Efficient channel code rate selection algorithms for forward error correction of packetized multimedia bitstreams in varying channels

We study joint source-channel coding systems for the transmission of images over varying channels without feedback. We consider the situation where the channel statistics are unknown to the transmitter and focus on systems that enable good performance over a wide range of channel conditions. We first propose a linear-time channel code rate selection algorithm for a hybrid transmission system that combines packetization of an embedded wavelet bitstream into independently decodable packets and forward error correction with a concatenated cyclic redundancy check/rate-compatible punctured convolutional (RCPC) channel coder. We then consider an extension of this hybrid system with additional Reed-Solomon (RS) coding across the packets and give a linear-time algorithm for the efficient selection of both the RS and RCPC code rates. Experimental results for a wireline/wireless link modeled as the combination of a packet erasure channel and a Rayleigh flat-fading channel showed that our schemes significantly outperformed the best previous forward error correction systems in many situations where the actual channel parameter values deviated from the ones used in the optimization of the source-channel rate allocation.     

Power-aware code scheduling assisted with power gating and DVS

Traditionally, code scheduling is used to optimize the performance of an application, because it can rearrange the code to allow the execution of independent instructions in parallel based on instruction level parallelism (ILP). According to our observations, it can also be applied to reduce power dissipation by taking advantage of the properties of existing low-power techniques. In this paper, we present a power-aware code scheduling (PACS), which is a code scheduling integrated with power gating (PG) and dynamic voltage scaling (DVS) to reduce power consumption while executing an application. In other words, from the viewpoint of compilation optimization, PG and DVS can be applied simultaneously to a code and their impact can be enhanced by code scheduling to further save power. The result shows that when compared with hardware power gating, the proposed PACS can outperform by more than 33% and 41% in terms of energy delay product and energy delay² product for DSPStone and Mediabench.     

Countering unauthorized code execution on commodity kernels: A survey of common interfaces allowing kernel code modification

Motivated by the goal of hardening operating system kernels against rootkits and related malware, we survey the common interfaces and methods which can be used to modify (either legitimately or maliciously) the kernel which is run on a commodity desktop computer. We also survey how these interfaces can be restricted or disabled. While we concentrate mainly on Linux, many of the methods for modifying kernel code also exist on other operating systems, some of which are discussed.     

Stabilizing a first order system with an arbitrarily large time varying delay and an uncertain gain

Handling delays and uncertain parameters in control systems is difficult and of long-standing interest. In this paper, we consider the problem of stabilizing (in a bounded-input–bounded-output sense) a first order linear time invariant plant with an arbitrarily large time varying delay and an arbitrarily large uncertain gain; we propose the use of a mildly non-linear, periodic controller, which is simple to implement. We will derive a clear, simple formula relating the maximum delay duration, the location of the unstable plant pole and the bounds on the derivative of the delay for which our controller stabilizes the system.     

Common randomness and distributed control: A counterexample

When agents collaborate to perform a control task, it is of interest to characterize the set of joint probability distributions they can achieve on their joint action space when they are passively provided with external common randomness. We give a simple counterexample to a natural conjecture about this class of joint distributions.     

Uncertain random variables: a mixture of uncertainty and randomness

In many cases, human uncertainty and objective randomness simultaneously appear in a system. In order to describe this phenomena, this paper presents a new concept of uncertain random variable. To measure uncertain random events, this paper also combines probability measure and uncertain measure into a chance measure. Based on the tool of chance measure, the concepts of chance distribution, expected value and variance of uncertain random variable are proposed.     

Robust re-identification using randomness and statistical learning: Quo vadis

The re-identification problem is to match objects across multiple but possibly disjoint fields of view for the purpose of sequential authentication over space and time. Detection and seeding for initialization do not presume known identity and allow for re-identification of objects and/or faces whose identity might remain unknown. Specific functionalities involved in re-identification include clustering and selection, recognition-by-parts, anomaly and change detection, sampling and tracking, fast indexing and search, sensitivity analysis, and their integration for the purpose of identity management. As re-identification processes data streams and involves change detection and on-line adaptation three complementary statistical learning frameworks, driven by randomness for the purpose of robust prediction, are advanced here to support the functionalities listed earlier and their combination thereof. The intertwined learning frameworks employed are those of (a) semi-supervised learning (SSL); (b) transduction; and (c) conformal prediction. The overall architecture proposed is data-driven and modular, on one side, and discriminative and progressive, on the other side. The architecture is built around autonomic computing and W5+. Autonomic computing or self-management provides for closed-loop control. W5+ answers questions related to What data to consider for sampling and collection, When to capture the data and from Where, and How to best process the data. The Who (is) query is about identity for biometrics, and the Why question for explanation purposes. The challenge addressed throughout is that of evidence-based management to progressively collect and add value to data in order to generate knowledge that leads to purposeful and gainful action including active learning for the overall purpose of re-identification. A venue for future research includes adversarial learning when re-identification is possibly “distracted” using deliberate corrupt information.     

A Godunov-type scheme for modelling 1D channel flow with varying width and topography

One-dimensional (1D) numerical models have long been used in simulating fluvial hydrodynamics. While most of these models are based on the solutions to some approximate forms of the fully 1D St. Venant equations, it is desirable to have a 1D code that can deal with those highly dynamic and complex flows under certain flood conditions, with full consideration of the convective and source terms. This paper therefore presents a Godunov-type alternative for solving the 1D inhomogeneous shallow water equations with complex source terms. The model is also implemented with a wetting and drying condition to avoid producing negative water depth. The proposed model is validated by a selection of steady and transient hydraulic problems with reference solutions.     

The classical-quantum multiple access channel with conferencing encoders and with common messages

We prove coding theorems for two scenarios of cooperating encoders for the multiple access channel with two classical inputs and one quantum output. In the first scenario (ccq-MAC with common messages), the two senders each have their private messages, but would also like to transmit common messages. In the second scenario (ccq-MAC with conferencing encoders), each sender has its own set of messages, but they are allowed to use a limited amount of noiseless classical communication among each other prior to encoding their messages. This conferencing protocol may depend on each individual message they intend to send. The two scenarios are related to each other not only in spirit—the existence of near-optimal codes for the ccq-MAC with common messages is used for proving the existence of near-optimal codes for the ccq-MAC with conferencing encoders.     

Periodicity, directionality, and randomness: Wold features forimage modeling and retrieval

One of the fundamental challenges in pattern recognition is choosing a set of features appropriate to a class of problems. In applications such as database retrieval, it is important that image features used in pattern comparison provide good measures of image perceptual similarities. We present an image model with a new set of features that address the challenge of perceptual similarity. The model is based on the 2D Wold decomposition of homogeneous random fields. The three resulting mutually orthogonal subfields have perceptual properties which can be described as “periodicity,” “directionality,” and “randomness,” approximating what are indicated to be the three most important dimensions of human texture perception. The method presented improves upon earlier Wold-based models in its tolerance to a variety of local inhomogeneities which arise in natural textures and its invariance under image transformation such as rotation. An image retrieval algorithm based on the new texture model is presented. Different types of image features are aggregated for similarity comparison by using a Bayesian probabilistic approach. The, effectiveness of the Wold model at retrieving perceptually similar natural textures is demonstrated in comparison to that of two other well-known pattern recognition methods. The Wold model appears to offer a perceptually more satisfying measure of pattern similarity while exceeding the performance of these other methods by traditional pattern recognition criteria. Examples of natural scene Wold texture modeling are also presented     

Software randomness analysis and evaluation of lightweight ciphers: the prospective for IoT security

Multimedia Tools and Applications - In the past few years, various lightweight cryptographic algorithms have been proposed to balance the trade-offs between the requirements of resource constrained...     

Landsat continuity: Issues and opportunities for land cover monitoring

Initiated in 1972, the Landsat program has provided a continuous record of earth observation for 35 years. The assemblage of Landsat spatial, spectral, and temporal resolutions, over a reasonably sized image extent, results in imagery that can be processed to represent land cover over large areas with an amount of spatial detail that is absolutely unique and indispensable for monitoring, management, and scientific activities. Recent technical problems with the two existing Landsat satellites, and delays in the development and launch of a successor, increase the likelihood that a gap in Landsat continuity may occur. In this communication, we identify the key features of the Landsat program that have resulted in the extensive use of Landsat data for large area land cover mapping and monitoring. We then augment this list of key features by examining the data needs of existing large area land cover monitoring programs. Subsequently, we use this list as a basis for reviewing the current constellation of earth observation satellites to identify potential alternative data sources for large area land cover applications. Notions of a virtual constellation of satellites to meet large area land cover mapping and monitoring needs are also presented. Finally, research priorities that would facilitate the integration of these alternative data sources into existing large area land cover monitoring programs are identified. Continuity of the Landsat program and the measurements provided are critical for scientific, environmental, economic, and social purposes. It is difficult to overstate the importance of Landsat; there are no other systems in orbit, or planned for launch in the short-term, that can duplicate or approach replication, of the measurements and information conferred by Landsat. While technical and political options are being pursued, there is no satellite image data stream poised to enter the National Satellite Land Remote Sensing Data Archive should system failures occur to Landsat-5 and -7.     

TestU01 and Practrand: Tools for a randomness evaluation for famous multimedia ciphers

Multimedia Tools and Applications - New dangerous attacks have arisen as we witness the current evolution of digital data. Connecting devices, vehicles, even our own bodies to the Internet have...     

要素细化与代码实现——WSMF模型

Web服务建模框架（WSMF）的实际应用可归结为是在正确理解WSMF本质基础上的要素细化与代码实现。WSMF的本质就是基于“重用性-解耦性-语义中介协调”观点导出的Web服务、目标、中介器、本体4个顶层要素及其相互关系。WSMF的顶层要素及其相互关系由Web服务本体模型（WSMO）细化扩展为层次结构的WSMF底层要素体系。WSMF的底层要素由Web服务建模语言（WSML）做形式化描述,进而转换为XML代码。一个实际的Web服务例证了WSMF顶层要素的细化、形式化、代码化的方法与过程。     

Discreteness versus continuity in information technologies: Quantum calculus and its alternatives

In the paper, we discuss a role of quantum calculus, “differential calculus without taking limits” as a discrete analog of continuous mathematical analysis oriented on information technologies. We studied distinctive calculi that are alternative to quantum calculus and relate finite discriminators of values of an argument with finite discriminators of values of a function at their different combinations.     

Multi-sensor NDVI data continuity: Uncertainties and implications for vegetation monitoring applications

Consistent NDVI time series are paramount in monitoring ecological resources that are being altered by climate and human impacts. An increasing number of natural resource managers use web-based geospatial decision support tools that integrate time series of both historical and current NDVI data derived from multiple sensors to make better informed planning and management decisions. Representative canopy reflectance and NDVI data were simulated for historical, current and future AVHRR, MODIS and VIIRS land surface monitoring satellites to quantify the differences due to sensor-specific characteristics. Cross-sensor NDVI translation equations were developed for surface conditions. The effect of a range of atmospheric conditions (Rayleigh scattering, ozone, aerosol optical thickness, and water vapor content) on the sensor-specific reflectance and NDVI values were evaluated to quantify the uncertainty in the apparent NDVI for each sensor. MODIS and VIIRS NDVI data are minimally affected by the atmospheric water vapor, while AVHRR NDVI data are substantially reduced by water vapor.Although multi-sensor NDVI continuity can be obtained by using the developed cross-sensor translation equations, the interactions between the spectral characteristics of surface vegetation and soil components, sensor-specific spectral band characteristics and atmospheric scattering and absorption windows will introduce uncertainty due to insufficient knowledge about the atmospheric conditions that affect the signal of the Earth's pixels at the time of data acquisitions. Processing strategies and algorithm preferences among data streams are also hindering cross-sensor NDVI continuity.