different degradations of the specimens suffered from different thermal loadings are artificially controlled see . Using t0MHz see  and follCg) of Lamb wave in the specimens with and without thermal loadings are also provided to compare the sensitivity of linear and nonlinear parameter. It is clearly shown that the differences of wave velocity can be neglected, which indicates that the linear Lamb wave based evaluation technique is insufficiently to evaluate the thermal induced degradation in early stage. In this study, all measured linear and nonlinear parameters are normalized by the values of the raw material to display only the relative change. Consequently, these results indicate that nonlinear ultrasonic parameters are much more promising with significantly improved sensitivity over linear parameters for early stage detection of thermal damages in this specimen.Here the variation of acoustic nonlinearity  in the test specimens are obtained. Distinctions of the relative acoustic nonlinearity parameters for the specimens under different degraded levels are clearly provided. A comparison of the linear and nonlinear ultrasonic parameters variation in different specimens is also conducted. It is found that the differences of linear parameter in the specimens are neglected. The experimental investigations performed indicate that the proposed phase-reversal nonlinear Lamb wave approach can be taken as a promising alternative for assessment of material degradation in metallic specimens. It is important to note that the counteraction of primary Lamb waves and accentuation of second harmonic Lamb waves must be synchronic. Thus, phase and group matching conditions of the primary Lamb wave and second harmonic one should be satisfied precisely to ensure the accuracy of the obtained results. In addition, stable and consistent electrical signals with opposite phase excited at different times are also important to obtain the accurate results.


Wearable sensors and advanced algorithms can provide significant decision support for clinical practice. Currently, the motor symptoms of patients with neurological disorders are often visually observed and evaluated, which may result in rough and subjective quantification. Using small inertial wearable sensors, fine repetitive and clinically important movements can be captured and objectively evaluated. In this paper, a new methodology is designed for objective evaluation and automatic scoring of bradykinesia in repetitive finger-tapping movements for patients with idiopathic Parkinson’s disease and atypical parkinsonism. The methodology comprises several simple and repeatable signal-processing techniques that are applied for the extraction of important movement features. The decision support system consists of simple rules designed to match universally defined criteria that are evaluated in clinical practice. The accuracy of the system is calculated based on the reference scores provided by two neurologists. The proposed expert system achieved an accuracy of 88.16% for files on which neurologists agreed with their scores. The introduced system is simple, repeatable, easy to implement, and can provide good assistance in clinical practice, providing a detailed analysis of finger-tapping performance and decision support for symptom evaluation. Wearable sensors and advanced algorithms are increasingly being used for the development of new clinical support systems for more efficient diagnostics and the evaluation of symptom severity and disease progress in Parkinson’s disease (PD) . This coBradykinesia is one of the main manifestations of PD. It is evidenced as slowness of body movements, especially in tasks that require fine motor control . In clinIn the literature, different approaches are presented for the objective evaluation and quantification of PD motor symptom severity, including bradykinesia. The introduced methodologies differ in terms of applied instrumentation, analysed movements, measurement protocols, the size and composition of patients’ groups, and implemented signal processing and learning techniques. Some studies implement RGB or infrared camera systems for measuring clinically important repetitive hand and leg movements ,11,12. AIn the literature, bradykinesia is assessed by analysing different repetitive movements, including finger-tapping ,13,21, hr=−0.80) . Signalsr=−0.80) . It is sA methodology that combines principal component analysis and multiple linear regression is applied to quantify bradykinesia severity in FT movements . The metIn order to describe bradykinesia in multi-joint upper limb movements, researchers have introduced new performance indexes that are correlated with UPDRS bradykinesia scores and implemented for differentiation between PD patients with and without bradykinesia . A similAlthough supervised machine learning algorithms provide prediction of clinical scores with high accuracy, the applied models are trained on a smaller dataset with subjectively defined data labels, which may cause subjectivity in the results as well. Because of that, some researchers have introduced different approaches to this topic. Decision rules can be designed to match exactly the criteria of the decision-making process and instructions applied in clinical practice. Fuzzy rules were applied for prediction of clinical scores using inertial data recorded during foot tapping  and handIn this paper, we propose a new decision support system for the provision of clinical scores based on the use of inertial data describing finger-tapping movements. The proposed system uses novel metric and decision rules that are especially designed to capture and evaluate the relevant characteristics of the finger-tapping movement. The system provides very good results for data obtained from patients with idiopathic Parkinson’s disease but also with atypical parkinsonism. The output of the system comprises the kinematic features describing the finger-tapping performance, a graphical presentation of the recorded data with marked irregularities, and important changes in the signal and bradykinesia severity scores.The used system comprises two miniature (10 × 12 mm) and lightweight inertial sensors with three-dimensional (3D) gyroscopes L3G4200  positioned over the fingernails of the thumb and index finger, as shown in Fifty-six subjects were recruited for this study from the Clinic of Neurology, Clinical Centre of Serbia, Belgrade. The subjects included 13 patients  with idiopathic Parkinson’s disease (PD), 17 patients  with atypical parkinsonism multiple system atrophy (MSA), 14 patients  with atypical parkinsonism progressive supranuclear palsy (PSP), and 12 healthy controls (HC) . The patients were tested during their “off” phase . Descriptive statistics (average ± standard deviation and median) of the clinical data for each group of subjects are presented in During the recordings, the subjects were sitting in the chair with their arms bent and supported at the elbow and hands placed in front of them. They were instructed to perform the finger-tapping test by tapping their thumb and index finger as quickly and as widely as possible for 15 s. Although instructions provided in the UPDRS test state that patients should tap their fingers 10 times , in thisIn order to become accustomed to the instrumentation and measurement methodology, for each subject, several trials were recorded per hand, with one minute of rest between the trials. Each trial was also recorded with a video camera, which filmed the hand in a close-up view. The most representative recording (one for each hand) was used for further analysis. The recording was selected by the neurologists as the recording that fullfills the requirements of tapping duration and patients’ understanding of the given instructions. The testing of each subject was performed during one day at the Clinic of Neurology, Clinical Centre of Serbia, Belgrade. The examination was carried out in accordance with the ethical standards of the Declaration of Helsinki, and approved by the Ethical Committee of the School of Medicine, University of Belgrade. All of the participants provided informed consent prior to participation in the study.The recorded video data were later examined and scored by two neurologists with more than 10 years of experience, based on their knowledge and experience and the instructions given in the UPDRS, Part III–Motor examination, task 3.4 Finger tapping. The neurologists were blinded to the subjects’ identity, since the video data show a close-up view of each subject’s hand. The scores were given for each patient, separately for the left and right hand. The scores given by neurologists are provided in The gyro data were recorded with a sampling frequency ch other . The angω1 →−ω2→ . The domanalysis . It was Further analysis was divided into one pre-processing block for segmentation to individual taps and four blocks that calculate features to describe criteria defined in the UPDRS test: tapping amplitude, amplitude decrement, hesitations and freezes, and tapping speed. The calculated features are then used as the input to the decision-support system. As the result, a complete analysis of the patient’s finger-tapping performance, including the finger-tapping score (0–4), is provided.In order to evaluate characteristics of the tapping performance for individual taps, segmentation of the dominant component of the relative angular velocity circles, , whereascircles, . The samcrosses, .One of the evaluation criteria is the tapping amplitude, which evaluates how widely subjects can tap their fingers. The finger-tapping amplitude is defined as the angle that fingers formed during repetitive tapping movements. The tapping angle was calculated by integrating the dominant component of the relative angular velocity ωrd . The driPhysicians evaluate the amplitude decrement according to the part of the tapping sequence at which the amplitude starts to decrease. In order to objectively quantify changes of the tapping amplitude, we observed tap-to-tap changes in the highest finger apertures calculated for individual taps Hesitations and freezes are manifested as irregularities or breaks of the tapping rhythm that may occur in different moments of the tapping performance and represent an important part of the finger-tapping evaluation. The continuous wavelet transform (CWT) was applied for the detection and localization of disruptions of the tapping rhythmicity . It is af0 = 1 Hz and time-frequency resolution σ = 0.7). A matrix of complex CWT coefficients was obtained as a result. We introduced a cross-sectional area by summing the CWT coefficients perpendicular to the time axis. The obtained characteristic was normalized with respect to its maximum value and is expressed as a percentage  the regular rhythm is broken with one or two interruptions or hesitations of the tapping movement; (b) slight slowing; (c) the amplitude decrements near the end of the 10 taps.2Mild: Any of the following: (a) three to five interruptions during tapping; (b) mild slowing; (c) the amplitude decrements midway in the 10-tap sequence.3Moderate: Any of the following: (a) over five interruptions during tapping or at least one freeze in ongoing movement; (b) moderate slowing; (c) the amplitude decrements starting after the first tap.4Severe: Cannot or can only barely perform the task due to slowing, interruptions, or decrements.In the UPDRS motor scale, Part III–Motor examination, task 3.4 Finger tapping [Each hand is evaluated separately, in terms of speed, amplitude, hesitation and freezes, and decrementing amplitude. These criteria are described with the introduced features, which are then fed to the decision support system. The input feature set includes the average tapping angle As indicated, the lowest score corresponds to “normal” movements. Therefore, the first step is to find values that could be considered to be the reference for normal movements. The defined methodology was initially applied to a signal database from the control group that included a subset of healthy controls with no signs of bradykinesia (scored with 0). During the examination of the video files, it was noticed that both patients and healthy controls performed the tapping task in two different ways. In the first group, the subjects tapped as widely as possible at the highest speed that allows for such a tapping. In the other group, the subjects tapped with smaller amplitudes, but at their fastest pace. Using the parameters describing the tapping speed and amplitude (The block scheme of the decision support system is presented in To find the agreement between the scores obtained from two neurologists (raters), Cohen’s kappa statistics for finding intra-rater reliability among categorical data were applied. The results obtained from the decision support algorithm were compared with the scores given by the neurologists. The performance was measured using the confusion matrix and the accuracy of the proposed method, expressed as the percent of equally assigned scores. Initially, results were evaluated for all recordings (Case I), and later for the recordings equally scored by both raters (Case II).The intra-rater reliability was calculated with the Cohen’s Kappa statistic and it equals to κ = 0.79, showing some discrepancy between raters’ scores. This result is expected, since the scores are provided based on their visual and subjective estimation. Overall, 87 recordings obtained from 44 patients  were included in the analysis, as well as 24 recordings obtained from 12 healthy controls. The descriptive statistics for the introduced features are given in The highest values for the The results of the expert system are presented in When all recordings are included in the analysis, comparable results are obtained for all three groups of patients. It is shown that the decision support system provides results that agree with the scores of the neurologists with a good accuracy (above 80%). This result is improved when only recordings equally scored by both raters are included in the analysis, achieving nearly 90% matching between the system results and neurologists’ estimates.The scores evaluated by the proposed decision system and the scores given by neurologists  do not eIn this paper, we introduced a new methodology that enables objective evaluation and quantification of the finger-tapping test that is usually used for bradykinesia assessment in patients with Parkinson’s disease. The system comprises two miniature and lightweight gyro sensors that record the motion of fingers. The methodology for signal quantification is based on the use of simple, automatized, and repeatable signal-processing techniques. In this study, 15 s long finger-tapping sequences were recorded and analyzed. However, the methodology is applicable to other approaches as well . Patients with finger-tapping bradykinesia severity ranging from 0 to 4 were included in this study. Most of the studies in the literature include severity stages up to 3, indicating that patients with the highest severity cannot perform specified tasks at all. In this study, we included three patients that barely managed to perform the finger-tapping task with one of their hands. However, their performance was poor and affected by multiple performance disturbances. Therefore, they were evaluated with the highest bradykinesia severity score (4). In this way, the performance of the proposed system was examined for the entire range of severity stages.The parametric result comprises features that can be directly correlated with biomechanical properties of the movement and can, therefore, be used to assist physicians during the assessment of bradykinesia in repetitive finger-tapping. For such a purpose, we implemented the time-frequency method continuous wavelet transform, which allows us to evaluate temporal changes in the tapping frequency and to detect irregularities in rhythmic tapping behaviour, such as hesitation and freezes. Numerical integration and drift removal were used for estimation of tapping angle apertures that are calculated for each tap. Temporal changes in the angle apertures were found and described by the index of the first tap with a significant amplitude decrement (compared to previously achieved tapping angle amplitudes). The final feature set is used as the input into the decision support system.Although the literature suggests that machine learning algorithms can predict scores with a high degree of accuracy, labels used for learning are given by physicians, which may cause subjectivity in the obtained results. Typically, only a few dozen recordings are used for learning, which is not a sufficient number of training examples to obtain a clinically acceptable system. Therefore, the decision support system consists of simple rules with decision boundaries designed to match the UPDRS scoring criteria. The decision boundaries for the tapping frequency and angle amplitude are defined according to the feature values obtained from the healthy controls and testing group of patients using the clustering techniques. As shown in The results of the decision support system  demonstrAs shown in the confusion matrices in The proposed system provides a complete analysis of repetitive finger-tapping performance, objective measures of important biomechanical properties of the movement, and a graphical presentation of the recorded data with specific changes and irregularities marked in the data. The system can differentiate between different types of performances and provides decision support through automatically calculated scores and subscores for different criteria for the evaluation of movements. The scores are given using rules that are specifically designed to match the universal clinical criteria for evaluation of bradykinesia severity in repetitive finger-tapping movements. In addition, the system was tested on patients with different forms of parkinsonism and at different disease stages, and for the full range of symptom severity . The proposed expert system is detailed and objective, and, therefore, it can be used as a powerful support tool in clinical practice for the evaluation of symptom severity, monitoring the disease’s progress and a patient’s response to therapy, and comparisons with other patients. In the future, an intuitive graphical interface for a software application will be developed to provide a graphical presentation, numerical results for features, scores and subscores, and a statistical analysis.Future work will also include collaborations with other researchers and groups to obtain larger databases and augment the data for analysis in terms of included subjects and the number of tests used to assess bradykinesia and other motor symptoms. We also plan to develop a metric to be used for more efficient differential diagnostics of typical and atypical parkinsonism.


The presence of motion artefacts in ECG signals can cause misleading interpretation of cardiovascular status. Recently, reducing the motion artefact from ECG signal has gained the interest of many researchers. Due to the overlapping nature of the motion artefact with the ECG signal, it is difficult to reduce motion artefact without distorting the original ECG signal. However, the application of an adaptive noise canceler has shown that it is effective in reducing motion artefacts if the appropriate noise reference that is correlated with the noise in the ECG signal is available. Unfortunately, the noise reference is not always correlated with motion artefact. Consequently, filtering with such a noise reference may lead to contaminating the ECG signal. In this paper, a two-stage filtering motion artefact reduction algorithm is proposed. In the algorithm, two methods are proposed, each of which works in one stage. The weighted adaptive noise filtering method (WAF) is proposed for the first stage. The acceleration derivative is used as motion artefact reference and the Pearson correlation coefficient between acceleration and ECG signal is used as a weighting factor. In the second stage, a recursive Hampel filter-based estimation method (RHFBE) is proposed for estimating the ECG signal segments, based on the spatial correlation of the ECG segment component that is obtained from successive ECG signals. Real-World dataset is used to evaluate the effectiveness of the proposed methods compared to the conventional adaptive filter. The results show a promising enhancement in terms of reducing motion artefacts from the ECG signals recorded by a cost-effective single lead ECG sensor during several activities of different subjects. An electrocardiogram (ECG) is a technique for diagnosis of cardiovascular diseases , and theMotion artefact is reported as the most difficult kind of noise to eliminate from ECG signals. The reason for this is that the spectrum of the motion artefact completely overlaps that of the ECG signal. In addition, its morphology resembles that of the P, QRS, and T waves . TherefoA motion artefact is a result of the change in the impedance between the skin and the electrode, which causes a transient change in the baseline signal . The chaReducing motion artefacts has been the subject of several studies, in the context of Digital Signal Processing (DSP) such as Discrete Wavelet Transform (DWT) –14, AdapIn this paper, a two-stage filtering algorithm is proposed. In the first stage of the proposed algorithm, a weighted adaptive noise cancelling method (WAF) is proposed. The acceleration of the electrode is used as noise reference, while the correlation between the acceleration and the recorded ECG is used as an updating weight factor. The acceleration signals were recorded using triaxial accelerometer integrated with the ECG electrode. The noise reference intensity is modified accordingly to the correlation with the acceleration. Thus, the impact of the adaptive noise cancelling algorithm on the ECG signal is decreased during low correlation conditions. In the second stage, a statistical -based filter is used for estimating the potential ECG signal. The recursive Hampel filter-based estimation method (RHFBE) is proposed for estimating the ECG structure. The Hampel filter  is used The main contributions in this research are summarized as follow.A two-stage motion artefact filtering algorithm is proposed to address the issue of adaptive noise filter due to the occasional and variable correlation between acceleration and ECG signal. A new filtering concept has been introduced which is the one-lead based spatial correlation between the successive ECG cycles (P-QRS-T segments). While the successive ECG cycles have similar characteristics, the motion artefact is random in the successive cardiovascular cycle. Therefore, the spatial correlation between the successive P-QRS-T segments has been exploited to remove the motion artefact.A Weighted Adaptive noise Filtering method (WAF) is proposed to address the impact of the occasional and low correlation between the ECG and the acceleration signal on the filtered ECG signal. The effectiveness of the proposed method over the conventional adaptive filter method has been shown.A R-peak Annotation and Signal Segmentation method (RAS) is proposed that use effective QRS detection algorithms to detect and annotate the R-peak. It worth mentioning that the use of the adaptive filter prior to the proposed segmentation method improves the QRS detection accuracy . MoreoveA novel spatial filter is proposed namely the recursive Hampel filter-based estimation method (RHFBE) which assumes that the motion artefact in the new P-QRS-T segment is far from the median of the successive P-QRS-T segments. Hampel filter is a robust statistical filter for removing outliers thus it is considered effective and efficient for real-time applications . The difThe rest of the paper is organized as follows. In section two, the related work is discussed. In Section three, the preliminary information that needed for the design of the proposed algorithm is briefly described. The proposed algorithm is explained in Section four. The performance evaluation and results are discussed in Section five and six, respectively. The conclusions are drawn in Section seven.Traditional digital signal processing filters such as band-pass filter, and Discrete Wavelet Transform (DWT) –14 are uIn the field of adaptive noise cancelling,  proposedTong et al.,  proposedYoon et al., in  used theLiu in  proposedZhang et al., in  investigLee et al, in  used empKirst et al, in  proposedIt is common practice to measure the electrode-skin impedance prior to ECG recording . HoweverHughes and John in  investigExisting motion artefact solutions either cannot totally remove the motion artefact or they lead to significantly changing the ECG morphology. The application of adaptive noise filtering is the most reported solution for motion artefact reduction. However, an adaptive filter needs a reference signal that is highly correlated with the noise in the ECG signal and not with the ECG information. If the correlation is weak, the resultant filtering signal can be wrong. Both ECG and motion artefacts are difficult to obtain in reality and they have also time-variant characteristics; therefore they are not easy to estimate in practice. However, the advantage of using adaptive filters is that the reference signal is not necessary. The motion artefact filtered signal is only suitable for detecting the QRS complex or arrhythmia. ANC cannot totally remove the noise, as it is difficult to find a highly correlated noise reference. In contrast, the presence of uncorrelated noise in the reference signal degrades the performance of the ANC.In this paper, a two-stage filtering algorithm is proposed for reducing motion artefacts from ECG signals recorded during normal subject activities. In each stage, a different filtering method is proposed. The first stage is to use the concept of an adaptive noise filter with acceleration as a reference and propose weighted adaptive noise filtering. The difference between this method and the existing adaptive noise filters is that the cross-correlation coefficient between the ECG and acceleration is used for modifying the adaptive filter weights. The noise is multiplied by a factor which is the cross-correlation coefficient between the raw ECG signal and the estimated noise signal through Least Mean Square (LMS) algorithm. Thus, the impact of the false reference signal is reduced, which lead to better resamples of the motion artefact. In the second filtering stage, a recursive Hampel filter-based estimation method (RHFBE) is proposed to further reduce the remaining motion artefact from the ECG signal which has low correlation with the acceleration signal. The Hampel filter is proposed for three main reasons. Firstly, the morphology of the ECG signals changes slowly with time, such that the successive ECG cycles have similar characteristics. Secondly, the motion artefact has a random impact on the ECG signal elements, i.e. the motion artefact is not repetitive in each cardiovascular cycle; therefore, the contaminated portion can be shown as an outlier with respect to the successive segments. Thirdly, the Hampel filter is a statistical filter outlier that is robust and thus it is considered efficient and effective for real-time applications. The Hampel filter is found to be fit for such a situation. Both the adaptive noise canceler and the Hampel filter are efficient and can work in real time.In this section, the preliminary information is presented in order to drive the proposed motion artefact reducing algorithm.The adaptive filter (AF) or the adaptive noise canceller (ANC)  is a filsecg+ma = secg+nma) that is contaminated by the motion artefact while the reference is the noise signal (nr). The output of the adaptive filter is the estimated noise As shown in By taking the mean of the square error of the equation above,secg and noise Because the signal nma can be resampled by Wk = [wk)123], where Wk is a vector which contains the filter’s coefficients at the time epoch k. The LMS algorithm can be written as follows:xr(k) is the reference noise and Xr(k) = , εk is the filtered clean signal and μ is the learning parameter, which can be calculated according to the following equation,β is normalized step size (0<β<2), and c is a small positive constant that prevents μk from taking large value when xr(k) is near zero. The estimated noise, Wk) is the reference noise.To minimize the mean square error, the least mean square (LMS) algorithm can be used. The LMS tries to adaptively adjust the filter coefficient so that The Hampel identifier is regarded as one of the most robust and efficient outlier identifiers . The HamXk =  with sliding window l at time epoch k, the median and MAD can be calculated as followsGiven a sequence After replacing the mean and the standard deviation by the median and MAD, the modified rule is written as follows:xk+1 is an outlier and replaces it with the median ∅k if it is located away from the mσth times the standard deviation.The HF identifier declares that The QRS complexes in an electrocardiogram represent the depolarization phenomenon of the ventricles and yield useful information about their behaviour. Detecting the QRS complex is a very common procedure for analyzing ECG signals in healthcare systems. It is the first step in the automatic ECG processing algorithms. Real-time QRS complex detection is essential for monitoring of patients in critical heart condition. Therefore, many researchers in the QRS-Complex detection have focused on increasing the performance in terms of detection accuracy and computational complexity of the detection. The scope of this study is limited at utilizing one of the existing real-time QRS detection algorithms to label the R-peak locations in the ECG signal in order to accomplish accurate segmentation of the QRS complexes.QRS complex detection is considered simple task and can be done efficiently for clinical ECG recording. Many effective techniques have been proposed for QRS detection algorithms, including using neural networks , the hidThe aim of this section is to explain the proposed algorithm. The main goal of the algorithm is to reduce the motion artefact of an ECG signal acquired through portable or mobile ECG while a subject performs normal activities. The proposed algorithm consists of five modules, as shown in The pre-processing phase consists of two parts, the Butterworth band-pass filter for removing high frequencies followed by notch filter for eliminating the 50/60Hz power line interference, and the adaptive noise canceller for removing baseline wandering. Industrial environment can be a source of radiation generated by high voltage power lines, transformers, welders, electric motors, induction furnaces, degaussing coils, etc. Thus, in the first part, the ECG signals are digitally filtered with a zero-phase Butterworth IIR bandpass filter (0.05–130 Hz). The notch filter is used as stopband to suppress the 50/60Hz power line interference.The second part uses the adaptive baseline wandering reduction filter (ABWRF) proposed by . The conThe goal of the adaptive filter is to adapt the filter coefficient in order to estimate the motion artefact in the ECG signal. This filter is designed based on a conventional noise canceller (ANC) namely the adaptive filter (AF). The AF is modified to include the correlation between the noise reference and the ECG signal as a weight for adjusting the amount of filtering according to the correlation. Thus, the impact of the uncorrelated noise is reduced and a better ECG signal is obtained.nr) and the ECG signal (secg_ma) ρk)( = [ρk)123] is multiplied by the weights to reduce the impact of uncorrelated noise from disturbing the original signal, as follows:To prevent formation of incorrect nr is the noise reference and ACCSVM is the SVM value of the recorded accelerations in the three axes, x, y and z, respectively.A triaxial accelerometer is attached to the ECG electrode and used as noise reference, namely the component of the triaxial record vector is compounded to on value so-called Signal Vector Magnitude (SVM). Similar to many previous research such as in , 37, thek, the QRS detection algorithm is then used to annotate the buffered signal. An indexing vector is created to mark the location of the QRS complex, namely the R spike, by setting the location to one. A window started at the R peak signal is then used for signal segmentation. The R-peak is selected in the beginning of the window inorder to address the issue of the irregulare heartbeat signal (Arrhythmia). A complete segment containing the P-QRS-T signal with fixed length is separated and stored in the matrix which contains L time-sequences as follows:k is the time epoch of complete P-QRS-T signal, which is the moment when the R peak occurred, w is the number of signals that were taken into account from successive ECG signals, and l is the length of the complete P-QRS-T ECG signal . w is set according to the amount of time that the signal is stationary. With the assumption of an uncorrelated noise signal, w may be selected according to the interquartile range IQR length of each column in the Bufferk. IQR is a measure of variability which is the difference between the first and the third quartile of each column in the Bufferk. If all IQRs are small, this is an indication of a precise signal, so a small buffer size (w) is enough to estimate the correct ECG signal. Meanwhile, if the IQRs are large, then this is an indication of imprecise ECG signals; thus a larger buffer size, w, should be used. If a corresponding change occurs in RR length, then, with large IQR, this indicates that a motion artefact is present in the signal.The output of the WAF algorithm is buffered. For each time epoch w should be updated online, accordingly. The use of relative entropy, also called the Kullback−Leibler divergence, is suggested to compare the probability density function of two windows that are taken from the filtered ECG signal. If the relative entropy is zero or near zero, then buffer size should not be decreased until the initial buffer size. Otherwise it should be in,creased until the entropy becomes a small value, as illustrated in p(x) and q(x) are two probability distributions of a discrete random variable x. The relative entropy with respect to q can be obtained as follows:To capture the change in the ECG signal, the buffer size l is estimated from the information stored in the Bufferk as follows. Since the minimum duration of a single P-QRS-T signal is around 0.14 seconds when the heartbeats rate reaches 300 per minute and the maximum duration of a single P-QRS-T around 1.2 seconds when heartbeat rate falls to 50 per minute [l is 0.14 and the minimum value is 1.2. Meanwhile, l is estimated by subtracting two successive QRS peaks. Although the buffer width l is adjusted automatically in this paper, the maximum and minimum values are used as a cutoff threshold to avoid taking a wrong P-QRS-T length. This values can be adjusted manually by the physician or the user based on information obtained through medical examination. For example, athletes may have heartbeat rate around 38, thus, the maximum value should be adjusted to be 1.58 seconds. In case of undetected QRS complex, the l takes the pervious value. The algorithm in The duration of the signal can vary according to the heartbeat rate information. In this paper, r minute , the maxk, the median absolute deviation (MAD) δk, Hampel filter upper bound HUBk, and Hampel filter lower bound HLBk. The Hampel filter’s parameters are calculated as follows.k is the time epoch of the complete ECG signal and i is one sample of the ECG segment, w the buffer size (in terms of number of the ECGs segments in the buffer), and l is the length of the ECG segment.The idea behind suggesting Hampel filter for removing motion artefacts in the ECG is that the successive ECG segments have a repetitive structure while the motion artefact is random in each segment. Thus, the Hampel filter can recover the original ECG structure from a noise contaminated one. The Hampel filter needs four important parameters to perform the estimation: the median ∅The filter response is given by:Therefore, the estimated signal will be as follows:The input of the Hampel filter can be written as vector containing the complete ECG signal (P-QRS-T) that represents a cardiac cycle of the ECG signal as follows:https://archive.ics.uci.edu/ml/datasets/MHEALTH+Dataset” which was last retrieved on 5-June 2018.The effectiveness of the proposed algorithms was evaluated in the Matlab environment. The Mobile HEALTH (MHEALTH) dataset , 49 wereAs the MHEALTH dataset contains different activities, the reference P-QRS-T segment can be used for the evaluation which can be obtained when subject’s activity is low, such as standing still, sitting and relaxing, and lying down. However, due to the non-stationary nature of the ECG signal recorded during relaxing, this cannot be used to evaluate the ECG signal during running or jogging. Therefore, a ground truth ECG reference signal is unavailable for the evaluation. In addition, the absence of a ground truth motion artefact noise reference makes it difficult to evaluate the effectiveness using signal to noise ratio (SNR). In addition, QRS complex detection is not a reasonable measure for evaluating motion artefact reduction methods because of the presence of highly accurate QRS detection methods that can accurately detect the QRS complex even if there is a motion artefact or poor ECG signals are used. Therefore, in order to evaluate the effectiveness of the proposed method, the morphological change in the ECG is recorded and evaluated.In this section, the results of the proposed filtering algorithms are presented and organized in three subsections as follows. In the first subsection, analysis of the correlation between the ECG and the acceleration signal is conducted. Then, the proposed weighted adaptive filtering method (WAF) is evaluated and compared to the conventional adaptive filter (AF) method. Finally, the Hampel based filtering algorithms (HFBE and the Recursive Hampel filter RHFBE) are evaluated and compared to the AF and WAF algorithms.In this section, the correlation between the motion artefact contaminated ECG signal and the acceleration signal has been studied. To further study the correlation in more details, In this section, the effectiveness of the adaptive filtering methods is studied. The results obtained by applying the proposed weighted adaptive filter to different ECG signal recorded while the subject performing different activities are discussed and compared to the conventional adaptive filter. Figs To quantitatively evaluate the performance of the adaptive filter algorithms regarding the motion artefact reduction, the power ratio (PR) is used as an indication for the improvement of the quality of the motion artifact contaminated ECG signals , 51. PR E(|Psecg|2) represents the power value of the raw ECG signal before the filter, E(|Pdecg|2) is the power value of the desired signal (after filteration). In adaptive filter, the error signal is the desired information i.e. the filtered ECG signal. Where In contrast to as the studies presented in , 19, 40 In this section, the effectiveness of Hampel-based filtering is evaluated. The performance of the both HFBE and RHFBE are studied and compared. x-axis represents the time epochs while the y-axis represents the ECG potential intensity. The solid line represents the ECG signal after applying the Hampel based filter. Meanwhile, the dotted line represents the removed motion artefact signal which is the difference between the signal before and after filtering . The highlighted region in the In To simplify the explanation, four regions in The performance of the proposed filtering methods was evaluated using QRS complex detection algorithms namely the Pan and Tompkins algorithm. Pan and Tompkins algorithm was proved to be the more effective compared with the state of the art R-peak detection algorithms . The QRSAs illustrated in Moreover, the performance of the proposed algorithms is further evaluated in terms of heartbeat rate estimation. Meanwhile, the heartbeat rate estimation error (HBRE) is computed by subtracting the actual human-based estimation from the estimated heartbeat rate, As shown in In conclusion, statistically-based filtering such as the Hampel filter shows its advantage in filtering ECG signals contaminated by motion artefact type noises. This method can be used for filtering many signals that have repetitive structures, such as respiratory signals. The advantage of the proposed Hampel filter-based method is that it is real-time realizable because it is based on a statistical approach. The potential issue with the proposed method is that if the QRS complex is totally contaminated, then the motion artefact in that particular ECG segment will not be recovered. To remedy this issue, the occurrence of the ECG segment e.g. the R-peak should be predicted by analyzing the the signal structure of the subsequent cardiac cycles. This is a trivial task, due to the availability of knowledge about the maximum and minimum length of two successive R-peaks . The task also is easier in the sinus rhythm signals rather than arrhythmia signal structures.mth number of the median absolute deviation as illustrated in Eq Click here for additional data file.S2 Supporting Information(RAR)Click here for additional data file.


This paper describes the concept, the technical implementation and the practical application of a miniaturized sensor system integrated into an autonomous underwater vehicle (AUV) for real-time acquisition of water quality parameters. The main application field of the presented system is the analysis of the discharge of nitrates into Norwegian fjords near aqua farms. The presented system was developed within the research project SALMON  over a three-year period. The development of the sensor system for water quality parameters represented a significant challenge for the research group, as it was to be integrated in the payload unit of the autonomous underwater vehicle in compliance with the underwater environmental conditions. The German company -4H- JENA engineering GmbH (4HJE), with experience in optical in situ-detection of nutrients, designed and built the measurement system. As a carrier platform, the remotely operated vehicle (ROV) “CWolf” from Fraunhofer-Institut für Optronik, Systemtechnik und Bildauswertung - Institutsteil Angewandte Systemtechnik (IOSB-AST) modified to an AUV was deployed. The concept presented illustrates how the measurement system can be integrated easily into the vehicle with a minimum of hard- and software technical interfaces. Aquaculture production increased from 5 million to 63 million tons during the last three decades, while capture fisheries production increased from 69 million to 93 million tons in the same time period . StudiesThe Marine Directive of the European Union is aimed at good environmental status (GES) of the EU’s marine waters by 2020 . A sustaThis paper describes an approach to improve the observational methodology of the environmental impacts by developing an automatic, unmanned underwater measuring device for sampling the water column properties. The device measures the standard physical water body properties such as temperature and salinity. Additionally, the system allows for observing other parameters such as oxygen, chlorophyll and nutrients, which are all crucial for the welfare of the naturally living resources near aquaculture sites.Nowadays, there are many systems for monitoring fish farms. An overview about relevant works for tanks and ponds is presented in . In thisAll presented systems above allow long-term and stationary monitoring of fish behavior and water parameters. The main issue of these systems is the spatially limited measurement in a fixed depth, where only a few measurement locations can be observed. Moreover, the equipment can stay a long time under water and can provide online data. In combination with a spatially distributed measurement approach using an underwater vehicle like an ROV or an AUV, it is feasible to combine the data and augment the stationary measured values with the vehicle measurements. Furthermore, the long-term deployment of sensors needs to consider the topic of biofouling and maritime growth that can influence the measurements. Some sensors need regular cleaning, where a short-term deployable platform such as an underwater vehicle is a good alternative.Although several ROV applications in fish farms have been published in the past few years, the use of AUVs to solve possible tasks in and around fish farms is scarce. ROVs are in many cases a cost-effective alternative and less dangerous than using divers. In , an accuThis paper includes a summary of the main results of the research project SALMON and has been previously published partly in ,12,13. TAs a carrier platform for mounting the sensor system, the Hybrid Autonomous Underwater Vehicle CWolf from the Fraunhofer IOSB-AST was used. The vehicle can operate fully autonomously or tethered with a fiber optic connection. Its modular payload concept allows for an easy sensor integration. The CWolf hardware is based on the pressure vessel construction of the widely mission tested Seawolf ROV produced by ATLAS ELEKTRONIK, Bremen, Germany.The pressure vessel construction is segmented as shown in The CWolf is equipped with four stern propellers for movement and maneuvering the vehicle. Different control commands of the horizontal or vertical propeller pairs result in a yaw and pitch torque. This allows the rotation of the vehicle without rudder units. Two additional vertical thrusters at the bow and stern are used for hovering and for pitch control during low speed operation. Due to the modular concept, additional horizontal thrusters can be added so that the vehicle can move sideways. This concept also allows for an easy integration of the application task with a minimum of hard- and software technical interfaces. Different kinds of payloads can be integrated into the pressure hull segment. For different payloads, different hull segments can exist and this makes the payload exchange very simple. A flange mechanically connects the segments and a bus system provides standard power supply and communication interfaces such as Ethernet, RS232 and Controller Area Network (CAN). The vehicle base platform provides accurate navigation data for vehicle guidance and geo-referencing the measured values. It consists of an inertial navigation system (INS) using several technologies such as a fiber optic gyro, a Doppler-velocity log, Global Positioning System (GPS), pressure sensors and USBL localization. The most important technical data of the AUV is shown in The company -4H- JENA engineering GmbH (4HJE)   developeThe developed sensor system is integrated in a cylindrical hull segment matched with the diameter of the entire submerged body. Ring-shaped adapters in combination with sealing rings allow a pressure-tight connection to the rest of the submerged body. The off-the-shelf sensors used allow easy maintenance and changing from the outside without removing the segment. In addition, the inlet and outlet filters are changeable during field operations. The water analysis process follows the following path: Inlet Filter → Micro Annular Gear Pump → Cuvette Unit → Temperature Measurement → Outlet with Check Valve and Filter. The Scientific Computer (SC) and the Measurement Computer (MC) are situated in the lower part of the segment. These computers were connected with the internal vehicle communication unit via Ethernet. Since the nitrate measurement water had to be pumped through the vehicle, a leak sensor was installed at the bottom of the hull segment.For the determination of nitrate, an optical method is used. The medium to be measured is pumped through a measuring cuvette via a hose system. A deuterium lamp emits ultraviolet radiation at the medium in the cuvette see . Some waThe integrated spectrometer detects the intensity of the different wavelengths. Using stored spectra of purified water or seawater with known nitrate concentrations, the current nitrate concentration can be calculated by the MC. Additional factors influencing the measurement are the temperature of the measured medium, as well as other components in seawater. These are considered in the calculations.To adjust the measuring range of the system, the length of the cuvette must be selected accordingly. In a longer cuvette, more light is absorbed even when the nitrate concentration is low, thus the sensitivity increases with the length of the cuvette. If the cuvette is too long, too much light is absorbed and the spectrometer receives too little values for the calculation. The cuvette, which is used in the mobile analyzing unit has a length of 1 cm and is shown in ConSys [The modular control software ConSys  is respoThe algorithms for navigation, control and monitoring the electrical components  run on the Control Computer (CC), which is located on the vehicle base platform. It provides an interface to receive navigation data, the vehicle status and error messages and controls several actuators in the Low Level Controller (LLC). The vehicle guidance runs as a backseat driver on a Scientific Computer (SC), which is located in the payload unit. A Measurement Computer (MC) for the water quality measuring management is also located there. For communication between the applications on the computers, the User Data Protocol (UDP) is used. This ensures operating system and compiler independency of the interacting software programs. LLC_Command is needed to activate the vehicle control from the SC. Therefore, it can be switched to a controlled mode, a direct mode or off mode, when the SC finishes the vehicle control. In controlled mode, the LLC requires a heading, depth and speed command. In the SALMON project, direct mode was used whereby the SC controls the vehicle propulsion engines directly. It has to send a LLC_Setpoints_CWolf telegram, which includes the Pulse-width modulation (PWM)-values for each single motor.The telegram NAV_Data telegram includes the actual vehicle location , the vehicle orientation, speed, and height over ground values. The LLC of the CC communicates between the motor hardware and the CC-software. It receives the LLC_Setpoint_CWolf and LLC_Setpoint telegrams and sends LLC_Status, containing the current motor status, and LLC_Error telegrams, when an error has occurred. The unique identification of telegrams occurs with a header at the beginning of a telegram, which contains a message Identification (ID) and the message-payload length.The CC distributes the actual navigation data every 100 ms to all software modules. This is more than what is used by the SC and MC to handle the mission, to control the vehicle and to record the water quality measurements. The (1)Defining the sea chart/area of interest,(2)Selection of the vehicle, and(3)Build a plan using defined mission elements.To create a mission plan, a menu-guided planning system was used. This system evolved from the planning system developed in the EU project GREX  and consThe dive profiles are yo-yo style and arranged in a meander to cover the whole area. The mission element meander is specified by the following parameters: start position To detect the water quality parameters in several depths, two dive profiles were preferred. The first has a saw tooth shape see a similar(i)to test the autonomous guidance of the vehicle and the sensor system in practice, and(ii)to monitor the water quality around the fish farms.The field trials of the prototype were carried out in the second half of October 2013. The operation area is located about 30 km south of Bergen, Norway on the island of Austevoll near the experimental fish farms of the Institute of Marine Research . The goaTo receive the current vehicle position and its status as well as the measurement data online, the vehicle was tethered via a fiber-optic cable also during the autonomous missions. This allowed the manual control of the vehicle in case of an emergency, like an inrush of water or a collision situation with a passing ship.The first trial focus included the validation and adaption of the vehicle model and the controller design on the used vehicle structure as well as the tests of the guidance algorithms on the vehicle and the developed mission planning system. During the individual dives, the sensor system was active and logged water quality data. These trials occurred in a sheltered bay without shipping traffic. The access to the water occurred by a ramp using the transport trolley.The final trials were conducted between the two fish farms see . To launFor the mission, a meander-shaped plan consisting of 45 waypoints was defined. The farm locations were also considered in the mission planning as ‘no go area’. This allows for keeping a safe distance to the fish farms to avoid possible interactions between the AUV and the farms. The AUV headed for the individual waypoints , theresponse . The parThe data profiles of the two dives are shown in y< 1.3 s ) is negly< 1.3 s  providesom CSIRO  was useden< 25 s ) is alsoThe generated depth profiles using the mean of the data values after the settling process in the individual depths , the launching process using the ramp or the crane was very challenging. Three employees were required for this. Here, a decrease of the vehicle-payload mass relation is desirable, which is currently 8.3 to 1. Man-portable AUVs like a REMUS 100  , an LAUVThe communication via fiber optic cable, which was used during the trials, will not be used in future real operations. Two configurations are possible: (a) an acoustic link will provide low bandwidth communication for telemetry, online measurement data transfer and emergency situations; (b) a collision avoidance system will work on board, which is described in . This syFor future use, a simplification of the sensor system is necessary. This includes an automatic initialization process and a transparent depiction of the data. It is also conceivable to relocate the water-bearing sensor parts of the nitrate measurement outside of the hull segment. This leads to a smaller and more robust system as well as to an increase in operational safety because no sample water needs to be pumped into the vehicle. In addition, the correct incident flow of the sensors with sample water in hover mode has to be analyzed in detail. The time delay of the standard sensors was noticeable. In case of a mission consisting of saw tooth profiles, an additional correction algorithm or a sensor unit which has smaller response times installed in gliders  have to The gained experience and the discussions with the employees of the fish farm show that an AUV is not the ultimate solution for fish farms. They need an easy-to-use system with a short lead and follow-up time. Based on these considerations, a modular sensor system will be favored see . This syIn this paper, we present the concept, the technical implementation and the practical application of a miniaturized sensor system integrated into an autonomous underwater vehicle (AUV) for real time acquisition of water quality parameters around fish farms. We demonstrated the possibilities and the restrictions of using autonomous underwater vehicles for water quality analysis for aquaculture and coastal areas. Interested readers will find detailed information about the operating principle of the sensor system and the AUV. Furthermore, we discussed how important an intuitive and efficient handling of a modular sensor system is for future users.


Complicated crown-root fractures of primary teeth often present with a greater challenge to the pediatric dentist. Extraction of the involved tooth is the routine treatment indicated. But, early loss of this primary tooth may lead to esthetic and psychological problems and also causes a detrimental effect on the development of occlusion and the alveolar bone. The present case report described the management of crown-root fracture in a primary canine by surgical extrusion and showed a satisfactory prognosis at one-year follow-up. Trauma to the teeth and orofacial region is most commonly encountered in children compared to adults. The child age and behaviour management play an important role in deciding the treatment protocol. The fracture line originates in the crown portion of the tooth, extends apically into the root in an oblique direction, and frequently exposes the pulp which is termed as a complicated crown fracture. The management protocol should consider both the function and the esthetics of the fractured tooth . VariousSurgical tooth extrusion is considered to be one of the most favourable treatment options when the fracture line extends subgingivally. The procedure involves severing the bone root periodontal attachment utilising a surgical instrument to place the root in a more coronal position –4. The eThe present article describes a case of management of crown-root fracture in a primary canine by surgical extrusion, when followed up for 12-month duration that showed a satisfactory prognosis.A 6-year-old girl presented to the Department of Pediatric and Preventive Dentistry with the history of trauma in her right upper front region of the jaw. She had a fall on the school ground while playing 1 hr before the presentation, had no symptoms of nausea, and did not have any discharge or bleeding from her nose. The medical history was unremarkable and did not have any history of daily medication. No gross facial asymmetry was evident. She had no abrasions on the lower or upper lip. Her temporomandibular joints were functioning within limits and with no clicking, pain, or any abnormal mandibular deviation. On intraoral examination, the patient had a complete set of primary dentition and had moderate oral hygiene, with mild plaque deposits at the gingival margins. There was a fracture in the right maxillary canine (tooth number 53) with the oblique fracture line extending subgingivally . RadiogrThe treatment options and prognosis for tooth 53 were discussed with the patient's mother. Preoperative photographs were taken, and local anaesthesia was administered  on the buccal and palatal aspects of tooth 53. The mobile tooth fragment was extracted, and the remaining tooth structure was surgically extruded using a maxillary anterior forceps . OcclusiCrown-root fracture typically presents as a fracture line that originates in the crown portion of the tooth which extends apically in an oblique direction frequently with pulp exposure. The treatment protocol for primary teeth with crown-root fracture as recommended by IADT guidelines is to leave the tooth untreated if the coronal fragment is not displaced or extracting the coronal segment with repositioning and splinting might be considered [nsidered . In sevensidered , 7.The surgical extrusion is considered a viable alternative for the management of crown-root fracture, when the fractures extend subgingivally and periodontal surgery is not recommended owing to esthetic reason. When compared with orthodontic extrusion, which involves placing either post or brackets in the exposed tooth surface, this treatment option allows the detection of additional fractures at the root. Moreover, studies show that surgical extrusion has an acceptable prognosis; approximately 80% of teeth treated are still in working condition after five years , 4. It iIn the present case report, the traumatised teeth were surgically extruded followed by the extraction of mobile tooth fragment in the coronal portion, splinted and stabilised. In the next appointment, the teeth were treated with pulpectomy and coronal restoration. On eight-week follow-up, the tooth exhibited no clinical signs of failure, such as mobility, tenderness, or pain. The outcome was successful in this case at one year, as there was no underlying pathology in the follow-up period suggesting no risk for the underlying permanent tooth germ. The long-term success of surgical extrusion depends on the cooperation of the child, the condition of the periodontal ligament, the vitality of the teeth, and the time lapsed following trauma. Thus, the conservative approach in the management of crown-root fracture in primary dentition should be emphasised. Further more studies of similar case reports are desirable in the management of crown-root fractures in primary dentition, before any recommendations to be made in the guidelines of the management of trauma.In conclusion, this case report confirms that a multidisciplinary approach surgical extrusion is one of the alternative methods to manage the complicated crown-root fracture in a primary dentition.


Almost inevitable climate change and increasing pollution levels around the world are the most significant drivers for the environmental monitoring evolution. Recent activities in the field of wireless sensor networks have made tremendous progress concerning conventional centralized sensor networks known for decades. However, most systems developed today still face challenges while estimating the trade-off between their flexibility and security. In this work, we provide an overview of the environmental monitoring strategies and applications. We conclude that wireless sensor networks of tomorrow would mostly have a distributed nature. Furthermore, we present the results of the developed secure distributed monitoring framework from both hardware and software perspectives. The developed mechanisms provide an ability for sensors to communicate in both infrastructure and mesh modes. The system allows each sensor node to act as a relay, which increases the system failure resistance and improves the scalability. Moreover, we employ an authentication mechanism to ensure the transparent migration of the nodes between different network segments while maintaining a high level of system security. Finally, we report on the real-life deployment results. To date, the development of various industries has brought a tremendous impact on our climate. According to the National Aeronautics and Space Administration (NASA), global climate change already has effects that can be observed in the environment. Glaciers have shrunk, ice on rivers and lakes is melting ahead of time, plant and animal habitats have changed, and trees bloom ahead of expected dates . The preAccording to the European Commission, the main impact on climate change is due to the greenhouse effect, which is mainly caused by COman-made ). Its coOne of the critical aspects in reducing the negative impact on the climate is efficient monitoring of the environmental data in addition to prompt actions aiming to reduce such impact in dedicated areas. Indeed, many researchers are actively improving and developing new solutions utilized for monitoring. After broad adoption of the Internet of Things (IoT), growing interest from industry, researchers, governments, and developers was given to IoT’s particular niche — Industrial IoT (IIoT) . This seIIoT provides a number of main machine-oriented development directions, including: (i) factory automation; (ii) mission-critical communications; and, generally, (iii) monitoring . HistoriIn this context, environmental and agricultural monitoring fields are ideal candidates for trialing and deploying the IIoT solutions . No doubThe industrial trends of today aim at “connecting the unconnected”. Presently developed systems sometimes fall behind the expectations due to their complexity and lack of proper community support. Thus, freely programmable and advanced Cyber-Physical Systems (CPS) should replace conventional programmable logic controllers in managing physical objects . SimultaCurrent research is also vital for the analysis of technological requirements and interconnections between different characteristics for distributed ledger technology (DLT) design. Developers need to conduct a comprehensive comparison between prospective DLT designs before starting the implementation suitability for a particular application . EnvironModern environmental monitoring applications and scenarios are reviewed.The pairwise key-based authentication mechanism was applied for urban environmental monitoring, allowing to handle individual system operational phases, e.g., the addition of new nodes, (un-)authorized migration of the node from one network segment to another, etc.An analytical framework based on Markov chain analysis that allows evaluating potential network topology changes is presented.A prototype of the proposed secure distrusted sensor network (operating based on the discussed authentication mechanism) was deployed in a real-life scenario.In this paper, we propose and develop the CPS system titled “Galouis”, which is a flexible environmental monitoring tool relying on the distributed network architecture. Dell-EMC carefully managed this work and supported the deployment in the metropolitan area. The main contributions of this work are:The paper is structured as follows. Focusing mainly on the Smart City paradigm from the IIoT perspective, the main activities of environmental monitoring could be listed as the following  see sel. The firA massive section of this group is related to industrial control , aiming The second big group is related to rural environmental monitoring : (i) lanIt is important to notice that the entire deployment predictivity of the IIoT sensor network is somewhat challenging due to a significant number of nodes involved. Moreover, devices could disconnect from the network, reconnect again, or move to another segment of the network without notifying the coordinator. The use of distributed sensor networks with flexible topology requires the utilization of secure yet straightforward authentication protocols.One of the most significant challenges of dynamic WSNs is the lack of centralized authority coordination. Such a center should provide storage, generation, and dissemination of the certificates to each sensor node operating within the public key infrastructure (PKI) paradigm . If the The developed system is a distributed self-organizing sensor network designed to monitor the parameters of the urban environment. It allows for the data transmission only from the trusted sensors that confirm their association with a specific network. The monitoring of the data is carried out remotely using a trusted Internet portal with a graphical user interface (GUI). A trusted addition and removal of the sensor are carried out using a smartphone application given the assumption that the device supports IEEE 802.11 protocol operation.The system was designed considering the requirements of urban environmental services, city administration, and emergency services. In addition, some information received and processed by the system can be provided to third parties for planning mass events, as well as to citizens to inform them about the environmental situation. In the case of providing information to citizens, data may be shown in quantitative form, e.g., in the form of geographical information systems (GIS).The developed system aims at solving the problem of promptly informing relevant services regarding possible emergency situations, allowing for better prediction and fast reaction.Simplex mode: The operation of the system is executed according to the “star” topology, and the transmission of messages to the Access Pontes (APs) directly using a controlled sleep mode.Duplex mode: The operation of the system is executed according the mesh network mode with relaying via the closest network nodes using a controlled sleep mode.Half-duplex mode: The operation the system is executed via the star topology but using a predefined sleep mode, i.e., the preset of the optimal mode for a given scenario and operating conditions are applied.The system is designed to operate in three different modes:Utilization of relaying strategy in duplex mode can significantly reduce the number of APs required for a deployable wireless network reducing the system’s overall deployment cost.The proposed system allows us to solve the task of environmental monitoring by constructing a self-organizing network of sensors using a secure protocol for direct data exchange between the nodes or through a third-party network. The obtained data can be aggregated and visualized at the dedicated server, indicating the geo-position of the device for collecting visualized data. Such online portal allows for quick response to critical changes in the selected parameters as well as in the data analysis for future prediction.The main challenges of urban environmental monitoring are the deployment simplicity and flexibility in terms of the mesh network reconfiguration  as well In this paper, we propose an advanced protocol for the initial authentication and addition of sensor nodes to an existing distributed network. During the operation of the system, a secure data transfer protocol is implemented based on pairwise authentication of the sensors in terms of their location, which protects the system from the unauthorized introduction of a malicious sensor or a critical change in the location of the legally installed sensor, and also prevents from false information updates. The system aims to enable flexible and efficient support for potential sensor network topology dynamics. The resulting general overview of the environmental situation will allow responding to critical changes in the monitored parameters quickly. Nonetheless, a flexible network configuration feature aims to cover the monitored territories in order to obtain the most accurate and useful data that can be further used for the analysis of the urban situation and planning measures to improve it.Today, there are many critical security issues in the data transmission and processing in the scope of dynamic sensor networks with variable topology . In partThis section is mainly focused on possible solutions for the sensor networks creation and providing support for secure mutual authentication of their sensors (nodes) that could be utilized for urban environmental monitoring.Gateway or Access Point (AP) is used for the end-node data aggregation. APs could also perform edge preprocessing of the incoming sensor data before the cloud delivery. Each data packet from each sensor node is encrypted using cloud public key to provide an additional level of the data integrity.Monitoring nodes are equipped with different sensing devices with the primary goal of collecting the specified environmental parameters, e.g., temperature, humidity, noise level, etc. The nodes could either connect directly to the AP or relay the data through the neighboring nodes to the AP in the ad hoc-like way.For our system, we assume that the network components are classified to only two groups, as shown in The main abbreviations used in this work are given in Sensor initialization (addition): For example, a phase when a new node should be connected to any available node or AP in range , we make a transition to the right on the Markov chain, but if the node has not failed  principle. Additionally, this platform improves the initialization process by the automated ntroller  equippedntroller . The priInitialization “duckling” of the devices  by usingAccess sharing;Routing between devices;Remote access; andSetting up the network credentials, and other tasks.The primary goal of the platform was to handle issues related to security, connectivity, and access management, while the developer only needs to design the device and customize the data processing. In particular, the platform is prepared to be transparent for developers to perform the following:To register in the cloud and generate its encryption key. In this case, the generated encryption key is stored only on the user smartphone but could be sent to the cloud.To perform node initialization.To interact with already initialized devices directly when they are in the communication range of the selected wireless technology.To specify access credentials of known APs and distribute those to all related devices.To interact with the devices via the infrastructure network. In this case, all transferred data are protected with end-to-end encryption between the smartphone and the node.The platform allows rapid development of the user application using Java library based on the following list of actions:When initialized, ESP8266 can be accessed by Universal Asynchronous Receiver/ Transmitter (UART) protocol, e.g., it could be used to securely send/receive arbitrary JSON-packed data to/from server or smartphone.According to the proposed platform and the above described protocols, we developed an urban monitoring system prototype based on ESP8266. Our nodes are currently equipped with the following sensors: COFor ease of use, we developed a custom monitoring data representation. The visualization side is a software module written in Hypertext Preprocessor (PHP) that generates a Hypertext Markup Language (HTML) views. Each view provides the user with an intuitive representation of the monitoring data received from the database after required Cloud processing. The information on the HTML page is updated via asynchronous requests. Measurements visualization, represented by the corresponding graphs, is carried out using the FlotJS library . A sensoThe system is composed of two modules responsible for: (i) data analysis; and (ii) CU. The CU allows to modify the operating mode of each node  remotely and provides the legal user with a mobile application for initializing sensors.The overview of the user Dashboard view is given in After the selection, the panel shows each sensor’s location along with the monitored environmental data visualized in the plot. The axes are scaled automatically according to the data received. The representation could be changed based on the control buttons located below the plot. For example, there is a possibility for scrolling the graph to overview previous results, selection of the displayed data range, and control of the measuring interval of the sensor in half-duplex mode. From the developed authentication methodology perspective, we tested all the cases listed in Climate change brings the problem of environmental monitoring to an entirely new level, especially for urban scenarios. In particular, the leading cause of indoor air pollution is inefficient fuel combustion from rudimentary technologies used for cooking, heating, and lighting in addition to complex traffic conditions in metropolitans. All of the above require practical and flexible enablers for monitoring the emission levels, temperature, and other factors affecting citizens’ lives.In this work, we first discussed a pairwise key-based authentication methodology followed by the prototype of the secure urban environmental monitoring system and the executed field trial. Despite conventional sensor network goals, the system allows protecting a sensor network from unauthorized topology changes, keeping the properties of scalability and security from a communications perspective. The platform was developed to enable efficient and fast network initialization, received information processing, and handling potential topology changes. The use of mutual authentication protocol, together with our platform, allowed us to build an efficient, safe, and easily scalable sensor network to collect and process environmental information. The expertise collected during this system prototyping would be further used for the DLT design principles formulation.Concluding, the developed system received positive feedback from the customer (DELL) and the research community during the IoT Summit Siberia, where the solution was presented to the broad public. The mayor of the city also provided his vision on how to further utilize the system for environmental and Smart City purposes. The developed system could also be efficiently utilized in farm and suburban scenarios where the connectivity to the gateway access point is relatively close to any segment of the mesh network.