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Highlights: [•] A nickel MEMS inertia switch has been designed and fabricated. [•] The switch was modeled and simulated by finite element ANSYS software. [•] The threshold acceleration and work frequency was analyzed and predicted. [•] The process is easier and the contact time is prolonged effectively. [•] The switch has better unidirectivity and reliability. [Copyright &y& Elsevier]

Since their discovery in 1831, Faraday waves have played a crucial role in the development of novel methodologies for vibration absorption or assembly of microscale materials including soft matter and biological constituents. This work discusses a fundamentally different application of Faraday waves. A new methodology is proposed to harness energy from environmental vibrations via the activation of Faraday waves on the surface of a magnetic fluid. To this end, a proof-of-concept of the proposed harvester is first presented and its performance is experimentally analyzed near the principal parametric resonances of the first and second modes. Subsequently, a mathematical model is constructed to describe the dynamic behavior of the harvester using perturbation techniques. The model is validated against experimental data and light is shed onto the favorable conditions for energy harvesting. [ABSTRACT FROM AUTHOR]

A physical model of a Burgers vortex was created in the laboratory with characteristics corresponding to dissipative‐scale eddies that copepods are likely to encounter in turbulent flows. The swimming behavior of three marine copepod species is assessed as a function of vortex strength in and around the flow structure with the vortex axis aligned vertically or horizontally in the water. The studied species are Acartia tonsa, an estuarine copepod with a hop‐sink swimming style; Temora longicornis, a coastal copepod with a cruise swimming style; and Calanus finmarchicus, an open‐ocean copepod with a cruise‐sink swimming style. The results show that copepods change their swimming behavior with the intensity of the Burgers vortex and reveal species‐specific responses in nearly all kinematic parameters. A. tonsa and C. finmarchicus exhibited the strongest behavioral response to increasing vortex strength and T. longicornis exhibited the weakest response. A. tonsa and T. longicornis showed no response to changes in vortex orientation, whereas the behavior of C. finmarchicus revealed some vortex orientation dependence. One common behavior among the species is that the swimming trajectory shape becomes increasingly curved and spiral around the vortex core with increasing vortex strength, which provides a means of local aggregation and increased encounter rate with food and mates. The results are interpreted in relation to differences in swimming style and setal morphology among the species. [ABSTRACT FROM AUTHOR]

To improve the battery state of charge (SOC) of the electric vehicle (EV), this paper proposes a master–slave electro-hydraulic hybrid electric vehicle (MSEH-HEV). The MSEH-HEV uses a planetary row as the core transmission component to realize the interconversion between mechanical energy, hydraulic energy and electrical energy. Meanwhile, this paper introduces the six working modes in vehicle operation, matches the parameters of key components to the requirements of the vehicle's performance and designs a rule-based control strategy to dominate the energy distribution and the operating mode switching. The research uses AMESim and Simulink to perform a co-simulation of the MSEH-HEV, and the superiority of MSEH-HEV is testified by comparing it with an AMESim licensed EV. The simulation results show that in the Economic Commission for Europe (ECE) and the Extra Urban Driving Cycle (EUDC), the MSEH-HEV has a 15% reduction in battery consumption, and the motor peak torque is greatly reduced. Moreover, a fuzzy control strategy is designed to optimize the rule-based control strategy. Ultimately, the optimized strategy further reduces the motor torque while maintaining the battery SOC. In this paper, the applicable research consists of the necessary references for the design matching of future electro-hydraulic hybrid electricity systems. [ABSTRACT FROM AUTHOR]

Summary: To improve nutrient utilization and pathogenic resistance of plants in space, it is crucial to understand the effects of microgravity on the plant root microbiome. However, the finer details of whether and how microgravity affects the root microbiome remain unclear. Here, we found that simulated microgravity elicits no significant changes in fungal community composition and diversity, whether rhizosphere or endophytic. However, simulated microgravity caused a significant change in the composition and diversity of endophytic bacteria of wheat seedlings, but not in rhizosphere bacteria. The alteration of endophytic bacterial communities demonstrates that wheat seedlings adopt strategies to recruit additional endophytic Enterobacteriaceae and increase the stability of the endophytic bacterial network to respond to the challenge of simulated microgravity. Furthermore, our results also suggest that the corresponding changes in endophytic bacteria under simulated microgravity are closely related to a significant decrease in metabolites of the host's carbon metabolism, flavonoid biosynthesis, benzoxazinoid biosynthesis, and tryptophan metabolism pathways. Our findings reveal details important to our understanding of the impact of gravity on the microbial community of plant seedlings and the theoretical basis for manipulation of microorganisms to ensure efficient plant production in space. [ABSTRACT FROM AUTHOR]

This work couples a magnetic multi-stable mechanism to a pendulum vibration energy harvester so as to widen its bandwidth, especially in low-frequency operation. Multiple stable points are formed by a movable permanent magnet installed on the pendulum and two fixed permanent magnets installed symmetrically on the base of the energy harvester. Thus, the pendulum can swing between the stable points at two sides, which causes large motion amplitude and power generation. In designing the prototype of the energy harvester, dynamical modeling and potential energy analysis are carried out to achieve a low threshold for snap through. An experimental setup is developed and a series of comparative experiments are implemented to investigate prototype performance. It is shown that the energy harvester with the fixed magnets can generate a noticeable normalized induced voltage at 0.7 Hz, while the energy harvester without the fixed magnets requires the excitation frequency of 1.0 Hz to reach a similar level. The electrical outputs varying with vibration acceleration and load resistance are also examined. In general, the experimental results verify the effectiveness of the proposed structure on enlarging frequency bandwidth. This work can provide a promising candidate of energy harvesting for low-frequency applications such as ocean wave. [ABSTRACT FROM AUTHOR]

We consider an extended theory of gravity with Lagrangian ℒ = f (R , T (n)) , with T (n) being a 2 n th-order invariant made of contractions of the energy–momentum tensor. When n = 1 , this theory reduces to f (R , T) gravity, where T accounts for the trace of the energy–momentum tensor. We study the gravitational wave polarization modes, from which it results that when the matter Lagrangian contains dynamical scalar fields minimally coupled to the geometry, further polarization modes arise with respect to General Relativity. Finally, we show that the motion for test particles is nongeodesic and we explicitly obtain the extra force. [ABSTRACT FROM AUTHOR]

This paper presents a single-degree-of-freedom (SDOF) constitutive model for assessing the performance of freestanding block contents of buildings. The model incorporates a bespoke damper to account for energy dissipation associated with rocking. It is advantageous in its direct correlation, via energy conservation, to the restitution coefficient for impact during rocking. A comparative study with the existing SDOF rocking models shows that the proposed model significantly improves the accuracy of free-rocking simulations, in which inherent damping predominantly affects response. It provides a promising and efficient tool for computationally intensive performance evaluation of nonstructural components. [ABSTRACT FROM AUTHOR]

Vehicular Ad-hoc NETworks (VANETs) is an important research domain as it deals with the safety of vehicles moving on roads. The selection of the most prominent routing protocol in this field is a challenging job due to the high mobility rate of VANETs. The foremost motive for writing this paper is to recognize the most suitable protocol that can be used for a high-density traffic region. Therefore, the evaluation of six popular routing protocols (AODV, DSDV, DSR, GPSR, OLSR, and ZRP) of VANETs is examined in the congested city of Delhi. For this, a methodology is being presented that explains the creation of a network using the SUMO tool and assigning a trip and route to the obtained network through the Origin-Destination matrix. Then, by adopting the created network file, the TCL File and NAM File are generated using the NS-2. Finally, selected protocols' performance is examined and evaluated based on the metrics such as Throughput, Packet Delivery Ratio (PDR), Delay, Packet Loss Ratio (PLR), and Routing Overhead. The results showed that the AODV protocol acts as an appropriate routing protocol and could perform better with our presented approach. Also, the comparison is conducted with the results obtained for the AODV routing protocol using the presented approach and the existing approaches. The comparison results depict that the AODV routing protocol presents much better results by using the presented methodology than by using the existing methods in terms of throughput, delay, and PDR. [ABSTRACT FROM AUTHOR]

This paper presents a review of the recent advances on micromachined inertial switches/triggers. The review focuses on their advantages and disadvantages, sensitive directions, mechanisms of contact-enhancement, threshold accuracy, and the tunability of the acceleration threshold. Several applications of these sensors are highlighted including in healthcare, structural health monitoring, internet of things, and military. Recent contemporary research directions are also discussed, such as multi-directions/axis, multi-threshold sensors, and machine learning implementation. The article concludes with discussion on future development trends and performance improvements of inertial switches. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer composites are an excellent choice for bridge decks due to high strength, lightweight, resistance to corrosion, and long-term durability with a 100-year design life. Structural health monitoring is useful for the long-term assessment of the condition of the bridge structure and obtaining a response to complex loads considering environmental conditions. Bridge structures have been studied primarily using distributed fiber optic sensing, such as Brillouin scattering; however, critical events, including damage detection, can be missed due to low spatial resolution. There is also a critical need to conduct a comprehensive study of static and dynamic loading simultaneously for fiber-reinforced composite bridge structures. In this study, a novel approach was implemented using two sensor technologies, optical frequency domain reflectometry and fiber Bragg grating-based sensors, embedded in a glass-fiber-reinforced composite bridge deck to simultaneously monitor the deformation response of the bridge structure. The optical frequency domain reflectometry sensor utilizing Rayleigh scattering provides high spatial strain resolution were positioned strategically based on expected stress distributions to measure strain in the longitudinal, transverse, and diagonal directions along the span of the composite bridge. Furthermore, fiber Bragg grating based sensors are used to monitor the response to dynamic vehicular loading and deformations from an automotive-crash-type event on the bridge structure. To monitor environmental variables such as temperature, a custom wireless configured sensor package was developed for the study and integrated with a composite bridge located in Morgan County, Tennessee. Additionally, a triaxial accelerometer was used to monitor the vehicular dynamic loading of the composite bridge deck in parallel with fiber Bragg grating sensors. When appropriate, mid-point displacements were compared with strain-distribution measurements from the fiber optic sensor-based data. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to propose standard definitions (velocity ranges) that were determined by an objective analysis of time motion data and were used in global positioning system data analysis that was used to measure sprinting in field sport athletes. A discussion of the data analysis methods which were used in the research, and of the information about sprinting which was revealed with the data analysis, is presented.

Abstract: Capital investment in national infrastructure is significant. The need to maintain and protect critical infrastructure links has led in recent years to significant developments in the area of structural health monitoring. The objective is to track a structure’s long-term performance, typically using sensors, and to successively compare the most recently measured responses with prior response history. During construction of the West Street On-Ramp, a curved concrete box girder bridge, located in the city of Anaheim (California), eleven accelerometers were permanently installed on its bridge deck. The associated data acquisition system was configured to record once a specified threshold acceleration response was exceeded; during the period 2002–2010 a total of 1350 datasets including six earthquakes, for each of the eleven sensors, were acquired. This automatically acquired data was supplemented, during the summer of 2009, with responses measured during controlled vehicle tests. Six accelerometers were additionally installed on the frame of the weighed test vehicle. This paper presents the findings of the analyses of these measured data sets and serves to inform owners and managers as to the potential feedback from their instrumentation investment. All response histories were analyzed using frequency domain techniques for system identification. Extraction of the modal characteristics revealed a continuous reduction, of approximately 5%, in the first three natural frequencies over the period of the study. The measured responses from the vehicle sensors are discussed in the context of identifying the potential for bridge frequency measurement using instrumented vehicles. [Copyright &y& Elsevier]

A tristable compliant mechanism is a mechanical device that can hold three distinct positions where the strain energy stored in the flexible members falls in its minima. This unique feature makes them very useful in many applications such as overload protection, threshold acceleration sensing, and shape reconfiguration. For the currently available tristable designs, there is a middle stable position among the three stable positions, and switching between the other two stable positions requires to pass through the middle one. This work presents a novel fully compliant tristable mechanism called non-transit tristable mechanism (NTTM), which can directly switch between every two stable positions without passing through the other one. A kinetostatic model using the chained beam-constraint-model is developed for the proposed mechanism, based on which two NTTMs are successfully identified. The non-transit tristable behaviors of the NTTM designs are verified by the results of nonlinear finite element model and the experimental results of a 3D printed prototype. • A NTTM that can directly switch between every two stable positions is proposed. • A kinetostatic model using CBCM is developed. • NTTMs designs are successfully identified. • Non-transit tristable behaviors are verified by NFEA model and experimental results. [ABSTRACT FROM AUTHOR]

When an oil droplet is placed on a quiescent oil bath, it eventually collapses into the bath due to gravity. The resulting coalescence may be eliminated when the bath is vertically vibrated. The droplet bounces periodically on the bath, and the air layer between the droplet and the bath is replenished at each bounce. This sustained bouncing motion is achieved when the forcing acceleration is higher than a threshold value. When the droplet has a sufficiently low viscosity, it significantly deforms: spherical harmonic Yℓm modes are excited, resulting in resonant effects on the threshold acceleration curve. Indeed, a lower acceleration is needed when ` modes with m = 0 are excited. Modes m ≠ 0 are found to decrease the bouncing ability of the droplet. A break of degeneracy is observed for the m parameter. In particular, when the mode ℓ = 2 and m = 1 is excited, the droplet rolls on the vibrated surface without touching it, leading to a new self-propulsion mode. [ABSTRACT FROM AUTHOR]

Prediction of the rotational displacements, induced by earthquake is a key aspect of the seismic design of retaining walls. In this paper, the pseudodynamic method is used to compute rotational displacements of the retaining wall supporting cohesionless backfill under seismic loading. The proposed method considers time, phase difference, and effect of amplification in shear and primary waves propagating through the backfill and the retaining wall. The influence of ground motion characteristics on rotational displacement of the wall is evaluated. Also the effects of variation of parameters like wall friction angle, soil friction angle, amplification factor, shear wave velocity, primary wave velocity, period of lateral shaking, horizontal, and vertical seismic accelerations on the rotational displacements are studied. Results are provided in graphical form with a comparison to the available pseudostatic result to validate the proposed theory. Present results give higher values of rotational displacements of the wall when compared with the available results by pseudostatic analysis. [ABSTRACT FROM AUTHOR]

Granular material motion in a vibrating bed was investigated using an optical signal analyzing method. When the vessel relative acceleration was greater than some threshold acceleration and the particle was located higher than some threshold height in the bed, the particle vertical vibrating frequency deviated from the vibrator frequency and the particle vibrating frequency was half of the vibrator frequency. When 3.5-mm rubber particles were used, the particle vertical vibrating frequency deviated from the vibrator vibrating frequency when the relative acceleration was greater than 1.75 g and the deviation was observed when there was at least one particle layer below the insert card. The threshold relative acceleration causing the state transition increases with the increase of vibrator frequency. When particles are subjected to vertical vibration, the fluid-like behavior of the particle bed initiated from the surface of the bed with increasing relative acceleration. The interaction of the rising and falling momentum fluxes provides a possible mechanism for the state transition of the granular materials in a vibrating bed. [ABSTRACT FROM AUTHOR]

This paper describes the experimental assessment of lateral sloshing forces developed within scaled road tankers as a function of fill level and container shape, focusing on high fill levels (from 90 to 98 per cent) and three container shapes (oval, modified oval, and circular). The purpose of the study was to estimate the effect of sloshing forces on the lateral stability of tank trucks when operating almost fully loaded. Water was used as the working fluid while the lateral dimensional characteristics of the containers represented a reduction scale of road tankers in the range of 1:5. Containers were subjected to a lateral excitation imparted by a sinusoidal electromagnetic shaker that moved a wheeled container/support assembly at a range of frequencies. The residual after-perturbation sloshing forces were measured by means of a force transducer connected to the shaker ram, and recorded for analysis. For the 98 per cent fill level, normalized sloshing forces were found to represent up to 4 per cent of the total liquid weight. Application of these normalized forces to actual size tank trucks further suggests that the rollover threshold acceleration of a rigidly suspended tank truck, due to sloshing, can be reduced by 2 per cent for the 98 per cent fill level, and around 10 per cent for the 90 per cent fill level. These already significant reductions in the roll stability of tank trucks would be more severe for a spring suspended vehicle, thus rationalizing the rollover trend of such vehicles. The use of longitudinal sloshing suppressors is strongly recommended. [ABSTRACT FROM AUTHOR]

This study aimed to examine physiological, mechanical and perceptual loading in small-sided games using different relative playing areas with balanced and unbalanced player numbers. Data were collected in twelve elite youth male soccer players and included heart rate and standard time-motion outputs using commercial GPS. The data demonstrated higher cardiovascular, physical and perceptual demands with increasing pitch size (e.g. average HR was 88.7 vs. 86.7% HRmax with 8 vs. 2 high-intensity acceleration in medium vs. small pitch formats. The largest pitch format resulted in a greater accumulation of high-intensity distance (47 ± 30 m), higher peak velocity (25.2 ± 1.6 km.h−1) and a higher distance and frequency of accelerations (35 ± 9 m and 8 ± 3) compared with the smallest pitch (all p < 0.01). In unbalanced games, there was significantly greater average heart rate in the overloaded team (84.4 ± 4.9 vs. 80.4 ± 4.8% HRmax in 4 v. 6). These data suggest that different game formats including numerical imbalance could be prescribed for squad management to target conditioning stimuli for specific players (e.g. to target a higher training load for players that do not get consistent match exposure). [ABSTRACT FROM AUTHOR]

We describe source and path attributes of the Next Generation of Ground-Motion Attenuation for Subduction zones (NGA-Sub) project relational database. The database contains 991 earthquakes between 1937 and 2016 that meet quality assurance standards and have assigned event types (mostly interface or intraslab). Data curation emphasized large magnitudes: 73% of events have M > 5 and 13 events have M > 8. Event attributes in the database can be broadly divided into those related to the moment tensor, those related to rupture surface geometry (referred to as finite-fault parameters), and categorizations by type (e.g. interface, intraslab) and sequence classification (mainshock, aftershock). Earthquake information and moment tensor parameters compiled from earthquake catalogs include event date and origin time, hypocenter location, seismic moment, and the strike, dip, and rake angles of nodal planes. Finite-fault parameters include along-strike length, down-dip width, and depth to top-of-rupture for one or more rectangles used to parameterize rupture surface geometry. These are modified from models in literature where available, and otherwise are simulated using procedures customized for subduction earthquakes. Rupture distance and other metrics are computed using finite-fault representations of sources, and (as applicable) are partitioned into forearc and backarc components. Forearc and backarc regions are defined based on volcano locations, and are assigned to events and sites. [ABSTRACT FROM AUTHOR]

Due to the mechanical nature of container handling operations, as well as natural factors, container and handling infrastructure suffers various types of damage during use, especially within the tight and enclosed environments of a ship's hull. In this operational environment, it is critical to detect any sort of physical impacts between the vertical cell guides of the ship's hull and the container. Currently, an inspection of impacts and evaluation of any consequences is performed manually, via visual inspection processes. This process is time-consuming and relies on the technical expertise of the personnel involved. In this paper, we propose a five-step impact-detection methodology (IDM), intended to detect only the most significant impact events based on acceleration data. We conducted real measurements in a container terminal using a sensory device placed on the spreader of the quay crane. The proposed solution identified an average of 12.8 container impacts with the vertical cell guides during common handling operations. In addition, the results indicate that the presented IDM can be used to recognize repeated impacts in the same space of each bay of the ship, and can be used as a decision support tool for predictive maintenance systems. [ABSTRACT FROM AUTHOR]

To better understand the behavior of the American lobster (Homarus americanus) in the wild, we developed the C-HAT (Crustacean Heart and Activity Tracker): a datalogger capable of continuously recording the triaxial acceleration, compass heading, and heart rate of lobsters that are freely moving in their natural habitat. C-HATs and acoustic transmitters were affixed to six lobsters that were released within an acoustic positioning array off the coast of New Hampshire (USA) and recaptured by divers after 15–47 h at large. Lobster heart rates tended to be ~ 60 beats per minute (bpm) at rest, but increased to ~ 80 bpm during periods of activity. The presence of brief cardiac startle responses during the beginning of some periods of activity suggested that at least a third of their movement bouts occurred in response to external stimuli, such as interactions with other species. The combination of acoustic positioning data and datalogging allowed us to determine if various indices of acceleration could be used to estimate distance traveled. We found a significant correlation between a Movement Index (MI), based on differentiation of the three axes of acceleration, and the distance lobsters traveled in 10 min based on telemetry data. This enabled us to use the MI in concert with compass headings to reconstruct lobster movement paths via dead reckoning. This study demonstrates the potential for low-cost, open-source, dataloggers to provide detailed information on the daily behavior and physiology of marine invertebrates in the wild. [ABSTRACT FROM AUTHOR]

Label‐free detection methods such as resistive pulse sensing (RPS) have become a pivotal platform for the characterizations of nanoscale objects, providing real‐time monitoring and single‐molecule resolution. Major challenges for RPS platforms include the short translocation time of nanoscale objects passing through the pore and limited dynamic range due to the need for particle sizes to be within 10−90% of the pore size. These issues severely limit the fidelity of the measured signals, particularly when measuring unknown samples. Herein, a T‐junction‐shaped dual pore system that slows down the motion of translocating nanoparticles is proposed, and that allows particle translocations to be unambiguously allocated to one of the two pore structures. Moreover, because the two pore structures are of different sizes, the size range of particles that may be measured without clogging is increased. The prepared dual pores afford to measure the size features and surface charge properties of nanoparticles with high accuracy. Importantly, the dual‐pore system enables the study of the dynamic motion behaviors of adjacent nanoparticles. The application of these dual pores for characterizing the protein corona of bioparticles is exemplified. [ABSTRACT FROM AUTHOR]

Various multimegawatt capacity offshore wind turbines (OWTs) are constructed globally to fulfill increasing energy demand. Many of these structures have already been and will continue to be constructed in seismically active areas. Hence, these structures are at probable risk of an earthquake. The dynamic behavior of monopile-supported various multimegawatt OWTs in liquefiable sand deposit under combined action of operational and seismic loads are investigated in this study. A three-dimensional beam on a nonlinear Winkler foundation model is developed in OpenSees. The monopile and the tower are modeled as a linear Euler–Bernoulli beam. The lateral and vertical pile–soil interfacing behavior is modeled by using p-y, t-z, and q-z spring elements. The strong ground motion is utilized as free-field displacement at spring supports. The effect of the vertical component of seismic motion on the performance of the OWT structure in liquefied soil is examined. [ABSTRACT FROM AUTHOR]

STUDY DESIGN.: A newly developed biofidelic whole cervical spine (WCS) model with muscle force replication (MFR) was subjected to whiplash simulations of varying intensity, and the resulting injuries were evaluated through changes in the intervertebral flexibility. OBJECTIVES.: To identify the soft tissue injury threshold based on the peak T1 horizontal acceleration and the association between acceleration magnitude and injury severity resulting from simulated whiplash using the WCS + MFR model. SUMMARY OF BACKGROUND DATA.: Whiplash has been simulated using mathematical models, whole cadavers, volunteers, and WCSs. The measurement of injury (difference between prewhiplash and postwhiplash flexibilities) is possible only using the WCS model. METHODS.: Six WCS + MFR specimens (C0'''T1) were incrementally rear-impacted at nominal T1 horizontal maximum accelerations of 3.5, 5, 6.5, and 8 g, and the changes in the intervertebral flexibility parameters of neutral zone and range of motion were determined. The injury threshold acceleration was the lowest T1 horizontal peak acceleration that caused a significant increase in the intervertebral flexibility. RESULTS.: The first significant increase (P <0.01) of 39.8% occurred in the C5'''C6 extension neutral zone following the 5 g acceleration. At higher accelerations, the injuries spread among the surrounding levels (C4'''C5 to C7'''T1). CONCLUSIONS.: A rear-end collision is most likely to injure the lower cervical spine by intervertebral hyperextension at a peak T1 horizontal acceleration of 5 g and above. These results may aid in the design of injury prevention systems and more precise diagnoses of whiplash injuries. [ABSTRACT FROM AUTHOR]

Some accelerograms are affected by non-standard recording and digitization problems that mean they are often not used in strong-motion studies. These non-standard problems cannot be corrected by the standard processing techniques that remove low and high-frequency noise from the time-history. Records from analogue instruments are more prone to these problems but even records from digital instruments, which are becoming increasingly common, can be affected by such errors. Since all strong-motion data is valuable it is important to know whether any useful information can be obtained from accelerograms that are affected by such problems. This article examines whether strong-motion records from analogue instruments that are missing their initial part due to late triggering of the instrument and also strong-motion records from digital instruments with low A/D converter resolution can be used for response spectral studies. It is found, by simulating such errors on high-quality strong-motion records, that good response spectral ordinates can be obtained from such `poor-quality' records within the period range of most engineering interest. [ABSTRACT FROM AUTHOR]

Irradiation-induced crystallization of an amorphous phase was stimulated at a Pd-Si amorphous/silicon oxide (a(Pd-Si)/SiOx) interface at 298K by electron irradiation at acceleration voltages ranging between 25 kV and 200 kV. Under irradiation, a Pd-Si amorphous phase was initially formed at the crystalline face-centered cubic palladium/silicon oxide (Pd/SiOx) interface, followed by the formation of a Pd2Si intermetallic compound through irradiation-induced crystallization. The irradiation-induced crystallization can be considered to be stimulated not by defect introduction through the electron knock-on effects and electron-beam heating, but by the electronic excitation mechanism. The observed irradiation-induced structural change at the a(Pd-Si)/SiOx and Pd/SiOx interfaces indicates multiple structural modifications at the metal/silicon oxide interfaces through electronic excitation induced by the electron-beam processes. [ABSTRACT FROM AUTHOR]

In order to solve the problem that the low-g omnidirectional MEMS inertial switches cannot recognize the load direction, a nickel omnidirectional MEMS inertial switch with identifiable load direction and uniform in-plane threshold distribution was designed. The switch is mainly composed of a spring–mass system, four independent flexible radial electrodes and an axial electrode. The function of identifying the direction of acceleration is realized by detecting the closed states of different electrodes. According to the design results of MEMS inertial switch, the dynamic performance of the switch was analyzed by ANSYS software. The results show that the designed switch meets the functional requirements of load direction identification. Based on UV-LIGA multilayer photolithography, the nickel MEMS inertial switch was fabricated on a steel substrate. In the process of fabrication, the line width compensation method was used to reduce the dimensional error caused by swelling phenomenon and removal process of the photoresist. What's more, the thickness compensation method was used to reduce the process error caused by flattening treatment. The overall dimension of the switch is 5300 × 5300 × 270 μm and the smallest line-width is 20 μm. Ultimately, the fabricated switch was tested by the centrifuge device and dropping hammer in XOY plane and Z-axis direction. The dynamic threshold of the switch is between 7.9 and 11.3 g, and the response time in each direction is less than 2 ms. The switch can recognize the direction of acceleration in XOY plane and Z-axis. The switch has an excellent anti-overload performance. [Display omitted] • A low-g MEMS inertial switch with identifiable load direction was designed. • The function was realized by detecting the closed states of different electrodes. • The switch achieves uniform threshold acceleration in each sensitive direction. • The line width compensation method was proposed to improve fabrication accuracy. • The switch was verified with the centrifugal device and the dropping hammer system. [ABSTRACT FROM AUTHOR]

Public transports like the bus and subway inherently experience noise, vibration, and temperature variations that are different from building environment. Each of them can influence passengers' comfort, but little is known about their combined effects, especially how they affect thermal comfort. This paper presents experimental results from a series of human subject tests under different noises, vibrations, and temperatures. 32 subjects' subjective perception and physiological response were collected under three temperatures (22.5, 25.5, 28.5℃), five noise levels (55, 60, 65, 70, 75 dB(A)), and five vibrating accelerations (0, 0.2, 0.4, 0.6, 0.8 m/s2). We also varied the noise and vibration spectrums to simulate the bus and subway environments. In total, 48 195‐min and 192 115‐min laboratory tests were conducted. By using significance tests (paired t tests and two‐way ANOVA tests) and sensitivity analysis (Treed Gaussian Process), the results show that temperature, noise, and vibration exposures can significantly affect subjects' overall satisfaction. More interestingly, high noise and vibration levels can cause warmer thermal sensations. A change in the noise of 20 dB(A) or vibration of 0.6 m/s2 is equivalent to an ambient temperature change of 0.6 °C. We also observed higher heart rates and metabolic heat production at higher levels of noise and vibrating accelerators. Based on the test results, regression models were developed to describe the combined effects of temperature, noise, and vibration on subjects' overall comfort perception and thermal neutral temperature. They can serve as references for the design and operation of public transport environments. [ABSTRACT FROM AUTHOR]

Landslides can cause extensive damage, particularly those triggered by earthquakes. The current study used back propagation of an artificial neural network (ANN) to conduct risk studies on landslides in the area affected by the Manjil-Rudbar earthquake in Iran in 1990 (M = 7.7). Newmark displacement analysis was used to develop an earthquake-induced landslide hazard map for the blocks representing Chahar-Mahal and Chalkasar near the earthquake epicenter, an area of 309 km2. The input data included soil cohesion, soil friction angle, unit weight of soil, unit weight of water, distance from hypocenter, slope, and earthquake magnitude as effective parameters for landslide occurrence. The hazard map was compared with an inventory map and other research findings. The results indicated that the landslides predicted by ANN covered 50% of the inventory map of the study area (2088 of 4097 slide cells). The results of the current study suggest that the ANN method is relatively efficient for accurate prediction of landslides. [ABSTRACT FROM AUTHOR]

Step-based metrics provide simple measures of ambulatory activity, yet device software either includes undisclosed proprietary step detection algorithms or simply does not compute step-based metrics. We aimed to develop and validate a simple algorithm to accurately detect steps across various ambulatory and nonambulatory activities. Seventy-five adults (21-39 years) completed seven simulated activities of daily living (e.g., sitting, vacuuming, folding laundry) and an incremental treadmill protocol from 0.22 to 2.2 m/s. Directly observed steps were hand-tallied. Participants wore GENEActiv and ActiGraph accelerometers, one of each on their waist and on their nondominant wrist. Raw acceleration (g) signals from the anterior--posterior, medial--lateral, vertical, and vector magnitude directions were assessed separately for each device. Signals were demeaned across all activities and band-pass filtered (0.25, 2.5 Hz). Steps were detected via peak picking, with optimal thresholds (i.e., minimized absolute error from accumulated hand counted) determined by iterating minimum acceleration values to detect steps. Step counts were converted into cadence (steps/minute), and k-fold cross-validation quantified error (root mean squared error [RMSE]). We report optimal thresholds for use of either device on the waist (threshold = 0.0267g) and wrist (threshold = 0.0359g) using the vector magnitude signal. These thresholds yielded low error for the waist (RMSE < 173 steps, ≤2.28 steps/min) and wrist (RMSE < 481 steps, ≤6.47 steps/min) across all activities, and outperformed ActiLife's proprietary algorithm (RMSE = 1,312 and 2,913 steps, 17.29 and 38.06 steps/min for the waist and wrist, respectively). The thresholds reported herein provide a simple, transparent framework for step detection using accelerometers during treadmill ambulation and activities of daily living for waist- and wris-worn locations. [ABSTRACT FROM AUTHOR]

We present the results of investigations of planar domain patterns (isolated domains and domain gratings) fabricated by irradiation of the nonpolar Y-surface of LiNbO3 crystals by an electron beam (EB) incident normally onto the surface. The EB recorded domains were investigated using atomic force microscopy, confocal second harmonic generation microscopy, and chemical etching as an auxiliary method. The dependence of the domain characteristics on irradiation conditions (acceleration voltage U, EB current I, and irradiation time tirr) were determined. The length Ld of both isolated domains and domain gratings along the polar axis Z grows linearly with tirr (at U, I=const) with no tending to saturation. The plots Ld(tirr) obtained for U=10 and 15 kV are practically identical, whereas the values of Ld for U=5 kV are essentially lower. The domain thickness Td along the Y-direction, i.e., the depth of the switched layer grows with acceleration voltage U. These results are discussed in terms of space-charge fields formation arising under EB irradiation of insulators. The linearity of Ld(tirr) is accounted for by the frontal domain growth via the viscous friction law. The experimental dependence of Td on U supports the suggestion that the domain thickness is determined by the penetration depth Re of primary electrons, which in turn is governed by U. The difference in Ld(tirr) plots for different U is accounted for by different electron emission σ. Indirect evidences of a defect structure modification in a thin surface layer with respect to the crystal bulk are obtained. [ABSTRACT FROM AUTHOR]

A three dimensional distinct element model was developed for the multiblock Baalbek columns to investigate the response of the existing columns as well as 0.5m and 1m scaled models used in shaking table experiments. Periodic pulses of varying shapes, periods, and accelerations were applied and the critical combinations of acceleration and period that caused collapse were noted. The response and mode of collapse are shown to be dependent on the period and the amplitude of the pulse. Depending on the size of the column and the period of the applied critical pulse three modes of collapse are observed: (1) multiblock rocking/wobbling followed by toppling of one or more blocks; (2) rock and/or wobble then overturn along or outside the applied pulse plane; (3) overturn after one or two impacts along the plane of the applied pulse. The displacement history of the column was plotted alongside the ground motion to visualize and quantify the rocking and /or wobbling. All column sizes showed the same response qualitatively in the acceleration-period space and the wobbling was shown to be confined to a well-defined region. Stability charts delineating the safe-unsafe boundaries showed bi-modal behavior for all pulses tested but with a shift due to the different pulse energy contents. Numerical results compared well with experimental data from shaking table experiments on the scaled columns. The capabilities of the three dimensional numerical modeling approach are confirmed in this work for use as a predictive tool or an archaeoseismic analysis tool for columns and large masonry structures. [ABSTRACT FROM AUTHOR]

Small and micro-scale energy harvesting is an essential and viable option for the powering of portable and maintenance free electronic devices, wireless sensor nodes, and similar applications. In this regard, piezoelectric harvesters have presented promising outcomes. This article provides a sequential, comprehensive, and informative survey of potential well based models and studies related to piezoelectric harvesters (PEH). Piezoelectric materials used for energy harvesting are discussed briefly, following which a non-dimensional generalized model is derived to set the discussion on a common platform. Dynamics of various potential well configurations are presented using the generalized model before discussing specific models and related studies. The survey is classified into symmetric and asymmetric potential well categories. Under the symmetric head, lumped and distributed parameter linear models and tuning methods for improving the broadband response are discussed. Subsequently, studies related to nonlinear mono-stable, bi-stable, and tri-stable potentials showing interwell, multi-periodic and chaotic oscillations with improved broadband response are discussed. The asymmetric section studies the influence of asymmetries on the performance of the mono-stable, bi-stable, and tri-stable configurations. Few other configurations outside the cantilever type PEH were mentioned, realizing the widespread research in this field. Important observations and future challenges for performance improvement are also discussed. [ABSTRACT FROM AUTHOR]

The energetics of drop deposition are considered in the capillary-ballistic regime characterized by high Reynolds number and moderate Weber number. Experiments are performed impacting water/glycol drops onto substrates with varying wettability and contact-angle hysteresis. The impacting event is decomposed into three regimes: (i) pre-impact, (ii) inertial spreading and (iii) post contact-line (CL) pinning, conveniently framed using the theory of Dussan & Davis (J. Fluid Mech., vol. 173, 1986, pp. 115–130). During fast-time-scale inertial spreading, the only form of dissipation is CL dissipation ($\mathcal {D}_{CL}$). High-speed imaging is used to resolve the stick-slip dynamics of the CL with $\mathcal {D}_{CL}$ measured directly from experiment using the $\Delta \alpha$ - $R$ cyclic diagram of Xia & Steen (J. Fluid Mech., vol. 841, 2018, pp. 767–783), representing the contact-angle deviation against the CL radius. Energy loss occurs on slip legs, and this observation is used to derive a closed-form expression for the kinetic K and interfacial $\mathcal{A}$ post-pinning energy $\{K+\mathcal {A}\}_p/\mathcal {A}_o$ independent of viscosity, only depending on the rest angle $\alpha _p$ , equilibrium angle $\bar {\alpha }$ and hysteresis $\Delta \alpha$ , which agrees well with experimental observation over a large range of parameters, and can be used to evaluate contact-line dissipation during inertial spreading. The post-pinning energy is found to be independent of the pre-impact energy, and it is broken into modal components with corresponding energy partitioning approximately constant for low-hysteresis surfaces with fixed pinning angle $\alpha _p$. During slow-time-scale post-pinning, the liquid/gas ($lg$) interface is found to vibrate with the frequencies and mode shapes predicted by Bostwick & Steen (J. Fluid Mech., vol. 760, 2014, pp. 5–38), irrespective of the pre-impact energy. Resonant mode decay rates are determined experimentally from fast Fourier transforms of the interface dynamics. [ABSTRACT FROM AUTHOR]

Pathological proteins contributing to Alzheimer's disease (AD) are known to disrupt normal neuronal functions in the brain, leading to unbalanced neuronal excitatory-inhibitory tone, distorted neuronal synchrony, and network oscillations. However, it has been proposed that abnormalities in neuronal activity directly contribute to the pathogenesis of the disease, and in fact it has been demonstrated that induction of synchronized 40 Hz gamma oscillation of neuronal networks by sensory stimulation reverses AD-related pathological markers in transgenic mice carrying AD-related human pathological genes. Based on these findings, the current study evaluated whether non-invasive sensory stimulation inducing cortical 40 Hz gamma oscillation is clinically beneficial for AD patients. Patients with mild to moderate AD (n = 22) were randomized to active treatment group (n = 14; gamma sensory stimulation therapy) or to sham group (n = 8). Participants in the active treatment group received precisely timed, 40 Hz visual and auditory stimulations during eye-closed condition to induce cortical 40 Hz steady-state oscillations in 1-h daily sessions over a 6-month period. Participants in the sham group were exposed to similar sensory stimulation designed to not evoke cortical 40 Hz steady-state oscillations that are observed in the active treatment patients. During the trial, nighttime activities of the patients were monitored with continuous actigraphy recordings, and their functional abilities were measured by Alzheimer's Disease Cooperative Study – Activities of Daily Living (ADCS-ADL) scale. Results of this study demonstrated that 1-h daily therapy was well tolerated throughout the 6-month treatment period by all subjects. Patients receiving gamma sensory stimulation showed significantly reduced nighttime active periods, in contrast, to deterioration in sleep quality in sham group patients. Patients in the sham group also showed the expected, significant decline in ADCS-ADL scores, whereas patients in the gamma sensory stimulation group fully maintained their functional abilities over the 6-month period. These findings confirm the safe application of 40 Hz sensory stimulation in AD patients and demonstrate a high adherence to daily treatment. Furthermore, this is the first time that beneficial clinical effects of the therapy are reported, justifying expanded and longer trials to explore additional clinical benefits and disease-modifying properties of gamma sensory stimulation therapy. Clinical Trial Registration: clinicaltrials.gov, identifier: NCT03556280. [ABSTRACT FROM AUTHOR]

Landslide susceptibility (LSI) modeling of Darjeeling–Sikkim Himalaya is performed by integrating 28 causative factors on 28C28 combinations on Geographical Information System (GIS) following analytic hierarchy process (AHP)-based multicriteria decision protocol, logistic regression (LR)-based multivariate technique, machine learning data-driven random forest (RF) and artificial neural network (ANN) methods wherein the terrain is classified into 'None' (with: 0.0 < LSI ≤ 0.17), 'Low' (with: 0.17 < LSI ≤ 0.34), 'Moderate' (with: 0.34 < LSI ≤ 0.51), 'High' (with: 0.51 < LSI ≤ 0.68),'Very High' (with: 0.68 < LSI ≤ 0.85) and 'Severe' (with: 0.85 < LSI ≤ 1.00) susceptible zones as validated through standard statistical accuracy tests and direct cross-correlation analysis of all the susceptible zonation maps generated by drawing comparison with the 30% landslide inventory test data. The best integrated thematic RF-based LSI vector layer with an accuracy level of 0.871, in turn, on integration with the vulnerability components like population density, number of households, building types, building height and building density has demarketed approximately 21% of the region under 'Very High' to 'Severe' socioeconomic risk zone while about 36% area are classified under 'Very High' to 'Severe' structural risk zone as implicated by devastating landslide hazards in the region. Ground Penetrating Radar Survey has been conducted on all the slopes in the 'Very High to Severe' landslide susceptible zones wherein near-surface lithologic setting, presence of paleo-slopes and microstructural features like fractures/faults and poorly stratified debris flow have been imaged that provided favorable subsurface conditions for slope failure. Finite element method-based slope failure analysis for Newmark displacement estimates factor of safety (FoS) value that acts as the proxy in defining the degree of slope instability is seen to vary between 1.905 and 2.357 in the 'Low to Moderate' landslide susceptible zone while it ranges between 1.051 and 1.652 in the 'High' landslide susceptible zone and between 0.649 and 1.349 in the 'Very High to Severe' landslide inventory subset along the slopes under both gravity loading and seismic shaking in the terrain. The slope stability analysis puts the yield acceleration between 0.0012 and 0.11984 m/s2 and the total deformation between 0.0027 and 1.4484 m. All these parameters in the classified landslide susceptible zones in unison demonstrate how unstable are the terrain slopes in the 'High to Severe' landslide susceptible zones. [ABSTRACT FROM AUTHOR]

Acoustic and vibrational sensitivity of single identified auditory receptors in bushcrickets was studied by electrophysiological methods. In the intermediate organ, some neurons were identified whose response to acceleration did not depend on the stimulus frequency over a significant frequency range; along with them, there were cells showing increased sensitivity to frequencies of 0.4–0.8 kHz for displacement, and/or 0.1–0.3, 1–1.2, and 1.4–3 kHz for all the vibration parameters. In addition, most of the studied receptors had a zone of increased sensitivity to highfrequency vibrations at 1.5–2.5 kHz. In the sensilla of the crista acustica, increased sensitivity was recorded at frequencies of 0.1–0.3, 0.4–0.8, 1–1.2, and 1.4–2.5 kHz. The best frequencies of a single sensillum may lie in different frequency ranges for different vibration parameters. Such differences in sensitivity to vibration acceleration, vibration velocity, and displacement, and also the different best frequencies in the receptors of the intermediate organ and the crista acustica were probably determined by differences in size, position, and morphological details of the sensilla, their own resonances, and reactions to resonance vibrations of the trachea section bearing the vibroreceptors. Thus, the chordotonal sensillum is a bifunctional mechanoreceptor which, along with auditory sensitivity, can combine the functions of both a displacement receiver and an accelerometer due to the different mechanical properties of its cells and the surrounding structures. [ABSTRACT FROM AUTHOR]

Since the end of the last century, energy harvesting technologies have obtained prominent development as the sustainable power supplies for billions of wireless sensor nodes distributed in both the city and remote areas. Microelectromechanical system (MEMS) energy harvesters based on the energy transferring mechanisms of electrostatic effect, electromagnetic induction, and piezoelectric effect were first proposed to scavenge the vibrational energy from the ambient environment. Thereafter, the piezoelectric nanogenerator and triboelectric nanogenerator emerged as promising techniques to harvest diversified mechanical energy for addressing the energy consumption of flourishing wearable devices. Targeting for a more efficient system, multiple strategies for improving the output performance of individual energy harvesters as well as hybridized energy harvesters are extensively investigated. Merging the well-developed energy harvesters with energy storage, wireless data transmission, and other functional units, self-sustainable systems have been realized. Shortly, with the evolving AI technologies, we can foresee that the AI-assisted self-sustainable systems will also be achieved and play a vital role in the future 5 G era. In this review, we systematically introduce the evolution of energy harvesting techniques in the 5 G and IoT era, with detailed operation principles, structural designs, enhancement strategies, self-sustainable and AI-assisted system development, and our perspectives. [ABSTRACT FROM AUTHOR]