Jitter smoothing and traffic modeling for MPEG-2 video transport over ATM networks

In this article, we study how to deal with jitter when a variable-bit-rate (VBR) MPEG-2 video is delivered through asynchronous transfer mode (ATM) networks. First, the MPEG-2 system and its timing model are reviewed and difficulties introduced by ATM cell delay jitter are elucidated. Second, approaches to smoothing network jitter for both constant-bit-rate and VBR traffic are reviewed. A novel approach to modeling the end-to-end MPEG-2 packet generation and arrival process in the presence of network jitter is next presented. Based on this model, the buffer behavior of the MPEG-2 transport stream system target decoder is simulated. Simulation results show that jitter significantly affects the required decoder buffer size and packet loss ratio. © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 332–339, 1998     

Resource allocation for multimedia streaming over the Internet

This paper addresses the resource allocation problem for multiple media streaming over the Internet. First, we present an end-to-end transport architecture for multimedia streaming over the Internet. Second, we propose a new multimedia streaming TCP-friendly protocol (MSTFP), which combines forward estimation of network conditions with information feedback control to optimally track the network conditions. Third, we propose a novel resource allocation scheme to adapt media rate to the estimated network bandwidth using each media's rate-distortion function under various network conditions. By dynamically allocating resources according to network status and media characteristics, we improve the end-to-end quality of services (QoS). Simulation results demonstrate the effectiveness of our proposed schemes     

Plasmonic waveguides mediated energy transfer between two distant quantum dots

We investigate theoretically the radiative energy transfer between two distant quantum dots (QDs) mediated by the guided modes of Ag nanowire. The cross decay rate between the two quantum dots is derived with Markov approximation and the decay behaviors of the superradiant state and the subradiant state of quantum dots are exhibited. Due to the interference of the radiation emitted by the two QDs, the cross decay rate, the decay rates of the superradiant state, and the subradiant state show oscillation behaviors. This reveals that energy transfer from one QD to a distant QD can be controlled by adjusting the distance between the two QDs due to the periodicity of the cross decay rate.     

浓香型大曲的酯化力与酯分解率研究

应用传统酯化力测定方法和有机相中酯化力测定方法测定了大曲中的酯化力。结果表明，大曲最有较强的酯化能力，且曲外层的酯化力高于曲心，新曲的酯化力高于陈曲，一等品曲高于二等品曲，二等品曲高于三等品曲。同时，对大曲的酯分解率进行了研究。     

Peer-to-peer based multimedia distribution service

Recently, there are many research interests in providing efficient and scalable multimedia distribution service. However, stringent quality-of-service (QoS) requirements for media distribution, as well as dynamically changing and heterogeneous network capacity in today's best effort Internet, bring many challenges. In this paper, we introduce a novel framework for multimedia distribution service based on peer-to-peer (P2P) networks. A topology-aware overlay is proposed in which hosts self-organize into groups. End hosts within the same group have similar network conditions and can easily collaborate with each other to achieve QoS awareness. In order to improve media delivery quality and provide high service availability, we further propose two distributed heuristic replication strategies, intergroup replication and intragroup replication, based on this topology-aware overlay. Specifically, intergroup replication is aimed to improve the efficiency of media content delivery between the group where a request is issued and the group where the content is stored. Also, intragroup replication is targeted at improving the availability of the content. Extensive simulation results show that the latency in our proposed architecture is 20% less than that of the FreeNet and 50% less than that of the randomly replication system. Simulation results also show that the video quality in our system is much better than that in the other two systems. Our P2P-based approach is also distributed, scalable, cost effective, and aware of the performance.     

浓香型大曲中酯化酶测定方法的研究

对浓香型大曲的酯化酶测定方法作了研究。建立有机相反应体系来代替方法的水相反应，与传统测定方法（需反应100h）相比，它能简单、快捷检测大曲质量，适合工业化生产的要求。有机相中酯化反应条件为：在30mL正庚烷有机反应介质中，35℃的条件下，0.15M的底物酸，己酸与乙醇的浓度比为1：1.25，加入15g（干曲）的大曲，仅用24h有比较出大曲酯化力的高低。     

肉品中β-受体激动剂类药物残留检测 技术研究进展

肉品中β-受体激动剂类药物残留问题严重影响着人体健康。近几年来暴露出来的肉品中β-受体激动剂类药物残留事件层出不穷, 为了加强监控, 越来越多的检测方法被建立起来, 极大地提高了肉品中β-受体激动剂类药物残留检测的效率。本文综述了检测肉品中β-受体激动剂类药物残留的色谱法、酶联免疫法、胶体金法和其他一些新方法的研究进展, 以及我国现行的β-受体激动剂类药物残留标准检测方法。对现有的检测方法的优缺点和发展阶段作了归纳总结, 并对β-受体激动剂类药物残留检测方法发展的方向提出了一些展望。未来的发展主要是一些特异性和灵敏度更高的快检方法和样品前处理更加简化的液质色谱联用法。     

塑料防雾剂的研究进展

一种理想的防雾剂应具有成本低、防雾效果好、持效期长的特点,且使用方便,对人体无危害。文中从五个方面阐述了塑料防雾剂的研究进展,添加纳米粒子作棚膜防雾剂;塑料膜用含氟表面活性防雾剂;防雾剂薄膜;多聚甘油脂肪酸酯塑料防雾剂;有机硅材料作为防雾材料。     

水生生物重金属富集规律研究

重金属对水生生物具有毒害作用,已被列入水中优先控制污染物名单。影响水生生物富集重金属的主要因素包括生活水域、生活习性、特殊生理形态及季节变化。水生植物可通过根、茎、叶等营养器官富集重金属,且不同植物对重金属的吸收方式、积累能力和耐受水平不同。水生动物则通过呼吸、粘附和食物链途径富集重金属,体内重金属含量与食物链层级无明显对应关系,摄食习惯是主要影响因素。此外,本研究总结近3年(2015～2017)我国近岸海域的重金属污染现状,以期为中国近岸海域中水生生物的保护和海洋资源的可持续利用提供参考依据。     

Cross-Layer Design for QoS Support in Multihop Wireless Networks

Due to such features as low cost, ease of deployment, increased coverage, and enhanced capacity, multihop wireless networks such as ad hoc networks, mesh networks, and sensor networks that form the network in a self-organized manner without relying on fixed infrastructure is touted as the new frontier of wireless networking. Providing efficient quality of service (QoS) support is essential for such networks, as they need to deliver real-time services like video, audio, and voice over IP besides the traditional data service. Various solutions have been proposed to provide soft QoS over multihop wireless networks from different layers in the network protocol stack. However, the layered concept was primarily created for wired networks, and multihop wireless networks oppose strict layered design because of their dynamic nature, infrastructureless architecture, and time-varying unstable links and topology. The concept of cross-layer design is based on architecture where different layers can exchange information in order to improve the overall network performance. Promising results achieved by cross-layer optimizations initiated significant research activity in this area. This paper aims to review the present study on the cross-layer paradigm for QoS support in multihop wireless networks. Several examples of evolutionary and revolutionary cross-layer approaches are presented in detail. Realizing the new trends for wireless networking, such as cooperative communication and networking, opportunistic transmission, real system performance evaluation, etc., several open issues related to cross-layer design for QoS support over multihop wireless networks are also discussed in the paper.