We present an adaptive video transmission scheme for use in a code-division multiple-access network, which incorporates efficient bandwidth allocation among source coding, channel coding, and spreading under a fixed total bandwidth constraint. We derive the statistics of the received signal, as well as a theoretical bound on the packet drop rate at the receiver. Based on these results, a bandwidth allocation algorithm is proposed at the packet level, which incorporates the effects of both the changing channel conditions and the dynamics of the source content. Detailed simulations are done to evaluate the performance of the system, and the sensitivity of the system to estimation error is presented. 相似文献
This study examines the extent to which variations in consumers' sensory assessments of food arise from the inability to report accurately sensory perceptions, from confusion regarding the criteria by which to assess samples, or from differences in their oral breakdown of the products.
Twenty consumers assessed the tenderness of a range of 8 hot, freshly roasted meat samples using Time Intensity (TI). Overall a significant correlation was found between the maximum recorded intensity (Imax) of their TI curves and single sensory scores given by a trained panel. Correlation was significant for only 42% of the consumers individually. Significant correlations were found between the amount of masticatory muscle activity undertaken during chewing (measured using electromyography) and Imax for all but 2 of the consumers. Thus subjects' perceptions were accurately described by their chewing work, suggesting between subject differences in perception arose from differences in the way chewing work was applied to break down the samples. The sensory input from the masticatory muscles may represent the major determinant of perceived tenderness of meat. 相似文献
With the advent of Next Generation Network (NGN), services that are currently provided by multiple specific network-centric
architectures. NGN provides AAA (Anytime, Anywhere and Always on) access to users from different service providers with consistent
and ubiquitous provision of services as necessary. This special issue of NGN includes pervasive, grid, and peer-to-peer computing
to provide computing and communication services at anytime and anywhere. In fact, the application of NGN includes digital
image processing, multimedia systems/services, and so on. Here we focus on the digital image processing technology in NGN
environments. Low-contrast structure and heavy noise in NGN environments can be found in many kinds of digital images, which
makes the images vague and uncertainly, especially in x-ray images. As result, some useful tiny characteristic are weakened—which
are difficult to distinguish even by naked eyes. Based on the combination of no-linear grad-contrast operator and multi-resolution
wavelet analysis, a kind of image enhancement processing algorithm for useful tiny characters is presented. The algorithm
can enhance the tiny characters while confine amplifying noise. The analysis of the results shows that local regions of the
image are enhanced by using the concept of the grad contrast to make image clearer adaptively. Experiments were conducted
on real pictures, and the results show that the algorithm is flexible and convenient. 相似文献
Data on adolescents' after-school experiences and their susceptibility to peer pressure were derived from surveys administered to a heterogeneous sample of 865 adolescents in Grades 5–9. Consistent with the findings of previous studies, the results show that Ss who reported home after school were not significantly different from those who were supervised by their parents at home during after-school hours. However, when a 2nd sample of latchkey children (n?=?594) was studied to include greater variation in after-school experiences, Ss who were more removed from adult supervision were found to be more susceptible to peer pressure to engage in antisocial activity. Ss who were home alone were less susceptible to peer pressure than are those who were at a friend's house after school, and those who were at a friend's house, in turn, were less susceptible than were those who describe themselves as "hanging out." Moreover, latchkey Ss whose parents knew their whereabouts and those who had been raised authoritatively were less susceptible to peer influence than were their peers, even if their afternoons were spent in contexts in which adult supervision was lax and susceptibility to peer pressure was generally high. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
Refined palm olein was dry fractionated via three different cooling programs on laboratory-scale fractionation equipment.
The enrichment and depletion of the main triacylglycerols in the liquid and solid phase was plotted as a function of the crystallization
degree of the oil. It was shown that for the given conditions and palm olein composition, the initial crystals mainly consisted
of PPP, diacylglycerols, POP and PLP. At higher crystallization degrees, a sharp viscosity increase in the crystal suspension
was primarily related to an obvious decrease of POP but also of POS in the recovered superolein, while the general crystallization
rate of the system remained unchanged. Rather than a change in crystallization rate of POP, a change in the ratio between
the crystallizing monounsaturated triacylglycerols is linked with the high viscosity of the crystal slurry. For a comparable
degree of crystallization, the superolein of the more viscous crystal slurry, obtained through a membrane press filtration
up to 15 bar, was more unsaturated than the superolein filtered from the less viscous slurry. Consequently, the high unsaturation
in the corresponding soft palm mid fraction is only the result of an incomplete phase separation, and not due to an increased
intersolubility of unsaturated triacylglycerols in the crystals. 相似文献
Paf is a phospholipid mediator present in human skin which induces inflammatory events such as neutrophil infiltration and
increased vascular permeability. Recent data suggest that cutaneous cells, such as fibroblasts and keratinocytes, produce
paf and that paf is released during allergic cutaneous reactions. It is tempting to speculate that paf may contribute to the
development of various skin disorders with acute and chronic skin inflammation. Paf antagonists may help in bringing answers
to this hypothesis and may offer new prospects for the treatment of cutaneous inflammatory diseases.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, Tokyo, Japan, May 1989. 相似文献
This paper studies parallel training of an improved neural network for text categorization. With the explosive growth on the amount of digital information available on the Internet, text categorization problem has become more and more important, especially when millions of mobile devices are now connecting to the Internet. Improved back-propagation neural network (IBPNN) is an efficient approach for classification problems which overcomes the limitations of traditional BPNN. In this paper, we utilize parallel computing to speedup the neural network training process of IBPNN. The parallel IBNPP algorithm for text categorization is implemented on a Sun Cluster with 34 nodes (processors). The communication time and speedup for the parallel IBPNN versus various number of nodes are studied. Experiments are conducted on various data sets and the results show that the parallel IBPNN together with SVD technique achieves fast computational speed and high text categorization correctness. 相似文献
The miscibility of poly(methylmethacrylate) (PMMA) and (trifluoroethyl methacrylic ester-MMA) copolymers (MMA-MATRIFE) with poly(vinylidene fluoride) (PVDF) and VDF copolymers was studied by differential scanning calorimetry (DSC) as a function of the fluorinated copolymer crystallinity and fluoroalkyl methacrylic ester content in the methacrylic copolymer. Miscibility limits were found identical whatever be the blend preparation technique, although solution mixing induced some polymer fractionation, thus giving slightly higher blend glass transition temperature. The miscibility domain widths are reduced when using MMA-MATRIFE copolymers as compared to PMMA-containing blends and miscibility limits are dependent on the MATRIFE content in the methacrylic copolymer. Moreover, PVDF or VDF copolymer melting enthalpy decrease is associated to a partial dissolution of the semi-crystalline polymer in PMMA or MMA-MATRIFE copolymer above the total miscibility limit. The evolution of dynamic moduli as a function of blends composition confirms the miscibility limits determined by DSC. The Flory-Huggins interaction parameters were determined through the melting point depression analysis and compared to correlate the intensity of inter- or intra-molecular interactions between the polymers to the postulated ‘acidity’ of hydrogen atoms in various VDF-containing polymers. The interaction parameter χ12 increases with the fluoroalkyl methacrylic ester content, corresponding to a prevalence of intra-molecular on inter-molecular interactions in these blends. Similarly, PVDF offers higher χ12 values as compared to VDF-TFE or particularly to VDF-TrFE copolymers. These results highlight the importance of the nature of fluorinated polymers and of the inter- or intra-molecular character of dipolar interactions on both, copolymer miscibility and interaction parameter values. 相似文献
This study presents a narrative synthesis of a systematic literature review relating to multi-agency interoperability and major incident decision-making in high risk, high stake environments. The review methodology includes the identification of relevant studies, a critical appraisal of the concepts inherent in the main review question and a narrative synthesis of the central themes that relate to the study as a whole. The review firstly outlines what, currently, appear to be the perceived defining features of successful interoperability by using the SAFE-T phase model of major incident decision-making. It then considers whether these defining features are realistically achievable in major incident practice. Findings suggest that the current definition of an interoperable network is too demanding for the inherent complexity and dynamic nature of the major incident task environment. Individual teams tend to focus on agency-specific behaviour, as opposed to coordinated multi-team functioning, and so collective interoperability is not achieved. Inevitably, this reduces the ability to perform collaborative behaviours, including decision-making and action implementation. The paper concludes that aiming for the current conceptualisation of interoperability along a hierarchical command structure may actually inhibit effective decision-making. Instead, multi-agency systems would do better to work towards an improved understanding of a non-hierarchical and decentralised yet interoperable major incident management network. Recommendations include the need to relate theory and practice in the development of multi-agency decision-making via simulation-based training and to deepen our understanding of interoperability to prevent inertia in high risk, high stake major incident environments. 相似文献