Collaborative Multiple Access And Energy-Efficient Resource Allocation in Distributed Maritime Wireless Networks

With the rapid increasing of maritime activities, maritime wireless networks(MWNs) with high reliability, high energy efficiency, and low delay are required. However, the centralized networking with fixed resource scheduling is not suitable for MWNs due to the special environment. In this paper,we introduce the collaborative relay communication in distributed MWNs to improve the link reliability, and propose an orthogonal time-frequency resource block reservation based multiple access(RRMA) sche...     

短期负荷预测Volterra滤波器间隔采样模型

针对现有Volterra滤波器模型按混沌轨道逐点训练的模式易发生训练不充分或过拟合现象并最终影响短期负荷预测效果的问题,提出了依据相空间邻近轨道演化相似性特点,建立基于高阶非线性Volterra滤波器(HONFIR)的短期负荷预测多步预测模型(MSF-HONFIR).通过定义距离相似度、趋势相似度来衡量轨道演化相似性,提出了负荷吸引子邻近轨道判别的新方法.在MSF-HONFIR模型基础上将原始负荷序列分解为多个子序列并分别对各个子序列建立预测模型,显著削弱了系统累积误差.短期负荷预测仿真结果表明MSF-HONFIR模型的多步预测性能优于原有HONFIR模型.     

电力系统中无触点有载调压装置的研究与应用

随着科技和经济的发展,大量用电设备对供电质量的要求越来越高,传统的有载调压变压器由于其固有的缺陷而不能满足要求。现有的通过继电器切换或炭刷来调节电压的交流稳压器通常用在低压用户端,而且也存在一些弊端。目前正研究的无触点有载调压变压器,由于晶闸管是直接用于主电路,因此需要大量的晶闸管串并联,控制复杂,体积大,价格高,并且技术也未成熟,并没有推向市场。基于此,本文提出了一种配电系统的无触点有载调压拓扑结构,它具有上述装置的优点,同时又克服了其缺点。本文除了对其工作原理,主电路进行了介绍外,还重点对暂态无冲击控制条件进行了分析,最后通过实验对该设备进行了验证。     

微机保护装置中USB通讯接口的设计

文章提出一种USB通讯接口的设计方案,首先介绍了USB总线的优点和高性能USB控制器芯片PDIUSBD12的特点,其次介绍了USB硬件接口电路设计原理,最后介绍了USB通讯接口的程序编写方法和实用性。     

微晶玻璃-陶瓷复合曲面板的生产工艺研究

本文通过研究微晶玻璃-陶瓷复合材料在高温下软化流动的特征和晶粒相对位移的特点,论述了复合平板加热、加压弯曲过程中的温场分布规律,并由此制定出合理的温度制度,使复合板微晶表面和坯体在合理的温度制度、温场分布制度下同步弯曲成为所设计的曲面。     

S波段微波照射对大鼠免疫功能的影响

用S波段高功率微波照射大鼠,观察大鼠白细胞计数、淋巴细胞数、T细胞及其亚群和免疫球蛋白的变化,以期了解S波段高功率微波照射对大鼠免疫功能的影响.结果表明,S波段高功率微波照射可以引起大鼠白细胞水平降低,T细胞亚群出现兴奋效应,免疫球蛋白早期出现不同程度的降低,表现出低剂量刺激而高剂量抑制的效应.     

可极化大地上CSAMT激发极化效应的研究

采用Cole-Cole模型来模拟大地可极化,对三层水平地层且中间层为极化层的可控源音频大地电磁激电测深的视电阻率进行理论计算,分析极化参数对视电阻率曲线的影响规律．采用广义逆方法对三层水平地层且中间层为极化层的模型进行了理论的反演,初步得出：提取极化大地上可控源音频大地电磁测深数据中的激电效应是可能的。     

锚杆锚固质量检测方法及应用

对锚杆锚固质量的检测一直为工程界所关注,本文比较了拉拔试验与声波反射检测锚杆锚固质量的方法,介绍了两种方法的基本原理以及相关的技术规定。鉴于拉拔试验方法上的不足,详细阐明了声波检测方法及其基本原理,并列举了应用于某高速公路隧道工程检测锚杆锚固质量检测的例子。     

快速冷却条件下螺杆轴向振动对 HDPE 挤出制品拉伸性能的影响

采用电磁动态塑化挤出机挤出高密度聚乙烯(HDPE)片材,研究了片材在快速冷却条件下,振动力场对其拉伸性能、结晶度、晶粒尺寸等的影响。结果表明,施加振动力场后,HDPE制品的拉伸性能、熔点和结晶度都得到提高,晶粒尺寸增大,但晶型未发生明显的改变。     

Effect of methyl jasmonate on quality and antioxidant activity of postharvest loquat fruit

BACKGOUND: Loquat fruit is rich in natural antioxidants and has shown a remarkably high antioxidant activity. To search for an effective method for maintaining or even improving antioxidant activity during postharvest storage, we investigated the effect of 10 µmol L^?1 methyl jasmonate (MeJA) treatment on levels of major individual sugars and organic acids, total phenolics, total carotenoids, total flavonoids and antioxidant activity in loquat fruit during storage at 1 °C for 35 days. RESULTS: The MeJA‐treated fruit exhibited significantly lower levels of respiration rate, ethylene production, phenylalanine ammonia‐lyase and polyphenol oxidase activities, and higher levels of sugars, organic acids, total phenolics and total flavonoids than control fruit. Meanwhile, the treatment also maintained significantly higher antioxidant activity as measured by the scavenging capacity against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), superoxide and hydroxyl radicals, and by the reducing power test compared to the control. There was a significant positive linear relationship between total phenolic content and DPPH radical scavenging activity. CONCLUSION: MeJA treatment can improve the quality and functional properties of harvested loquat fruit by maintaining a higher level of antioxidants and enhancing antioxidant activity. Copyright © 2009 Society of Chemical Industry