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排序方式: 共有1678条查询结果,搜索用时 871 毫秒
91.
H. Wang S. To C.Y. Chan C.F. Cheung W.B. Lee 《International Journal of Machine Tools and Manufacture》2010,50(3):241-252
This paper presents a theoretical and experimental investigation of the influence of tool-tip vibration on surface generation in single point diamond turning (SPDT). Although it is well known that the relative vibration between the tool and the workpiece plays an important role in the surface generation in single-point diamond turning, most of the prior work has been focused on studying the relative tool-work vibration in the infeed (thrust force) direction while the significant contribution of the effect of the tool-tip vibration in the cutting force direction has been overlooked. In the present study, two characteristic peaks (twin peaks) are identified and found to be corresponding to the tool-tip vibrations by power spectrum density (PSD) analyses. The vibrations possess the features of small amplitude but high frequency. A physical model is proposed to capture the dominant factor based on the characteristic and it reveals that the twin peaks are attributed by the impact between the tool tip and workpiece and the process damping effect. Hence, a geometric model of surface roughness is proposed to take account of tool-tip vibration and it is verified through a series of experiments. The simulation results have been found to agree well with the experimental results. 相似文献
92.
S. O. Cheung C. M. Tam I. Ndekugri F. C. Harris 《Construction Management & Economics》2013,31(3):281-294
The use of project dispute resolution satisfaction (DRS) as a project success measurement responds to the increasing concern over the spread of the dispute epidemic within the construction industry in Hong Kong. The DRS of a project is considered as favourable where disputes are resolved within the site level. With the use of 48 project data sets and the technique of multivariate discriminant analysis, a discriminant model function was derived to classify projects into favourable DRS and adverse DRS. The multivariate discriminant analysis model function identified eight discriminating variables, among which the degree of design changes offered the highest separation power. The reliability of the discrminating variables was reinforced by a separate relative importance index study. Through the use of principal component factor analysis, these variables were grouped into three factors generically described as substantive influence, facilitation and indirect influence. 相似文献
93.
Development of a re-configurable ambisonic decoder for irregular loudspeaker configuration 总被引:1,自引:0,他引:1
This study reports a heuristic genetic algorithm to determine the decoding parameters in a first-order ambisonic system for reconstructing a three-dimensional sound field with an arbitrary quad speaker configuration. On this basis, a hardware prototype has been developed using a field programmable gate array (FPGA) to decode ambisonic signals that are encoded in the standard B-format. To allow direct coupling with digital audio sources, the input and output channels of the decoder are implemented with the I2S interface. Evaluations reveal that the decoding parameters derived by this method are superior to existing approaches in terms of flexibility in loudspeaker configuration and optimisation of some of the essential factors in surround sound reconstruction. 相似文献
94.
Zan Yang Shuping Wu Hiu Ying Cheung 《Journal of Housing and the Built Environment》2017,32(2):231-252
The emerging notion of emissions inequality expands the idea of sustainability by incorporating economic opportunity as well as social needs and rights into environmental costs and benefits. In China, increasing inequality among urban households in terms of both income and housing wealth establishes a pattern of social stratification. An understanding of the association of social and environmental inequality is thus critical for urban sustainability. Based on the Chinese urban household survey from 2002 to 2009, this article employs the lifestyle approach to calculate and analyse the inequality of households by direct and indirect carbon emissions. The correlations among carbon emission inequality with income and housing wealth inequality are estimated with a Heckman procedure. We find that not only income distribution but also housing wealth distributionis an important consideration in understanding environmental inequality in China. 相似文献
95.
De-Shuang Huang Xing-Ming Zhao Guang-Bin Huang Yiu-Ming Cheung 《Pattern recognition》2006,39(12):2293-2300
The annotation of proteins can be achieved by classifying the protein of interest into a certain known protein family to induce its functional and structural features. This paper presents a new method for classifying protein sequences based upon the hydropathy blocks occurring in protein sequences. First, a fixed-dimensional feature vector is generated for each protein sequence using the frequency of the hydropathy blocks occurring in the sequence. Then, the support vector machine (SVM) classifier is utilized to classify the protein sequences into the known protein families. The experimental results have shown that the proteins belonging to the same family or subfamily can be identified using features generated from the hydropathy blocks. 相似文献
96.
Leong M.-P. Chi-Chiu Cheung Chin-Wang Cheung Wan P.P.M. Leung I.K.H. Yeung W.M.M. Wing-Seung Yuen Chow K.S.K. Kwong-Sak Leung Leong P.H.W. 《Computer》2005,38(10):70-77
The Clustertech parallel environment is an object-oriented C++ library that uses abstractions to simplify parallel programming for financial engineering applications. The message passing interface ensures CPE's portability and performance over a wide range of parallel cluster and symmetric multiprocessing machines. 相似文献
97.
Automatic generation of artistic chinese calligraphy 总被引:1,自引:0,他引:1
Chinese calligraphy is among the finest and most important of all Chinese art forms and an inseparable part of Chinese history. Its delicate aesthetic effects are generally considered to be unique among all calligraphic arts. Its subtle power is integral to traditional Chinese painting. A novel intelligent system uses a constraint-based analogous-reasoning process to automatically generate original Chinese calligraphy that meets visually aesthetic requirements. We propose an intelligent system that can automatically create novel, aesthetically appealing Chinese calligraphy from a few training examples of existing calligraphic styles. To demonstrate the proposed methodology's feasibility, we have implemented a prototype system that automatically generates new Chinese calligraphic art from a small training set. 相似文献
98.
Similarity search is a core module of many data analysis tasks, including search by example, classification, and clustering. For time series data, Dynamic Time Warping (DTW) has been proven a very effective similarity measure, since it minimizes the effects of shifting and distortion in time. However, the quadratic cost of DTW computation to the length of the matched sequences makes its direct application on databases of long time series very expensive. We propose a technique that decomposes the sequences into a number of segments and uses cheap approximations thereof to compute fast lower bounds for their warping distances. We present several, progressively tighter bounds, relying on the existence or not of warping constraints. Finally, we develop an index and a multi-step technique that uses the proposed bounds and performs two levels of filtering to efficiently process similarity queries. A thorough experimental study suggests that our method consistently outperforms state-of-the-art methods for DTW similarity search. 相似文献
99.
As a joint effort between the Chinese Academy of Sciences and the Hong Kong University of Science and Technology, the BLOSSOMS sensor network project aims to identify research issues at all levels from practical applications down to the design of sensor nodes. In this project, a heterogeneous sensor array including different types of application-dependent sensors as well as monitoring sensors and intruding sensors are being developed. Application-dependent power-aware communication protocols are also being studied for communications among sensor nodes. An ontology-based middleware is built to relieve the burden of application developers from collecting, classifying and processing messy sensing contexts. This project is also developing a set of tools allowing researchers to model, simulate/emulate, analyze, and monitor various functions of sensor networks. 相似文献
100.