互联网大数据技术在智慧交通发展中的应用

随着互联网大数据技术的发展,各种互联网+交通的新业态不断涌现,行业内出现了大量丰富的数据资源。在交通强国建设背景下,更好地利用互联网大数据技术为智慧交通发展赋能成为重要任务。针对传统信号控制系统优化频率低,数据采集设备完备度差等缺陷,采用网约车轨迹大数据技术研究智慧信号控制优化系统,介绍了系统架构、特征和信号控制优化技术。该系统在济南、武汉和柳州等城市的实践结果表明,在不依赖渠化及路口改造的前提下,仅通过信号控制优化及软件升级的方式,能有效地降低重点路段和路口的工作日早晚高峰平均延误时间和停车次数等关键指标,其降幅可达10%～20%,能够有效缓解交通拥堵现状。     

改进信号子空间结合维纳滤波的语音增强算法

针对现有语音增强算法噪声残留和语音失真,不能同时达到最小这一问题,提出了一种改进的信号子空间结合维纳滤波法,进行两级语音增强。第一级利用听觉掩蔽参数改进信号子空间的增益矩阵,经处理后,可以有效降低语音失真度,并初步提高信噪比。然后利用维纳滤波算法对增强后的语音信号进行加强。实验结果表明,相比传统的信号子空间算法、维纳滤波算法,可以有效地减少语音信号中的残留噪声、降低语音信号的失真度、提升语音信号的整体质量。     

基于STC15F2K60S2的便携式低频信号发生器设计

设计了低频信号发生器,通过按键输入或Pc机串口命令输入控制信号类型、频率、幅值,采用TLC5615输出相应的波形,以240％128图形点阵液晶显示。采用C语言编程,可实现正弦波,三角波,锯齿波和方波四种波形的产生,波形无失真,频率准确。     

非线性阵列Khatri-Rao子空间宽带DOA估计

针对非线性阵列,基于Khatri-Rao子空间概念提出一种新的无预估角宽带到达角(direction-of-arrive,DOA)估计方法. 从Khatri-Rao子空间虚拟阵列导向矢量出发,利用虚拟阵列所增加的维数,以流形分离技术构造与到达角无关的宽带聚焦矩阵,无需预估角且估计性能良好. 采用Root-MUSIC算法避免传统算法中的谱峰搜索过程,降低了计算量. 仿真结果表明,该方法与需要预估角的已有Khatri-Rao子空间宽带DOA估计方法FKR-RSS相比,具有相近的估计精度和目标分辨力. 在信号源数大于阵元数的情况下,其性能优于FKR-RSS.     

提高空间谱算法分辨率的DOA估计

针对传统MUSIC算法在低信噪比,小快拍数等非理想条件下分辨率下降的问题,提出了改进的基于子空间投影的MUSIC测向算法. 该算法充分利用子空间信息,采用新的特征值校正方法对噪声子空间进行加权,并与加权信号子空间投影进行空间谱合成,得到新的空间谱函数. 搜索函数极大值,就能得到来波方向. 新方法既保
留了噪声子空间算法的高分辨性能,又保留了信号子空间算法的稳定性. 计算机仿真和实测数据表明新方法有效.     

高速电路中电源/地平面间同步开关噪声的抑制研究

提出一种将介质型电磁带隙结构与电源平面分割技术相结合,用于抑制高速电路电源/地平面间同步开关噪声的新方法.利用Ansoft HFSS建立相应三维电磁仿真模型并对其进行数值仿真,结果表明:若以-40 dB为噪声隔离标准,噪声可在0.01～0.66 GHz与0.91～4.11 GHz范围内得到有效抑制,并且噪声最大抑制深度...     

Protein kinase C and phospholipase D: intimate interactions in intracellular signaling

Diacylglycerol (DAG) was discovered as a potent lipid second messenger with protein kinase C (PKC) as its major cellular target more than 25 years ago. There is increasing evidence of significant complexity within lipid signaling, and the classical DAG-PKC model no longer stands alone but is part of a larger bioactive lipid universe involving glycerolipids and sphingolipids. Multiple layers of regulation exist among PKC- and DAG-metabolizing enzymes such as phosphatidylcholine (PC)-specific phospholipase D, and cross-talk exists between the glycerolipid and sphingolipid pathways, with PKC at the center. Currently, there is intense interest in the question of whether DAG derived from PC can function as a lipid second messenger and regulate PKC analogous to DAG derived from phosphatidylinositol-4,5-bisphosphate (PIP₂). To address these issues and incorporate DAG-PKC and other signaling pathways into an expanded view of cell biology, it will be necessary to go beyond the classical approaches and concepts.Received 29 November 2004; received after revision 18 January 2005; accepted 4 March 2005This work is dedicated to the memory of Dr. Yasutomi Nishizuka, the discoverer of protein kinase C, who was both a gentleman and a scientist.     

Cellular responses to mild heat stress

Since its discovery in 1962 by Ritossa, the heat shock response has been extensively studied by a number of investigators to understand the molecular mechanism underlying the cellular response to heat stress. The most well characterized heat shock response is induction of the heat shock proteins that function as molecular chaperones and exert cell cycle regulatory and anti-apoptotic activities. While most investigators have focused their studies on the toxic effects of heat stress in organisms such as severe heat stress-induced cell cycle arrest and apoptosis, the cellular response to fever-ranged mild heat stress has been rather underestimated. However, the cellular response to mild heat stress is likely to be more important in a physiological sense than that to severe heat stress because the body temperature of homeothermic animals increases by only 1–2°C during febrile diseases. Here we provide information that mild heat stress does have some beneficial role in organisms via positively regulating cell proliferation and differentiation, and immune response in mammalian cells.Received 14 May 2004; received after revision 2 August 2004; accepted 16 August 2004     

电离辐射引发细胞凋亡的信号通路

电离辐射诱发细胞产生凋亡与细胞的辐射敏感性有关,而辐射的生物学效应则因其引发细胞凋亡的信号通路不同而有差异。辐射诱发凋亡作用过程至少包括SAPK／JNK信号通路及依赖于DNA损伤、依赖于胞质电离损伤和依赖于质膜损伤的四种信号通路。本文就辐射诱发细胞凋亡的信号传导途径进行简介。     

多参考信号的ICA方法及其在去除脑电伪差中应用

为消除脑电信号中的心电、眼电等伪差,在已有的不动点算法和带参考信号的独立分量分析算法的基础上,提出了一种多参考信号的独立分量分析方法.该方法通过计算各伪差在各路观测信号中的比重,去除伪差对观测信号的影响,从而得到较为纯净的脑电信号,所提方法相对于传统的fast ICA算法具有更小的计算量,并且不需要对分离的独立源进行人工干预,同时也是对ICA-R算法的一种扩展,解决了其只能提取单路源信号的缺点.仿真实验证明该方法更切合实际情况,而且能够更加有效地去除脑电信号中的多个伪差.