共查询到20条相似文献，搜索用时 15 毫秒
1.
HU Xin HE Sailing 《浙江大学学报(A卷英文版)》2007,8(8):1179-1182
We propose a new class of negative refractive index transmission line in which ideal operational amplifiers are applied to form the periodically loaded negative-impedance-converted inductors and capacitors. The phase response of the new trans-mission line is opposite to that of a positive refractive index conventional transmission line. Unlike the existing negative refractive index transmission line,the new negative refractive index transmission line is non-dispersive and thus can lead to many novel applications such as designing new broadband devices. 相似文献
2.
Yael Fisher 《美中教育评论》2010,7(6):1-15
This paper reveals a new evaluation model, which enables educational program and project managers to evaluate their programs with a simple and easy to understand approach. The ＂index of success model＂ is comprised of five parameters that enable to focus on and evaluate both the implementation and results of an educational program. The integration of these parameters forms a complete and comprehensive picture, which in turn provides the most information on the success or failure of the program. The parameters are： （1） the relevance index, referring to an evaluation of predefined objectives; （2） the efficiency index, referring to the fiscal efficiency of the program; （3） the effectiveness index evaluating the attainment of the program＇s objectives; （4） the impact index gauging the effect on the consumers, for whom the program is undertaken; and （5） the final parameter is the program＇s sustainability index. Since Israel＇s education strategy currently leans towards site-based monitoring and evaluation, such a model can potentially be of great help to school management and staff. 相似文献
3.
Qi-yin ZHU Ze-xiang WU Yan-ling LI Chang-jie XU Jian-hua WANG Xiao-he XIA 《浙江大学学报(A卷英文版)》2014,15(4):272-281
Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae. 相似文献
4.
The Hong Kong Hang Seng index futures is taken as a study object and a method of empirical analysis is adopted in order to verify the validity of the application of the value-at-risk (VaR) method in the risk measurement of the stock index futures market. The results suggest that under normal market conditions it is feasible to apply the VaR method in the measurement of the market risks of stock index futures. The daily VaR value of the stock index futures provides a foreseeable profit and loss of the stock index futures. Financial supervisors can adjust their supervising strategies according to the daily VaR value. The speculators can adjust risk capital reserve rates in the same way. The application of this method in China's stock index futures market requires the solutions to specific problems: the absence of historical data, the difficult confirmation of non-risk interest rates etc. 相似文献
5.
LIANG Jun-jie FENG Yu-cai 《浙江大学学报(A卷英文版)》2007,8(6):857-863
Various index structures have recently been proposed to facilitate high-dimensional KNN queries, among which the techniques of approximate vector presentation and one-dimensional (1D) transformation can break the curse of dimensionality. Based on the two techniques above, a novel high-dimensional index is proposed, called Bit-code and Distance based index (BD). BD is based on a special partitioning strategy which is optimized for high-dimensional data. By the definitions of bit code and transformation function, a high-dimensional vector can be first approximately represented and then transformed into a 1D vector, the key managed by a B -tree. A new KNN search algorithm is also proposed that exploits the bit code and distance to prune the search space more effectively. Results of extensive experiments using both synthetic and real data demonstrated that BD out- performs the existing index structures for KNN search in high-dimensional spaces. 相似文献
6.
A kind of image distortion in Optical Coherence Tomography (OCT) resulted from average refractive index changes between structures of bio-tissue is discussed for the first time. Analysis is given on following situations:1) Exact refraction index changes between mierostruetures;2)The gradient of average refractive index change between different tissue layers is parallel to the probe beam;3) The gradient of average refractive index change is vertical to the probe beam. The results show that the image distortion of situation 1) is usually negligible ;in situation 2) there is a spread or shrink effect without relative location error; however, in situation 3)there is a significant image error inducing relative location displacement between different structures. Preliminary design to eliminate the distortion is presented, the method of which mainly based on the image classification and pixel array re-arrangement. 相似文献
7.
A customer-classified evaluation system is described with the customization-supporting tree of evaluation indexes, in which users can determine any evaluation index independently. Based on this system, a customer-classified algorithm based on fuzzy clustering analysis is proposed to implement the customer-classified management. A numerical example is presented, which provides correct results,indicating that the algorithm can be used in the decision support system of CRM. 相似文献
8.
An assessment index model was established to evaulate the benefit of the Three-Gorges Reservoir migration through the analytical hierarchy process. Totally 43 indicators were selected to assess the impact of migration on the economic, social and ecological environmental aspects of the migration communities, with the data of the indicators of the years 1992, 1998, 2002 which represented the period of premigration, the end of the first phase migration and the end of the second phase migration, respectively. The evaluation matrix is sufficiently consistent, with a consistency ratio CR equal to 0.086 3. The assessment turned out a benefit value for the economic subsystem in the year 2004 larger than triple the value in the year 1992, indicating a remarkable economic growth in the Reservoir area. The constantly increasing value for the social subsystem reflects the stable social situations. There is a slight decline in the assessment outcome of the ecological subsystem for the year 1998, which implies enviromental conservation was given insufficient importance during that period. On the whole, the implementation of the migration project is favorable to the Reservoir region, as confirmed by the stably increasing overall evaluation value from 42.22% in 1992 to 68.81% in 2002. However, there is still much room to improve from the status quo to the target criteria. 相似文献
9.
A A ride in a cable-car is one of the most exciting and enjoyable experiences a child can have. In Switzerland, which is the home of the cable-car, it is used mostly to take tourists up the slope of a mountain, to a restaurant from which one can have a bird's-eye view of the surrounding country, or to the top of ski-run, from which, in winter, skiers glide down the snow-cov- ered slope on skis, in Singapore, however, the cable-car takes one from the summit of a hill on the main island 相似文献
10.
Non-local means(NLM)method is a state-of-the-art denoising algorithm, which replaces each pixel with a weighted average of all the pixels in the image. However, the huge computational complexity makes it impractical for real applications. Thus, a fast non-local means algorithm based on Krawtchouk moments is proposed to improve the denoising performance and reduce the computing time. Krawtchouk moments of each image patch are calculated and used in the subsequent similarity measure in order to perform a weighted averaging. Instead of computing the Euclidean distance of two image patches, the similarity measure is obtained by low-order Krawtchouk moments, which can reduce a lot of computational complexity. Since Krawtchouk moments can extract local features and have a good antinoise ability, they can classify the useful information out of noise and provide an accurate similarity measure. Detailed experiments demonstrate that the proposed method outperforms the original NLM method and other moment-based methods according to a comprehensive consideration on subjective visual quality, method noise, peak signal to noise ratio(PSNR), structural similarity(SSIM) index and computing time. Most importantly, the proposed method is around 35 times faster than the original NLM method. 相似文献
11.
Massimo GIUSTI Davide ORLANDI Giulia MELLE Barbara MASSA Enzo SILVESTRI Francesco MINUTO Gianni TURTULICI 《Journal of Zhejiang University. Science. B》2013,14(3):195-206
Ultrasonography(US) and the new applications US elastography(USE) and contrast-enhanced US(CEUS) are used in the screening of thyroid nodules,for which fine-needle aspiration biopsy(FNAB) is the best single diagnostic test.The aim of the study was to compare the sensitivity,specificity,positive predictive value(PPV),and accuracy of the four examinations in nodules with cytological and histological diagnoses.The study used data from US,FNAB,USE(elasticity(ELX 2/1) index),and CEUS(Peak index and time to peak(TTP) index) evaluated in 73 thyroid nodules in 63 consecutive patients likely to undergo surgery.Cytological-histological correlation was available for 38 nodules.No correlation emerged between nodule size and cytological results.A significant(P=0.03) positive correlation between cumulative US findings and cytological results was found.In addition,significant correlations between cumulative US findings and cytology(P=0.02) and between cumulative US findings and histology(P<0.0001) were found.US showed the best specificity and PPV,and FNAB the best sensitivity.There was no significant difference in the ELX 2/1 index,Peak index,or TTP index among nodules subdivided according to cytological scores.No significant correlation was found between ELX 2/1 index,Peak index,and TTP index,on the one hand,and nodule size,US cumulative findings,cytology,and histology on the other hand.The sensitivity of the ELX 2/1 index was high,but its specificity was very low.The accuracy and PPV of USE were lower than those of the other procedures.Only the correlation between Peak index and cumulative US findings reached a value close to significance.Our ultimate aim is to minimise unnecessary thyroidectomy.US and FNAB continue to play a central diagnostic role.The use of a US score showed high specificity and PPV.The specificity of FNAB was low in this selected series because of the numbers of indeterminate cytological responses.USE and CEUS are innovative techniques that need to be standardized.The ELX 2/1 index,Peak index,and TTP index seem to be unrelated to histology.The best statistical data on USE and CEUS concerned their sensitivity and PPV,respectively.At present,USE and CEUS are too time-consuming and of limited utility in selecting patients for surgery. 相似文献
12.
Phonetics The study of the speech sounds of a language,either in relation to their physical properties or in relation to the way in which they are produced by the human organs ofspeech. Phonology The study of the way in which sounds areorganised in languages into systems which convey meaning 相似文献
13.
Loneliness is one of the central themes in the works of Nathanial Hawthorne,which,to some extent,is a reflection of Hawthorn’s keen sensitiveness to the existential anxiety of man in his times.The paper explores the theme of alienation that is exposed in the The House of the Seven of Seven Gables by making a careful analysis of morbid mentality of Hepzibah,which is mainly displayed in Hepzibah’s alienated feelings to the outside society and abnormal passion for Clifford. 相似文献
14.
YANG Xiao-hua HUANG Jing-feng WANG Fu-min WANG Xiu-zhen YI Qiu-xiang WANG Yuan 《浙江大学学报(A卷英文版)》2006,7(12):2002-2006
There is increasing interest in using hyperspectral data for quantitative characterization of vegetation in spatial and temporal scopes. Many spectral indices are being developed to improve vegetation sensitivity by minimizing the background influence. The chlorophyll absorption continuum index （CACI） is such a measure to calculate the spectral continuum on which the analyses are based on the area of the troughs spanned by the spectral continuum, However, different values of CACI were obtained in this method because different positions of continuums were determined by different users. Furthermore, the sensitivity of CACI to agronomic parameters such as green leaf chlorophyll density （GLCD） has been reduced because the fixed positions of continuums are determined when the red edge shifted with the change in GLCD. A modified chlorophyll absorption continuum index （MCACI） is presented in this article. The red edge inflection point （REIP） replaces the maximum reflectance point （MRP） in near-infrared （NIR） shoulder on the CACI continuum. This MCACI has been proved to increase the sensitivity and predictive power of GLCD. 相似文献
15.
This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy. 相似文献
16.
This essay discusses the issue concerning the use of literature as a pedagogic tool in the EFL reading classroom, which is different from the traditional study of literature. It aims to illustrate that literary texts can be used as a useful language teaching resource rather than as an object of literary study. In the essay, the first part talks about the values of using literature in the EFL reading classroom. The second part is a set of activities related to a specific literary text which aim to develop some of the values identified in the first part. 相似文献
17.
Yusuf sahin 《美中教育评论》2011,(5):580-588
The aim of this paper is to determine the elements which hinder peace, and emphasize the importance of the contribution of foreign language learning to international peace. Language affects the thought and behavior of human beings. The attitude of a person knowing more than one language of a position is not the same as a person not knowing a foreign language because of that the first person can comment about the position in different standpoints. He can see and evaluate the events in a much broader perspective. As knowledge gives comfort, peace and confidence to the human beings, ignorance causes repulse and revulsion. Knowing a foreign language means entering a world of human beings thinking and believing differently, accepting different life-styles, illuminating, clarifying the obscurities which cause prejudice and revealing human behaviors which seem not comprehensible whereas they are actually very easy to understand. A theory can be developed from all explanations emphasizing the contributions of knowing a foreign language to the international communication. The theory is called ＂push and pull theory in communication＂. The huge building of ignorance, which is the place of big wars and conflicts, can be eliminated through the power of love and peace language. To obtain international peace, all the nations in the world should try to maintain and create legal and social background in order to realize their common goal ＂international peace＂. All the governments should come together and develop a common program which provides a contribution to the improvement of the international peace language, which should be taught as a lesson called ＂common peace language＂ in all countries. Foreign language teaching should be started at the very early stage if possible. The children＇s books must contain differences that are natural but not the things to be ashamed of or things to boast about. With the contributions of all countries, a foundation can be set up so that all successful students and teachers, especia 相似文献
18.
Considering the uncertainty of material performance, geometric characteristic and analysis method, the analysis of statistical parameters of the resistance of cast ball-and-socket support joints and the reliability analysis are carried out by JC method (improved first-order second-moment method) based on the relevant experimental data. Results show that the resistance partial factor of the joint increases with the increase of the reliability index. The resistance partial factors are suggested corresponding to the reliability index under different load combinations. Moreover, the suggested resistance partial factor is adopted in reliability design, and it is found that the reliability index of the joint is larger than the target reliability index. The optimal load combination is the one in which live load plays an important control role. Finally, based on the suggested resistance partial factors, the reliability analysis of cast ball-and-socket support joints of a project is conducted. 相似文献
19.
From the linguistic aspect,lingua franca is a kind of language which is used habitually by people whose mother tongues are different in order to facilitate communication between them.It may be natural or miscellaneous.In this thesis,examples are taken to show the characteristics of the lingua franca used in business trade with a view to summing up the general feature of this kind of language which is bound to be helpful to some extent in one way or another. 相似文献
20.
Eva Kenesei 《美中教育评论》2011,(5):698-710
The start of higher education of primary school teachers in 1959 marks a definitive step in a process. This training has had an effect on all areas. In terms of music training, different periods can be observed which appears during the full strategic change of the training. Professionals, however, have always tried to find the proper place for music which has to be fought for from time to time. Music education has never lost sight of the Kodaly concept in public education. We aim to prepare our students to internalize the abilities necessary to become a successful primary school teacher, keeping in mind the requirements of qualification for the major. In this process, the changes taken place in the Hungarian higher education were determinative. Music education practically has kept its place in general and special primary school teacher training. The major of primary school teacher is a definitive undergraduate course in the teacher training field. Its importance directly shows in public education. One of the crucial points of education should be the formation of values of schoolchildren. General education is a cultural level different in every society and age that a society sets as a standard for its members. This education itself should have a European culture as a prerequisite with Hungarian characteristics. 相似文献