Motion Energy Research Articles

Washable All-in-One Self-Charging Power Unit Based on a Triboelectric Nanogenerator and Supercapacitor for Smart Textiles.

Lightweight, portability, and sustainability have become key factors of the power source for the rapid development of multifunctional wearable electronic devices. In this work, a washable, wearable, and durable self-charging system for human motion energy harvesting and storage based on asymmetric supercapacitors (ASCs) and triboelectric nanogenerators (TENGs) is investigated. The all-solid-state flexible ASC is composed of a cobalt-nickel layered double hydroxide grown on a carbon cloth (CoNi-LDH@CC) as the positive electrode and activated carbon cloth (ACC) as the negative electrode and exhibits the performance of small size, high flexibility, and superior stability. The device was able to provide a capacity of 345 mF cm-2 and a cycle retention rate of 83% after 5000 cycles, which shows great potential as an energy storage unit. Additionally, flexible silicon rubber-coated carbon cloth (CC) is waterproof and soft and can be used as a TENG textile to gain energy for stable charging of an ASC, which presents an open-circuit voltage and short-circuit current of 280 V and 4 μA, respectively. The ASC and TENG can be assembled to continuously collect and store energy, which provides an all-in-one self-charging system qualified with washable and durable for potential applications in wearable electronics.

Moving Together: Social Motor Synchrony in Autistic Peer Partners Depends on Partner and Activity Type

Some suggest autistic people display impaired Interpersonal Synchrony. However, partners of different neurotypes can struggle to connect and empathise with one another. We used Motion Energy Analysis to examine Social Motor Synchrony (SMS) in familiar partners of the same neurotype: pairs of autistic and of neurotypical children. Partners played two shared tablet activities, one to support collaboration by facilitating engagement and other-awareness (Connect), and one with no additional design features to facilitate collaboration (Colours). The neurotypical group showed similar SMS to the autistic group in Colours but lower SMS in Connect. The autistic group displayed similar levels of SMS in each activity. Autistic children can synchronise to a similar, or greater, degree than neurotypical children when the social context and type of task are considered.

Study on the influence of high and low temperature environment on the energy consumption of battery electric vehicles

In order to study the influence of high and low temperature environments on the energy consumption of battery electric vehicles, this paper takes Tianjin as an example to collect the actual road data of 8 battery electric passenger cars for eight months. It determines the correlation between each characteristic parameter and energy consumption based on the maximum mutual information coefficient of short stroke segments, of which the average driving speed correlation is the highest, which is 0.785. Given the two factors that have a greater impact on energy consumption in high and low temperature environments: driving resistance and air conditioning on motion and idle energy consumption analysis, the study shows that in terms of driving resistance, high temperature and low temperature energy consumption are reduced and increased by 5.4% and 13.3% respectively relative to normal temperature; The energy consumption of high temperature and low temperature air conditioner switching on increased by 17.12% and 47.48% respectively compared with the air conditioner off.

Influence of tall buildings on city-scale seismic response analysis: A case study of Shanghai CBD

Tall buildings can affect the seismic safety of shorter buildings in their vicinities. Majority of the studies have investigated such influences by analyzing the structure-soil-structure interactions in the local vicinity. Considering the large mass and long fundamental period of tall buildings, perturbations during earthquakes can affect a very broad area. Therefore, it is important to investigate the influence of tall buildings from a city-scale perspective. Using the Shanghai Central Business District (CBD) area as an example, this study quantified the influence of tall buildings on the seismic responses of sites and buildings using a nonlinear time history analysis. Different earthquake intensities and building configurations were analyzed, and the effects of tall buildings on the ground motion energies, building responses, and damage states were investigated. These findings indicate the need to consider the seismic safety of shorter buildings surrounded by taller ones.

Electric field modulation effect and mechanism on n-alkanes fuel pyrolysis: A ReaxFF MD and DFT study

To promote the fuel utilization efficiency in the aviation and space transport, the electric field was selected as an efficiency method to modify the fuel pyrolysis rate. This work investigated the surrogate fuel component n-alkane (n-pentane, n-heptane and n-decane) pyrolysis process under the electric field. The three n-alkanes pyrolysis rate and reaction pathway were analyzed. And the reaction mechanism under the electric field was discussed by the bond cracking potential energy (PES), system thermal motion and energy. The molecular dynamics results showed the n-alkanes pyrolysis was modulated by the electric field strength, which promotion in weak electric field and inhibition in strong field. The species transformation net was complicated and selective while the conversion flux was reduced by the strong field. The field improved the molecule polarization and deformation to result in the edged carbon bond and H bond dissociation with lower energy barriers. Analyzing the molecular motion and system energy, the intermolecular distance was elongated, and interaction energy was reduced, which caused to the decrease of collision frequency under the field. The contribution of electric field to the single molecule decomposition and inhibition molecules motion worked together on the global n-alkane pyrolysis. This work supplied a theory support to the promoting fuel utilization using the electric energy.

Theoretical modeling of seafloor spatial earthquake ground motion with random fluctuation sea surface

With the growing number of offshore structures, the damage degree and probability of offshore structures under earthquake increases. However, the influence of the fluctuating seawater layer on the propagation of seafloor ground motion is generally ignored in seismic design of offshore structures or ocean ground motion researching. Numerous studies have revealed that the spatial earthquake ground motion on the seafloor is notably affected by the saturation in the soil and the seawater layer overlaying the seabed. A new seawater transfer function to estimate the effect of random fluctuations in the sea surface on the behavior of ground motion was proposed in this paper. The seawater transfer function was derived by incorporating the reflection coefficient of the seawater layer and the scattering coefficient corresponding to the random fluctuation of the sea surface. The reflection of the P wave in the seawater layer between the lower medium and upper medium was considered by a reflection coefficient. The scattering coefficient was utilized to facilitate the estimation of the P wave attenuation due to random sea surface fluctuations. Moreover, the effects of the soil layer and soil saturation under the sea on ground motion are also considered. Taking the above factors into consideration, the ground motions affected by random fluctuations in the sea surface can be synthesized. A water layer transfer function proposed by Crouse and Quilter is used to validate the proposed seawater transfer function. To demonstrate the effect of the new seawater transfer function on ground motion, three example cases are presented. Comparisons among these three case results show that the new seawater transfer function exhibits attenuation at relatively high frequencies. Furthermore, the higher a sea wave is, the more severe the attenuation in the seawater transfer function is. The results also suggest that ground motion energy can be greatly influenced by random fluctuations in the sea surface. Lastly, the simulation method presented in this paper, which considers the fluctuating sea surface, offers a valuable reference for the study of ocean ground motion and presents a more rational approach to seismic simulations for offshore structure research.

Human Behavior Recognition via Hierarchical Patches Descriptor and Approximate Locality-Constrained Linear Coding.

Human behavior recognition technology is widely adopted in intelligent surveillance, human-machine interaction, video retrieval, and ambient intelligence applications. To achieve efficient and accurate human behavior recognition, a unique approach based on the hierarchical patches descriptor (HPD) and approximate locality-constrained linear coding (ALLC) algorithm is proposed. The HPD is a detailed local feature description, and ALLC is a fast coding method, which makes it more computationally efficient than some competitive feature-coding methods. Firstly, energy image species were calculated to describe human behavior in a global manner. Secondly, an HPD was constructed to describe human behaviors in detail through the spatial pyramid matching method. Finally, ALLC was employed to encode the patches of each level, and a feature coding with good structural characteristics and local sparsity smoothness was obtained for recognition. The recognition experimental results on both Weizmann and DHA datasets demonstrated that the accuracy of five energy image species combined with HPD and ALLC was relatively high, scoring 100% in motion history image (MHI), 98.77% in motion energy image (MEI), 93.28% in average motion energy image (AMEI), 94.68% in enhanced motion energy image (EMEI), and 95.62% in motion entropy image (MEnI).

High power density energy harvesting and human motion monitoring with [trimethylchloromethyl ammonium][CdCl3]/polymer composite

•High power density energy harvesting with hybrid perovskite composites •Hybrid perovskite piezoelectric sensors are able to monitor delicate human motions •Interfacial molecular interactions between the hybrid perovskite and polymer Piezoelectric hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for the development of self-powered electronic devices. These hybrid systems generally have low elastic moduli and are also intrinsically brittle, limiting their applications in mechanical-to-electrical energy conversion. Here, we report the synthesis of TMCM-CdCl3/PDMS (TMCM, trimethylchloromethyl ammonium; Cl, chloride; PDMS, polydimethylsiloxane) composites with high piezoelectricity. The TMCM-CdCl3 micro-rods can adhere with PDMS chains via the C–H···Cl interactions, leading to effective absorption of strain and corresponding efficient conversion to electric polarization. As a result, the energy harvesting devices made by the composite films give a high power density up to 115.2 μW/cm2, catching up with those of the state-of-the-art ceramic counterparts. In addition, the composite devices can harvest human motion energy and sense delicate body gestures. This work demonstrates that the piezoelectric HOIP/polymer composites can serve as promising materials for the development of self-powered flexible and wearable devices. Piezoelectric hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for the development of self-powered electronic devices. These hybrid systems generally have low elastic moduli and are also intrinsically brittle, limiting their applications in mechanical-to-electrical energy conversion. Here, we report the synthesis of TMCM-CdCl3/PDMS (TMCM, trimethylchloromethyl ammonium; Cl, chloride; PDMS, polydimethylsiloxane) composites with high piezoelectricity. The TMCM-CdCl3 micro-rods can adhere with PDMS chains via the C–H···Cl interactions, leading to effective absorption of strain and corresponding efficient conversion to electric polarization. As a result, the energy harvesting devices made by the composite films give a high power density up to 115.2 μW/cm2, catching up with those of the state-of-the-art ceramic counterparts. In addition, the composite devices can harvest human motion energy and sense delicate body gestures. This work demonstrates that the piezoelectric HOIP/polymer composites can serve as promising materials for the development of self-powered flexible and wearable devices.

Stability of thin cylindrical shells under coupled thermoelastic assumption

Kinematically nonlinear coupled thermoelasticity of the FGM cylindrical shell is investigated under heat shock. The energy and equations of motion are solved simultaneously as a system of equations for an FG cylindrical shell. The classical theory of coupled thermoelasticity is used to solve the problem. The first-order shear deformation theory for the shell is considered. Also, the terms thermal coupling and rotational inertia are included in the solution. The finite element method is employed to solve the problem numerically in the space domain and the Newmark method in the time domain. Temperature distribution across the shell thickness is assumed to be linear. The radial displacement for different values of the power law index is plotted in terms of time. The occurrence of thermal buckling is examined.

Autonomous, untethered gait-like synchronization of lobed loops made from liquid crystal elastomer fibers via spontaneous snap-through

The transition from one equilibrium state to another via rapid snap-through can store elastic energy and release it as kinetic energy for rapid motion as seen in Venus flytrap and hummingbird to catch insects mid-flight. They are explored in soft robotics for repeated and autonomous motions. In this study, we synthesize curved liquid crystal elastomer (LCE) fibers as the building blocks that can undergo buckling instability upon heated on a hot surface, leading to autonomous snap-through and rolling behaviors. When they are connected into lobed loops, where each fiber is geometrically constrained by the neighboring ones, they demonstrate autonomous, self-regulated, and repeated synchronization with a frequency of ~1.8 Hz. By adding a rigid bead on the fiber, we can fine-tune the actuation direction and speed (up to ~2.4 mm/s). Last, we demonstrate various gait-like locomotion patterns using the loops as the robot's legs.

Human motion energy harvesting backpack using quasi-zero stiffness mechanism

In this study, a quasi-zero stiffness energy harvesting backpack (QZS-EHB) is proposed. The bistable quasi-zero stiffness mechanism is constructed by paralleling a pair of positive stiffness springs and a pair of negative stiffness springs to make the vibration system more easily excited by low-frequency human motion and generate snap-through action. The bidirectional vibration is mechanically modulated into unidirectional higher speed rotation, thus improving the electromechanical conversion efficiency. The theoretical model of the bistable system is established by using the Lagrange functional method to verify the bistable mechanism. A prototype is manufactured to validate the advantages of the design. The effects of spring stiffness, load weight, and motion speed on the performance of the harvester are investigated through a series of experiments. The results show that the peak voltage is 5.11 V and the peak power is 2.37 W, and the average power of the harvester is 0.77 W, with the load of 5 kg and the speed of 10 km/h. The QZS-EHB can light up a combination of LED lamps with a total power of 6 W, charge the cell phone, and enable self-powered localization and wireless information transmission, when people are jogging with the load of 2 kg. These tests verify that the proposed design can be used for emergency power consumption of people's outdoor activities.

A passive control of Casson hybrid nanofluid flow over a curved surface with alumina and copper nanomaterials: A study on sodium alginate-based fluid

Scientists are paying close attention to Casson fluids due to their remarkable industrial and technical applications. Among the non-Newtonian substances, Casson fluid is one of the most significant types. Generally, the viscosity becomes zero at infinity shear rate for a shear-diminishing substance with zero-shear rate. In this work, the flow of a sodium alginate–based Casson hybrid nanofluid composed of copper and aluminum oxide nanoparticles is studied. The hybrid nanofluid flow is considered to be magnetically influenced and chemically reactive. Additionally, the effects of the heat source, non-Newtonian heating, thermophoretic, Brownian motion, and activation energy are considered. It is anticipated that stretching curved surface is thermally convective and that there is no mass flow. The mathematical formulation is given in the form of PDEs, which are then converted into ODEs by using suitable similarity variables. The HAM and bvp4c MATLAB function is applied on the converted ODEs to accomplish the semi-analytical and numerical solutions of the modeled equations. By contrasting the new data with those that have already been published, the correctness of current model is confirmed. According to the findings, the hybrid nanofluid over a flat surface resulted in enhancements in velocity, temperature, and concentration compared to its performance on a curved surface. The hybrid nanofluid demonstrated superior performance in terms of temperature, surface drag, concentration, and rate of heat transfer. Moreover, the velocity and temperature of the classical Newtonian model were observed to be higher on the flat surface in contrast to the curved surface. The streamlines become closer with the increasing magnetic factor, while the streamlines become farther apart with the increasing curvature parameter.

Temperature dependent tensile strength modeling and analysis of shape memory polymers with physics‐based energy equivalence principle

AbstractThe quantitative characterization of the tensile strength of shape memory polymers (SMPs) at different temperatures has always been an important research topic. In this study, the critical failure energy density of SMPs including the strain energy density, potential energy and kinetic energy of atomic motion per unit volume is first introduced. Then, based on the equivalent contribution of these energies on material failure, a temperature dependent tensile strength (TDTS) model considering the corresponding physical mechanism for SMPs is established. The model provides the quantitative relationship among temperature, Young's modulus, hardening index and the tensile strength of SMPs. Meanwhile, the predicted results of the proposed model are compared with the available TDTS of SMPs, and the agreement between theory and experiment is satisfactory. In addition, the influencing factors of tensile strength and their variation with temperature are analyzed. This work contributes the novel insight for the theoretical predictions on the TDTS of SMPs, which is helpful for the high temperature strength evaluation and property optimization.

Optimal trajectory planning of a small UAV using solar energy and wind energy

Due to size limitations and the working environment near the ground, small low-altitude unmanned aerial vehicles (UAVs) cannot carry large-area solar cells and energy storage devices. Solar energy alone has only a limited effect on the improvement of their endurance. To solve this problem, this study proposes the combination of solar energy technology and dynamic soaring technology to improve the endurance of small UAVs. Then, the optimal energy acquisition strategy based on the combination of solar energy and dynamic soaring technology is analyzed in terms of energy. The motion equations and energy acquisition and consumption models of a small solar UAV based on horizontal wind shear are established. Moreover, an optimal trajectory planning problem with the maximum charging power of rechargeable batteries as the optimization objective is proposed. The optimal trajectory is solved based on the hp adaptive pseudo-spectral method, and the optimal trajectory combining the two technologies is simulated and compared with the constant-altitude constant-velocity (CACV) trajectory of the UAV using only solar technology. The simulation results show that under the flight background of tmission = 6:00 (summer sunrise) and β = 0.125 s−1 (wind gradient of the wind shear), the optimized O-type trajectory decreased the energy consumption power by 39.86% and increased the solar energy acquisition power by 86.34% compared to the CACV trajectory. Consequently, the small UAV stores more energy in the rechargeable batteries to improve the endurance performance. Compared to the environment where the sun is located on the leeward side of the wind shear, the environment where the sun is located on the windward side of the wind shear can enable the UAV to acquire more energy through the optimized O-type trajectory.

Neuron‐Inspired Self‐Powered Hydrogels with Excellent Adhesion, Recyclability and Dual‐Mode Output for Multifunctional Ionic Skin

AbstractHydrogels are promising materials for electronic skin due to their flexibility and modifiability. Reported hydrogel electronic skins can recognize stimulations and output signals, but the single output signal and the requirement of external power source limit their further applications. In this study, inspired by the neuron system, the self‐powered neuron system‐like hydrogels based on gelatin, water/glycerin and ionic liquid modified metal organic frameworks (MOFs) are prepared. The optimized hydrogel exhibits excellent adhesion (40 kPa), stretchability (0%–100%), water retention (>92% at 0% relative humidity (RH) atmosphere), ionic conductivity (>10−3 S m−1) and stability (>30 days). Besides, the neuron system‐like hydrogels are highly sensitive to pressure (0—10 N) and humidity (0%–75% RH) with dual‐modal output, without external power source. Finally, the optimized hydrogel ionic skin is applied in human motion detection, energy harvesting, and low humidity sensing. This study provides a preliminary exploration of self‐powered ionic skin for multi‐application scenarios.

Degradation Behavior and Mechanism of Metalized Film Capacitor Under Ultrahigh Field

Metalized film capacitor degradation under ultrahigh electric fields is crucial for the reliability of voltage source converter (VSC)-HVDC systems. In the present study, systematic investigations were performed that metalized film capacitors were aged under the dc electric field ranging from 300 to 400 kV/mm. Results showed that under moderate electric field, the capacitance reduction of sample capacitors presented two stages with different decay rates. With the increase of the electric field, the rapid degradation occurred immediately on the starting of the aging process, suggesting a voltage threshold determining the capacitors’ stability. In addition, the degradation mechanisms of both metalized films and biaxial oriented polypropylene (BOPP) base films were investigated by statistical analysis and structural experiments. Below the voltage threshold, more shallow traps were generated and the activation energy of molecular motions was reduced due to PP molecules scissions, resulting in the decrease of breakdown strength (BDS) of BOPP films. While above the voltage threshold, the accelerated failure could be attributed to two main causes: the fast breakdown of originally formed weak points and the dramatically increased self-healing area. The study can contribute to the design and evaluation of dc-link capacitors both experimentally and theoretically.

Dim and Small Target Detection Based on Spatio-Temporal Filtering and High-Order Energy Estimation

To improve the detection ability of infrared dim and small targets in complex cloud backgrounds, we present a novel method based on motion energy estimation. First, according to the characteristic of the gradient between the target and the background, we propose a new diffusion function and combine with the gradient difference to complete the background suppression. Then an improved high-order correlation algorithm is proposed to enhance the target signal through the motion correlation properties of the target, which build the gradient difference discrimination model between the target and four adjacent directions to establish the region of interest model, then realizes the high-order energy enhancement of the region of interest and further eliminate the clutters at the same time. Finally, the motion model of the target in the inter-frame spatial-temporal domain is constructed to estimate the motion direction of the target, then realizes the target energy accumulation along the motion direction and obtains the maximum energy of the target to detect the real target. In the experiment, we select six scenes for testing, the experimental results show that the proposed method has an excellent detection performance compared with six traditional detection algorithms in infrared dim and small target detection.

Method for Determining Effective Frequency Range of Coherency Based on Seismic Energy

When using data recorded by dense instrument arrays to fit the coherency model of spatial variation of seismic ground motions, the selected frequency range may affect the fitting parameters, which also affects the synthesized time history of the ground motion field. In this study, the acceleration of the 5th and the 45th Earthquake of the SMART-1 array was selected. The Abrahamson and Loh models were used to perform the parameter fitting of the coherency for frequency ranges of 0–8, 0–16 and 0–24[Formula: see text]Hz, and the obtained results were different. The smaller the frequency range, the lower the fitted lagged coherency. The influence of frequency range on fitting parameters of Loh model is much greater than that of Abrahamson model. Based on the relative relationship of ground motion energy distribution in each frequency band represented by the power spectra, from the perspective of power spectrum energy, the energy ratio concept was introduced, i.e. the ratio of the power spectra for a specific frequency range to the total power spectra. Based on the energy ratio, a method for determining the effective frequency range of the coherency model was developed. Through the comparison and analysis of the horizontal-component acceleration of the SMART-1 array, it was found that when the frequency range was 0–5[Formula: see text]Hz, the energy ratio exceeded 95%, when the frequency range was 0–8[Formula: see text]Hz, the energy in the frequency band reached approximately 99% of the total energy. Therefore, it is recommended that when the parameters of the coherency model are fitted, the frequency corresponding to an energy ratio of 95% can be used as the effective frequency. Within this range, the contamination of high-frequency components on the fitting results is minimized.

Unraveling the ferroelectric switching mechanisms in ferroelectric pure and La doped HfO2 epitaxial thin films

Epitaxial orthorhombic phase La doped HfO2 films are promising for achieving robust ferroelectric polarization without wake-up effect. However, lowering the coercive field is crucial for achieving low-power memory devices.In this work, we have investigated the influence of the La content effect on the structural and ferroelectric properties of epitaxial HfO2 thin films. We show that while the remanent polarization is optimum for 2–5 at. % La-doped HfO2 films, the coercive field is decreased with La doping. The experimental work is supported by density functional theory (DFT) calculations which show that the polarization switching in epitaxial La:HfO2 films can be understood based on the synergetic contribution of the presence of a non-ferroelectric monoclinic phase and the La doping itself that causes a reduction of the nucleation and DW motion energy barriers for the crossing path, which makes it more probable than the non-crossing one.

Preliminary Study for the Commercialization of a Electrochemical Hydrogen Compressor

A global energy shift to a carbon-neutral society requires clean energy. Hydrogen can accelerate the process of expanding clean and renewable energy sources. However, conventional hydrogen compression and storage technology still suffers from inefficiencies, high costs, and safety concerns. An electrochemical hydrogen compressor (EHC) is a device similar in structure to a water electrolyzer. Its most significant advantage is that it can accomplish hydrogen separation and compression at the same time. With no mechanical motion and low energy consumption, the EHC is the key to future hydrogen compression and purification technology breakthroughs. In this study, the compression performance, efficiency, and other related parameters of EHC are investigated through experiments and simulation calculations. The experimental results show that under the same experimental conditions, increasing the supply voltage and the pressure in the anode chamber can improve the reaction rate of EHC and balance the pressure difference between the cathode and anode. The presence of residual air in the anode can impede the interaction between hydrogen and the catalyst, as well as the proton exchange membrane (PEM), resulting in a decrease in performance. In addition, it was found that a single EHC has a better compression ratio and reaction rate than a double EHC. The experimental results were compatible with the theoretical calculations within less than a 7% deviation. Finally, the conditions required to reach commercialization were evaluated using the theoretical model.