OPAC - Pencarian Artikel Jurnal & Majalah Library USD
Menampilkan semua artikel (Halaman 687 dari 34166, Total: 341652 data)
Trends in low-power RAM circuit technologies
klik untuk membaca file PDF
| Pengarang | : | K. Itoh |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-4, APRIL (No. 4) |
| Halaman | : | 524-543 |
| Abstrak | : | Trends in low-power circuit technologies of CMOS RAM chips are reviewed in terms of three key issues: charging capacitance, operating voltage, and dc current. The discussion includes a general description of power sources in a RAM chip, and covers both DRAMs and SRAMs. In DRAMs, successive circuit advancements have produced a power reduction equivalent to two to three orders of magnitude over the last decade for a fixed memory capacity chip. Coupled with the low-power advantage of CMOS circuits, two technologies have been the major contributors to power reduction: lower charging capacitance due to partial activation of multi-divided arrays that use multi-divisions of data and word lines; and lower operating voltage resulting from external power supply reduction, half-V/sub DD/ precharging and on-chip voltage down converting scheme. In SRAMs, partial activation of a multi-divided word line drastically reduces the dc current from the data-line load to the selected cell. In addition to advances in the sense amplifier circuit, an auto power down scheme that uses address transition detection for word driver and column circuitry further reduces the dc current. It is also shown that to design ultralow voltage DRAMs and SRAMs, the application of subthreshold current reduction circuits (such as source-gate back biasing) to cell and iterative circuit blocks will be indispensable in the future. |
Minimizing power consumption in digital CMOS circuits
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-4, APRIL (No. 4) |
| Halaman | : | 498-523 |
| Abstrak | : | An approach is presented for minimizing power consumption for digital systems implemented in CMOS which involves optimization at all levels of the design. This optimization includes the technology used to implement the digital circuits, the circuit style and topology, the architecture for implementing the circuits and at the highest level the algorithms that are being implemented. The most important technology consideration is the threshold voltage and its control which allows the reduction of supply voltage without significant impact on logic speed. Even further supply reductions can be made by the use of an architecture-based voltage scaling strategy, which uses parallelism and pipelining, to tradeoff silicon area and power reduction. Since energy is only consumed when capacitance is being switched power can be reduced by minimizing this capacitance through operation reduction choice of number representation, exploitation of signal correlations, resynchronization to minimize glitching, logic design, circuit design, and physical design. The low-power techniques that are presented have been applied to the design of a chipset for a portable multimedia terminal that supports pen input, speech I/O and full-motion video. The entire chipset that performs protocol conversion, synchronization, error correction, packetization, buffering, video decompression and D/A conversion operates from a 1.1 V supply and consumes less than 5 mW. |
Expert supervision of fuzzy learning systems for fault tolerant aircraft control
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 466-483 |
| Abstrak | : | In this paper, we begin by showing that the fuzzy model reference learning controller (FMRLC) can be used to reconfigure the nominal controller in an F-16 aircraft to compensate for various actuator failures without using explicit failure information. Next, we show that the performance of the FMRLC can be significantly enhanced by exploiting failure detection and identification (FDI) information to achieve a "performance adaptive" system that seeks an appropriate performance level depending on the type of failure that occurred. We develop an expert supervision strategy for the FMRLC that uses only information about the time at which a failure occurs and show that it achieves higher performance control reconfiguration than an unsupervised FMRLC. In addition we show that similar performance can be achieved if we only use estimates of the failure time and magnitude obtained from a fuzzy estimator. We close our study with a brief assessment of the advantages and disadvantages of the approaches used in this paper. |
Industrial applications of fuzzy logic at General Electric
| Pengarang | : | P.P. Bonissone |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 450-465 |
| Abstrak | : | Fuzzy logic control (FLC) technology has drastically reduced the development time and deployment cost for the synthesis of nonlinear controllers for dynamic systems. As a result we have experienced an increased number of FLC applications. We illustrate some of our efforts in FLC technology transfer, covering projects in turboshaft aircraft engine control, steam turbine startup, steam turbine cycling optimization, resonant converter power supply control, and data-induced modeling of the nonlinear relationship between process variables in a rolling mill stand. We compare these applications in a cost/complexity framework, and examine the driving factors that led to the use of FLCs in each application. We emphasize the role of fuzzy logic in developing supervisory controllers and in maintaining explicit tradeoff criteria used to manage multiple control strategies. Finally, we describe some of our FLC technology research efforts in automatic rule base tuning and generation, leading to a suite of programs for reinforcement learning, supervised learning, genetic algorithms, steepest descent algorithms, and rule clustering. |
Application of fuzzy logic to reliability engineering
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 435-449 |
| Abstrak | : | The analysis of system reliability often requires the use of subjective-judgments, uncertain data, and approximate system models. By allowing imprecision and approximate analysis fuzzy logic provides an effective tool for characterizing system reliability in these circumstances; it does not force precision where it is not possible. Here we apply the main concepts of fuzzy logic, fuzzy arithmetic and linguistic variables to the analysis of system structures, fault trees, event trees, the reliability of degradable systems, and the assessment of system criticality based on the severity of a failure and its probability of occurrence. |
Hardware solutions for fuzzy control
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 422-434 |
| Abstrak | : | A large fraction of software designs using microcontrollers is today adopting fuzzy logic algorithms and this fraction is likely to increase in the future. Hardware implementation of fuzzy logic ranges from standard microprocessors to dedicated ASICs and each different approach is targeted to a different application domain or market area. In this paper, we present an overview of the computational complexity of the fuzzy inference process and the various techniques adopted for fuzzy control tasks, highlighting the tradeoffs that can guide a system designer toward correct choices according to application features and cost/performance issues. In addition, we detail three case studies of architectures that address three different market segments in the fuzzy hardware scenario: dedicated fuzzy coprocessors, RISC processors with specialized fuzzy support and application specific fuzzy ASICs. |
Fuzzy logic control-a taxonomy of demonstrated benefits
| Pengarang | : | D.E. Thomas |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 407-421 |
| Abstrak | : | The motivations for fuzzy logic control (FLC) are illuminated by exploring the benefits obtained by application designers through its use. A context for this exploration is set with a discussion of the characteristics of control policies and of the general attributes of FLC. Each benefit is described by reference to reported FLC implementations in which the benefit is demonstrated. Based on common features of the example applications, application preconditions for obtaining each benefit are stated. |
Neuro-fuzzy modeling and control
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 378-406 |
| Abstrak | : | Fundamental and advanced developments in neuro-fuzzy synergisms for modeling and control are reviewed. The essential part of neuro-fuzzy synergisms comes from a common framework called adaptive networks, which unifies both neural networks and fuzzy models. The fuzzy models under the framework of adaptive networks is called adaptive-network-based fuzzy inference system (ANFIS), which possess certain advantages over neural networks. We introduce the design methods for ANFIS in both modeling and control applications. Current problems and future directions for neuro-fuzzy approaches are also addressed. |
Fuzzy logic systems for engineering: a tutorial
| Pengarang | : | J.M. Mendel |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-3, MARCH (No. 3) |
| Halaman | : | 345-377 |
| Abstrak | : | A fuzzy logic system (FLS) is unique in that it is able to simultaneously handle numerical data and linguistic knowledge. It is a nonlinear mapping of an input data (feature) vector into a scalar output, i.e., it maps numbers into numbers. Fuzzy set theory and fuzzy logic establish the specifics of the nonlinear mapping. This tutorial paper provides a guided tour through those aspects of fuzzy sets and fuzzy logic that are necessary to synthesize an FLS. It does this by starting with crisp set theory and dual logic and demonstrating how both can be extended to their fuzzy counterparts. Because engineering systems are, for the most part, causal, we impose causality as a constraint on the development of the FLS. After synthesizing a FLS, we demonstrate that it can be expressed mathematically as a linear combination of fuzzy basis functions, and is a nonlinear universal function approximator, a property that it shares with feedforward neural networks. The fuzzy basis function expansion is very powerful because its basis functions can be derived from either numerical data or linguistic knowledge, both of which can be cast into the forms of IF-THEN rules. |
The Blasius Function: Computations Before Computers, the Value of Tricks, Undergraduate Projects, and Open Research Problems
| Pengarang | : | John P. Boyd |
| Nama Majalah/Jurnal | : | Siam Review |
| Volume / Edisi | : | 50-4, DECEMBER (No. 4) |
| Halaman | : | 791-804 |
| Abstrak | : | The Blasius flow is the idealized flow of a viscous fluid past an infinitesimally thick, semi-infinite flat plate. The Blasius function is the solution to on subject to . We use this famous problem to illustrate several themes. First, although the flow solves a nonlinear partial differential equation (PDE), Toepfer successfully computed highly accurate numerical solutions in 1912. His secret was to combine a Runge–Kutta method for integrating an ordinary differential equation (ODE) initial value problem with some symmetry principles and similarity reductions, which collapse the PDE system to the ODE shown above. This shows that PDE numerical studies were possible even in the precomputer age. The truth, both a hundred years ago and now, is that mathematical theorems and insights are an arithmurgist's best friend, and they can vastly reduce the computational burden. Second, we show that special tricks, applicable only to a given problem, can be as useful as the broad, general methods that are the fabric of most applied mathematics courses: the importance of “particularity.” In spite of these triumphs, many properties of the Blasius function are unknown. We give a list of interesting projects for undergraduates and another list of challenging issues for the research mathematician. |