Bishop, Robert H. - The Mechatronics Handbook [CRC Press 2002] Part 4 doc

The number of equations one obtains by this technique is equal to the number of meshes in the circuit. All branch currents and voltages may subsequently be obtained from the mesh currents, as will presently be shown. Since meshes are easily identified in a circuit, this method provides a very efficient and sys- tematic procedure for the analysis of electrical circuits. The following section outlines the procedure used in applying the mesh current method to a linear circuit. Mesh Current Analysis Method 1. Define each mesh current consistently. We shall always define mesh currents clockwise, for convenience. 2. Apply KVL around each mesh, expressing each voltage in terms of one or more mesh currents. 3. Solve the resulting linear system of equations with mesh currents as the independent variables. In mesh analysis, it is important to be consistent in choosing the direction of current flow. To avoid confusion in writing the circuit equations, mesh currents will be defined exclusively clockwise when we are using this method. One-Port Networks and Equivalent Circuits This general circuit representation is shown in Fig. 11.26. This configuration is called a one-port network and is particularly useful for introducing the notion of equivalent circuits. Note that the network of Fig. 11.26 is completely described by its i-v characteristic. Thévenin and Norton Equivalent Circuits This section discusses one of the most important topics in the analysis of electrical circuits: the concept of an equivalent circuit. It will be shown that it is always possible to view even a very complicated circuit in terms of much simpler equivalent source and load circuits, and that the transformations leading to equivalent circuits are easily managed, with a little practice. In studying node voltage and mesh current analysis, you may have observed that there is a certain correspondence (called duality) between current sources and voltage sources, on the one hand, and parallel and series circuits, on the other. This duality appears again very clearly in the analysis of equivalent circuits: it will shortly be shown that equivalent circuits fall into one of two classes, involving either voltage or current sources and (respectively) either FIGURE 11.24 Basic principle of mesh analysis. FIGURE 11.25 Use of KVL in mesh analysis. FIGURE 11.26 One-port network. 0066_Frame_C11 Page 17 Wednesday, January 9, 2002 4:14 PM ©2002 CRC Press LLC The number of equations one obtains by this technique is equal to the number of meshes in the circuit. All branch currents and voltages may subsequently be obtained from the mesh currents, as will presently be shown. Since meshes are easily identified in a circuit, this method provides a very efficient and sys- tematic procedure for the analysis of electrical circuits. The following section outlines the procedure used in applying the mesh current method to a linear circuit. Mesh Current Analysis Method 1. Define each mesh current consistently. We shall always define mesh currents clockwise, for convenience. 2. Apply KVL around each mesh, expressing each voltage in terms of one or more mesh currents. 3. Solve the resulting linear system of equations with mesh currents as the independent variables. In mesh analysis, it is important to be consistent in choosing the direction of current flow. To avoid confusion in writing the circuit equations, mesh currents will be defined exclusively clockwise when we are using this method. One-Port Networks and Equivalent Circuits This general circuit representation is shown in Fig. 11.26. This configuration is called a one-port network and is particularly useful for introducing the notion of equivalent circuits. Note that the network of Fig. 11.26 is completely described by its i-v characteristic. Thévenin and Norton Equivalent Circuits This section discusses one of the most important topics in the analysis of electrical circuits: the concept of an equivalent circuit. It will be shown that it is always possible to view even a very complicated circuit in terms of much simpler equivalent source and load circuits, and that the transformations leading to equivalent circuits are easily managed, with a little practice. In studying node voltage and mesh current analysis, you may have observed that there is a certain correspondence (called duality) between current sources and voltage sources, on the one hand, and parallel and series circuits, on the other. This duality appears again very clearly in the analysis of equivalent circuits: it will shortly be shown that equivalent circuits fall into one of two classes, involving either voltage or current sources and (respectively) either FIGURE 11.24 Basic principle of mesh analysis. FIGURE 11.25 Use of KVL in mesh analysis. FIGURE 11.26 One-port network. 0066_Frame_C11 Page 17 Wednesday, January 9, 2002 4:14 PM ©2002 CRC Press LLC 12 Engineering Thermodynamics 12.1 Fundamentals Basic Concepts and Definitions • Laws of Thermodynamics 12.2 Extensive Property Balances Mass Balance • Energy Balance • Entropy Balance • Control Volumes at Steady State • Exergy Balance 12.3 Property Relations and Data 12.4 Vapor and Gas Power Cycles Although various aspects of what is now known as thermodynamics have been of interest since antiquity, formal study began only in the early nineteenth century through consideration of the motive power of heat: the capacity of hot bodies to produce work. Today the scope is larger, dealing generally with energy and entropy, and with relationships among the properties of matter. Moreover, in the past 25 years engineering thermodynamics has undergone a revolution, both in terms of the presentation of funda- mentals and in the manner that it is applied. In particular, the second law of thermodynamics has emerged as an effective tool for engineering analysis and design. 12.1 Fundamentals Classical thermodynamics is concerned primarily with the macrostructure of matter. It addresses the gross characteristics of large aggregations of molecules and not the behavior of individual molecules. The microstructure of matter is studied in kinetic theory and statistical mechanics (including quantum thermodynamics). In this chapter, the classical approach to thermodynamics is featured. Basic Concepts and Definitions Thermodynamics is both a branch of physics and an engineering science. The scientist is normally interested in gaining a fundamental understanding of the physical and chemical behavior of fixed, quiescent quantities of matter and uses the principles of thermodynamics to relate the properties of matter. Engineers are generally interested in studying systems and how they interact with their surround- ings. To facilitate this, engineers have extended the subject of thermodynamics to the study of systems through which matter flows. System In a thermodynamic analysis, the system is the subject of the investigation. Normally the system is a specified quantity of matter and/or a region that can be separated from everything else by a well-defined surface. The defining surface is known as the control surface or system boundary . The control surface may be movable or fixed. Everything external to the system is the surroundings . A system of fixed mass is Michael J. Moran The Ohio State University ©2002 CRC Press LLC 13 Modeling and Simulation for MEMS 13.1 Introduction 13.2 The Digital Circuit Development Process: Modeling and Simulating Systems with Micro- (or Nano-) Scale Feature Sizes 13.3 Analog and Mixed-Signal Circuit Development: Modeling and Simulating Systems with Micro- (or Nano-) Scale Feature Sizes and Mixed Digital (Discrete) and Analog (Continuous) Input, Output, and Signals 13.4 Basic Techniques and Available Tools for MEMS Modeling and Simulation Basic Modeling and Simulation Techniques • A Catalog of Resources for MEMS Modeling and Simulation 13.5 Modeling and Simulating MEMS, i.e., Systems with Micro- (or Nano-) Scale Feature Sizes, Mixed Digital (Discrete) and Analog (Continuous) Input, Output, and Signals, Two- and Three-Dimensional Phenomena, and Inclusion and Interaction of Multiple Domains and Technologies 13.6 A “Recipe” for Successful MEMS Simulation 13.7 Conclusion: Continuing Progress in MEMS Modeling and Simulation 13.1 Introduction Accurate modeling and efficient simulation, in support of greatly reduced development cycle time and cost, are well established techniques in the miniaturized world of integrated circuits (ICs). Simulation accuracies of 5% or less for parameters of interest are achieved fairly regularly [1], although even much less accurate simulations (25–30%, e.g.) can still be used to obtain valuable information [2]. In the IC world, simulation can be used to predict the performance of a design, to analyze an already existing component, or to support automated synthesis of a design. Eventually, MEMS simulation environments should also be capable of these three modes of operation. The MEMS developer is, of course, most interested in quick access to particular techniques and tools to support the system currently under development. In the long run, however, consistently achieving acceptably accurate MEMS simulations will depend both on the ability of the CAD (computer-aided design) community to develop robust, efficient, user-friendly tools which will be widely available both to cutting-edge researchers and to production engineers and on the existence of readily accessible standardized processes. In this chapter we focus on fundamental approaches which will eventually lead to successful MEMS simulations becoming routine. Carla Purdy University of Cincinnati ©2002 CRC Press LLC . engineers have extended the subject of thermodynamics to the study of systems through which matter flows. System In a thermodynamic analysis, the system is the subject of the investigation kinetic theory and statistical mechanics (including quantum thermodynamics). In this chapter, the classical approach to thermodynamics is featured. Basic Concepts and Definitions Thermodynamics. uses the principles of thermodynamics to relate the properties of matter. Engineers are generally interested in studying systems and how they interact with their surround- ings. To facilitate this,