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981.
Fu-Lai Chung Tong Lee 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》1998,28(6):919-924
Since Sanchez's seminal paper on fuzzy relational equations, both their theories and applications have been continuously exploited by researchers. However, the solvable conditions of a system of fuzzy relational equations, also known as a fuzzy relational system (FRS), are still poorly established and their relationship with the methods for obtaining approximate solutions are unclear. When the FRS is adopted to model a fuzzy system, most of the existing identification algorithms focus on parameter estimation and less on the structure identification. In this paper, these two issues are addressed. New theoretical understandings on solving a system of fuzzy relational equations exactly and approximately are presented and their implications on the use of FRS to encode fuzzy rulebases are highlighted. Based upon the guided evolutionary simulated annealing (GESA) algorithm, an evolutionary identification formulation called EVIDENT capable for both parameter and structure identifications in fuzzy system models is proposed. As demonstrated by the simulation results, the new algorithm not only is effective in determining the structure of the systems, but also identifies a better parametric solution, as compared with that of the existing FRS identification algorithms. 相似文献
982.
Application of fuzzy logic structures in CAD of digital electronics substantially improves quality of design solutions by providing designers with flexibility in formulating goals and selecting tradeoffs. In addition, the following aspects of a design process are positively impacted by application of fuzzy logic: utilization of domain knowledge, interpretation of uncertainties in design data, and adaptation of design algorithms. We successfully applied fuzzy logic structures in conjunction with constructive and iterative algorithms for selecting of design solutions for different stages of the design process. We also introduced fuzzy logic software development tool to be used in CAD applications 相似文献
983.
Kyung-OhLee Jun-HoPark Yoon-YoungPark 《计算机科学技术学报》2004,19(6):0-0
When designing a multimedia server, several things must be decided: which scheduling scheme to adopt, how to allocate multimedia objects on storage devices, and the round length with which the streams will be serviced. Several problems in the designing of large-scale multimedia servers are addressed, with the following contributions: (1) a striping scheme is proposed that minimizes the number of seeks and hence maximizes the performance; (2) a simple and efficient mechanism is presented to find the optimal striping unit size as well as the optimal round length, which exploits both the characteristics of VBR streams and the situation of resources in the system; and (3) the characteristics and resource requirements of several scheduling schemes are investigated in order to obtain a clear indication as to which scheme shows the best performance in realtime multimedia servicing. Based on our analysis and experimental results, the CSCAN scheme outperforms the other schemes. It is believed that the results ar 相似文献
984.
Dong-Geun Lee You Hwan Lee Sunghak Lee Chong Soo Lee Sun-Moo Hur 《Metallurgical and Materials Transactions A》2004,35(10):3103-3112
Effects of microstructural morphology on dynamic deformation behavior and ballistic impact properties of Ti-6Al-4V alloy plates
were investigated in this study. Dynamic torsional and ballistic impact tests were conducted on equiaxed and bimodal microstructures,
which were processed by different heat treatments, and then the test data were analyzed in relation to microstructures and
tensile properties. According to the dynamic torsional test data, maximum shear stress and fracture shear strain of the bimodal
microstructure were higher than those of the equiaxed microstructure, and the possibility of the adiabatic shear band formation
was more likely in the equiaxed microstructure than in the bimodal microstructure. In the ballistically impacted region of
the equiaxed microstructure, a number of adiabatic shear bands and cracks were observed to be formed along plastic flow lines,
and delamination occurred because of cracking along the flow lines or shear bands. In the case of the bimodal microstructure,
shear bands were found in limited areas near the penetrated surface without occurring delamination, and their number was smaller
than that of the equiaxed microstructure. Thus, ballistic performance of the bimodal microstructure was better than that of
the equiaxed microstructure, which was consistent with the dynamic torsional test results. 相似文献
985.
G. Y. Kim L. M. He J. D. Meyer W. Y. Lee A. Quintero J. A. Haynes 《Metallurgical and Materials Transactions A》2004,35(11):3581-3593
A laboratory-scale chemical vapor deposition (CVD) reactor was used to perform “continuous” Hf doping experiments while the
surface of a single-crystal Ni alloy was being aluminized to form an aluminide (β-NiAl) coating matrix for 45 minutes at 1150 °C. The continuous doping procedure, in which HfCl4 and AlCl3 were simultaneously introduced with H2, required a high HfCl4/AlCl3 ratio (>∼0.6) to cause the precipitation of Hf-rich particles (∼0.1 μm) at grain boundaries of the coating layer, with the overall Hf concentration of ∼0.05 to 0.25 wt pct measured in the coating
layer by glow-discharge mass spectroscopy (GDMS). Below this ratio, Hf did not incorporate as a dopant into the growing coating
layer from the gas phase, as the coating matrix appeared to be “saturated” with other refractory elements partitioned from
the alloy substrate. In comparison, the Hf concentration in the aluminide coating layer formed on pure Ni was in the range
of ∼0.1 wt pct, which was close to the solubility of Hf estimated for bulk NiAl. Interestingly, the segregation of Hf and
the formation of a thin γ′-Ni3Al layer (∼0.5 μm) at the coating surface were consistently observed for both the alloy and pure-Ni substrates. The formation of the thin
γ′-Ni3Al layer was attributed to an increase in the elastic strain of the β-NiAl phase, associated with the segregation of Hf as well as other refractory alloying elements at the coating surface. This
phenomenon also implied that the coating layer was actually growing at the interface between the γ′-Ni3Al layer and the β-NiAl coating matrix, not at the gas/coating interface, during the early stage of the coating growth. 相似文献
986.
Cheng-Hsun Hsu Shen-Chih Lee Hwei-Yuan Teng 《Metallurgical and Materials Transactions A》2004,35(2):471-480
This research studied the effects of heat treatment and testing temperature on fracture mechanics behavior of Si-modified
CA-15 martensitic stainless steel (MSS), which is similar to AISI 403 grade stainless steel, which has been widely used in
wall and blanket structures and in the pipe of nuclear power plant reactors, turbine blades, and nozzles. The results indicated
that fracture toughness of low-Si CA-15 MSS is better than that of AISI 403. The specimens of the low-Si CA-15 MSS after austenitization
at 1010 °C and then tempering at 300 °C have higher plane-strain fracture toughness (K
IC
) values for both 25 °C and −150 °C testing temperatures. However, the specimens tested at 150 °C cannot satisfy the plane-strain
fracture toughness criteria. The fatigue crack growth rate is the slowest after austenitization at 1010 °C for 2 hours and
tempering at 400 °C. Observing the crack propagation paths using a metallographic test, it was found that the cracking paths
preferred orientation and branched along ferrite phase, owing to martensite-phase strengthening and grain-boundary-carbide
retarding after 300 °C to 400 °C tempering. Also, transmission electron microscopy (TEM), scanning electron microscopy (SEM),
and X-ray diffraction analysis were performed to correlate the properties attained to the microstructural observation. 相似文献
987.
This paper presents an automatic construction of Korean WordNet from pre-existing lexical resources. We develop a set of automatic word sense disambiguation techniques to link a Korean word sense collected from a bilingual machine-readable dictionary to a single corresponding English WordNet synset. We show how individual links provided by each word sense disambiguation method can be non-linearly combined to produce a Korean WordNet from existing English WordNet for nouns. 相似文献
988.
Recently there have been attempts in several research areas at efficiently utilizing the resources of mobile computers. Considering the properties in mobile computing environments, push-based data dissemination systems have lately attracted considerable attention. However, skewed access patterns among mobile clients makes response time worse, and they prefer to send data requests to the server explicitly through an uplink channel. A broadcast supporting an uplink channel is called a hybrid broadcast. In this paper, we devise new transaction processing algorithms for hybrid broadcasts. It is assumed that data objects that the server maintains are divided into Push_Data for periodic broadcasting and Pull_Data for on-demand service. That is, clients have to explicitly request data objects in Pull_Data. Maintaining transactional consistency in this environment without much additional cost is our main concern. Finally, we evaluate performance behavior through simulation study.Received: 15 November 2002, Published online: 5 August 2004This work was done as part of the Information & Communication Fundamental Technology Research Program, supported by the Ministry of Information & Communication in the Republic of Korea. 相似文献
989.
Discovery of fuzzy temporal association rules 总被引:1,自引:0,他引:1
Wan-Jui Lee Shie-Jue Lee 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2004,34(6):2330-2342
We propose a data mining system for discovering interesting temporal patterns from large databases. The mined patterns are expressed in fuzzy temporal association rules which satisfy the temporal requirements specified by the user. Temporal requirements specified by human beings tend to be ill-defined or uncertain. To deal with this kind of uncertainty, a fuzzy calendar algebra is developed to allow users to describe desired temporal requirements in fuzzy calendars easily and naturally. Fuzzy operations are provided and users can define complicated fuzzy calendars to discover the knowledge in the time intervals that are of interest to them. A border-based mining algorithm is proposed to find association rules incrementally. By keeping useful information of the database in a border, candidate itemsets can be computed in an efficient way. Updating of the discovered knowledge due to addition and deletion of transactions can also be done efficiently. The kept information can be used to help save the work of counting and unnecessary scans over the updated database can be avoided. Simulation results show the effectiveness of the proposed system. A performance comparison with other systems is also given. 相似文献
990.
An adaptive mechanism for video partitioning in the transform domain is proposed. Different quantitative measures for motion complexity and activity levels in a scene are defined, based on which a video scene can be consistently categorised into identifiable classes. Further, the video quality, as measured by the mean square error (MSE) is related to certain parameters used in video partitioning. Adaptability is realized by tailoring the parameters of the video partitioning algorithm to the specific characteristics of the video scene, as embodied in the video scene class and the video quality. Experimental results are included. 相似文献