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排序方式: 共有186条查询结果,搜索用时 15 毫秒
21.
Pattern Analysis and Applications - This paper proposes a novel classifier based on the theory of Learning Automata (LA), reckoned to as PolyLA. The essence of our scheme is to search for a...  相似文献   
22.
Water Resources Management - As water scarcity and drought become more common, planning to avoid their consequences becomes crucial. Measures to prevent the impact of new climate conditions are...  相似文献   
23.
In this paper we describe an object–oriented framework for developing enterprise models of Architecture, Engineering, Construction projects, and a methodology for formalizing these models such that they can be used for discrete event simulation of information processing and coordination in project execution. The simulation results can be used to predict the probable effects of carrying out proposed changes in planning and managing projects.
In our enterprise modeling framework we represent engineering design projects in terms of deliverables (requirements and solutions), plans (activities and process relations), and organization (participants and organizational relations). The resulting project model is the starting point for identifying coordination requirements between project team participants. Our methodology uses matrix techniques derived from qualtiy function deployment (QFD) to identify interactions between project requirements and solutions and calculate measures of product complexity . We then describe information flow between project activities in a similar matrix and calculate measures of process uncertainty . Finally, we identify the responsibilities of project team members and use a matrix to point out organizational interdependencies .
We apply our framework and methodology to model and simulate engineering design for a major extension of an electrical power substation. Our simulation results demonstrate how project performance is contingent on the fit between the project policies and the objectives and preferences of the project team.  相似文献   
24.
AMOS is a mediator system that supports passive (non-intrusive) integration of data from heterogeneous and autonomous data sources. It is based on a functional data model and a declarative functional query language AMOSQL. Foreign data sources, e.g., relational databases, text files, or other types of data sources can be wrapped with AMOS mediators, making them accessible through AMOSQL. AMOS mediators can communicate among each other through the multi-database constructs of AMOSQL that allow definition of functional queries and OO views accessing other AMOS servers. The integrated views can contain both functions and types derived from the data sources. Furthermore, local data associated with these view definitions may be stored in the mediator database. This paper describes AMOS' multi-database query facilities and their optimization techniques. Calculus-based function transformations are used to generate minimal query expressions before the query decomposition and cost-based algebraic optimization steps take place. Object identifier (OID) generation is used for correctly representing derived objects in the mediators. A selective OID generation mechanism avoids overhead by generating in the mediator OIDs only for those derived objects that are either needed during the processing of a query or have associated local data in the mediator database. The validity of the derived objects that are assigned OIDs and the completeness of queries to the views are guaranteed by system generated predicates added to the queries.  相似文献   
25.
The paper proposes that 1/f noise in materials and devices under non-equilibrium conditions is of electromagnetic origin rather than being related to charge carriers. For samples represented by simple resistors the analysis shows that the noise is due to the discrete nature of photons constituting the impinging electromagnetic flux from the source feeding the resistor. The paper presents detailed analysis of the external and internal electromagnetic fields of the resistor environment, with appropriate interpretation in terms of discrete photons. From quantum theory photons are known to retain their energy under interactions in linear environments. This property implies a departure from macroscopic electromagnetics in that photons cannot be partially transmitted and partially reflected, a phenomenon requiring appropriate modifications of boundary conditions at the resistor surface. These special demands call for inclusion of a supplementary internal resistor mode, serving as a lossless idler which is active only for matching purposes. At the resistor terminals the impinging photons give rise to excitation of RF current and voltage noise with an exact 1/f frequency distribution, which is in agreement with all available experimental measurements. The paper presents detailed formulae for noise spectral densities under general drive conditions from DC and RF sources of arbitrary internal resistance. The presented theoretical noise formulae have the same form as earlier empirical formulae for 1/f noise. With an RF source at frequency f0 the analysis predicts noise with 1/|f-f0| frequency distribution, which is compatible with available experimental observations.  相似文献   
26.
Sorption of P to the filter material Filtralite-P was examined at a small, medium and large scale. In the small- and meso-scale laboratory models, the sorbed amount of total phosphorus (P) was heterogeneously distributed with more P sorbed in the inlet zone and the bottom layers. The full-scale system had, on the other hand, the highest sorbed concentration in the outlet region. The overall P sorption capacity of the material was 8030, 4990 and 521 mg P kg(-1) Filtralite-P for Box 1, Box 2 and meso scale, respectively. This equals 4.4, 2.8 and 0.29 kg P m(-3) material, respectively. However, the maximum sorption capacities found were 2500, 3887 and 4500 mg P kg(-1) Filtralite-P for the two small-scale box systems and the meso-scale container, respectively. In the full-scale system the overall P sorption capacity of the material was 52 mg P kg(-1) Filtralite-P (0.029 kg P m(-3) Filtralite-P with a maximum sorbed amount of P of 249 mg P kg(-1). Results from both the small- and meso-scale system show that when a constructed wetland (CW) is saturated, i.e. when the outlet concentration has reached its maximum allowed concentration of 1.0 mg P l(-1), only parts of the filter material will have reached the sorption capacity. Sequential extractions of Filtralite-P showed that the loosely bound P, Ca-P and Al-P were the primary P sorption pools both in the small-scale models and in the full-scale CW. However, the proportion of these three fractions varied with time and change in pH. A white product precipitated in the outlet zone of both the small-scale box models as well as the onsite CW. The surface of these precipitation particles was identified by X-ray diffraction and SEM method as CaCO3 and precipitated Ca- and Mg-phosphates.  相似文献   
27.
The search for plastic materials suitable for hot water service has gone on for several years with only partial success, because technical problems are usually overcome only at high cost. One of the most promising developments, however, is a polythene pipe with a cross-linked molecular structure, known as PEX pipe. Here, a scientist at the Norwegian Building Research Institute, recounts the testing procedures which are helping to verify the appropriate service conditions for this newer material.  相似文献   
28.
Abstract

Two proposed ionic compounds, NH4O2 and NH4O3, are discussed in terms of several properties related to energetic performance. These include oxygen content, moles of gas produced and heat released upon decomposition, and specific impulse. The heat release was calculated in each instance using the predicted lattice energy, which was obtained from the computed electrostatic potential on the surface of the negative ion. NH4O2 is found to be superior to HMX in each property considered, while NH4O3 is better than HMX in some and comparable in the others.  相似文献   
29.
New innovations that can transform societies and improve life for people are increasingly being asked for. Unfortunately, some avenues of research indicate that users of these new innovations may be inaccurate when they predict or remember the value of such new offerings. For example, the rapid development of new ICT services in areas such as health care may imply opportunities for better life conditions and well-being, but may also involve complicated predictions for users about the value they will create. New innovations may face adoption difficulties if users make inaccurate predictions or remember falsely the value that such innovations might have. In this study, 48 nurses predicted, experienced, and remembered the value of a new ICT service they used to diagnose an external skin lesion on a patient. Results showed significant differences between predicted and experienced value as well as between a service with high technical quality and the same service with lower technical quality; the value was underestimated at the time of prediction, as compared to actual experience, and the value of a high-quality ICT service was substantially more underestimated than the value of a low-quality ICT service. The results provide a novel and comprehensive understanding of how employees predict and experience the value of ICT service innovations.  相似文献   
30.

Context

Comparing and contrasting evidence from multiple studies is necessary to build knowledge and reach conclusions about the empirical support for a phenomenon. Therefore, research synthesis is at the center of the scientific enterprise in the software engineering discipline.

Objective

The objective of this article is to contribute to a better understanding of the challenges in synthesizing software engineering research and their implications for the progress of research and practice.

Method

A tertiary study of journal articles and full proceedings papers from the inception of evidence-based software engineering was performed to assess the types and methods of research synthesis in systematic reviews in software engineering.

Results

As many as half of the 49 reviews included in the study did not contain any synthesis. Of the studies that did contain synthesis, two thirds performed a narrative or a thematic synthesis. Only a few studies adequately demonstrated a robust, academic approach to research synthesis.

Conclusion

We concluded that, despite the focus on systematic reviews, there is limited attention paid to research synthesis in software engineering. This trend needs to change and a repertoire of synthesis methods needs to be an integral part of systematic reviews to increase their significance and utility for research and practice.  相似文献   
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