Wireless communications has become a field of enormous scientific and economic interest. Recent success stories include 2G and 3G cellular voice and data services (e.g., GSM and UMTS), wireless local area networks (WiFi/IEEE 802.11x), wireless broadband access (WiMAX/IEEE 802.16x), and digital broadcast systems (DVB, DAB, DRM). On the physical layer side, traditional designs typically assume that the radio channel remains constant for the duration of a data block. However, researchers and system designers are increasingly shifting their attention to channels that may vary within a block. In addition to time dispersion caused by multipath propagation, these rapidly time-varying channels feature frequency dispersion resulting from the Doppler effect. They are, thus, often referred to as being “doubly dispersive.”
标签： Time-Varying Channels
上传时间： 2020-06-01
上传用户：shancjb
District energy (DE) systems use central heating and/or cooling facilities to provide heating and/or cooling services for communities. The advantages of district energy over conventional heating and cooling include improved efficiency, reliability and safety, reduced environmental impact, and for many situations better economics. DE systems can be particularly beneficial when integrated with cogeneration plants for electricity and heat, i.e., with combined heat and power (CHP) plants. One of the main impediments to increased use of cogeneration-based district energy is a lack of understanding of the behavior of integrated forms of such systems. This book is aimed at providing information on district energy and cogeneration tech- nologies, as well as systems that combine them.
标签： Cogeneration District Systems Energy and
上传时间： 2020-06-07
上传用户：shancjb
Today, electric power transmission systems should face many demanding chal- lenges, which include balancing between reliability, economics, environmental, and other social objectives to optimize the grid assets and satisfy the growing electrical demand. Moreover, the operational environment of transmission systems is becoming increasingly rigorous due to continually evolving functions of interconnected power networks from operation jurisdiction to control responsibly – coupled with the rising demand and expectation for reliability.
标签： Monitoring Protection Wide Area
上传时间： 2020-06-07
上传用户：shancjb
Radio frequency identification (RFID) technology is witnessing a recent explosion of development in both industry and academia. A number of applications include supply chain management, electronic payments, RFID passports, environmental monitoring and control, office access control, intelligent labels, target detection and tracking, port management, food production control, animal identification, and so on. RFID is also an indispensable foundation to realize the pervasive computing paradigm—“Internet of things.” It is strongly believed that many more scenarios will be identified when the principles of RFID are thoroughly understood, cheap components available, and when RFID security is guaranteed.
标签： Architectures NETWORKS SENSOR RFID AND
上传时间： 2020-06-08
上传用户：shancjb
Software-defined radios (SDRs) have been around for more than a decade. The first complete Global Positioning System (GPS) implementation was described by Dennis Akos in 1997. Since then several research groups have presented their contributions. We therefore find it timely to publish an up-to-date text on the sub- ject and at the same time include Galileo, the forthcoming European satellite- based navigation system. Both GPS and Galileo belong to the category of Global Navigation Satellite Systems (GNSS).
标签： A_Software-Defined_GPS_and_Galile o_Receiver
上传时间： 2020-06-09
上传用户：shancjb
#include<stdio.h> #define TREEMAX 100 typedef struct BT { char data; BT *lchild; BT *rchild; }BT; BT *CreateTree(); void Preorder(BT *T); void Postorder(BT *T); void Inorder(BT *T); void Leafnum(BT *T); void Nodenum(BT *T); int TreeDepth(BT *T); int count=0; void main() { BT *T=NULL; char ch1,ch2,a; ch1='y'; while(ch1=='y'||ch1=='y') { printf("\n"); printf("\n\t\t 二叉树子系统"); printf("\n\t\t*****************************************"); printf("\n\t\t 1---------建二叉树 "); printf("\n\t\t 2---------先序遍历 "); printf("\n\t\t 3---------中序遍历 "); printf("\n\t\t 4---------后序遍历 "); printf("\n\t\t 5---------求叶子数 "); printf("\n\t\t 6---------求结点数 "); printf("\n\t\t 7---------求树深度 "); printf("\n\t\t 0---------返 回 "); printf("\n\t\t*****************************************"); printf("\n\t\t 请选择菜单号 （0--7）"); scanf("%c",&ch2); getchar(); printf("\n"); switch(ch2) { case'1': printf("\n\t\t请按先序序列输入二叉树的结点:\n"); printf("\n\t\t说明：输入结点（‘0’代表后继结点为空）后按回车。\n"); printf("\n\t\t请输入根结点:"); T=CreateTree(); printf("\n\t\t二叉树成功建立！\n");break; case'2': printf("\n\t\t该二叉树的先序遍历序列为:"); Preorder(T);break; case'3': printf("\n\t\t该二叉树的中序遍历序列为:"); Inorder(T);break; case'4': printf("\n\t\t该二叉树的后序遍历序列为:"); Postorder(T);break; case'5': count=0;Leafnum(T); printf("\n\t\t该二叉树有%d个叶子。\n",count);break; case'6': count=0;Nodenum(T); printf("\n\t\t该二叉树总共有%d个结点。\n",count);break; case'7': printf("\n\t\t该树的深度为:%d",TreeDepth(T)); break; case'0': ch1='n';break; default: printf("\n\t\t***请注意：输入有误！***"); } if(ch2!='0') { printf("\n\n\t\t按【Enter】键继续，按任意键返回主菜单！\n"); a=getchar(); if(a!='\xA') { getchar(); ch1='n'; } } } } BT *CreateTree() { BT *t; char x; scanf("%c",&x); getchar(); if(x=='0') t=NULL; else { t=new BT; t->data=x; printf("\n\t\t请输入%c结点的左子结点:",t->data); t->lchild=CreateTree(); printf("\n\t\t请输入%c结点的右子结点:",t->data); t->rchild=CreateTree(); } return t; } void Preorder(BT *T) { if(T) { printf("%3c",T->data); Preorder(T->lchild); Preorder(T->rchild); } } void Inorder(BT *T) { if(T) { Inorder(T->lchild); printf("%3c",T->data); Inorder(T->rchild); } } void Postorder(BT *T) { if(T) { Postorder(T->lchild); Postorder(T->rchild); printf("%3c",T->data); } } void Leafnum(BT *T) { if(T) { if(T->lchild==NULL&&T->rchild==NULL) count++; Leafnum(T->lchild); Leafnum(T->rchild); } } void Nodenum(BT *T) { if(T) { count++; Nodenum(T->lchild); Nodenum(T->rchild); } } int TreeDepth(BT *T) { int ldep,rdep; if(T==NULL) return 0; else { ldep=TreeDepth(T->lchild); rdep=TreeDepth(T->rchild); if(ldep>rdep) return ldep+1; else return rdep+1; } }
上传时间： 2020-06-11
上传用户：ccccy
#include <stdio.h> #include <stdlib.h> #define SMAX 100 typedef struct SPNode { int i,j,v; }SPNode; struct sparmatrix { int rows,cols,terms; SPNode data [SMAX]; }; sparmatrix CreateSparmatrix() { sparmatrix A; printf("\n\t\t请输入稀疏矩阵的行数，列数和非零元素个数（用逗号隔开）:"); scanf("%d,%d,%d",&A.cols,&A.terms); for(int n=0;n<=A.terms-1;n++) { printf("\n\t\t输入非零元素值（格式：行号，列号，值）:"); scanf("%d,%d,%d",&A.data[n].i,&A.data[n].j,&A.data[n].v); } return A; } void ShowSparmatrix(sparmatrix A) { int k; printf("\n\t\t"); for(int x=0;x<=A.rows-1;x++) { for(int y=0;y<=A.cols-1;y++) { k=0; for(int n=0;n<=A.terms-1;n++) { if((A.data[n].i-1==x)&&(A.data[n].j-1==y)) { printf("%8d",A.data[n].v); k=1; } } if(k==0) printf("%8d",k); } printf("\n\t\t"); } } void sumsparmatrix(sparmatrix A) { SPNode *p; p=(SPNode*)malloc(sizeof(SPNode)); p->v=0; int k; k=0; printf("\n\t\t"); for(int x=0;x<=A.rows-1;x++) { for(int y=0;y<=A.cols-1;y++) { for(int n=0;n<=A.terms;n++) { if((A.data[n].i==x)&&(A.data[n].j==y)&&(x==y)) { p->v=p->v+A.data[n].v; k=1; } } } printf("\n\t\t"); } if(k==1) printf("\n\t\t对角线元素的和：:%d\n",p->v); else printf("\n\t\t对角线元素的和为：:0"); } int main() { int ch=1,choice; struct sparmatrix A; A.terms=0; while(ch) { printf("\n"); printf("\n\t\t 稀疏矩阵的三元组系统 "); printf("\n\t\t*********************************"); printf("\n\t\t 1------------创建 "); printf("\n\t\t 2------------显示 "); printf("\n\t\t 3------------求对角线元素和"); printf("\n\t\t 4------------返回 "); printf("\n\t\t*********************************"); printf("\n\t\t请选择菜单号（0-3）:"); scanf("%d",&choice); switch(choice) { case 1: A=CreateSparmatrix(); break; case 2: ShowSparmatrix(A); break; case 3: SumSparmatrix(A); break; default: system("cls"); printf("\n\t\t输入错误！请重新输入！\n"); break; } if (choice==1||choice==2||choice==3) { printf("\n\t\t"); system("pause"); system("cls"); } else system("cls"); } }
上传时间： 2020-06-11
上传用户：ccccy
#include<iostream> using namespace std; int s=0; int prime(int x){ int i,p=1; for(i=2;i<=x/2;i++){ if(x%i==0){ p=0; break; } } if(p!=0){ cout<<x<< " "; s++; } } int main(){ for (int k=5;k<=100;k++){ prime(k); if(s%5==0) cout<<'\n'; } return 0; }
标签： C++
上传时间： 2020-06-30
上传用户：1274636550
--stdafx.h中没有函数库，只是定义了一些环境参数，使得编译出来的程序能在32位的操作系统环境下运行。 windows和mfc的include文件都非常大，即使有一个快速的处理程序，编译程序也要花费相当长的时间来完成工作。由于每个.cpp文件都包含相同的include文件，为每个.cpp文件都重复处理这些文件就显得很傻了。 为避免这种浪费，appwizard和visualc++编译程序一起进行工作，如下所示： --appwizard建立了文件stdafx.h，该文件包含了所有当前工程文件需要的mfcinclude文件。且这一文件可以随被选择的选项而变化。 --appwizard然后就建立stdafx.cpp。这个文件通常都是一样的。 --然后appwizard就建立起工程文件，这样第一个被编译的文件就是stdafx.cpp。 --当visualc++编译stdafx.cpp文件时，它将结果保存在一个名为stdafx.pch的文件里。(扩展名pch表示预编译头文件。) --当visualc++编译随后的每个.cpp文件时，它阅读并使用它刚生成的.pch文件。visualc++不再分析windowsinclude文件，除非你又编辑了stdafx.cpp或stdafx.h。 在这个过程中你必须遵守以下规则： --你编写的任何.cpp文件都必须首先包含stdafx.h。 --如果你有工程文件里的大多数.cpp文件需要.h文件，顺便将它们加在stdafx.h(后部)上，然后预编译stdafx.cpp。 --由于.pch文件具有大量的符号信息，它是你的工程文件里最大的文件。 如果你的磁盘空间有限，你就希望能将这个你从没使用过的工程文件中的.pch文件删除。执行程序时并不需要它们，且随着工程文件的重新建立，它们也自动地重新建立。
标签： stdafx
上传时间： 2021-05-19
上传用户：1155
STM32F407VGT6精确脉冲控制步进电机源码,采用STM32F407VGT6芯片，抛弃单脉冲输出方式，直接使用普通PWM输出方式精确输出脉冲个数，每个脉冲都可以改变频率和占空比。PWM+中断，简单粗暴。#include "sys.h"#include "delay.h"#include "pwm1.h"#include "pwm2.h"#include "pwm3.h"//注释见pwm1.c文件extern int count2;int main(void){ delay_init(168); //初始化延时函数 TIM2_Init(1,167); TIM3_Init(1,167); TIM5_Init(1,167); // delay_ms(1000); TIM2_OUTPUT(); TIM3_OUTPUT(); TIM5_OUTPUT(); while(1) { //TIM2每次输出完10个脉冲后间隔100ms再次输出 if(count2 >= 10){ delay_ms(100); TIM2_OUTPUT(); } }
标签： stm32f407vgt6 脉冲控制 步进电机
上传时间： 2021-10-26
上传用户：xsr1983
