Time-weighted quadratic performance indices for linear systems

Some analytical results are derived and established for the time-weighted quadratic Performance Indices (PF's) of a linear, time-invariant system in this letter. The final cost as well as the recursive formulas are developed and established in concise forms.     

Minimal indices in dynamical systems

Minimal indices are important for the understanding of dynamical systems, and this letter reports some of their properties.     

Topological considerations for autoregressive systems with fixed Kronecker indices

In this paper we will study topological properties of the class of proper and improperp×m transfer functions of a fixed McMillan degreen. A natural generalization of this class is all autoregressive systems of degreen under external system equivalence. The subset of irreducible systems has in a natural way the structure of a manifold and we show how to extend this topology to the set of all autoregressive systems of degree at mostn. We will describe the subset of systems with fixed Kronecker indicesv=(v₁,...,v _p ) as an orbit space, which will enable us to calculate the topological dimension for each collection of indicesv. Finally, we will describe the topological closure of those sets in the space of all autoregressive systems.Supported in part by NSF grant DMS-9201263Supported in part by Frank M. Freimann chair in Electrical Engineering.Supported in part by the Research Enhancement Fund from College of Art and Sciences, Texas Tech University.     

Optimization of planar reflector systems for a set of quality indices

Characteristics of a planar double-reflector aplanatic Schwarzschild system that allow estimation of the efficiency of its application in devices of integrated microwave optics are analyzed. The results of multicriteria optimization of the system’s quality indices are obtained. The aplanatic system is compared to systems with parabolic reflectors: a single-reflector system and a double-reflector system with flat subreflector. It is shown that the results of optimization obtained in the approximation of physical optics agree well with the results of the analysis and minimization of aberrations in the reflector system performed with the use of the proposed criterion of rms aberrations. Scanning characteristics of Pareto-optimal planar aplanats are presented.     

Evaluation of error probability for partial response systems

A computation algorithm has been developed to evaluate the exact probability of error for partial response (p.r.) signals in the presence of intersymbol interference and additive Gaussian noise in a digital communication system for a wide range of signal/noise ratio and sampling time error. This can readily be used to study the performance of already familiar p.r. signals or any new p.r. format which can be composed from a general p.r. polynomial.     

电子不停车收费系统性能的一种评价方法

针对各省市ETC交易耗时不同,且缺少对ETC系统整体或主要组成部分的性能表现评价的有效方法,采用随机过程与数理统计的方法,提出对交易耗时进行数字特征分析和参数估计的评价方法。通过某省高速公路二百多万条ETC成功交易数据实例分析证明,该评价方法可从横向、纵向及不同环境条件等多角度有效地综合评价ETC系统的性能表现情况,为ETC系统的设计、选型、建设、运营等多方面提供参考。     

Evaluation of header compression schemes for IP-based wireless access systems

For mobile IP-based telephony (voice over IP) and IP-based real-time multimedia over cellular radio systems, an economically viable solution is needed. It is an absolute requirement that, for example, the 60-octet IPv6/UPD/RTP headers on IP telephony packets be reduced in size to conserve bandwidth in the radio spectrum. We evaluate the performance of two header compression schemes, based on RFCs 2508 and 3095, under the conditions of cellular radio access technology. The results presented in this article refer to voice and Web browsing traffic and are based on the implementation of compression/decompression algorithms for the aforementioned standards. We find that RFC 3095 performs significantly better if used for mobile communications.     

Reliability indices for electric-power wheeling

Transmission networks are being used more extensively to accommodate energy transactions that use the economic benefits of pooling. This paper evaluates the probabilistic wheeling capability of an interconnected power transmission system. Large electric power wheeling can degrade the reliability of the electric power network. This problem is also important for power system control and planning purposes. This paper discusses, from the viewpoint of power network reliability, the problem of power wheeling from Western Europe to Greece through the Yugoslav electric power system. The relative cost of the wheeling due to reliability indices is 2% of the production cost for the power wheeled. The calculation of reliability indices of wheeling enable more adequate estimation of the wheeling rate for power transactions between utilities. This paper describes an approach to calculate cost of the average energy not supplied and load curtailed due to wheeling. This cost can even be negative, which depends mostly on the amount of wheeling power and consumer loads. The reliability index EENS (expected energy not supplied) is more comprehensive than PI (performance index) for the contingency severity selection procedure     

Evaluation of automated biometrics-based identification andverification systems

Recent advancements in computer technology have increased the use of automated biometric-based identification and verification systems. These systems are designed to detect the identity of an individual when it is unknown or to verify the individual's identity when it is provided. These systems typically contain a series of complex technologies that work together to provide the desired results in turn, evaluating these systems is also a complex process. The authors provide a method that may be used to evaluate the performance of automated biometric-based systems. The method is derived from fundamental statistics and is applicable to a variety of systems. Examples are provided to demonstrate the practicality of the method     

New reliability indices for topological design

Starting from the establishment of the correlation between computer communication network reliability and the topological parameters of its associated graph, an original heuristic method is proposed in order to optimize the networks by using new topological indices of reliability.     

Evaluation of direct attacks to fingerprint verification systems

The vulnerabilities of fingerprint-based recognition systems to direct attacks with and without the cooperation of the user are studied. Two different systems, one minutiae-based and one ridge feature-based, are evaluated on a database of real and fake fingerprints. Based on the fingerprint images quality and on the results achieved on different operational scenarios, we obtain a number of statistically significant observations regarding the robustness of the systems.     

Evaluation of modal noise in multimode fiber-optic systems

Modal noise at fiber connecting points is studied theoretically and experimentally. Simple formulas for calculating modal-noise power, noise bandwidth, and nonlinear distortions are obtained by introducing a visibility concept. Modal noise for multimode operating LD is also analyzed. These theoretical results are applied to high-bit-rate digital systems and analog systems using direct IM. Then, it is shown that a 3-dB connection loss limits effective signal-to-noise ratio (SNR) to 22 dB in high-bit-rate digital systems, and that in analog systems, the SNR is improved more than 20 dB by using a superimposed pulse modulation with a frequency that is 100 times the baseband signal bandwidth.     

Evaluation of transitive closure in distributed database systems

A special schema is constructed to represent the data of a binary relation so that the transitive closure can be evaluated efficiently in distributed database systems. The method is economical in communication cost and at the same time preserves the fast access paths for efficient parallel processing of transitive closure at local sites. Updating of data is also discussed     

Refractive indices of liquid crystals for display applications

This paper reviews the extended Cauchy model and the four-parameter model for describing the wavelength and temperature effects of liquid crystal (LC) refractive indices. The refractive indices of nine commercial LCs, MLC-9200-000, MLC-9200-100, MLC-6608, MLC-6241-000, 5PCH, 5CB, TL-216, E7, and E44 are measured by the Multi-wavelength Abbe Refractometer. These experimental data are used to validate the theoretical models. Excellent agreement between experiment and theory is obtained.     

Evaluation of energy efficiency of fifth generation mobile systems

There has been active research worldwide to develop the next generation, i.e., fifth generation, wireless network. Next generation mobile communication networks are broadening their spectrum to higher frequency bands (above 6 GHz) to support a high data rate up to multigigabits per second. This work examines how to substantially improve energy efficiency for next fifth generation mobile communication systems. It is depicted how by limited exchange of information between neighboring base stations it is possible to maintain quality of service, over a range of traffic loads, while enabling inactive base stations to sleep. Performance of distributed energy efficient topology management schemes are compared against the system without topology management. Performance evaluation is examined using both analytical and simulation based models. Extensive numerical results show that the schemes deliver a significant energy reduction in energy consumption in the mobile network systems.     

Evaluation of reliability and safety of long-term unmaintained computer systems

In many applications such as critical life-saving systems, safety is an important design issue as well as reliability. Among various commonly-used approaches in the implementation of on-line unrepairable fault-tolerant systems, standby systems achieve the most satisfactory reliability figure, followed by duplex systems, hybrid systems and triple modular redundancy. Nevertheless, the safety figure of duplex systems is superior to that of the standby approach. In this paper, the failure rate of system modules and hard core is predicted by the M1L-HDBK-217E model, and we show that the reliability and safety figure of cold standby systems can be further dramatically improved by increasing the number of spare units. Furthermore, comparative measures such as the reliability improvement factor, the safety improvement factor and the mission time improvement factor are proposed for showing that long-term unmaintained systems have reliability and safety as high as other systems that must be repaired.     

Output feedback controllers optimal for time-multiplied performance indices

Optimal output feedback control of linear time-invariant systems with time-multiplied quadratic performance indices is derived in this letter. Expressions for performance sensitivity to parameter variations are also presented.     

Evaluation of fixed and moving primary linear induction motor systems

Linear induction motors being proposed for high-speed ground transportation may have their primaries carried on board the vehicle or embedded in the guideway. This paper evaluates various aspects, such as power requirements, power switching and controls, utilization factor, efficiency and cost, etc., for these two alternatives and provides the basic format on which relative merits of various systems can be readily evaluated. The analysis shows that, in the fixed primary system, it is economically impractical to energize sections of the roadbed substantially longer than the vehicle. Even when the primaries in the roadbed are energized in sections of minimum length, the cost of the linear induction motor and additional switching and power network for the fixed primary system is an order of magnitude higher than that for the moving primary system.