Distributed bandwidth allocation based on alternating evolution algorithm

In a network, end nodes have to compete for bandwidth through some distributed congestion control algorithms. It is a great challenge to ensure the efficiency and fairness of the distributed control algorithms. TCP congestion control algorithms do not perform well in terms of their efficiency and fairness in high speed networks. In this paper, we propose a novel asymptotic evolution algorithm based on the Logistic Model to allocate limited bandwidth resource. The algorithm introduces an explicit bandwidth pre-allocation factor. The factor is carried by the packet and is computed in routers based on the information of the router capacity, the aggregate load, and the instantaneous queue length; therefore the algorithm does not require the routers to keep the per-flow state. According to this pre-allocation bandwidth factor, the senders asymptotically adjust their sending rate and the bandwidth factor changes asymptotically along with the variation of the aggregate load and the queue length in the routers; therefore the sending rate and the pre-allocation bandwidth factor form alternating evolution and eventually reach a steady state.     

地理信息系统在精导武器中的应用研究

首先简述了地理信息系统的概念、特征和组成,结合精确制导武器在信息化战争中的运用,分析了地理信息系统在精确制导武器的直接运用和间接影响,并对地理信息系统在精确制导武器上应用的前景进行了展望。     

miRNA检测技术进展

miRNA做为一种非常重要的非编码蛋白的RNA.广泛存在于植物、病毒、哺乳动物当中.因其在细胞增殖、细胞死亡、肿瘤发生和哺乳动物细胞生长中重要的调节功能,其检测技术也受到越来越多的关注,很多关键的检测技术,比如印迹技术,阵列杂交技术,反转录PCR技术等等都在miRNA的检测中发挥了巨大的实用价值.该文基于此对miRNA近几年的检测技术进行了具体的综述.     

ATmega16与PC机的移动机器人定位系统研究

为提高移动机器人定位系统的可靠性,设计了组合使用光纤陀螺仪、光电码盘和超声波传感器的定位系统,系统采用CAN总线的数据传输方式。ATmega16采集各传感器数据,再以CAN总线方式传输给PC机;PC机平台综合处理光纤陀螺、光电码盘与超声波返回的数据,实现移动机器人定位。定位算法以航迹推算为主,超声波传感器起辅助定位作用。实验表明定位系统可靠有效。     

Globally Exponential Stability for Delayed Neural Networks Under Impulsive Control

In this paper, the dynamic behaviors of a class of neural networks with time-varying delays are investigated. Some less weak sufficient conditions based on p-norm and ∞-norm are obtained to guarantee the existence, uniqueness of the equilibrium point for the addressed neural networks without impulsive control by applying homeomorphism theory. And then, by utilizing inequality technique, Lyapunov functional method and the analysis method, some new and useful criteria of the globally exponential stability with respect to the equilibrium point under impulsive control we assumed are derived based on p-norm and ∞-norm, respectively. Finally, an example with simulation is given to show the effectiveness of the obtained results.     

Network coding-based reliable multicast in wireless networks

Reliable multicast, the lossless dissemination of data from one sender to a group of receivers, has a wide range of important applications. Recently, network coding has been applied to the reliable multicast in wireless networks, where multiple lost packets with distinct intended receivers are XOR-ed together as one packet and forwarded via single retransmission, resulting in a significant reduction of bandwidth consumption. However, the simple XOR operation cannot fully exploit the potential coding opportunities and finding the optimal set of lost packets for XOR-ing is a complex NP-complete optimization problem. In this work, we intend to move beyond the simple XOR to more general coding operations. Specifically, we propose two new schemes (a static scheme which repeatedly retransmits one coding packet until all intended receivers receive it and a dynamic scheme which updates the coding packet once one or more receivers receive it) to encode packets with more general coding operations, which not only can encode lost packets with common intended receivers together to fully exploit the potential coding opportunities but also have polynomial-time complexity. We demonstrate, through both analytical and simulation results, that the proposed schemes can more greatly reduce the bandwidth requirement than the available coding-based schemes, especially in the case of high packet loss probabilities and a larger number of receivers. This reduction can vary from a few percents to over 15% depending on the packet loss probabilities and the number of receivers.     

Robust stability of nonlinear plants with a non-symmetric Prandtl-Ishlinskii hysteresis model

In this paper, robust stability of nonlinear plants represented by non-symmetric Prandtl-Ishlinskii (PI) hysteresis model is studied. In general, PI hysteresis model is the weighted superposition of play or stop hysteresis operators, and the slopes of the operators are considered to be the same. In order to make a hysteresis model, a modified form of non-symmetric play hysteresis operator with unknown slopes is given. The hysteresis model is described by a generalized Lipschitz operator term and a bounded parasitic term. Since the generalized Lipschitz operator is unknown, a new condition using robust right coprime factorization is proposed to guarantee robust stability of the controlled plant with the hysteresis nonlinearity. As a result, based on the proposed robust condition, a stabilized plant is obtained. A numerical example is presented to validate the effectiveness of the proposed method.     

Microfluidic synthesis of copper nanofluids

Copper nanofluids have been chemically synthesized by using home-made microfluidic reactors and by using a boiling flask-3-neck. The influence of flow rates of reactants, reactants concentrations, and surfactant concentrations on copper particle size and size distribution has been investigated. It has been found that neither of them has much influence on particle size and size distribution of copper nanoparticles synthesized in microfluidic reactors due to the fast and efficient mass diffusion in microscale dimension. The copper nanoparticles have an average size of about 3.4 nm with a relatively narrow size distribution of around 22% evaluated by the coefficient of variation. While the average size of copper nanoparticles synthesized by flask method changes from 2.7 to 4.9 nm with a coefficient of variation larger than 30%, depending on concentrations of [Cu(NH₃)₄]·(OH)₂ and surfactant sodium dodecylbenzenesulfonate. In addition, by using microfluidic reactors the synthesis time of copper nanofluids can be reduced as much as one order of magnitude, from ~10 min to ~28 s.     

A simple photolithography method for microfluidic device fabrication using sunlight as UV source

A straightforward method for microfluidic devices fabrication using sunlight as the ultraviolet (UV) source is established in this work. This method is based on photolithography, but obviates the need for specialized UV exposure facility. Substrates coated with photoresist were placed directly under sun in a perpendicular direction to the sunlight for exposure. Exposure conditions were optimized for patterning features with different kinds of photoresist, photoresist of different thicknesses and dimensions. Exposure time can be adjusted to obtain designed features on a mask with good lateral structure according to the energy measured by UV meter (with a constant intensity of UV in sunlight). Masters produced under optimum exposure conditions were used for the fabrication of several microfluidic devices with different materials, structures, or functions. Resultant devices were shown eminently suitable for microfluidic applications such as electrophoretic separation, multiple gradient generator, and pneumatic valve-based cell culture. This photolithographic method is simple, low cost, easy to operate, and environmental friendly. Especially, the masters can be obtained in parallel simultaneously, which is suitable for chip fabrication for mass production. It is also more attractive for the laboratories, in which the support for photolithographic facility is not available.