Structural Designs for Accommodating Volume Expansion in Sodium Ion Batteries

T At the forefront of energy storage field, developing sodium ion batteries （SIBs） has drew a wide concern due to relatively low cost and abundant resource, comparing with lithium ion batteries （LIBs）. Serious volume expansion constraints the electrochemical performance of the conver- sion/alloying materials, despite of their high reversible capacities or theoretical capacities. Here, from the perspective of structural designs, we systemat- ically study four types of routes to accommodate volume expansion. Delicate and peculiar nanostructures based on nanocrystallization engineering are widely focused on, covering nanosheet assembly and nanoarray construction. Robust materials such as carbon-based materials can be utilized as the buffer matrix, mitigating the mechanical stress during the charge/discharge process. Besides, recent studies have demonstrated void space reservation in nanostructures was also beneficial for adapting to volume changes. Moreover, for conversion materials, numerous works have confirmed the advanta- geous influence of interlayer spacing regulation. We also explained the superiority and challenges for further giving scope to structural designs. Sketching out the future studies in SIBs, in situ characterizations are supposed to be highlighted, as well as in-depth researches on the stress evolution caused by volume expansion.

Recent Advances in Structural Optimization and Surface Modification on Current Collectors for High‑Performance Zinc Anode:Principles,Strategies,and Challenges

The last several years have witnessed the prosperous development of zinc-ion batteries(ZIBs),which are considered as a promising competitor of energy storage systems thanks to their low cost and high safety.However,the reversibility and availability of this system are blighted by problems such as uncontrollable dendritic growth,hydrogen evolution,and corrosion passivation on anode side.A functionally and structurally well-designed anode current collectors(CCs)is believed as a viable solution for those problems,with a lack of summarization according to its working mechanisms.Herein,this review focuses on the challenges of zinc anode and the mechanisms of modified anode CCs,which can be divided into zincophilic modification,structural design,and steering the preferred crystal facet orientation.The possible prospects and directions on zinc anode research and design are proposed at the end to hopefully promote the practical application of ZIBs.

The action mechanisms and structures designs of F-containing functional materials for high performance oxygen electrocatalysis

Non-renewable fossil fuels have led to serious problems such as global warming,environmental pollution,etc.Oxygen electrocatalysis including oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)plays a central role in clean energy conversion,enabling a number of sustainable processes for future air battery technologies.Fluorine,as the most electronegative element(4.0)not only can induce more efficient regulation for the electronic structure,but also can bring more abundant defects and other novel effects in materials selection and preparation for favorable catalysis with respect to the other nonmetal elements.However,an individual and comprehensive overview of fluorine-containing functional materials for oxygen electrocatalysis field is still blank.Therefore,it is very meaningful to review the recent progresses of fluorine-containing oxygen electrocatalysts.In this review,we first systematically summarize the controllable preparation methods and their possible development directions based on fluorine-containing materials from four preparation methods.Due to the strong electron-withdrawing properties of fluorine,its control of the electronic structure can effectively enhance the oxygen electrocatalytic activity of the materials.In addition,the catalytic enhancement effect of fluorine on carbonbased materials also includes the prevent oxidation and the layer peeling,and realizes the precise atomic control.And the catalytic improvement mechanism of fluorine containing metal-based compounds also includes the hydration of metal site,the crystal transformation,and the oxygen vacancy induction.Then,based on their various dimensions(0D–3D),we also have summarized the advantages of different morphologies on oxygen electrocatalytic performances.Finally,the prospects and possible future researching direction of F-containing oxygen electrocatalysts are presented(e.g.,novel pathways,advanced methods for measurement and simulation,field assistance and multi-functions).The review is considered valuable and helpful in exploring the novel designs and mechanism analyses of advanced fluorine-containing electrocatalysts.

Structural design and modal behaviors analysis of a new swept baffled inflatable wing

Inflatable wing has significant application value in the design of loitering munitions because of its advantages such as lightweight and foldability.However,due to the flexible characteristics,aeroelastic behaviors of inflatable wings such as flutter are nonnegligible in flight.By designing a certain angle between the inflatable beam and the wing span,the structural dynamic and even the aeroelastic performance of the inflatable wing can be effectively improved.Based on the analysis of the mechanical and geometric characteristics of the inflatable structure,a new inflatable wing with sweep arranged inflatable beams is proposed,and the main design variables and methods are analyzed.For purpose of investigating the aeroelastic performance of the swept baffled inflatable wing,the modal behaviors by considering the wet mode are studied.In consideration of the deficiencies of the traditional wet modal analysis method,by introducing the influence on the additional stiffness of flow field,an added massstiffness method is proposed in this paper,and the advantages are verified by ground vibration experiments.On this basis,the effects of baffles sweep angle,pressure,and boundary conditions on the modal parameters and aeroelastic performance of inflatable wing are analyzed.The results show that the aeroelastic performance of the inflatable wing can be designed by changing the baffles sweep angle,which is enlightened for the aeroelastic tailoring design on inflatable wings.

Element doping induced microstructural engineering enhancing the lithium storage performance of high-nickel layered cathodes

The high-nickel layered cathodes Li[Ni_(x)Co_(y)Mn_(1-x-y)]O_(2)(x≥0.8)with high specific capacity and long cycle life are considered as prospective cathodes for lithium-ion batteries.However,the microcrack formation and poor structural stability give rise to inferior rate performance and undesirable cycling life.Herein,we propose a dual modification strategy combining primary particle structure design and element doping to modify Li[Ni_(0.95)Co_(0.025)Mn_(0.025)]O_(2) cathode by tungsten and fluorine co-doped(W-F-NCM95).The doping of W can convert the microstructure of primary particles to the unique rod-like shape,which is beneficial to enhance the reversibility of phase transition and alleviate the generation of microcracks.F doping is conducive to alleviating the surface side reactions.Thus,due to the synergistic effect of W,F codoping,the obtained W-F-NCM95 cathodes deliver a high initial capacity of 236.1 mA h g^(-1) at 0.1 C and superior capacity retention of 88.7%over 100 cycles at 0.5 C.Moreover,the capacity still maintains73.8%after 500 cycles at 0.5 C and the texture of primary particle is intact.This work provides an available strategy by W and F co-doping to enhance the electrochemistry performance of high-nickel cathodes for practical application.

The Structural Responses of Columns under Various Loadings

This paper focuses on the seismic resistance of one-storied factories, which are commonly used in China due to their flexibility, low cost, and short construction period. With the increasing demand for construction materials, these factories play a vital role in meeting the demands of urbanization and infrastructure development. The seismic resistance of these factories is critical to ensure safety, and this paper presents research on this topic. The paper highlights the advantages of one-storied factories, such as low maintenance cost and seismic resistance, and emphasizes the importance of conducting research on their seismic resistance to ensure safety in construction projects.

Structural Design and Analysis of Small Flapping Wing Aircraft Based on the Crank Slider Mechanism

In this project,the miniaturization of the aircraft was realized under the premise of strong maneuverability,high concealability,and driving a certain load,and the flight mode and structural characteristics of birds were imitated.A small bionic flapping wing aircraft was built.The flapping of the wing was realized by the crank slider mechanism,and the sizes of each part were calculated according to the bionics formula.The wingspan was 360.37 mm,the body width was 22 mm,the body length was 300 mm,the wing area was 0.05 m^(2),the flapping amplitude was 71°.ADAMS software was used to simulate the dynamics of the designed aircraft,and the variation of flapping amplitude and angular velocity during the movement of the aircraft was obtained,which verified the feasibility of the mechanism.The prototype aircraft was made for flight test,and the designed bionic flapping wing aircraft achieved the expected effect.It provides a theoretical basis and data support for the design and manufacture of small flapping wing aircraft.

Design,preparation,application of advanced array structured materials and their action mechanism analyses for high performance lithium-sulfur batteries

Lithium-sulfur battery(LSB)has brought much attention and concern because of high theoretical specific capacity and energy density as one of main competitors for next-generation energy storage systems.The widely commercial application and development of LSB is mainly hindered by serious“shuttle effect”of lithium polysulfides(Li PSs),slow reaction kinetics,notorious lithium dendrites,etc.In various structures of LSB materials,array structured materials,possessing the composition of ordered micro units with the same or similar characteristics of each unit,present excellent application potential for various secondary cells due to some merits such as immobilization of active substances,high specific surface area,appropriate pore sizes,easy modification of functional material surface,accommodated huge volume change,enough facilitated transportation for electrons/lithium ions,and special functional groups strongly adsorbing Li PSs.Thus many novel array structured materials are applied to battery for tackling thorny problems mentioned above.In this review,recent progresses and developments on array structured materials applied in LSBs including preparation ways,collaborative structural designs based on array structures,and action mechanism analyses in improving electrochemical performance and safety are summarized.Meanwhile,we also have detailed discussion for array structured materials in LSBs and constructed the structure-function relationships between array structured materials and battery performances.Lastly,some directions and prospects about preparation ways,functional modifications,and practical applications of array structured materials in LSBs are generalized.We hope the review can attract more researchers'attention and bring more studying on array structured materials for other secondary batteries including LSB.

An origami shield with supporting frame structures optimized by a feature-driven topology optimization method

In this paper,the design,manufacture and testing of an origami protective shield with a supporting frame structure are presented.It consists of an origami shield surface and a deployable supporting frame structure that needs to be portable and sufficiently stiff.First,for the design of the shield surface,a threestage origami crease pattern is developed to reduce the shield size in the folded state.The shield surface consists of several stiff modular panels and layered with flexible fabric.The modular panels are made of a multi-layer composite where a ceramic layer is made of small pieces to improve durability as those small pieces enable restriction of crack propagation.Then,the supporting frame structure is designed as a chain-of-bars structure in order to fold into a highly compact state as a bundle of bars and deploy in sequence.Thus,a feature-driven topology structural optimization method preserving component sequence is developed where the inter-dependence of sub-structures is taken into account.A bar with semi-circular ends is used as a basic design feature.The positions of the bar’s end points are treated as design variables and the width of the bars is kept constant.Then,a constraint on the total length of the chain of bars is introduced.Finally,the modular panels made of multi-layer composite and the full-scale prototype of the origami shield are fabricated and tested to verify the bullet-proof performance.

Study of the Ballistic Impact Behavior of Protective Multi-Layer Composite Armor

The abalone shell,a composite material whose cross-section is composed of inorganic and organic layers,has high strength and toughness.Inspired by the abalone shell,several multi-layer composite plates with different layer sequences and thicknesses are studied as bullet-proof material in this paper.To investigate the ballistic performance of this multi-layer structure,the complete characterization model and related material parameters of large deformation,failure and fracture ofAl_(2)O_(3)ceramics andCarbon Fiber Reinforced Polymer(CFRP)are studied.Then,3D finite element models of the proposed composite plates with different layer sequences and thicknesses impacted by a 12.7 mm armor-piercing incendiary(API)are built using Abaqus to predict failure.The simulation results show that the CFRP/Al2O3 ceramic/Ultrahigh Molecular Weight Polyethylene(UHMWPE)/CFRP(1 mm/4 mm/4 mm/1 mm)composite is the optimized stack of layers.The simulation results under specified layer sequence and thickness have a reasonable correlation with the experimental results and reflect the failure and fracture of the multi-layer composite protective armor.

Design and optimization of fluid lubricated bearings operated with extreme working performances——a comprehensive review

Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.

Resistive switching behavior and mechanism of HfO_(x) films with large on/off ratio by structure design

Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.

A systematic review of rigid-flexible composite pavement

Rigid-flexible composite pavement has gained significant popularity in recent decades.This paper provides a comprehensive review of the research progress concerning rigid-flexible composite pavement,aiming to promote its application and address key issues while identifying future directions.The design theory and methodology of rigid-flexible composite pavement are discussed,followed by a description of its structural and mechanical behavior characteristics.The load stress,temperature stress,and their interactive effects between the asphalt layer and the rigid base were analyzed.It is clarified that the asphalt layer serves a dual role as both a“functional layer”and a“structural layer”.Typical distresses of rigid-flexible composite pavement,which primarily occur in the asphalt layer,were discussed.These distresses include reflective cracking,top-down cracking,rutting,and compressive-shear failure.Generally,the integrity of the rigid base and the interlaminar bonding conditions significantly impact the performance and distress of the asphalt layer.The technology for enhancing the performance of rigid-flexible composite pavement is summarized in three aspects:asphalt layer properties,rigid base integrity,and interlaminar bonding condition.The study concludes that developing high-performance pavement materials based on their structural behaviors is an effective approach to improve the performance and durability of rigid-flexible composite pavement.The integrated design of structure and materials represents the future direction of road design.

Design and Engineering of Urban Interchange Ramp Bridge Structure

This paper analyzes the structural design of an urban interchange ramp bridge from four aspects,which are the superstructure,pier structure,foundation structure,and deck structure design to summarize the structural design ideas of this urban interchange ramp bridge,which can be used as a reference for future construction of the same bridge.

Design of Silkworm Cocoon Picking Mechanical System Based on ADAMS

This project to state cocoon to pick up object,by studying the cocoon stress performance and structure characteristics.On the basis of the picking up work process,vig virtual prototype technology to design and study a kind of mechanical used to cocoon picking,by using ADAMS,Soliworks software to complete the whole process of mechanical system design,simulation,can meet the premise of stable,reliable cocoon picking,and cocoon picking mechanical system design,low cost and simple structure.

Application Strategy of Composite Steel Composite Beams in Bridge Design

The combined prefabricated steel-hybrid stacked girder structure is very common in modern bridge design.An actual bridge engineering design project is taken as an example in this paper to analyze the application strategy of this structure,encompassing overall design strategy,structural design strategy,and structural calculation strategy.The aim is to offer insights that can enhance the quality of bridge design.

Research on the Course of Principles of Concrete Structure Design

Nowadays,education and teaching have become a hot topic,and teaching in colleges and universities is facing a brand-new development direction.Principles of Concrete Structure Design,as one of the main courses,transmits professional knowledge for students,enhances the students’professional ability,and further carries out in-depth research on the course to bring a better teaching effect for students.The article mainly focuses on the research of the principles of concrete structure design course,conducts an analysis of the teaching characteristics of the principles of concrete structure design course,and reasonably sets the teaching content from the optimization of the course teaching objectives;innovative course teaching methods can deepen the effect of knowledge understanding;reform of experimental practice teaching can lay down the effect of the internalization of knowledge,etc.The in-depth description and discussion of the relevant aspects of the research aim to provide guidelines for related research.

Application Strategies of Modular Design in Assembled Teaching Buildings

As an efficient,environmentally friendly,energy-saving construction method,assembled buildings are now widely used in campus building construction.Modular design thinking is system-based design thinking,and its application to the design of an assembled teaching building project will comprehensively improve the rationality of the teaching building and component design.The paper focuses on the application of modular design thinking in assembled teaching building design,aiming to provide references for China’s architectural design units,giving full play to the advantages of modular design thinking in future teaching building design projects,and enhancing the level of design,for the construction of the teaching building and the basis of the technical guarantee.

Structural Design Strategies of Polymer Matrix Composites for Electromagnetic Interference Shielding:A Review

With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.

Data-Driven Structural Design Optimization for Petal-Shaped Auxetics Using Isogeometric Analysis

Focusing on the structural optimization of auxetic materials using data-driven methods,a back-propagation neural network(BPNN)based design framework is developed for petal-shaped auxetics using isogeometric analysis.Adopting a NURBSbased parametric modelling scheme with a small number of design variables,the highly nonlinear relation between the input geometry variables and the effective material properties is obtained using BPNN-based fitting method,and demonstrated in this work to give high accuracy and efficiency.Such BPNN-based fitting functions also enable an easy analytical sensitivity analysis,in contrast to the generally complex procedures of typical shape and size sensitivity approaches.