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New threats are a challenge for the design and manufacture of modern combat helmets. These helmets must satisfy a wide range of impact velocities from ballistic impacts to blunt impacts. In this paper, we analyze European Regulation ECE R22.05 using a standard surrogate head and a human head model to evaluate combat helmet performance. Two critical parameters on traumatic brain analysis are studied for different impact locations, i.e., peak linear acceleration value and head injury criterion (HIC). The results obtained are compared with different injury criteria to determine the severity level of damage induced. Furthermore, based on different impact scenarios, analyses of the influence of impact velocity and the geometry impact surface are performed. The results show that the risks associated with a blunt impact can lead to a mild traumatic brain injury at high impact velocities and some impact locations, despite satisfying the different criteria established by the ECE R22.05 standard. The results reveal that the use of a human head for the estimation of brain injuries differs slightly from the results obtained using a surrogate head. Therefore, the current combat helmet configuration must be improved for blunt impacts. Further standards should take this into account and, consequently, combat helmet manufacturers on their design process. [ABSTRACT FROM AUTHOR]

In recent years, penetrating weapons have been used more and more to attack increasingly hard targets; therefore, the impact of such a penetrating process has increased to an extremely high level. As an important component of a fuze, the reliability of the ceramic capacitor in high-impact environments is key for the normal working of the fuze. In this paper, we found that a high-impact causes parameter drift of the multilayer ceramic capacitor (MLCC), which further causes the fuze to misfire. This paper mainly studies the internal mechanism of the MLCC's parameter drift during high impact. Firstly, transient physical phenomena, such as capacitance fluctuation and the leakage current increase of the ceramic capacitor under a high acceleration impact, were studied experimentally by a Machete hammer, revealing the relationship between the capacitance change, leakage current change, and acceleration under different working conditions. Secondly, a mechanical model of the ceramic capacitor is established to simulate the change in capacitance value, which shows that the main factor of the capacitance change is the deformation-derived change in the facing area between the electrodes. Lastly, an equivalent circuit model is established to simulate the change in the leakage current, which shows that the main factor of the leakage current change is the piezoelectric resistance of the ceramic dielectric. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study of the effectiveness of constrained vibration damping coatings comprising a thin polymer layer with a very high damping capacity and thin constraining layers of various thickness. Vibration analysis of steel plates with and without a coating on the plate surface was performed. It was shown that the application of the investigated coating significantly reduced the vibration and sound generation in plate elements of structures. [ABSTRACT FROM AUTHOR]

Structural health monitoring has been utilized in numerous ways to investigate the performance and integrity of highway bridges. This paper highlights the use of six structural health monitoring systems, which were deployed to monitor distinct behaviors on six bridges in Kentucky. The structural health monitoring systems are as follows: (1) Over-height truck impact detection and monitoring on the I-64 over US 60 bridge, (2) Barge impact detection and monitoring on northbound US 41 over the Ohio River, (3) effectiveness of carbon fiber-reinforced polymer retrofit evaluation based on prestressed concrete I-girder crack movement on the I-65 elevated expressway in Louisville, (4) effect of thermal loads on bridge substructure evaluation on KY 100 over Trammel Creek, (5) thermal movement of expansion joints evaluation on eastbound I-24 over the Tennessee River, and (6) crack growth monitoring on steel floor beam on I-275 over the Ohio River. The deployment of the different structural health monitoring systems on Kentucky bridges has provided valuable insights on their planning, implementation, and maintenance, which can be applied on future structural health monitoring projects. While several of the projects have proved immensely successful, with some still being continuously monitored, others, due to numerous complications, have met with only limited success. The best return on investment was realized from structural health monitoring instrumentation that was focused and limited in scope. The successful structural health monitoring systems had continuous communication between all stakeholders during planning, implementation, and monitoring phases of the projects. Following implementation, the availability of contingency funds through the funding source, to replace/upgrade sensors and networking equipment and costs for reprogramming and reinstallation outside of regular maintenance costs, was also important for the structural health monitoring to be successful. [ABSTRACT FROM AUTHOR]

The use of a single method of acceleration threshold discrimination cannot fully characterize the change in human fall behavior, which can easily result in misjudgment. In this paper, we propose a human fall detection algorithm that combines human posture, support vector machine (SVM), and quadratic threshold decision. Firstly, a large number of human posture data are collected through a six-axis inertial measurement module (MPU6050). A fall detection model is established through filtering preprocessing, eigenvalue extraction, classification, and SVM training. Secondly, a first-level threshold determination is performed through a wearable wristband device. When a suspected fall occurs, six eigenvalues will be captured and uploaded to a cloud platform to trigger second-level SVM fall judgments. By matching the eigenvalues with the fall detection model, it can be determined accurately whether a fall has taken place. The experimental results show that the fall detection has a recognition rate of 92.2%, a false rate of 3.593%, and missing rate of 2.187%, which can better distinguish other nonfall actions. [ABSTRACT FROM AUTHOR]

In this work, to evaluate the influence of the threshold on the dynamic contact process, five models (number 1, 2, 3, 4, 5) with different thresholds were proposed and fabricated with surface micromachining technology. The contact time and response time were used to characterize the dynamic contact performance. The dynamic contact processes of the inertial switches with gradually increasing thresholds were researched using analytical, simulation, and experimental methods. The basic working principle analysis of the inertial switch shows that the contact time of the inertial switch with a low-g value can be extended by using a simply supported beam as the fixed electrode, but the high-G inertial needs more elasticity for fixed electrode. The simulation results indicate that the response time and contact time decrease with the increment in the designed threshold. Prototypes were tested using a dropping hammer system, and the test result indicates that the contact time of the inertial switch with a fixed electrode of the simply supported beam is about 15 and 5 μs when the threshold is about 280 and 580 g, respectively. Meanwhile, the contact time can be extended to 100 μs for the inertial switch using a spring as the fixed electrode when the threshold is about 280 and 580 g. These test results not only prove that the spring fixed electrode can effectively extend the contact time, but also prove that the style of the fixed electrode is the deciding factor affecting the contact time of the high-G inertial switch. [ABSTRACT FROM AUTHOR]

Assessing the behavior of earth dams under dynamic loads is one of the most significant problems with the design of such large structures. The purpose of this study is to provide new models for predicting dam dispersion in real earthquake conditions. In the first phase, 103 real cases of deformation in earth dams were collected and analyzed due to earthquakes that occurred over recent years. Using nonlinear and machine learning techniques, i.e., group method of data handling (GMDH) and multivariate adaptive regression splines (MARS), two models for prediction of the slope deformation in earth dams under the various types of earthquakes were applied and developed. The main parameters used in these simulation techniques were earthquake magnitude (Mw), fundamental period ratio (Td/Tp), yield acceleration ratio (ay/amax) as inputs and value of slope deformation (Dave) as output. Finally, in order to check the accuracy of the results of the new models, a comparison was made with the previous relations and models in seismic conditions for the slope deformation in earth dams. The results showed that the MARS model, which is able to provide a mathematical equation, has a better result than the GMDH model. These new models are recommended to be used for future analyses based on their flexible capabilities. [ABSTRACT FROM AUTHOR]

The lateral vibration serviceability of slender footbridges has been the subject of many studies over the last few decades. However, in spite of the large amount of research, a common criterion has not been set yet. Although the human–structure interaction phenomenon is widely accepted as the main cause of the sudden onset of high amplitudes of vibration, the current design recommendations do not include an expression for the auto-induced component of the pedestrian action and, as a consequence, it is not possible to evaluate the footbridge comfort once the lock-in effect has developed. Hence, the purpose of this paper is to propose a general formulation, which allows the analysis of the different load scenarios that the footbridge will experience during its overall life cycle. An important advantage over most current design guidelines is that the procedure permits the evaluation of the comfort level of the footbridge, even with crowd densities above the "critical number", and thus takes informed decisions about the possible use of external devices to control the vibration response, depending on the probability of occurrence of the problem. The performance of the proposed method is successfully evaluated through numerical response simulations of two real footbridges, showing a good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Life on Earth has evolved under the influence of gravity. This force has played an important role in shaping development and morphology from the molecular level to the whole organism. Although aquatic life experiences reduced gravity effects, land plants have evolved under a 1- g environment. Understanding gravitational effects requires changing the magnitude of this force. One method of eliminating gravity''s influence is to enter into a free-fall orbit around the planet, thereby achieving a balance between centripetal force of gravity and the centrifugal force of the moving object. This balance is often mistakenly referred to as microgravity, but is best described as weightlessness. In addition to actually compensating gravity, instruments such as clinostats, random-positioning machines (RPM), and magnetic levitation devices have been used to eliminate effects of constant gravity on plant growth and development. However, these platforms do not reduce gravity but constantly change its direction. Despite these fundamental differences, there are few studies that have investigated the comparability between these platforms and weightlessness. Here, we provide a review of the strengths and weaknesses of these analogs for the study of plant growth and development compared to spaceflight experiments. We also consider reduced or partial gravity effects via spaceflight and analog methods. While these analogs are useful, the fidelity of the results relative to spaceflight depends on biological parameters and environmental conditions that cannot be simulated in ground-based studies. [ABSTRACT FROM AUTHOR]

Monitoring concerned activities and identifying activity types usually require sensors and corresponding data processing circuits, which are often restricted by the limited power supply in wireless sensor networks (WSNs). This study presents a self-powered smart WSN for passively monitoring and distinguishing different vibration events. In the proposed WSN, the sensing function is performed by vibration-threshold-triggered energy harvesters (VTT-EHs). The output power of the VTT-EH dramatically increases when an input vibration exceeds the pre-set vibration-threshold of the harvester, indicating the occurrence of specific concerned events. On the basis of this principle, two VTT-EHs with different thresholds were designed to detect and distinguish vibration events with different vibration characteristics. Meanwhile, electromagnetic EHs were applied to generate sufficient power for wirelessly transmitting the alarm signals within several seconds. The prototype of the proposed WSN was developed and evaluated. The sensor node was able to identify two types of intrusive activities: weak shake and strong knock. The alarming signals were first sent to a router node and then transmitted to a mobile phone through the global system of mobile communication network. The mobile phone received the alarming text messages with correct event type within 2 s after the excitation occurred. [ABSTRACT FROM AUTHOR]

In human quiet standing, the relative position between ankle joint centre and line of gravity is neurally regulated within tight limits. The regulation of the knee and hip configuration is unclear and thought to be controlled passively. However, perturbed standing experiments have shown a lower limb multi-joint coordination. Here, measuring the relative alignment between lower limb joints and the line of gravity in quiet standing after walking, we investigated whether the configuration is maintained over time through passive mechanisms or active control. Thirteen healthy adults walked without following a path and then stood quietly for 7.6 s on a force platform (up to four trials). The transition between initiation and steady-state standing (7.6 s) was measured using motion capture. Sagittal lower limb joint centres' position relative to line of gravity (CoGAP) and their time constants were calculated in each trial. Ankle, knee, and hip joint moments were also calculated through inverse dynamics. After walking, the body decelerated (τ = 0.16 s). The ankle and hip joints' position relative to CoGAP measured at two time intervals of quiet standing (Mid = 0.5–0.55 s; End = 7.55–7.6 s) were different (mean ± SEM, CoGAP–Ankle_Mid = 47 ± 4 mm, CoGAP–Ankle_End = 58 ± 5 mm; CoGAP–Hip_Mid = 2 ± 5 mm, CoGAP–Hip_End = −5 ± 5 mm). The ankle, knee, and hip flexion-extension moments significantly changed. Changes in joints position relative to CoGAP and misalignment suggest that joint position is not maintained over 7.6 s, but regulated relative to a standing reference. Higher joint moments at steady-state standing suggest mechanisms other than passive knee and hip regulation are involved in standing. [ABSTRACT FROM AUTHOR]

An omnidirectional inertial switch with rectangular spring is proposed in this paper, and the prototype has been fabricated by surface micromachining technology. To evaluate the threshold consistency and stability of omnidirectional inertia switch, the stiffness of rectangular suspension springs is analyzed. The simulation result shows that the coupling stiffness of the rectangular spring suspension system in the non-sensitive direction is a little more than that in the sensitive direction, which indicated that the omnidirectional switching system’s stability is reinforced, attributed to the design of rectangular springs. The dynamic response simulation shows that the threshold of the omnidirectional inertial switch using the rectangular suspension spring has high consistency in the horizontal direction. The prototype of an inertial switch is fabricated and tested successfully. The testing results indicate even threshold distribution in the horizontal direction. The threshold acceleration of the designed inertial switch is about 58 g in the X direction and 37 g in the Z direction; the contact time is about 18 μs.

Additive Manufacturing (AM) of three-dimensional objects is now being progressively realised with its ad-hoc approach with minimal material wastage (lean manufacturing) being one of its benefit by default. It could also be considered as an evolutional paradigm in the manufacturing industry with its long list of application as of late. Artificial Intelligence is currently finding its usefulness in predictive modelling to provide intelligent, efficient, customisable, high-quality and sustainable-oriented production process. This paper presents a comprehensive survey on commonly used predictive models based on heuristic algorithms and discusses their applications toward making AM “smart”. This paper summarises AM’s current trend, future opportunity, gaps, and requirements together with recommendations for technology and research for inter-industry collaboration, educational training and technology transfer in the AI perspective in-line with the Industry 4.0 developmental process. Moreover, machine learning algorithms are presented for detecting product defects in the cyber-physical system of additive manufacturing. Based on reviews on various applications, printability with multi-indicators, reduction of design complexity threshold, acceleration of prefabrication, real-time control, enhancement of security and defect detection for customised designs are seen of as prospective opportunities for further research.

The engine is in a dynamic state when vehicles in the starting,parking,braking and shifting.The optimal shift point is different from the ones designed in steady state. The neural network method is used to establish the dynamic model of the engine and the model is trained with the experimental data. Based on this model,three-parameter shift schedule including vehicle speed,throttle threshold,acceleration of the mining truck is designed. A dynamics model of the vehicle is established by MATLAB/Sim Driveline,the power performance of the designed shift schedule is verified by simulation analysis. This method can be used to modify the existing two-parameter shift schedule of the mining truck.

In active mountain belts with steep terrain, bedrock landsliding is a major erosional agent. In the Himalayas, landsliding is driven by annual hydro-meteorological forcing due to the summer monsoon and by rarer, exceptional events, such as earthquakes. Independent methods yield erosion rate estimates that appear to increase with sampling time, suggesting that rare, high-magnitude erosion events dominate the erosional budget. Nevertheless, until now, neither the contribution of monsoon and earthquakes to landslide erosion nor the proportion of erosion due to rare, giant landslides have been quantified in the Himalayas. We address these challenges by combining and analysing earthquake- and monsoon-induced landslide inventories across different timescales. With time series of 5 m satellite images over four main valleys in central Nepal, we comprehensively mapped landslides caused by the monsoon from 2010 to 2018. We found no clear correlation between monsoon properties and landsliding and a similar mean landsliding rate for all valleys, except in 2015, where the valleys affected by the earthquake featured ∼5 –8 times more landsliding than the pre-earthquake mean rate. The long-term size–frequency distribution of monsoon-induced landsliding (MIL) was derived from these inventories and from an inventory of landslides larger than ∼0.1 km 2 that occurred between 1972 and 2014. Using a published landslide inventory for the Gorkha 2015 earthquake, we derive the size–frequency distribution for earthquake-induced landsliding (EQIL). These two distributions are dominated by infrequent, large and giant landslides but under-predict an estimated Holocene frequency of giant landslides (> 1 km 3) which we derived from a literature compilation. This discrepancy can be resolved when modelling the effect of a full distribution of earthquakes of variable magnitude and when considering that a shallower earthquake may cause larger landslides. In this case, EQIL and MIL contribute about equally to a total long-term erosion of ∼2±0.75 mm yr -1 in agreement with most thermo-chronological data. Independently of the specific total and relative erosion rates, the heavy-tailed size–frequency distribution from MIL and EQIL and the very large maximal landslide size in the Himalayas indicate that mean landslide erosion rates increase with sampling time, as has been observed for independent erosion estimates. Further, we find that the sampling timescale required to adequately capture the frequency of the largest landslides, which is necessary for deriving long-term mean erosion rates, is often much longer than the averaging time of cosmogenic 10Be methods. This observation presents a strong caveat when interpreting spatial or temporal variability in erosion rates from this method. Thus, in areas where a very large, rare landslide contributes heavily to long-term erosion (as the Himalayas), we recommend 10Be sample in catchments with source areas > 10 000 km 2 to reduce the method mean bias to below ∼20 % of the long-term erosion. [ABSTRACT FROM AUTHOR]

The current trend toward longer spans and lighter floor systems, combined with reduced damping and new activities, have resulted in an increasing complaints on floor vibration from building owners and occupants. Heel-drop, jumping, and walking impacts, which may lead to discomfort problems in daily life, were imposed on a large-span arched prestressed concrete truss (APT) girder system studied. The natural frequencies, peak acceleration, average root-mean-square acceleration (ARMS), maximum transient vibration value (MTVV), and perception factor for the girder were obtained and checked against the existing codes and standards. The purpose of this paper is to provide researchers and engineers with a detailed evaluation on the vibration behavior of the APT girder under different human activities, with a comprehensive review on the relevant criteria and some suggestions. Lastly, the following threshold peak accelerations are suggested: 650 mm/s2 for transient heel-drop impact, 1450 mm/s2 for transient jumping impact, and 250 mm/s2 for steady-state walking. In addition, the threshold values of 90 mm/s2 and 50 mm/s2 are suggested for MTVV and ARMS, respectively, under steady-state walking. [ABSTRACT FROM AUTHOR]

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Abstract: We compiled damages to hydropower projects (HPPs) in the wake of Nepal's 2015 Gorkha earthquake and its main aftershock. Based on 41 records of HPP losses, we identify the main mechanisms determining the degree of loss. We show that, among these mechanisms, earthquake‐triggered landslides had the largest share. Landslides clustered where peak ground acceleration and river steepness Mχ, a metric frequently used in tectonic geomorphology, attain high values. A Bayesian logistic regression reveals that both metrics are credible predictors for HPP damage states. Our study underscores the vulnerability of Himalayan hydropower to landsliding. We estimate that ~25% of existing, currently constructed, and planned HPPs and >10% of potential HPP sites along Himalayan rivers have high probabilities of moderate to severe damage during future earthquake. Our study highlights that HPP hazard assessments need to consider both seismic and the geomorphic setting of HPP sites conjunctively. [ABSTRACT FROM AUTHOR]

This paper presents the development of a lumped-parameter model of multistory framed shear buildings supporting rigid blocks with the possibility to slide. After favorably comparing with results from finite-element analyses and shake table tests, the model was used to assess design provisions in regard to the treatment of live load as seismic weight. It was found that using the minimum live load percentage in current design standards may lead to unconservative drift estimates for buildings supporting heavy and nearly permanent live load objects and structures that are (1) designed for higher R values, (2) located in regions of low-to-moderate seismic risk, or (3) base isolated. Results from a parametric study led to a design expression that allows determining the portion of the expected live load that is effective as seismic weight on the structure as a function of the object/floor interface's friction coefficient and the maximum floor acceleration of the building alone. The adequacy of the design expression was confirmed through three-dimensional finite-element analyses of two- and four-story buildings supporting live load objects that could slide. [ABSTRACT FROM AUTHOR]

Geoengineering activities such as reservoir impoundment, mining, wastewater injection, geothermal systems, and CO2 capture have been linked directly to induced seismicity. With the industrial boom in natural shale gas production regions previously aseismic areas have seen an exponential growth in the frequency of small magnitude events, with multiple events observed in close proximity within a 24-hour time period. While the overwhelming majority of induced seismic research has focused on the causality, the potential risk posed to critical federal infrastructure has escaped scrutiny. This proposes the question, “Can repetitive small magnitude-induced seismic events actually cause damage?” A review of the potential risk is presented herein, concluding that a simplistic definitive statement of whether single or multiple small magnitude-induced seismic events do or do not cause damage to critical infrastructure cannot be justified, and warrants additional study. However, recent observations and research suggest the likelihood that these geoengineering-induced events can and do cause detrimental degradation of the subsurface (damaging the overlying structure) is not insignificant. [ABSTRACT FROM AUTHOR]

Eco-driving is an effective means to reduce vehicle fuel consumption. Although many researches and devices have been developed to introduce eco-driving, quantitative effects of driver behaviors on fuel consumption are still unclear, as well as quantitative eco-driving advices. To solve this problem and promote the application of eco-driving in China, a driving-events-based eco-driving behavior evaluation model was proposed in this paper. First, based on taxicab operating data, the relationship between three vehicle operating parameters (speed, acceleration, and driving mode duration) and fuel consumption was analyzed. Then, nine fuel-consumption-involved driving events (including Accelerating Sharply, Decelerating Sharply, and Long-Time Accelerating) were proposed and defined. Using the frequency of each driving event in a certain distance as independent variable and vehicle fuel consumption as dependent variable, principal component analysis (PCA) and multiple linear regression were applied to establish driver’s eco-driving behavior evaluation model. The model was proved to be highly accurate (96.72%). At last, based on the evaluation model, corresponding quantitative eco-driving advices were provided to help driver to improve their driving skills. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study on the deterministic and probabilistic serviceability assessment of footbridge vibrations due to a single walker crossing. The dynamic response of the footbridge is analyzed by means of modal analysis, considering only the first lateral and vertical modes. Single span footbridges with uniform mass distribution are considered, with different values of the span length, natural frequencies, mass, and structural damping and with different support conditions. The load induced by a single walker crossing the footbridge is modeled as a moving sinusoidal force either in the lateral or in the vertical direction. The variability of the characteristics of the load induced by walkers is modeled using probability distributions taken from the literature defining a Standard Population of walkers. Deterministic and probabilistic approaches were adopted to assess the peak response. Based on the results of the simulations, deterministic and probabilistic vibration serviceability assessment methods are proposed, not requiring numerical analyses. Finally, an example of the application of the proposed method to a truss steel footbridge is presented. The results highlight the advantages of the probabilistic procedure in terms of reliability quantification. [ABSTRACT FROM AUTHOR]

An efficient methodology is proposed for simulation of roll dynamics of a tank vehicle system coupled with transient hydrodynamic forces due to fluid slosh. The transient fluid slosh in a horizontal cylindrical tank is analytically modeled considering simultaneous lateral, vertical and roll excitations assuming potential flows and a linearized free-surface boundary condition. For this purpose, the fluid domain in the Cartesian coordinate system is transformed to the bipolar coordinates, where the Laplace equation could be solved using separation of variables. The resulting hydrodynamic pressure, free-surface elevation and slosh force and roll moment are formulated in the tank-fixed coordinate system. The transient fluid slosh model is subsequently integrated to a dynamic roll plane model of a tank vehicle combination to investigate the effect of transient liquid slosh on the roll stability of the vehicle during steady-turning as well as path-change maneuvers. The analyses are performed for different fluid fill heights considering both variable and constant cargo load conditions. The results suggest that the roll stability of tank vehicles can be efficiently analyzed using the coupled linear slosh and multi-body vehicle models with significantly lower computational effort than the methods employing computational fluid dynamic fluid slosh models. [ABSTRACT FROM AUTHOR]

Two experiments were conducted on an upright and a grand piano, both either producing string vibrations or conversely being silent after the initial keypress, while pianists were listening to the feedback from a synthesizer through insulating headphones. In a quality experiment, participants unaware of the silent mode were asked to play freely and then rate the instrument according to a set of attributes and general preference. Participants preferred the vibrating over the silent setup, and preference ratings were associated to auditory attributes of richness and naturalness in the low and middle ranges. Another experiment on the same setup measured the detection of vibrations at the keyboard, while pianists played notes and chords of varying dynamics and duration. Sensitivity to string vibrations was highest in the lowest register and gradually decreased up to note D5. After the percussive transient, the tactile stimuli exhibited spectral peaks of acceleration whose perceptibility was demonstrated by tests conducted in active touch conditions. The two experiments confirm that piano performers perceive vibratory cues of strings mediated by spectral and spatial summations occurring in the Pacinian system in their fingertips, and suggest that such cues play a role in the evaluation of quality of the musical instrument. [ABSTRACT FROM AUTHOR]

Independent living of elderly persons in their homes requires support that can be provided with modern assistive technologies. Monitoring of elderly persons behaviour delivers valuable information that can be used for diagnosis and detection of health problems as well as triggering alerts in emergency situations. The paper includes a description of the ultra wideband system developed within Networked InfrasTructure for Innovative home Care Solutions (NITICS) Active and Assisted Living (AAL) project. The system can be used as a component of AAL platforms. It delivers data on users localization and has a fall detector functionality. The system also provides access to raw measurement results from Microelectromechanical Systems (MEMS) sensors embedded in the device worn by the monitored person. These data can be used in solutions intended for elderly person’s behaviour investigation. The system was investigated under laboratory conditions as well as in home environment. The detailed system description and results of performed tests are included in the article. [ABSTRACT FROM AUTHOR]

In this study, a novel dual implementation of the Kalman filter proposed by Eftekhar Azam et al. (2014, 2015) is experimentally validated for simultaneous estimation of the states and input of structural systems. By means of numerical simulations, it has been shown that the proposed method outperforms existing techniques in terms of robustness and accuracy for the estimated displacement and velocity time histories. Herein, dynamic response measurements, in the form of displacement and acceleration time histories from a small-scale laboratory building structure excited at the base by a shake table, are considered for evaluating the performance of the proposed Dual Kalman filter and in order to compare this with available alternatives, such as the augmented Kalman filter (Lourens et al., 2012b) and the Gillijn De Moore filter (GDF) (2007b). The suggested Bayesian approach requires the availability of a physical model of the system in addition to output-only measurements from limited degrees of freedom. Two categories of such physical models are herein studied to evaluate the effect of model error on the filter performances; the first, is a model that comprises identified modal parameters, i.e., natural frequencies, mode shapes, modal damping ratios and modal participation factors; the second, is a model that is extracted from a recently developed subspace identification procedure, namely the transformed stochastic subspace identification method. The results are encouraging for the further use of the dual Kalman filter and its available alternatives for addressing the important problems of full response reconstruction and fatigue estimation in the entire body of linear structures, using a limited number of output-only vibration measurements. [ABSTRACT FROM AUTHOR]

We present an analytical, seismologically consistent expression for the surface area of the region within which most landslides triggered by an earthquake are located (landslide distribution area). This expression is based on scaling laws relating seismic moment, source depth, and focal mechanism with ground shaking and fault rupture length and assumes a globally constant threshold of acceleration for onset of systematic mass wasting. The seismological assumptions are identical to those recently used to propose a seismologically consistent expression for the total volume and area of landslides triggered by an earthquake. To test the accuracy of the model we gathered geophysical information and estimates of the landslide distribution area for 83 earthquakes. To reduce uncertainties and inconsistencies in the estimation of the landslide distribution area, we propose an objective definition based on the shortest distance from the seismic wave emission line containing 95% of the total landslide area. Without any empirical calibration the model explains 56% of the variance in our dataset, and predicts 35 to 49 out of 83 cases within a factor of 2, depending on how we account for uncertainties on the seismic source depth. For most cases with comprehensive landslide inventories we show that our prediction compares well with the smallest region around the fault containing 95% of the total landslide area. Aspects ignored by the model that could explain the residuals include local variations of the threshold of acceleration and processes modulating the surface ground shaking, such as the distribution of seismic energy release on the fault plane, the dynamic stress drop, and rupture directivity. Nevertheless, its simplicity and first-order accuracy suggest that the model can yield plausible and useful estimates of the landslide distribution area in near-real time, with earthquake parameters issued by standard detection routines. [ABSTRACT FROM AUTHOR]

The paper compares two liquefaction case histories in California: (1) the response of the Wildlife site in the Imperial Valley to the 2010 El-Mayor Cucapah earthquake (Mw = 7.2, amax = 0.15 g); and (2) the response of the Treasure Island Fire Station (F.S.) site in the San Francisco Bay area to the 1989 Loma Prieta earthquake (Mw = 6.9, amax = 0.16 g). Both histories involve silty sand critical layers with nonplastic fines contents, FC = 24-27%, similar normalized shear wave velocities, Vs1 = 145-155 m/s, low cone penetration test (CPT) cone penetration resistances, and groundwater tables at essentially the same depth. The corresponding data points plot almost on top of each other on the shear wave velocity field liquefaction charts, which predict liquefaction at both sites. While Treasure Island F.S. did liquefy during the shaking, Wildlife did not and was far from liquefaction as indicated by piezometers at the site. This paper constitutes an attempt to understand the reason for these very different pore pressure responses through a detailed analysis of similarities and differences between the two histories. It is concluded that preshaking by previous earthquakes is the most probable explanation of the higher liquefaction resistance exhibited by the Wildlife site and other sites in the Imperial Valley. While the Wildlife critical layer was subjected to about 60-70 earthquakes capable of generating significant excess pore pressures between its estimated 1907 deposition and the 2010 earthquake, the Treasure Island F.S. layer was subjected to only about two earthquakes capable of doing so between deposition in the 1930's and the 1989 earthquake. This difference is due to the very high seismic activity in the last 100-plus years in the Imperial Valley compared with a seismically quiet San Francisco Bay Area after the 1906 earthquake. The significance of the prior seismic history is corroborated by recent results from centrifuge and large-scale experiments. These results as well as the methodology developed in the paper may be helpful when analyzing the observed high liquefaction resistance of sandy sites located in other seismic regions. [ABSTRACT FROM AUTHOR]

This paper studies the size-dependent dynamic behavior of electrostatically actuated microaccelerometers using the modified couple stress theory. The device is modeled as a cantilevered microbeam with an electrostatically actuated proof mass attached to its free end. The equation of motion is derived based on the Hamilton's principle and solved both numerically (using the finite element and finite difference methods) and analytically (using the perturbation technique) and the dynamic response and pull-in instability of the device is studied. The results of these methods are compared and the source of error in the analytical results at high values of external acceleration is discussed. Furthermore, the results are compared with those evaluated based on the classical theory. It is found that for cantilevered accelerometers with a beam thickness of the order of the material length scale parameter, the classical theory gives a rough estimation of the dynamic response of the system. In this situation, the error of using the classical theory may change the prediction of the system behavior from unstable to stable. [ABSTRACT FROM AUTHOR]

Maintenance of ever-expanding road networks all over the world is a critical task and regular monitoring of the road surface is imperative for successful maintenance. Existing monitoring techniques use dedicated vehicles equipped with sensors. Limited availability of these specialized vehicles makes regular monitoring very challenging. This paper explores a novel approach of empowering the smartphone user community for monitoring roads that they use. Smartphones are used for sensing the road surface conditions from a moving vehicle. The system involves client applications on smartphones that collect accelerations as the users travel on the roads, processing of the information and communication to a central server, georeference database, and visualization of road conditions on Google maps. In this paper, the fuzzy logic--based road surface roughness classification is proposed for monitoring the road roughness. The implementation has been demonstrated in different road networks at northern region of India. The experiment demonstrates the huge potential of user community participation in maintenance of road infrastructure. [ABSTRACT FROM AUTHOR]

A novel micro-electro-mechanical systems (MEMS) inertial microswitch with a flexible contact-enhanced structure to extend the contact duration has been proposed in the present work. In order to investigate the stiffness k of the stationary electrodes, the stationary electrodes with different shapes, thickness h, width b, and length l were designed, analyzed, and simulated using ANSYS software. Both the analytical and the simulated results indicate that the stiffness k increases with thickness h and width b, while decreasing with an increase of length l, and it is related to the shape. The inertial micro-switches with different kinds of stationary electrodes were simulated using ANSYS software and fabricated using surface micromachining technology. The dynamic simulation indicates that the contact time will decrease with the increase of thickness h and width b, but increase with the length l, and it is related to the shape. As a result, the contact time decreases with the stiffness k of the stationary electrode. Furthermore, the simulated results reveal that the stiffness k changes more rapidly with h and l compared to b. However, overlarge dimension of the whole microswitch is contradicted with small footprint area expectation in the structure design. Therefore, it is unreasonable to extend the contact duration by increasing the length l excessively. Thus, the best and most convenient way to prolong the contact time is to reduce the thickness h of the stationary electrode while keeping the plane geometric structure of the inertial micro-switch unchanged. Finally, the fabricated micro-switches with different shapes of stationary electrodes have been evaluated by a standard dropping hammer system. The test maximum contact time under 288 g acceleration can reach 125 µs. It is shown that the test results are in accordance with the simulated results. The conclusions obtained in this work can provide guidance for the future design and fabrication of inertial microswitches. [ABSTRACT FROM AUTHOR]

On 23 October 2011, a Mw = 7.2 earthquake occurred in the Van Province in eastern Turkey, killing 604 people. The earthquake was triggered by a thrust fault due to a compression stress in the region, and caused extensive damage over a large area. Many structures in the earthquake region collapsed, and the damage spread from the city of Van to the town of Erciş, in a distance of 60 km. The earthquake generated several slope movements and liquefaction failures in the region, and this study evaluates these processes from the perspective of engineering geology, and presents field and laboratory results related to these processes. Attenuation relationships were used for estimation of peak ground accelerations (PGAs), and an empirical liquefaction evaluation method employing ground accelerations was used to define threshold accelerations initiating the liquefaction. The results demonstrate that landslides were widespread and more frequently observed in the field in comparison with earthflows and rockfalls. Flow-type liquefaction and lateral spreading was found to be widespread and more common than the liquefaction-related settlement. The minimum threshold acceleration value for the initiation of soil liquefaction was calculated to be 188.87 cm s−2 (~0.19 g) in the earthquake region. Laboratory results indicated that the soil liquefaction was closely associated with grain size. The slope instabilities, liquefaction and associated ground failures occurred mainly in rural areas, and their impact on structures was quite low as compared to the human loss and structural damage by the earthquake.

Although many researchers have begun to study the area of Cyber Physical Social Sensing (CPSS), few are focused on robotic sensors. We successfully utilize robots in CPSS, and propose a sensor trajectory planning method in this paper. Trajectory planning is a fundamental problem in mobile robotics. However, traditional methods are not suited for robotic sensors, because of their low efficiency, instability, and non-smooth-generated paths. This paper adopts an optimizing function to generate several intermediate points and regress these discrete points to a quintic polynomial which can output a smooth trajectory for the robotic sensor. Simulations demonstrate that our approach is robust and efficient, and can be well applied in the CPSS field. [ABSTRACT FROM AUTHOR]

Rapid response is required for many applications of a micro-electro-mechanical system (MEMS) inertial switch device. To achieve a rapid response and have a long contact time, the influence of applied acceleration characteristics on the performance of a proposed MEMS inertial switch, such as response time and contact time, was investigated. The results indicate that the response time of the switch gradually decreases, but the contact time rapidly increases first and then smoothly increases, as the acceleration amplitude increases and the pulse width is a constant. Furthermore, the broadening of acceleration pulse width will result in a sudden increase of response time. For the sake of rapid response, the switch should be used within a limited pulse width range of 0 < t0 < 5.78π/ωn1, as the applied acceleration amplitude is 1.2 times of the acceleration threshold. The fabricated switches were tested by a shock test device. The test results are in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

This paper proposed a theoretical model of seismic rotational stability of gravity retaining wall, using the multi-block upper-bound method. In this model, the cohesionless backfill in the failure zone was meshed into an infinite number of rigid blocks parallel to planar failure surface, in order to establish the energy dissipation equation of the wall-soil system based on the kinematically admissible velocity field. The critical acceleration due to earthquake-induced pseudo-static inertial force was derived through the energy dissipation equation. The model explicitly took account of the height, shape, and unit weight of the retaining wall, the properties of the backfill soil (i.e., unit weight and angle of shearing resistance) and the friction angle of the wall-soil interface. The proposed upper-bound solutions are consistent with those obtained by the limit equilibrium theory by Zeng and Steedman (2000), whereas in this method the vector of earth pressure need not to be assumed. [ABSTRACT FROM AUTHOR]

Zero velocity update (ZUPT) plays an important role in pedestrian navigation algorithms with the premise that the zero velocity interval (ZVI) should be detected accurately and effectively. A novel adaptive ZVI detection algorithm based on a smoothed pseudoWigner-Ville distribution to remove multiple frequencies intelligently (SPWVD-RMFI) is proposed in this paper. The novel algorithm adopts the SPWVD-RMFI method to extract the pedestrian gait frequency and to calculate the optimal ZVI detection threshold in real time by establishing the function relationships between the thresholds and the gait frequency; then, the adaptive adjustment of thresholds with gait frequency is realized and improves the ZVI detection precision. To put it into practice, a ZVI detection experiment is carried out; the result shows that compared with the traditional fixed threshold ZVI detection method, the adaptive ZVI detection algorithm can effectively reduce the false and missed detection rate of ZVI; this indicates that the novel algorithm has high detection precision and good robustness. Furthermore, pedestrian trajectory positioning experiments at different walking speeds are carried out to evaluate the influence of the novel algorithm on positioning precision. The results show that the ZVI detected by the adaptive ZVI detection algorithm for pedestrian trajectory calculation can achieve better performance. [ABSTRACT FROM AUTHOR]

A novel micromachined tunable bistable mechanism is developed and demonstrated on a microelectromechanical systems prototype device. The proposed design, modeling, and characterization of the prototype device, which is electrostatically driven and fabricated by silicon-on-insulator multi-user MEMS processes (SOIMUMPs), are presented. The mechanism comprises noninterdigitated comb drives, which are specially designed to generate a nonlinear electrostatic force that results in adjustable bistability when balanced with a linear mechanical restoring force. The finite element method (FEM) simulation is utilized to analyze the bistability and its tunability. In experimentation, the distance between the two stable states is able to be tuned from 6.5 to 8 \mu \textm by just varying the locking voltage. [2016-0023] [ABSTRACT FROM AUTHOR]

Field observations suggest that preshaken natural sands in some seismic regions have high liquefaction resistance as a result of geologic aging and/or preshaking. This paper focuses on the young silty sand deposits located in the Imperial Valley of California. Recent deposition and intense seismic activity in the Valley suggest that preshaking is the main cause of their increased liquefaction resistance. The first part of the paper examines the liquefiable layer at the Wildlife site, which may have been deposited by flooding approximately between 1905-1907. The site was instrumented with accelerometers and piezometers in 2005, providing data over the last 10 years. The following conclusions are reached from this and from the catalog information on earthquakes before 2005: (1) Since 1907, the Wildlife layer has been subjected to approximately 60-70 earthquakes having αmax ≥ 0.1 g at the site, which caused pore pressure buildup in the layer; (2) most of these earthquakes generated excess pore pressures but generally did not liquefy the soil (Events A); and (3) approximately 10 or 20% of all earthquakes were capable of liquefying the layer immediately after deposition (Events B). This information was used to plan a centrifuge experiment that crudely simulated the history of the Wildlife site. In this test, 66 base shakings were applied to the base of a 6-m prototype homogeneous deposit of loose saturated silty sand, with a ratio of one Event B for every 10 Events A. Events B liquefied the deposit at the beginning but not at the end of the experiment. Events A liquefied the deposit at very shallow depths at the beginning but stopped liquefying it very soon into the experiment. Finally, an Event B caused the next Event A to generate more excess pore pressures, with this effect being canceled rapidly by a couple of subsequent Events A. The lack of liquefaction by Events B after heavy preshaking in the experiment is consistent with theWildlife layer response to the 2010,Mw = 7.2, El Mayor-Cucupah earthquake, an Event B that generated only a 19% pore pressure ratio at the site. [ABSTRACT FROM AUTHOR]