基于分布式风光互补电源直流充电装置设计

采用分布式风光互补发电系统作为充电电源,研究电动汽车蓄电池的快速充电问题。设计采用三阶段充电模式,即充电前期采用小电流预充电和脉冲充电相结合的快速充电方法,而在充电后期采用涓流补足充电法的直流充电装置对电动汽车蓄电池快速充电,以接触式银联卡作为介质收费。通过MATLAB仿真结果表明,设计的三阶段充电法的直流充电装置能对电动汽车蓄电池快速充电,并能自动收费。     

Contact electrification and adhesion between dissimilar materials

Simultaneous measurements of surface force and surface charge demonstrate strong attraction due to the spontaneous transfer of electrical charge from one smooth insulator (mica) to another (silica) as a result of simple, nonsliding contact in dry nitrogen. The measured surface charge densities are 5 to 20 millicoulombs per square meter after contact. The work required to separate the charged surfaces is typically 6 to 9 joules per square meter, comparable to the fracture energies of ionic-covalent materials. Observation of partial gas discharges when the surfaces are approximately 1 micrometer apart gives valuable insight into the charge separation processes underlying static electrical phenomena in general.     

空气介质阻挡放电等离子体对云南松单板表面的处理工艺

采用空气介质阻挡放电等离子体处理云南松单板表面,对处理后的单板进行胶合性能及表面性能分析,探讨放电等离子体处理单板表面的最佳工艺。结果表明：在1000—4000W范围,随处理功率的增加,单板的胶合强度增大,水接触角减小,表面能增大;在处理功率5000W时,各指标变化趋势相反。当处理次数为1—7次时,随处理次数的增加,单板的胶合强度增大,水接触角减小,表面能增大;在处理9、11次时,各指标变化趋势相反。当放电等离子体处理功率为4000W,处理次数为7次时,木材表面改性效果最佳,其胶合强度、水接触角及表面能分别为2．1MPa、43°、56．7MJ／m2。     

不同增温模式对卷烟加料效果的影响

[目的]考察不同增温模式对卷烟制丝生产加料效果的影响。[方法]为验证卷烟生产制丝过程中叶片加料工序前设置烟片增温(HT)工序的必要性和合理性,在"HT+叶片加料机"模式下,进行4种不同增温模式的试验。[结果]先利用HT对烟片进行增温、加料机无热风循环仅对烟片进行加料模式,加料机出口物料温度和含水率稳定性等方面优于其他加料模式,该模式下加料均匀性和料液的有效利用率最高,同时卷烟感官质量较好。[结论]试验为公司技改工艺设计打破传统的叶片加料工艺流程模式提供了技术支撑和依据。     

Study of electrization of powder skim milk during milk particle movement

Electrization of particles of powder materials is a widely spread phenomenon that makes a practical impact on the functional efficiency of equipment designed for producing a broad range of processed disperse products (dry milk, flour, grain, etc.). The results of electrization tests of powder skim milk particles are presented. A mathematical model of inner and outer transfer of electric charge for a single powder skim milk particle is suggested. The studies on a specialized laboratory unit have made it possible to obtain data on triboelectric charging of particles in different testing conditions.     

高校图书馆数字化资源收费问题探讨

高校图书馆对使用本馆内的数字化资源收取一定的费用,这在高校图书馆已经成为一种定式。文章通过对图书馆的收费原因、收费方式进行探讨,以度对如何管理这些费用提出一些合理化建议。     

氢氧化镍超级电容器电极材料储能性能研究

用水热法制备了氢氧化镍超级电容器电极材料,在对它的形貌、充放电电流等进行测试分析的基础上,应用速度反应理论,得到材料的充电电流强度和储能量与材料性质和充电时间等的关系.结果表明:材料的充电电流强度和储能量均随充电时间的增长而非线性地增大,其变化情况与反应物和生成物的化学势以及温度有关.理论与实验结果基本符合.     

铅酸蓄电池智能充电器控制策略研究

铅酸蓄电池智能充电需要解决电池快速充电和充电质量两个问题。提出了一种新颖的充电方法,容量跟踪脉冲电流-浮充充电方法。在控制器设计中提出了Fuzzy-PI控制器,通过Fuzzy控制器控制系统中频宽h,以同时保证充电系统快速性和动态过程稳定性。仿真与实验验证了上述设计的可行性。     

Box-Behnken 设计 - 响应面法优化感应静电喷雾参数

为了探究静电喷雾过程中多因素对荷质比的影响,采用感应荷电方式,先对4种孔径喷嘴的荷质比进行试验,选取一个荷质比变化较显著的喷嘴,然后采用单因素试验方法,分别对充电电压、喷雾压力、药液电导率3个因素进行试验,探讨各因素对荷质比的影响规律。在此基础上采用Box-Behnken设计-响应面法以TXVK-3型喷嘴的充电电压、喷雾压力、药液电导率进行3因素3水平的优化试验,确定最优参数。结果表明,在电压6.9 kV、喷雾压力0.3 MPa、药液电导率13.9 mS/cm时,平均荷质比为-0.227 mC/kg,相对误差不到2%。     

In situ observation of the electrochemical lithiation of a single SnO₂ nanowire electrode

We report the creation of a nanoscale electrochemical device inside a transmission electron microscope--consisting of a single tin dioxide (SnO(2)) nanowire anode, an ionic liquid electrolyte, and a bulk lithium cobalt dioxide (LiCoO(2)) cathode--and the in situ observation of the lithiation of the SnO(2) nanowire during electrochemical charging. Upon charging, a reaction front propagated progressively along the nanowire, causing the nanowire to swell, elongate, and spiral. The reaction front is a "Medusa zone" containing a high density of mobile dislocations, which are continuously nucleated and absorbed at the moving front. This dislocation cloud indicates large in-plane misfit stresses and is a structural precursor to electrochemically driven solid-state amorphization. Because lithiation-induced volume expansion, plasticity, and pulverization of electrode materials are the major mechanical effects that plague the performance and lifetime of high-capacity anodes in lithium-ion batteries, our observations provide important mechanistic insight for the design of advanced batteries.     

活性炭储氢系统充放气过程试验研究

为量化分析充放气压力和充放气流率对活性炭储氢系统充放气过程热效应的影响,选择比表面积为1800m2·g-1的椰壳活性炭SAC-01作吸附剂、容积为540mL的钢制压力容器为储存容器,在室温、4个压力（10．5MPa、8MPa、6MPa、4MPa）下,对容器进行氢的快速充放和通过质量流量控制器（MFC）设定气体流率下充放气试验．结果表明：在充放气的初始阶段,充放气流率较大,储罐中心温度在短时间内升高／降低到最大／最小值;储罐壁温度的变化特点与储罐中心的相似,但变化滞后且变化幅度较小．对比试验结果时发现,充放气流率一定时,充放气压力会影响吸附床的温度波动幅度,但不改变储罐中心上升／下降到温度幅值所需要的时间;充放气流率为影响吸附床温度波动的主要原因;采用慢速充放气可减缓吸附床的温度波动．     

纳米氧化铜表面超疏水膜的制备

通过控制氧化法在铜基底表面制得了氧化铜纳米花瓣膜,然后分别用十二烷基硬脂酸、硬脂酸、十二烷基硫醇和线性低密度聚乙烯对其表面进行修饰.结果表明:试验得到了超疏水复合膜,表面接触角均超过150°,滚动角小于5°.其中,十二烷基硫醇修饰时,可在短时间内(1h)得到疏水性较高的纳米复合膜,表面的接触角达到165°.通过晶型分析讨论纳米氧化铜的形成机理,并用X-射线粉末衍射(XRD)、接触角测量、表面反射红外光谱(IR)及扫描电子显微镜(SEM)对复合膜进行了表征分析,结果表明,试验成功制备了具有不同形貌的超疏水性纳米结构复合膜.     

Scanning Single-Electron Transistor Microscopy: Imaging Individual Charges

A single-electron transistor scanning electrometer (SETSE)-a scanned probe microscope capable of mapping static electric fields and charges with 100-nanometer spatial resolution and a charge sensitivity of a small fraction of an electron-has been developed. The active sensing element of the SETSE, a single-electron transistor fabricated at the end of a sharp glass tip, is scanned in close proximity across the sample surface. Images of the surface electric fields of a GaAs/AlxGa1-xAs heterostructure sample show individual photo-ionized charge sites and fluctuations in the dopant and surface-charge distribution on a length scale of 100 nanometers. The SETSE has been used to image and measure depleted regions, local capacitance, band bending, and contact potentials at submicrometer length scales on the surface of this semiconductor sample.     

基于城市特征差异性的充电设施规划

合理规划电动汽车充电设施,对推动电动汽车产业发展具有重要意义.为了使充电设施建设布局更加合理,提出了一种计及城市特征差异性的规划方法.依据城市各区域功能差异性进行板块划分,分析各板块用户充电需求特点;城市各道路交通状况也存在差异性,引入路况系数,提出时间成本模型;建立了一个以充电设施经济效益最大化为目标的规划模型,优化得到充电设施具体布局方案.算例分析表明:该方法得到了合理的充电设施规划方案,提高了充电设施经济效益,对重庆市充电设施的规划具有指导作用.     

Controlled atomic doping of a single C60 molecule

We report a method for controllably attaching an arbitrary number of charge dopant atoms directly to a single, isolated molecule. Charge-donating K atoms adsorbed on a silver surface were reversibly attached to a C60 molecule by moving it over K atoms with a scanning tunneling microscope tip. Spectroscopic measurements reveal that each attached K atom donates a constant amount of charge (approximately 0.6 electron charge) to the C60 host, thereby enabling its molecular electronic structure to be precisely and reversibly tuned.     

Generation of light from free electrons

Experiments with the interaction of a rectangular cross- section beam of electrons which is brought into contact with a metallic diffraction grat e ng produce light variable in wavelength throughout the visible spectrum. Con tinuous variation of the beam thickness shows that light is produced by electrons hundreds of wavelengths from the grating, if the side of the beam near the grating is in contact with it. The results can be accounted for by periodic accelerations of the electrons passing over the surface of the grating. These accelerations are caused by electrostatic forces which in turn are due to the average spacecharge of sheets of elec trons reflected from the grating surface, so that in their space- charge structure the periodicity of the grating rulings is preserved.     

Charge-induced reversible strain in a metal

Dimension changes on the order of 0.1% or above in response to an applied voltage have been reported for many types of materials, including ceramics, polymers, and carbon nanostructures, but not, so far, for metals. We show that reversible strain amplitudes comparable to those of commercial piezoceramics can be induced in metals by introducing a continuous network of nanometer-sized pores with a high surface area and by controlling the surface electronic charge density through an applied potential relative to an electrolyte impregnating the pores.     

Anomalous increase in carbon capacitance at pore sizes less than 1 nanometer

Carbon supercapacitors, which are energy storage devices that use ion adsorption on the surface of highly porous materials to store charge, have numerous advantages over other power-source technologies, but could realize further gains if their electrodes were properly optimized. Studying the effect of the pore size on capacitance could potentially improve performance by maximizing the electrode surface area accessible to electrolyte ions, but until recently, no studies had addressed the lower size limit of accessible pores. Using carbide-derived carbon, we generated pores with average sizes from 0.6 to 2.25 nanometer and studied double-layer capacitance in an organic electrolyte. The results challenge the long-held axiom that pores smaller than the size of solvated electrolyte ions are incapable of contributing to charge storage.     

Imaging coherent electron flow from a quantum point contact

Scanning a charged tip above the two-dimensional electron gas inside a gallium arsenide/aluminum gallium arsenide nanostructure allows the coherent electron flow from the lowest quantized modes of a quantum point contact at liquid helium temperatures to be imaged. As the width of the quantum point contact is increased, its electrical conductance increases in quantized steps of 2 e(2)/h, where e is the electron charge and h is Planck's constant. The angular dependence of the electron flow on each step agrees with theory, and fringes separated by half the electron wavelength are observed. Placing the tip so that it interrupts the flow from particular modes of the quantum point contact causes a reduction in the conductance of those particular conduction channels below 2 e(2)/h without affecting other channels.     

Quantum confinement and host/guest chemistry: probing a new dimension

Nanoparticulate metals and semiconductors that have atomic arrangements at the interface of molecular clusters and "infinite" solid-state arrays of atoms have distinctive properties determined by the extent of confinement of highly delocalized valence electrons. At this interface, the total number of atoms and the geometrical disposition of each atom can be used to significantly modify the electronic and photonic response of the medium. In addition to teh novel inherent physical properties of the quantum-confined moieties, their "packaging" into nanocomposite bulk materials can be used to define the confinement surface states and environment, intercluster interactions, the quantum-confinement geometry, and the effective charge-carrier density of the bulk. Current approaches for generating nanostructures of conducting materials are briefly reviewed, especially the use of three-dimensional crystalline superlattices as hosts for quantum-confined semiconductor atom arrays (such as quantum wires and dots) with controlled inter-quantum-structure tunneling.