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91.
变换编码对于电能质量数据压缩的提高是一项很重要的技术。文章首先介绍了离散余弦变换(DCT)的基本概念,然后对电能质量数据进行映射变换,并利用MATLAB进行仿真研究,利用离散余弦变换将原始电能质量数据映射到离散余弦空间,产生了更有效更紧凑的系数,但是直接对采样数据进行DCT处理,压缩比与精度成反比。提出数据复制组合方法进行改进,实验证明此方法有利于熵编码压缩码率和数据精度的提高。 相似文献
92.
XU Ou LU ShaoHua & JIAN ShuiSheng Faculty of Information Engineering Guangdong University of Technology Guangzhou China 《中国科学:信息科学(英文版)》2010,(2):390-397
The polarization properties for tilted fiber Bragg gratings (TFBGs) are investigated theoretically based on coupled-mode theory and Mueller matrix method. The expression of wavelength-related polarizationdependent loss (PDL) for TFBGs with different tilt angles is derived and calculated. Simulation results are compared, and the results indicate that the polarization capability of TFBGs with 45° angle is stronger than other TFBGs with smaller angles. The degree of polarization for unpolarized light passing T... 相似文献
93.
Understanding buyers' loyalty to a C2C platform: the roles of social capital,satisfaction and perceived effectiveness of e‐commerce institutional mechanisms 下载免费PDF全文
Qian Huang Xiayu Chen Carol Xiaojuan Ou Robert M. Davison Zhongsheng Hua 《Information Systems Journal》2017,27(1):91-119
Drawing upon social capital theory, this study aims to investigate how different dimensions of social capital affect online buyers' satisfaction and ultimately boost their loyalty to a Consumer‐to‐Consumer (C2C) platform. Specifically, we propose that three dimensions of social capital (i.e., cognitive, structural and relational capital) contribute positively to the two types of online buyers' satisfaction (i.e., economic and social satisfaction). In addition, we posit that perceived effectiveness of e‐commerce institutional mechanisms (PEEIM) moderates the relationships between economic and social satisfaction and buyers' loyalty to the platform. Three hundred buyers on the Consumer‐to‐Consumer platform, TaoBao, were surveyed to test the proposed model. The results suggest that buyers' evaluation of social capital with the community of sellers can enhance their satisfaction with the sellers, which subsequently affect their loyalty to the platform. Furthermore, perceived effectiveness of e‐commerce institutional mechanisms negatively moderates the effect of economic satisfaction and positively moderates the effect of social satisfaction on buyers' loyalty to the platform. The theoretical contributions and practical implications are discussed. 相似文献
94.
Colorization is a technique to automatically produce color components for monochrome images and videos based on a few input colors. Generally, image colorization is initialized from a number of seed pixels whose colors are specified by users, and then the colors are gradually prorogating to the monochrome surroundings under a given optimization constraint. So, the performance of colorization is highly dependent on the selection of seed pixels. However, little attention has been paid to the selection of seed pixels, and how to improve the effectiveness of manual input remains a challenging task. To address this, an improved colorization method using seed pixel selection is proposed to assist the users in determining which pixels are highly required to be colorized for a high-quality colorized image. Specifically, the gray-scale image is first divided into non-overlapped blocks, and then, for each block, two pixels that approximate the average luminance of block are selected as the seeds. After the seed pixels are colored by users, an optimization that minimizes the difference between the seeds and their adjacent pixels is employed to propagate the colors to the other pixels. The experimental results demonstrate that, for a given amount of inputs, the proposed method can achieve a higher PSNR than the conventional colorization methods. 相似文献
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96.
Abstract Owing to the lack of face-to-face interactions, students using a web-based learning system are likely to study alone and with relatively little classmate support and pressure. Teachers in a web-based learning system may apply a group-learning model to overcome this problem. Teachers first need to organise, manage and monitor the group learning and they must take appropriate actions based on teaching strategies to improve the learning achievements of the students. To perform these tasks effectively, teachers must obtain relevant information by analysing the huge volume of web-access logs or by monitoring web interactions. This paper presents novel methodologies for developing instruments to assist teachers in performing intervention and strategy analysis. The proposed methodologies apply data mining tools provided by existing database management systems. Database techniques, including the multi-dimensional cube, are then applied to make student web logs meaningful and helpful to teachers in managing group learning. The associate rule mining tool is finally employed to assist teachers in analysing their pedagogical strategies. These tools relieve teachers of tedious data collection and analysis, allowing them to focus on managing the groups to promote students' learning achievement. 相似文献
97.
In this paper, a model‐refining method is proposed to alleviate the complexity involved in specification interpretation of DES control problems. The legal constraint language is defined in terms of illegal states and events in contrast with constructing the automaton of the specification language. This method could provide a more intuitive view of the DES control problem and would be suitable for practical implementation. Two examples, which have commonly been used in the literature, are employed to show the efficiency of the proposed method. Further, under this framework, it is shown that the supremal controllable sublanguage can take a simpler form based on the concept of an illegal state set. A state‐based supervisor synthesis procedure is presented, and a simple example is provided. 相似文献
98.
99.
Subei Ou Lianguo Wang Peipei Wang Zhansheng Wang Jihui Huang Donglei Zhou 《矿业科学技术学报(英文版)》2013,23(2):237-244
Based on the importance of fractured rock mass seepage research, in order to analyze seepage flow characteristics of collapse column under the influence of mining, a method by embedding fractured rock mass flow solid coupling relationship into FLAC3D internal flow models is presented according to fluid–solid coupling theory and strength criterion. A calculation model of numerical analysis was established, and the influences of mining pressure and plastic damage to pore water pressure and seepage vector change rule were studied. The results show that collapse column is the main channel of confined water seepage upward. The impact is not big when the workface is away from the collapse column. But when the workface is nearing a collapse column, there will be a seepage channel on a side near the workface, in which seepage vector and head are comparatively large. With workface pushing through collapse column, the seepage channel transfers to the other side of the column. In addition, when the plastic damage area within the collapse column breaks through, a “pipeline flow” will be formed within the column, and seepage field will change remarkably and the possibility of water bursting will be greater. 相似文献
100.
In this research we study the multi-product Economic Lot Scheduling Problem (ELSP) with manufacturing and remanufacturing opportunities. Manufacturing and remanufacturing operations are performed on the same production line. Both manufactured and remanufactured products have the same quality thus they fulfil the same demand stream. Tang and Teunter (2006) firstly studied this type of Economic Lot Scheduling Problem with Returns (ELSPR) and presented a complex algorithm for the optimal solution. More recently Teunter, Tang, and Kaparis (2009) proposed several heuristics to deal with the same problem using more computational efficient approaches. However, both studies have limited the attention to the common cycle policy with the assumption that a single (re)manufacturing lot is used for each item in each cycle. Relaxing the constraint of common cycle time and a single (re)manufacturing lot for each item in each cycle, we propose a simple, easy to implement algorithm, based on Segerstedt (1999), to solve the model using a basic period policy. Several numerical examples show the applicability of the algorithm and the cost savings. 相似文献