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.”
標簽： Time-Varying Channels
上傳時間： 2020-06-01
上傳用戶：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.
標簽： Cogeneration District Systems Energy and
上傳時間： 2020-06-07
上傳用戶：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.
標簽： Monitoring Protection Wide Area
上傳時間： 2020-06-07
上傳用戶：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.
標簽： Architectures NETWORKS SENSOR RFID AND
上傳時間： 2020-06-08
上傳用戶：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).
標簽： A_Software-Defined_GPS_and_Galile o_Receiver
上傳時間： 2020-06-09
上傳用戶：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 二叉樹子系統"); printf("\n\t\t*****************************************"); printf("\n\t\t 1---------建二叉樹 "); printf("\n\t\t 2---------先序遍歷 "); printf("\n\t\t 3---------中序遍歷 "); printf("\n\t\t 4---------后序遍歷 "); printf("\n\t\t 5---------求葉子數 "); printf("\n\t\t 6---------求結點數 "); printf("\n\t\t 7---------求樹深度 "); printf("\n\t\t 0---------返 回 "); printf("\n\t\t*****************************************"); printf("\n\t\t 請選擇菜單號 （0--7）"); scanf("%c",&ch2); getchar(); printf("\n"); switch(ch2) { case'1': printf("\n\t\t請按先序序列輸入二叉樹的結點:\n"); printf("\n\t\t說明：輸入結點（‘0’代表后繼結點為空）后按回車。\n"); printf("\n\t\t請輸入根結點:"); T=CreateTree(); printf("\n\t\t二叉樹成功建立！\n");break; case'2': printf("\n\t\t該二叉樹的先序遍歷序列為:"); Preorder(T);break; case'3': printf("\n\t\t該二叉樹的中序遍歷序列為:"); Inorder(T);break; case'4': printf("\n\t\t該二叉樹的后序遍歷序列為:"); Postorder(T);break; case'5': count=0;Leafnum(T); printf("\n\t\t該二叉樹有%d個葉子。\n",count);break; case'6': count=0;Nodenum(T); printf("\n\t\t該二叉樹總共有%d個結點。\n",count);break; case'7': printf("\n\t\t該樹的深度為:%d",TreeDepth(T)); break; case'0': ch1='n';break; default: printf("\n\t\t***請注意：輸入有誤！***"); } if(ch2!='0') { printf("\n\n\t\t按【Enter】鍵繼續，按任意鍵返回主菜單！\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請輸入%c結點的左子結點:",t->data); t->lchild=CreateTree(); printf("\n\t\t請輸入%c結點的右子結點:",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; } }
上傳時間： 2020-06-11
上傳用戶：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請輸入稀疏矩陣的行數，列數和非零元素個數（用逗號隔開）:"); scanf("%d,%d,%d",&A.cols,&A.terms); for(int n=0;n<=A.terms-1;n++) { printf("\n\t\t輸入非零元素值（格式：行號，列號，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對角線元素的和：:%d\n",p->v); else printf("\n\t\t對角線元素的和為：:0"); } int main() { int ch=1,choice; struct sparmatrix A; A.terms=0; while(ch) { printf("\n"); printf("\n\t\t 稀疏矩陣的三元組系統 "); printf("\n\t\t*********************************"); printf("\n\t\t 1------------創建 "); printf("\n\t\t 2------------顯示 "); printf("\n\t\t 3------------求對角線元素和"); printf("\n\t\t 4------------返回 "); printf("\n\t\t*********************************"); printf("\n\t\t請選擇菜單號（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輸入錯誤！請重新輸入！\n"); break; } if (choice==1||choice==2||choice==3) { printf("\n\t\t"); system("pause"); system("cls"); } else system("cls"); } }
上傳時間： 2020-06-11
上傳用戶：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; }
標簽： C++
上傳時間： 2020-06-30
上傳用戶：1274636550
--stdafx.h中沒有函數庫，只是定義了一些環境參數，使得編譯出來的程序能在32位的操作系統環境下運行。 windows和mfc的include文件都非常大，即使有一個快速的處理程序，編譯程序也要花費相當長的時間來完成工作。由于每個.cpp文件都包含相同的include文件，為每個.cpp文件都重復處理這些文件就顯得很傻了。 為避免這種浪費，appwizard和visualc++編譯程序一起進行工作，如下所示： --appwizard建立了文件stdafx.h，該文件包含了所有當前工程文件需要的mfcinclude文件。且這一文件可以隨被選擇的選項而變化。 --appwizard然后就建立stdafx.cpp。這個文件通常都是一樣的。 --然后appwizard就建立起工程文件，這樣第一個被編譯的文件就是stdafx.cpp。 --當visualc++編譯stdafx.cpp文件時，它將結果保存在一個名為stdafx.pch的文件里。(擴展名pch表示預編譯頭文件。) --當visualc++編譯隨后的每個.cpp文件時，它閱讀并使用它剛生成的.pch文件。visualc++不再分析windowsinclude文件，除非你又編輯了stdafx.cpp或stdafx.h。 在這個過程中你必須遵守以下規則： --你編寫的任何.cpp文件都必須首先包含stdafx.h。 --如果你有工程文件里的大多數.cpp文件需要.h文件，順便將它們加在stdafx.h(后部)上，然后預編譯stdafx.cpp。 --由于.pch文件具有大量的符號信息，它是你的工程文件里最大的文件。 如果你的磁盤空間有限，你就希望能將這個你從沒使用過的工程文件中的.pch文件刪除。執行程序時并不需要它們，且隨著工程文件的重新建立，它們也自動地重新建立。
標簽： stdafx
上傳時間： 2021-05-19
上傳用戶：1155
STM32F407VGT6精確脈沖控制步進電機源碼,采用STM32F407VGT6芯片，拋棄單脈沖輸出方式，直接使用普通PWM輸出方式精確輸出脈沖個數，每個脈沖都可以改變頻率和占空比。PWM+中斷，簡單粗暴。#include "sys.h"#include "delay.h"#include "pwm1.h"#include "pwm2.h"#include "pwm3.h"//注釋見pwm1.c文件extern int count2;int main(void){ delay_init(168); //初始化延時函數 TIM2_Init(1,167); TIM3_Init(1,167); TIM5_Init(1,167); // delay_ms(1000); TIM2_OUTPUT(); TIM3_OUTPUT(); TIM5_OUTPUT(); while(1) { //TIM2每次輸出完10個脈沖后間隔100ms再次輸出 if(count2 >= 10){ delay_ms(100); TIM2_OUTPUT(); } }
標簽： stm32f407vgt6 脈沖控制 步進電機
上傳時間： 2021-10-26
上傳用戶：xsr1983
