Objective In this study we aimed to examine the reliability and validity of the wristband activity monitor against the accelerometer for children.Methods A total of 99 children(mean age = 13.0 ± 2.5 y) wore the t...Objective In this study we aimed to examine the reliability and validity of the wristband activity monitor against the accelerometer for children.Methods A total of 99 children(mean age = 13.0 ± 2.5 y) wore the two monitors in a free-living context for 7 days. Reliability was measured by intraclass correlation to evaluate consistency over time.Repeated-measures analyses of variance was used to detect differences across days. Spearman’s correlation coefficient(rho), median of absolute percentage error, and Bland-Altman analyses were performed to assess the validity of the wristband against the Acti Graph accelerometer. The optimal number of repeated measures for the wristband was calculated by using the Spearman-Brown prophecy formula.Results The wristband had high reliability for all variables, although physical activity data were different across 7 days. A strong correlation for steps(rho: 0.72, P < 0.001), and moderate correlations for time spent on total physical activity(rho: 0.63, P < 0.001) and physical activity energy expenditure(rho: 0.57, P < 0.001) were observed between the wristband and the accelerometer. For different intensities of physical activity, weak to moderate correlations were found(rho: 0.38 to 0.55, P < 0.001).Conclusion The wristband activity monitor seems to be reliable and valid for measurement of overall children’s physical activity, providing a feasible objective method of physical activity surveillance in children.展开更多
Obesity poses several challenges to healthcare and the well-being of individuals.It can be linked to several life-threatening diseases.Surgery is a viable option in some instances to reduce obesity-related risks and e...Obesity poses several challenges to healthcare and the well-being of individuals.It can be linked to several life-threatening diseases.Surgery is a viable option in some instances to reduce obesity-related risks and enable weight loss.State-of-the-art technologies have the potential for long-term benefits in post-surgery living.In this work,an Internet of Things(IoT)framework is proposed to effectively communicate the daily living data and exercise routine of surgery patients and patients with excessive weight.The proposed IoT framework aims to enable seamless communications from wearable sensors and body networks to the cloud to create an accurate profile of the patients.It also attempts to automate the data analysis and represent the facts about a patient.The IoT framework proposes a co-channel interference avoidance mechanism and the ability to communicate higher activity data with minimal impact on the bandwidth requirements of the system.The proposed IoT framework also benefits from machine learning based activity classification systems,with relatively high accuracy,which allow the communicated data to be translated into meaningful information.展开更多
This paper presents a large gathering dataset of images extracted from publicly filmed videos by 24 cameras installed on the premises of Masjid Al-Nabvi,Madinah,Saudi Arabia.This dataset consists of raw and processed ...This paper presents a large gathering dataset of images extracted from publicly filmed videos by 24 cameras installed on the premises of Masjid Al-Nabvi,Madinah,Saudi Arabia.This dataset consists of raw and processed images reflecting a highly challenging and unconstraint environment.The methodology for building the dataset consists of four core phases;that include acquisition of videos,extraction of frames,localization of face regions,and cropping and resizing of detected face regions.The raw images in the dataset consist of a total of 4613 frames obtained fromvideo sequences.The processed images in the dataset consist of the face regions of 250 persons extracted from raw data images to ensure the authenticity of the presented data.The dataset further consists of 8 images corresponding to each of the 250 subjects(persons)for a total of 2000 images.It portrays a highly unconstrained and challenging environment with human faces of varying sizes and pixel quality(resolution).Since the face regions in video sequences are severely degraded due to various unavoidable factors,it can be used as a benchmark to test and evaluate face detection and recognition algorithms for research purposes.We have also gathered and displayed records of the presence of subjects who appear in presented frames;in a temporal context.This can also be used as a temporal benchmark for tracking,finding persons,activity monitoring,and crowd counting in large crowd scenarios.展开更多
With the improvement of seismic observation system, more and more observations indicate that earthquakes may cause seismic velocity change. However, the amplitude and spatial distribution of the velocity variation rem...With the improvement of seismic observation system, more and more observations indicate that earthquakes may cause seismic velocity change. However, the amplitude and spatial distribution of the velocity variation remains a controversial issue. Recent active source monitoring carried out adjacent to Wenchuan Fault Scientific Drilling (WFSD) revealed unambiguous coseismic velocity change associated with a local M8 5.5 earthquake. Here, we carry out forward modeling using two-dimensional spectral element method to further investigate the amplitude and spatial distribution of observed velocity change. The model is well constrained by results from seismic reflection and WFSD coring. Our model strongly suggests that the observed coseismic velocity change is localized within the fault zone with width of ~ 120 m rather than dynamic strong ground shaking. And a velocity decrease of -2.0 % within the fault zone is required to fit the observed travel time delay distribution, which coincides with rock mechanical experiment and theoretical modeling.展开更多
The functional piezoelectric ceramic smart aggregate(SA) sensors and actuators,based on piezoelectric ceramic materials such as lead zirconium titanate(PZT),were embedded into the reinforced concrete beams with three-...The functional piezoelectric ceramic smart aggregate(SA) sensors and actuators,based on piezoelectric ceramic materials such as lead zirconium titanate(PZT),were embedded into the reinforced concrete beams with three-point bending under static loading for purposes of damage detection.The SA actuators generated the desired sine sweep excitation signals online and the SA sensors received and detected real-time signals before and after damage.The wavelet analysis and statistical characteristics about damage signals were used as a signal processing and analysis tool to extract the optimal damage information and establish a statistical damage detection algorithm.The damage index-based wavelet analysis and damage probability-based probability and statistics were proposed by PZT wavebased theory and active health monitoring technology.The results showed that the existence of cracks inside largely attenuated the amplitude of active monitoring signal after the damage of beam and the attenuation was related to the severity degree of damage.The innovative statistical algorithm of damage pattern detection based PZT-SA can effectively determine damage probability and damage degree,and provide a prediction for the critical damage location of reinforced concrete structures.The developed method can be utilized for the structural health comprehensive monitoring and damage detection on line of various large-scale concrete structures.展开更多
The most common method used to describe earthquake activity is based on the changes in physical parameters of the earth's surface such as displacement of active fault and seismic wave.However,such approach is not suc...The most common method used to describe earthquake activity is based on the changes in physical parameters of the earth's surface such as displacement of active fault and seismic wave.However,such approach is not successful in forecasting the movement behaviors of faults.In the present study,a new mechanical model of fault activity,considering the shear strength on the fault plane and the influence of the resistance force,is established based on the occurrence condition of earthquake.A remote real-time monitoring system is correspondingly developed to obtain the changes in mechanical components within fault.Taking into consideration the local geological conditions and the history of fault activity in Zhangjiakou of China,an active fault exposed in the region of Zhangjiakou is selected to be directly monitored by the real-time monitoring technique.A thorough investigation on local fault structures results in the selection of two suitable sites for monitoring potential active tectonic movements of Zhangjiakou fault.Two monitoring curves of shear strength,recorded during a monitoring period of 6 months,turn out to be steady,which indicates that the potential seismic activities hardly occur in the adjacent region in the near future.This monitoring technique can be used for early-warning prediction of the movement of active fault,and can help to further gain an insight into the interaction between fault activity and relevant mechanisms.展开更多
In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a ...In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.展开更多
Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we c...Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we can obtain high-resolution images for the crustal and smaller scale medium.Artificial seismic exploration methods have been widely applied to fields such as展开更多
AIM: To determine the feasibility and potential role of combining radiostereometric analysis(RSA), gait analysis and activity monitoring in the follow-up of fracture patients.METHODS: Two patients with similar 41B3 ti...AIM: To determine the feasibility and potential role of combining radiostereometric analysis(RSA), gait analysis and activity monitoring in the follow-up of fracture patients.METHODS: Two patients with similar 41B3 tibial plateau fractures were treated by open reduction internal fixation augmented with impaction bone grafting and were instructed to partial weight bear to 10 kg for the first six postoperative weeks. Fracture reduction and fixation were assessed by postoperative computer tomographic(CT) scanning. Both patients had tantalum markers inserted intra-operatively to monitor their fracture stability during healing using RSA and differentially loaded RSA(DLRSA) at 6 and 12 wk postoperatively. Gait analyses were performed at 1, 2, 6, and 12 wk postoperatively. Activity monitors were worn for 4 wk between the 2 and 6 wk appointments. In addition to gait analysis, knee function was assessed using the patient reported Lysholm scores, and doctor reported knee range of motion and stability, at 6 and 12 wk postoperatively.RESULTS: There were no complications. CT demonstrated that both fractures were reduced anatomically. Gait analysis indicated that Patient 1 bore weight to 60% of body weight at 2 wk postoperative and 100% at 6 wk. Patient 2 bore weight at 10% of body weight to 6 wk and had very low joint contact forces to that time. At 12 wk however, there was no difference between the gait patterns in the two patients. Patient 1 increased activities of moderate-vigorous intensity from 20 to 60 min/d between 2 and 6 postoperative weeks, whereas Patient 2 remained more stable at 20-30 min/d. The Lysholm scores were similar for both patients and did not improve between 6 and 12 wk postoperatively. DLRSA examination at 12 wk showed that both patients were comfortable to weight bear to 80 kg and under this weight the fractures displaced less than 0.4 mm. RSA measurements demonstrated over time fracture migrations of less than 2 mm in both cases. However, Patient 2, who followed the postoperative weight bearing instructions most closely, displaced less(0.3 mm vs 1.6 mm). CONCLUSION: This study demonstrates the potential of using a combination of RSA, gait analysis and activity monitoring to obtain a comprehensive evidence base for postoperative weight bearing schedules during fracture healing.展开更多
Wearable sensors for activity monitoring currently are being designed and developed,driven by an increasing demand in health care for noninvasive patient monitoring and rehabilitation training.This article reviews sta...Wearable sensors for activity monitoring currently are being designed and developed,driven by an increasing demand in health care for noninvasive patient monitoring and rehabilitation training.This article reviews state-of-the-art wearable sensors for activity monitoring and motion control.Different technologies,including electromechanical,bioelectrical,and biomechanical sensors,are reviewed,along with their broad applications.Moreover,an overview of existing commercial wearable products and the computation methods for motion analysis are provided.Future research issues are identified and discussed.展开更多
Three-dimensional(3D)porous piezoresistive sensors are widely used because of their simple fabrication and convenient signal acquisition.However,because of the dependence on organic skeleton materials and the complexi...Three-dimensional(3D)porous piezoresistive sensors are widely used because of their simple fabrication and convenient signal acquisition.However,because of the dependence on organic skeleton materials and the complexity of conductive coating preparation,the electrical and mechanical properties of 3D wearable piezoresistive sensors have gradually failed to accommodate many emerging fields.Here,a new flexible 3D piezoresistive sensor(NF3PS)with high sensitivity and a wide measurement range is proposed,which comprises a natural porous loofah as a flexible framework and carbon fiber/carbon nanotube(CF/CNT)multiscale composite as a conductive coating.Composed of cellulose and lignin,the irregular,porous loofah has excellent mechanical strength,elasticity,and toughness,ensuring a repeated compression/recovery behavior of the NF3PS.In addition,compared with the single-size carbon coating,the coupling of multiscale CF/CNT composite coating improves sensitivities over a range of pressures.The NF3PS demonstrates a sensitivity of 6.94 kPa^(-1) with good linearity in the pressure range of 0–11.2 kPa and maintains a sensitivity of 0.28 kPa^(-1) in an ultrawide measurement range of 11.2–84.6 kPa.Considering flexibility,robustness,and wide-ranging linear resistance variation,the feasibility of the NF3PS in human activity monitoring,mechanical control,and smart homes is verified.This work provides a novel strategy for a new generation of 3D flexible pressure sensors for improving sensitivity and measurement range and demonstrates attractive applications in wearable sensors.展开更多
A capacitive tactile sensor(CTS)has been developed by assembling a double-sided patterned dielectric layer and novel electrodes.The patterned aluminium foil-supported electrode comprises zinc-aluminium layered double ...A capacitive tactile sensor(CTS)has been developed by assembling a double-sided patterned dielectric layer and novel electrodes.The patterned aluminium foil-supported electrode comprises zinc-aluminium layered double hydroxides(Zn AlLDH),MXene,and Ag NWs via electrostatic interaction.This flexible device enables greater structural deformation,thereby enhancing sensitivity to a wide range of pressure.The sensitivity of the CTS can be customized to meet specific requirements by matching the microstructured electrodes with the patterned dielectric layer.An optimized sensor exhibits a sensitivity of 2.752 kPa^(–1)within 30 kPa,a response time of approximately 100 ms,and a wide detection range of 0–300 kPa.The strong physical interaction among the electrode materials ensures a reliable conductive network,ensuring the long-term stability of the sensor,even after 7500 loading and unloading cycles.Furthermore,the fabricated CTS device presents a promising prospect for the integration into wearable electronics,with the ability to effectively respond to both human activities and external physical stimuli.展开更多
Tyrosine Phosphorylation(pTyr)is a critical and ubiquitous regulation mechanism in biology that plays a central role in controlling intracellular signaling networks.Precise recognition and specific detection of pTyr p...Tyrosine Phosphorylation(pTyr)is a critical and ubiquitous regulation mechanism in biology that plays a central role in controlling intracellular signaling networks.Precise recognition and specific detection of pTyr peptides have been of great importance for both discoveries of disease biomarkers and screening of therapeutic drugs,especially cancers.Here we report a label-free,versatile,realtime,and high-throughput detection strategy for phosphopeptide(PP)based on reversible configuration freeze of a unique hemicyanine-labeled 2-(2′-hydroxyphenyl)-4-methyloxazole(H-HPMO).By taking advantage of the“OFF–ON”transition of fluorescence,H-HPMO–Cu^(2+)complex displays a highly sensitive and selective response to PPs with modified sites on serine,threonine,and tyrosine.Specific recognition of Tyr PPs is achieved by performing a simple logic gate operation and introducing Ca^(2+)interference as an input.This PP detection approach is universal for various peptide sequences and displays high potential in large-scale kinase inhibitor screening,which will promote the development of targeted anticancer drugs.展开更多
The Tianchi volcano in the Changbai Mountains is located on the boundary between China and North Korea.There are many times of eruptions of the Tianchi volcano during the Holocene.One of its large eruptions occurred a...The Tianchi volcano in the Changbai Mountains is located on the boundary between China and North Korea.There are many times of eruptions of the Tianchi volcano during the Holocene.One of its large eruptions occurred around 1000 years ago dated by ^(14)C method and historical records.Composition of products of the largest Tianchi volcanic eruption studied is characterized by comendi-tic Plinian fallout and unwelded ignimbrite,which are mainly distributed in China and North Korea.Caldera is about 4.4 km long and 3.4 km wide,which had filled with water(e.g.Tianchi Lake).The Tianchi volcanic cone is about 2700 m high above sea level.The Tianchi Lake is located on the summit of the volcanic cone,that is also highest peak of the Changbai Mountains in northeastern China.This study analyzed Cl,F,S and H_(2)O concentrations of melt inclusions in the phenocryst min-erals(anorthoclase and quartz)and co-existing matrix glasses using the electron microprobe and estimated environmental effect of Tianchi volcanic gases.The authors proposed a new method to evaluate future eruption of active volcano and estimate potential volcanic hazards based on contents of volatile emissions.Using this method,we made a perspective of future volcanic hazard in this region.展开更多
The ability to track upper extremity movement during activity of daily living has the potential to facilitate the recovery of individuals with neurological or physical injuries. Hence, the use of Surface Electromyogra...The ability to track upper extremity movement during activity of daily living has the potential to facilitate the recovery of individuals with neurological or physical injuries. Hence, the use of Surface Electromyography (sEMG) signals to predict upper extremity movement is an area of interest in the research community. A less established technique, Force Myography (FMG), which uses force sensors to detect forearm muscle contraction patterns, is also able to detect some movements of the arm. This paper investigates the comparative performance of sEMG and FMG when predicting wrist, forearm and elbow positions using signals extracted from the forearm only. Support Vector Machine (SVM) and Linear Discriminant Analysis (LDA) classifiers were used to evaluate the prediction performance of both FMG and sEMG data. Ten healthy volunteers participated in this study. Under a cross validation across a repetition evaluation scheme, the SVM classifier obtained averaged accuracies of 84.3%, 82.4% and 71.0%, respectively, for predicting elbow, forearm and wrist positions using FMG; while sEMG yielded 75.4%, 83.4% and 92.4% accuracies for predicting the same respective positions. The accuracies obtained using SVM are slightly, but statistical significantly, higher than the ones obtained using LDA. However, the trends on the classification performances between FMG and sEMG are consistent. These results also indicate that the forearm FMG pattern is highly influenced by the change of elbow position, while the forearm sEMG is less subjected to the change. Overall, both forearm FMG and sEMG techniques provide abundant information that can be utilized for tracking the upper extremity movements.展开更多
Reservoir-induced earthquakes related with the construction of the Three Gorges Project have attracted great concerns of the public. Since the first water impoundment on May 25, 2003, a number of earthquakes have occu...Reservoir-induced earthquakes related with the construction of the Three Gorges Project have attracted great concerns of the public. Since the first water impoundment on May 25, 2003, a number of earthquakes have occurred during the water storage stages, in which the largest was the Badong M5.1 earthquake on December 16, 2013. In this paper, the relationships between seismic activities, b value, seismic parameters, and reservoir water level fluctuations are studied. In addition, based on the digital seismic waveform data obtained since 2000, the focal depth changes and focal mechanism characteristics before and after the water impoundment are studied as well. These provide us important information to understand the earthquake mechanisms. The results show that these earthquakes are typical reservoir-induced earthquakes, which are closely related to water infiltration, pore pressure, and water level fluctuations.The majority of the micro and small earthquakes are caused by karst collapse, mine collapse, bank reformation, superficial unloading, and so on. The larger earthquakes are related to the fault structures to some extent. Due to the persistent effects of water impoundment on the seismic and geological environments around the reservoir and water infiltration into the rocks, the influences on the crustal deformation field, gravity field, seepage field, and fault medium-softening action may vary gradually from a higher strength to a weaker one. Therefore, it is possible that small earthquakes and few medium earthquakes(M≤5.5) will occur in the reservoir area in the future.展开更多
A one metabolic-equivalent-of-task increase in peak aerobic fitness(peak MET)is associated with a clinically relevant improvement in survival risk and all-cause mortality.The co-dependent impact of free-living physica...A one metabolic-equivalent-of-task increase in peak aerobic fitness(peak MET)is associated with a clinically relevant improvement in survival risk and all-cause mortality.The co-dependent impact of free-living physical behaviours on aerobic fitness are poorly understood.The purpose of this study was to investigate the impact of theoretically re-allocating time spent in physical behaviours on aerobic fitness.We hypothesized that substituting sedentary time with any physical activity(at any intensity)would be associated with a predicted improvement in aerobic fitness.Peak volume rate of oxygen uptake(VO_(2)peak)was assessed via indirect calorimetry during a progressive,maximal cycle ergometer protocol in 103 adults(52 females;[38±21]years;[25.0±3.8]kg/m^(2);VO_(2)peak:[35.4±11.5]ml⋅kg^(-1)⋅min^(-1)).Habitual sedentary time,standing time,light-(LPA),moderate-(MPA),and vigorous-physical activity(VPA)were assessed 24-h/day via thigh-worn inclinometry for up to one week(average:[6.3±0.9]days).Isotemporal substitution modelling examined the impact of replacing one physical behaviour with another.Sedentary time(β=0.8,95%CI:[-1.3,-0.2])and standing time(β=0.9,95%CI:[-1.6,-0.2])were negatively associated with VO_(2)peak,whereas VPA was positively associated with relative VO_(2)peak(β=9.2,95%CI:[0.9,17.6]).Substituting 30-min/day of VPA with any other behaviour was associated with a 2.4–3.4 higher peak MET.Higher standing time was associated with a lower aerobic fitness.As little as 10-min/day of VPA predicted a clinically relevant 0.8–1.1 peak MET increase.Theoretically,replacing any time with relatively small amounts of VPA is associated with improvements in aerobic fitness.展开更多
基金funded by National Scientific and Technological Basic Resources Investigation Program ‘Research and application of nutrition and health system for children aged 0-18 years in China’[2017FY101107]
文摘Objective In this study we aimed to examine the reliability and validity of the wristband activity monitor against the accelerometer for children.Methods A total of 99 children(mean age = 13.0 ± 2.5 y) wore the two monitors in a free-living context for 7 days. Reliability was measured by intraclass correlation to evaluate consistency over time.Repeated-measures analyses of variance was used to detect differences across days. Spearman’s correlation coefficient(rho), median of absolute percentage error, and Bland-Altman analyses were performed to assess the validity of the wristband against the Acti Graph accelerometer. The optimal number of repeated measures for the wristband was calculated by using the Spearman-Brown prophecy formula.Results The wristband had high reliability for all variables, although physical activity data were different across 7 days. A strong correlation for steps(rho: 0.72, P < 0.001), and moderate correlations for time spent on total physical activity(rho: 0.63, P < 0.001) and physical activity energy expenditure(rho: 0.57, P < 0.001) were observed between the wristband and the accelerometer. For different intensities of physical activity, weak to moderate correlations were found(rho: 0.38 to 0.55, P < 0.001).Conclusion The wristband activity monitor seems to be reliable and valid for measurement of overall children’s physical activity, providing a feasible objective method of physical activity surveillance in children.
基金The authors would like to acknowledge the support of the Deputy for Research and Innovation-Ministry of Education,Kingdom of Saudi Arabia,for this research through a grant(NU/IFC/ENT/01/020)under the institutional Funding Committee at Najran University,Kingdom of Saudi Arabia。
文摘Obesity poses several challenges to healthcare and the well-being of individuals.It can be linked to several life-threatening diseases.Surgery is a viable option in some instances to reduce obesity-related risks and enable weight loss.State-of-the-art technologies have the potential for long-term benefits in post-surgery living.In this work,an Internet of Things(IoT)framework is proposed to effectively communicate the daily living data and exercise routine of surgery patients and patients with excessive weight.The proposed IoT framework aims to enable seamless communications from wearable sensors and body networks to the cloud to create an accurate profile of the patients.It also attempts to automate the data analysis and represent the facts about a patient.The IoT framework proposes a co-channel interference avoidance mechanism and the ability to communicate higher activity data with minimal impact on the bandwidth requirements of the system.The proposed IoT framework also benefits from machine learning based activity classification systems,with relatively high accuracy,which allow the communicated data to be translated into meaningful information.
基金This research was supported by the Deanship of Scientific Research,Islamic University of Madinah,Madinah(KSA),under Tammayuz program Grant Number 1442/505.
文摘This paper presents a large gathering dataset of images extracted from publicly filmed videos by 24 cameras installed on the premises of Masjid Al-Nabvi,Madinah,Saudi Arabia.This dataset consists of raw and processed images reflecting a highly challenging and unconstraint environment.The methodology for building the dataset consists of four core phases;that include acquisition of videos,extraction of frames,localization of face regions,and cropping and resizing of detected face regions.The raw images in the dataset consist of a total of 4613 frames obtained fromvideo sequences.The processed images in the dataset consist of the face regions of 250 persons extracted from raw data images to ensure the authenticity of the presented data.The dataset further consists of 8 images corresponding to each of the 250 subjects(persons)for a total of 2000 images.It portrays a highly unconstrained and challenging environment with human faces of varying sizes and pixel quality(resolution).Since the face regions in video sequences are severely degraded due to various unavoidable factors,it can be used as a benchmark to test and evaluate face detection and recognition algorithms for research purposes.We have also gathered and displayed records of the presence of subjects who appear in presented frames;in a temporal context.This can also be used as a temporal benchmark for tracking,finding persons,activity monitoring,and crowd counting in large crowd scenarios.
基金supported by China Natural Scientific and Technological Support Projects(Wenchuan Fault Scientific Drilling)National Natural Scientific Foundation of China(Grant No.41204047)
文摘With the improvement of seismic observation system, more and more observations indicate that earthquakes may cause seismic velocity change. However, the amplitude and spatial distribution of the velocity variation remains a controversial issue. Recent active source monitoring carried out adjacent to Wenchuan Fault Scientific Drilling (WFSD) revealed unambiguous coseismic velocity change associated with a local M8 5.5 earthquake. Here, we carry out forward modeling using two-dimensional spectral element method to further investigate the amplitude and spatial distribution of observed velocity change. The model is well constrained by results from seismic reflection and WFSD coring. Our model strongly suggests that the observed coseismic velocity change is localized within the fault zone with width of ~ 120 m rather than dynamic strong ground shaking. And a velocity decrease of -2.0 % within the fault zone is required to fit the observed travel time delay distribution, which coincides with rock mechanical experiment and theoretical modeling.
基金Supported by Science and Technology Project of Ministry of Housing and Urban-Rural Development(No.2011k211)"11th Five-Year" Science and Technology Research Project of Education Department,Jilin Province(No.200925)Liaoning Structure Engineering Key Laboratory 2009 Open Fund(JG2009 2007-08)
文摘The functional piezoelectric ceramic smart aggregate(SA) sensors and actuators,based on piezoelectric ceramic materials such as lead zirconium titanate(PZT),were embedded into the reinforced concrete beams with three-point bending under static loading for purposes of damage detection.The SA actuators generated the desired sine sweep excitation signals online and the SA sensors received and detected real-time signals before and after damage.The wavelet analysis and statistical characteristics about damage signals were used as a signal processing and analysis tool to extract the optimal damage information and establish a statistical damage detection algorithm.The damage index-based wavelet analysis and damage probability-based probability and statistics were proposed by PZT wavebased theory and active health monitoring technology.The results showed that the existence of cracks inside largely attenuated the amplitude of active monitoring signal after the damage of beam and the attenuation was related to the severity degree of damage.The innovative statistical algorithm of damage pattern detection based PZT-SA can effectively determine damage probability and damage degree,and provide a prediction for the critical damage location of reinforced concrete structures.The developed method can be utilized for the structural health comprehensive monitoring and damage detection on line of various large-scale concrete structures.
文摘The most common method used to describe earthquake activity is based on the changes in physical parameters of the earth's surface such as displacement of active fault and seismic wave.However,such approach is not successful in forecasting the movement behaviors of faults.In the present study,a new mechanical model of fault activity,considering the shear strength on the fault plane and the influence of the resistance force,is established based on the occurrence condition of earthquake.A remote real-time monitoring system is correspondingly developed to obtain the changes in mechanical components within fault.Taking into consideration the local geological conditions and the history of fault activity in Zhangjiakou of China,an active fault exposed in the region of Zhangjiakou is selected to be directly monitored by the real-time monitoring technique.A thorough investigation on local fault structures results in the selection of two suitable sites for monitoring potential active tectonic movements of Zhangjiakou fault.Two monitoring curves of shear strength,recorded during a monitoring period of 6 months,turn out to be steady,which indicates that the potential seismic activities hardly occur in the adjacent region in the near future.This monitoring technique can be used for early-warning prediction of the movement of active fault,and can help to further gain an insight into the interaction between fault activity and relevant mechanisms.
基金Funded by the National Natural Science Foundation of China (No.50708065)the National High-tech R&D Program(863 Program )(No.2007-AA-11-Z-113)the Key Projects in the Science and Technology Pillar Program of Tianjin(No.11ZCKFSF00300)
文摘In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.
文摘Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we can obtain high-resolution images for the crustal and smaller scale medium.Artificial seismic exploration methods have been widely applied to fields such as
文摘AIM: To determine the feasibility and potential role of combining radiostereometric analysis(RSA), gait analysis and activity monitoring in the follow-up of fracture patients.METHODS: Two patients with similar 41B3 tibial plateau fractures were treated by open reduction internal fixation augmented with impaction bone grafting and were instructed to partial weight bear to 10 kg for the first six postoperative weeks. Fracture reduction and fixation were assessed by postoperative computer tomographic(CT) scanning. Both patients had tantalum markers inserted intra-operatively to monitor their fracture stability during healing using RSA and differentially loaded RSA(DLRSA) at 6 and 12 wk postoperatively. Gait analyses were performed at 1, 2, 6, and 12 wk postoperatively. Activity monitors were worn for 4 wk between the 2 and 6 wk appointments. In addition to gait analysis, knee function was assessed using the patient reported Lysholm scores, and doctor reported knee range of motion and stability, at 6 and 12 wk postoperatively.RESULTS: There were no complications. CT demonstrated that both fractures were reduced anatomically. Gait analysis indicated that Patient 1 bore weight to 60% of body weight at 2 wk postoperative and 100% at 6 wk. Patient 2 bore weight at 10% of body weight to 6 wk and had very low joint contact forces to that time. At 12 wk however, there was no difference between the gait patterns in the two patients. Patient 1 increased activities of moderate-vigorous intensity from 20 to 60 min/d between 2 and 6 postoperative weeks, whereas Patient 2 remained more stable at 20-30 min/d. The Lysholm scores were similar for both patients and did not improve between 6 and 12 wk postoperatively. DLRSA examination at 12 wk showed that both patients were comfortable to weight bear to 80 kg and under this weight the fractures displaced less than 0.4 mm. RSA measurements demonstrated over time fracture migrations of less than 2 mm in both cases. However, Patient 2, who followed the postoperative weight bearing instructions most closely, displaced less(0.3 mm vs 1.6 mm). CONCLUSION: This study demonstrates the potential of using a combination of RSA, gait analysis and activity monitoring to obtain a comprehensive evidence base for postoperative weight bearing schedules during fracture healing.
基金supported by the Region Nordjylland Health Hub Project SLAM and the National Natural Science Foundation of China(62073224)the financial support from the China Scholarships Council for her study at Aalborg University,Denmark.
文摘Wearable sensors for activity monitoring currently are being designed and developed,driven by an increasing demand in health care for noninvasive patient monitoring and rehabilitation training.This article reviews state-of-the-art wearable sensors for activity monitoring and motion control.Different technologies,including electromechanical,bioelectrical,and biomechanical sensors,are reviewed,along with their broad applications.Moreover,an overview of existing commercial wearable products and the computation methods for motion analysis are provided.Future research issues are identified and discussed.
基金supported by the National Natural Science Foundation of China(Grant No.52175554)the Natural Science Foundation of Hebei Province(Grant No.F2021409007)+2 种基金the Hebei Province Foundation for the Returned Overseas Chinese Scholars(Grant No.C20220103)the School Research Fund Project(Grant Nos.ZDYY-2021-01,YKY-2022-33)。
文摘Three-dimensional(3D)porous piezoresistive sensors are widely used because of their simple fabrication and convenient signal acquisition.However,because of the dependence on organic skeleton materials and the complexity of conductive coating preparation,the electrical and mechanical properties of 3D wearable piezoresistive sensors have gradually failed to accommodate many emerging fields.Here,a new flexible 3D piezoresistive sensor(NF3PS)with high sensitivity and a wide measurement range is proposed,which comprises a natural porous loofah as a flexible framework and carbon fiber/carbon nanotube(CF/CNT)multiscale composite as a conductive coating.Composed of cellulose and lignin,the irregular,porous loofah has excellent mechanical strength,elasticity,and toughness,ensuring a repeated compression/recovery behavior of the NF3PS.In addition,compared with the single-size carbon coating,the coupling of multiscale CF/CNT composite coating improves sensitivities over a range of pressures.The NF3PS demonstrates a sensitivity of 6.94 kPa^(-1) with good linearity in the pressure range of 0–11.2 kPa and maintains a sensitivity of 0.28 kPa^(-1) in an ultrawide measurement range of 11.2–84.6 kPa.Considering flexibility,robustness,and wide-ranging linear resistance variation,the feasibility of the NF3PS in human activity monitoring,mechanical control,and smart homes is verified.This work provides a novel strategy for a new generation of 3D flexible pressure sensors for improving sensitivity and measurement range and demonstrates attractive applications in wearable sensors.
基金supported by the Natural Science Foundation of Guangdong Province(Grant No.2021A1515010691)the College Innovation Team Project of Guangdong Province(Grant No.2021KCXTD042)+1 种基金the Major Program of Basic Research and Applied Research of Guangdong Province(Grant No.2019KZDXM051)Wuyi University-Hong Kong-Macao Joint Research and Development Fund(Grant Nos.2019WGALH06 and 2021WGALH15)。
文摘A capacitive tactile sensor(CTS)has been developed by assembling a double-sided patterned dielectric layer and novel electrodes.The patterned aluminium foil-supported electrode comprises zinc-aluminium layered double hydroxides(Zn AlLDH),MXene,and Ag NWs via electrostatic interaction.This flexible device enables greater structural deformation,thereby enhancing sensitivity to a wide range of pressure.The sensitivity of the CTS can be customized to meet specific requirements by matching the microstructured electrodes with the patterned dielectric layer.An optimized sensor exhibits a sensitivity of 2.752 kPa^(–1)within 30 kPa,a response time of approximately 100 ms,and a wide detection range of 0–300 kPa.The strong physical interaction among the electrode materials ensures a reliable conductive network,ensuring the long-term stability of the sensor,even after 7500 loading and unloading cycles.Furthermore,the fabricated CTS device presents a promising prospect for the integration into wearable electronics,with the ability to effectively respond to both human activities and external physical stimuli.
基金This work was financially supported by the National Natural Science Foundation of China(grant nos.21775116,21922411,and 21934005)Dalian Institute of Chemical Physics(DICP)Innovation Funding(grant nos.RC201801 and I202008)the LiaoNing Revitalization Talents Program(grant no.XLYC1802109).
文摘Tyrosine Phosphorylation(pTyr)is a critical and ubiquitous regulation mechanism in biology that plays a central role in controlling intracellular signaling networks.Precise recognition and specific detection of pTyr peptides have been of great importance for both discoveries of disease biomarkers and screening of therapeutic drugs,especially cancers.Here we report a label-free,versatile,realtime,and high-throughput detection strategy for phosphopeptide(PP)based on reversible configuration freeze of a unique hemicyanine-labeled 2-(2′-hydroxyphenyl)-4-methyloxazole(H-HPMO).By taking advantage of the“OFF–ON”transition of fluorescence,H-HPMO–Cu^(2+)complex displays a highly sensitive and selective response to PPs with modified sites on serine,threonine,and tyrosine.Specific recognition of Tyr PPs is achieved by performing a simple logic gate operation and introducing Ca^(2+)interference as an input.This PP detection approach is universal for various peptide sequences and displays high potential in large-scale kinase inhibitor screening,which will promote the development of targeted anticancer drugs.
基金supported by the National Natural Science Foundation of China(Grant No.40372045)the Chinese Academy of Sciences(Grant No.KZCX3-SW-145)the Chinese Academy of Sciences(Grant No.KZCX3-SW-145).
文摘The Tianchi volcano in the Changbai Mountains is located on the boundary between China and North Korea.There are many times of eruptions of the Tianchi volcano during the Holocene.One of its large eruptions occurred around 1000 years ago dated by ^(14)C method and historical records.Composition of products of the largest Tianchi volcanic eruption studied is characterized by comendi-tic Plinian fallout and unwelded ignimbrite,which are mainly distributed in China and North Korea.Caldera is about 4.4 km long and 3.4 km wide,which had filled with water(e.g.Tianchi Lake).The Tianchi volcanic cone is about 2700 m high above sea level.The Tianchi Lake is located on the summit of the volcanic cone,that is also highest peak of the Changbai Mountains in northeastern China.This study analyzed Cl,F,S and H_(2)O concentrations of melt inclusions in the phenocryst min-erals(anorthoclase and quartz)and co-existing matrix glasses using the electron microprobe and estimated environmental effect of Tianchi volcanic gases.The authors proposed a new method to evaluate future eruption of active volcano and estimate potential volcanic hazards based on contents of volatile emissions.Using this method,we made a perspective of future volcanic hazard in this region.
文摘The ability to track upper extremity movement during activity of daily living has the potential to facilitate the recovery of individuals with neurological or physical injuries. Hence, the use of Surface Electromyography (sEMG) signals to predict upper extremity movement is an area of interest in the research community. A less established technique, Force Myography (FMG), which uses force sensors to detect forearm muscle contraction patterns, is also able to detect some movements of the arm. This paper investigates the comparative performance of sEMG and FMG when predicting wrist, forearm and elbow positions using signals extracted from the forearm only. Support Vector Machine (SVM) and Linear Discriminant Analysis (LDA) classifiers were used to evaluate the prediction performance of both FMG and sEMG data. Ten healthy volunteers participated in this study. Under a cross validation across a repetition evaluation scheme, the SVM classifier obtained averaged accuracies of 84.3%, 82.4% and 71.0%, respectively, for predicting elbow, forearm and wrist positions using FMG; while sEMG yielded 75.4%, 83.4% and 92.4% accuracies for predicting the same respective positions. The accuracies obtained using SVM are slightly, but statistical significantly, higher than the ones obtained using LDA. However, the trends on the classification performances between FMG and sEMG are consistent. These results also indicate that the forearm FMG pattern is highly influenced by the change of elbow position, while the forearm sEMG is less subjected to the change. Overall, both forearm FMG and sEMG techniques provide abundant information that can be utilized for tracking the upper extremity movements.
基金supported by the National Natural Science Foundation of China (41572354)the Key Foundation of the Institute of Seismology (IS201616254)
文摘Reservoir-induced earthquakes related with the construction of the Three Gorges Project have attracted great concerns of the public. Since the first water impoundment on May 25, 2003, a number of earthquakes have occurred during the water storage stages, in which the largest was the Badong M5.1 earthquake on December 16, 2013. In this paper, the relationships between seismic activities, b value, seismic parameters, and reservoir water level fluctuations are studied. In addition, based on the digital seismic waveform data obtained since 2000, the focal depth changes and focal mechanism characteristics before and after the water impoundment are studied as well. These provide us important information to understand the earthquake mechanisms. The results show that these earthquakes are typical reservoir-induced earthquakes, which are closely related to water infiltration, pore pressure, and water level fluctuations.The majority of the micro and small earthquakes are caused by karst collapse, mine collapse, bank reformation, superficial unloading, and so on. The larger earthquakes are related to the fault structures to some extent. Due to the persistent effects of water impoundment on the seismic and geological environments around the reservoir and water infiltration into the rocks, the influences on the crustal deformation field, gravity field, seepage field, and fault medium-softening action may vary gradually from a higher strength to a weaker one. Therefore, it is possible that small earthquakes and few medium earthquakes(M≤5.5) will occur in the reservoir area in the future.
文摘A one metabolic-equivalent-of-task increase in peak aerobic fitness(peak MET)is associated with a clinically relevant improvement in survival risk and all-cause mortality.The co-dependent impact of free-living physical behaviours on aerobic fitness are poorly understood.The purpose of this study was to investigate the impact of theoretically re-allocating time spent in physical behaviours on aerobic fitness.We hypothesized that substituting sedentary time with any physical activity(at any intensity)would be associated with a predicted improvement in aerobic fitness.Peak volume rate of oxygen uptake(VO_(2)peak)was assessed via indirect calorimetry during a progressive,maximal cycle ergometer protocol in 103 adults(52 females;[38±21]years;[25.0±3.8]kg/m^(2);VO_(2)peak:[35.4±11.5]ml⋅kg^(-1)⋅min^(-1)).Habitual sedentary time,standing time,light-(LPA),moderate-(MPA),and vigorous-physical activity(VPA)were assessed 24-h/day via thigh-worn inclinometry for up to one week(average:[6.3±0.9]days).Isotemporal substitution modelling examined the impact of replacing one physical behaviour with another.Sedentary time(β=0.8,95%CI:[-1.3,-0.2])and standing time(β=0.9,95%CI:[-1.6,-0.2])were negatively associated with VO_(2)peak,whereas VPA was positively associated with relative VO_(2)peak(β=9.2,95%CI:[0.9,17.6]).Substituting 30-min/day of VPA with any other behaviour was associated with a 2.4–3.4 higher peak MET.Higher standing time was associated with a lower aerobic fitness.As little as 10-min/day of VPA predicted a clinically relevant 0.8–1.1 peak MET increase.Theoretically,replacing any time with relatively small amounts of VPA is associated with improvements in aerobic fitness.