Three-dimensional color particle image velocimetry based on a cross-correlation and optical flow method

Rainbow particle image velocimetry(PIV)can restore the three-dimensional velocity field of particles with a single camera;however,it requires a relatively long time to complete the reconstruction.This paper proposes a hybrid algorithm that combines the fast Fourier transform(FFT)based co-correlation algorithm and the Horn–Schunck(HS)optical flow pyramid iterative algorithm to increase the reconstruction speed.The Rankine vortex simulation experiment was performed,in which the particle velocity field was reconstructed using the proposed algorithm and the rainbow PIV method.The average endpoint error and average angular error of the proposed algorithm were roughly the same as those of the rainbow PIV algorithm;nevertheless,the reconstruction time was 20%shorter.Furthermore,the effect of velocity magnitude and particle density on the reconstruction results was analyzed.In the end,the performance of the proposed algorithm was verified using real experimental single-vortex and double-vortex datasets,from which a similar particle velocity field was obtained compared with the rainbow PIV algorithm.The results show that the reconstruction speed of the proposed hybrid algorithm is approximately 25%faster than that of the rainbow PIV algorithm.

Comparison of methods for vibration analysis of electrostatic precipitators

The paper presents two methods for the formulation of free vibration analysis of collecting electrodes of precipitators.The first,called the hybrid finite element method, combines the finit element method used for calculations of spring deformations with the rigid finite element method used to reflect mass and geometrical features,which is called the hybrid finite element method.As a result,a model with a diagonal mass matrix is obtained.Due to a specific geometry of the electrodes,which are long plates of complicated shapes,the second method proposed is the strip method which is a semi-analytical method.The strip method allows us to formulate the equations of motion with a considerably smaller number of generalized coordinates.Results of numerical calculations obtained by both methods are compared with those obtained using commercial software like ANSYS and ABAQUS.Good compatibility of results is achieved.

Modeling Technology in Finite Element Analysis of Electrostatic Proximity Fuze Problem

In order to analyze the electrostatic field concerned with electrostatic proximity fuze problem using the available finite analysis software package, the technology to model the problem with a scale reduction object and boundary was presented. The boundary is determined by the maximum distance the sensor can detect. The object model is obtained by multiplying the terms in Poisson's equation with a scale reduction factor and the real value can be reconstructed with the same reverse process after software calculation. Using the finite element analysis program, the simulation value is close to the theoretical value with a little error. The boundary determination and scale reduction method is suitable to modeling the irregular electrostatic field around air targets, such as airplane, missile and so on, which is based on commonly used personal computer (PC). The technology reduces the calculation and storage cost greatly.

STATIC STUDY OF CANTILEVER BEAM STICTION UNDER ELECTROSTATIC FORCE INFLUENCE

The model and analysis of the cantilever beam adhesion problem under the action of electrostatic force are given. Owing to the nonlinearity of electrostatic force, the analytical solution for this kind of problem is not available. In this paper, a systematic method of generating polynomials which are the exact beam solutions of the loads with di?erent distributions is provided. The polynomials are used to approximate the beam displacement due to electrostatic force. The equilibrium equation o?ers an answer to how the beam deforms but no information about the unstuck length. The derivative of the functional with respect to the unstuck length o?ers such information. But to compute the functional it is necessary to know the beam deformation. So the problem is iteratively solved until the results are converged. Galerkin and Newton-Raphson methods are used to solve this nonlinear problem. The e?ects of dielectric layer thickness and electrostatic voltage on the cantilever beam stiction are studied. The method provided in this paper exhibits good convergence. For the adhesion problem of cantilever beam without electrostatic voltage, the analytical solution is available and is also exactly matched by the computational results given by the method presented in this paper.

Analytical modeling of static behavior of electrostatically actuatednano/micromirrors considering van der Waals forces

In this paper, the effect of van der Waals （vdW） force on the pull-in behavior of electrostatically actuated nano/micromirrors is investigated. First, the minimum po- tential energy principle is utilized to find the equation gov- erning the static behavior of nano/micromirror under electro- static and vdW forces. Then, the stability of static equilib- rium points is analyzed using the energy method. It is found that when there exist two equilibrium points, the smaller one is stable and the larger one is unstable. The effects of dif- ferent design parameters on the mirror＇s pull-in angle and pull-in voltage are studied and it is found that vdW force can considerably reduce the stability limit of the mirror. At the end, the nonlinear equilibrium equation is solved numer- ically and analytically using homotopy perturbation method （HPM）. It is observed that a sixth order perturbation approx- imation can precisely model the mirror＇s behavior. The re- suits of this paper can be used for stable operation design and safe fabrication of torsional nano/micro actuators.

Model and Emulation of the System for the Passive Electrostatic Detecting People Through the Medium

The plane medium and point charge are regarded as an integral system. The static field＇s distribution situation of the point charge is studied in the medium structure of plane division layers by using mirror image method, drawing the point charge＇s calculation expression of the electric potential in every medium space. The mathematics model of passive electrostatic detecting people through the medium （regular distance between the goal point charge and the medium） is established, using MATLAB software to carry out emulation of the model and analysing the result, establishing the theoretical foundation for studying the technology of the passive static detecting people through the wall.

Lie algebraic analysis for the beam transport in the spherical electrostatic analyser

This paper uses the Lie algebraic method to analyse the charged particle trajectories in the spherical electrostatic analyser, and obtains the nonlinear solutions. The results show that the focusing abilities both in the x and y directions of the analyser are almost the same. Moreover, there exist dispersion effects in the x direction, and no dispersion effects in the y direction.

Asymmetric Electrostatic Force

Asymmetric electrostatic forces are a very interesting and new phenomenon. The magnitude of an electrostatic force that acts on a point charge does not change when the direction of the electric field is reversed. On the contrary, the magnitude of the electrostatic force that acts on a charged asymmetric shaped conductor does change when the direction of the electric field is reversed. 5 years ago, this phenomenon was reported by a simple experiment and a simulation and named as an Asymmetric electrostatic force unofficially by the author. After that, several simulations confirmed this phenomenon. However, several experiments did not yet confirm it clearly. The difference between the simulations and the experiments depends upon differences of their conditions. The simulations had been done under ideal (perfect) conditions;the experiments, on the contrary, had been done under actual (not perfect) conditions. In the new experiment, its conditions were improved to near ideal (perfect) conditions. As a result the existence of the Asymmetric electrostatic force was more clearly confirmed.

Effect of High-Frequency Electric Field on Propagation of Electrostatic Wave in a Non-Uniform Relativistic Plasma Waveguide

The effect of a high frequency （HF） electric field on the propagation of electrostatic wave in a 2D non-uniform relativistic plasma waveguide is investigated. A variable separation method is applied to the two-fluid plasma model. An analytical study of the reflection of electrostatic wave propagation along a magnetized non-uniform relativistic plasma slab subjected to an intense HF electric field is presented and compared with the case of a non relativistic plasma. It is found that, when the frequency of the incident wave is close to the relativistic electron plasma frequency, the plasma is less reflective due to the presence of both an HF field and the effect of relativistic electrons. On the other hand, for a low-frequency incident wave the reflection coefficient is directly proportional to the amplitude of the HF field. Also, it is shown that the relativistic electron plasma leads to a decrease in the value of reflection coefficient in comparison with the case of the non relativistic plasma.

Stochastic resonance in a gain-noise model of a single-mode laser driven by pump noise and quantum noise with cross-correlation between real and imaginary parts under direct signal modulation

Stochastic resonance （SR） is studied in a gain-noise model of a single-mode laser driven by a coloured pump noise and a quantum noise with cross-correlation between real and imaginary parts under a direct signal modulation. By using a linear approximation method, we find that the SR appears during the variation of signal-to-noise ratio （SNR） separately with the pump noise self-correlation time τ, the noise correlation coefficient between the real part and the imaginary part of the quantum noise λq, the attenuation coefficient γ＇ and the deterministic steady-state intensity I0. In addition, it is found that the SR can be characterized not only by the dependence of SNR on the noise variables of and λq, but also by the dependence of SNR on the laser system variables of γ and I0. Thus our investigation extends the characteristic quantity of SR proposed before.

Analysis for Pull-In Voltage of a Multilayered Micro-Bridge Driven by Electrostatic Force

A trial solution for bending deflection of a multilayered micro-bridge subject to a voltage induced load is presented. The relation between the applied voltage and the displacements of the micro-bridge in the pull-in state is analyzed by energy method. Furthermore, two analytical expressions about normalized displacement and pull-in voltage are carried out. It’s proved that the value of normalized displacement is not influenced by residual stress if axial and shear deformation is ignored. Finally, the theoretical results are compared with that of FEM, and they show good agreement.

First-Arrival Picking Method for Active Source Data with Ocean Bottom Seismometers Based on Spatial Waveform Variation Characteristics

The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction data.Traditional methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling interval.In this paper,a first-arrival picking method that utilizes the spatial waveform variation characteristics of active source OBS data is presented.First,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their waveforms.Second,a label cross-correlation superposition method for extracting highfrequency signals is presented to enhance the first-arrival picking precision.Results from synthetic and field data verify that the proposed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.

Template synthesis of copper azide primary explosive through Cu2O@HKUST-1 core-shell composite prepared by “bottle around ship” method

Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.

月面巡视器附近月尘静电迁移特性的数值模拟

针对月尘在月面巡视器附近的鞘层内的迁移和在设备表面的沉积过程开展数值模拟研究。首先,基于质点网格方法获得了巡视器附近的月表鞘层电场分布。在此基础上,分别探究了月表扬起月尘和静电悬浮月尘在鞘层电场内的迁移和在巡视器表面的沉积。研究表明,巡视器对鞘层电场的扰动作用增强了附近的电场,促进了月尘扬起和向巡视器表面的迁移沉积。当太阳天顶角较小或适中时,月尘只有达到临界行驶速度才能迁移至巡视器表面。

氧化石墨烯调控粉煤灰基硅酸锰/氧化锰复合材料的电化学性能机制

超级电容器是一种具有高功率密度、优秀循环性能、高安全性的高性能储能装置,然而其低能量密度限制其发展,为进一步提升超级电容器的能量密度,满足日益增长的储能需求,提升电极材料的电化学性能是关键。为提高粉煤灰基硅酸锰/氧化锰的电化学性能,采用静电组装法合成了氧化石墨烯与粉煤灰基硅酸锰/氧化锰的复合材料(FA@MS/MO/GO),通过调节氧化石墨烯加入量优化其电化学性能,并研究了氧化石墨烯对于粉煤灰基硅酸锰/氧化锰电化学性能的影响机制,通过XRD、SEM、XPS、FTIR表征材料的形貌与结构,并采用循环伏安法、恒电流充放电、交流阻抗测试对材料和器件性能进行测试。结果表明,优化后的FA@MS/MO/GO-2的电荷传输速率大幅提升,FA@MS/MO/GO-2在0.5 A/g电流密度下的比电容为737.4 F/g,高于未与氧化石墨烯复合的FA@MS/MO(293.4 F/g),电流密度由0.5 A/g升高至8.0 A/g,FA@MS/MO/GO-2容量保持率最好(67%),高于FA@MS/MO(44%)。FA@MS/MO/GO-2与商业活性炭分别为正负极组装为非对称超级电容器后,该器件能量密度达15.75 Wh/kg(功率密度375 W/kg),在5 A/g下循环10000次的容量保持率和库伦效率均可达100%,表明该电极材料拥有长期循环利用潜力,具有良好应用前景。

GB/T 39587-2020《静电防护管理通用要求》标准解析

静电防护的重要性不言而喻,尤其在工业生产和科研实验中,静电可能引发各种安全事故,深入理解并应用相关标准至关重要。GB/T 39587-2020《静电防护管理通用要求》为静电防护领域的重要通用标准,在体系构建、操作规范等方面有着显著的优势。本文旨在深入解析GB/T 39587标准,通过标准内容解读、特点分析,对比与其他管理标准差异等方面的阐述,为相关行业的静电防护管理工作提供理论支持和实践指导。文章对标准在未来静电防护管理中的应用提出了建议,以期推动静电防护管理水平的全面提升。

清瘟护肺颗粒化学成分研究

目的研究清瘟护肺颗粒的化学成分。方法查阅中国知网、PubMed、Web of Science等数据库,检索该制剂组方药材化学成分的相关文献,结合文献报道和ChemicalBook数据库信息,建立化学成分数据库。采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱(UHPLC-Q Exactive Focus MS/MS)法分析制剂的图谱数据,并以Xcalibur 4.0软件拟合分子式,与自建数据库信息进行匹配,初步推测分子式信息,与ChemicalBook或ChemSpider数据库比对,推测化学成分结构。结果共鉴定出158个化学成分,包括苷类36个,黄酮类29个,苯丙素类28个,有机酸类18个,萜类17个,色原酮类8个,其他类22个。结论所建立的方法可系统、准确、快速地定性分析清瘟护肺颗粒中的化学成分。

A novel measuring method of clamping force for electrostatic chuck in semiconductor devices

Electrostatic chucks are one of the core components of semiconductor devices. As a key index of electrostatic chucks, the clamping force must be controlled within a reasonable range. Therefore, it is essential to accurately measure the clamping force. To reduce the negative factors influencing measurement precision and repeatability, this article presents a novel method to measure the clamping force and we elaborate both the principle and the key procedure. A micro-force probe component is introduced to monitor, adjust, and eliminate the gap between the wafer and the electrostatic chuck. The contact force between the ruby probe and the wafer is selected as an important parameter to characterize de-chucking, and we have found that the moment of de-chucking can be exactly judged. Moreover, this article derives the formula calibrating equivalent action area of backside gas pressure under real working conditions, which can effectively connect the backside gas pressure at the moment of de-chucking and the clamping force. The experiments were then performed on a self-designed measuring platform.The de-chucking mechanism is discussed in light of our analysis of the experimental data. Determination criteria for de-chucking point are summed up. It is found that the relationship between de-chucking pressure and applied voltage conforms well to quadratic equation. Meanwhile, the result reveals that actual de-chucking behavior is much more complicated than the description given in the classical empirical formula.

多导体系统中静电场第二类、第三类边值问题的求解方法

静电场的第二类、第三类边值问题中通常给定导体的总电荷量,但由于导体面电荷密度分布未知,无法直接求解电场.本文根据静电场中导体电荷与电位的线性关系,将第二类、第三类边值问题转化为第一类边值问题,从而实现上述问题的求解.在此基础上,以平行双导线系统为研究对象,开展了静电场有限元仿真,验证了所提方法的有效性.

BTF-NC复合炸药的静电喷雾法制备及表征

【目的】为了解决苯并三氧化呋咱(benzotrioxafurazan,BTF)形貌不规则、易形成热点、机械感度较高的问题,通过对BTF进行降感处理已达到提高BTF的安全性能的目的。【方法】以BTF为主体炸药,硝化棉(nitrocellulose,NC)为黏结剂,采用静电喷雾法制备BTF-NC复合炸药;通过扫描电子显微镜、傅里叶变换红外光谱、同步热分析和机械感度仪对BTF-NC复合炸药样品的形貌、结构、热分解性能和机械感度进行分析和测试。【结果】BTF-NC复合炸药的粒径为400~2000 nm,颗粒呈现出球状或类球状;BTF-NC复合炸药中NC与BTF分子发生了键合;与原料BTF相比,BTF-NC复合炸药的热分解表观活化能降低了29.06 kJ/mol,自加速分解温度和热爆炸临界温度分别提高了1.3、4.21 K,失质量分数为89.41%,特性落高从23 cm增大至68.12 cm,爆炸分数由72%减小为24%;原料BTF和BTF-NC复合炸药的吉布斯自由能变均为正值;原料BTF与NC的相容性等级为1级。【结论】采用静电喷雾技术制得的BTF-NC复合炸药的热安定性、机械感度均得到显著改善。