Electronic structures of stacked layers quantum dots:influence of the non-perfect alignment and the applied electric field

Electronic structures of the artificial molecule comprising two truncated pyramidal quantum dots vertically coupled and embedded in the matrix are theoretically analysed via the finite element method. When the quantum dots are completely aligned, the electron energy levels decrease with the horizontally applied electric field. However, energy levels may have the maxima at non-zero electric field if the dots are staggered by a distance of several nanometers in the same direction of the electric field. In addition to shifting the energy levels, the electric field can also manipulate the electron wavefunctions confined in the quantum dots, in company with the non-perfect alignment.

The Electrical and Mechanical Alignment and Accuracy Detection of Numerial Control Machine Tool

In the work of numerical control reformation of general machine tool, the installation and debugging of machine tool is a crucial part. For the C6132 machine tool, and make the use of electrical and mechanical alignment, parameter adjusting, numerical control lathe accuracy debugging and performance examination has been used to finish a series of tailing in the work of numerical control reformation of general machine tool. In this paper, the detailed process of electrical and mechanical alignment, parameter adjusting, numerical control lathe accuracy debugging and performance examination has been demonstrated, meanwhile, the specific operational approach of these work programs has been discussed. Therefore, the present results provides essential reference and approach for the numerical control reformation of general machine tool.

Electrical and Piezoresistive Properties of Steel Fiber Cement-based Composites Aligned by a Magnetic Field

Directionally distributed steel fiber cement-based composites(SFCCs)were prepared by magnetic field(MF)induction technology.The orientation factor of steel fibers in the as-obtained SFCCs was determined.Besides,the electrical resistivity and piezoresistive responses in two directions of aligned steel fiber cement-based composites,i e,parallel and perpendicular to MF,were measured.The effects of several variables,eg,steel fiber content,curing age,humidity,and temperature,on anisotropic electrical property were studied.The cyclic and failure piezoresistive responses in different directions were tested.It is found that the aligned steel fibers in the as-obtained SFCCs have a high orientation factor more than 0.88.Besides,SFCCs with aligned steel fibers exhibit an obvious anisotropic conductivity and piezoelectric sensitivity.The electrical conductivity of SFCCs with aligned steel fibers is less affected by temperature and humidity.At the steel fiber content of 2.5wt%,the piezoelectric sensitivity coefficient of SFCCs in the direction parallel to MF has the highest value of 324.14.In addition,the piezoresistive properties of SFCCs with aligned steel fibers in the direction parallel to MF indicate excellent sensitivity and stability under cyclic loading and monotonic loading.

Characteristics of LDPE and Oriented Montmorillonite Nanocomposites Produced by Electric Field-inducement

In order to make montmorillonite (MMT) nanosheets disperse in low-density polyethylene (LDPE) with highly homogeneous orientation, alternating voltage is applied to molten LDPE with MMT nanosheets. The effect of electric field on the dispersion of MMT in the solidified LDPE is studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses suggest that the MMT nano- sheets are aligned with high anisotropy to the electric field direction, which is perpendicular to the LDPE film plane. Differential scanning calorimetry (DSC) results reveal that the crystallization degree of the oriented LDPE/MMT composite increases. Moreover, through a broadband dielectric spectroscopy analyzer, it is found that MMT manifests a significantly influence in the dielectric property of the oriented composite: the dielectric constant and loss tangent of the composite both become larger. Analysis shows that the electric field-induced torque caused by the polarization of MMT flakes is the main force inducing the orientation of the MMT flakes.

Control of Microdomain Orientation in Block Copolymer Thin Films by Electric Field for Proton Exchange Membrane

Owing to the recent push toward efficient energy storage/conversion devices, fuel cells have become a strong candidate for energy conversion equipments. On the other hand, block copolymer polyelectrolytes are interesting materials for proton exchange membranes in fuel cells. Thus a considerable attention has been paid to the development of block copolymer polyelectrolyte membranes. In this study, the microdomains in block copolymer polyelectrolytes were controlled by external electric fields to develop high performance membranes with improved proton conductivity. The microdomain alignments in sulfonated polystyrene-b-hydrogenated poly butadiene-b-polystyrene block copolymer electrolyte were monitored by cross-sectional transmission electron microscopy analysis. The proton conductivities of the block copolymer electrolyte membranes were measured before and after exposure to electric field. In addition, the morphological features of the block copolymer electrolyte were observed with small angle x-ray scattering and atomic force microscopy.

XXJ20Y电动斜直井修井机的研制与应用

为满足斜直水平井修井作业需求和验证斜直井作业工艺参数,研制了XXJ20Y电动斜直井修井机。介绍了修井机的主要结构和原理,提出将油管作业空间由后端移至机身内的思路。创新对中方法和油管运移及摆放路线,设计相应的整机对中结构、井架结构和抓管、移管、排管结构。应用Pro/E和ANSYS Workbench 15.0等主流分析软件对井架和底座等关键零部件进行了三维建模和强度校核。该修井机进行了小规模的试验应用,达到了较高的自动化水平,操作手1人就可完成管柱起下作业,配合人员大幅减少,安全性提高;利用井场电源驱动,尾气零排放、噪声低,绿色环保;优化了油管运移结构及流程。该修井机的研制可为斜井修井机、电动修井机的研制和常规修井机的自动化改造提供借鉴。

Carbon nanotube fibers with excellent mechanical and electrical properties by structural realigning and densification

Floating catalysis chemical vapor deposition(FCCVD)direct spinning process is an attractive method for fabrication of carbon nanotube fibers(CNTFs).However,the intrinsic structural defects,such as entanglement of the constituent carbon nanotubes(CNTs)and inter-tube gaps within the FCCVD CNTFs,hinder the enhancement of mechanical/electrical properties and the realization of practical applications of CNTFs.Therefore,achieving a comprehensive reassembly of CNTFs with both high alignment and dense packing is particularly crucial.Herein,an efficient reinforcing strategy for FCCVD CNTFs was developed,involving chlorosulfonic acid-assisted wet stretching for CNT realigning and mechanical rolling for densification.To reveal the intrinsic relationship between the microstructure and the mechanical/electrical properties of CNTFs,the microstructure evolution of the CNTFs was characterized by cross-sectional scanning electron microscopy(SEM),wide angle X-ray scattering(WAXS),polarized Raman spectroscopy and Brunauer–Emmett–Teller(BET)analysis.The results demonstrate that this strategy can improve the CNT alignment and eliminate the inter-tube voids in the CNTFs,which will lead to the decrease of mean distance between CNTs and increase of inter-tube contact area,resulting in the enhanced inter-tube van der Waals interactions.These microstructural evolutions are beneficial to the load transfer and electron transport between CNTs,and are the main cause of the significant enhancement of mechanical and electrical properties of the CNTFs.Specifically,the tensile strength,elastic modulus and electrical conductivity of the high-performance CNTFs are 7.67 GPa,230 GPa and 4.36×10^(6)S/m,respectively.It paves the way for further applications of CNTFs in high-end functional composites.

浅谈极区空间物理学的科学革命

极区空间物理学重要的研究方向之一是剖析南北两极的热层、电离层和磁层的耦合问题。本文简明扼要地描述了极区空间物理学的一场革命——即理论框架的革新。这场科学革命是用磁流体力学理论取代电机工程理论,目前进行得比较缓慢,但将在今后的30~50年彻底改变人们对于热层-电离层-磁层的认知。

全喂入玉米联合收获机电气控制系统的设计

针对人工收割玉米劳动成本较高、收获效率低、茎秆焚烧造成环境污染且籽粒收获还需要对玉米进行二次加工等问题,对全喂入玉米联合收获机进行了设计,并重点对电气控制系统进行了研究。为了实现玉米联合收获机的智能化控制,对其自动对行和割台高度自动调控装置进行了设计。其中,自动对行装置采用Labview平台进行设计,割台高度采用PID控制器进行控制。为了验证该玉米联合收获机的性能,对其电气系统进行了玉米自动对行试验和割台高度自动调控试验。结果表明:玉米联合收获机可实现自动对行和割台高度自动调控。

带束层角度对电动汽车轮胎性能的影响

采用有限元技术研究带束层角度对205/55R16电动汽车轮胎接地印痕、侧偏刚度和回正刚度的影响。结果表明:随着带束层角度的增大,轮胎接地印痕由方形逐渐变成偏圆形,接地印痕短轴长度变小,接地印痕长轴长度增大,接地印痕面积增大;在相同负荷、不同充气压力和相同充气压力、不同负荷下,随着带束层角度的增大,轮胎侧偏刚度均减小,回正刚度均增大。

无人驾驶电机车自动卸矿技术研究与应用

5G、云计算、AI等ICT技术飞速发展,为传统矿山提供了全新的发展机遇。矿山面临资源不足、开采难度递增、单位矿石生产成本高、未来劳动力风险大等关键的结构性问题,迫切需要数字化、智能化手段加以解决。原矿石窄轨运输是矿山开采的重要工艺,无人驾驶电机车的部署对智能矿山建设意义重大,电机车无人驾驶作业过程中自动卸矿是无人驾驶的重要环节,也是无人驾驶需要突破的技术难点。本次研究应用激光传感器、激光雷达料位计、AI视觉、射频信标、高精编码等新技术的融合,完成电无人驾驶机车自动卸矿复杂工艺,能达到电机车无人驾驶目标及生产效率要求。

基于AHP-ELECTRE Ⅱ的公路“绿色”选线方案比选

公路建设对沿线自然环境有着重大影响,因此"绿色"选线过程中应充分考虑环境因素。利用层次分析法(AHP)建立层次分析模型并确定评价指标权重,然后利用消去与选择转换(ELECTRE Ⅱ)综合评价法,实现各路线方案的环境影响量化评价。通过实例,证明该方法可以较好应用于公路"绿色"选线方案比选。

Electric field-induced photoluminescence quenching in Pr-doped BNT ceramics across the MPB region

Piezophotonics is a great interesting field of physics that has led to a number of important technologies,such as light source,smart sensors,and mechatronics.In this work,we reported Pr-doped(Bi_(0.5)Na_(0.5))TiO_(3)-based lead-free ceramics with strong red photoluminescence emission and large strain response(d_(33)^(*)=460 pm/V,S=0.32%).The PL emission can be quenched by decreasing the intensity by 93%after electrical polarization(E=50 kV/cm).The local structure and electric field-induced structural changes were systematically investigated to reveal the significant distinction in photoluminescence properties caused by electrical polarization.The results indicated that polarization treatment eliminates the structural inhomogeneities and establishes a long-range ferroelectric tetragonal and rhombohedral distortion.The crystal structure transformed irreversibly from a non-ergodic to a normal ferroelectric state.PL quenching originated from the decreased distortion of octahedral due to the transition from a non-ergodic state to a highly ordered symmetrical structure.Meanwhile,the enlarged domain structure contributed to the photoluminescence quenching effect.Our findings demonstrate that an electric field can be a robust tool for adjusting the photoluminescence property and provide insights into the rela-tionship between the structure and PL properties of BNT-based ceramics under an external stimulus.

Coordinated shift control of nonsynchronizer transmission for electric vehicles based on dynamic tooth alignment

Multispeed transmissions can enhance the dynamics and economic performance of electric vehicles(EVs),but the coordinated control of the drive motor and gear shift mechanism during gear shifting is still a difficult challenge because gear shifting may cause discomfort to the occupants.To improve the swiftness of gear shifting,this paper proposes a coordinated shift control method based on the dynamic tooth alignment(DTA)algorithm for nonsynchronizer automated mechanical transmissions(NSAMTs)of EVs.After the speed difference between the sleeve(SL)and target dog gear is reduced to a certain value by speed synchronization,angle synchronization is adopted to synchronize the SL quickly to the target tooth slofs angular position predicted by the DTA.A two-speed planetary NS AMT is taken as an example to carry out comparative simulations and bench experiments.Results show that gear shifting duration and maximum jerk are reduced under the shift control with the proposed method,which proves the effectiveness of the proposed coordinated shift control method with DTA.

Phenomenon of multiple field-induced phase transition in PLZST antiferroelectric ceramics

The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phase to two ferroelectric phases are observed is polarization at the applied field of 4 MV/m. The critical field of phase transition between two ferroelectric phases is not larger than 2.5 MV/m, about ten to twenty percent of that ever found in PZT based ceramics. Lattice structure is shown to be orthorhombic by X-ray diffraction. Dielectric investigation reveals a relaxor-like ferroelectric behavior. Temperature-electric field phase diagram is also presented. An appreciate kind of materials is provided to investigate multiple field-induced phase transition with PZT-based ceramics.

人体静电电位信号数据对齐方法研究

针对多传感器检测系统相关试验中存在的多个传感器在数据采集过程中数据读取时间不同步以及采样频率不统一,导致数据对齐存在偏差,无法进行精确解算的问题,以人体静电电位信号采集试验的数据对齐操作为例,通过函数计算、波形分析、特征点提取等方法对3组不同传感器数据进行滤波清洗和对齐处理。结果表明,上述方法能够得到有效数据的起始点和终止点,解决数据采集过程中读取不同步的问题,提高了多传感器数据的对齐精度,为试验后续信号的识别提供更加准确的数据支持。所设计的数据对齐方法可应用于静电检测、运动健康、行为识别等具有多个传感器的数据采集系统中,为系统数据的对齐处理提供了有效的理论参考与方法依据。

电动助力转向系统回正力矩补偿控制

汽车在以不同车速行驶时,回正力矩变化显著会导致方向盘回正不足或回正超调。为了克服车速变化对汽车回正性能的影响,文中提出了基于回正力矩补偿的控制方法。在分析电动助力转向系统(Electric Power Steering System,EPS)数学模型和回正力矩模型基础上,基于车载电子稳定性程序传感器信号,提出通过方向盘转角确定期望回正力矩,由侧向加速度确定汽车的回正力矩。根据期望回正力矩和估计的实际回正力矩对EPS进行回正补偿,并对提出的控制算法在不同车速下进行仿真验证,结果表明:对于不同初始转角均具有良好的回正性能。

电吸收调制激光器EML的结对准工艺研究

阐述关键工序结对准工艺的实验研究,制备1310nm的EML器件。先使用电感耦合等离子体(ICP)进行表层材料刻蚀,通过优化刻蚀气体比例和功率等工艺参数,得到垂直度较高,表面光滑的刻蚀条件。接着使用InGaAsP选择腐蚀液,通过改变湿法腐蚀工艺的浓度配比和腐蚀条件,最终得到侧壁平滑的结构,为多次外延提供了基础。采用该结对准工艺制备的1310nm EML器件,室温下阈值电流为12mA,斜率效率为0.25W/A,100mA下的输出功率为22mW,消光比为13dB。

无人驾驶电机车多车斗同步自动对位装矿技术研究与应用

5G、云计算、AI等ICT技术飞速发展,为传统矿山提供了全新的发展机遇。矿山面临资源不足、开采难度递增、单位矿石生产成本高、未来劳动力风险大等关键的结构性问题,迫切需要数字化、智能化手段加以解决。原矿石窄轨运输是矿山开采的重要工艺,无人驾驶电机车的部署对是智能矿山建设意义重大,电机车无人驾驶中多车斗同步自动对位装矿是无人驾驶的重要环节,也是无人驾驶需要突破的技术难点。本次研究应用“激光传感器、激光雷达、AI视觉、射频信标、高精编码”等新技术的融合,完成多车斗同步自动对位装矿复杂工艺,能达到电机车无人驾驶目标及生产效率要求。