Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials

Preisach model is widely used in modeling of smart materials. Although first order reversal curves （FORCs） have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards： （1） giving the reason a first order reversal curve is introduced; （2） presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution＇s uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to.

Induction of Forces at Distance Performed by Piezoelectric Materials

We describe the phenomenon of generation of an external field of forces from piezoelectric materials subjected to the application of electric fields or mechanical stress. We show that piezoelectric materials are capable of producing nonlocal forces of induction in external objects and we conclude that the nature of the forces generated is not originated from traditional interactions. Further we specifically assert that the generation of forces by the piezoelectric materials is ruled by the hypothesis of preexisting condition of generalized quantum entanglement between the molecular structure of the material bulk and the surrounding environment. In addition, the widely spread coupling of the molecules with the environment can be manifested from the so-called direct effect or the converse effect in piezoelectric materials and this coupling is not intermediated by acoustic waves or electromagnetic fields. We show that the novel effect has a theoretical explanation consistent with the generalized quantum entanglement framework and the direction of the induced forces depends on either the direction of the mechanical force or the electric field applied in these materials.

Preparation and characterization of Li_2Mo_(0.9)La_(0.2)O_4 anode material

La-doped Li2Mo0.9La0.2O4 was synthesized as an active anode material via the sol-gel process. The structural and morphological characteristics of the target product and the precursor were analyzed by XRD, SEM, and TG-DTA. Crystal started to format at 300℃ and the optimum crystal structure was obtained at 700℃. By detecting battery performance, the charged and discharged platform was over 3.6 V; the anode exhibited a discharge capacity decay of 2% from its initial capacity （165 mA·h/g） after 20 cycles. Therefore, it was a perfect anode material.

Impact of train speed on the mechanical behaviours of track-bed materials

For the 30,000 km long French conventional railway lines(94% of the whole network),the train speed is currently limited to 220 km/h,whilst the speed is 320 km/h for the 1800 km long high-speed lines.Nowadays,there is a growing need to improve the services by increasing the speed limit for the conventional lines.This paper aims at studying the influence of train speed on the mechanical behaviours of track-bed materials based on field monitoring data.Emphasis is put on the behaviours of interlayer and subgrade soils.The selected experimental site is located in Vierzon,France.Several sensors including accelerometers and soil pressure gauges were installed at different depths.The vertical strains of different layers can be obtained by integrating the records of accelerometers installed at different trackbed depths.The experimentation was carried out using an intercity test train running at different speeds from 60 km/h to 200 km/h.This test train was composed of a locomotive(22.5 Mg/axle) and 7 'Corail'coaches(10.5 Mg/axle).It was observed that when the train speed was raised,the loadings transmitted to the track-bed increased.Moreover,the response of the track-bed materials was amplified by the speed rise at different depths:the vertical dynamic stress was increased by about 10% when the train speed was raised from 60 km/h to 200 km/h for the locomotive loading,and the vertical strains doubled their quasistatic values in the shallow layers.Moreover,the stressestrain paths were estimated using the vertical stress and strain for each train speed.These loading paths allowed the resilient modulus Mrto be determined.It was found that the resilient modulus(M_r) was decreased by about 10% when the train speed was increased from 100 km/h to 200 km/h.However,the damping ratio(D_r) kept stable in the range of speeds explored.

A Theory for Anisotropic Magnetoresistance in Materials with Two Vector Order Parameters

Anisotropic magnetoresistance(AMR)and related planar Hall resistance(PHR)are ubiquitous phenomena of magnetic materials.Although the universal angular dependences of AMR and PHR in magnetic polycrystalline materials with one order parameter are well known,no similar universal relation for other class of magnetic materials are known to date.Here a general theory of galvanomagnetic effects in magnetic materials is presented with two vector order parameters,such as magnetic single crystals with a dominated crystalline axis or polycrystalline non-collinear ferrimagnetic materials.It is shown that AMR and PHR have a universal angular dependence.In general,both longitudinal and transverse resistivity are non-reciprocal in the absence of inversion symmetry:Resistivity takes different values when the current is reversed.Different from simple magnetic polycrystalline materials where AMR and PHR have the same magnitude,and π/4 out of phase,the magnitudes of AMR and PHR of materials with two vector order parameters are not the same in general,and the phase difference is not π/4.Instead ofπperiodicity of the usual AMR and PHR,the periodicities of materials with two order parameters are 2π.

An Improved Preisach Distribution Function Identification Method Considering the Reversible Magnetization

This paper presents an identification method of the scalar Preisach model to consider the effect of reversible magnetization in the process of distribution function identification.By reconsidering the identification process by stripping the influence of reversible components from the measurement data,the Preisach distribution function is identified by the pure irreversible components.In this way,the simulation accuracy of both limiting hysteresis loops and the inner internal symmetrical small hysteresis loop is ensured.Furthermore,through a discrete Preisach plane with a hybrid discretization method,the irreversible magnetic flux density components are computed more efficiently through the improved Preisach model.Finally,the proposed method results are compared with the traditional method and the traditional method considering reversible magnetization and validated by the laboratory test for the B30P105 electrical steel by Epstein frame.

不确定数据上的Reverse Top-k查询

传统的top-k查询为顾客返回符合其偏好的产品集合,reverse top-k查询则返回将给定产品作为top-k结果的偏好集合。reverse top-k查询由于能帮助生产者评估产品对顾客的影响,因此在商业分析中具有重要价值。现有的reverse top-k查询假设数据是精确的,许多现实应用中,数据的不确定性广泛存在。将reverse top-k查询扩展到不确定数据上,并给出了基于物化视图的高效查询算法GMV。实验结果表明,GMV算法能够减少需要计算的偏好数量,具有较高的计算效率。

Local structural characteristics of Sb_2Te_3 films studied by reverse Monte Carlo modeling

Atomic configuration and connectivity of Sb_2Te_3 thin film are investigated using high-energy X-ray diffraction and reverse Monte Carlo simulation. Atomic model details of Sb_2Te_3 thin film are compared with liquid and amorphous Sb_2Te_3 reported in other article. Simulations show that both Sb–Sb and Te–Te homopolar bonds are present in the models. In phase transition process,atomic configuration of the sample rearranges gradually through the forming of Sb–Te bonds and the breaking of Sb–Sb and Te–Te bonds.

A generalized Norde plot for reverse biased Schottky contacts

When a metal makes intimate contact with a semiconductor material, a Schottky barrier may be created. The Schottky contact has many important applications in the integrated circuit （IC） electronics field. The parameters of such contacts can be determined from their current-voltage （I-V） characteristics. The literature contains many proposals for extracting the contact parameters using graphical methods. However, such methods are generally applicable only to contacts with a forward bias, whereas many Schottky contacts actually operate un- der a reverse bias. Accordingly, the present study proposed a generalized reverse current-voltage （I-V） plot which enables the series resis- tance, barrier height, and ideality factor of a reverse biased Schottky contact to be extracted from a single set of I-V measurements. A theo- retical derivation of the proposed approach was presented and a series of validation tests were then performed. The results show that the pro- posed method is capable of extracting reliable estimates of the contact parameters even in the presence of experimental noise.

Numerical analysis of reverse dual-rotation friction stir welding process

A three-dimensional model of reverse dual-rotation friction stir welding （RDR-FSW） is developed to conduct the numerical simulation of heat generation and material flow during the process. The reverse rotation of the assisted shoulder and the tool pin is considered to model the heat generation rate. The predicted temperature difference between the advancing side and the retreating side in RDR-FSW is less than that in conventional FSW. There are two reverse flows during the RDR-FSW which is beneficial to the uniformity of the temperature profile. Due to the reverse rotation effects of the assisted shoulder, the predicted shape and size of thermal-mechanically affected zone （TMAZ） based on the iso-viscosity line are decreased greatly compared to the conventional FSW. It lays solid foundation for optimizing the process parameters in RDR-FSW.

船舶建造物资逆向物流流程优化

随着人们环保意识的增强和政府环境立法速度加快,逆向物流被社会各界越来越多人士所重视,而目前船舶建造物资逆向物流存在安全隐患、时间和储存成本较高、物资再利用度有待提高等问题,为实现船舶建造业降本增效,需对其逆向物流流程进行剖析和优化。将降低流程时间、减少流程中问题环节作为优化目标,应用Petri网络与六西格玛管理法建立DMAIC-Petri模型,随后基于ESIA等原则进行优化并提出改进建议。以高技术远洋客船建造危险废弃物为例,结果显示,优化后流程问题环节个数减少且流程完成时间降低了18.6%。研究表明该优化方法达到了优化目标,并为船舶建造物资逆向物流管理提供实际参考。

BPA可逆热敏变色复合材料制备方法及其应用研究进展

综述了BPA可逆热敏变色材料的制备及其应用,以及复配法、无机包覆法、微胶囊法、湿成膜法和近年来的2,6-单取代双酚A复合膜新方法,并分析了2,6-单取代法中膜结晶相变与二醛、酚醛树脂及胶种的关系。2,6-单取代双酚A线型或芳香酚醛树脂及其复合膜有机体系的设计与研究将进一步推动该类材料在具有可调的迟滞响应相变智能窗口,超低温变色敏感性、变色深度、稳定性,环境友好型合成树脂及塑料及实验教学等方面的应用。

可逆感温变色非织造材料的制备及性能研究

以非织造材料和感温变色油墨为原料,通过丝网印刷技术制备可逆感温变色非织造材料。测试并分析了丝网印刷前后试样微观形貌和化学结构的变化,讨论了丝网印刷次数对可逆感温变色非织造材料厚度、力学性能、变色性能和皂洗色牢度的影响。采用红蓝复合油墨对非织造材料进行整理,研究人体温度作用下可逆感温变色非织造材料的直观变色效果。结果表明:随着印刷次数的增加,整理后的非织造材料厚度、断裂强力和断裂伸长增加,初始色相加深,完全变色时间延长,皂洗色牢度GS评级提高。人体手指触摸试验结果表明,制备的非织造材料可在3 s内快速变色,具有灵敏的可逆感温变色性能。

基于壳聚糖/银离子的可逆温敏水凝胶的制备与性能

以壳聚糖(CS)和AgNO_(3)为主要原料,通过CS与Ag^(+)的超分子络合作用制备了一系列可逆温敏CS-Ag水凝胶,采用FTIR、XRD、XPS、SEM和EDS对CS-Ag水凝胶的结构和化学状态进行了表征。结果表明,通过同时调节AgNO_(3)用量和体系pH可制备具有相同凝胶温度的CS-Ag水凝胶。当CS用量为0.60 g、AgNO_(3)用量为0.19 g、体系总体积为21 mL、保持水凝胶pH=4.24时,制备的CS-Ag-19水凝胶凝胶温度为50℃,具有最佳的热可逆性能,至少可循环相变5次,具有室温避光保存5个月的稳定性,并表现出对大肠杆菌良好的抗菌性能。CS-Ag-19的溶胶-凝胶转换是由CS的氨基在不同温度下的超分子相互作用控制,H^(+)和Ag^(+)在温度、浓度变化的驱动下,对游离氨基的竞争反应(质子化和络合作用)之间的平衡关系使水凝胶具有温敏可逆性。CS-Ag-19水凝胶的可注射和温敏凝胶性能使其具有作为水凝胶抗菌敷料的应用潜力。

光响应聚合物的结构动态调控

近年来,动态光响应聚合物因其在光照条件下实现结构调控的先进性而备受关注。通过可逆的光化学反应,这类材料在特定波长和强度的光照下能够实现分子水平的精确控制,表现出卓越的性能和广泛的应用前景。本文深入探讨了结构可调的光响应主链聚合物、可逆光响应交联材料以及光响应超分子聚合物等关键领域。在综述中,详细总结了动态光响应聚合物在材料科学中的最新进展,为该领域的科学创新和应用拓展提供了系统性的参考和有价值的展望。

Dopant-free hole transporting materials with supramolecular interactions and reverse diffusion for efficient and modular p-i-n perovskite solar cells

The rational design of dopant-free organic hole-transporting layer(HTL) materials is still a challenge for realizing high-efficient and stable p-i-n planar perovskite solar cells(pero-SCs). Here, we synthesized two π-conjugated small-molecule HTL materials through tailoring the backbone and conjugated side chain to carefully control molecular conformation. The resultant BDT-TPAs Th containing a planar fused benzo[1,2-b:4,5-b′]dithiophene(BDT) core and a conjugated thiophene side chain showed the planar conformation. X-ray crystallography showed a favorable stacking model in solid states under the parallel-displaced π-πand additional S-π weak-bond supramolecular interactions, thus achieving an obviously increased hole mobility without dopants.As an HTL material in p-i-n planar pero-SCs, the marginal solubility of BDT-TPA-s Th enabled inverse diffusion into the perovskite precursor solution for assisting the subsequent perovskite film growth and passivating the uncoordinated Pb2+ ion defects. As a result, the planar p-i-n pero-SCs exhibited a champion power conversion efficiency(PCE) of 20.5% and enhanced moisture stability. Importantly, the BDT-TPA-s Th HTL material also showed weak thickness-photovoltaic dependence, and the pero-SCs with blade-coated BDT-TPA-s Th as a HTL achieved a 15.30% PCE for the 1-cm2 modularized device. This HTL material design strategy is expected to pave the way toward high-performance, dopant-free and printing large-area planar p-i-n pero-SCs.

复合材料圆筒损伤的改进时间反转导波监测

针对复合材料阻尼较大导致传统概率成像方法存在损伤定位精度较低的问题,提出了基于改进时间反转导波的概率成像方法,并用于复合材料圆筒的损伤监测中。该方法通过在时域内反转压电传感器接收到的响应导波信号,将其记录为参考再发射信号(RRS)。分别在健康和损伤状态下激发相同的RRS信号,重建两种工况下的原始激励信号。将重构信号在健康状态下与损伤状态下的能量比值作为损伤指标,结合现有的概率成像方法实现对损伤的定位和成像。对复合材料圆筒上的模拟损伤开展了试验验证,并与传统方法的损伤定位精度进行了比较。结果表明,改进时间反转法对复合材料结构的损伤具有更高的定位精度及更好的敏感性,验证了该方法在复合材料结构脱粘损伤定位中的可行性和准确性。

Preparation of biomass-derived carbon loaded with MnO_(2) as lithium-ion battery anode for improving its reversible capacity and cycling performance

Biomass-derived carbon materials for lithiumion batteries emerge as one of the most promising anodes from sustainable perspective.However,improving the reversible capacity and cycling performance remains a long-standing challenge.By combining the benefits of K2CO_(3) activation and KMnO_(4) hydrothermal treatment,this work proposes a two-step activation method to load MnO_(2) charge transfer onto biomass-derived carbon(KAC@MnO_(2)).Comprehensive analysis reveals that KAC@MnO_(2) has a micro-mesoporous coexistence structure and uniform surface distribution of MnO_(2),thus providing an improved electrochemical performance.Specifically,KAC@MnO_(2) exhibits an initial chargedischarge capacity of 847.3/1813.2 mAh·g^(-1) at 0.2 A·g^(-1),which is significantly higher than that of direct pyrolysis carbon and K2CO_(3) activated carbon,respectively.Furthermore,the KAC@MnO_(2) maintains a reversible capacity of 652.6 mAh·g^(-1) after 100 cycles.Even at a high current density of 1.0 A·g^(-1),KAC@MnO_(2) still exhibits excellent long-term cycling stability and maintains a stable reversible capacity of 306.7 mAh·g^(-1) after 500 cycles.Compared with reported biochar anode materials,the KAC@MnO_(2) prepared in this work shows superior reversible capacity and cycling performance.Additionally,the Li+insertion and de-insertion mechanisms are verified by ex situ X-ray diffraction analysis during the chargedischarge process,helping us better understand the energy storage mechanism of KAC@MnO_(2).

基于气相色谱-质谱联用的喷气燃料详细烃类组成快速分析技术的应用

针对当前喷气燃料烃类组成测定存在自动化程度低、分析时间长、步骤繁琐和精密度差等问题,设计并提出了一套基于气相色谱(GC)预分离与质谱(MS)分析相结合的喷气燃料详细烃类组成快速分析技术,并形成了由分析方法、分析系统及分析平台组成的全流程解决方案。某炼油厂现场应用结果显示:喷气燃料详细烃类组成快速分析技术测定结果与现有标准方法测定结果具有良好的一致性,实施的技术方案在不同厂家的GC-MS仪器上的测定结果具有良好的一致性。喷气燃料详细烃类组成快速分析技术可在9 min内完成喷气燃料中13种详细烃类(包含烯烃)含量的测定,且分析过程全自动化、绿色化,技术经济性优势显著。

Measurement of the echo reduction for underwater acoustic passive materials by using the time reversal technique

A measuring method of the echo reduction of passive materials by using the time reversal（TR） technique is presented. To measure the echo reduction of a sample with this approach, the received signals are firstly focused according to the TR theory. Then, the sample is removed and the TR processing is again employed to realize the focus of the received signal.Finally, the echo reduction of the sample is evaluated with these focusing signals. Besides, to calibrate the measured echo reduction via the TR technique, a standard sample is employed to measure a constant coefficient that only depends on the measurement environment. An aluminum plate sample and a steel plate sample with the same size of 1.1 mxl.O m x0.005 m axe tested in a wave guide tank. The experimental results show that the calibrated values are well consistent with theoretical results under the free field at the measured frequency range of0.5-20 kHz. The relative errors of all the measured values are less than 10% and the values of the expanded uncertainty are less than 1.5 dB. The TR processing focuses the energy in spatial domain and temporal domain, so it can be used to measure the echo reduction of passive materials in the environments with reflections induced by boundaries and low frequency sources.