Research on Performance of U Separator in Sand and Dust Test System

Sand/dust test is one of the key projects to examine the environmental adaptability of ordnance equipment.In order to decrease the abrasion of test facility caused by the sand/dust particles,the particles contained in the airflowneed to be reclaimed effectively.Amathematical model of Useparator is established.The flowfield and the trajectories of particles inside the separator are obtained using a numerical simulation method,and the separation efficiency and pressure drop of separator with different rows of separate components are also obtained at various flowvelocities.The simulation results indicate that the efficiency of U inertia separator is affected by the flowvelocity evidently,and a reasonably designed separator can meet the requirement of the separation efficiency in particular situation.The results can be use as reference for the design and test of sand/dust separate systems.     

光纤传感系统中APD增益温漂的动态补偿研究

为实现对雪崩光电二极管(APD)增益温漂的动态偏压补偿, 设计了高精度的ADC和DAC电路系统,对APD可以达到毫伏级的偏压控制精度和0.2 ℃的温度采样精度.依托光纤传感系统并运用数据采集与处理技术获得了在APD增益比较稳定的条件下其偏压与温度之间的线性关系以及增益温漂误差的偏压补偿公式,应用时传感系统能够实时补偿增益的温漂并且具有足以满足系统要求的补偿精度.     

一种新型的漂移阶跃恢复二极管脉冲源设计

提出了一种基于漂移阶跃恢复二极管（DSRD）、结构简单的新型大功率脉冲源电路.论述了阶跃恢复二极管的快速开关特性,分析了该新型脉冲源电路的工作原理,并进行了实验测试.实验结果表明,脉冲源电路能够产生峰峰值为760 V、脉宽（10％-10％）8 ns的平衡输出脉冲信号,具有脉冲重频高、振铃小、波形质量高、无需高压供电等特点,适用于深层探测超宽带时域脉冲探地雷达系统.     

一种基于ART2神经网络的算法改进

针对传统的ART2神经网络中对于主观设置的警戒参数以及识别分类过程中产生模式漂移的问题,提出基于改进算法的ART2神经网络模型,用于解决分析模式识别问题。通过自组织,加权,迭代等过程推导合理的警戒参数用于聚类运算,通过对ART2神经网络的权值训练方面进行修正,减缓学习速率,降低模式漂移速度,近一步对聚类对象进行合理分类。实验结果证明,该方法是可行的和有效的。     

一种高精度低温漂振荡器设计

针对无线通信和微机械传感器系统对时钟相位噪声的要求,设计了一种高精度低温漂的振荡器电路设计。利用Leeson线形相位噪声模型分析相位噪声,降低了主要噪声源,达到优化相位噪声的目的。该电路在华润上华018 μm工艺平台上流片验证。测试结果显示,电源电压在22~36 V变化,温度在-35~85 ℃变化,频率变化为-2％～+05％;相位噪声-116 dBc＠1 kHz;4 000个周期的抖动在-12%～+12%。该电路已成功集成到微机械陀螺仪控制芯片中。     

压力传感器零点电漂移与热漂移特性的模拟

利用ＰＳＰＩＣＥ程序结合非线性电阻模型来模拟压力传感器的电桥电路,可显示零点电漂移和热漂移特性。并阐明可利用电漂移来消除热零点漂移。     

造型材料表观热物性的测定

为精确地模拟铸件的凝固过程和进行铸造工艺的计算机辅助设计,采用浇注法对粘土砂和水玻璃砂的表观热物性进行了研究。实验表明,型砂的表观导热系数、表观导温系数及表观蓄热系数均随着原砂粒度的增大而增大,也随着粘结剂的含量(陶土或水玻璃)增加而增大,但达到一定程度后则趋于恒定。     

冷硬树脂砂在球墨铸铁和铸钢件上的应用

介绍了冷硬树脂砂在该厂球墨铸铁和铸钢件上的应用。     

铁型覆砂铸造球墨铸铁曲轴

介绍了铁型覆砂铸造球墨铸铁曲轴的工艺,并就推广应用中发现的铸造缺陷提出了防止措施.     

Estimation of power density in IMPATT using different materials

ABSTRACT

The RF output power dissipated per unit area is calculated using Runge-Kutta method for the high-moderate-moderate-high (n⁺-n-p-p⁺) doping profile of double drift region (DDR)-based impact avalanche transit time (IMPATT) diode by taking different substrate at Ka band. Those substrates are silicon, gallium arsenide, germanium, wurtzite gallium nitride, indium phosphide and 4H-silicon carbide. A comparative study regarding power dissipation ability by the IMPATT using different material is being presented thereby modelling the DDR IMPATT diode in a one-dimensional structure. The IMPATT based on 4H-SiC element has highest power density in the order of 10¹⁰ Wm^?2 and the Si-based counterpart has lowest power density of order 10⁶ Wm^?2 throughout the Ka band. So, 4H-SiC-based IMPATT should be preferable over others for the power density preference based application. This result will be helpful to estimate the power density of the IMPATT for any doping profile and to select the proper element for the optimum design of the IMPATT as far as power density is concerned in the Ka band. Also, we have focused on variation of power density with different junction temperatures and modelled the heat sink with analysis of thermal resistances.