841469
Variable temporal-length 3-D discrete cosine transform coding
Three-dimensional discrete cosine transform (3-D DCT) coding has the advantage of reducing the interframe redundancy among a number of consecutive frames, while the motion compensation technique can only reduce the redundancy of at most two frames. However, the performance of the 3-D DCT coding will be degraded for complex scenes with a greater amount of motion. This paper presents a 3-D DCT coding with a variable temporal length that is determined by the scene change detector. Our idea is to let the motion activity in each block be very low, while the efficiency of the 3-D DCT coding could be increased. Experimental results show that this technique is indeed very efficient. The present approach has substantial improvement over the conventional fixed-length 3-D DCT coding and is also better than that of the Moving Picture Expert Group (MPEG) coding.
17360670
Priority search technique for MPEG-4 motion estimation of arbitrarily shaped video object
One of the main differences between MPEG-4 and previously standardized video coding schemes is the support of arbitrarily shaped video objects, for which most of the existing fast motion estimation algorithms are not suitable. The conventional fast motion estimation algorithm works well for opaque macroblocks, but not in the case of a boundary macroblock which contains a large number of local minima on its error surface. We propose a fast search algorithm which incorporates the binary alpha-plane to predict accurately the motion vectors of boundary macroblocks. Besides, these accurate motion vectors can be used to develop a novel priority search algorithm which is an efficient search strategy for the remaining opaque macroblocks. Experimental results show that, compared to the conventional methods, our approach requires a low computational complexity and provides a significant improvement in terms of accuracy in motion-compensated video object planes.
6180081
New adaptive partial distortion search using clustered pixel matching error characteristic
The partial distortion search is a particularly attractive fast block-matching algorithm, because it introduces no prediction error as compared with the full-search algorithm. It reduces the number of necessary matching evaluations for every searching point to save computation. In the literature, many researches have tried to improve block-matching algorithms by making use of an assumption that pixels with larger gradient magnitudes have larger matching errors on average. Based on a simple analysis, we have found that on average, pixel matching errors with similar magnitudes tend to appear in clusters for natural video sequences. By using this clustering characteristic, we propose an adaptive partial distortion search algorithm which significantly improves the computational efficiency of the original PDS. This approach is much better than other pixel gradient based adaptive PDS algorithms. In addition, our proposed algorithm is suitable for motion estimation of both opaque and boundary macroblocks of an arbitrary shaped object in MPEG-4 coding.
3198744
Dynamic frame skipping for high-performance transcoding
Transcoding is a process of converting a previously compressed video bitstream into a lower bit-rate bitstream. When some incoming frames are dropped for the frame-rate conversion in transcoding, the newly quantized DCT coefficients of prediction error need to be re-computed, which can create an undesirable complexity as well as introduce re-encoding error. We propose a new architecture for a frame-skipping transcoder to improve picture quality and to reduce complexity. It is observed that re-encoding error is reduced significantly when the strategy of direct summation of DCT coefficients and the error compensation feedback loop are employed. Furthermore, we propose a frame-rate control scheme which can dynamically adjust the number of skipped frames according to the incoming motion vectors and the re-encoding error due to transcoding such that the decoded sequence can have smooth motion as well as better transcoded pictures. Experimental results show that, as compared to the conventional transcoder, the new frame-skipping transcoder is more robust, produces smaller requantization errors, and has simple computational complexity.
10358457
A new adaptive interframe transform coding using directional classification
Interframe transform coding is affected not only by the statistics of spatial details within a frame, but also by the variation of the amount of movement and other temporal activities in different regions of the image sequence. Therefore, adaptive techniques have to be used in order to achieve good image quality. In this paper, we propose a new version of the adaptive interframe coding method, namely directional classification, which is based on image sequence statistics. Blocks with different perceptual features such as edges and high motion activity are categorised to different classes. Then, a new adaptive quantization, associated with appropriate scanning and Huffman coding, are employed based on the classification map. Coding tests using computer simulation show this technique is indeed very efficient.<<ETX>>
9759416
Mobile learning: a new paradigm in electronic learning
As mobile phones become popular, with many people being able to afford them, the demand for mobility is extended to teaching and learning purposes. One recent and significant change in learning environments is the demand for mobility. We introduce a proposed framework of mobile learning. It consists of four functional levels: (1) mobile learning applications, (2) mobile user infrastructure, (3) mobile protocol and (4) mobile network infrastructure. The framework can simplify the design and development so that different parties (e.g. vendors, service providers, designers, developers) can address individual levels. A single party can build on functionalities provided by others. The functions of these four levels are described with some examples. Moreover, practical knowledge management and learning community are two major issues in mobile learning.
894881
Performance improvement of TCP Vegas over heterogeneous networks
Current IP network has become the dominant paradigm for all networking environments. The significant cause of packet losses in such heterogenous networks is no longer limited to network congestion. Traditional TCP interprets every packet loss as caused by congestion which may be not the case in the current Internet. Misinterpretation of wireless random loss as an indication of network congestion results in TCP slowing down its sending rate unnecessarily. We propose a new variant of TCP Vegas named RedVegas. By using the innate nature of Vegas and congestion indications marked by routers, RedVegas may detect random packet losses precisely. Through the packet loss differentiation, RedVegas reacts appropriately to the losses, and therefore the throughput of connection over heterogeneous networks can be significantly improved.
18442431
Understanding the Balanced Effects of Belief and Feeling on Information Systems Continuance
There are innumerable studies on technology adoption as well as continuance of usage. A review of previous research shows that cognitive factors are considered prominently in information technology adoption and continuance while the affective feelings of users are not. Although attitude and user satisfaction are common factors considered in information systems research, these factors only involve partial aspects of feelings. Researchers in the marketing areas, as well as the psychology area, begin to note the importance of feelings in understanding and predicting human and customer behavior. In many modern applications, such as mobile Internet services, user feelings are expected to be important, since users are not just technology users but also service consumers. Drawing upon the support of consumer research, social psychology, and computer science, this study proposes a balanced belief–feeling model of IS continuance. In the process of developing this model, the concepts of attitude, belief, and feelings are further articulated, defined, and distinguished. The balanced model is tested in a survey of mobile Internet users. The results established the validity of the model. A comparison with the IS continuance model shows that the new model can explain significantly more variance in continuance intention, taking into account that the new model has more factors. We offer theoretical reasoning for the balanced effects of belief and feeling on IS continuance and discuss the theoretical and practical implications of this study.
18724966
An Aided Congestion Avoidance Mechanism for TCP Vegas
TCP Vegas detects network congestion in the early stage and successfully prevents periodic packet loss that usually occurs in TCP Reno. It has been demonstrated that TCP Vegas achieves much higher performance than TCP Reno in many aspects. However, TCP Vegas cannot prevent unnecessary throughput degradation when congestion occurs in the backward path, it passes through multiple congested links, or it reroutes through a path with longer round-trip time (RTT). In this paper, we propose an aided congestion avoidance mechanism for TCP Vegas, called Aid-Vegas, which uses the relative one-way delay of each packet along the forward path to distinguish whether congestion occurs or not. Through the results of simulation, we demonstrate that Aid-Vegas can solve the problems of rerouting and backward congestion, enhance the fairness among the competitive connections, and improve the throughput when multiple congested links are encountered.
11665411
Investigating Information Systems Strategic Alignment
Although strategic alignment is an important theoretical concept, and achieving alignment or fit among organizational elements would seem to be an important business objective, empirical demonstrations of the importance of alignment have been uncommon (White 1986). This study attempted to provide an empirical assessment of the nature and importance of information systems strategic alignlnent There is much discussion today about the importance of 1. THE CONCEPTUAL MODEL strategic alignment in general (e.g., Venkatraman and Camillus 1984; White 1986) and information systems (IS) The conceptual model underlying the study is depicted in strategic alignment in particular (e.g., Elam et al. 1988; Figure 1. It depicts the propositions that IS.strategic Henderson and Thomas 1992; Henderson and Venkatraman 1992; Keen 1991; Ward, Griffiths and Whitmore 1990). alignment, defined as the fit existing between business The discussion generally suggests that the better the alignstrategy and IS strategy, impacts performance at the IS ment, the better the expected company performance. level and at the overall business level. However, there have been few empirical verifications of this proposition (White 1986). In addition, the discussion The results of the overall study, and detailed descriptions of about alignment has tended to be imprecise and vague (Van the instruments used to measure business strategy, IS de Ven and Drazin 1985). Important objectives of this strategy, IS effectiveness and business performance, have study were to identify a useful, precise model for the IS been described in Chan et al. (1993) and Chan and Huff strategic alignment construct and to examine empirically (1992) respectively. (Table 1 provides a brief outline of relationships among IS strategic alignment; IS effectiveness, the overall study.) This paper discusses the derivation and and business performance. significance of the IS strategic alignment computations and The discussion opens with a brief overview of the concepthe study's findings regarding alignment tual model underlying this study. Next, instruments that measure business strategy and IS strategy are introduced. Then instruments that measure IS effectiveness and business performance are outlined. This is followed by a 2. MEASURING BUSINESS STRATEGY AND general discussion of various approaches that are used to INFORMATION SYSTEMS STRATEGY assess alignment. Specific models of alignment are evaluated and the primary model for IS strategic alignment used within this research is selected and described. The links In order to assess IS strategic alignment, there needed to be between IS strategic alignment and performance are then assessments of both business strategy and IS strategy. discussed. Finally, the paper concludes with a description Table 2 lists the dimensions of these constructs as operaof the study's implications for management and future tionalized in this study. Multiple indicators were used to research. measure each dimension.