The Integration of CPS,CPSS, and ITS: A Focus on Data

Cyber-Physical System(CPS)and Cyber-Physical-Social System(CPSS)computing are now challenging existing research in many realms,including Intelligent Transportation Systems(ITS).In this survey,we highlight some advances in the coevolution of CPS,CPSS,and ITS,with an emphasis on traffic data.We first explain the hierarchical architecture of CPS-ITS in terms of five layers:perception,communication,computing,control,and application.Then,we analyze the characteristics of traffic data in CPS-ITS,and enumerate some new technologies for data operation and management.Two typical cases of CPS-ITS,vehicular-communication-based traffic control systems and smart parking systems,are illustrated to describe how CPS is changing our lives and influencing the development of future ITS.     

嵌入式系统发展综述

IT产业高度发达,嵌入式系统功不可没,以至于无处不见嵌入式系统。嵌入式系统家族庞大,涵盖内容广泛,涉及学科多样,了解其家族成员及发展历史,正确理解其概念体系及发展趋势,对于今后的“智慧地球”具有重大意义。总结了国内外的相关文献,概述了嵌入式系统的体系结构,分析了所面临的挑战,讨论了与相关技术的关系,最后展望了发展前景。     

基于AT89C52脉冲信号发生技术的研究与实现

在分析正弦脉宽调制技术原理基础上,提出一种脉冲信号发生技术新方法.系统采用单片机AT89C52与L298双极性正弦脉宽调制模块为核心,分别实现4种不同频率的SPWM脉冲序列输出.测试结果表明该方案正确有效,误差较小,具有实际应用意义.     

差分混沌键控(DCSK)通信系统估值误差分析

在具有去噪声模块的DCSK（differential chacs shift keying）通信系统中，存在三种导致估值误差的因素，这三种因素分别来源于DCSK信号本身、加性信道噪声和去噪声模块。经过对上述三种因素的分析，提出了一种新型的DCSK通信系统，该系统使用混沌多相序列（CPS）避免DCSK信号本身带来的误差，同时采用相空间量子化的方法降低加性信道噪声的干扰。仿真结果表明，虽然这种新型的DCSK通信系统因去噪声算法带来的误差而使其噪声特性略逊于FM－DCSK，但是在CPU运算时间及系统结构上，该系统比FM－DCSK复杂性降低，易于实现。     

主提升鼠笼式异步电动机变频改造

主提升鼠笼式异步电动机变频调速系统的改造,其中以产生SPWM的HEF4752为控制核心,实现了鼠笼式异步电动机变频调速的闭环控制。     

SPWM逆变器死区效应机理分析及数字仿真

将ＳＰＷＭ逆变器的死区分为控制死区和开关死区,并对死区效应的机理进行了详细的分析。运用解析方法、数字仿真方法和定性分析方法讨论了控制死区效应与逆变器输出基波电压、电压畸变率、基波电流、电流畸变率的关系和变化规律,并用实验结果验证了上述分析结论。本文对于深入研究和提高逆变器性能、优化控制策略等方面都是非常有用的。     

Temperature dependent dielectric relaxation spectroscopy of amyl acetate-xylene solutions – An approach to molecular and co-operative dynamics

Dielectric relaxation parameters of AMA-Xylene solutions have been investigated thoroughly to discern the associativeness as well as heterogeneous behavior among the hetero molecules in the solutions such that dielectric constant (ε_o) and relaxation time (τ) of solutions has been determined. Complex permittivity spectra (CPS) for Amyl Acetate (AMA)-Xylene solutions were measured in 10 MHz–50 GHz frequency range using Time domain reflectometry (TDR) technique. It is exciting to explore the cooperative nature and association between AMA-Xylene. With co-operative domains (CDs), dynamics in AMA-AMA and AMA-Xylene molecules have been explicated while Kirkwood validates CDs with diverse exchanges through bonding. The experimental values of ε_o are compared with theoretical values obtained from the molecular parameters suggested by the Luzar. Thermodynamic parameters for AMA-Xylene show positive values of Enthalpy and Entropy for all concentrations, indicating that the system is endothermic and less ordered. Gibbs free energy decreases with increase in volume fraction of amyl acetate (V_AMA).     

Metformin Inhibits the Urea Cycle and Reduces Putrescine Generation in Colorectal Cancer Cell Lines

The urea cycle (UC) removes the excess nitrogen and ammonia generated by nitrogen-containing compound composites or protein breakdown in the human body. Research has shown that changes in UC enzymes are not only related to tumorigenesis and tumor development but also associated with poor survival in hepatocellular, breast, and colorectal cancers (CRC), etc. Cytoplasmic ornithine, the intermediate product of the urea cycle, is a specific substrate for ornithine decarboxylase (ODC, also known as ODC1) for the production of putrescine and is required for tumor growth. Polyamines (spermidine, spermine, and their precursor putrescine) play central roles in more than half of the steps of colorectal tumorigenesis. Given the close connection between polyamines and cancer, the regulation of polyamine metabolic pathways has attracted attention regarding the mechanisms of action of chemical drugs used to prevent CRC, as the drug most widely used for treating type 2 diabetes (T2D), metformin (Met) exhibits antitumor activity against a variety of cancer cells, with a vaguely defined mechanism. In addition, the influence of metformin on the UC and putrescine generation in colorectal cancer has remained unclear. In our study, we investigated the effect of metformin on the UC and putrescine generation of CRC in vivo and in vitro and elucidated the underlying mechanisms. In nude mice bearing HCT116 tumor xenografts, the administration of metformin inhibited tumor growth without affecting body weight. In addition, metformin treatment increased the expression of monophosphate (AMP)-activated protein kinase (AMPK) and p53 in both HCT116 xenografts and colorectal cancer cell lines and decreased the expression of the urea cycle enzymes, including carbamoyl phosphate synthase 1 (CPS1), arginase 1 (ARG1), ornithine trans-carbamylase (OTC), and ODC. The putrescine levels in both HCT116 xenografts and HCT116 cells decreased after metformin treatment. These results demonstrate that metformin inhibited CRC cell proliferation via activating AMPK/p53 and that there was an association between metformin, urea cycle inhibition and a reduction in putrescine generation.     

基于SPWM数字驱动技术的电罗经复示器的研究

借鉴低速同步电机的驱动特点,提出了一种全数字式SPWM波数字细分驱动技术,将其应用到船舶电罗经复示器的电机控制系统中,实现了一种新型的全数字式步进电机控制系统.它以LF2407A DSP微处理器为控制器件,以专为两相/四相步进电机设计的L298N双全桥驱动芯片为功率驱动器件.     

基于并联逆变器的并联型功率因数校正技术研究

提出了并联于电源与负载之间的并联型功率因数校正技术,采用倍频载波相移SPWM技术的并联逆变器作为主电路结构,降低功率器件的电流等级,提高逆变器的等效开关频率.从电源电压和逆变器直流侧电容电压提取电源电流的指令电流的相位和幅值信息,采用电压外环PI调节电流内环P调节实现电源电流与电源电压同频同相,控制算法简单,鲁棒性好.进行了仿真和实验验证,带线性及非线性负载时功率因数达到0.99,谐波畸变率低,结果证明了并联型PFC的正确性和有效性.