Static electric dipole polarizability of lithium atoms in Debye plasmas

The static electric dipole polarizabilities of the ground state and n ≤ 3 excited states of a lithium atom embedded in a weekly coupled plasma environment are investigated as a function of the plasma screening radium. The plasma screening of the Coulomb interaction is described by the Debye-Hiickel potential and the interaction between the valence electron and the atomic core is described by a model potential. The electron energies and wave functions for both the bound and continuum states are calculated by solving the SchrSdinger equation numerically using the symplectic integrator. The oscillator strengths, partial-wave, and total static dipole polarizabilities of the ground state and n ≤ 3 excited states of the lithium atom are calculated. Comparison of present results with those of other authors, when available, is made. The results for the 2s ground state demonstrated that the oscillator strengths and the static dipole polarizabilities from np orbitals do not always increase or decrease with the plasma screening effect increasing, unlike that for hydrogen-like ions, especially for 2s→3p transition there is a zero value for both the oscillator strength and the static dipole polarizability for screening length D = 10.3106a0, which is associated with the Cooper minima.

Frequency domain wave equation forward modeling using gaussian elimination with static pivoting

Frequency domain wave equation forward modeling is a problem of solving large scale linear sparse systems which is often subject to the limits of computational efficiency and memory storage. Conventional Gaussian elimination cannot resolve the parallel computation of huge data. Therefore, we use the Gaussian elimination with static pivoting （GESP） method for sparse matrix decomposition and multi-source finite-difference modeling. The GESP method does not only improve the computational efficiency but also benefit the distributed parallel computation of matrix decomposition within a single frequency point. We test the proposed method using the classic Marmousi model. Both the single-frequency wave field and time domain seismic section show that the proposed method improves the simulation accuracy and computational efficiency and saves and makes full use of memory. This method can lay the basis for waveform inversion.

Measurement-based approach for identification of static load model of electric power system

The validity of electric power system simulation or prediction models depends on static load model. Measurement- based approach is the unique method to identify them adequately. The measured power depends on both load reaction to supply voltage alteration and random process of load alteration Basically, there is no any universal method that can single out the inherent static load model from experimental data. The paper offers a proprietary technique which is the particular solution of the task. The technique considers the selection of neighboring measurement pairs with the supply voltage altering significantly be-tween them, the exclusion of selected pairs by load power factor and subsequent selection of the inherent static load model presented as the polynomial load model. The usage of the technique to identify static load model at “Fenster” industrial enterprise （in Borisov city） is presented. The ideas considered in the paper can be used for future development of static load model identification methods with the data obtained during both active experiment and in other operating models of electric power systems.

GaN-based heterostructures： electric-static equilibrium and boundary conditions

In the GaN-based heterostructures, this paper reports that the strong electric fields induced by polarization effects at the structure boundaries complicate the electric-static equilibrium and the boundary conditions. The basic requirements of electric-static equilibrium for the heterostructure systems are discussed first, and it is deduced that in the application of the coupled Schroedinger-Poisson model to the heterostructures of electric static equilibrium state, zero external electric field guarantees the overall electric neutrality, and there is no need to introduce the charge balance equation. Then the relation between the screening of the polar charges in GaN-based heterostructures and the possible boundary conditions of the Poisson equation is analysed, it is shown that the various boundary conditions are equivalent to each other, and the surface charge, which can be used in studying the screening of the polar charges, can be precisely solved even if only the conduction band energy is correctly known at the surface. Finally, through the calculations on an AlGaN/GaN heterostructure with typical structure parameters by the coupled Schroedinger-Poisson model under the various boundary conditions, the correctness of the above analyses are validated.

Research on the Static Magnetic Field of Ships with Corrosion and Anticorrosion Efficacy Using Electric Dipole Model

In the case of three-layered(air-seawater-seabed)model,the analytical expressions of the static electric and static magnetic field produced by the static electric dipole located in seawater were derived by using the mirror image theory.Combined with the distribution of the underwater electric potential measured in laboratory,an electric dipole model for physical scale of ship was established and the distribution characteristics of an actual ship' s corrosion related magnetic field were obtained.Based on established models,theoretical analysis and calculation were made to catch out the distribution characteristics of static magnetic field related with corrosion and anticorrosion,which can not be measured directly in seawater.The results show that the static magnetic field related with corrosion and anticorrosion is a kind of noteworthy obstacle signal for degaussed ships.

Saturated sodium chloride solution under an external static electric field: A molecular dynamics study

The behavior of saturated aqueous Na Cl solutions under a constant external electric field（E） was studied by molecular dynamics（MD） simulation. Our dynamic MD simulations indicated that the irreversible nucleation process towards crystallization is accelerated by a moderate E but retarded or even prohibited under a stronger E, which can be understood by the competition between self-diffusion and drift motion. The former increases with E, thereby accelerating the nucleation process, whereas the latter pulls oppositely charged ions apart under a stronger E, thereby decelerating nucleation.Additionally, our steady-state MD simulations indicated that a first-order phase transition occurs in saturated solutions at a certain threshold Ec. The magnitude of Ec increases with concentration because larger clusters form more easily when the solution is more concentrated and require a stronger E to dissociate.

Variation of Two-photon Absorption Cross Sections and Optical Limiting of Compounds Induced by Static Electric Field

By numerically solving the Maxwell-Bloch equations using an iterative predictor-corrector finite-difference time-domain technique, we investigate propagating properties of a few-cycle laser pulse in a 4,4＇-bis（di-n-butylamino） stilbene （BDBAS） molecular medium when a static electric field exists. Dynamical two-photon absorption （TPA） cross sections are obtained and optical limiting （OL） behavior is displayed. The results show that when the static electric field intensity increases, the dynamical TPA cross section is enhanced and the OL behavior is improved. Moreover, both even- and odd-order harmonic spectral components are generated with existence of the static electric field because it breaks the inversion symmetry of the BDBAS molecule. This work provides a method to modulate the nonlinear optical properties of the BDBAS compounds.

Static Electric-Spring and Nonlinear Oscillations

The author designed a family of nonlinear static electric-springs. The nonlinear oscillations of a massively charged particle under the influence of one such spring are studied. The equation of motion of the spring-mass system is highly nonlinear. Utilizing Mathematica [1] the equation of motion is solved numerically. The kinematics of the particle namely, its position, velocity and acceleration as a function of time, are displayed in three separate phase diagrams. Energy of the oscillator is analyzed. The nonlinear motion of the charged particle is set into an actual three-dimensional setting and animated for a comprehensive understanding.

高压氧舱恒湿平压系统的设计

目的:设计一种高压氧舱恒湿平压系统,以消除舱内静电火花造成的危害,保证氧舱的安全运行。方法:该系统的硬件主要由加湿装置、除湿装置、平压装置、主控制器、压力传感器、温湿度传感器等组成。其中,加湿装置主体为经过特殊加工后的防爆过滤瓶;除湿装置采用工业级风机过滤单元(fan filter unit,FFU),由蒸发器、冷凝器、风轮3个部分组成;平压装置主要由电磁阀和减压管路组成;主控制器选用EX3G-C系列PLC触摸屏一体机,温湿度传感器选用NWSF-1AT型号温湿度传感器,压力传感器选用TXYS-G1K2HN3型变送器。系统的软件控制程序采用指令表语言编程,通过PID(proportional-integral-derivative)控制算法实现整体控制。结果:经过测试,该系统可使高压氧舱内相对湿度恒定在70%,使舱内极难产生静电。结论:该系统能够调节氧舱内的湿度、减少静电火花产生,保证舱内治疗的安全。

计及电池老化特征的电动公交车静态无线充电设施布局优化

为解决既有静态无线充电(Static Wireless Charging,SWC)设施布局方案容易忽略电池老化成本的问题,提出了计及电池老化特征的电动公交车SWC设施布局优化方法。首先考虑机会充电模式下电动公交车的运行特征,建立兼顾充电设施布设成本与电池老化成本的SWC设施布局优化模型,将电池荷电状态变化区间对电池老化速率的作用机理融入模型,同时引入累积能耗约束以确保SWC设施布局方案满足公交线路运营需求;然后针对模型的计算复杂性,提出一种改进禁忌搜索(Tabu Search,TS)算法对模型进行求解,依据模型特点构造算法的初始解及邻域结构;最后设计数值算例对模型和算法进行验证。研究结果表明:SWC设施布局对电池老化具有显著影响,相比不考虑电池老化特征的常规模型,文中提出的模型可以使年均总成本降低3.8%;在现阶段电池技术与成本条件下,电池老化成本占年均总成本的比例高达72.3%;文中提出的改进TS算法较原始TS算法在求解效率上有显著提升。文中还通过灵敏度分析探讨了模型的多个关键参数对优化结果的影响,发现电池荷电状态值上界、SWC设施充电功率与年均总成本呈显著的负相关,而电池单位容量成本、SWC设施布设成本、车辆单位行驶能耗与年均总成本呈不同程度的正相关。

炭黑/废纸导电纤维的制备及其在聚丙烯中的应用

利用多巴胺氧化自聚合将炭黑粘附到废纸纤维表面,制备了炭黑/废纸柔性导电纤维,分析了炭黑含量对纤维导电性能的影响,然后,将该导电纤维与聚丙烯熔融共混制备复合材料,分析了导电纤维添加量对复合材料导电和力学性能的影响。结果表明,聚多巴胺将炭黑均匀粘附在废纸纤维表面,纤维的电阻率随着炭黑含量增加而逐渐降低,当炭黑含量为15%时,废纸纤维的电阻率logρ下降至2.16Ω·cm。柔性导电纤维能更好地控制聚丙烯复合材料电导率降低幅度,当纤维添加量为15%(炭黑含量为2.27%)时,复合材料的表面电阻率为3.71×10^(10)Ω,体积电阻率为2.45×10^(11)Ω·cm,能达到抗静电级别。此时,复合材料的弹性模量和拉伸强度分别为565.65和17.01 MPa,模量提高了1.07%,但强度降低了32.82%。

背压扰动平衡盘对涡旋压缩机黏性内流压力影响研究

在变转速工况下,电动涡旋压缩机背压腔中润滑油产生的背压力无法准确平衡轴向气体力。针对这一问题,提出了一种带有扰动片的背压扰动平衡盘,研究了背压扰动平衡盘对涡旋压缩机黏性内流压力的影响。首先,对背压扰动平衡盘作用原理进行了分析,使用贝塞尔曲线构建了扰动片型线,对润滑油被扰动后的静压增量进行了公式推导,计算了扰动片出口安装角和扰动片数对润滑油静压的影响;然后,建立了含背压扰动平衡盘的背压腔模型,将流体域分为旋转域和静止域,采用旋转坐标系的方法进行了数值模拟,研究了背压腔内润滑油的压力场;最后,根据理论计算,模拟了润滑油在不同出口安装角和扰动片数下的润滑油静压,对润滑油静压与压缩机所需最佳背压进行了对比分析。研究结果表明:采用背压扰动平衡盘可以使润滑油静压增加21%,且静压增量随主轴转速的增加而增大,适当增大扰动片出口安装角可使润滑油静压增加0.032 MPa;对比最佳背压可知,扰动前润滑油静压与最佳背压相差26%,而合理设计扰动片后的润滑油静压与最佳背压相差仅为9%,极大改善了电动涡旋压缩机在变转速下的轴向平衡。

防静电环氧地坪涂料导电矿物材料

静电产生的电磁波危害工作生活,因此需要性能良好的静电防护材料。本研究综合分析了静电防护涂料中导电材料的特点和防静电机理。以防静电环氧地坪涂料为例,分析静电防护材料中的导电矿物材料,重点分析了导电金属抗静电涂料、浅色抗静电涂料、碳系抗静电涂料中导电矿物材料。以碳系抗静电涂料为主,分析了决定防静电性能的导电材料的成分、结构和性能。在此基础上,探讨抗静电地坪涂料导电矿物材料的发展趋势,探索能够防护静电的高性能抗静电地坪涂料。与传统导电材料相比,碳石墨矿物材料具有明显优势。采用石墨矿物为原料合成的石墨烯碳添加少量就能大幅提高环氧树脂的电导率,获得优异的防静电效果。深入研究导电矿物微观结构特点,在分子原子层次上进行纳米结构组装,有可能开发出高性价比的抗静电涂料,提高电子仪表、医药等行业生产生活洁净场所的防静电水平。

电动挖掘机落物保护装置拓扑优化设计

针对某型电动挖掘机的乘员防护,提出使用基于等效静态载荷法的拓扑优化方法设计落物保护装置(Falling Object Protective Structures,FOPS)。首先,使用基于位移等效原则的等效静态载荷法,将动态非线性碰撞过程简化为多工况条件下的静态非线性变形过程。随后,提出使用加权系数法,将动态非线性拓扑优化简化为多工况条件下的静态非线性拓扑优化,可显著提高拓扑优化的计算速率和收敛性。最后,基于拓扑优化结果设计FOPS,并按照GB/T 17771—2010进行仿真试验分析。结果表明,新设计的FOPS无须额外加强即可满足乘员落物保护要求,且FOPS的总质量减轻了49.8 kg,这对降低工程机械的采购和使用成本,以及满足节能减排具有积极意义。

基于源码分析的自动化外部函数接口生成方法

外部函数接口(FFI)是解决一种编程语言调用其他语言函数库的主要方法。针对使用FFI技术时需要大量人工编码的问题,提出自动化外部函数接口生成(AFIG)方法。该方法利用基于抽象语法树的源码逆向分析技术,从被封装的库文件中精准提取出用于描述函数接口信息的多语言融合的统一表示。基于此统一表示,不同平台的代码生成器可利用多语言转换规则矩阵,全自动化地生成不同平台的FFI相关代码。为解决FFI代码生成中的效率低下问题,设计了一种基于依赖分析的任务聚合策略,通过把存在依赖的任务聚合为新的任务,有效消除了FFI代码任务在并行下的阻塞与死锁,从而实现任务在多核系统下的可扩展与负载均衡。实验结果表明:与人工编码相比,AFIG方法减少了FFI开发中98.14%的开发编码量以及41.95%的测试编码量;与现有的SWIG(Simplified Wrapper and Interface Generator)方法相比,在同等任务下可减少61.27%的开发成本;且生成效率随着计算资源的增加呈线性增长。

蔬菜育苗高压静电吸附播种机理及系统参数优化

针对现有气吸式穴盘育苗播种机对含杂较多且没有丸粒化的不规则小颗粒蔬菜种子存在吸孔堵塞而导致排种精度下降的技术难题,该研究摒弃小孔径、长导程吸孔,设计了一种基于高压静电吸附特性的蔬菜育苗播种机。通过理论分析及电势等值线分布仿真试验确定介电绝缘层材料;构建静电吸附力学模型,明确影响静电吸附力的主要因素及其相互关系,确定影响播种性能的电参数及范围;以型孔加工直径、正向高压静电发生器输出电压和种箱底面倾斜角度为试验因素,以播种合格指数、重播指数和漏播指数为响应指标进行三因素三水平Box-Behnken中心组合试验,得到各试验因素与响应指标间的数学模型,应用Design-Expert 10.0.4软件对数学模型进行多目标优化,得到最佳参数组合为:型孔加工直径5.91 mm、正向高压静电发生器输出电压17.67 kV、种箱底面倾斜角度14.69°,此时播种合格指数为91.13%、重播指数为3.02%、漏播指数为5.85%。播种性能验证试验的播种合格指数相较于优化结果降低了0.61个百分点、重播指数相较于优化结果降低了0.17个百分点、漏播指数相较于优化结果增加了0.78个百分点。试验误差在允许范围内,参数优化结果可靠,满足精量播种技术要求。研究结果可为不规则小颗粒蔬菜种子精量播种机械装备的研发提供参考,同时也可为不规则小颗粒物料定量吸附和快速分离方法研究及设备开发提供参考。

聚烯烃颗粒在气力输送中静电起电特性研究

为了探究不同聚烯烃粉体颗粒在气力输送过程中起电特性,采用一套自制气力输送实验系统,探究了气力输送过程中不同气固浓度参数对PETG、PP、ABS这3种聚烯烃颗粒静电起电特性的影响规律。结果表明:气力输送过程中PETG与PP颗粒带负电荷,ABS颗粒带正电荷,质量流量和输送空气速度对PETG、PP颗粒的荷质比变化呈类似的变化规律,而ABS颗粒的规律则有所不同。随着颗粒质量流量增大,PETG和PP分别表现为总负电荷量减小;而相同质量流量条件下ABS颗粒则表现为总正电荷量增加。随着输送空气速度增加,3种聚烯烃颗粒所带电荷也会增加,但PETG和PP颗粒电荷极性则会出现极大值。

外加静电场对O_(2)分子高次谐波的调制机制(特邀)

采用了Lewenstein强场近似方法,计算了外加静电场对O_(2)分子在线偏振激光场中高次谐波产生的影响。结果表明:1)当静电场方向平行激光偏振方向时,谐波谱出现双平台结构,截止频率增大,偶次和奇次谐波幅度相当;2)当静电场方向垂直时,谐波谱呈现单平台结构,偶次谐波比奇次谐波的幅度小两个量级左右;3)外加静电场对双心干涉极小值的位置基本没有影响。利用Lewenstein理论,可以将分子谐波谱视为分子两端电离通道产生谐波的叠加,对外加静电场控制高次谐波提供了参考。

工业级芯片热管理与漏电流阈值设定技术

工业级芯片因为高温应用环境的需求,对芯片封装的热管理提出了更高的要求。芯片的漏电流随温度的升高而呈指数级增大的特点,导致高温静态功耗成为影响芯片结温的关键因素,因此有必要在优化动态功耗的基础上,进一步管控静态功耗。基于不同温度下的晶圆漏电流测试,建立了芯片常温漏电流与高温总功耗的关系,提出了基于芯片结温阈值的常温漏电流筛选机制。搭建了芯片热测试实验平台,验证了漏电流筛选的准确性。实现了基于常温的晶圆测试来快速准确地剔除在高温下总功耗超标的芯片,对提高工业级芯片的良率及质量具有重要意义。

热挤压和脉冲电流对AZ91镁合金及其复合材料显微组织和力学性能的影响

为探究SiC_(p)对AZ91镁合金在电脉冲处理过程中组织和性能演变规律的影响,通过在AZ91合金中添加1%(体积分数)微米级SiC_(p)制备了SiC_(p)/AZ91复合材料,联合低温正挤压和电脉冲处理对AZ91合金和SiC_(p)/AZ91复合材料的组织进行细化,利用光学显微镜分析显微组织的演化,测试合金和复合材料的室温力学性能。结果表明,和AZ91合金相比,添加了增强相颗粒后的复合材料挤压之后具有更高的位错密度和形变储存能,从而促进电脉冲处理时的静态再结晶过程。电脉冲处理后的AZ91合金及复合材料的屈服强度和抗拉强度分别为320、450 MPa和380、454 MPa。由于SiC_(p)与镁基体界面处应力集中而形成的微裂纹,导致复合材料抗拉强度增幅较小。