Minimum power assignment in wireless ad hoc networks with spanner property

Power assignment for wireless ad hoc networks is to assign a power for each wireless node such that the induced communication graph has some required properties. Recently research efforts have focused on finding the minimum power assignment to guarantee the connectivity or fault-tolerance of the network. In this paper, we study a new problem of finding the power assignment such that the induced communication graph is a spanner for the original communication graph when all nodes have the maximum power. Here, a spanner means that the length of the shortest path in the induced communication graph is at most a constant times of the length of the shortest path in the original communication graph. Polynomial time algorithm is given to minimize the maximum assigned power with spanner property. The algorithm also works for any other property that can be tested in polynomial time and is monotone. We then give a polynomial time approximation method to minimize the total transmission radius of all nodes. Finally, we propose two heuristics and conduct extensive simulations to study their performance when we aim to minimize the total assigned power of all nodes. The author is partially supported by NSF CCR-0311174.     

Reliable Ad Hoc Routing Based on Mobility Prediction

Reliability is a very important issue in Mobile Ad hoc NETworks (MANETs). Shortest paths are usually used to route packets in MANETs. However, a shortest path may fail quickly, because some of the wireless links along a shortest path may be broken shortly after the path is established due to mobility of mobile nodes. Rediscovering routes may result in substantial data loss and message exchange overhead. In this paper, we study reliable ad hoc routing in the urban environment. Specifically, we formulate and study two optimization problems. In the minimum Cost Duration-bounded Path (CDP) routing problem, we seek a minimum cost source to destination path with duration no less than a given threshold. In the maximum Duration Cost-bounded Path (DCP) routing problem, we seek a maximum duration source to destination path with cost no greater than a given threshold. We use a waypoint graph to model the working area of a MANET and present an offline algorithm to compute a duration prediction table for the given waypoint graph. An entry in the duration prediction table contains the guaranteed worst-case duration of the corresponding wireless link. We then present an efficient algorithm which computes a minimum cost duration-bounded path, using the information provided in the duration prediction table. We also present a heuristic algorithm for the DCP routing problem. In addition, we show that the proposed prediction and routing schemes can be easily applied for designing reliable ad hoc routing protocols. Simulation results show that our mobility prediction based routing algorithms lead to higher network throughput and longer average path duration, compared with the shortest path routing. This research was supported in part by ARO grant W911NF-04-1-0385 and NSF grant CCF-0431167. The information reported here does not reflect the position or the policy of the federal government.     

Energy conservation through resource-aware movement in heterogeneous mobile ad hoc networks

Energy conservation in mobile ad hoc networks is of paramount importance because most mobile nodes usually have very limited energy supply. Previous research on this issue focused on the design at the network or MAC or physical layer. In this paper, we study this problem from the new perspective of node mobility, i.e., analyzing the impact of node movement on energy conservation. In particular, armed with the inherent resource heterogeneity in mobile ad hoc networks, we propose a novel resource-aware movement strategy to make better use of some powerful nodes to achieve energy conservation. We also formulate the resource-aware movement as a NP-complete distance-constrained least-cost (DCLC) routing problem and propose an efficient heuristic solution. Extensive simulations have been used to demonstrate the effectiveness of the proposed schemes.     

《60分钟》与《东方时空》节目形态之比较

《60分钟》和《东方时空》是美中两国最具代表性的电视新闻杂志节目。为了进一步揭示这类节目的编辑规律,从四个方面对二者的节目形态进行比较分析。《60分钟》与《东方时空》都非常重视电视语言的合理运用,并逐步形成了各自的风格,但是在栏目设置、节目特征与形象设计、主持技巧等方面存在较大差异。     

论大众传媒参与下的国学教育与国学教育教师培养——以电视节目资源应用于课堂教学为例

国学是中华文化的集中体现,已作为一门必修课进入到很多中小学课堂。但是,目前存在着合格的国学师资普遍缺乏、国学教学形式比较单一等问题。本文以国学教育教师如何利用电视节目资源开展课堂教学为例,针对大众传媒参与下的国学教育与国学教育教师培养提出建议,以期能够帮助提升国学教育教师专业素养,提高中小学国学教育水平。     

论“全面小康”建设中的电视文化力

电视文化力,是文化力的核心.在"全面小康"建设中,既要充分发挥它在引导文化、拉动经济、化育民众等方面的能动作用,又要与时俱进、努力创新,以不断增强其核心竞争力,始终保持其先进性.     

电视品牌构造体系初探

品牌战略被称为注意力经济时代企业竞争的重要利器,作为企业构造品牌战略所依托的核心载体,电视媒体同样需要构造出自身强大的品牌体系。电视品牌依靠品牌知名、品牌联想、品牌认知、品牌忠诚、及附着其上的专属资产建构品牌价值体系,同时借助电视产品核心元素的品牌化,也即是主持人及栏目的品牌化,打造品牌竞争力。     

粤港功夫影视中舞狮、舞龙的非文本诗学意义

从粤港影视传媒中黄飞鸿、霍元甲、李小龙等,影视中舞狮、舞龙及采青斗胜的民间节庆文化中,发掘岭南珠三角地带民俗因子里的文化想像。致力于从非文本诗学角度来剖析黄飞鸿影视的审美趣味和承传文化精神变迁的心路历程,为初步建构关于非文本诗学提供新的案例。     

电视广告决策支持系统

本文从分析广告运作决策中关键的问题入手,提出了支持电视广告决策的数学模型,定义了电视广告影响力指数,在此基础上进行了电视广告决策支持系统的建立,为电视广告决策人员进行科学的决策提供了一种辅助工具。     

布什政府中东国际广播效能评析

为了缓解“9·11”事件后中东强烈的反关甚至仇美情绪，布什政府决定加大对中东的广播宣传。布什政府认为，从整体上讲，中东的媒体环境对美国是“不友好的”，甚至是“充满敌意的”；中东民众所接触到的有关美国的信息是“不真实的”，甚至是“被歪曲的”。这些“不真实”、“不可靠”的信息误导了中东民众，使他们对美国产生了“误解”和“仇恨”。正是基于这种逻辑，布什政府在“9·11”事件后不久很快建立起包括萨瓦电台、自由电视台、自由阿富汗电台等在内的中东广播网络，目的是宣传美国的外交政策，传播美国的价值观，舒缓中东民众对美国的敌意，增进中东民众对美国的好感。但是从2002年初至今的情况来看，布什政府对中东的广播宣传并没有达到预期的效果，其核心原因在于中东民众对美国中东政策的不满。