On Transcoding a B-Frame to a P-Frame in the Compressed Domain

Only a limited number of methods have been proposed to realize heterogeneous transcoding, for example from MPEG-2 to H.263, or from H.264 to H.263. The major difficulties of transcoding a B-picture to a P-picture are that the incoming discrete cosine transform (DCT) coefficients of the B-frame are prediction errors arising from both forward and backward predictions, whilst the prediction errors in the DCT domain arising from the prediction using the previous frame alone are not available. The required new prediction errors need to be re-estimated in the pixel domain. This process involves highly complex computation and introduces re-encoding errors. We propose a new approach to convert a B-picture into a P-picture by making use of some properties of motion compensation in the DCT domain and the direct addition of DCT coefficients. We derive a set of equations and formulate the problem of how to obtain the DCT coefficients. One difficulty is that the last P-frame inside a GOP with an IBBP structure, for example, needs to be transcoded to become the last P-frame in the IPPP structure, and it has to be linked to the previous reconstructed P-frame instead of to the I-frame. We increased the speed of the transcoding process by making use of the motion activity which is expressed in terms of the correlation between pictures. The whole transcoding process is done in the transform domain, hence re-encoding errors are completely avoided. Results from our experimental work show that the proposed video transcoder not only achieves a speed-up of two to six times that of the conventional video transcoder, but it also substantially improves the quality of the video.     

Stage of change in self-management of chronic diseases: Psychometric properties of the Chinese version of the University of Rhode Island Change Assessment (C-URICA) Scale.

Objective: The University of Rhode Island Change Assessment (URICA) Scale has been widely used to assess the readiness to change with regard to various health-related behaviors. The present study aimed to develop a Chinese version of the URICA (C-URICA) for measuring the readiness to change of Chinese participants with chronic diseases. Participants: A group of participants (N=101; 87 women and 14 men) in a chronic disease self-management program were asked to complete the C-URICA. Method: The C-URICA was conducted at the baseline, middle, and end of the 6-week program. Changes in self-management behaviors were also measured. Results: Factor analyses revealed a moderate item-to-subscale fit, indicating that structural validity was retained. Item analyses suggested a moderate item quality. The C-URICA subscales can differentially and effectively predict participants' gains in self-management behaviors at the completion of the intervention program. Conclusion: The C-URICA is suitable for use among Chinese patients with chronic diseases. Further studies should explore the generalizability of the results to different diagnostic groups and subgroups among Chinese populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extended analysis of motion-compensated frame difference for block-based motion prediction error.

In the past, most design and optimization work on hybrid video codecs relied mainly on experimental evidence. A proper theoretical model is always desirable, since this allows us to explain the phenomena of existing codecs and to design better ones. In this paper, we make use of the first-order Markov model to derive an approximated separable autocorrelation model for the block-based motion compensation frame difference (MCFD) signal. A major assumption of our derivation is that the net deformation of pixels is directional, in general, rather than a uniform error distribution in a block. We have also shown that the imperfect block-based motion compensation is significant to the theoretical study and the behavior of motion-compensated codecs. Results of our experimental work show that the derived model can describe the statistical characteristics of the MCFD signals accurately. The model also shows that the imperfectly formulated block-based motion compensation can result in an incorrect MCFD autocorrelation function while, conversely, it can form a better block-based motion compensation scheme.     

An argumentation-oriented multi-agent system for automating the freight planning process

This paper advocates the use of multi-agent systems in the freight forwarding industry. We propose an intelligent mobile agent system to cope with a dynamic freight forwarding environment where up-to-date information is crucial but time-consuming to obtain. A key component of our system is an agent argumentation mechanism that allows decision support agents to discuss, argue, and come to a compromise in order to derive well-explained freight planning solutions. A number of artificial intelligence mechanisms are implemented, namely: (1) a mobile-agent-based automated information gathering mechanism, where designated mobile agents access various websites automatically to gather information (e.g., weather conditions on a candidate route) critical for cargo consolidation and route planning, (2) a fuzzy logics engine for risk evaluation, and (3) a simulated annealing engine for optimizing cargo consolidation. A system prototype is developed and the feasibility of our approach is demonstrated in a case study. A series of experiments are also conducted to evaluate the system’s performance.     

Environmental quality and its changes,an analysis using NDVI

Normalized difference vegetation index (NDVI) derived from SPOT HRV multispectral data was used to study the changing environmental quality of Hong Kong from 1987, 1991 and 1993 to 1995. Conventional change detection techniques such as image differencing or principal components analysis helped to highlight salient changes. These techniques, however, were less effective in identifying subtle changes, in particular the amount and quality of green space. Integrating the mean NDVI values at the Tertiary Planning Unit (TPU) level with census and land-cover data showed that the NDVI values were related to woodland, tall scrubland and high-density urban areas. It was also related to the level of crowding as depicted from a factor analysis of census data. Tracing the changing pattern of mean NDVI values revealed that areas with continuous increases in NDVI values are scattered around old urban districts experiencing improved landscaping. Areas of continuous decrease in NDVI values covered a large part of rural New Territories and western Hong Kong Island revealing the urban expansion process. This provided valuable information for the assessment of environmental quality for planning and management of the environment.     

Preparation of Porous Tin Oxide Nanobelts Using the Electrospinning Technique

The electrospinning method is adopted to prepare utralong PEO/stannic hydroxide composite nanofibers. Tin-oxide nanobelts can be obtained by calcination of the composite nanofibers in an open atmosphere. The nanobelts were characterized by a field emission scanning electron microscope, X-ray diffraction, a transmission electron microscope, a Raman spectromicroscope, and Fourier transform infrared spectroscopy. Microstructural analysis has shown that the nanobelts prepared consist of a continuous network of interconnected SnO₂ grains. As a result, the SnO₂ nanobelts possess a high surface area and continuous porosity, which may be applied for the fabrication of sensitive gas sensors.     

Flexural properties of sawdust reinforced phenolic composites: Pilot study

The advantageous properties of sawdust and phenolic resins were combined by making sawdust reinforced phenolic composites with different percentages by weight of sawdust. The sawdust was divided into three grades in accordance with its particulate size. Garamite and propylene glycol were added individually and together to enhance the flexural properties of the composites obtained. Without any garamite and propylene glycol, it was discovered that the best flexural properties of the composites were obtained when the percentage by weight of sawdust (<300 μm) is up to 15%. Beyond this, the flexural properties dropped significantly; in addition, the fluidity of the composite was very low and the mixture was not suitable for casting. In general, the flexural modulus of the composites decreases with an increase in sawdust content, i.e., they are more elastic but their maximum flexural strain does not improve. Garamite was therefore added to improve the maximum flexural strains of the composites and this was successful. The addition of propylene glycol makes the composite more plastic. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Single-switch electronic ballast with near-unity power factor andsoft-switching characteristic

The design and analysis of a single-switch electronic ballast with near-unity power factor and soft-switching characteristic are presented. The ballast circuit is simple and has a small component count. The experimental results for an 80 W ballast show that it has a power factor higher than 0.99 and a total harmonic distortion of 12%. The operating frequency is between 20-40 kHz. The output power is adjustable and the circuit is reliable     

Image restoration by regularisation in uncorrelated transformdomain

Conventional spatially adaptive regularised image restoration schemes weight the amount of regularisation according to the spatial content of an image. The authors first separately decorrelate the signals under analysis into uncorrelated components and then weight the amount of regularisation performed to these components accordingly. The proposed approach works better than conventional schemes, especially in edge regions     

Significance tests and deduction: Reply to Folger (1989).

Shows that agreeing with R. Folger's (1989) methodological observations does not mean that it is incorrect to use significance tests. This contention is based on the dynamics of theory corroboration, with reference to which the following distinctions are illustrated, namely, the distinctions between (a) statistical hypothesis testing, theory corroboration, and syllogistic argument, (b) a responsible experimenter and a cynical experimenter, (c) logical validity and methodological correctness, and (d) warranted assertability and truth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)