Transfer characteristics of dynamic biochemical signals in non-reversing pulsatile flows in a shallow Y-shaped microfluidic channel: signal filtering and nonlinear amplitude-frequency modulation

The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts as a low-pass filter, and the biochemical signals are nonlinearly modulated by the pulsatile flows, which depend on the biochemical signal frequency, the flow signal frequency, and the biochemical signal transporting distance. It is concluded that, the transfer characteristics of the dynamic biochemical signals, which are transported in the time-varying flows, should be carefully considered for better loading biochemical signals on the cells cultured on the bottom of the microfluidic channel.

Johnson-Cook dynamic constitutive relationship for TC16 titanium alloy

The true stress-strain curves of TC16 alloy with a wide range of strain rates were investigated under uniaxial quasi-static tension and uniaxial dynamic compression with the Instron 8032 test machine and the split Hopkinson bar respectively. The results indicate that the true stress increases with increasing strain rate,while decreases with increasing temperature. Under the 105 s-1 high strain rate and temperature higher than 673 K,the true stress would even be less than that under quasi-static condition. A new method incorporating TC16's stress-strain curve developing item was proposed to determine the coefficients in J-C model easily and to avoid the estimation of the adiabatic temperature rising. The Johnson-Cook dynamic constitutive relationship for TC16 was obtained for the first time. Good agreement was obtained between the model prediction and the experimental stress-strain curves for TC16 under both quasi-static and dynamic loadings.

A review of extractive distillation from an azeotropic phenomenon for dynamic control

Extractive distillation is an effective method for separating azeotropic or close boiling point mixtures by adding a third component.Various technologies for performing the extractive distillation process have been explored to protect the environment and save resources.This paper focuses on the improvement of these advanced technologies in recent years.Extractive distillation is retrieved and analyzed from the view of phase equilibrium,selection of solvent in extractive distillation,process design,energy conservation,and dynamic control.The quantitative structure–property relationship used in extractive distillation is discussed,and the future development of extractive distillation is proposed to determine how the solvent affects the relative volatility of the separated mixture.In the steady state design,the relationship between the curvature of the residue curve and parameters of the optimal steady state is also highlighted as another field worthy of further study to simplify the distillation process.

A Train-Bridge Dynamic Interaction Analysis Method and Its Experimental Validation

The train-bridge dynamic interaction problem began with the development of railway technology, and requires an evaluation method for bridge design in order to ensure the safety and stability of the bridge and the running train. This problem is studied using theoretical analysis, numerical simulation, and experimental study. In the train-bridge dynamic interaction system proposed in this paper, the train vehicle model is established by the rigid-body dynamics method, the bridge model is established by the finite element method, and the wheel/rail vertical and lateral interaction are simulated by the corresponding assumption and the Kalker linear creep theory, respectively. Track irregularity, structure deformation, wind load, collision load, structural damage, foundation scouring, and earthquake action are regarded as the excitation for the system. The train-bridge dynamic interaction system is solved by inter-history iteration. A case study of the dynamic response of a CRH380BL high-speed train running through a standard-design bridge in China is discussed. The dynamic responses of the vehicle and of the bridge subsystems are obtained for speeds ranging from 200 km-b-1 to 400 km.h-1, and the vibration mechanism are analyzed.

Experimental investigation on static and dynamic resilient moduli of compacted fine soil

To investigate the static and dynamic resilient modulus of fine soil,and adapting to the new design code and maintenance system of highway subgrade in China,a series of static and dynamic tests were carried out according to the standard laboratory test methods(JTG E40-2007 and JTG D30-2015,respectively).The effects of initial water content,compactness and freeze-thaw cycles on the static and dynamic resilient moduli of fine soil were investigated and analyzed.Experimental test results show that with increasing water content,dry density and freeze-thaw cycles,the static moduli reduces about10.2%~40.0%,14.4%~45.5%,and 24.0%~50.3%,and dynamic moduli reduces about 10.9%~90.8%,2.5%~38.4%,and0.0%~46.0%,respectively.Then,the empirical mathematical relationship between static and dynamic resilient moduli was established under different water content,dry density and freeze-thaw cycles.The investigation results can be used to determine the dynamic modulus of fine soil by widely used static modulus,which could meet the requirement of adopting dynamic modulus index in new specification.

Design and Dynamic Analysis of the Recirculating Planetary Roller Screw Mechanism

The recirculating planetary roller screw mechanism(RPRSM)is a transmission mechanism that engages the screw and nut threaded by multiple grooved rollers.In this paper,frstly,the design method of RPRSM nut threadless area is proposed,and the equations related to the structural parameters of nut threadless area are derived.On this basis,the cross-section design method of roller,screw and nut is constructed according to the actual situation of engagements between the screw/nut and the roller.By adjusting the gap between the two beveled edges and that between the arc and the beveled edge,the accuracy of the thread engagements between the screw/nut and the roller can be improved.Secondly,to ensure the engagements of the screw/nut and the roller,the distance equation from the center surface of the diferent rollers to the end surface of cam ring is given.Thirdly,combined with the working principle and structural composition of RPRSM,the component model is established according to its relevant structural parameters,and the virtual assembly is completed.Finally,the 3D model is imported into the ADAMS simulation software for multi-rigid body dynamics.The dynamic characteristic is analyzed,and the simulated values are compared with the theoretical values.The results show that the contact forces between the screw/nut and the roller are sinusoidal,mainly due to the existence of a small gap between the roller and the carrier.The maximum collision forces between the roller and cam ring are independent from load magnitude.Normally,the collision force between the roller and the carrier increases as the load increases.When RPRSM is in the transmission process,the roller angular speed in nut threadless area begins to appear abruptly,and the position of the maximum change is at the contact between the roller and the convex platform of cam ring.The design of the nut threadless area and the proposed virtual assembly method can provide a theoretical guidance for RPRSM research,as well as a reference for overall performance optimization.

Study on the Dynamic Behavior of Tungsten Alloy at Strain Rates up to 5 000 s^(-1)

The dynamic stress-strain curves of 93% tungsten (W) alloy in the forged state at strain rates up to (5 000 s^(-1)) and in the temperature range from 223 K to 473 K were measured with the split Hopkinson pressure bar (SHPB) technique. Based on the above experimental data a dynamic constitutive equation considering the effects of strain rate, temperature and the special microstructure of such a kind of W-alloy was proposed. The numerical simulation for the experimental process with this constitutive equation was also carried out, the results show that the constitutive relationship constructed in this paper is very satisfactory for representing the dynamic responsive behavior of material..

Dynamic trend analysis on relational effect of environmental protection industry in China

EPI （environmental protection indastry） and three industries constitute aur national economic structuse. By Grey System Theory and correlation effect analytical method for the first time, this paper analyzes the relatioaship degree between environmental protection industry and the three causes including industries involved in China in both qualitative and quantitotive aspects. Both the innate tale and the realistic reasons nf the relational degree are further analyzed by utilizing sastninoble development theory, circulating economy theol., ecological equilibrium theory, externality theory. industrial structure theory, and ecology prinrity rules. From all the analysts, this paper reveals the relationship between EPI and three industries. In addition, it offers suggestions to the feasibility of adjusting the industrial structure and developing the environmental protection industry in our country.

数字金融与区域经济发展的耦合协调性测度及其动态演进

以中国八大综合经济区为例,运用耦合协调度模型分析数字金融对区域经济发展的耦合协调关系,并基于Dagum基尼系数与Kernel核密度揭示数字金融与区域经济发展之间协调关系的地区差异及动态演进规律。结果表明:八大综合经济区的经济发展水平总体呈现稳定增长态势,具有“东高西低”阶梯形的异质性和阶段性特征;数字金融与区域经济发展之间协调发展水平逐年提升,八大综合经济区普遍由失调阶段跨入协调阶段;数字金融与区域经济发展之间协调关系存在明显的地区差异,沿海经济区的协调水平明显高于内陆经济区,但地区间协调程度的差距呈现逐渐缩小的演进态势。

浮动基多机悬吊系统动力耦合响应分析

为了研究浮动基多机悬吊系统在不规则波作用下的动力耦合关系,首先利用动量定理和动量矩定理建立了浮动基机器人动力学模型,其次利用达朗贝尔原理建立了悬吊系统的动力学模型,并提出了系统动力学的耦合关系分析步骤;最后结合实例,仿真分析了浮动基多机器人协调悬吊系统在不同波高、不同波长比和不同起吊速度下动力耦合响应过程。结果表明,该系统的理论研究进行了补充和完善,同时也为浮动基多机悬吊系统在实际的吊运过程中,判断安全的吊运环境提供技术支撑。

循环荷载下渭北地区黄土动力特性分析

为研究渭北地区的黄土动力学特性分析,通过TYS-20型土动三轴试验机,研究不同围压下黄土的动本构关系以及动骨干曲线,分析黄土的动剪模量比和阻尼比的关系,提出动剪切模量衰减模型和阻尼增长模型;研究不同围压对黄土动强度和残余应变的影响,从理论上解释黄土动力特性变化的原因,从而更好地保证黄土震陷对地下空间影响最小化;最后对比黄土震前震后微结构,并进行机理分析对该地区地下空间发展提供理论意义.研究结果显示:黄土的动本构关系符合双曲线模型;动剪模量比随动剪应变呈负指数衰减关系,而阻尼比随动剪应变呈对数关系增长;动强度和动强度指标受试验条件的影响较大,其中动强度随围压的增大而增大,表明动强度分析能较好地说明黄土的动力特性变化规律;根据电子显微镜对比土体震前震后微结构,并进行机理分析,为该地区地下空间发展提供理论支持.通过研究表明,渭北地区黄土在循环荷载作用下不易产生振动变形,属于轻微震陷区.

低出生率背景下省域学前教育资源供需关系与动态调配——基于对中部J省人口预测的分析

低出生率背景下研判省域学前教育资源供需关系的变化,对优化学前教育资源配置、实现学前教育优质均衡发展具有指导意义。本研究选择省域学前教育资源配置中低供给高需求类型的中部J省作为研究对象,运用PADIS-INT软件预测分析了J省2023—2035年低、中、高三种方案下城乡在园幼儿人数的变化,调查了J省学前教育人力资源与物力资源供给现状,进而预测分析了J省学前教育资源在供给动态变化与静态不变情况下的供需关系。结果发现,随着在园幼儿人数减少,学前教育资源需求将明显减少;现有人力资源供给存在结构性短缺,未来会出现城乡配置失衡;物力资源配备已达到高水平,未来会严重过剩。根据研究结果,建议地方政府根据资源供需关系的动态变化做好学前教育长期规划,控增量、调存量、疏余量;从结构与质量入手优化人力资源配置,稳定乡村教师队伍;谨慎增加办园条件投入,采用多种形式提升物力资源使用效益。

生育水平与女性劳动参与率的动态关系研究

生育水平变动会影响未来劳动年龄人口供给,但生育水平与女性劳动参与率的相关性研究结论尚有争议。基于我国1970—2021年生育率水平和女性劳动参与率时间序列数据,通过平稳性检验、协整检验以及格兰杰因果检验后,建立向量自回归(VAR)模型对两者之间的变动关系进行实证分析和检验,从宏观角度揭示生育水平变动与女性劳动参与率变化的动态关联性。研究发现,我国生育水平与女性劳动参与率的相关性由1979—1990年的负相关转变为1991—2021年的正相关,生育水平与女性劳动参与率存在长期稳定的均衡关系,总和生育率与女性劳动参与率已总体呈现出一定的格兰杰因果关系;1991—2021年我国总和生育率与女性劳动参与率的互动响应关系显著,女性劳动参与率变动对总和生育率变动的冲击影响呈现滞后性,且影响程度没有总和生育率对女性劳动参与率的冲击影响大。因此,在生育政策调整背景下,我国应充分重视生育水平与女性劳动参与率的互动影响和冲击响应关系,有效保障女性生育和劳动权益,推进性别平等的生育支持体系建设,在提振社会生育水平的同时稳定女性劳动参与率。

Vegetation-Climate Relationship and Its Application in the Division of Vegetation Zone in China

Distribution of vegetation is closely coupled with climate; the climate controls distribution of vegetation and the vegetation type reflects regional climates. To reveal vegetation_climate relationships is the foundation for understanding the vegetation distribution and theoretically serving vegetation regionalization. Vegetation regionalization is a theoretical integration of vegetation studies and provides a base for physiogeographical regionalization as well as agriculture and forestry regionalization. Based on a brief historical overview on studies of vegetation_climate relationships and vegetation regionalization conducted in China, we review the principles, bases and major schemes of previous vegetation regionalization and discuss on several contentious boundaries of vegetation zones in the present paper. We proposed that, under the circumstances that the primary vegetation has been destroyed in most parts of China, the division of vegetation zones/regions should be based on the distribution of primary and its secondary vegetation types and climatic indices that delimit distribution of the vegetation types. This not only reveals the closed relationship between vegetation and climate, but also is feasible practically. Although there still are divergence of views on the name and their boundaries of the several vegetation zones, it is commonly accepted that there are eight major vegetation regions in China, i.e. cold temperate needleleaf forest region, temperate needleleaf and broadleaf mixed forest region, warm temperate deciduous broadleaf forest region, subtropical evergreen broadleaf forest region, tropical monsoon forest and rain forest region, temperate steppe region, temperate desert region, and Qinghai_Xizang (Tibetan) Plateau high_cold vegetation region. Analyzing characteristics of vegetation and climate of major vegetation boundaries, we suggested that: 1) Qinling Mountain_Huaihe River line is an important arid/humid climatic, but not a thermal climatic boundary, and thus can not also be regarded as the northern limit of the subtropical vegetation zone; 2) the northern limit of subtropical vegetation zone in China is along the northern coast of the Yangtze River, from Hangzhou Bay, via Taihu Lake, Xuancheng and Tongling in Anhui Province, through by southern slope of the Dabie Mountains, to Wuhan and its west, coinciding with a warmth index ( WI ) value of 130-140 ℃·month; 3) the tropical region is limited in a very small area in southeastern Hainan Island and southern edge of Taiwan Island; and 4) considering a significant difference in climates between the southern and northern parts of the warm temperate zone, we suggested that the warm temperate zone in China is divided into two vegetation regions, deciduous broadleaf woodland region and deciduous and evergreen broadleaf mixed forest region, the Qinling Mountain_Huaihe River line being as their boundary. We also claimed that the zonal vegetation in North China is deciduous broadleaf woodland. Finally, we emphasized the importance of dynamic vegetation regionalization linked to climate changes.

岩石爆破基础理论研究进展与展望Ⅱ—动静关系

炸药爆炸做功与岩体破碎耗能的耦合作用机理、炸药能量释放与爆炸裂纹扩展的精细控制原理,是岩石爆破基础理论需要解决的两个关键科学问题;“动静关系”研究是解决关键科学问题的重要途径之一.本文采用文献综述分析方法对2000年—2023年期间在中国知网数据库(CNKI)和科学引文索引数据库(WOS)收录的期刊论文进行了主题检索和分析,将岩石爆破“动静关系”研究划分为三个不同阶段:第Ⅰ阶段(2006年之前)、第Ⅱ阶段(2007年—2015年)和第Ⅲ阶段(2016年至今).确定了对“动静关系”研究有重要贡献的作者和研究机构,揭示了关键词及其共现关系,突出了研究的重点和趋势.通过对已有研究的系统梳理,结合作者团队已经开展的研究工作和成果,明确了新时期“动静关系”的研究方向,即爆炸应力波与爆生气体的动静能量分布与高效利用、考虑岩石爆破破裂真实物理过程的数值模拟算法、爆炸应力波与爆生气体动静破岩效果的量化调控.“动静关系”的深入研究将推动爆破工程从“经验主导”走向“理论指导”,从“粗放式”走向“精细化”.

动态化学交联聚烯烃类弹性体研究进展

聚烯烃类弹性体是由乙烯与丙烯或其他高碳α-烯烃共聚而成的高端聚烯烃材料,具有出色的化学稳定性、耐候性和电绝缘性,广泛应用于光伏、汽车、电缆等领域。通过动态化学交联可在保证其加工性的前提下,进一步提高其力学性能与热稳定性,拓展应用范围。综述了动态化学交联聚烯烃弹性体的制备工艺,包括一步法直接交联和功能化后再交联(多步法)。详细介绍了后功能化、乙烯与功能化单体共聚等功能化方法。讨论了动态化学交联聚烯烃类弹性体的表征手段及其链结构、聚集态结构和性能之间的关系。展望了动态交联聚烯烃类弹性体的未来发展。为动态化学交联聚烯烃类弹性体的可控制备、构效关系研究以及高值应用提供理论指导与技术支持,推动高端聚烯烃材料的创新和发展。

等效锥度非线性研究及其在踏面设计中的应用

为研究等效锥度非线性特性对车辆系统动力学和磨耗性能的影响,提出可以用于踏面优化设计的非线性特性建议指标。通过对轮轨关系进行细致推导,应用踏面逆向设计快速递推算法,得到具有不同等效锥度非线性特性的踏面,对不同踏面的轮轨关系进行分析。建立车辆系统动力学模型和基于Archard理论的磨耗预测模型,对不同非线性特性踏面的临界速度、横向平稳性、磨耗性能进行对比分析。研究结果表明:非线性因子值过高或过低都会导致临界速度下降,但该指标过高对临界速度影响更大,最大降幅可达20%;等效锥度非线性特性还会影响到踏面的磨耗发展,踏面的初始非线性因子越高,名义等效锥度在磨耗过程中的增长越慢,对延长车轮服役周期是有利的。综合动力学性能及磨耗性能,建议高速列车踏面的非线性因子应取尽可能接近于0的负值。在这一结论的指导下,对S1002CN踏面进行优化设计,得到名义等效锥度为0.1,等效锥度非线性因子为0.013(与S1002CN持平)、-0.002的优化踏面S1002CN_opt1、S1002CN_opt2,优化踏面S1002CN_opt2与S1002CN相比临界速度和横向平稳性有所优化,同时磨耗性能也有所提升。S1002CN_opt2与S1002CN_opt1之间的等效锥度非线性关系在动力学性能及磨耗性能中的表现证明以等效锥度非线性因子限值指导踏面进行优化设计的可行性,研究结果可为踏面设计及轮轨关系研究提供参考。

西北季节性冻土场地地震反应特性研究

我国西北地区被季节冻土全覆盖,且近年来该区域地震频发。为研究我国西北地区季节性冻土场地的地震反应特性,开展了季节性冻土场地振动台试验,并建立了不同冻结深度的三维实体有限差分模型,对比分析了不同地震激励作用下的季节性冻土场地的地震反应特征和土体的动剪应力—动剪应变规律。结果表明:在地震激励下,冻土层的存在虽然有效抑制了地震动能量,但冻结期场地的水平位移与非冻结期相比明显较大,且竖向位移呈显著的层状震陷特征;冻土场地的峰值放大系数呈先增大后减小然后再增大的规律,并且冻土层深度越大其峰值放大系数越小。此外,通过土体的动剪应力—动剪应变关系可以发现,冻土场地地震反应具有明显的非线性特征,且冻土层的存在对地震能量具有一定的削弱作用。

两类混凝土动力黏损伤本构模型比较研究

在混凝土弹塑性损伤理论框架下,为反映材料力学行为的率相关性,对静力损伤演化进行了动力扩展。混凝土在动力加载下的损伤演化滞后于静力加载而引起强化现象,借鉴黏塑性理论,在损伤子空间建立了两类格式的动力黏损伤演化模型:Perzyna模型和Duvaut-Lions模型。分别从本构理论和数值计算结果上对两类黏损伤演化模型进行了对比研究。从理论上来看,两类模型具有不同的黏性化变量;从模拟结果上来看,两类格式的线性黏损伤模型的计算结果基本重合,而两类非线性的黏损伤模型得到的结果存在差异。另外,两类非线性的黏损伤模型预测的混凝土动力强度的提高与试验数据吻合较好,说明均可反映混凝土材料的率相关性。

炮口振动特性对自动炮射击精度的影响研究

为研究炮口振动特性对射击精度的影响,以某型自动炮为研究对象,对模型做出合理假设,分析自动炮系统各部件之间的约束关系,基于火炮发射多体动力学理论,考虑身管柔性、机构间隙等因素,建立了自动炮动力学仿真模型;通过火炮水平射击时后坐和复进的后坐力及后坐位移曲线,验证了仿真模型的准确性。对单发和连发射击时的自动炮动力学特性仿真模型进行仿真计算,得到了该自动炮单发及连发射击时的炮口动态特性。根据各发弹丸出炮口瞬间炮口振动特性,初步计算了千米立靶密集度。仿真结果及立靶密集度计算结果对火炮射击精度的提高和结构优化具有一定的参考价值。