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91.
92.
When fixed-speed motors (fed directly at power frequency) are purchased for new installations or for replacements, the loaded shaft speed differences among motor options are either ignored or overestimated. The most common first-cut estimate is that the consumed shaft power will vary as the cube of the ratio of the motor rated nameplate speeds for centrifugal driven loads that have discharge control valves (on pressure or now control). In actuality, this is true only if the motors are loaded at approximately nameplate output. This paper discusses the true “control valve loss” factor taking into account actual speed differences among motor options. A simplified equation and figure are presented to permit quick evaluation of motor purchase alternatives for the lowest life-cycle cost based on efficiency and rated-load speed differences. NEMA standards on slip-speed variation should be made more stringent to increase the validity of speed-difference loss evaluations. Additionally, efficiency test results and loaded speed measurements for standard-efficiency and premium-efficiency 10 and 100 hp motors are presented, leading to a conclusion that standard-efficiency motors should be operated at no higher than rated voltage and that premium-efficiency motors should he operated at 5%-10% above rated voltage for best system efficiency 相似文献
93.
Applying EuroWordNet to Cross-Language Text Retrieval 总被引:1,自引:0,他引:1
Julio Gonzalo Felisa Verdejo Carol Peters Nicoletta Calzolari 《Computers and the Humanities》1998,32(2-3):185-207
We discuss ways in which EuroWordNet (EWN) can be used in multilingual information retrieval activities, focusing on two approaches to Cross-Language Text Retrieval that use the EWN database as a large-scale multilingual semantic resource. The first approach indexes documents and queries in terms of the EuroWordNet Inter-Lingual-Index, thus turning term weighting and query/document matching into language-independent tasks. The second describes how the information in the EWN database could be integrated with a corpus-based technique, thus allowing retrieval of domain-specific terms that may not be present in our multilingual database. Our objective is to show the potential of EuroWordNet as a promising alternative to existing approaches to Cross-Language Text Retrieval. 相似文献
94.
Instruction fetching is critical to the performance of a superscalar microprocessor. We develop a mathematical model for three different cache techniques and evaluate its performance both in theory and in simulation using the SPEC95 suite of benchmarks. In all the techniques, the fetching performance is dramatically lower than ideal expectations. To help remedy the situation, we also evaluate its performance using prefetching. Nevertheless, fetching performance is fundamentally limited by control transfers. To solve this problem, we introduce a new fetching mechanism called a dual branch target buffer. The dual branch target buffer enables fetching performance to leap beyond the limitation imposed by conventional methods and achieve a high instruction fetching rate 相似文献
95.
Interference Detection for Subdivision Surfaces 总被引:3,自引:0,他引:3
96.
This paper outlines approaches for assessing and classifying manufacturing and service operations in terms of their suitability for use of cross-trained (flexible) workers. We refer to our overall framework as agile workforce evaluation. The primary contributions of this paper are: (i) a strategic assessment framework that structures the key mechanisms by which cross-training can support organizational strategy; (ii) a tactical framework that identifies key factors to guide the selection of an architecture and worker coordination policy for implementing workforce agility; (iii) a classification of workforce agility architectures; (iv) a survey of a broad range of archetypical classes of worker coordination policies; (v) a survey of the literature with an operational perspective on workforce agility; and (vi) identification of opportunities for research and development of architectures for specific production environments. 相似文献
97.
Gaurang Pant Prakaipetch Punchaipetch M. J. Kim Robert M. Wallace Bruce E. Gnade 《Thin solid films》2004,460(1-2):242-246
Physical and electrical properties of hafnium silicon oxynitride (HfSixOyNz) dielectric films prepared by UV ozone oxidation of hafnium silicon nitride (HfSiN) followed by annealing to 450 °C are reported. Interfacial layer growth was minimized through room temperature deposition and subsequent ultraviolet/ozone oxidation. The capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the as-deposited and annealed HfSixOyNz are presented. These 4 nm thick films have a dielectric constant of 8–9 with 12 at.% Hf composition, with a leakage current density of 3×10−5 A/cm2 at Vfb+1 V. The films have a breakdown field strength >10 MV/cm. 相似文献
98.
The Treaty of the European Coal and Steel Community (ECSC), which expired in 2002, states in its Article 55 to promote technical and economic research with respect to the production and growing application of coal and steel. The results of funded research projects shall be made available to all representatives and partners concerned. For the European steel industry Article 55 was the basis for building up a steel research programme covering topics from raw materials to steel application and instigated a European network of researchers from the steel industry, research institutes and universities. On the basis of these research and development activities carried out by the ECSC steel research, the iron and steel industry has shown important advances in technology and environmental compatibility. Furthermore, the ECSC steel research has contributed to nearly all important technological developments. The main objective of the ECSC steel Research and Technology Development (RTD) programme was to sustain and develop the Community steel industry's competitiveness. The following report describes fundamental developments and activities within the framework of ECSC research with particular respect to hot metal production in the last 15 years. 相似文献
99.
The capabilities of Rapid Scan, a system of automated reflectance microscopy, has been extended to the actual mapping of petrographic variation across polished coal surfaces. This is accomplished through computer control of a microscope stepping stage and the storage of binary reflectance data on disc in a matrix form which permits the proper spatial arrangement of values to be re-created. The maps depict lithotype variation, and the distribution of mineral occurrences, cracks and cleat. An image processor can be employed in further map analysis such as the compilation of reflectance profiles from selected areas. 相似文献
100.
An improved digital image processing procedure is developed to extract the size and shape of the plastic zone formation at the tip of a notched metal specimen based on the characteristics of the variation of intensity in a digitized image. The result is compared with the result from finite element analysis, and with that from a previously developed image processing procedure. Comparison shows that this method provides a faster and more accurate result than previously. 相似文献