高温度稳定性腔体滤波器研究

本文从腔体尺寸角度出发,认为某一方向的尺寸随温度是线形变化的.推导出了腔体各个部件的温漂影响因子,该因子反映了腔体的某个部件对整个腔体的温漂影响的大小.用三维仿真软件HFSS和CST去计算部件温漂影响因子,所得结果基本一致.建立了抵消温漂的模型,由该模型出发合理设计腔体各部分材料,得出无温漂的腔体.用经过温补的腔体设计出了高温度稳定性的滤波器.     

内置介质板开孔腔体电磁屏蔽效能拓扑模型

文中针对现有内置介质板腔体屏蔽效能拓扑模型中介质板等效导纳模型的局限性,考虑介质板高度、厚度与位置对介质板等效导纳模型的影响,建立内置介质板腔体屏蔽效能(BLT)方程拓扑模型。将传输线法、BLT方程拓扑模型与仿真结果进行对比,验证BLT方程拓扑模型的准确性和有效性。以300 mm×300 mm×120 mm开孔腔体为研究对象,分别探究其在3种不同谐振主模式下,介质板高度、厚度和位置对腔体屏蔽效能的影响。结果表明,改变介质板高度,腔体的谐振主模式不变,仅影响腔体屏蔽效能大小;腔体内部安装介质板可增强腔体屏蔽能力,但是介质板厚度过大,在一定范围内会削弱腔体屏蔽能力;距腔体孔阵0 mm～58 mm处安装介质板会削弱腔体屏蔽能力,距腔体孔阵100 mm～150 mm处安装介质板会增强腔体屏蔽能力。该结论可为机箱电磁屏蔽设计提供有效参考。     

快速预测干扰下斜开孔腔体屏蔽效能的模型

提出一种针对复杂干扰下斜开孔金属腔体屏蔽效能的计算模型。该模型可快速精准地计算出任意金属材料腔体,任意开孔位置,任意观测点位置,任意入射、极化平面波照射以及斜开孔阵腔体的屏蔽效能。首先依据磁流原理和镜像原理将斜开孔腔体等效为两个水平开孔腔体,然后基于Robinson的等效电路法分别求解各自的屏蔽效能,再利用公式换算求得斜开孔金属腔体的屏蔽效能。随后针对腔体会面临的不同干扰,给出不同情况下屏蔽效能的计算方法。考虑多种干扰叠加的复杂工况,将该模型利用Matlab 进行编程,并将计算结果同全波仿真软件CST中的时域传输线矩阵法和频域有限元法的仿真结果进行对比,验证了所提模型的可行性。该模型在保证计算精度的同时,在计算效率上表现出极大的优势。     

SF200综合数字式音频扫频仪

1引言 现在多媒体音响的低音炮音箱腔体主流有2种：倒相式腔体和一阶带通式腔体。后者比前者难度更大一些。要设计出一个全新的低音炮音箱腔体是比较复杂和困难的，音箱制成后需用昂贵仪器设备测试箱体阻抗特性曲线与扬声器阻抗特性曲线是否相匹配，再对扬声器或箱体参数进行反复调整，最后才能得到一个较好的方案，其开发周期较长。     

等离子清洗机的腔体设计

介绍了等离子的产生机理及等离子清洗技术的原理；给出一种等离子清洗机的腔体，其特点是工艺气体从左向右水平流动，每个带有小孔的腔体极板可以灵活配置成悬浮极、阳极和阴极；选取合适的工艺条件后，获得了良好的清洗效果。     

大腔体器件气密性焊接技术研究

阐述了大腔体器件的储能焊焊接技术，讨论了焊接基本要素，建立了焊接能量模型。分析了影响气密性的主要因素，通过改进焊接技术和优化工艺参数，解决了大腔体器件的气密性焊接技术问题。目前，大腔体器件(150—200mm周长，对角线≤70mm)气密性焊接的成品率已达到93％。     

雷电脉冲透射非规则圆柱腔体耦合分析

针对雷电间接效应圆柱腔体耦合场表征中透射方法在非规则圆柱腔体情况下误差较大的问题,在规则圆柱腔体透射场原理分析的基础上,对Richard时域转移阻抗模型进行调整,提出基于腔体表面曲率半径的时域转移阻抗模型。该模型考虑了腔体半径变化的影响,能同时有效表征规则圆柱腔体和非规则圆柱腔体的时域转移阻抗。在验证试验中成功地将非规则圆柱腔体透射场与内部场的误差从10.83%缩小到4.9%,解决了透射法在非规则圆柱腔体雷电场耦合中的适用性问题。本文工作为雷电脉冲透射非规则圆柱腔体耦合分析提供一个适用范围更广的方法。     

基于频率变换的双通带腔体滤波器的研究

该文基于频率变换的方法设计了两种结构的双通带的腔体滤波器,一种是通过谐振器之间直接耦合实现的;另一种是在谐振器之间引入交叉耦合实现的,从而达到产生传输零点的目的。首先根据设计指标,采用频率变换的方法,计算得到谐振器间的耦合系数和外部Q值,然后利用Ansoft HFSS建立同轴腔体滤波器的模型并进行仿真,仿真结果与ADS中等效电路得到的理论结果基本吻合,从而验证了这种方法的正确性。最后通过对级联型结构与交叉耦合型结构双通带腔体滤波器的比较,得出后者比前者具有更好的带外抑制特性。     

基于核机器学习的腔体滤波器辅助调试

 研究了一种基于核机器学习的腔体滤波器辅助调试方法.该方法根据工程中的调试经验数据,首先使用核机器学习算法建立了螺栓调整量和滤波器电性能之间的影响关系模型.然后应用此模型,使用优化技术构建了滤波器的辅助调整方法.实际滤波器的实验结果表明了该方法的有效性.该方法比较适用于工程中批量生产的腔体滤波器的辅助调试.     

基于BLT计算复杂腔体结构屏蔽效能的拓展方法

本文通过拓展BLT(Baum-Liu-Tesche)方法,计算了复杂结构腔体的屏蔽效能（Shielding Effectiveness,SE）. BLT方法最初被用于分析传输线模型,后被拓展到计算腔体屏蔽效能,然而其局限于计算矩形腔体和圆柱腔体的屏蔽效能,无法分析更加复杂的腔体结构.本文将BLT方法与数值方法相结合,同时利用机器学习的回归方法,将其拓展到复杂腔体结构的屏蔽效能计算中.本文首先计算了腔体二维截面的特征模;然后,基于电磁波传播规律建立了等效电路网络结构,结合BLT方法获得腔体屏蔽效能的频域响应分布;最后,利用机器学习方法训练支持向量回归模型（Support Vector Regression,SVR）,修正频域响应幅值,得到腔体目标的屏蔽效能.本文采用了3种不同结构的腔体对提出的方法进行了验证,频率范围为0.1～3 GHz.以商业软件仿真得到的结果为标准,本文提出的方法可以在85%的置信度条件下,实现均方根误差小于3,同时计算速度相比商业软件提升80倍以上.     

Effect of the inlet location on the performance of parallel-channel cold-plate

This study numerically examines the influence of inlet locations on the performance of the Multichannel cold-plates. A total of five inlet configurations (namely I-, Z-, ]-, L-, and /spl Gamma/-arrangement) are investigated in this study. The velocity maldistribution and nonuniformity of temperature field caused by the fluid flow are shown in the simulation. For I-arrangement, higher inlet flow rate of the cold-plate shows more considerable maldistribution, and this maldistribution is decreased when the number of channels of the cold-plate is increased. The Z-arrangement and L-arrangements show a pronounced flow-recirculation that eventually leads to a much larger temperature difference along the surface of the cold-plate. Conversely, there is no flow recirculation in the ]-arrangement and a comparatively uniform flow distribution is seen. For the same average inlet velocity, I-arrangement has the highest pressure drop whereas ]-arrangement shows the lowest pressure drop. The I- and /spl Gamma/-arrangement give the best heat transfer performance due to their impingement configurations whereas the Z-arrangement shows the lowest heat transfer performance for its dramatic flow recirculation and maldistribution.     

计算腔体散射的GRE—FDTD混合方法

在飞机雷达截面（RCS）的理论预估中，飞机进气道的电磁散射计算是其难点之一。对于厘米波段雷达而言，进气道属于电大尺寸目标，而其终端一般还存在涡轮叶片之类的复杂结构，单用高频近似方法难以解决。本文介绍GRE－FDTD混合方法可用于进气道的电磁散射计算。该方法用广义射线展开法（GeneralizedRayExpansion，GRE）计算进气道前端的缓变部分，用时域有限差分法（FDTD）计算包括涡轮叶片的复杂结构段。计算结果与波导模式法（Modal）－炬量法（MoM）混合方法的结果相比较，二者有很好的一致性。     

主喷管总温对MGDL小信号增益系数的影响

在国内外数值模拟工作的基础上,建立了更加准确的"混合型气动CO2激光器(简称MGDL)"增益场计算程序。利用该程序,一方面研究了基于筛形喷管的混合型气动CO2激光器光腔中的小信号增益分布规律;另一方面着重研究了主喷管入口总温对基于筛形喷管的混合型气动CO2激光器小信号增益系数的影响规律。计算结果表明:当其他参数不变时,主喷管入口总温存在一个最佳值,使得光腔中的小信号增益系数最大;当主喷管入口总温小于这个最佳值时,随着主喷管入口总温的增加,光腔中相同位置处的小信号增益系数逐渐增大;当主喷管入口总温大于这个最佳值时,随着主喷管入口总温的增加,光腔中相同位置处的小信号增益系数逐渐减小。此外,分析了主喷管入口总温对小信号增益系数的影响机制。     

进出口位置对槽道流体分配和换热的影响

针对平行小槽道的流量分配问题,设计了不同的进出口方式,并采用数值方法研究其对槽道散热器内流量分配和换热特性的影响。结果表明,进出口方式对槽道散热器内流量分配特性影响很大;提出流量和换热不均匀系数来评价进出口方式的影响,发现相同进出口方式下,流量不均匀系数随着流量的增大而增大;当槽道散热器流量相同时,顶部中间(UC)进出口形式的散热器内流量不均匀系数最小;当槽道面积一定时,流量不均匀系数随槽道个数增加而减小;流量一定时,槽道的表面温度不平均系数随加热功率的上升而增加;加热功率一定时,热阻随着流量的增加逐渐减小并趋于定值。     

Study on the fluid/structure interaction at different inlet pressures in molded packaging

This paper presents the computational study of fluid/structure interaction (FSI) analysis in the molding process using the Mesh-based parallel Code Coupling Interface (MpCCI) method with finite volume coding (FLUENT 6.3) and finite element coding (ABAQUS 6.9). The FSI analysis is implemented on the molded package during the encapsulation process with different inlet pressures. Real-time flow visualization, deformation and stress of the silicon die during the encapsulation process are presented in this paper. A fluctuation phenomenon of the silicon die is found in the encapsulation process when the inlet pressure increases. The maximum deformation during the process is determined at different locations on the silicon die, calculated during the final stage of the filling process. The deformation and stress of the die is exponentially increased with increasing inlet pressure. The maximum stress on the solder bump is concentrated near to the inlet gate. Thus, the present FSI analysis approach is expected to be a guideline or reference and provides better understanding of the encapsulation process for package design in the microelectronic industry.     

一种并行真实进气道RCS计算方法

进气道是飞行器头部方向3大强散射源之一,目前国际上工程实用的算法主要以射线法为主,射线法在解决大长径比、大S弯进气道时误差较大,难以满足工程中进气道隐身方案设计的需求。文中选用精度较高的迭代物理光学法,采用快速多极子方法对面元之间的相互影响进行加速,辅以基于MPI的并行技术,在32节点计算平台上模拟了真实进气道尺寸大小的腔体X波段的RCS,计算结果和模式法结果吻合良好,验证了该方法具有真实进气道X波段RCS预估能力。     

Electromagnetic scattering from simple jet engine models

The mode-matching (MM) technique is employed for the evaluation of the radar cross section (RCS) of structures that simulate a jet engine inlet. The geometry consists of a perfectly conducting cylindrical inlet terminated by an array of blades mounted on a cylindrical hub. Comparisons of numerical results with actual measurements are presented for the first time     

Focusing of biological cells utilizing negative dielectrophoretic force generated by insulating structures

The main purpose of the present study is to design an insulator-based dielectrophoretic microdevice with effective focusing of biological cells. The cells are introduced into the microchannel and pre-confined hydrodynamically by the funnel-shaped insulating structures close to the inlet. The cells are, therefore, repelled toward the center of the microchannel by the negative dielectrophoretic forces generated by the insulating structures. The increase in the applied electric field significantly enhances the performance of focusing. Furthermore, decreasing inlet velocity increases the efficiency of focusing because the higher velocity results in more lateral expansion. Preliminary experiments employing viable HeLa cells are conducted in order to demonstrate the feasibility of the present design. Experimental results indicate that the performance of focusing increases with the strength of the electric field applied or with a decrease in the inlet velocity. The experimental results agree with the predictions by numerical simulations. The design proposed herein has no need for complicated flow controls to focus the cells.     

基于混沌理论的主风机组风险预警研究

在外界各种条件下,石油催化裂化系统主风机组烟机进口温度易受到影响,从而在一定温度范围内产生波动,这种特征表现与混沌特性相似.为了验证石油催化裂化系统主风机组烟机进口温度具有混沌特性,进而通过Lyapunov指数计算方法来判断.利用C-C方法对其数据序列进行了相空间重构.采用一种稀疏Volterra滤波器对主风机组烟机进口温度进行混沌预测.结果显示：在一定的条件下,稀疏Volterra滤波器能够优化有效的滤波系数,减少滤波系数的个数,使其数量减到最少,并保持预测精度不变,降低了预测模型的复杂性.     

Optimal design methodology of plate-fin heat sinks for electronic cooling using entropy generation strategy

This paper presents a formal systematic optimization process to plate-fins heat sink design for dissipating the maximum heat generation from electronic component by applying the entropy generation rate to obtain the highest heat transfer efficiency. The design investigations demonstrate the thermal performance with horizontal inlet cooling stream is slightly superior to that with vertical inlet cooling stream. However, the design of vertical inlet stream model can yield to a less structural mass (volume) required than that of horizontal inlet stream model under the same amount of heat dissipation. In this paper, the constrained optimization of plate-fins heat sink design with vertical inlet stream model is developed to achieve enhanced thermal performance. The number of fins and the aspect ratio are the most responsive factors for influencing thermal performances. The heat sink used on AMD Thunderbird 1-GHz processor has been examined and redesigned by presenting optimization methodology. The optimal thermal analysis has a very good agreement to the both of vendors' announced information and using simulation of parabolic hyperbolic or elliptic numerical integration code series (PHOENICS). The optimum design that minimizes entropy generation rate in this paper primarily applied three criteria for plate-fins heat sink optimal design: formal constrained nonlinear programming to obtain the maximum heat dissipation; prescribed heat dissipation; prescribed surface temperature. As a result, the thermal performance can be notably improved; both the sink size and structural mass can apparently be reduced through the presented design method and process. This analysis and design methodology can be further applied to other finned type heat sink designs.