HO 6/10/25-P系列电流传感器

正莱姆电子为HO系列的PCB直插式电流传感器增加了三个新产品。HO 6、10和25-P系列产品的零点漂移和增益漂移是前一代产品精度的两倍(温度范围:-25~+85℃)。由于电间隙和爬电距离大于8mm,以及CTI600(相对漏电起痕指数),增加了原边和副边之间的绝缘水平,测试隔离电压达到4.3kVRMS/50Hz/1分钟。     

具有“芯 - 壳”及纳米畴结构的 X9R 型钛酸钡基陶瓷介电性能研究

高容高温是下一代片式多层陶瓷电容器的重要发展方向,因此,开发具有高容高温特性的 X9R 型钛酸钡基介质材料,对于促进高容高温多层陶瓷电容器的发展具有重要意义。该研究以钛酸钡(BaTiO 3 ,BT)为原料,利用传统固相反应烧结法,并通过调节钛酸铋钠(Bi 1/2 Na 1/2 TiO 3 ,BNT)的基体固溶量和稀土元素铌(Nb)的掺杂量,成功制备出具有较高室温介电常数和较宽容温特性的 Nb 掺杂 BT-BNT 介质体系。在此基础上,对 X9R 型介质材料纳米畴及“芯-壳”结构与介温特性之间的关系进行了研究。实验结果表明,当 BNT 固溶量为 10 mol%,BT-BNT 的居里温度为 190 ℃,晶粒具有典型的 90°铁电畴;在 0.9BT-0.1BNT 固溶体中掺杂 2.0 mol% 的 Nb 元素,介电常数为 1 800,损耗 ＜2.0%,容温系数(－55～200 ℃) ≤ 15%,晶粒形成明显的“芯-壳”结构,其中 “芯”部具有小尺寸的纳米尺度铁电纳米畴,“壳”部为 Nb 均匀分布的 BT-BNT 固溶体。因此,0.9BT-0.1BNT-2.0Nb 陶瓷是一种极具前景的 X9R 型多层陶瓷电容器用电介质材料。     

压电陶瓷电特性测试与分析

通过对压电陶瓷器件进行阻抗测试可得到压电振子等效电路模型参数与谐振频率。通过对压电陶瓷器件电容值、温度稳定性、绝缘电阻、介质耐电压等电性能参数进行测量与分析后可知:压电陶瓷器件电特性符合一般电容器特点,所用连接线材在较低频率下寄生电容不明显,在常温下工作较稳定,厚度较厚的产品绝缘性和可靠性指标较好。     

用Protel绘制简单的PCB图

印刷电路板(Printed Circuit Board,简称PCB)在电子设备中是一种不可缺少的部件。它以绝缘板为基材,以铜箱为导线,实现了电路中元器件的固定和电气连接。所以,制作印刷电路板是电子爱好者把自己的设想变为现实的重要环节。而PCB图设计的好坏也将直接影响到电路功能的发挥、工作的稳定性和可靠性。用Protel软件设计PCB图,可以提高设计质量,节省时     

压阻式微加速度计灵敏度的温度特性研究

以压阻式微加速度计为研究对象,定量研究了环境温度对其灵敏度的影响。理论研究结果表明,压阻式微加速度计灵敏度的相对误差随着温度偏差绝对值的增大而增大;其中灵敏度误差在温度偏差为 20℃时达到-4.943%,在温度偏差为-20℃时达到4.982%。设计了压阻式微加速度计压敏电阻的温度特性测试系统,测试结果表明,在温度偏差为 20℃时,灵敏度误差为-4.303%,温度偏差为-20℃时,实验值为4.251%。理论计算值与实验测试值相吻合。     

微型线圈-铁芯结构传感器中聚酰亚胺的低成本刻蚀和平坦化方法

本文研究了预亚胺化温度、时间以及刻蚀时间对聚酰亚胺湿法刻蚀结果的影响。预亚胺化后 2.5 μm厚的PI-5型聚酰亚胺采用EPG 533型光刻胶作为掩膜时,预亚胺化采用90℃/5 min - 140℃/10 min方案,采用1% KOH溶液,15 s的显影/刻蚀时间会得到较好的刻蚀结果。在此基础上,通过实验研究了一种低成本的填充式平坦化技术。通过在底层线圈上旋涂一层聚酰亚胺,湿法刻蚀去除铜线上的聚酰亚胺保留间隙中聚酰亚胺,然后再旋涂第二层聚酰亚胺的方式,完成了第二层聚酰亚胺的平坦化。与直接在底层线圈上旋涂聚酰亚胺而不做平坦化处理比较,起伏高度差从1.8 μm降低到150 nm,且起伏缓慢、无明显台阶。应用这种技术制备了一种采用线圈铁芯结构的微型磁通门传感器并进行了测试,传感器工作正常,性能优良。     

振动式微陀螺正交误差自补偿方法

微陀螺正交误差会影响陀螺的零偏稳定性,为了提高微陀螺的性能,必须减小正交误差。针对正交误差处理中存在的问题,推导了包含交叉耦合误差效应的驱动模态和检测模态的动力学方程,研究了交叉耦合误差引起的正交误差表达式,提出了一种正交误差闭环控制自补偿方法。通过将经正交误差幅值调幅控制的驱动位移信号闭环反馈作用到检测模态的输出,实现正交误差的自补偿。制作PCB电路测试了微陀螺的性能。正交误差自补偿后微陀螺零偏输出均值从778 mV减小到了2 mV,零偏稳定性从75°/h提高到了34.5°/h。实验结果表明,此方法是可行的。     

以聚苯胺表面包覆钛酸钡作为填料的环氧复合材料的微观结构与介电性能

通过原位聚合的方法合成了表面包覆钛酸钡的聚苯胺复合纳米颗粒(BT@PANI),并将该复合纳米颗粒作为填料制备了具有特殊结构的BT@PANI/EP三相复合材料。实验发现由于导电聚苯胺增强了界面极化,因此随着BT@PANI中PANI质量的增加(即BT在复合材料中的质量分数减少),该复合材料的介电常数也随之增加。当PANI的质量分数从0%增加至26%时,其介电常数也从17提高到了53,并且当BT@PANI中PANI的质量分数达到26%时,该复合材料并没有出现明显的渗流效应,且其导电率保持在1.64×10-6 S/m这一较低值。此外,当测量温度范围在60℃到100℃之间时,该复合材料的介电常数发生了明显的上升,这一现象可以说明随着温度的上升,导电聚苯胺、环氧分子链在Tg温度(90℃)下运动增强及钛酸钡在居里温度(120℃)下的相变共同产生了强烈的界面极化。     

转动极板悬空设计的数字电容角位移传感器及其温度特性测试

在比例式电容测角原理的基础上,设计了一种转动极板为金属材质且为电气悬空设计的数字型角位移传感器,满足180°的测量范围.该传感器具有本质可靠性,无需额外补偿环节,即可对环境温度,潮湿,灰尘等共模干扰具有良好的抑制作用.针对快速变化的温场,进行了基于该原理的角位移传感器的温度特性测试.在环境温度从-15℃升到 65℃,以约6℃/分钟速度变化的过程中,三台样机的最大峰峰值温漂值为0.085%/10℃,实验周期内的最大稳态温漂值为0.07%/10℃,标准不确定度小于0.1%,在以同样温变速度进行的-30℃～ 80℃的宽温实验中,最大峰峰值温漂值小于0.2%/10℃.结果表明,其温漂指标优于目前基于差动测量原理的主流产品.     

RF MEMS电容式开关结构层释放技术

研究了RF MEMS开关的制造工艺流程和聚酰亚胺牺牲层的去除工艺。在开关的设计和加工中采用在信号线两侧的地线上生长一层绝缘介质层,直流偏置线生成在绝缘介质层之上,与桥的锚点相连接,实现了交直流隔离。讨论了干法刻蚀和湿法刻蚀牺牲层技术。干法刻蚀容易造成绝缘介质层的刻蚀和损伤。采用湿法刻蚀结合临界点干燥技术,可以获得理想的微梁结构。通过测试,开关样品的下拉电压为34 V～40 V,下拉距离为(1.7±0.2)μm,满足设计要求。     

M/G/c/K blocking probability models and system performance

An exact solution for the M/G/c/K model is only possible for special cases, such as exponential service, a single server, or no waiting room at all. Instead of basing the approximation on an infinite capacity queue as is often the case, an approximation based on a closed-form expression derivable from the finite capacity exponential queue is presented. Properties of the closed-form expression along with its use in approximating the blocking probability of M/G/c/K systems are discussed. Extensive experiments are provided to test and verify the efficacy of our approximate results.     

设计模式变体的描述与验证*

为解决标准设计模式演化后难以检测的问题,引入设计模式变体思想,以Bridge模式为例,给出了八种常用的变体实现,并以人工形式挖掘了四种开源系统中Bridge模式变体的基准数,接着在Apache Ant1.6.2与JHotDraw5.1开源系统中通过六种主流设计模式检测工具进行了变体检测实验。试验结果表明,FCA-CBR方法简单有效,对2种开源系统中Bridge模式变体检测的精确率达到60%与48.1%,与先前方法相比有了较大的提高。     

(r∞, n12, s12) measurements on the 2-CPU CRAY X-MP

We report performance measurements made on the 2-CPU CRAY X-MP at ECMWF, Reading. Vector (SIMD) performance on one CPU is interpreted by the two parameters ($\text{r}{}_{\mathrm{\infty }}\text{, n}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$), and we find for dyadic operations using FORTRAN $\text{r}{}_{\mathrm{\infty }}\text{= 70}\text{Mflop/s}\text{, n}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 53}\text{flop}$. All vector triadic operations produce $\text{r}{}_{\mathrm{\infty }}\text{= 107}\text{Mflop/s}\text{, n}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 45}\text{flop}$; and a triadic operation with two vectors and one scalar gives r_∞ = 148 Mflop/s and $\text{n}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 60}\text{flop}$. MIMD performance using both CPUs on one job is interpreted with the two parameters ($\text{r}{}_{\mathrm{\infty }}\text{, s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$), where $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ is the amount of arithmetic that could have been done during the time taken to synchronize the two CPUs. We find, for dyadic operations using the TSKSTART and TSKWAIT synchronization primitives, that r_∞ = 130 Mflop/s and $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 5700}\text{flop}$. This means that a job must contain more than ～ 6000 floating-point operations if it is to run at more than 50% of the maximum performance when split between both CPUs by this method. Less expensive synchronization methods using LOCKS and EVENTS reduces $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ to 4000 flop and 2000 flop respectively. A simplified form of LOCK synchronization written in CAL code further reduces $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ to 220 flop. This is probably the minimum possible value for synchronization overhead on the CRAY X-MP.     

Complex random sample scheduling and its application to an N/M/F/Fmax problem

“Complex Random Sample Scheduling(CRSS)” was proposed in this paper as an efficient heuristic method for solving any permutation scheduling problems. To show the effectiveness of the proposed CRSS, it was applied to an N-job, M-machine, permutation flowshop scheduling problem to minimize makespan, N/M/F/F_max. Numerical experiments made it clear that the proposed CRSS provides a schedule very close to the near-optimal schedule obtained by the existing promising heuristic methods such as taboo search and simulated annealing, within less computation time than these heuristic methods.     

On the M/Ck/1 queue

We obtain the exact analytic expression of the probability distribution of the number of units in a single server queue with Poisson arrivals and Coxian service time distribution (notated as M/C_k/1). A recursive procedure for calculating this probability distribution is given. The well-known queues M/E_k/1 and M/D/1 are re-derived as special cases of the M/C_k/1 queue. Finally, the cases of M/C₂/1 and M/C₃/1 are fully worked out.     

Geom/G/1/n system with LIFO discipline without interrupts and constrained total amount of customers

Consideration was given to the discrete-time queuing system with inversive servicing without interrupts, second-order geometrical arrivals, arbitrary (discrete) distribution of the customer length, and finite buffer. Each arriving customer has length and random volume. The total volume of the customers sojourning in the system is bounded by some value. Formulas of the stationary state probabilities and stationary distribution of the time of customer sojourn in the system were established.     

Properties and performance modelling of finite buffer M/G/1/K networks

Finite buffer, single-server queueing systems and networks are difficult to analyze since the length of time a customer spends in the system does not follow the Markovian property. A two-moment approximation schema is developed for the probability distribution of M/G/1/K systems and extended to the analysis of M/G/1/K   queueing networks. The general purpose of this paper is to develop a flexible and practical transform-free approach for computing the probability distribution and performance measures of the system as well as identify the underlying properties of these systems. It is shown that for most performance measures, a sigmoid or S-shaped curve with an inflection point at ρ=1$\rho =1$ appears as K→∞$K\to \infty$. This has direct implications for the analysis and optimization of such systems. The performance modelling of the M/G/1/K queueing networks of general topologies along with extensive numerical results accompany the paper along with the linear concave performance measures for these systems.     

Efficient implementation of Johnson''s rule for the n/2/F/Fmax scheduling problem

Several efficient algorithms of O(n log n) computational complexity, for the Johnson's rule to schedule a set of simultaneously available jobs on two machines in a flowship to minimize the maximum job flowtime have appeared in the literature. A modified version of one of these algorithms is presented which not only simplifies the programming effort for implementation but is also able to generate all possible optimal sequences obtainable from Johnson's rule.     

Intuitionistic fuzzy Hv-submodules

After the introduction of fuzzy sets by Zadeh, there have been a number of generalizations of this fundamental concept. The notion of intuitionistic fuzzy sets introduced by Atanassov is one among them. In this paper, we apply the concept of an intuitionistic fuzzy set to H_v-modules. The notion of an intuitionistic fuzzy H_v-submodule of an H_v-module is introduced, and some related properties are investigated. Characterizations of intuitionistic fuzzy H_v-submodules are given.