借力新媒体 谋求新发展——浅谈传统媒体如何应对新媒体的冲击

新媒体的蓬勃发展给传统媒体带来了挑战,也为传统媒体的转型升级创造了机遇。本文从微博入手,深入分析新媒体为报纸等传统媒体提供了丰富的新闻源,传统媒体可以利用微博、网站等新媒体重新整合优势资源,实现"报网互动"、"报微互动",开创全新的媒体运作模式。     

本刊声明

正本刊已许可中国学术期刊(光盘版)电子杂志社在中国知网及其系列数据库产品中以数字化方式复制、汇编、发行、信息网络传播本刊全文.该社著作权使用费与本刊稿酬一并支付.作者向本刊提交文章发表即视为同意我刊上述声明.     

基于60°坐标系的SVPWM过调制算法

传统的空间矢量脉宽调制(SVPWM)在正交坐标系中实现时,涉及的计算量较大,相应的过调制算法更为复杂.为了更利于实时操作,文中分析了60°坐标系下SVPWM算法的特点,提出了一种计算量小,易于实现的过调制算法.该算法能统一处理参考电压矢量整个调制区域,不需要计算保持角.在六阶梯波模式中,该算法不需要计算参考电压实际角度来选取基本电压矢量,仅需要根据原来没有过调制处理时计算得到的基本电压矢量作用时间做出选择.理论分析和实验结果证明该算法能节省大量计算时间.     

风储互补微网对配电网可靠性的影响

随着分布式发电技术的不断推广和发展,大量DG(分布式发电)以微网形式接入配电网.文中以风储互补微网为对象,根据互补微网在配电网中的运行方式,采用蒙特卡洛仿真算法,从负荷点和系统两个层面上给出了配电网中常用的几项可靠性指标;在分析了随机电源特点的基础上,建立风储互补微网可靠性评估模型;根据传统配电网可靠性计算结果对风力DG进行选址,在确定储能配置后形成了计划型孤岛范围;提出由于风储微网内负荷和风力DG出力的时变性,在孤岛内有可能发生储能放电过量,从而导致微网解列的二次故障问题.对风储互补微网接入后的配电网的蒙特卡洛可靠性仿真结果表明,风储互补微网能有效提高配电系统的可靠性.     

Novel laminated multiferroic heterostructures for reconfigurable microwave devices

Voltage tuning of magnetism is fundamentally and technically important for fast, compact and ultra-low power electronic devices. Multiferroic heterostructures,simultaneously exhibiting distinct ferroelectric and ferromagnetic properties, have caught a lot of attentions because of the capability of controlling magnetism by a voltage via a strain-mediated magnetoelectric（ME） coupling. In these materials, a voltage-induced strain is involved to create an effective magnetic field and change ferromagnetic resonance frequency in the coupled ferromagnetic phases through magnetoelastic interactions. Therefore, the devices made of such materials are compact, ultra-fast and energy efficient,providing new functionalities for microwave components.This paper will review the recent progress of multiferroics and their applications in microwave devices from different aspects, including the creation of the novel laminated multiferroic heterostructures with a strong ME coupling, the realization of the multiferroics based on tunable microwave signal processors and the investigation of nonvolatile tuning of microwave properties using ferroelastic domain switching in multiferroic heterostructures. These tunable multiferroic heterostructures and devices offer great opportunities for realizing the next generation of tunable magnetic microwave components, ultra-low power electronics and spintronics.     

Paleodietary changes by penguins and seals in association with Antarctic climate and sea ice extent

Positioned near the top of the food web, the dietary composition of Antarctic penguins and seals can be an excellent indicator of the regional food web and thus the status of the marine ecosystem. The dietary composition of modern penguins and seals has been well investigated; a long-term time series of data on penguin and seal diets, however, are rare. Such data, especially any predating the initiation of human harvesting of fish, whales and seals in Antarctica, are crucial for understanding and predicting responses of regional marine food webs to natural climate changes. Here we review recent progress on research of paleodietary change in Antarctic penguins and seals, specifically the Adelie penguin （Pygoscelis adeliae） and Antarctic fur seal （Arctocephalus gazella）. These studies indicate that the dietary changes of penguins correspond quite well with fluctuations in climate and sea ice extent during the Holocene. The depleted δ15N ratios found in modern Adelie penguins support the ＂krill surplus hypothesis＂ in relation to historic human depletion of krilleating fish, seals and whales.     

Qos约束随机游走在移动自组网资源发现中的应用

针对目前移动自组网随机游走资源发现协议在请求转发过程中没有考虑Qos（Quality of Service）,使得选取的资源发现路径常常无法达到用户的要求,提出了将Qos约束条件应用到随机游走资源发现协议中,节点在随机转发请求分组时搜集邻居节点的剩余带宽、连接延迟和丢包率等信息,通过Qos计算公式计算出节点的Qos值,根据Qos值决定转发节点的选择或者丢弃,最终找到一条能够很好满足用户Qos需求的资源发现路径。     

基于反向传播树的传感网路由算法

本文在分析无线传感器网络LEACH(Low-Energy Adaptive Clustering Hierarchy)协议的基础上,提出了一种新的基于反向传播树的聚簇路由协议BPT-CR(Back Propagation Tree based Cluster Routing),该协议簇头的选择综合考虑节点剩余能量和数据融合等因素,采用周期性轮换机制,有利于延长传感器网络的生存时间;路由的选择采用基于地理位置的反向传播树路由策略,有利于降低路由选择的复杂度,提高网络的吞吐量。     

投稿指南

正1来稿要求1.1稿件要素稿件内容必须包括:题目、作者姓名、作者所在单位、所在省份和城市、邮政编码、中文摘要、关键词、英文题目、作者英文姓名、作者英文单位、英文摘要、英文关键词、正文、致谢(非必选)、参考文献等内容。     

正交试验优选糖网合剂的提取工艺

目的:优选糖网合剂的水提工艺.方法:采用L9(34)正交试验,以桂皮醛含量和干膏率为评价指标,以加水量、煎煮次数和煎煮时间为考察因素,确定糖网合剂的最佳水提工艺.结果:最佳优化工艺条件为加12倍水,提取三次,每次0.5小时.结论:优选出的提取工艺合理可行,质量可控.