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Recently, many video-on-demand (VoD) providers store multiple versions of the same videos to offer multiple-quality video services with different bitrates to users, called as multi-version VoD. To decrease the start-up delay for users, it is a good idea to cache videos at caching server that is in close proximity. However, how to decide which versions of which videos should be cached and replaced in caching server is still one major challenge for multi-version VoD systems because of limited caching storage. In this paper, we propose a version-aware video caching strategy for multi-version VoD systems, which aims to reduce start-up delay and improve cache hit ratio. First, we take into account the transcoding delay among versions and transmit delay from content server to caching server to calculate version-aware caching profit when caching a certain version or multiple versions of a video. It is the basis for the following caching replacement algorithm. Second, we propose version-aware video caching (VaVC) algorithm to decide which versions of which videos will be replaced based on the version-aware caching profit dynamically. In this way, VaVC can reduce start-up delay and improve the cache hit ratio. Our simulation results have shown that VaVC outperforms the others in both the start-up delay and the cache hit ratio.

With the continuous development of Healthcare information systems (HIS) [1], malicious and unauthorized access has increased, privacy disclosure issues gradually serious. In order to protect the privacy of HIS, this paper adds context to privacy information access, proposes a new method to realize context constraints, this method rates the context in which the subject is located, determines whether the access is allowed by judging whether the level satisfies the conditions. By adding context constraints to the access, the risk of privacy disclosure is greatly reduced and privacy protection is realized.

The Mg-delta-doping technique was employed in the epitaxial growth of the nonpolar a-plane p-AlGaN films on semi-polar r-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). The structural and electrical properties of the nonpolar a-plane p-AlGaN epi-layers were characterized with secondary ion mass spectroscopy (SIMS), high-resolution X-ray diffraction (HR-XRD), and Hall effect measurement, respectively. The characterization results demonstrated that the crystalline quality, and the efficiency of Mg incorporation in the nonpolar a-plane p-AlGaN films could be improved significantly by optimizing the pulse time of Cp2Mg mass flow in the Mg-delta-doping process. In fact, a hole concentration as high as 1.4×1018 cm−3 under an average Mg incorporation density of ∼1 × 1019 cm−3 was achieved.

The Mg-delta-doping technique was applied for the first time in the epitaxial growth of the non-polar a-plane p-AlGaN films on semi-polar r-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). The structural, morphological and electrical properties of the non-polar α-plane p-AlGaN epi-layers were characterized by high resolution X-ray diffraction (HR-XRD), atomic force microscopy (AFM) and Hall effect measurement, respectively. A maximum carrier concentration of 1.4×1018 cm−3 with an average Mg incorporation of ∼1×1019 cm−3 was achieved, which is twice higher than that of the uniformly Mg-doped sample due to the suppression of self-compensation effect in the Mg-delta-doped epi-layers. The characterization results also show that not only the crystalline quality but also the surface roughness can be improved by the Mg-delta-doping procedure. This phenomenon can be explained in terms of the blocking of the dislocation by the MgN protrusions that were formed during the Mg-delta doping procedure.

An Agent-based Computational Economics Model based on Classical Economics, the ACE-CE model for short, is established through a combined approach of the theoretical method and computational method. This model has successfully conducted several applications in China, which has proven the feasibility of mixed methods for large-scale computation in economics. It also verifies the theoretical rationality of classical economics. In particular, the model can vividly replicate economic processes in reality, demonstrating the existence of the invisible hand, a well-known conjecture by Adam Smith that in a market economy, there is an "invisible hand", acting in a regulatory capacity comprised of general rules. However, these general rules are achieved in a spontaneous fashion through enormous numbers of agents via the regulatory effect of profit orientation. This paper will focus on a typical case of the model to analyze the application effect of the model in large-scale computation for social and economic systems.

In order to narrow the gap between the user's implied concept and the low-level visual features, many region-based retrieval methods have been proposed. This paper describes a RBIR system. The system matches images based on user's requirement with an improved integrated region similarity. To improve the retrieval performance, relevance feedback is introduced

Work along with the property of error diffuse halftoning a multi-scale interpolating pyramid transform on two dimension is constructed with the nonlinear median operator. Having investigated the transform distribution of halftone noise in the approximation and the detail on each-scale, the de-noising method is studied through many experiments, and an inverse halftoning algorithm based on the expanded median-interpolating pyramid transform (EMIPT) is proposed. Firstly the method decomposes halftoning image by the transform in one-scale, and a Wiener filter is applied to the detail coefficient. Then an inverse image is reconstructed from the cleaned detail and the approximation. Experiments show that the proposed transform can separate the halftone noise and the image detail better than linear multi-scale transform. And the inverse halftoning method based on it includes some excellent performances such as smoothing the halftone patterns, efficient edge preserving ability, high PSNR and small memory requirement

Let X be a Banach space and f:X /spl rarr/(-/spl infin/, /spl infin/) be a proper and lower semicontinuous function, denoted as S={x /spl isin/ X:f(x)/spl les/0}, ds(x) :=inf{/spl par/x-s/spl par/:s /spl isin/ S}. We say that the system f(x) /spl les/ 0 (or s) has a local (global) error bound if S is nonempty and, for some 0 < /spl mu/ and /spl epsiv/ /spl isin/(0,+/spl infin/) (/spl epsiv/=+/spl infin/), ds(x) /spl les/ /spl mu/f(x)+/spl forall/x /spl isin/ X with f/sub +/(x)