Numerical Prediction of Ride Comfort of Tracked Vehicle Equipped with Novel Flexible Road Wheels

Enhancing ride comfort has always constituted a crucial focus in the design and research of modern tracked vehicles,heavily reliant on the driving system's performance.While the road wheel is a key component of the driving system,traditional road wheels predominantly adopt a solid structure,exhibiting subpar adhesion performance and damping effects,thereby falling short of meeting the demands for high-speed,stable,and long-distance driving in tracked vehicles.Addressing this issue,this paper proposes a novel type of flexible road wheel(FRW)characterized by a catenary construction.The study investigates the ride comfort of tracked vehicles equipped with flexible road wheels by integrating finite element and vehicle dynamic.First,three-dimensional(3D)finite element(FE)models of both flexible and rigid road wheels are established,considering material and contact nonlinearities.These models are validated through a wheel radial loading test.Based on the validated FE model,the paper uncovers the relationship between load and radial deformation of the road wheel,forming the basis for a nonlinear mathematical model.Subsequently,a half-car model of a tracked vehicle with seven degrees of freedom is established using Newton's second law.A random road model,considering the track effect and employing white noise,is constructed.The study concludes by examining the ride comfort of tracked vehicles equipped with flexible and rigid road wheels under various speeds and road grades.The results demonstrate that,in comparison to the rigid road wheel(RRW),the flexible road wheel enhances the ride comfort of tracked vehicles on randomly uneven roads.This research provides a theoretical foundation for the implementation of flexible road wheels in tracked vehicles.

Controlled Twill Surface Structure Endowing Nanofiber Composite Membrane Excellent Electromagnetic Interference Shielding

Inspired by the Chinese Knotting weave structure,an electromagnetic interference(EMI)nanofiber composite membrane with a twill surface was prepared.Poly(vinyl alcohol-co-ethylene)(Pva-co-PE)nanofibers and twill nylon fabric were used as the matrix and filter templates,respectively.A Pva-co-PEMXene/silver nanowire(Pva-co-PE-MXene/AgNW,PM_(x)Ag)membrane was successfully prepared using a template method.When the MXene/AgNW content was only 7.4 wt%(PM_(7.4)Ag),the EMI shielding efficiency(SE)of the composite membrane with the oblique twill structure on the surface was 103.9 dB and the surface twill structure improved the EMI by 38.5%.This result was attributed to the pre-interference of the oblique twill structure in the direction of the incident EM wave,which enhanced the probability of the electromagnetic waves randomly colliding with the MXene nanosheets.Simultaneously,the internal reflection and ohmic and resonance losses were enhanced.The PM_(7.4)Ag membrane with the twill structure exhibited both an outstanding tensile strength of 22.8 MPa and EMI SE/t of 3925.2 dB cm^(-1).Moreover,the PM_(x)Ag nanocomposite membranes demonstrated an excellent thermal management performance,hydrophobicity,non-flammability,and performance stability,which was demonstrated by an EMI SE of 97.3%in a high-temperature environment of 140℃.The successful preparation of surface-twill composite membranes makes it difficult to achieve both a low filler content and a high EMI SE in electromagnetic shielding materials.This strategy provides a new approach for preparing thin membranes with excellent EMI properties.

Advancing the pressure sensing performance of conductive CNT/PDMS composite film by constructing a hierarchical-structured surface

Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine interaction.However,the tradeoff between their high sensitivity and wide response range remains a challenge.Inspired by human skin,we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube(CNT)/polydimethylsiloxane(PDMS)composite film with a hierarchical structured surface(h-CNT/PDMS)through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane(PU)scotch tape to obtain an h-CNT/PDMS-based flexible pressure sensor.Based on in-situ optical images and finite element analysis,the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range(0.1661 kPa^(-1),0.4574 kPa^(-1)and 0.0989 kPa^(-1)in the pressure range of 0–18 kPa,18–133 kPa and 133–300 kPa)compared with planar CNT/PDMS composite film(0.0066 kPa^(-1)in the pressure range of 0–240 kPa).The prepared pressure sensor displays rapid response/recovery time,excellent stability,durability,and stable response to different loading modes(bending and torsion).In addition,our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial distribution.This study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.

Determination of the Effect of Initial Inner-Core Structure on Tropical Cyclone Intensification and Track on a Beta Plane

The sensitivity of TC intensification and track to the initial inner-core structure on a β plane is investigated using a numerical model. The results show that the vortex with large inner-core winds（CVEX-EXP） experiences an earlier intensification than that with small inner-core winds（CCAVE-EXP）, but they have nearly the same intensification rate after spin-up. In the early stage, the convective cells associated with surface heat flux are mainly confined within the inner-core region in CVEXEXP, whereas the vortex in CCAVE-EXP exhibits a considerably asymmetric structure with most of the convective vortices being initiated to the northeast in the outer-core region due to the β effect. The large inner-core inertial stability in CVEX-EXP can prompt a high efficiency in the conversion from convective heating to kinetic energy. In addition, much stronger straining deformation and PBL imbalance in the inner-core region outside the primary eyewall ensue during the initial development stage in CVEX-EXP than in CCAVE-EXP, which is conducive to the rapid axisymmetrization and early intensification in CVEX-EXP. The TC track in CVEX-EXP sustains a northwestward displacement throughout the integration, whereas the TC in CCAVE-EXP undergoes a northeastward recurvature when the asymmetric structure is dominant. Due to the enhanced asymmetric convection to the northeast of the TC center in CCAVE-EXP, a pair of secondary gyres embedded within the large-scale primary β gyres forms, which modulates the ventilation flow and thus steers the TC to move northeastward.

A New Simulation of Track Structure of Low-Energy Electrons in Liquid Water:Considering the Condensed-Phase Effect on Electron Elastic Scattering

A new Monte Carlo simulation of the track structure of low-energy electrons （〈10keV） in liquid water is presented. The feature of the simulation is taken into consideration of the condensed-phase effect of liquid water on electron elastic scattering with the use of the Champion model, while the dielectric response formalism incorporating the optical-data model developed by Emfietzoglou et al. is applied for calculating the electron inelastic scattering. The spatial distributions of energy deposition and inelastic scattering events of low-energy electrons with different primary energies in liquid water are calculated and compared with other theoretical evaluations. The present work shows that the condensed-phase effect of liquid water on electron elastic scattering may be of the influence on the fraction of absorbed energy and distribution of inelastic scattering events at lower primary energies, which also indicate potential effects on the DNA damage induced by low-energy electrons.

Tailoring the Meso-Structure of Gold Nanoparticles in Keratin-Based Activated Carbon Toward High-Performance Flexible Sensor

Flexible biosensors with high accuracy and reliable operation in detecting pH and uric acid levels in body fluids are fabricated using well-engineered metaldoped porous carbon as electrode material.The gold nanoparticles@N-doped carbon in situ are prepared using wool keratin as both a novel carbon precursor and a stabilizer.The conducting electrode material is fabricated at 500℃ under customized parameters,which mimics A-B type(two different repeating units) polymeric material and displays excellent deprotonation performance(pH sensitivity).The obtained pH sensor exhibits high pH sensitivity of 57 mV/pH unit and insignificant relative standard deviation of 0.088%.Conversely,the composite carbon material with sp^2 structure prepared at 700℃ is doped with nitrogen and gold nanoparticles,which exhibits good conductivity and electrocatalytic activity for uric acid oxidation.The uric acid sensor has linear response over a range of 1-150 μM and a limit of detection 0.1 μM.These results will provide new avenues where biological material will be the best start,which can be useful to target contradictory applications through molecular engineering at mesoscale.

Comparison among the Consumption Structures of Different Income Groups of Urban Residents in Guangxi Based on ELES Model

According to the household consumption data of urban residents in Guangxi Statistical Yearbook in the year 2009, the ELES (Extended Linear Expenditure System) is used to analyze the consumption structure, the propensity to consume, and the consumer flexibility of urban residents in Guangxi Zhuang Autonomous Region of China in the year 2008. Result shows that urban residents in Guangxi has relatively low propensity to consume. And their consumption, especially the middle and low-income families, is mostly concentrated in food, cloth, lodging and other basic necessities of life, which account for more than a half of their income. Based on this, corresponding suggestions are put forward to enlarge the consumption demand of urban residents in Guangxi, such as increasing the regulation of income redistribution, minimizing the gap between the rich and the poor, enhancing the overall consumption level, cultivating the consumption hot spots for the urban residents, and actively guiding the enjoyable consumption.

Design method of pile-slab structure roadbed of ballastless track on soil subgrade

Pile-slab structure roadbed is a new form of ballastless track for high speed railway. Due to lack of corresponding design code, based on the analysis of its structure characteristics and application requirements, it is proposed to carry out load effect combination according to ultimate limit state and serviceability limit state, and the most unfavorable combination of each state is chosen to carry through design calculation for pile-slab structure. Space model of pile-slab structure can be simplified as a plane flame model, by using the orthogonal test method, and the design parameter of pile-slab structure is optimized. Moreover, based on the engineering background of Suining-Chongqing high-speed railway, the dynamic deformation characteristics of pile-slab structure roadbed are further researched by carrying on the indoor dynamic model test. The test results show that the settlement after construction of subgrade satisfies the requirement of settlement control to build ballastless track on soil subgrade for high-speed railway. Slab structure plays the role of arch shell as load is transmitted from slab to pile, and the vertical dynamic stress of subgrade soil is approximately of ＂K＂ form distribution with the depth. The distribution of pile stress is closely related to soil characteristics, which has an upset triangle shape where the large dynamic stress is at the top. Pile compared with soil shares most dynamic stress. Pile structure expands the depth of the dynamic response of subgrade has limited effect on dynamic response. These results can provide subgrade. and improves the stress of subgrade soil, and the speed of train scientific basis for pile-slab structure roadbed used on soil

Synthesis and Crystal Structure of a New Coordination Polymer:{[AgL]ClO_4}_n (L=2,5-Bis(3-pyridinylmethylthio)-1,3,4-thiadiazole)

The title complex {[AgL]ClO4}n（L=2,5-bis（3-pyridinylmethylthio）-1,3,4-thiadiazole） was synthesized by the reaction of Ag（I） salt and a novel flexible ligand L.Its structure was determined by X-ray crystallography with the following data：monoclinic,space group P21/n,a=16.5068（13）,b=7.6548（4）,c=16.5521（13）A,β=115.119（3）o,V=1893.7（2）A^3,Z=4,Dc=1.893 g/cm^3,μ=1.565 mm^-1,F（000）=1072,C14H12AgClN4O4S3,Mr=539.78,T=293（2） K,S=1.067,the final R=0.0342 and wR=0.0870.The silver ion in the complex is in a trigonal coordination geometry to link three different L.Meanwhile,each L connects three different silver ions by its N coordination sites to form a two-dimensional layer structure.

Influence of structure and material on the vibration modal characteristics of novel combined flexible road wheel

Aiming at the independent development of tracked vehicles,it is urgent to improve its mobility,passability and ride comfort,a new type of flexible road wheel with a“wheel-hinge-hub”combined structure is proposed in this study.The vibration model characteristics of the flexible road wheel were studied by the combination of numerical simulation and experiments.The superelasticity of rubber is obtained through uniaxial tensile experiment of the material and a detail three-dimensional nolinear finite element model of the flexible road wheel is established through finite element software ABAQUS.The free vibration equation of the flexible road wheel is solved by Lanczos vector direct superposition method,and its predicted modes and natural frequencies are compared with experimental results,which verifies the accuracy and reliability of the established finite element model.On this basis,the effects of various key structural or material factors on the natural frequencies of the flexible road wheel are studied using orthogonal experimental design method.Besides,the vibration modal characteristics of the flexible road wheel are also compared with those of the rigid road wheel.The research results provide a theoretical basis for the vibration and noise reduction of flexible road wheel.

THE STRUCTURE OF TROPICAL CYCLONE BY TOVS AND ITS APPLICATION IN NUMERICAL WEATHER PREDICTION

The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000. Differences are found to some extent between what is found and classic conceptual models in that (1) the horizontal structure is asymmetric and variable so that the low-value centers at low levels of the geopotential height field (or the high-value centers at high levels) do not necessarily coincide with the high-value centers of the temperature field; (2) the vertical structure is also variable in the allocation of the anomalies of the geopotential height field between low values at low levels and high values at high levels. It is especially noted that the centers of the anomalies are tilting at both high and low levels or the high level is only at the edge of a high-pressure zone. There is not any significant high-value anomalous center in a corresponding location with the tropical cyclone. The structure of tropical cyclone in the TOVS is also used as reference to modify the structure of typhoon BOGUS in the numerical prediction model system of tropical cyclones. It is found that the modified BOGUS performs better in coordinating with the environment and predicting the track of the tropical cyclone. The demonstration is two-fold the structure of the typhoon BOGUS is such that it means much in the track prediction and the use of the TOVS-based tropical cyclone structure really helps in improving it. It provides the foundation for modification and evolution of typhoon BOGUS.

Typhoon Track,Intensity,and Structure:From Theory to Prediction

To improve understanding of essential aspects that influence forecasting of tropical cyclones(TCs),the National Key Research and Development Program,Ministry of Science and Technology of the People's Republic of China conducted a five-year project titled“Key Dynamic and Thermodynamic Processes and Prediction for the Evolution of Typhoon Intensity and Structure”(KPPT).Through this project,new understandings of TC intensification,including outer rainbanddriven secondary eyewall formation and the roles of boundary layer dynamics and vertical wind shear,and improvements to TC data assimilation with integrated algorithms and adaptive localizations are achieved.To promote a breakthrough in TC intensity and structure forecasting,a new paradigm for TC evolution dynamics(i.e.,the correlations,interactions,and error propagation among the triangle of TC track,intensity,and structure)is proposed;and an era of dynamic-constrained,big-data driven,and strongly coupled data assimilation at the subkilometer scale and seamless prediction is expected.

Thermal-Fluid-Structure Coupling Analysis of Flexible Corrugated Cryogenic Hose

This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench.The flow transport behavior,heat transfer across the hose layers,and structural response caused by the flow are analyzed.Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose.The study found that,compared with a regular operating condition,higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress.The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface,showing little temperature change with respect to material thermal conductivity and ambient temperature.The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.

Fault Identification for Shear-Type Structures Using Low-Frequency Vibration Modes

Shear-type structures are common structural forms in industrial and civil buildings,such as concrete and steel frame structures.Fault diagnosis of shear-type structures is an important topic to ensure the normal use of structures.The main drawback of existing damage assessment methods is that they require accurate structural finite element models for damage assessment.However,for many shear-type structures,it is difficult to obtain accurate FEM.In order to avoid finite elementmodeling,amodel-freemethod for diagnosing shear structure defects is developed in this paper.This method only needs to measure a few low-order vibration modes of the structure.The proposed defect diagnosis method is divided into two stages.In the first stage,the location of defects in the structure is determined based on the difference between the virtual displacements derived from the dynamic flexibility matrices before and after damage.In the second stage,damage severity is evaluated based on an improved frequency sensitivity equation.Themain innovations of this method lie in two aspects.The first innovation is the development of a virtual displacement difference method for determining the location of damage in the shear structure.The second is to improve the existing frequency sensitivity equation to calculate the damage degree without constructing the finite elementmodel.Thismethod has been verified on a numerical example of a 22-story shear frame structure and an experimental example of a three-story steel shear structure.Based on numerical analysis and experimental data validation,it is shown that this method only needs to use the low-order modes of structural vibration to diagnose the defect location and damage degree,and does not require finite element modeling.The proposed method should be a very simple and practical defect diagnosis technique in engineering practice.

Synthesis,Crystal Structure and Properties of a Novel Decavanadate Complex with One-dimensional Chain Involving Sodium and 'Bis-tris' Ligand

By using a flexible multidentate ligand,bis（2-hydroxyethyl）iminotris（hydroxyhydroxylmethy）methane（＇bis-tris＇：H5L）,the title complex {[Na（H6L）2]2}n·nV10O28（1） has been successfully synthesized under self-assembly condition and characterized by IR spectroscopy,elemental analysis,PXRD and single-crystal X-ray diffraction.The crystal structure belongs to an orthorhombic system,space group Cmca with a = 23.752（2）,b = 13.5360（8）,c = 18.5377（11） ,V = 5960.1（7）,Z = 8,Dc = 2.055 g/cm3,F（000） = 3744,μ = 1.630 mm-1,the final R = 0.0283 and wR = 0.0759 for 3353 observed reflections with I 〉 2σ（I）.This complex consists of decavanadate [V10O28]6-motifs as counter anions intercalated with one-dimensiond chains of the composition [Na（H6L）2]n3n＋.And significant intermolecular O-H…O hydrogen-bonding interactions lead to a three-dimensional supramolecular framework.

Design and evaluation of UHPP steel bridge deck pavement for high-temperature and rainy regions

To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of a three-layer ultra-high-performance pavement(UHPP).The high-temperature rutting resistance and wet-weather skid resistance of UHPP were evaluated through composite structure tests.The internal temperature distribution within the pavement under typical high-temperature conditions was analyzed using a temperature field model.Additionally,a temperature-stress coupling model was employed to investigate the key load positions and stress response characteristics of the UHPP.The results indicate that compared with the traditional guss asphalt+stone mastic asphalt structure,the dynamic stability of the UHPP composite structure can be improved by up to 20.4%.Even under cyclic loading,UHPP still exhibits superior surface skid resistance compared to two traditional SBDPs.The thickness composition of UHPP significantly impacts its rutting resistance and skid resistance.UHPP exhibits relatively low tensile stress but higher shear stress levels,with the highest shear stress occurring between the UHPP and the steel plate.This suggests that the potential risk of damage for UHPP primarily lies within the interlayer of the pavement.Based on engineering examples,introducing interlayer gravel and optimizing the amount of bonding layer are advised to ensure that UHPP possesses sufficient interlayer shear resistance.

Syntheses and Crystal Structures of Three Cadmium（II） Coordination Complexes Based on Flexible 1,2-Bis（imidazol-1~ˊ-yl）ethane

Three Cd（II） coordination complexes,{[Cd（bime）3]（NO3）2·（H2O）3}n（1）,[Cd（bime）Br2]n（2） and [（H2bime）（CdBr4）（H2O）]n（3）（bime = 1,2-bis（imidazol-1-yl）ethane）,have been prepared and characterized.Single-crystal X-ray diffraction analysis reveals that 1~3 crystallize in the trigonal space group P-3,monoclinic space group C2/c and triclinic space group P1,respectively.In 1,bime bridges six-coordinated Cd（II） to generate a two-fold interpenetrating 3D coordination polymer,in which NO3- is not involved in coordination,but serves as a void filler to balance the charge of the 3D framework.The six NO3- and six uncoordinated water molecules form an unprecedented 24-membered macrocycle through hydrogen bonding interaction.In 2,bime in an anti-conformation links the CdBr2 units into a zigzag chain.In 3,bime does not take part in coordination,but is protonated to act as a counter cation of [CdBr4 ]2-.The hydrogen bonds between H2bime and [CdBr4]2- result in the formation of a supramolecular chain.

Integrated Optimal Model of Structure and Control of the Single Arm Manipulator

The integrated optimal design of mechanical and control system is discussed in terms of the performance requirement and configuration for the single arm flexible manipulator. By combination of dynamics of flexible structure and control theory, a PD feedback control system, which minimizes the settling time, has been designed. Then, the viable region of poles of the PD dosed-loop control system is decided according to overshoot and the settling time, and an integrated optimal model of structure and control of single arm manipulator is presented. Finally, the parameters of structure and control system are simultaneously optimized with respect to objective function induding the moment of inertia and the control effort of system.

Syntheses and Crystal Structures of Two One-dimensional Cobalt(Ⅱ) Compounds with the Flexible Dipyridyl Ligand

Two one-dimensional cobalt（II） compounds {[Co（Hbpma）（H20）4]2·3SO4·4.5H2O}n 1 and {[Co（Hbpma）（NCS）3（H20）]·2.85H2O}n 2 （bpma = N,N＇-bis（3-pyridylmethyl）amine） have been synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in triclinic, space group Pi with a = 15.8780（5）, b = 16.2187（5）, c = 16.4858（5） A, α = 91.0420（10）,β = 94.5190（10）, γ = 101.4360（10）°, V = 4145.7（2） A3, C24H53Co2N6024.5083, Mr = 1031.76, Z = 4, Dc = 1.653 g/cm3, p（MoKa） = 1.046 mm-1, F（000） = 2148, S = 1.017, the final R = 0.0269 and wR = 0.0644 for 13032 observed reflections （I 〉 2a（/））. For complex 2, it belongs to triclinic, space group Pi with a = 9.3761（11）, b = 10.5814（13）, c = 11.2972（14）A, α= 85.472（2）,β = 88.058（2）,γ = 76.203（2）°, V= 1085.0（2） A3, C15Hzl.v0CoN603.85S3, Mr= 502.79, Z = 2, Dc = 1.539 g/cm3, p（MoKa） = 1.112 mm-1, F（000） = 519, S = 1.070, the final R = 0.0358 and wR = 0.0899 for 3466 observed reflections （I 〉 2σ（I））. Two complexes 1 and 2 are both found to be one-dimensional coordination polymers bridged by the protonated bpma ligands, which are assembled into three-dimensional supramolecular structures through the hydrogen bonding interactions and π-π packing interactions.

Syntheses and Crystal Structures of Two Cadmium(Ⅱ) Compounds Linked by N,N-Bis(3-pyridylmethyl)amine

Two cadmium（Ⅱ） compounds linked by a flexible dipyridyl ligand {[Cd2（Hbpma） Cl5（H2O）]·2H2O}n 1 and [Cd（Hbpma）Cl（H2O）2]2·2SO4·3H2O 2 （bpma = N,N-bis（3-pyridylmethyl）amine） have been synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in triclinic, space group P with a = 9.5612（6）, b = 11.3401（7）, c = 11.5069（12）, α = 112.8540（10）, β = 106.5330（10）, γ = 101.6680（10）°, V = 1030.77（14）3, C12H20Cd2Cl5N3O3, Mr = 656.36, Z = 2, Dc = 2.115 g/cm3, μ（MoKα） = 2.727 mm–1, F（000） = 636, S = 1.059, the final R = 0.0319 and wR = 0.0822 for 3443 observed reflections （I 2σ（I））. For complex 2, it belongs to triclinic, space group P with a = 10.9487（4）, b = 11.4197（4）, c = 15.4288（5）, α = 94.7470（10）, β = 104.1000（10）, γ = 104.42°, V = 1790.76（11）3, C24H42Cd2Cl2N6O15S2, Mr = 1014.46, Z = 2, Dc = 1.881 g/cm3, μ（MoKα） = 1.529 mm–1, F（000） = 1020, S = 1.050, the final R = 0.0178 and wR = 0.0451 for 6026 observed reflections （I 2σ（I））. Complex 1 is found to have tetranuclear Cd（Ⅱ） clusters which are bridged by the protonated bpma ligands leading to one-dimensional coordination polymers, whereas complex 2 consists of binuclear Cd（Ⅱ） structures linked by the protonated bpma ligands. Both complexes are assembled into three-dimensional supramolecular structures through hydrogen bonding interactions.