An integrated testbed for wireless multimedia computing

A testbed has been constructed to evaluate node architectures that support multimedia applications and services across a wireless network. Using this testbed, a low bitrate subband video compression algorithm has been prototyped in a field programmable gate array (FPGA) and evaluated for video networking across bandwidth-limited RF channels. A radio interface has been prototyped in an FPGA and a common applications programming interface (API) has been developed to allow experimentation with multiple radios. This testbed has been used to evaluate node performance under two different wireless applications: 1) simultaneous video and data networking (VTALK) and 2) TCP/IP utilities such as FTP and telnet. Based on this evaluation, the design of a battery-operated high throughput wireless multimedia node is presented.     

How to handle the inelastic collapse of a dissipative hard-sphere gas with the TC model

The inelastic hard sphere model of granular material is simple, easily accessible to theory and simulation, and captures much of the physics of granular media. It has three drawbacks, all related to the approximation that collisions are instantaneous: 1) The number of collisions per unit time can diverge, i.e. the “inelastic collapse” can occur. 2) All interactions are binary; multiparticle contacts cannot occur and 3) no static limit exists. We extend the inelastic hard sphere model by defining a duration of contact t _c such that dissipation is allowed only if the time between contacts is larger than t _c . We name this generalized model the TC model and discuss it using examples of dynamic and static systems. The contact duration used here does not change the instantaneous nature of the hard sphere contacts, but accounts for a reduced dissipation during “multiparticle contacts”. Kinetic and elastic energies are defined as well as forces and stresses in the system. Finally, we present event-driven numerical simulations of situations far beyond the inelastic collapse, possible only with the TC model.     

Composite substrate material for surface acoustic-wave oscillator

Surface acoustic-wave (SAW) oscillators have advantageous features compared with other technologies. The Y-128° LiNbO₃ is a well-known, high electromechanical-coupling SAW material, but its usefulness is limited because of its poor temperature-stability property. The AlN films have some excellent characteristics, such as high SAW velocity, stable chemical properties, and high-temperature stability. In this research, different thickness AlN films were sputtered on Y-128° LiNbO₃ to be a composite substrate for the SAW oscillator. As AlN film thickness increased, the temperature coefficient of frequency (TCF) value of the oscillator varied from −76.32 ppm/°C to −28.81 ppm/°C giving an improvement in the TCF of 62.25%. The oscillator frequency at 25°C also varied from 40.0909 MHz to 41.6221 MHz, giving an improvement in the oscillator frequency of 3.8%. The composite substrate (AlN/Y-128° LiNbO₃) can enhance the oscillator frequency and effectively improve the poor temperature stability for the SAW oscillator.     

差分隐私保护参数ε的选取研究

2006年,差分隐私保护作为一种新的隐私保护范式出现,因其不需要攻击者先验知识的假设,而被认为是一种非常可靠的保护机制。然而,作为隐私保护技术的主要参数ε的意义对于一般用户而言不十分明确。鉴于此,提出一个新的攻击模型,可以用来选取参数ε的值。详细分析了该攻击模型的特点,通过理论证明和模型的实证分析,最后给出了一个参数ε的选取计算式。     

支持动态策略更新的半策略隐藏属性加密方案

基于密文策略的属性加密被认为适用于云存储的环境,但当数据拥有者需要更新访问策略时,现有的更新方式因受数据的规模和属性集的大小的限制,会使数据拥有者增加相应的计算开销和通信开销。同时,以明文形式存放在云端的访问策略也会造成用户数据的隐私泄露。针对以上2个问题,提出了一种支持动态策略更新的半策略隐藏属性加密方案,使用所提方案进行策略更新时,用户的计算开销减少,大量的计算由云服务器承担。由于使用了半策略隐藏,用户的具体属性值不会泄露给其他任何第三方,有效保护了用户的隐私。此外,所提方案可以支持任何形式的策略更新,在标准模型下证明了方案是自适应选择明文攻击（CPA）安全的。     

Surface Charge Reversal Method for High‐Resolution Inkjet Printing of Functional Water‐Based Inks

Printed electronics is a rapidly growing area of research being explored for the manufacture of large‐area and cost‐effective electronic devices by the patterned application of functional inks. There are challenges associated with processing the inks compatible with inkjet printing technology and developing efficient methods to successfully obtain the desired features, particularly when it comes to metal and metal–organic complex inks. Here, a reliable method is developed to achieve a sophisticated microstructured pattern using the inkjet printing technique assisted by a surface charge reversal effect. In addition, a procedure is formulated to obtain good quality, stable metal–organic water‐based inks compatible with salts of a variety of transition metals and rare earths, without the need for additional volatile solvents. A feasible and water‐based ink formulation combined with a simple and noninvasive surface charge reversal treatment constitutes a major step toward the manufacture of high‐resolution, inorganic patterned thin films on hydrophobic substrates using inkjet printing. These outcomes lead to the path of effective fusion of inorganic and organic heterointerfaces by simples designing and printing.     

Crystallography of Interfaces and Grain Size Distributions in Sr‐Doped LaMnO3

Grain‐boundary plane distributions (GBPDs), grain size distribution (GSDs), and upper tail departure from log‐normal GSDs were quantified in dense and porous La_0.8Sr_0.2MnO₃ samples to understand expected microstructures in solid oxide fuel cells. Samples were sintered at 1450°C for 4 h and then annealed between 800°C and 1450°C. The GBPDs and normalized GSDs reached steady state during sintering and little variation occurred during annealing. The GBPDs were nearly isotropic, with the relative areas of {001} planes being slightly higher than random (and the relative areas of {111} planes being less than random). The porous sample had an almost identical GBPD, whereas the almost isotropic pore boundary plane distribution was essentially opposite to the GBPD. The upper tails of the experimental GSDs, and several theoretical distributions, were characterized using peaks‐over‐threshold analysis. Dense samples, and all normal grain growth models, exhibit lower frequencies of large grains in the upper tail than would a log‐normal distribution, and the experimental distributions are similar to the Mullins distribution. Porous samples, however, have an anomalous increased frequency of large grains in the upper tail, as compared to all the model distributions, even though other metrics of the microstructure indicate the dense and porous systems are similar.     

Improvement in the thermoelectric properties of CaMnO3 perovskites by W doping

Perovskite manganites CaMn_1?y W _y O₃ (0 ≤ y ≤ 0.05) were synthesized using solid-state reaction technique. The influence of W doping on the structure, charge carrier transports and phonon scattering of CaMnO₃ was investigated. Doping was found to increase the carrier concentration, leading to enhanced electrical conductivity and decreased Seebeck coefficient. In addition, it decreased the thermal conductivity of CaMnO₃, which was believed to associate with decreased phonon mean path and doping-induced MnO₆ octahedral distortion, as evidenced by the increased orthorhombicity. A twofold increase of figure of merit (ZT) of 0.15 at 973 K was observed in CaMn_0.99W_0.01O₃, compared with the undoped CaMnO₃.     

Dysfunction of Endocytic Kinase AAK1 in ALS

Mechanisms of human mutant superoxide dismutase 1 (SOD1)-induced toxicity in causing the familial form of amyotrophic lateral sclerosis (ALS) remain elusive. Identification of new proteins that can selectively interact with mutant SOD1s and investigation of their potential roles in ALS are important to discover new pathways that are involved in disease pathology. Using the yeast two-hybrid system, we identified the adaptor-associated kinase 1 (AAK1), a regulatory protein in clathrin-coated vesicle endocytic pathway that selectively interacted with the mutant but not the wild-type SOD1. Using both transgenic mouse and rat SOD1-linked familial ALS (FALS) models, we found that AAK1 was partially colocalized with the endosomal and presynaptic protein markers under the normal physiological condition, but was mislocated into aggregates that contained mutant SOD1s and the neurofilament proteins in rodent models of ALS in disease. AAK1 protein levels were also decreased in ALS patients. These results suggest that dysfunction of a component in the endosomal and synaptic vesicle recycling pathway is involved in ALS pathology.     

3D Acoustofluidics via Sub-Wavelength Micro-Resonators

Precise acoustic micromanipulation is emerging as an important tool in biomedical research, where acoustic forces have the advantage of being contact-free, label-free, and biocompatible. Conventional acoustofluidic approaches, however, produce device-scale effects that limit the ability to locally target acoustic energies at the microscale. In this study, we demonstrate an approach to generate designed and highly local acoustic fields using 3D resonant mass-spring microstructures, achieving local acoustic field gradients on the order of microns, orders of magnitude smaller than the fluid wavelength. In doing so, rapid and spatially defined controllable micromanipulation, including particle capture, transport, and patterning using arbitrarily arranged micro-resonator arrays is demonstrated. This sub-wavelength, 3D acoustofluidic approach results in highly localized and defined micromanipulation, with potential applications across sample preparation, cell analysis, and diagnostics.