Components In Parallel Research Articles

An Application and Characteristic Analysis of MOGA for Bi-Objective Optimal Component Allocation Problem in Series-Parallel Redundant System

We discuss a solution method based on evolutionary technology for the optimal component allocation problem in a series-parallel redundant system. A series-parallel system consists of subsystems that are connected in series and each subsystem consists of interchangeable components in parallel. There are some heuristic methods to approximately solve the optimal component allocation problem for series-parallel systems. We have formulated this problem as a multi-objective optimization problem minimizing the system cost and maximizing the system reliability, and proposed an algorithm that obtains the exact solutions (Pareto solutions) of the problems in an efficient way. Because this problem is one of the NP-complete problems, it is difficult to obtain the optimal solution for the large-scale problems and methods that obtain the exact solutions are not known. The algorithm utilizes the depth-first search method to eliminate useless searches and employs the branch-and-bound method to obtain the Pareto solutions. According to the results of our numerical experiments, the algorithm searches the Pareto solutions in practical execution time for not-so-large-scale problems. In order to solve larger-scale problems, we propose a multi-objective genetic algorithm (MOGA). We evaluate the ability of the MOGA by comparison with the exact solution method by using various scale problems. Through those experiments, we discuss the characteristics of this problem and analyze the effectiveness of our method. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(9): 7–16, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10100

Strategic defense and attack for reliability systems

This article illustrates a method by which arbitrarily complex series/parallel reliability systems can be analyzed. The method is illustrated with the series–parallel and parallel–series systems. Analytical expressions are determined for the investments and utilities of the defender and the attacker, depend on their unit costs of investment for each component, the contest intensity for each component, and their evaluations of the value of system functionality. For a series–parallel system, infinitely many components in parallel benefit the defender maximally regardless of the finite number of parallel subsystems in series. Conversely, infinitely many components in series benefit the attacker maximally regardless of the finite number of components in parallel in each subsystem. For a parallel–series system, the results are opposite. With equivalent components, equal unit costs for defender and attacker, equal intensity for all components, and equally many components in series and parallel, the defender always prefers the series–parallel system rather than the parallel–series system, and converse holds for the attacker. Hence from the defender's perspective, ceteris paribus, the series–parallel system is more reliable, and has fewer “cut sets” or failure modes.

A Complete Spectral Polarimeter Design for Lightwave Communication Systems

The authors describe a fast spectral polarimeter operating in the lightwave communications band capable of measuring both state-of-polarization and degree-of-polarization of hundreds (up to thousands) of spectral components in parallel within milliseconds. In this paper, the design incorporates fast switching ferroelectric liquid crystals for polarization component selection on the 100-mus scale. Dispersion elements and an arrayed detector are used for wavelength-parallel sensing. Bandwidth of coverage can be scaled from a single wavelength-division multiplexed channel to more than 100 nm, and 256 spectral polarization measurements in under 1 ms are verified. Finally, a calibration algorithm is used to minimize measurement error. This instrument offers unprecedented sensing capability relevant to the monitoring and compensation of polarization-related impairments in high-speed lightwave communications

A power-based adaptive method for eigenanalysis without square-root operations

This paper describes an adaptive eigenanalysis algorithm for estimating the eigenstructure of a sample covariance matrix. A minimization nonquadratic criterion is formulated by exploring the relationship of eigenvalues between the covariance matrix and its inverse matrix. A quasi-Newton approach is proposed to perform the task of minimization. It is shown that the new algorithm can be acted as another power method but without square-root operation. This approach is well-suited to parallel implementation when it is used for iterative estimation of multiple principal components by a deflation method. A unified modular architecture is developed for the analysis of both principal and minor components. Simulation experiments are carried out with both stationary and nonstationary data. The results show that the proposed method is capable of extracting multiple principal components in parallel with fast convergence speed and high tracking accuracy.

RELIABILITY ANALYSIS OF LARGE SYSTEMS WITH DEPENDENT COMPONENTS

Dependent failures of components in parallel and parallel-series systems are defined. Reliability functions of parallel and parallel-series systems composed of dependent components and their limit forms are determined. The results are applied to the reliability evaluation of an exemplary parallel system and to the shipyard rope transportation parallel-series system.

On a generalized k-out-of-n system and its reliability

A consecutive-k-out-of-n system is a system with n components arranged either linearly or circularly, which fails if and only if at least k consecutive components fail. An (n, f, k) system further requires that the total number of failed components is less than f for the system to be working. Here we consider a more general system consisting of N modules with the ith module-composed of n i components in parallel; the system fails if and only if there exist at least f failed components or at least k consecutive failed modules. In this paper, some formulae for the reliability of such a generalized k-out-of-n system are derived for both the linear and the circular cases. The recursive formulae established here can be easily computed. Many existing results are also shown to be special cases of the results obtained in this paper. Furthermore, we investigate some component importance properties.

An Ant Colony Optimization Algorithm for the Redundancy Allocation Problem (RAP)

This paper uses an ant colony meta-heuristic optimization method to solve the redundancy allocation problem (RAP). The RAP is a well known NP-hard problem which has been the subject of much prior work, generally in a restricted form where each subsystem must consist of identical components in parallel to make computations tractable. Meta-heuristic methods overcome this limitation, and offer a practical way to solve large instances of the relaxed RAP where different components can be placed in parallel. The ant colony method has not yet been used in reliability design, yet it is a method that is expressly designed for combinatorial problems with a neighborhood structure, as in the case of the RAP. An ant colony optimization algorithm for the RAP is devised & tested on a well-known suite of problems from the literature. It is shown that the ant colony method performs with little variability over problem instance or random number seed. It is competitive with the best-known heuristics for redundancy allocation.

Geomagnetic disturbances and their relationship to Interplanetary shock parameters

We identify 107 fast, forward‐propagating interplanetary shocks observed by the Wind spacecraft from 1995–2000 to examine the influence of shock parameters on geomagnetic disturbances following the shock arrival at Earth. We find that the angle between the shock front normal and the interplanetary magnetic field (IMF) direction might play a useful role in forecasting the severity of geomagnetic storms occurring within 48 hours from the shock passage. Quasi‐perpendicular shocks, i.e. those nearly orthogonal to the IMF direction, constrain IMF components in the plane parallel to the shock front, making it more likely to produce southward IMF. We demonstrate that, regardless of the shock driver, about 40% of forward IP shocks result in intense magnetic storms when the shock normal is almost perpendicular to the IMF, compared to about 10–15% of shocks with normals not perpendicular to the IMF direction.

A two-phase linear programming approach for redundancy allocation problems

Provision of redundant components in parallel is an efficient way to increase the system reliability, however, the weight, volume and cost of the system will increase simultaneously. This paper proposes a new two-phase linear programming approach for solving the nonlinear redundancy allocation problems subject to multiple linear constraints. The first phase is used to approximately allocate the resource by using a general linear programming, while the second phase is used to re-allocate the slacks of resource by using a 0-1 integer linear programming. Numerical results demonstrate the effectiveness and efficiency of the proposed approach.

Performability of Two Modules in Series

The paper presents a combined model of reliability and performance (performability model) of two modules in series, each has C components in parallel. The objective of the paper is to illustrate the effect of the reliability on the performance. The paper emphasizes homogeneous continuous-time Markov process and queueing approach for reliability and performance models respectively. A numerical example when C=2 is provided to illustrate the results.

PRIOR RELIABILITY ASSESSMENTS BASED ON COHERENT IMPRECISE PROBABILITIES

The paper describes an approach to obtaining prior imprecise reliability values of components and systems. The mathematical basis of the approach is the theory of coherent imprecise probabilities. The procedure of prior imprecise probability elicitation is based on analogical reasoning, and two cases of precise and imprecise reliabilities of prototypes are considered. Cases of combining different reliability judgements for the same component are analyzed. The remainder of the paper is devoted to imprecise reliability assessments of different system structures: components in parallel, in series and in series-parallel. The formulae obtained allow getting the lower and upper probabilities without the assumption of conditional independence. What we can expect from the use of this new tool is briefly discussed.

Reliability Analysis of Systems with Time-Varying Failure Rates

A non-homogeneous Markov model is used to obtain closed form solutions of the state probabilities and the reliability of M modules in series where each module has N m components in parallel. The components have exponential time-varying failure rates which depend on the module. If the failure rates are independent of the modules the results are extended to a K -out-of- N : G system and series-parallel. Examples of assuming the Weibull distributions are presented to illustrate the results.

Activity-dependent decay of early LTP revealed by dual EPSP recording in hippocampal slices from young rats.

The early maintenance of long-term potentiation (LTP) was studied in the CA1 region of hippocampal slices from 12- to 18-day-old rats in a low-magnesium solution (0.1 mM). The alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor-mediated components of the field excitatory postsynaptic potential were estimated in parallel using early and late measurements of the composite potential. At the normal test stimulus frequency of 0.1 Hz, LTP was seen initially as a predominant increase in the AMPA component, but converted, via a substantial decay of this component and a gradual growth of the NMDA component, into nearly equal changes of the two components. Interrupting the test stimulation for 10 min, changing the test stimulus frequency to 1/60 Hz after LTP induction, or using a test stimulus frequency of 1/60 Hz during the entire experiment significantly reduced the decay of the potentiation of the AMPA component while enhancing the potentiation of the NMDA one. The ratio between the magnitudes of the two excitatory postsynaptic potential (EPSP) components showed a decaying time course that was independent of the manipulations used. Application of the NMDA antagonist D(-)-2-amino-5-phosphonopentanoic acid (50 microM) after LTP induction stabilized the LTP of the AMPA component until washout was started. On the other hand, the phosphatase inhibitor okadaic acid (1 microM) resulted in decay of the potentiation of both EPSP components back to around baseline and altered the time course of the ratio between the components. Our results show that the early maintenance of LTP is controlled in an activity-dependent and NMDA-dependent manner. This process accelerates the decay of LTP of both AMPA and NMDA components in parallel, suggesting that it is similar to homosynaptic long-term depression, although it operates at the normal test stimulus frequency. The data support a scenario in which LTP ensues as a selective AMPA receptor modification and subsequently converts to another modification, possibly a presynaptic one.

Performance analysis of parallel simulation on distributed systems

This paper presents an analytical model to evaluate the performance of parallel simulation on distributed computing platforms. The proposed model is formalized by two important time components in parallel and distributed processing: computation time and communication time. A conservative parallel simulation of multistage interconnection networks is used as an example in our analytical model. Performance metrics such as elapsed time, speedup and simulation bandwidth associated with different schemes for partitioning/mapping parallel simulation onto distributed processors are evaluated. Our mathematical analysis identifies the major constituents of simulation overheads in these mapping strategies necessary for improving parallel simulation efficiency. We also show that a perfectly balanced workload distribution may not necessarily translate into better performance. On the contrary, we have shown that a balanced mapping of workload may increase communication overheads resulting in a longer simulation elapsed time. Our performance model has been validated against implementation results from a parallel simulation model. The analytical framework is also practical to evaluate the runtime efficiency of other simulation applications which are based on the conservative paradigm.

The RPR method for the doorstopper technique: Four or six stress components from one or two boreholes

The importance of continuosly recording strain (or displacement) recover during stress relief when conducting in situ stress measurements has been recognized by many authors as a means of assessing the quality of a measurement. This paper describes an important new use for these strain recovery curves, as four components of the stress tensor can now be obtained from one modified doorstopper stress measurement using a parameter called the recovered to peak strain invariant ratio (RPR). Modifications made to the standard doorstopper cell and to the standard field procedure are briefly described. These allow continuous recording of strain recovery while stress is being relieved, as well as the monitoring of temperature at the rock-cell interface. Then, a description of the finite element modelling allowing the production of curves relating the far field stress components in a plane parallel to the measurement plane to the stress component normal to this plane is given. Validation of the model is achieved by laboratory stress measurement simulations. Finally, comments on preliminary results of this method applied to the borehole deformation gauge stress measurement technique are made.

Magnetogravitational Instability of Anisotropic Plasma with Finite Ion Larmor and Generalized Polytrope Law

The effect of finite ion Larmor radius corrections on the propagation of small perturbations through self gravitating, anisotropic system with generalized polytrope law is investigated. The polytrope laws are considered for the pressure components in parallel and perpendicular directions to the magnetic field. The polytrope model proposed by Abraham-Shranuer can be reduced to CGL equations with double adiabatic equations of state and MHD set of equations with isothermal equation of state. The effects of FLR and polytrope indices are discussed on the gravitational, firehose and mirror instability. The critical Jeans wave numbers are found to depend on polytropic indices and derived for CGL and MHD cases. The FLR corrections are found effective in shorter wave length region and produce stabilizing influence. The condition of mirror instability is uninfluenced by FLR but dependent on polytropic indices.

Reliability and redundancy apportionment using crisp and fuzzy multiobjective optimization approaches

Abstract The reliability of a multistage system with several components in each stage can be improved either by using more reliable components, or by adding redundant components in parallel in any stage. In many practical situations where reliability enhancement is involved, the decision making is complicated because of the presence of several mutually conflicting goals. For example, in the reliability based design of a system, the designer may be required to maximize the reliability and minimize the cost, weight or volume. This work considers the problem of reliability allocation for multistage systems with components having time-dependent reliability. Two multiobjective optimization techniques are presented, coupled with heuristic procedures, to solve the mixed integer nonlinear programming problems. A generalization of the problem in the presence of vague information results in an ill-structured reliability apportionment problem. The solution of such multiobjective problems is also presented in the present work using the techniques of fuzzy optimization.

The bovine endothelin receptor has an apparent molecular weight of 43 000

In crosslinking experiments, [ 125I]endothelin-1 was treated with N-hydroxysuccinimidyl-4-azidobenzoate, purified by HPLC, allowed to bind to bovine aortic membranes and then photoactivated. Autoradiography of sodium dodecyl sulfate polyacrylamide gel electrophoretograms of the products of this reaction showed that a component of apparent M r = 42 000 was specifically labelled by endothelin-1 under reducing conditions. Under nonreducing conditions, a small amount of 125I-labelled endothelin-1 specifically labelled a component of apparent M r = 45 900 in the absence of crosslinking agent. Non-radiolabelled endothelin analogues with a wide range of binding affinities inhibited specific labelling of the M r = 42 000 and 45 900 components in parallel over the concentration ranges which inhibited binding of radiolabelled endothelin. Specific labelling of these components was also observed in parallel in membranes from bovine heart and kidney. The components labelled in the presence and absence of crosslinker appear to be the same, and the small difference in apparent M r in the labelled components is likely due to a difference in conformational constraints arising from the two labelling processes, with a true, corrected M r of 43 400. Since the specific labelling of this component is related to physiologically relevant binding in several bovine tissues, we conclude that it is a component of the bovine endothelin receptor.

A Comment on Quinn and Hastings: Extinction in Subdivided Habitats

Conservation BiologyVolume 2, Issue 3 p. 290-292 A Comment on Quinn and Hastings: Extinction in Subdivided Habitats MICHAEL E. GILPIN, MICHAEL E. GILPIN Department of Biology (C-016) University of California at San Diego La Jolla, CA 92093, USA.Search for more papers by this author MICHAEL E. GILPIN, MICHAEL E. GILPIN Department of Biology (C-016) University of California at San Diego La Jolla, CA 92093, USA.Search for more papers by this author First published: September 1988 https://doi.org/10.1111/j.1523-1739.1988.tb00186.xCitations: 34AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume2, Issue3September 1988Pages 290-292 RelatedInformation

Effect of thyroid hormones on the activity of hepatic glucose-6-phosphatase in fed and fasted rats.

The action of thyroid hormones on hepatic glucose-6-phosphatase was studied in rats. Fed and 24-h fasted rats received T3 (10 micrograms/day) or T4 (25 micrograms/day) 1 h, 1 or 3 days before sacrificing. In addition a group of fed rats was treated with T4 for 7 and 14 days. The glucose-6-phosphatase activity was measured in the isolated microsomes prepared from the liver. The intactness of the microsomal preparation was checked using 2 mM mannose-6-phosphate as a substrate. In fed rats a single injection of T3 or T4 augmented the activities of the translocase and hydrolase components of glucose-6-phosphatase provided that the rats were killed 24 h after the administration of hormone. This effect was more pronounced in animals treated for 3-14 days. As expected, fasting per se increased the activities of both components of the enzyme. Moreover, in fasted rats treatment with T3 and T4 for 3 days further augmented the activities of the translocase and the hydrolase components of glucose-6-phosphatase. In fed animals T3 and T4 increased the latency of the enzyme whereas in fasted animals thyroid hormones increased the activities of the translocase and hydrolase components in parallel, maintaining the level of latency of the enzyme system. Administration of T3 and T4 increased blood glucose level in fasted rats after one day, while in fed rats a significant hyperglycaemia appeared after 7-14 days of treatment. In conclusion, T3 and T4 increase the activities of the translocase and hydrolase components of hepatic glucose-6-phosphatase in fed and fasted rats.(ABSTRACT TRUNCATED AT 250 WORDS)