Cycle times in single server cyclic Jackson networks

Using the arrival theorem together with elementary facts regarding integrated tail distributions and length-biased sampling we obtain closed form expressions for the inter-output time and the cycle time distribution in cyclic, single-class Jackson networks. Corresponding expressions for the normalization constant and the throughput are also obtained.     

13C-NMR-Untersuchungen von Substituenteneffekten in mehrfach substituierten Benzen-und Naphthalenverbindungen: Inkrementberechnungen der13C-chemischen Verschiebungen

Summary The aryl¹³C chemical shifts of Cl-substituted 4-amino-, 4-diazonium-N,N-dimethylanilines, N,N-dimethylanilines and differently substituted naphthalenes were assigned by means of different NMR methods. The assignments were compared with chemical shifts obtained by using empirical additivity relationship for mono substituted aromatic substances. As a means of substitutent interactions, the chemical shift difference between calculated and experimental values ( _c ⁱ ) has been used. In the presence of remarkable steric and electronic substituent interactions, large deviations from additivity ( _c ⁱ values up to 15.4 ppm) were found. Which originate primarily from steric interactions between the substitutents. In order to account therefore, correction increments have been developed by employing the _c ⁱ values obtained from 1,2-disubstituted benzenes or naphthalenes. The¹³C chemical shifts of more than seventy substituted benzenes and naphthalenes have been predicted. The results corroborate that reasonable calculation of chemical shifts in sterically hindered benzenes is possible by using the extended additivity rule. The _c ⁱ values are much lower and allow reasonable structural assignments.For external users of this incremental system, a computer program for IBM compatible PC/AT was developed. By means of this program, the¹³C chemical shifts for different benzenes and naphthalenes with or without 1,2-disubstituted correction increments will be calculated and the corresponding spectrum displayed. The program can assist the successful assignment of experimental¹³C chemical shifts.

     

Prediction of retention data when using incremental multiple development techniques

Summary The apparentRF value of a compound after successive development steps in incremental multiple development (IMD) is determined. The model developed enables prediction of the migration and the zone width of investigated compounds in IMD with linearly and quadratically increasing development distances. For the experimental investigations we examined naturally occurring compounds as model substances on different stationary phases. The coincidence of predicted and measured chromatographic data strongly support our formulas. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

基于飞行器网络控制系统的多速率控制器设计

为了减少网络环境中的时延和数据包丢失对飞行器网络控制器系统的影响,设计了一种具有多速率的保性能控制器设计方法;多速率是指在具有多通道数据传输的系统中,各通道所需控制输入的频率不完全相同;在存在时延和丢包的情况下,利用增广技术对飞行器控制系统在整个循环周期内建立离散模型,此时为了使多速率控制方法更加有效,先基于此模型在控制器输入端构造一个预测器,根据预测器的输出为整个系统设计一个具有多控制速率的动态输出反馈控制器;然后给出并证明保性能控制器的存在条件和求解方法;最后通过某飞行器网络控制系统的数值算例验证了所提方法的有效性。     

基于STM32的温湿度变送器设计

针对目前常见的电流型温湿度变送器恒流输出特性较差、精度较低、校准繁琐的不足,给出了一种基于STM32单片机的温湿度变送器设计方案。该电路以STM32单片机为控制核心,以SHT11数字式温湿度传感器采集环境温湿度。通过STM32的内部12位D/A输出模块将温湿度转换为模拟电压信号。随后,该电压信号通过V/I转换电路变为4～20mA的模拟电流信号。研究了常见V/I转换电路的原理并提出改进电路方案。最后,基于STM32的内部FLASH存储功能给出了一种上位机软件校准方案。通过对比仿真和实验表明,该变送器具有成本较低、恒流特性较好、精度较高、校准快捷方便的优点,能够满足工农业生产中常规温湿度测量的要求。     

An incremental attribute reduction approach based on knowledge granularity under the attribute generalization

Attribute reduction is a key step to discover interesting patterns in the decision system with numbers of attributes available. In recent years, with the fast development of data processing tools, the information system may increase quickly in attributes over time. How to update attribute reducts efficiently under the attribute generalization becomes an important task in knowledge discovery related tasks since the result of attribute reduction may alter with the increase of attributes. This paper aims for investigation of incremental attribute reduction algorithm based on knowledge granularity in the decision system under the variation of attributes. Incremental mechanisms to calculate the new knowledge granularity are first introduced. Then, the corresponding incremental algorithms are presented for attribute reduction based on the calculated knowledge granularity when multiple attributes are added to the decision system. Finally, experiments performed on UCI data sets and the complexity analysis show that the proposed incremental methods are effective and efficient to update attribute reducts with the increase of attributes.     

Output tracking of switched Boolean networks under open-loop/closed-loop switching signals

This paper addresses the output tracking problem of switched Boolean networks (SBNs) via the semi-tensor product method, and presents a number of new results. Firstly, the concept of switching-output-reachability is proposed for SBNs, based on which, a necessary and sufficient condition is presented for the output tracking of SBNs under arbitrary open-loop switching signal. Secondly, a constructive procedure is proposed for the design of closed-loop switching signals for SBNs to track a constant reference signal. The study of an illustrative example shows that the obtained new results are very effective.     

信号调制三值噪声作用下有源低通滤波器中的随机共振

研究了具有信号调制三值噪声的低通滤波器电路中的随机共振现象.基于线性系统理论,利用三值噪声的统计性质,得到了低通滤波器的输出幅度增益的解析表达式.研究表明,输出幅度增益随激励周期信号的频率、低通滤波器电路的电容量、电阻值、噪声的幅度及平坦度的非单调函数.系统截止频率和带宽比没有噪声时明显增大.     

Electrospun PVDF/Cloisite-30B and PVDF/BaTio3/graphene nanofiber mats for development of nanogenerators

The research work mainly focusses on the preparation of nanogenerators based on PVDF/Cloisite-30B and PVDF/BaTiO₃/Graphene polymer nano composites using electrospinning technique. The process parameters were designed and optimized by applying Taguchi's Design of Experiments with L₄ array. Morphology of the polymer composites were studied using Scanning Electron Microscopic images. β-phase Crystallinity of PVDF/Cloisite-30B and PVDF/BaTiO₃/Graphene was 85% and 80% respectively when it is estimated using FTIIR spectroscopic technique. The nanogenerator with PVDF/BaTiO₃/Graphene produced 3.65 V and the same was 3.5 V in case of PVDF/Cloisite-30B nano composites. Better crystallinity was observed in PVDF/Cloisite-30B fiber mats but improved sensitivity of PVDF/BaTiO₃/Graphene resulted in slight enhancement of output voltage. The result indicates the ability of polymer composites as nanogenerator for development of wearable self-powered electronic devices for smart sensing applications.