On the realization of gyrators by nullors and resistors

It is proved that for the realization of a gyrator by nullors and resistors, at least two nullors and at least two resistors are needed. A generalization is the result that any n-port network possessing both an impedance and an admittance matrix and consisting of nullors and resistors must contain at least n resistors. It is conjectured that a realization of a gyrator with only two nullors requires four resistors and a realization of a gyrator with only two resistors requires three nullors.     

On the minimal realization of the gyrator by means of nullors and resistors

This paper is a second step in the proof of the conjecture that it is impossible to synthesize a gyrator by means of nullors and linear resistors with fewer than four resistors if only two nullors are permitted, or with fewer than three nullors if only two resistors are permitted. It is proved that a gyrator cannot be realized with only two nullors and two resistors. In a forthcoming paper (third step) it will be proved that a two-nullor, three-resistor gyrator realization cannot be obtained. The proofs are presented in such a way that at the same time a synthesis procedure for minimal nullor-resistor networks is demonstrated.     

On the minimal realization of the gyrator by means of nullors and resistors. II

It is proved that it is impossible to synthesize a gyrator with only two nullors and three resistors. Combining the results obtained in References 1 and 2 and in this paper, we obtain the following necessary and sufficient conditions: a nullor-resistor gyrator realization is minimal if and only if it consists of either two nullors and four resistors or three nullors and two resistors.     

Using nullors to analyse linear networks

Analysis of linear networks using nullors is considered. A simplified procedure is presented for doing nodal analysis of RLC nullor networks by computer. It is shown that using nullors to analyse linear networks is equivalent to doing modified nodal analysis.     

Loop equation formulation for switched capacitor networks containing nullors

A method is given for determining the loop equations of an ideal active switched capacitance (SC) network containing switches, capacitors and nullors. These equations are obtained directly by row-column operations on the passive unswitched loop elastance matrix. the results are extended for the P- phase case. It is shown that the loop charges can be solved for and that the branch voltages can be obtained from the loop charges.     

Design of the CMOS inverter-based amplifier: A quantitative approach

The CMOS inverter can be used as an amplifier if properly biased in the transition region of its voltage-transfer characteristics (VTC). In this paper, the design of this amplifier is investigated with its merits and demerits illustrated and with the various trade-offs involved in its design discussed. Specifically, the following performance metrics are discussed quantitatively: gain, area, linearity, maximum allowable swing, bandwidth, stability, noise factor, impedance matching, and slew rate. Also, the effect of process, voltage, and temperature (PVT) variations are investigated. The optimum number of stages corresponding to the minimum area required for achieving a certain voltage gain is determined. The results obtained from the quantitative analysis and the simulation are discussed.     

The realization of inverse system for circuits containing nullors with applications in chaos synchronization

A very simple method for synthesizing the inverse system of a non-linear non-autonomous circuit containing nullors is proposed. The main application of the procedure is the synchronization of chaos by the inverse system approach. This is illustrated with two examples: the synchronization of a Duffing circuit and a communication scheme by direct chaotic modulation using Chua's circuit. © 1998 John Wiley & Sons, Ltd.     

Efficient generation of compact symbolic network functions in a nested rational form

This paper presents the extension of generalized parameter extraction method for direct circuit function generation in a fully symbolic form of rational expressions or a nested s-expanded polynomial. The new formula for implicit extraction of parameters that allows effective factoring by grouping of determinants of circuits containing any linear models of active elements, such as controlled sources, nullors, and pathological mirrors, is proposed. The concept of nullor with parameter is used for implicit extraction. The rules of optimal selection of parameters for extraction are presented. The proposed algorithm of symbolic analysis is implemented in the CirSym program, which is available online. The paper discusses the results of automatic analysis of several large active circuits, as well as determinants of matrixes and passive topologies, in terms of compact size and minimization of the number of arithmetic operations. Experimental results demonstrate that the expressions of determinants derived by CirSym are more compact than the results of the factorization algorithms of commercial computer algebra systems. The comparison with several other symbolic analysis algorithms shows that CirSym is the only available program that provides the exact calculation of the symbolic function of large circuits in the s-expanded form with every coefficient being a compact-nested expression.     

Extension of the normal tree method

The results of this paper are applicable to linear electrical networks that may contain ideal transformers, nullors, independent and controlled sources, resistors, inductors, and capacitors, and, under a topological restriction, gyrators. A relation between summands of some expansion of the network determinant and pairs of conjugate trees is proved, which uncovers the equivalence of known criteria on generic solvability based on matroids and those based on pairs of conjugate trees. New criteria on the solvability of active networks are given. A method to obtain complete sets of generic state co‐ordinates is established, which includes the following extension of the wellknown normal tree method: The generic order of complexity equals the sum of the number of forest capacitors and the number of co–forest inductors in any normal pair of conjugate trees, the latter term being introduced in this paper. The voltages across the forest capacitors together with the currents through the co‐forest inductors may be given initial values independently from each other. Further, a systematic method of augmentation that yields networks of generic index 1 is proposed. All results are expressed in terms of network determinants as well as in terms of network graphs, and all given criteria may be checked by efficient algorithms. Copyright © 1999 John Wiley & Sons, Ltd.     

Revisited generalized substitution theorem and its consequences for circuit analysis

The Substitution Theorem (ST) is generally perceived as a mere theoretical curiosity. In this paper, a formerly derived generalized ST (GST) is carefully revised, which leads to both a Weak Revisited GST (RGST) and a Strong RGST (characterized by noticeably relaxed hypotheses with respect to the GST). Then, despite the common opinion about the ST, such RGSTs are showed to be powerful analytical tools to generalize, make rigorous and rigorously prove several classic results of Circuit Theory, namely: the Substitution Theorem for Multiterminal Circuits, the Source‐Shift Theorem, the Thévenin–Norton Theorem, the Miller Theorem alongside its Dual, and the Augmentation Principle. More specifically, the Substitution Theorem for Multiterminal Circuits is extended to an arbitrary set of sources, possibly including nullors. The Source‐Shift Theorem is rigorously derived, and possible related ambiguities are removed. Also, all possible hybrid forms of the Thévenin–Norton Theorem for multiports are individuated, and a precise operative procedure for calculating the relevant entities is provided for all cases. Furthermore, the Miller Theorem and its Dual are extended to an arbitrary number of variables and to multiports. As to the Augmentation Principle, the constraint regarding the linearity of the augmenting resistors is removed. Finally, thoroughly worked examples are given in which the aforementioned noteworthy consequences of the RGSTs are proved to be efficient tools for analysis by inspection of linear and nonlinear circuits. Among the other things, systematic pencil‐and‐paper procedures for DC‐point and input‐output (or driving‐point) characteristic calculation in nonlinear networks are derived and applied to circuits with considerably complex topology. Copyright © 2016 John Wiley & Sons, Ltd.     

SRAM circuit-failure modeling and reliability simulation with SPICE

Based on some new accelerated lifetime models and failure equivalent circuit modeling techniques for the common semiconductor wear out mechanisms, simulation program with integrated circuit emphasis (SPICE) can be used to characterize CMOS VLSI circuit failure behaviors and perform reliability simulation. This paper used a simple SRAM circuit as an example to demonstrate how to apply SPICE to circuit reliability modeling, simulation, analysis, and design. The SRAM circuit, implemented with a commercial 0.25-/spl mu/m technology, consists of functional blocks of 1-bit six-transistor cell, precharge, read/write control, and sense amplifier. The SRAM operation sequence of "write 0, read 0, write 1, read 1" was first simulated in SPICE to obtain the terminal voltage and current stress profiles of each transistor. Then, normalized lifetimes of all transistors in terms of each failure mechanism were calculated with the corresponding accelerated lifetime models. These lifetime values were sorted to single out the most damaged transistors. Finally, the selected transistors were substituted with failure equivalent circuit models, and SPICE simulations were performed again to characterize the circuit performance, functionality, and failure behaviors. The simulation shows that the 0.25-/spl mu/m technology, hot-carrier injection (HCI), and time-dependent dielectric breakdown (TDDB) had significant effects on SRAM-cell stability and voltage-transfer characteristics, while negative bias temperature instability (NBTI) mainly degraded the cell transition speed when the cell state flipped. This illustrative SRAM simulation work proves that, with SPICE and the failure equivalent circuit models, circuit designers can better understand the damage effects of HCI/TDDB/NBTI on the circuit operation, quickly estimate the circuit lifetime, make appropriate performance/reliability tradeoffs, and formulate practical design guidelines to improve the circuit reliability.     

三维CAD系统及其在产品设计开发中的应用

本文以三维辅助设计软件Ｐｒｏ／ＥＮＧＩＮＥＥＲ设计开发接触器为例。介绍三维计算机系统的功能与特点、组成、硬件要求以及在产品设计开发中的应用。     

弱电磁环网运行控制若干问题及对策

电磁环网是电网发展的阶段性产物,在一定时期不可避免。当电网中出现弱电磁环网时,系统运行将面临较大的安全风险。文中对弱电磁环网运行控制面临的问题和对策进行了研究。提出了弱电磁环网的3个主要特征,指出了弱电磁环网运行控制面临的4类主要问题;分别对这4类问题进行研究,提出了相应的控制对策,并结合实际系统算例进行分析。算例分析结果表明了所述控制策略的有效性,对弱电磁环网运行控制具有参考意义。     

Less-flammable liquids used in transformers

Two main types of replacement liquid have been developed, high molecular-weight hydrocarbons and polydimethylsiloxane (silicone). These liquids are formulated to withstand fairly large amounts of electrical arcing, and are less flammable than mineral oils. These properties qualify the liquids for use in installations where less-flammable liquids are required and where the use restrictions associated with the products are followed. The requirements of the National Electrical Code are described and the advantages of using less-flammable liquids are also described. The fault mechanisms of transformers are discussed. The UL investigation of transformer liquids and the limitations of use are also discussed     

Prospects for using the technology of circulating fluidized bed for technically refitting Russian thermal power stations

The present state and development of circulating fluidized bed (CFB) technology around the world are briefly reviewed. Questions of increasing the capacity of single boiler units and raising the parameters of steam are discussed. CFB boilers for 225- and 330-MW power units are described and their parameters are estimated as applied to the conditions of firing different Russian fuels. Indicators characterizing CFB boilers and pulverized-coal boilers are given. Capital outlays and operational costs for new coal-fired units are compared, and the results from this comparison are used to show the field of the most promising use of the CFB technology during technical refitting of Russian thermal power stations.     

电力系统电压稳定性及负荷对其影响研究现状

综述了电力系统电压稳定性及负荷对其影响的研究现状.介绍了国内外较有代表性的几种电压稳定性定义,分析了短期电压失稳和长期电压失稳的机理,论述了电压稳定性主要分析方法的原理,总结了各种电压稳定性指标的特点.重点阐述了负荷的恢复特性和失稳特性对系统电压失稳的影响,并指出负荷对电压稳定性影响方面研究的主要内容:负荷在其端电压下降时的响应特性,建立适合于电压稳定分析的负荷模型,负荷区域的电压稳定控制措施.     

Magnet wire enamels-which one?

The factors involved in the selection of a magnet wire enamel are explored. Three categories of application are discussed: motors, transformers and open coils, and encapsulated coils. Magnet wire tests are reviewed. The influence of manufacturer requirements on wire selection and the requirements for runnability of magnet wire are examined. Enamel types and their properties are tabulated. Applications of the various types are indicated     

GPRS负荷管理系统运行问题的分析及解决措施

针对保定供电公司GPRS负荷管理系统运行过程中系统运行速度慢的问题进行了测试、分析,并提出具体的改进措施,如对统计功能和补测功能SQL语句进行优化、系统硬件配置的升级等,确保了系统的正常运行。     

具有良好维护性和通用性的电网操作票专家系统

针对目前电网操作票专家系统所存在的问题,提出了解决传统的电网操作票专家系统在可维护性和通用性方面的问题应采取的途径。其重点在于对知识的认知过程及表达方式。应将知识规则存在数据库中,并可进行方便的补充和修改但却无须修改程序代码。推理过程模仿现场专家将一次和二次系统操作分开进行,操作代码最后通过术语词典翻译成操作指令解决各地指令不同问题。并介绍了具有良好维护性和通用性的电网操作票专家系统的功能。