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61.
Nucleation and growth mechanisms and kinetics of crystals of an amino acid salt were investigated in a methanol‐water system by measuring and evaluating the induction time as a function of the supersaturation ratio and temperature in batch salting out crystallization experiments. Discrimination between the possible crystallization mechanisms, and estimation of the kinetic parameters were carried out using nonlinear parameter identification. The results concerning the growth mechanism obtained were checked additionally by measuring the induction time as a function of number density of seed crystals. 相似文献
62.
Self-organized public-key management for mobile ad hoc networks 总被引:6,自引:0,他引:6
In contrast with conventional networks, mobile ad hoc networks usually do not provide online access to trusted authorities or to centralized servers, and they exhibit frequent partitioning due to link and node failures and to node mobility. For these reasons, traditional security solutions that require online trusted authorities or certificate repositories are not well-suited for securing ad hoc networks. We propose a fully self-organized public-key management system that allows users to generate their public-private key pairs, to issue certificates, and to perform authentication regardless of the network partitions and without any centralized services. Furthermore, our approach does not require any trusted authority, not even in the system initialization phase. 相似文献
63.
Conducting poly(aniline‐co‐o‐anisidine) (PAS) films with different ratios of aniline units in the polymer chain were prepared by oxidative polymerization of different molar ratios of aniline and o‐anisidine in 1 M HCl using cyclic voltammetry. Due to the much higher reactivity of o‐anisidine, the structure and properties of PASs were found to be dominated by the o‐anisidine units. The polymerization of poly‐o‐anisidine and PASs followed zero‐order kinetics with respect to formation of the polymer (film thickness) and the autocatalytic polymerization of aniline was completely inhibited. In contrast to polyaniline, a decrease in the polymerization temperature was found to increase the amount of copolymer formed and its redox charge. The presence of aniline units in PASs led to a pronounced increase in the molecular weight and conductivity, and a decrease in the solubility in organic solvents. Repetitive charging/discharging cycles showed that PASs resist degradation more than polyaniline. Copyright © 2003 Society of Chemical Industry 相似文献
64.
Lopera J.M. Prieto M.J. Pernia A.M. Nuno F. 《Power Electronics, IEEE Transactions on》2003,18(3):896-906
This paper presents a method to obtain an electric model for transformers and inductors, including both frequency and geometry effects in the windings, which can be linked with existing core models. One-dimensional distributions for magnetic and electric fields are assumed, and from Maxwell's equations an equivalent electric circuit is easily obtained. This equivalent circuit has been included in analog simulators (Spice, AnalogWorkBench, Saber ...), and comparisons between measured and simulated results are shown, both in time domain and in AC sweep, which verify the model accuracy. The model described in this paper allows designers to deal with key issues in the design of high-frequency magnetic components (copper losses, leakage inductance, skin and proximity effects) by using analog simulators, which are usually more familiar to them than finite-element analysis tools. 相似文献
65.
Feng-Wen Sun Yimin Jiang Baras J.S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(1):180-190
Many issues in signal processing involve the inverses of Toeplitz matrices. One widely used technique is to replace Toeplitz matrices with their associated circulant matrices, based on the well-known fact that Toeplitz matrices asymptotically converge to their associated circulant matrices in the weak sense. This often leads to considerable simplification. However, it is well known that such a weak convergence cannot be strengthened into strong convergence. It is this fact that severely limits the usefulness of the close relation between Toeplitz matrices and circulant matrices. Observing that communication receiver design often needs to seek optimality in regard to a data sequence transmitted within finite duration, we define the finite-term strong convergence regarding two families of matrices. We present a condition under which the inverses of a Toeplitz matrix converges in the strong sense to a circulant matrix for finite-term quadratic forms. This builds a critical link in the application of the convergence theorems for the inverses of Toeplitz matrices since the weak convergence generally finds its usefulness in issues associated with minimum mean squared error and the finite-term strong convergence is useful in issues associated with the maximum-likelihood or maximum a posteriori principles. 相似文献
66.
Myers Nicholas D.; Payment Craig A.; Feltz Deborah L. 《Canadian Metallurgical Quarterly》2004,8(3):182
This study examined reciprocal relationships between collective efficacy and team performance over a season of competition in women's intercollegiate ice hockey within weekends where the opponent was constant for 2 games. Collective efficacy beliefs within 12 teams were assessed prior to both games for at least 7 weekends. Team performance indexes produced an overall measure of performance for each game. The average influence of Saturday collective efficacy on Saturday performance was moderate and positive after controlling for Friday performance. The average influence of Friday performance on Saturday collective efficacy was small and positive after removing the influence of Friday collective efficacy from Friday performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
In this paper, we describe a method for increasing the external efficiency of polymer light‐emitting diodes (LEDs) by coupling out waveguided light with Bragg gratings. We numerically model the waveguide modes in a typical LED structure and demonstrate how optimizing layer thicknesses and reducing waveguide absorption can enhance the grating outcoupling. The gratings were created by a soft‐lithography technique that minimizes changes to the conventional LED structure. Using one‐dimensional and two‐dimensional gratings, we were able to increase the forward‐directed emission by 47 % and 70 %, respectively, and the external quantum efficiency by 15 % and 25 %. 相似文献
68.
Malcolm J. Beynon 《国际智能系统杂志》2006,21(2):173-191
The granularity of an information system has an incumbent effect on the efficacy of the analysis from many machine learning algorithms. An information system contains a universe of objects characterized and categorized by condition and decision attributes. To manage the concomitant granularity, a level of continuous value discretization (CVD) is often undertaken. In the case of the rough set theory (RST) methodology for object classification, the granularity contributes to the grouping of objects into condition classes with the same condition attribute values. This article exposits the effect of a level of CVD on the subsequent condition classes constructed, with the introduction of the condition class space—the domain within which the condition classes exist. This domain elucidates the association of the condition classes to the related decision outcomes—reflecting the inexactness incumbent when a level of CVD is undertaken. A series of measures is defined that quantify this association. Throughout this study and without loss of generality, the findings are made through the RST methodology. This further offers a novel exposition of the relationship between all the condition attributes and the RST‐related reducts (subsets of condition attributes). © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 173–191, 2006. 相似文献
69.
Data mining extracts implicit, previously unknown, and potentially useful information from databases. Many approaches have been proposed to extract information, and one of the most important ones is finding association rules. Although a large amount of research has been devoted to this subject, none of it finds association rules from directed acyclic graph (DAG) data. Without such a mining method, the hidden knowledge, if any, cannot be discovered from the databases storing DAG data such as family genealogy profiles, product structures, XML documents, task precedence relations, and course structures. In this article, we define a new kind of association rule in DAG databases called the predecessor–successor rule, where a node x is a predecessor of another node y if we can find a path in DAG where x appears before y. The predecessor–successor rules enable us to observe how the characteristics of the predecessors influence the successors. An approach containing four stages is proposed to discover the predecessor–successor rules. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 621–637, 2006. 相似文献
70.
Many organisations use decision models in their processes such as tables or trees to provide decision support to their operational
divisions. For example, in fault management, customer contact centre operators usually use a decision model in the form of
prescribed interviews. Based on the answers given by customers, the operator navigates through the decision model to reach
an assessment of the problem. In order to achieve customer satisfaction and operational excellence, it is very important to
constantly monitor the performance of a decision model not only on an overall level, but also on the level of individual decisions.
In this paper we present a configurable business process analytics tool, known as the intelligent Universal Service Management
System, that constantly monitors decision data and is capable of optimising the decisions based on high-level business objectives.
We explain the various features of the software and show how it can be used to optimise decision processes. We also show how
we can easily provide a customised version to monitor the performance of provision processes. 相似文献