For all people with power problems using Ubuntu 14.04 try downgrading your Linux kernel to Long term supported version
either 3.10 or 3.12
PS: it worked for me and will work for most of the people as 3.12 kernel is stable

 firstly download the 3 deb files which suit ur system architecture
if for 32 bit =>i386
for 64 bit =>amd64
go for files which have generic written
http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12.20-trusty/

Go to the downloaded folder

then run this

sudo dpkg -i linux-headers-3.12.20* linux-image-3.12.20* .deb

And then remove the 3.13 default kernel

sudo apt-get remove linux-headers-3.13.0* linux-image-3.13.*
And ur through

If possible change the URI for Kernel updates in Software Center.

Install power monitoring tools like Powertop.

sudo apt-get install powertop

In powertop go to turnables tab and toggle every row from bad to good

also install pm-utils

sudo apt-get install pm-utils

sudo pm-powersave true

this puts ur pc on power save mode

To implement SEMAPHORE in C

 /*
To implement SEMAPHORE in C

*/
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/sem.h>
#include<stdio.h>

int main()
{
        int semid,pid,val,i,withdraw;
        struct sembuf sop;
        FILE *fp;
        int balance;
        semid=semget(0x20,1,IPC_CREAT|0666);
        semctl(semid,0,SETVAL,1);
        sop.sem_num=0;
        sop.sem_op=-1;
        sop.sem_flg=SEM_UNDO;
        pid=fork();
        if(pid==0)
        {
                printf("Child Before Sem Operation\n");
                semop(semid,&sop,1);
                printf("Child is in Critical Section\n");
                fp = fopen("data.txt","r+");
                fscanf(fp,"%d",&balance);
                printf("Enter the Amount to be Withdrawn: ");
                scanf(" %d",&withdraw);
                rewind(fp);
                balance = balance - withdraw;
                fprintf(fp,"%d",balance);
                fclose(fp);
                sleep(2);
                printf("\nBalance = %d\n",balance);
                printf("Child Outside Critical Section\n");
        }
        else
        {
                printf("Parent Before Sem Operation\n");
                semop(semid,&sop,1);
                printf("Parent is in Critical Section\n");
                sleep(2);
                fp = fopen("data.txt","r+");
                fscanf(fp,"%d",&balance);
                printf("\nBalance = %d\n",balance);
                printf("Enter the Amount to be Withdrawn: ");
                scanf(" %d",&withdraw);
                rewind(fp);
                balance = balance - withdraw;
                fprintf(fp,"%d",balance);
                fclose(fp);
                sleep(2);
                printf("\nBalance = %d\n",balance);
                printf("Parent Outside Critical Section\n");
        }
        return 0;
}

/* Output:
Child Before Sem Operation
Child is in Critical Section
Parent Before Sem Operation
Enter the Amount to be Withdrawn: 10

Balance = 850
Child Outside Critical Section
Parent is in Critical Section

Balance = 850
Enter the Amount to be Withdrawn: 50

Balance = 800
Parent Outside Critical Section
*/

To Implement Inter Process Communication using Pipes

/*
To Implement Inter Process Communication using Pipes
*/

#include<stdio.h>
#include<unistd.h>
#include<string.h>

int main()
{
        int fd[2],n,status;
        char buff[100];
        pipe(fd);
        if(pipe (fd)<0)
        {
                printf("Cannot create a pipe.....");
                exit(0);
        }

        else
        {
                switch(fork())
                {
                        case -1:
                                printf("\nFork error...");
                                exit(0);
 
                        case 0:
                                //child process read data from buffer

                                printf("\nRunning child process...");
                                printf("\nBefore read is performed...");
                                read(fd[0],buff,100);
                                printf("\nThe data read from the buffer is:\t %s",buff);
                                break;

                        default:
                                //parent process writes to buffer

                                printf("\nRunning parent process...\n");
                                printf("\nWriting...\n");
                                write(fd[1],"Welcome to HOME....",60);
                                wait(&status);
                                printf("\nWriting is over...\n");
                                break;
                }
        }
    return(0);
}



/*
Output:
Running child process...

Running parent process...

Writing...
Before read is performed...
The data read from the buffer is:        Welcome to HOME....
Writing is over...
*/

IMPLEMENTATATION OF INODE USING C.

/*
TITLE:IMPLEMENTATATION OF INODE USING C.

*/

#include<sys/types.h>
#include<ustat.h>
#include<stdio.h>
#include<sys/dir.h>

main(argc,argv)
int argc;
char *argv[];
{
  FILE *fp;
  struct direct dir;
  fp=fopen(argv[1],"r");
  printf("\n Directory listing of %s\n",argv[1]);
  while(fread(&dir,sizeof(dir),1,fp)!=EOF)
  {
     if(dir.d_ino==0)
         continue;
          printf("inode number:%d of file:%s\n",dir.d_ino,dir.d_name);
  }
   fclose(fp);
   exit(0);
}

To Study the File-Handling

/*
To Study the File-Handling
*/


#include<stdio.h>
#include<fcntl.h>
#include<error.h>
#include<string.h>
#include<sys/wait.h>

int fd;
char name1[100];
void createfile(char *name)
{
printf("\n Enter name of file \n");
scanf("%s",name);
fd=open(name,O_CREAT|O_EXCL,0760);
if(fd==-1)
{
perror("\n ERROR!!!\n");
exit(1);
}

else
{
printf("\nfile created");
close(fd);
}
}


void copy()
{
char ch;
int n;
char name1[100], name2[100];
int fd1, fd2;
printf("\n Enter name of file to copy");
scanf("%s",name1);
fd1=open(name1,O_RDWR|O_APPEND,0760);
printf("\nEnter name of file to be copied into");
scanf("%s",name2);
fd2=open(name2,O_CREAT|O_EXCL|O_RDWR|O_APPEND,0761);
if(fd1==-1)
{
perror("\n ERROR!!!\n");
exit(1);
}
if(fd2==-1)
{
perror("\n ERROR!!!\n");
exit(1);
}


while(read(fd1,&ch,1)>0);
{
write(fd2,&ch,1);
}


printf("\n copied");
close(fd1);
close(fd2);
}
void writeandread()
{
char ch;
int n;
char name2[100], buff[100], buff1[100];
int fd1;
printf("\n Enter name of file to write");
scanf("%s",name1);
fd1=open(name1,O_RDWR|O_APPEND,0760);
/*printf("\nEnter name of file");
scanf("%s",name2);
fd2=open(name2,O_CREAT|O_EXCL|O_RDWR|O_APPEND,0761);
*/
if(fd1==-1)
{
perror("\n ERROR!!!\n");
exit(1);
}

else
{
printf("\nEnter to write");
scanf("%s",buff);
write(fd1,buff,strlen(buff));
printf("\nwrite succesfull");
lseek(fd1,0,SEEK_SET);
read(fd1,buff1,strlen(buff));
printf("\nfile contains: %s\n",buff1);
}
printf("\nexiting");
close(fd1);

}

int main()

{
char name[100];
createfile(name);
        writeandread();
copy();
return 0;
}

/*
OUTPUT:
bash-3.00$ cc file.c
bash-3.00$ ./a.out

Enter name of file a1

file created
 Enter name of file to write a1

Enter to write hi

write succesfull
file contains: hij

exiting
 Enter name of file to copy a1

Enter name of file to be copied into a2

 copiedbash-3.00$ ./a.out
*/

IMPLEMENTATATION OF PARENT CHILD PROCESS USING C.

/*

TITLE: IMPLEMENTATATION OF PARENT CHILD PROCESS USING C.
*/




#include<stdio.h>
#include<sys/wait.h>

int main()
{
      int pid,status,n1,n2,sum;
      printf("\n parent(user) program is in execution");
      pid=fork();
      printf("\n spanning the child process");
      if(pid==0)
      {
           printf("\n Child is executing :\n");
           printf("\n Enter two no.:\n");
           scanf("%d  %d",&n1,&n2);
           sum=n1+n2;
           printf("the sum is: %d\n",sum);
           printf(" pid of child is: %d\n",getpid());
           printf("pid of parent is: %d\n",getppid());
           printf("\n exiting child \n");

      }
    else
     {
       wait(&status);
              printf("\n parent is executing: \n");
           printf("\n pid of parent is :%d\n",getpid());
           printf("\n pid of parent's parent is: %d\n ",getppid());

         
           printf("\n exiting parent \n");
     }
   return 0;
}
/*
 parent(user) program is in execution
 spanning the child process
 Child is executing :

 Enter two no.:
 parent(user) program is in execution
20
14
the sum is: 34
 pid of child is: 4874
pid of parent is: 4873

 exiting child
 spanning the child process
 parent is executing:

 pid of parent is :4873

 pid of parent's parent is: 4857

 exiting parent
*/

TO IMPLEMENT SHORTEST JOB FIRST IN JAVA

/*
TOPIC : TO IMPLEMENT SHORTEST JOB FIRST IN JAVA
*/

import java.util.*;
public class SJF
{
  public static void main(String args[])throws Exception{
Scanner s=new Scanner(System.in);
int n=0;
System.out.println("Enter no of processes :");
n=s.nextInt();
Process[] p=new Process[n];
for(int i=0;i<n;i++)
{
   p[i]=new Process();
}
for(int i=0;i<n;i++)
{
  System.out.println("PROCESS ID :");
p[i].id=s.nextInt();
System.out.println("ARRIVAL TIME :");
p[i].atime=s.nextInt();
System.out.println("Burst TIME :");
p[i].btime=s.nextInt();
}
for(int i=0;i<n-1;i++)
{
   for(int j=0;j<n-1;j++)
{
   if(p[j].btime>p[j+1].btime)
{
  Process t=p[j];
   p[j]=p[j+1];
   p[j+1]=t;
}
}
}
System.out.println("Process id\tArrival time\tBurst time");
System.out.println("...............................");
for(int i=0;i<n;i++)
{
   System.out.println(""+p[i].id+"\t\t"+p[i].atime+"\t\t"+p[i].btime);
}
}
}
class Process {
  int id,btime,atime;
}
/* OUTPUT
Enter no of processes :
2
PROCESS ID :
99
ARRIVAL TIME :
20
Burst TIME :
12
PROCESS ID :
10
ARRIVAL TIME :
21
Burst TIME :
32
Process id      Arrival time    Burst time
...............................
99              20              12
10              21              32
*/

TO IMPLEMENT ROUND ROBIN TIME SLICING IN JAVA

/*
TO IMPLEMENT ROUND ROBIN TIME SLICING IN JAVA
*/

import java.util.*;
public class RR
{
public static void main(String arg[])throws Exception
{
Scanner s=new Scanner(System.in);
int n,quan,tat;
System.out.println("Enter no of processes:");
n=s.nextInt();
System.out.println("enter time quantum:");
quan=s.nextInt();
Process p[]=new Process[n];
for(int i=0;i<n;i++)
{
p[i]=new Process();
}
for(int i=0;i<n;i++)
{
System.out.println("PROCESS ID:");
p[i].id=s.nextInt();
System.out.println("ARRIVAL TIME:");
p[i].atime=s.nextInt();
System.out.println("Burst time:");
p[i].btime=s.nextInt();
}
for(int i=0;i<n-1;i++)
{
for(int j=0;j<n-1;j++)
{
if(p[j].atime>p[j+1].atime)
{
Process t=p[j];
p[j]=p[j+1];
p[j+1]=t;
}
}
}
System.out.println("Process id\tArrival time\tBurst time");
System.out.println("...................................");
tat=0;
boolean flag=true;
int pass=0;
while(pass!=2)
{
for(int i=0;i<n;i++)
{
if(flag==true)
{
p[i].rbt=p[i].btime;
p[i].rbt=p[i].rbt-quan;
}
else
{
p[i].rbt=p[i].rbt-quan;
}
if(p[i].rbt>-4)
{
if(p[i].rbt<0)
p[i].rbt=0;
System.out.println(""+p[i].id+"\t\t"+p[i].atime+"\t\t"+p[i].btime+"\t\t"+p[i].rbt);
}
}
flag=false;
pass++;
}
}
}
class Process
{
int id,btime,atime,rbt;
Process()
{
id=0;
atime=0;
btime=0;
rbt=0;
}
}

/* OUTPUT
Enter no of processes:
2
enter time quantum:
12
PROCESS ID:
32
ARRIVAL TIME:
21
Burst time:
125
PROCESS ID:
45
ARRIVAL TIME:
12
Burst time:
12
Process id      Arrival time    Burst time
...................................
45              12              12              0
32              21              125             113
32              21              125             101
*/

TO IMPLEMENT PROCESS PRIORITY IN JAVA

/*

Title   :TO IMPLEMENT PROCESS PRIORITY IN JAVA
*/

import java.util.*;
public class Priority
{
  public static void main(String args[])throws Exception{
Scanner s=new Scanner(System.in);
int n=0;
System.out.println("Enter no of processes :");
n=s.nextInt();
Process[] p=new Process[n];
for(int i=0;i<n;i++)
{
   p[i]=new Process();
}
for(int i=0;i<n;i++)
{
  System.out.println("PROCESS ID :");
p[i].id=s.nextInt();
System.out.println("ARRIVAL TIME :");
p[i].atime=s.nextInt();
System.out.println("Burst TIME :");
p[i].btime=s.nextInt();
System.out.println("Priority :");
p[i].prior=s.nextInt();
}
for(int i=0;i<n-1;i++)
{
   for(int j=0;j<n-1;j++)
{
   if(p[j].prior>p[j+1].prior)
{
  Process t=p[j];
   p[j]=p[j+1];
   p[j+1]=t;
}
}
}
System.out.println("Process id\tArrival time\tBurst time\tPriority");
System.out.println("...............................");
for(int i=0;i<n;i++)
{
   System.out.println(""+p[i].id+"\t\t"+p[i].atime+"\t\t"+p[i].btime+"\t\tp"+p[i].prior);
}
}
}
class Process {
  int id,btime,atime,prior;
}

/*OUTPUT
Enter no of processes :
2
PROCESS ID :
12
ARRIVAL TIME :
14
Burst TIME :
45
Priority :
1
PROCESS ID :
21
ARRIVAL TIME :
23
Burst TIME :
45
Priority :
2
Process id      Arrival time    Burst time      Priority
...............................
12              14              45              p1
21              23              45              p2
*/

TO IMPLEMENT MULTITHREADING AND OBSERVE TIMESLICING

/*

TO IMPLEMENT MULTITHREADING AND OBSERVE TIMESLICING
*/
import java.util.*;
class q extends Thread
{
public void run()
{
try{
for(int i=0;i<12;i++)
{
System.out.println("12"+"x"+i+"="+(i*12));
Thread.sleep(2000);
}
}catch(Exception e){}
}
}
class p extends Thread
{
public void run()
{
try{
for(int i=0;i<12;i++)
{
System.out.println("10"+"x"+i+"="+(i*10));
Thread.sleep(2000);
}
}catch(Exception e){}
}
}
class multi
{
public static void main(String args[]) throws Exception
{
p a=new p();
q b=new q();
a.start();
b.start();
//THIS PROGRAM IS CODED BY TG;
}
}
/*
OUTPUT
 javac multi.java
bash-4.1$ java multi
10x0=0
12x0=0
10x1=10
12x1=12
10x2=20
12x2=24
10x3=30
12x3=36
10x4=40
12x4=48
10x5=50
12x5=60
10x6=60
12x6=72
10x7=70
12x7=84
10x8=80
12x8=96
10x9=90
12x9=108
10x10=100
12x10=120
10x11=110
12x11=132
*/

TO IMPLEMENT LRU IN JAVA

/*
TO IMPLEMENT LRU IN JAVA

*/
import java.util.*;

class Queue
{
int q[]=new int[3];
int f=0;
int count=0;
 void insert(int d)
{

if(f!=3)
{

if(find(d) && count==2)
{System.out.print("\nHIT");f++;}
else
q[f++]=d;
}

else
{
f=0;

       if(find(d) && count==2)
{System.out.print("\nHIT");f++;}
else
q[f++]=d;
}
System.out.print("\nTop:"+f);
}

 boolean find(int d)
  {
if(count==3) count=2;
for(int i=0;i<=count;i++)
{
if(d==q[i] && count>=2)
return true;


}


return  false;
}
 void traverse()
{
        if(count==3) count=2;
for(int i=0;i<=count;i++)
{

System.out.print("\n"+q[i]);
}
if(count<3) count++;
System.out.println();
}

 }


class LRU
{
public static void main(String args[])
{
Scanner src=new Scanner(System.in);

                int a[]={7,0,1,2,0,3,0,4,2,3,0,3,2,1};
Queue q=new Queue();
for(int i=0;i<14;i++)
{
q.insert(a[i]);
q.traverse();
}
}
}

TO IMPLEMENT FIFO-First In First Out

/*
TO IMPLEMENT FIFO-First In First Out
*/
import java.util.*;

class Queue
{
int q[]=new int[3];
int f=0;
int count=0;
 void insert(int d)
{
if(f!=3)
{

if(q[f]==d && count==2)
{System.out.print("\nHIT");}
else
q[f++]=d;
}

else
{
f=0;

       if(q[f]==d && count==2)
{System.out.print("\nHIT");}
else
q[f++]=d;
}
}


 void traverse()
{
for(int i=0;i<=count;i++)
{

System.out.print("\n"+q[i]);
}
if(count<2) count++;
System.out.println();
}

 }


class FIFO
{
public static void main(String args[])
{
Scanner src=new Scanner(System.in);

                int a[]={7,0,1,2,0,3,0,4,2,3,0,3,2,1};
Queue q=new Queue();
for(int i=0;i<14;i++)
{
q.insert(a[i]);
q.traverse();
}
}
}

/*OUTPUT

bash-3.00$ java FIFO

7

7
0

7
0
1

2
0
1

HIT
2
0
1

2
3
1

2
3
0

4
3
0

4
2
0

4
2
3

0
2
3

0
3
3

0
3
2

1
3
2

*/

TO IMPLEMENT First Come First Service

/*
TO IMPLEMENT First Come First Service

*/
import java.util.*;
public class FCFS
{
  public static void main(String args[])throws Exception{
Scanner s=new Scanner(System.in);
int n=0;
System.out.print("Enter no of processes :");
n=s.nextInt();
Process[] p=new Process[n];
for(int i=0;i<n;i++)
{
   p[i]=new Process();
}
for(int i=0;i<n;i++)
{
  System.out.print("PROCESS ID :");
p[i].id=s.nextInt();
System.out.println("ARRIVAL TIME :"+i);
p[i].atime=i;
System.out.print("Burst TIME :");
p[i].btime=s.nextInt();
}
/*for(int i=0;i<n-1;i++)
{
   for(int j=0;j<n-1;j++)
{
   if(p[j].atime>p[j+1].atime)
{
  Process t=p[j];
   p[j]=p[j+1];
   p[j+1]=t;
}
}
}
System.out.println("Process id\tArrival time\tBurst time");
System.out.println("...............................");
for(int i=0;i<n;i++)
{
   System.out.println(""+p[i].id+"\t\t"+p[i].atime+"\t\t"+p[i].btime);
}
*/
System.out.print("\nStarting to execute process");
for(int i=0;i<n;i++)
{
System.out.print("\nProcess "+p[i].id+" under execution");
Thread.sleep((p[i].btime)*1000);
System.out.println("\nProcess "+p[i].id+" executed");
}

}
}
class Process {
  int id,btime,atime;
}
/*OUTPUT  
bash-3.00$ java FCFS
bash-3.00$ java FCFS
Enter no of processes :3
PROCESS ID :1
ARRIVAL TIME :0
Burst TIME :7
PROCESS ID :2
ARRIVAL TIME :1
Burst TIME :1
PROCESS ID :3
ARRIVAL TIME :2
Burst TIME :3

Starting to execute process
Process 1 under execution
Process 1 executed

Process 2 under execution
Process 2 executed

Process 3 under execution
Process 3 executed

*/