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The increasing complexity and dynamics of the stock trading market are major challenges for the financial industry and are primary dilemmas for all countries nowadays. In addition, the stock trading market has a considerable impact on the global economy, and its importance is self-evident. To cope with the complexity and dynamics of a stock trading market, this paper applies complex network theory and model to explore the topology of the global stock trading network. First, this paper collects stock trading data from 74 countries from 1999 to 2020. It converts the collected stock trading data of these countries into a complex network using a type of algorithm based on the time series visibility graph (VG) algorithm. Then, the data are analyzed by a complex network model, and six analytical metrics are obtained. Finally, the six metrics are analyzed by the entropy weight method to identify the key nodes in the network and to obtain the ranking of each country's stock trading data. This paper is an effective application of complex network and entropy weight method in stock trend analysis, which mainly includes two contributions. First, the VG algorithm provides a novel research perspective for modeling the global stock trading trend. Second, key nodes in the network are analyzed and identified based on the entropy weight method, and the ranking of key nodes in the stock trading network is obtained, which provides a new method for further research on the stock trading trend, investment portfolio, and stock return forecasting. [ABSTRACT FROM AUTHOR]

This paper proposes the generalized maintenance policies for a computing system when the copula functions model the interdependency. In this paper, the dependence between the components has been modeled by three copula functions. We deal with random maintenance policies for repairable parallel systems with n dependent or independent components. Firstly, we discuss the maintenance first and last policies for parallel systems composed of dependent components. We consider the random maintenance policy for parallel systems that are dependent and attempt to find the optimal maintenance time by considering the copula framework. The expected cost rate is considered as objective function to minimize. For each policy, the optimal maintenance time that minimizes the mean cost rate is analyzed and discussed numerically. And we study the effects of model parameters on the optimal maintenance policy and compare the copula. The findings of the paper extend the results in the literature from system with independent components to dependent components. Numerical results are presented for components lifetime follow Weilbull distribution. Therefore manager can use the results to formulate the optimal decision problem of their parallel systems with dependent components. [ABSTRACT FROM AUTHOR]

In data-driven prognostics and health management (PHM), most studies focus only on prognostics performance but rarely consider maintenance decision problems. However, simple predictive maintenance decisions are not effective in dealing with the complex operating conditions faced in modern industrial systems. Thus, we propose a complete data-driven dynamic predictive maintenance strategy for system remaining useful life (RUL) prediction via deep learning ensemble method to solve this problem. This deep learning ensemble method is composed of a convolutional neural network (CNN) and a bidirectional long short-term memory network (Bi-LSTM), which aims to effectively predict the system RUL. Then, we consider a dynamic predictive maintenance strategy with uncertain system mission cycles based on the RUL predicted by deep learning ensemble method. Meanwhile, this dynamic predictive maintenance strategy includes order, stock, and maintenance decisions. In addition, the number of missions performed by the system and the reliability of the last performed mission are presented based on the mission cycle and the predicted RUL. Finally, experimental results from the NASA turbofan engine dataset C-MAPSS show the favorable performance of the proposed dynamic predictive maintenance strategy compared to the existing maintenance strategy. • We propose a complete data-driven dynamic predictive maintenance strategy based on prognostics information. • We consider the impact of the system mission cycles on the maintenance strategy according to the predicted RUL. • A cost-effective order and stock management decision is considered in dynamic predictive maintenance strategy, in addition to making maintenance strategy. • Based on the predicted RUL, the number of missions performed by the system and the reliability of the performed mission are presented. [ABSTRACT FROM AUTHOR]

The refugee problem is one of the most important issues facing the international community today. It not only troubles the countries where refugees are generated but also has a great impact on the countries where refugees are influx. With the continuous development of globalization, the refugee problem is no longer a problem of a country or a region, but a global problem faced by the international community. To cope with the global refugee problem, this paper analyzes the number of refugees in 156 countries from 1990 to 2020 and transforms the refugee population data of these countries into a complex network through a time series visibility graph (VG) method. First, we categorize the income level of 156 countries and analyze the impact of income level on the increase of refugee numbers. Then, the evaluation index of the number of refugees is obtained through the VG method. Finally, a TOPSIS comprehensive evaluation method based on the entropy weight approach is employed to analyze the data. This paper includes two main contributions. First, the application of the VG method provides a new perspective for enriching the modeling of the global refugee population growth trend. Second, this paper shows that the TOPSIS evaluation method based on the entropy weight method is effective, which provides a new method for further research on the global refugee population growth trend. [ABSTRACT FROM AUTHOR]

Internal short circuit (ISC) of lithium-ion batteries (LIBs) would be triggered due. to inevitable electric vehicle collision, which pose serious threats to the safety and stability of the battery system. However, there is a lack of research on the ISC mechanism of LIBs under dynamic impact loadings. In this work, a coupled multi-physics model to describe the mechanical, electrical, and thermal response of LIBs under dynamic loading is established. The model can well predict the ISC and thermal runaway evolution process of LIBs with various SOCs under different impact energies. Four ISC modes are revealed through disassembling the LIBs after dynamic loading. Further, a strain-based ISC criterion is proposed to describe the triggering and voltage drop characteristics of each ISC mode. Subsequently, the mechanical-electrical-thermal behavior of LIBs in quasi-static and dynamic loading is compared and analyzed. Afterward, the triggering impact energy of four ISC modes for LIBs with different SOCs is concluded. The model proposed in this paper is currently based on small-sized batteries, and further study is required to extend its application to large-sized batteries. [Display omitted] • A multi-physics coupling model to describe dynamic mechanical-electrical-thermal response of LIB is developed. • ISC mechanism under dynamic loading is revealed through battery disassembling and simulation. • The mechanical-electrical-thermal behaviors of LIBs in quasi-static and dynamic loading are compared. • A triggering impact energy map of each ISC mode for LIBs with various SOCs is established. [ABSTRACT FROM AUTHOR]

Abstract The safety design of systems using lithium-ion batteries (LIBs) as power sources, such as electric vehicles, cell phones, and laptops, is difficult due to the strong multiphysical coupling effects among mechanics, electrochemistry and thermal. An efficient and accurate computational model is needed to understand the safety mechanism of LIBs and thus facilitate fast safety design. In this work, a detailed mechanical model describing the mechanical deformation and predicting the short-circuit onset of commercially available 18650 cylindrical battery with a nickel cobalt aluminum oxide (NCA) system is established for the first time. The mechanical properties of anode, cathode, and separator are characterized. Based on the experiment results, the constitutive models of component materials are established and validated through numerical simulations. A detailed computational model including all components (i.e., separator, anode, cathode, winding, and battery casing) is then developed by evaluating four typical mechanical-loading conditions. Short-circuit criteria are subsequently established based on the separator failure, thereby enabling the mechanical model to predict the short circuit electrochemically. Results show that the model can describe LIB behaviors from mechanical deformation to internal short circuit. Results provide a powerful tool for the safety design of LIBs and related engineering systems. Graphical abstract Image 1 Highlights • A model describing the deformation and short-circuit onset is established. • Constitutive models of each component are developed based on the experiments. • Short-circuit criteria are established based on the separator failure. • Short-circuit triggering behavior under dynamic loading is discussed. [ABSTRACT FROM AUTHOR]

Abstract The cylindrical lithium-ion battery has been widely used in 3C, xEVs, and energy storage applications and its safety sits as one of the primary barriers in the further development of its application. Among all cell components, the battery shell plays a key role to provide the mechanical integrity of the lithium-ion battery upon external mechanical loading. In the present study, target battery shells are extracted from commercially available 18,650 NCA (Nickel Cobalt Aluminum Oxide)/graphite cells. The detailed material analysis is conducted to reveal a full understanding of the material. Then, the dynamic behavior of the battery shell material is experimentally investigated. Both theoretical constitutive and numerical models have been developed, capable to describe mechanical behaviors of the battery shell material upon impact loading. It is the first time to discover that the strain rate effect of the shell material shall be considered for the mechanical integrity of the battery and high strength of the shell material may contribute to an early short-circuit triggering. The quantitative relationship is also established between short-circuit and material strength. Results lay a solid foundation towards providing a theoretical safety design guidance for the shell material choice of cylindrical lithium-ion batteries. Graphical abstract Unlabelled Image Highlights • Dynamic experiments were designed and conducted for battery shell • Mechanical behaviors were studied considering direction, strain rate and stress triaxiality index • A strain rate dependent constitutive model with fracture criterion was established • Finite element models were established to verify the constitutive model • Strain rate and strength effect on short-circuit property were discussed [ABSTRACT FROM AUTHOR]

Mechanical properties of electrode materials have significant influence over electrochemical properties as well as mechanical integrity of lithium-ion battery cells. Here, anode and cathode in a commercially available 18650 NCA (Nickel Cobalt Aluminum Oxide)/graphite cell were comprehensively studied by tensile tests considering material anisotropy, SOC (state of charge), strain rate and electrolyte content. Results showed that the mechanical properties of both electrodes were highly dependent on strain rate and electrolyte content; however, anode was SOC dependent while cathode was not. Besides, coupled effects of strain rate and SOC of anodes were also discussed. SEM (scanning electron microscope) images of surfaces and cross-sections of electrodes showed the fracture morphology. In addition, mechanical behavior of Cu foil separated from anode with different SOC values were studied and compared. Finally, constitutive models of electrodes considering both strain rate and anisotropy effects were established. This study reveals the relationship between electrochemical dependent mechanical behavior of the electrodes. The established mechanical models of electrodes can be applied to the numerical computation of battery cells. Results are essential to predict the mechanical responses as well as the deformation of battery cell under various loading conditions, facilitating safer battery design and manufacturing. [ABSTRACT FROM AUTHOR]

This paper studies a new large-scale emergency medical services scheduling (EMSS) problem during the outbreak of epidemics like COVID-19, which aims to determine an optimal scheduling scheme of emergency medical services to minimize the completion time of nucleic acid testing to achieve rapid epidemic interruption. We first analyze the impact of the epidemic spread and assign different priorities to different emergency medical services demand points according to the degree of urgency. Then, we formulate the EMSS as a mixed-integer linear program (MILP) model and analyze its complexity. Given the NP-hardness of the problem, we develop two fast and effective improved discrete artificial bee colony algorithms (IDABC) based on problem properties. Experimental results for a real case and practical-sized instances with up to 100 demand points demonstrate that the IDABC significantly outperforms MILP solver CPLEX and two state-of-the-art metaheuristic algorithms in both solution quality and computational efficiency. In addition, we also propose some managerial implications to support emergency management decision-making. [ABSTRACT FROM AUTHOR]

• An anisotropic model describing dynamic mechanical responses of LIBs is established. • Dynamic failure mechanism is revealed through micro-CT analysis and simulation. • Increasing SOC leads to a higher failure threshold of LIBs. • Slant shear cracks inside the battery after impact deformation are observed. • The failure threshold of LIBs at multiple SOCs under various impact masses and shapes is established. Most of the mechanical abuse to which lithium-ion batteries (LIBs) are subjected in real-life scenarios is dynamic, and the safety issues involved are cause for concern. An accurate dynamic failure threshold is needed for both safety assessment and engineering protection of LIBs. In this work, the dynamic mechanical response and external voltage behavior of 18650 cylindrical LIBs with various state of charge (SOC) values are investigated via drop weight tests firstly. Then, a novel anisotropic model, incorporating the SOC effects and damage settings, is developed. The model can well predict the mechanical behaviors of LIBs for both quasi-static loading and dynamic radial compression. In addition, a satisfactory consistency is achieved between the cracks formed within the battery and the micro-CT scanning results. Further, a two-stage failure criterion defined by the jellyroll equivalent plastic strain is proposed, based on two special failure modes of LIBs, namely electrochemical failure and structural failure. The failure threshold for LIBs with multiple SOCs is established at various impact masses and shapes. Results provide a high-fidelity computational model for the battery safety behaviors upon dynamic mechanical loading and guidelines for the design of next-generation robust batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Mechanical properties of separators have a great impact on the electrochemical performance of lithium ion battery, such as capacity, charge/discharge behavior, charging cycles and among others. In the present study, two typical widely commercialized separators, Celgard 2400 and Celgard 2340, are the investigation objects with single layer and three-layer structures respectively. Firstly, to investigate material anisotropy and strain rate effects, tensile tests conducted on MTS and Instron at various strain rates from 0.01 to 50 s − 1 are carried out with samples prepared at three different directions: transverse direction (TD, 0°), machine direction (MD, 90°) and 45°. The failure strain decreases while failure stress increases with the strain rate for materials in all three directions. Material anisotropy is observed within the porous structure with nanofiber reinforced in the polymer matrix. Secondly, the environmental solvent effect is also examined: dimethyl carbonate (DMC) solution has a negative effect on the mechanical property of the separator while water may exert a positive effect. Furthermore, DMA Q800 is employed to study the viscoelasticity of separators at various temperatures and frequencies. A simple viscoelastic model based on Kelvin–Voigt model is proposed for the two types of separators. This research may serve as a solid step towards the comprehensive understanding of LIB separator and shed light on the future research of unveiling physical relation between mechanical properties and electrochemical performance of LIB. [ABSTRACT FROM AUTHOR]

The air kerma, which is the amount of energy given off by a radioactive substance, is essential for medical specialists who use radiation to diagnose cancer problems. The amount of energy that a photon has when it hits something can be described as the air kerma (the amount of energy that was deposited in the air when the photon passed through it). Radiation beam intensity is represented by this value. Hospital X-ray equipment has to account for the heel effect, which means that the borders of the picture obtain a lesser radiation dosage than the center, and that air kerma is not symmetrical. The voltage of the X-ray machine can also affect the uniformity of the radiation. This work presents a model-based approach to predict air kerma at various locations inside the radiation field of medical imaging instruments, making use of just a small number of measurements. Group Method of Data Handling (GMDH) neural networks are suggested for this purpose. Firstly, a medical X-ray tube was modeled using Monte Carlo N Particle (MCNP) code simulation algorithm. X-ray tubes and detectors make up medical X-ray CT imaging systems. An X-ray tube's electron filament, thin wire, and metal target produce a picture of the electrons' target. A small rectangular electron source modeled electron filaments. An electron source target was a thin, 19,290 kg/m3 tungsten cube in a tubular hoover chamber. The electron source–object axis of the simulation object is 20° from the vertical. For most medical X-ray imaging applications, the kerma of the air was calculated at a variety of discrete locations within the conical X-ray beam, providing an accurate data set for network training. Various locations were taken into account in the aforementioned voltages inside the radiation field as the input of the GMDH network. For diagnostic radiology applications, the trained GMDH model could determine the air kerma at any location in the X-ray field of view and for a wide range of X-ray tube voltages with a Mean Relative Error (MRE) of less than 0.25%. This study yielded the following results: (1) The heel effect is included when calculating air kerma. (2) Computing the air kerma using an artificial neural network trained with minimal data. (3) An artificial neural network quickly and reliably calculated air kerma. (4) Figuring out the air kerma for the operating voltage of medical tubes. The high accuracy of the trained neural network in determining air kerma guarantees the usability of the presented method in operational conditions. [ABSTRACT FROM AUTHOR]

Safety issues have become one of the most critical bottlenecks for the further wide application of lithium-ion batteries (LIBs) as power sources in electrified vehicles. Specifically, the understanding of the electrochemical integrity of LIBs upon mechanical abuse is in pressing need. To this end, we design and conduct ex-situ experiments on anodes with various state-of-charges (SOCs) to study the coupled electrochemical and mechanical behavior of graphite anode. A multiscale computational model considering the lithium-ion intercalation is established and validated. By exploring the combination of experiments and model computation, we discover that the lithiation process increases the density of the binder material as well as the yield stress such that the anode behaves stiffer with higher SOC. The failure strain decreases as SOC increases, and failure first occurs in the active layer. Such densification of the binder material stems from the elastic and plastic expansion of the active particle and the mechanical property mismatch between the active particles and binder. Results highlight the important role of the binder in the safety behaviors of LIBs upon stress and deepen the understanding of the structure-property relation of the anode materials, facilitating the design for next-generation robust LIBs. [Display omitted] • A multiscale computational model of anode is established and validated. • SOC-dependent failure of the binder is responsible for the anode behavior. • The main factor causing the obvious SOC dependency of the anode is revealed. • Binder properties are parametrically discussed and summarized for future design. [ABSTRACT FROM AUTHOR]

As a basic industry in the country's development, the transportation industry has a significant relationship to its normal operation for developing and constructing the national economy. The increase in carbon emissions from transport is an increasingly growing problem, and countries worldwide are also taking measures to reduce emissions. Using time series data over the period from 1990 to 2016, this paper applies the visibility graph approach to transform it into a complex network and excavate some information about the data, then evaluates all countries based on the TOPSIS method. We find that the development of transportation is an important symbol to measure the degree of modernization of a country's transportation, and low-income countries have lower carbon emissions due to slower transportation development. The results of transportation carbon emissions are especially encouraging for the Chinese government given its long-term and sustained efforts to expand railway and waterway infrastructure, and provide a new perspective for further research on the development trend of global transportation carbon emissions. Meanwhile, it is urgent to speed up the development and use of clean energy for economically developed countries. [ABSTRACT FROM AUTHOR]

To enable the understanding of the internal short circuit mechanism triggered by separator failure, mechanical indentation loadings are designed to create the deformation of the separator in a precisely controllable way. Herein, two characteristic short-circuit types are observed in anode-separator-cathode stack upon mechanical abusive loading, i.e., rapid and gentle voltage drop. Through the ex-situ experiment, the rapid voltage drop is due to the direct contact between cathode and anode as a result of separator fracture, while the gentle voltage drop is related to the flattening of the separator with the absence of its function to isolate electron transfer. The developed detailed numerical models, considering the failure of anode and cathode and the anisotropy of separator, can well describe the mechanical responses of components and stack. Thanks to the numerical computation model and computation, we establish and validate the generalized short-circuit criteria for the two representative failure modes based on the volumetric strain and equivalent strain of separator. Results provide a powerful and generalized tool aiming for the design of next-generation separator technology, enabling a more fundamental and effective way for future ISC detection, monitoring, and evaluation which can be embedded within the battery management system. Image 1 • Two representative short circuit modes are related to separator deformation status. • A detailed computational model of anode-separator-cathode stack is established. • A constitutive model of separator with mechanical anisotropy is developed. • Universal separator failure criteria for short circuit are proposed and validated. [ABSTRACT FROM AUTHOR]

Deformation and failure behaviors of the anode material play important roles in internal short-circuit and thermal runaway behaviors of lithium-ion batteries. In previous research, we discovered that anode behaves significantly different in constitutive behaviors at various strain rates. To unravel the fundamental mechanism, a multiscale detailed computational model describing anode behavior is established in the present study. Numerical simulation results of anode material show that the established model has a good correlation with the experiments for the description of the mechanical behaviors of the anode at strain-rates from 5 × 10−4/s to 1 × 10−1/s. This model shows that the high strain-rate dependency of the failure of the active material should be responsible for the observed deformation behavior of the anode material. Meanwhile, it is found that the particle size distribution and mechanical properties of the binder have an influential effect on the yield strength value of the anode. Results clarify the fundamental reasons for the behaviors of anode material, which may support the design of safer and more robust batteries. Image 1 • A multiscale detailed computational model describing anode behavior is established. • Strain-rate dependent failure of the active material is responsible for the anode behavior. • The binder contents and its mechanical properties effect is discussed. • Interfacial strength between active layer and copper foil is studied. [ABSTRACT FROM AUTHOR]

The acceleration of fast charging capabilities has emerged as a pivotal objective within the realms of the battery, electric vehicle, and energy storage sectors. However, the classical electrochemical models are not able to describe voltages of the cell (Ucell), anode (Ua), and cathode (Uc) at high C‐rates. Herein, Ucell, Ua,, and Uc are experimentally obtained under various C‐rates (0.1–2C) and identified the charge transfer resistance of the cathode (RCT,c) as the primary rate‐limiting factor. Thus, the anode is established as a multi‐scale coupling model with Fick's law and phase separation model applied, to discuss their effect on Ua and Li‐ion concentration prediction. 2D reconstruction structures for the cathode is established with RCT,c effect considered. Finally, the Ua, Uc, and Ucell are successfully predicted at different C‐rates. Results propose an accurate and versatile electrochemical model and highlight the importance of considering limiting factors in electrochemical modeling for fast charging. [ABSTRACT FROM AUTHOR]

Important nodes can determine the internal structure of complex networks and reveal the internal relationships of real-world systems, and identifying key nodes in complex networks is one of the important research areas of complex network science. As the king of commodities, changes in the price of gold significantly impact the economic development of various countries. Especially in the early stages of the outbreak of war between Russia and Ukraine, the price of gold futures has been greatly impacted, and the systemic risks are gradually spreading. In this paper, a gold future price series is mapped into a visibility graph (VG), the characteristics of the gold price time series and key points-in-time, have been explored from the perspective of complex network. First, according to the data structure characteristics of gold futures, this paper converts the closing prices of gold futures of the New York Mercantile Exchange into a complex network through the VG model. Then, by using the complex network model to further delve into the price of gold futures, it is found that the degree distribution of the gold futures network follows a power-law distribution, and has obvious scale-free characteristics. Finally, this paper uses the visual network node shrinking algorithm and the technique for order preference by similarity to ideal solution (TOPSIS) analysis method to identify the key nodes of the gold futures visual map to find the key time nodes in the timeline of gold futures market. Analysis of the key time nodes of this market by four methods reveals that the repetition rate of the key time nodes in the methods' top 10 ranking is as high as 82.5%, indicating that the results obtained in this paper are robust. This study introduces a new model to describe the characteristics of gold futures price series, one which can find key time nodes in gold futures prices and provide potential help for predicting gold futures prices. [ABSTRACT FROM AUTHOR]

Abstract The windshield is one of the important components of a vehicle for pedestrian protection. Thin chemically toughened glass (TG) is regarded as a promising substitute for soda–lime glass in traditional soda–lime laminated glass (SLG). The mechanical behavior of TG and toughened laminated glass (TLG) is experimentally studied. Finite element models based on experiment results are established and validated. The pedestrian protection characteristics of the TLG windshield are numerically investigated and compared with its counterpart, the SLG windshield. A significant decrease in head injury criteria in the TLG windshield compared with the SLG windshield is observed with the significant weight reduction of the TLG windshield. Finally, parametric studies on the effect of impact velocity, location, and angle are conducted. Results show the reasonable pedestrian protection capability of the TLG windshield, and they provide useful design tools and practical evaluation guidance for safe and light laminated windshields. Graphical abstract Image 1 Highlights • Mechanical behavior of TG and TLG are experimentally investigated. • Numerical simulation predictions by proposed TLG FE model are presented. • Parametrized analysis of TLG windshield FE model is conducted. • Pedestrian protection safety assessment of TLG windshield is obtained. [ABSTRACT FROM AUTHOR]

Honeytubes, a novel type of honeycomb formed by reinforcement with lattice trusses, were reported to exhibit enhanced buckling resistance. However, an in-depth analysis for the compressive performance and energy absorption capacity was lacking. In this paper, the effects of microstructure and tube alignment on compressive properties were studied. Four types of honeytubes were designed based on different topologies, geometries and tube patterns, and fabricated by selective laser sintering (SLS). Out-of-plane compression tests and finite element simulation were performed for the analysis. Results indicated that incorporation of lattice in honeycombs resulted in greater local strain in tubes and tube-rib connections. However, honeytubes exhibited superior energy absorption capability, even surpassing that of some metallic lattices. Balancing the configuration of tubes in honeytubes could ensure enhanced mechanical performance. This work demonstrates that materials designed by capitalizing on micro-topologies can regulate mechanical properties and provide insights for guiding the development of new materials. [ABSTRACT FROM AUTHOR]

Metallic Lithium deposited on graphite particles is the major phenomenon responsible for the degradation of cell capacity, triggering of internal short circuit (ISC), and exacerbating thermal runaway (TR) in lithium‐ion batteries (LIBs). However, currently, no available physics‐based model can provide an accurate quantitative description of lithium‐plating behavior. Herein, this work establishes a mechanism model to characterize the Li deposition‐stripping process, especially the formation of dead Li and the reversibility of deposited Li. By the combination of the battery model and 3D particle model with the Li deposition‐stripping model, this work enables the quantitative prediction of Li deposition during charging–discharging cycles at various charging rates. Based on the revealed understanding of the Li deposition‐stripping process, a smart charging strategy with the optimization of the minimized Li‐deposition and expedited charging time is proposed. Furthermore, this work also quantifies the influence of anode heterogeneity on Li plating. The results highlight the promise of physics‐based mechanistic modeling for the quantification of the Li disposition‐stripping process and provide fundamental guidance on battery design and charging protocols for next‐generation long cycle life Li‐ion cells. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are currently widely used in various industries, including automotive industry. Thus, the study of battery mechanical integrity subject to dynamic loading is critical for vehicle safety, which still remains rare. In this paper, first of all, by taking the advantage of previous efforts on quasi-static mechanical experiments on lithium-ion batteries, a new battery mechanical integrity criteria is suggested based on the mechanical strength theory. Further, by considering the strain rate and inertia effect of the battery structural and material, the dynamic mechanical behavior of lithium-ion battery is investigated. Different mechanical failure behaviors are obtained through the combination of numerical simulation and the suggested battery mechanical integrity criteria. Finally, parametric studies are carried out to further comprehensively reveal the battery dynamic mechanical integrity behavior. Results may shed lights on the lithium-ion battery dynamic mechanical behavior and safety research. [ABSTRACT FROM AUTHOR]

The improvement of the environmental efficiency in the power industry is crucial in promoting energy conservation and emission reduction to achieve sustainable development. This study constructs a multi-hierarchy meta-frontier BAM model to measure environmental efficiency considering technological and regional heterogeneity. Using this model, we measure and decompose the environmental efficiency of the power industry in 30 Chinese provinces during 2008–2020. The main results are as follows. (1) Beijing and four other provinces have the highest environmental efficiency among the high-technology group, while Jiangsu and Hainan have the highest environmental efficiency among the medium-technology and low-technology groups, respectively. There are significant differences in environmental efficiency among provinces within each technology group. (2) Regional and technical inefficiencies in the high-technology and medium-technology groups are the main factors influencing inefficiency. However, the inefficiency of the low-technology group is 0.36, while technical inefficiency is 0.34. (3) The environmental efficiency of all three technical groups has improved as a result of technological progress. Environmental efficiency improvement is the largest in the high-technology group but only by 1%. This study extends conventional approaches of environmental efficiency assessment and enhances the comprehension of the operation of the power industry in various Chinese provinces. The research outcomes provide insights for formulating more precise and effective strategies towards the sustainable evolution of China's power sector. • The efficiency is measured by the combined model from a new perspective. • The technology, the management, and the regional heterogeneity are studied. • Each efficiency of each province is ranked as follows, RE > TE > ME. • The environmental efficiency improved in all three technical groups. [ABSTRACT FROM AUTHOR]

Li plating is considered as the major cause for the capacity degradation, resistance increase, and early short circuit of the cell. Due to the highly nonlinear and interdisciplinary nature, quantitative modeling of the Li plating process at the cell level is not available. Herein, we established a physics-based detailed model to describe the Li plating behaviors in a pouch cell level. The distribution of the current density and over-potential accurately predict the higher possibility of Li plating in the inner anode layers than the out layers. We discover that the larger thickness of the anode is more prone to have Li plating due to the liquid phase potential. The conductivity of electrolyte and diffusivity of Li-ion in cathode increase the Li plating risk while higher diffusivity of Li-ion in anode leads to a reduced risk. Battery charging mode also has a nontrivial influence on the Li plating probability. More importantly, the tab positions play a dominant role in the Li plating risk. Results unlock the fundamental working mechanism of Li plating in various design parameters and working scenarios, as well as provide a detailed modeling framework for the guidance of the next-generation long-cycle battery designs. • A 2D model considering the actual winding structure of the battery is established. • The over-potential distribution is analyzed to predict risk of Li plating. • The relationship between the risk of Li plating and vital design parameters is clarified. • Appropriate design and use of the battery is proposed to reduce the risk of Li plating. [ABSTRACT FROM AUTHOR]