An Accelerated Simulation Method for ELDRS of Bipolar Operational Amplifiers Using a Dose-Rate Switching Experiment

Through different dose-rate switching evaluation methods,the radiation-response rules of operational amplifiers are studied when the irradiation dose rate is switched from high to low under different radiation temperatures and total doses. The experimental results indicate that the response characteristics could be affected by the switching total doses, irradiation temperatures,and dose rates individually or together. Accelerated evaluation on the ELDRS can be realized by adopting a proper dose-rate switching method. Meanwhile, the irradiation time can also be reduced. Finally, the mechanisms of the difference between various radiation responses are analyzed.

Switching variability index based multiple strategy CFAR detector

A switching variability index （SVl） constant false alarm rate （CFAR） detector is proposed for improving the detection performance of VI-CFAR detectors in multiple targets backgrounds. When the presence of non-homogeneity in CFAR reference windows is indicated by a VI-CFAR detector, a switching- CFAR detector is introduced to optimize the performance of the VI-CFAR detector in homogeneous, multiple targets and clutter edge backgrounds. The structure and parameters selection method of the SVI-CFAR detector is presented. Comparisons with classic CFAR detectors and recently proposed detectors are also given. Theoretical analysis and simulation results show that SVICFAR detector maintains the good performance of the VI-CFAR detector in homogeneous and clutter edge backgrounds, while greatly improving the capacity of anti-multi targets.

A Novel Dual-Rate Sampling Switched-Capacitor Configuration and Its Application

In order to realize accurate bilinear transformation from s- to z-domain,a novelswitched-capacitor configuration is proposed in the light of principles of dual-rate sampling and chargeconservation,which has also been used for building a 5th-order elliptic lowpass filter.The filter issimulated and measured in typical 0.34 μm/3.3 V Si CMOS process models,special full differentialoperational amplifiers and CMOS transfer gate switches,which achieves 80 MHz sampling rate,17.8MHz cutoff frequency,0.052 dB maximum passband ripple,42.1 dB minimum stopband attenuation and74 mW quiescent power dissipation.At the same time,the dual-rate sampling topology breaks thetraditional restrictions of filter introduced by unit-gain bandwidth and slew rate of operational amplifiersand also improves effectively their performances in high-frequency applications.It has been applied forthe design of an anti-alias filter in analog front-end of video decoder IC with 15 MHz signal frequencyyet.

基于排序的自动剔除Switching-CFAR检测器

针对传统恒虚警(Constant False-Alarm Rate,CFAR)检测器在非均匀噪声环境下检测性能较差的问题,本文提出了一种基于排序的自动剔除Switching-CFAR(Automatic Censoring Switching-CFAR Detector Based on Sorting,ACS-CFAR)检测器.选择参考窗中间单元为测试单元,其余单元按照幅值升序排列,根据两个分界点位置参数,选择合适的参考单元集进行背景噪声功率估计以及结合参考单元数和目标恒虚警率计算相关系数,得到最优检测门限.经过仿真对比,ACS-CFAR检测器在均匀噪声环境下检测率为98.73%,接近于单元平均恒虚警(CA-CFAR)检测器;在非均匀噪声环境下检测率为98.16%,优于可变索引恒虚警(VI-CFAR)和自动删除平均恒虚警(ACCA-CFAR)检测器,虚警率误差均控制在0.10%以内.结果表明,本文提出的ACS-CFAR检测器在均匀噪声环境以及杂波和多目标干扰环境下均具有较好的检测性能.

Experimental Study of the Recovery Times of Spark Gap Switch with Different Gases

A two-pulse method is used to determine the insulation recovery time of the gas spark gap switch with different types of gas applied in a high power accelerator with a water dielectric pulse forming line. At the breakdown voltage of 450 kV, with the vacuum diode voltage of about 200 kV, and a current of 30 kA, recovery characteristics of H2, N2, SF6 were studied. The recovery percentages of the gas breakdown voltage and vacuum diode voltage were determined. The results show that hydrogen has the best recovery characteristics. At a pulse interval of 8.8 ms, the recovery percentages of both the gas breakdown voltage and vacuum diode voltage for hydrogen exceed 95%. For SF6 and N2 with an interval of 25 ms and 50 ms respectively, a 90% voltage recovery was obtained. The experiments also proved that the repetitive rate of the high power accelerator with a pulse forming line is mainly restricted by the gas switch repetitive rate; the recovery percentages of the vacuum diode voltage are limited by the recovery percentages of the gas switch breakdown voltage. The hydrogen switch can be employed for a high repetitive rate-high power accelerator with a pulse forming line.

Modelling of passively Q-switched lasers with intracavity Raman conversion

We present a model of passively Q-switched Raman lasers by utilizing the rate equations. The intracavity fun-damental photon density, Raman photon density and the initial population-inversion density of the gain medium are assumed to be of Gaussian spatial distributions. These rate equations are normalized by introducing some synthetic parameters and solved numerically, and a group of general curves are generated. Prom these curves we can understand the dependence of the Raman laser pulse characteristics on the parameters about the pumping, the gain medium, the Raman medium and the resonator. An illustrative calculation for a passively Q-switched Nd^3＋：GdVO4 self-Raman laser is presented to demonstrate the usage of the curves and related formulas.

A theoretical and experimental investigation of an in-band pumped gain-switched thulium-doped fiber laser

In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber （TDF） laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.

Simulation of the Physical Performance of Optical Packet Switching Nodes

A graphical and visual simulation system for the study of optical packet switching (OPS) nodes is accomplished. With the simulation system, the effect on physical performance-bit error rate (BER) due to a variety of factors such as the crosstalk parameters of OPS nodes, number of cascaded OPS nodes, length of optical output buffer, traffic load and fluctuation of amplitude of optical signals are evaluated. Reliability of the simulation system is proved by the analytical results obtained in all the above cases.

A Network Calculus Approach for the Analysis of Packet-switching Networks

Network calculus is an evolving new methodology for backlog and delay analysis of packet-switching networks. With network calculus we are able to compute tight bounds on delays,backlogs,and effective bandwidths in a lossless setting applicable to packet-switching networks and better understand some physical properties of networks. In this paper,the basic network calculus concepts of arrival curves and service curves are introduced.Then we provide the approach for modeling leaky-bucket,generic cell rate algorithm(GCRA),constant bit rate(CBR)flow, variable bit rate(VBR) flow with arrival curve.It is shown that all rate-based packet schedulers can be by a simple rate latency service curve.And by applying these fundamental rules of network calculus,bounds on delay, buffer,effective bandwidth for leaky bucket,GCRA,CBR and VBR can be derived and some practical examples are given.Finally,we compare all the results obtained and conclude this paper.

气体火花间隙开关通道电阻及热效应特性研究

针对一种应用于高功率重复频率Marx型脉冲功率源的两电极火花间隙气体开关,开展了火花通道电阻及其热效应特性研究,分析了火花间隙通道电阻热效应的影响因素,研究了重复频率连续工作条件下开关腔体内温度及气压变化。研究结果表明,开关腔体内气压和温度随着工作时间增长呈现先快速增加然后缓慢增长趋于稳定的趋势,脉冲电流幅值的增长对热量沉积的增加效果非常明显。研制的两电极火花间隙开关,在导通峰值电流14.7 kA、脉冲宽度160 ns的条件下连续运行9000个脉冲时,开关通道产生热量约36.6 kJ,在电流导通时间内,通过焦耳热效应计算得到开关导通时间内火花通道电阻平均值约0.12Ω。

蝴蝶优化算法对大青杨生长速率预测模型的改进

为提高大青杨生长速率的预测精度,提出了一种基于改进的蝴蝶优化算法(improved butterfly optimization algorithm, IBOA)与径向基函数(radial basis function, RBF)神经网络结合的预测木材材性方法。通过使用佳点集法对标准蝴蝶算法中的种群进行初始化,将自适应切换频率和Levy飞行相结合进一步优化人工蝴蝶算法。构建出了新的IBOA-RBF神经网络木材材性预测模型,将得到的结果与其他几种算法优化的RBF神经网络预测结果进行对比。结果表明:基于IBOA-RBF神经网络模型预测效果最好,收敛速度从37步降低到了23步,预测结果误差达到了5.72%,预测精度最高。可见,对蝴蝶算法的改进是可行的,且对相关人员定向培养大青杨起到较大的帮助。

左乙拉西坦品牌药转为非专利药后对癫痫患儿的临床疗效和不良反应分析

目的前瞻性观察左乙拉西坦(LEV)由品牌药转换为非专利药后对癫痫患儿的临床疗效和不良反应变化。方法以2019年4月至2020年12月在西安交通大学第二附属医院儿科就诊的196例癫痫患儿为研究对象,收集其从LEV品牌药转换为非专利药治疗前后的临床资料,并根据转换后疾病发作情况分为发作增加组、发作减少组及发作无变化组。分析转换前后各组LEV血药浓度、癫痫发作情况、不良反应及转换后发作增加患儿的临床特征。结果转换前LEV血药浓度为(8.09±2.42)μg/mL,转换后血药浓度为(8.28±2.17)μg/mL,经比较差异无统计学意义(t=0.521,P=0.831)。转换前LEV治疗剂量/血药浓度比值为(3.44±1.10)L/kg,转换后治疗剂量/血药浓度比值为(3.77±1.59)L/kg,经比较差异无统计学意义(t=0.723,P=0.762)。转换前LEV的治疗有效率为81.05%(154/190),转换为非专利药后有效率为75.79%(144/190),经比较差异无统计学意义(χ^(2)=1.555,P=0.212)。发病年龄小及联合治疗的患儿在转换后可能会出现发作增加,LEV品牌药转换为非专利药后,未见出现新的不良反应。结论LEV品牌药转为非专利药后对癫痫患儿治疗安全有效,对发病年龄小及联合治疗的患儿需要重点关注。

高速铁路道岔的大修周期

基于高速道岔钢轨及弹性铁垫板的部件劣化规律,提出高速道岔大修周期建议。结果表明:高速道岔混凝土岔枕及无砟轨道设计使用寿命较长,大修应以成组更换道岔钢轨及联结零件为主;成组更换道岔曲外股钢轨应以辙叉翼轨侧面磨耗达到8 mm重伤限值为准,宜按照维修进行更换。成组更换道岔钢轨的周期为通过总质量450~900 Mt或服役时间19~45年,更换道岔弹性铁垫板的周期宜定为20年。建议高速道岔成组更换钢轨及联结零件的大修周期定为年通过总质量600 Mt或服役时间20年,且应根据道岔实际状态评估后决定是否列入大修计划。

LTD多间隙气体开关低概率自放电估计

开关触发前发生的低概率自击穿故障,是制约直线变压器驱动源(LTD)技术发展和工程应用的主要因素。针对多间隙气体开关的自放电概率展开研究,设计了简化结构的气体开关来测量更高气压下的自击穿电压;推导了考虑间隙分压不均的开关自击穿电压累积分布函数,计算LTD工作气压下的多间隙开关自击穿电压分布特性并进行实验验证;通过超越阈值方法对低工作系数下的小概率自放电事件进行威布尔分布拟合,得到自放电概率估计值;对气体开关开展了万发次考核实验,得到自放电概率测量值。结果表明:开关的自击穿电压分散性随着气压升高而增加,测量低气压下的自击穿电压无法外推得到实际工作高气压条件下的自放电概率;开关工作系数为65%和60%时,气体开关的自放电概率估计值为1:44×10^(-4)和3:01×10^(-5),与开关万发次考核的实验结果相近,验证了估计方法的可行性。

一种pH沉淀-溶解切换除油剂的制备及性能评价

以十四胺和1,3-丙磺内酯为原料,通过磺化反应合成pH沉淀-溶解切换除油剂十四烷基胺基丙磺酸钠(TMPS),经FTIR、ESI-MS和1H NMR对其结构进行了表征。以表面张力法测定了其临界胶束浓度为1.332×10^(-3)mol/L,γcmc为26.93 mN/m。用5号白油浸润的石英砂作为模拟油砂,通过单因素实验,确定了TMPS对油砂的最佳清洗条件为:除油剂浓度15 mmoL/L,温度65℃,料液比1∶5,清洗时间60 min,搅拌速度1000 rad/min。在该条件下对油砂除油效果可达96.41%,循环5次后仍保持良好的除油效果达80%以上。通过对比除油剂回收前后的核磁氢谱,结构没有变化,能有效解决油基钻屑除油过程中除油剂的浪费。

四能级模型声光调Q CO_(2)激光器理论数值模拟

声光调Q CO_(2)激光器因其具有特定波长传输效率理想、光束聚焦性能好、连续功率高、输出脉冲大等特点,被广泛应用在激光测距、生产加工、空间通信、光谱学、环境探测、雷达成像领域中。文章考虑声光损耗情况下基于四能级模型给出了声光调Q CO_(2)激光器速率方程,在一定条件下通过离散迭代的方式对该速率方程组进行数值模拟,分析了声光调Q CO_(2)激光器的运行特性,以在生产研究中更好地使用、设计CO_(2)激光器。

Simulation of Diode-Pumped Q-Switched Nd:YAG Laser Generating Eye-Safe Signal in IOPO Environment

Numerical simulation of diode-pumped Q-switched Nd:YAG laser leading to the generation of eye-safe signal in singly resonant Intracavity Optical Parametric Oscillator (IOPO) is presented. Starting from rate equations, the time dependent laser equations have been solved numerically, whereas the space-dependent OPO equations analytically. Our results show that 1.4 J diode laser (810 nm) pulse with 200 msec width, delivers 30 mJ Nd:YAG laser (1064 nm) pulse with 5 n-second width. This Nd:YAG laser further generates 9 mJ eye safe signal (1570 nm) pulse with 2.5 n-second width.

考虑移动储能的风雨灾害配电网弹性提升方法

以台风和暴雨为代表的极端自然灾害会导致配电网大规模故障。为减小故障损失,提出一种计及风雨联合灾害下考虑移动储能的配电网弹性提升方法。首先,量化台风和暴雨灾害对配电网造成的影响,构建风雨联合灾害下的配电网故障率模型并基于系统信息熵筛选典型故障场景;其次,以灾害期间切负荷经济损失最小为目标,建立混合整数二阶锥规划模型,提出计及弹性提升的移动储能运行调度方法;最后,通过仿真算例对所提方法的有效性进行验证。结果表明,本文所提方法能有效提升配电网弹性,减少停电带来的经济损失。

浅谈PLC PID回路切换的稳定控制

PID控制器是工业自动化控制领域中应用最为广泛的一种算法控制器,在各种工业控制器上都集成有PID控制功能实现温度、压力等物理量的控制。主要讨论液压系统的流速和压力闭环控制和两种控制之间的切换,控制对象是液压伺服比例阀。工艺要求先流速控制再切换到压力控制,在项目后期调试过程中,两个PID回路的切换时刻,需要通过一种控制方法实现液压伺服比例阀的稳定控制。

交换机流量限制技术及其在智能变电站的应用

交换机具备的流量限制和风暴抑制功能,在智能变电站网络中具有重要的应用价值。在分析智能变电站网络结构、报文类型和流量特征基础上,论述了过程层网络化带来的问题和解决思路。介绍了现有交换机风暴抑制功能及其不足,提出了智能变电站网络流量限制应具备的功能。基于交换机数据处理流程,详细分析了基于内容感知处理器(CAP)的流量限制技术及其特点。通过搭建智能变电站三网合一网络仿真测试环境,验证了基于CAP的流量限制方案,并展望其在智能变电站的应用前景。