Video Compression - From Concepts to the H.264/AVC Standard

Over the last one and a half decades, digital video compression technologies have become an integral part of the way we create, communicate, and consume visual information. In this paper, techniques for video compression are reviewed, starting from basic concepts. The rate-distortion performance of modern video compression schemes is the result of an interaction between motion representation techniques, intra-picture prediction techniques, waveform coding of differences, and waveform coding of various refreshed regions. The paper starts with an explanation of the basic concepts of video codec design and then explains how these various features have been integrated into international standards, up to and including the most recent such standard, known as H.264/AVC.     

Aero-Acoustics of Modern Transonic Fans—— Fan Noise Reduction from Its Sources

The noise of aerodynamics nature from modern transonic fan is examined from its sources with the perspective of noise reduction through aero-acoustics design using advanced Computational Fluid Dynamics (CFD) tools. In particular the problems associated with the forward propagating noise in the front is addressed. It is identified that the shock wave spillage from the leading edge near the fan tip is the main source of the tone noise. Two different approaches have been studied to reduce the forward arc tone noise and two state-of-art transonic fans are designed using the strategies developed. The following rig tests show that while the fans exhibit other noise problems, the primary goals of noise reduction have been achieved through both fans and the novel noise reduction concept vindicated.     

Development of the bi-directional ultrasound system for base of tongue imaging

The use of conventional ultrasound systems to image the upper airway has been limited because ultrasound energy is attenuated by the air column. In an attempt to study upper airway geometry, we developed a computer controlled bi-directional ultrasound system which combines two conventional ultrasound devices with computer image processing to yield images of upper airway structures. Human studies and cadaver studies were performed to evaluate the system. Images acquired by the bi-directional ultrasound system were comparable to images from 3D volume rendered CT scans. This system may provide valuable data in the study of upper airway physiology and pathology.     

SARs are cis DNA elements of chromosome dynamics: synthesis of a SAR repressor protein

SARs are candidate DNA elements for defining the bases of chromatin loops and possibly for serving as cis elements of chromosome dynamics. SARs contain numerous A tracts, whose altered DNA structure is recognized by cooperatively interacting proteins such as topoisomerase II. We constructed multi-AT hook (MATH) proteins and demonstrate that they specifically bind the clustered A tracts of SARs in chromatin and chromosomes. They are also potent inhibitors of chromosome assembly in mitotic Xenopus extracts, demonstrating the importance of SARs in this process. Titration of SARs with MATH20 (20 hooks) blocks shape determination of chromatids but not chromatin condensation per se. SARs are also required for shape maintenance of chromosomes. If MATH20 is added after formation of chromatids, they collapse and are reshaped by an active, mitotic process into spherical chromatid balls.     

Chloroquine, quinine and quinidine inhibit calcium release from macrophage intracellular stores by blocking inositol 1,4,5-trisphosphate binding to its receptor

Endocrine and exocrine pancreatic morphogenesis is known to occur from ductal epithelium, but the factors that regulate this process are unknown. Vascular endothelial growth factor (VEGF)/vascular permeability factor has recently been reported to affect fetal islet ontogenesis. VEGF is an angiogenic factor with a growth-promoting effect that is thought to be restricted to vascular endothelial cells. We demonstrated that VEGF is also a mitogen for adult rat pancreatic duct epithelial cells in primary culture. VEGF supplementation to a serum-free culture medium increased the 5-bromo-2'-deoxyuridine-pulse labeling index of ductal cells more than 2-fold. Immunohistochemical staining and protein blots revealed that pancreatic duct cells express fetal liver kinase-1 high-affinity receptors for VEGF. In pancreatic tissue, immunohistochemistry shows that VEGF peptide is expressed in normal pancreatic islet cells. In duct ligation-induced acute pancreatitis, numerous inflammatory leukocytes containing VEGF were seen to infiltrate between hyperplastic ducts. In the latter model, islet neogenesis has previously been observed. Our data indicate the possibility that VEGF plays a role in the paracrine regulation of ductal growth and differentiation in vivo, eg, in pancreatitis. In vitro, however, VEGF did not induce endocrine differentiation of ductal cells, indicating that it is not the only factor required for the activation of islet neogenesis.     

Simulations for parallel processing of ultrasound reflection-mode tomography with applications to two-phase flow measurement

An evaluation of the application of a parallel-processing array to the measurement of two-phase flow, such as bubbly oil flow through a pipe, in real-time is described. Pulse-echo ultrasound tomography is used to generate a cross-sectional image of the flow that forms the basis for the deduction of flow parameters, such as the void fraction. The tomographic algorithm used is backprojection adapted for execution on an array of parallel-processing devices. It is shown that real-time reconstruction is feasible using the concepts of parallel processing. Different sensor arrangements were investigated by computer simulation. It is shown that a special multisegment sensor results in a significant improvement in signal-to-noise ratio and image quality and that the reconstructed image benefits from the concurrent activation of multiple receivers per transmitted pulse. The findings may also be useful for nondestructive testing and medical applications.     

正确表面预处理对涂料干膜杀菌剂抗微生物活性的影响

通过使用墙体杀菌清洁与非杀菌清洁后涂料干膜的性能比较，评价了杀菌清洗对提高涂料干膜性能的有效性，揭示了怎样用杀菌清洁提高杀菌系统的特性。同时，比较了传统杀菌剂和新式杀菌剂的性能差别。     

Complexity results on labeled shortest path problems from wireless routing metrics

Metrics to assess the cost of paths through networks are critical to ensuring the efficiency of network routing. This is particularly true in multi-radio multi-hop wireless networks. Effective metrics for these networks must measure the cost of a wireless path based not only on traditional measures such as throughput, but also on the distribution of wireless channels used. In this paper, we argue that routing metrics over such networks may be viewed as a class of existing shortest path problems, the formal language constrained path problems.On this basis, we describe labeled path problems corresponding to two multi-radio wireless routing metrics: Weighted Cumulative Expected Transmission Time (WCETT), developed by Draves et al., and Metric for Interference and Channel-switch (MIC), developed by Yang et al. For the first, we give a concise proof that calculating shortest WCETT paths is strongly NP-Complete for a variety of graph classes. We also show that the existing heuristic given by Draves et al. is an approximator. For the second, we show that calculating loop-free (simple) shortest MIC paths is NP-Complete, and additionally show that the optimization version of the problem is NPO PB-Complete. This result implies that shortest simple MIC paths are only poorly approximable in the worst case.Furthermore, we demonstrate how the polynomial-time algorithm for shortest MIC paths is derivable from an existing language constrained shortest path algorithm. We use this as a basis to exhibit the general utility of viewing multi-channel wireless routing metrics as labeled graph problems, and discuss how a class of related polynomial-time computable metrics are derivable from this algorithm.     

Stability of linear discrete switched systems with delays based on average dwell time method

This paper deals with the problem of exponential stability for a class of linear discrete switched systems with constant delays.The switched systems consist of stable and unstable subsystems.Based on the average dwell time method, some switching signals will be found to guarantee exponential stability of these systems.The explicit state decay estimation is also given in the form of the solutions of linear matrix inequalities(LMIs).An example relating to networked control systems(NCSs) illustrates the effect...     

一类仿射非线性系统的概率密度函数形状控制

针对一类仿射非线性有界动态随机系统,提出一种最优概率密度函数（PDF）跟踪控制算法,使得系统的输出PDF跟踪给定的PDF．首先利用线性B样条解耦得到仿射非线性状态方程和PDF逼近方程,使PDF跟踪转化为状态方程输出权值的跟踪;然后采用线性时变序列逼近方法将非线性系统转化为线性时变系统,通过对线性系统的迭代运算得到非线性系统的最优跟踪控制器,从而实现最优PDF跟踪．理论分析和仿真实验均表明了所提出算法的有效性．