TMDs阻变存储器微观机理研究综述

过渡金属硫族化合物(TMDs)阻变存储器具有简单的金属-介质层-金属三明治结构,且功耗低、可缩性好。分析TMDs阻变存储器阻变机理和导电细丝形成特性,为明确阻变存储器机理模拟研究重点提供理论基础。总结分析了国内外存储层TMDs的范德华层间空隙半径、掺杂和缺陷状况与器件性能之间的关系,展望了TMDs阻变存储器的发展趋势和应用前景,为TMDs阻变存储器技术攻关提供支撑。

多种分辨率HDMI接口的TMDS信号转为LVDS格式实现方法研究

为了将图像仿真系统输出的高清多媒体接口(High Definition Multimedia Interface,HDMI)最小化传输差分信号(Transition Minimized Differential Signaling,TMDS)转换为摄像头模组接口低电压差分信号(Low-Voltage Differential Signaling,LVDS),文章联合使用ITE68051芯片和现场可编程逻辑门阵列芯片(Field Programmable Gate Array,FPGA)实现了相应的转换。首先,将高清、超高清HDMI接口的TMDS信号通过ITE68051视频处理芯片进行TMDS解码,以双端口方式输出并行RGB数字信号;然后,应用FPGA易编程性的特点,将多种分辨率的RGB信号转换为相应的LVDS信号。联合应用ITE68051和FPGA芯片架构的转换系统,便于视频设备之间的兼容和系统后续升级,为自动驾驶仿真系统的视频信号输入提供了可靠的硬件接口通道。

Current advances of transition metal dichalcogenides in electromagnetic wave absorption:A brief review

Transition metal dichalcogenides(TMDs)show great advantages in electromagnetic wave(EMW)absorption due to their unique structure and electrical properties.Tremendous research works on TMD-based EMW absorbers have been conducted in the last three years,and the comprehensive and systematical summary is still a rarity.Therefore,it is of great significance to elaborate on the interaction among the morphologies,structures,phases,components,and EMW absorption performances of TMD-based absorbers.This review is devoted to analyzing TMD-based absorbers from the following perspectives:the EMW absorption regulation strategies of TMDs and the latest progress of TMD-based hybrids as EMW absorbers.The absorption mechanisms and component-performance dependency of these achievements are also summarized.Finally,a straightforward insight into industrial revolution upgrading in this promising field is proposed.

Defect-engineered two-dimensional transition metal dichalcogenides towards electrocatalytic hydrogen evolution reaction

Recently,two-dimensional transition metal dichalcogenides(TMDs)demonstrated their great potential as cost-effective catalysts in hydrogen evolution reaction.Herein,we systematically summarize the existing defect engineering strategies,including intrinsic defects(atomic vacancy and active edges)and extrinsic defects(metal doping,nonmetal doping,and hybrid doping),which have been utilized to obtain advanced TMD-based electrocatalysts.Based on theoretical simulations and experimental results,the electronic structure,intermediate adsorption/desorption energies and possible catalytic mechanisms are thoroughly discussed.Particular emphasis is given to the intrinsic relationship between various types of defects and electrocatalytic properties.Furthermore,current opportunities and challenges for mechanical investigations and applications of defective TMD-based catalysts are presented.The aim herein is to reveal the respective properties of various defective TMD catalysts and provide valuable insights for fabricating high-efficiency TMD-based electrocatalysts.

二维TMDs析氢催化剂的改性和耦合产电研究进展

二维过渡金属硫属化合物(2D TMDs)具有比表面积大和电子结构可调的优点,被认为是电催化析氢反应(HER)最具前景的非贵金属催化材料。而纯的2D TMDs的活性位点数量有限且电导率不够高,通过对其进行有效改性,可优化氢吸附自由能、提高导电率、增加催化剂活性位点数量以提升本征催化性能。本文综述了对近年来2D TMDs基电催化剂在HER中的应用研究进展,以促进电解水制氢的进一步发展。重点分析了改性策略及相应的制备方法、电解水析氢性能与影响机制以及耦合产电应用进展,最后对2D TMDs在HER及耦合产电应用中面临的挑战进行分析与展望。

Thermal transport properties of two-dimensional boron dichalcogenides from a first-principles and machine learning approach

The investigation of thermal transport is crucial to the thermal management of modern electronic devices.To obtain the thermal conductivity through solution of the Boltzmann transport equation,calculation of the anharmonic interatomic force constants has a high computational cost based on the current method of single-point density functional theory force calculation.The recent suggested machine learning interatomic potentials(MLIPs)method can avoid these huge computational demands.In this work,we study the thermal conductivity of two-dimensional MoS_(2)-like hexagonal boron dichalcogenides(H-B_(2)VI_(2);V I=S,Se,Te)with a combination of MLIPs and the phonon Boltzmann transport equation.The room-temperature thermal conductivity of H-B_(2)S_(2)can reach up to 336 W·m^(-1)·K^(-1),obviously larger than that of H-B_(2)Se_(2)and H-B_(2)Te_(2).This is mainly due to the difference in phonon group velocity.By substituting the different chalcogen elements in the second sublayer,H-B_(2)VIV I′have lower thermal conductivity than H-B_(2)VI_(2).The room-temperature thermal conductivity of B2STe is only 11%of that of H-B_(2)S_(2).This can be explained by comparing phonon group velocity and phonon relaxation time.The MLIP method is proved to be an efficient method for studying the thermal conductivity of materials,and H-B_(2)S_(2)-based nanodevices have excellent thermal conduction.

MoiréDirac fermions in transition metal dichalcogenides heterobilayers

Monolayer group-VIB transition metal dichalcogenides(TMDs)feature low-energy massive Dirac fermions,which have valley contrasting Berry curvature.This nontrivial local band topology gives rise to valley Hall transport and optical selection rules for interband transitions that open up new possibilities for valleytronics.However,the large bandgap in TMDs results in relatively small Berry curvature,leading to weak valley contrasting physics in practical experiments.Here,we show that Dirac fermions with tunable large Berry curvature can be engineered in moirésuperlattice of TMD heterobilayers.These moiréDirac fermions are created in a magnified honeycomb lattice with its sublattice degree of freedom formed by two local moirépotential minima.We show that applying an on-site potential can tune the moiréflat bands into helical ones.In short-period moirésuperlattice,we find that the two moirévalleys become asymmetric,which results in a net spin Hall current.More interestingly,a circularly polarized light drives these moiréDirac fermions into quantum anomalous Hall phase with chiral edge states.Our results open a new possibility to design the moiré-scale spin and valley physics using TMD moiréstructures.

Growing Biomorphic Transition Metal Dichalcogenides and Their Alloys Toward High Permeable Membranes and Efficient Electrocatalysts Applications

3D architecratured transition metal dichalcogenides constructed by atomically thin layers are appealing building blocks in various applications,such as catalysts,energy storage,conversions,sensors,and so on.However,the direct growth of 3D transition metal dichalcogenides architectures with high crystal quality and well-controlled size/thickness remains a huge challenge.Herein,we report a facile,highly-repeatable,and versatile chemical vapor deposition strategy,for the mass production of high-quality 3D-architecratured transition metal dichalcogenides(e.g.,MoS_(2),WS_(2),and ReS_(2))and their alloys(e.g.,W_(x)Mo(1–x)S_(2)and Rex Mo_((1–x))S_(2))nanosheets on naturally abundant and low-cost diatomite templates.Particularly,the purified transition metal dichalcogenides products exhibit unique and designable 3D biomorphic hierarchical microstructures,controllable layer thicknesses,tailorable chemical compositions,and good crystallinities.The weak interlayer interactions endow them with good dispersity in solutions to form stable additive-free inks for solution-processing-based applications,for example,high-permeable and high-stable separation membranes for water purification,and efficient electrocatalysts for hydrogen evolution reactions.This work paves ways for the low-cost,mass production of versatile transition metal dichalcogenides powder-like materials with designable structures and properties,toward energy/environmental-related applications and beyond.

Hydrogenic donor impurity states and intersubband optical absorption spectra of monolayer transition metal dichalcogenides in dielectric environments

The hydrogenic donor impurity states and intersubband optical absorption spectra in monolayer transition metal dichalcogenides(ML TMDs) under dielectric environments are theoretically investigated based on a two-dimensional(2D)nonorthogonal associated Laguerre basis set. The 2D quantum confinement effect together with the strongly reduced dielectric screening results in the strong attractive Coulomb potential between electron and donor ion, with exceptionally large impurity binding energy and huge intersubband oscillator strength. These lead to the strong interaction of the electron with light in a 2D regime. The intersubband optical absorption spectra exhibit strong absorption lines of the non-hydrogenic Rydberg series in the mid-infrared range of light. The strength of the Coulomb potential can be controlled by changing the dielectric environment. The electron affinity difference leads to charge transfer between ML TMD and the dielectric environment, generating the polarization-electric field in ML TMD accompanied by weakening the Coulomb interaction strength. The larger the dielectric constant of the dielectric environment, the more the charge transfer is, accompanied by the larger polarization-electric field and the stronger dielectric screening. The dielectric environment is shown to provide an efficient tool to tune the wavelength and output of the mid-infrared intersubband devices based on ML TMDs.

西安城市展示中心长悬挑、大跨度钢结构设计

西安城市展示中心由南馆、北馆和连桥组成,其中南馆悬挑长度62m,连桥跨度150m。结合建筑方案特点,南馆与连桥采用整层钢桁架结构体系,结构布置与建筑形态高度契合。介绍了南馆、连桥、穹顶、屋面等位置的结构布置情况,明确了超限项和抗震性能目标,对于多杆件复杂交汇钢节点进行有限元分析。针对南馆、连桥屋楼盖振动舒适度不足,设计布置了调谐质量阻尼器(TMD),实测减振效果显著。对连桥提升过程进行施工模拟,结果表明该过程增加了连桥挠度,需要考虑提前起拱。对超长连体结构温度和地震行波效应进行分析,根据结果对连桥楼板配筋和局部框架柱进行了加强。大震弹塑性分析与防连续倒塌分析结果表明,结构满足“大震不倒”的性能目标,结构冗余度较高,具有良好的防连续倒塌能力。

基于气动措施和滑轮式TMD的人行景观桥涡振混合控制研究

为了解决传统式调谐质量阻尼器(tuned mass damper, TMD)在控制低频桥梁结构中弹簧静伸长过长的问题,介绍了滑轮式TMD及其用于结构振动控制时的特点,指出滑轮式TMD可以有效减小弹簧静伸长量。以一座人行景观桥为例,研究了采用气动措施和滑轮式TMD对该桥的涡振控制效果。风洞试验结果显示,在最优气动措施下,主梁的涡振振幅减少了一半以上,但仍未达到行人舒适性要求。基于Scanlan线性涡激力模型进行滑轮式TMD的优化设计,在气动措施的基础上进一步辅以滑轮式TMD进行涡振控制。分析结果表明,气动措施结合滑轮式TMD进行涡振控制能够满足行人舒适性要求,并确保滑轮式TMD质量块的工作行程不超过限值。通过同时采用气动措施和滑轮式TMD,可以满足主梁涡振限值、TMD弹簧静伸长量和工作行程等多重要求,从而有效控制主梁的涡振现象。本文提出的混合控制方案为类似工程中的涡振控制提供了有益参考,可为工程实践提供指导。

桥梁抗风型TMD对车-桥耦合振动系统减振性能研究

为研究桥梁抗风型调谐质量阻尼器(tuned mass damper, TMD)对车辆荷载引起结构振动的减振效果,并揭示车载作用下的TMD激振机理,提出了基于模态动能演化的多自由度结构TMD控制方法,确定了安装TMD的最优设计参数和布设位置;考虑桥梁有限元模型动力求解的通用性,基于桥梁三维动力分析系统BDANS软件建立了车-桥-TMD动力耦合分析系统;以经典单自由度移动弹簧质量过简支梁模型为研究对象,分析了车-桥-TMD系统振动特性,结合某深水区非通航桥梁抗风型TMD工程实例分析了TMD对车致振动的减振效果和机理。研究结果表明:TMD行程幅值与减振效果呈现正相关特点,即行程幅值越大对车-桥动力效应引起的振动减振效果越好;安装TMD可以显著提高结构的等效阻尼比,满足等效阻尼比>1%的工程需求,提高桥梁结构振动的稳定性;TMD在一定条件下可以减小车辆通过时引发桥梁竖向位移冲击效应,最大可减少3%左右;TMD对车-桥2个子系统的加速度瞬态峰值均起到了一定的抑制效果,尤其对桥梁结构竖向振动加速度作用效果明显,安装TMD后的桥梁跨中竖向振动加速度RMS值减少约20%;对大跨钢箱桥梁而言,相比较小的车辆荷载冲击效应,一阶竖弯呈邻跨反对称特性的桥梁结构在车辆通行过程中更容易激起TMD,使桥梁结构获得更佳的减振效果。

高层钢结构TMDs风振舒适度控制最优参数与简化设计

分别将脉动风视为白噪声和采用Davenport风速谱 ,基于建筑荷载规范GBJ9-87,导出了高层钢结构_TMD系统减振系数DRF1和DRF2 。数值研究表明 :高层钢结构的基本周期和基本风压不影响TMDs最优设计参数 ;将脉动风设为白噪声或采用Davenport风速谱时 ,TMDs最优设计参数未有改变 ,但减振系数略有变化。同时 ,基于导出的高层钢结构TMD -系统加速度传递函数及加速度动力放大系数 ,研究了TMDs最优参数取值。提出了高层钢结构TMD风振舒适度控制简化设计过程。数值算例说明了本文方法的应用及TMDs对高层钢结构风振舒适度控制的有效性。

DVI接口的TMDS链路通讯中抖动问题研究

DVI接口的数据传输信号频率已接近微波波段,在如此高速串行数据通讯中会表现出典型的抖动效应。DVI接口电路设计中抖动是DVI接口的TMDS链路通讯的最为关心的问题之一,本文从TMDS连路结构及时钟同步与数据恢复两个方面对链路的抖动问题进行研究,并给出一些解决方案。

DVI接口的TMDS差分信号研究

本文对TMDS链路接口系统正常工作参数和接收器的直流、交流特性参数、测试电路以及所引起的眼图变化进行了分析,并给出了数据传输中数据是否能正确恢复的原因。

100 m X-BOW型极地探险邮轮局部振动控制

为提高乘客舒适度,利用调谐质量阻尼器(tuned mass damper,TMD)对100 m X-BOW型极地探险邮轮的局部振动进行控制。建立邮轮的有限元模型,进行整船频响分析,通过比较仿真值与测试值间的误差,验证模型的有效性。根据整体模态等价质量求解方法和局部模态质量的空间分布原则,提出混合模态中单个局部模态等价质量的求解方法,利用该方法求解邮轮局部振动区域的等价质量;利用该等价质量计算TMD的质量比;基于该质量比,求解出对应的TMD参数最优解。通过分析可知,当质量比为0.05时,TMD在13.4 Hz处具有31 dB的吸振效果,同时在10 Hz和18.8 Hz处也有一定的吸振效果,分别为3 dB和2 dB,整体控制频段较平坦,鲁棒性也较佳。

某新建工业厂房有限元分析及减振设计

在生产设备自身振动及噪声等多因素耦合下,厂房结构产生不良振动反应,轻则减少设备使用寿命,影响企业正常生产,重则造成厂房坍塌,造成极大的生命和财产损失。通过对已建工业厂房的振动形式和异常振动原因进行分析,拟在原已建工业厂房附近建设一座功能相同、产量高、性能齐全的大型工业厂房。为减小新建厂房设备生产时对屋面的扰动,降低交变荷载对屋面防水系统的扰动,提出采用调谐质量阻尼器(TMD)进行减振耗能,以保障厂房生产安全,提高使用寿命。通过研究,有效解决了大型动力工业厂房结构异常振动的难题,提高了我国工业厂房的设计水平,为工业厂房的应用提供了参考。

园艺疗法对大学生心理素质提升的应用研究

探究园艺疗法对大学生心境状态的缓解与心理素质提升的效益,以期为园艺疗法在高校中的推广应用提供参考。通过开展10种园艺活动,运用POMS量表与满意度调查进行量化、质性分析。结果显示,10种园艺活动参与者的心境状态TMD均有所下降,平均降低12.68;植物识别、叶脉书签、植物播种、植物拓印、多肉栽植与香囊制作等活动均能够显著改善大学生的消极情绪;各园艺活动对具体心境状态疲劳(2.50)、抑郁(2.05)与紧张(1.91)情绪改善效果较好,其中植物拓印活动最好,可显著改善6个心境状态;各园艺活动总体满意度评价均值为8.10,总体评价较好,其中香囊制作与多肉栽植的满意度较高。研究表明各园艺活动均对参与者的情绪有一定改善作用,植物识别、植物播种、多肉栽培与香囊制作对参与者的心理状况改善较好;园艺疗法可一定程度地提升大学生心理素质,将园艺疗法运用到大学生心理健康教育具有一定的可行性。

ZnCo_(2)O_(4)-ZnO@C@CoS核壳复合材料的制备及其在超级电容器中的应用

超级电容器以其高功率性能、稳定的循环性能和优良的安全性等独特优势,作为储能器件在新能源汽车和移动电子设备等方面极具前景。然而,其能量密度相对较低,限制了实际应用。为提升电化学活性,本研究通过简便的溶剂热法、煅烧处理和电化学沉积技术,在碳包覆的ZnCo_(2)O_(4)-ZnO微球上沉积了CoS纳米片(ZCO-ZO@C@CoS)。碳层不仅可以促进电子传输,增强导电性,还提升了结构的稳定性;CoS纳米片之间形成的开放网络空间促进了离子快速传输。此外,CoS纳米片具备丰富的电活性位点,实现了快速可逆的氧化还原反应;核壳结构内部的纳米线、碳层和外层纳米片的共同作用,有效提升了材料的整体电化学性能。因此,ZCO-ZO@C@CoS在1.5 A·g^(−1)时的比电容达到1944 F·g^(−1)(972.0 C·g^(−1)),20 A·g^(−1)高电流密度下循环10000次后比容量保持率为75%。由ZCO-ZO@C@CoS(正极)和活性炭(负极)组成的非对称超级电容器器件也表现出优异的比电容、高的倍率性能和优异的循环稳定性,显示出良好的应用前景。

利用TMDS均衡技术实现HDMI信号的远距离传输

针对数字高清多媒体接口(HDMI)信号的传输特性,利用TMDS均衡技术,本文提出了实现HDMI信号的远距离传输的具体方案,解决了HDMI信号电缆传输距离不能满足高清电视、DVD、显卡、数字投影议等设备需要的问题。