### Number Conversion

Number conversion is the fundamental operation of any digital systems.

There are different bases like base2, base8, base10 and base 16

 Base – 10 Base 2 (Binary) Base 8 (Octal) Base 16 (Hexadecimal) 0 0000 00 0 1 0001 01 1 2 0010 02 2 3 0011 03 3 4 0100 04 4 5 0101 05 5 6 0110 06 6 7 0111 07 7 8 1000 10 8 9 1001 11 9 10 1010 12 A 11 1011 13 B 12 1100 14 C 13 1101 15 D 14 1110 16 E 15 1111 17 F

The above table shows the various base systems.

Converting between one base to another base is of importance.  Usually all the numbering systems of day to day life is done using Base 10 or Decimal system. So it is necessary to convert

• Other Base to Decimal
• Decimal to other base

Any number represented as

 anan-1an-2an-3…..a1a0 . a-1a-2……..a-n

We will see one by one

Decimal to Binary (Base 10 to Base 2)

(19.456)10 – (?.?)2

In the above, the number 19.456 has to be converted to binary or base2 which will have only 0s and 1s.

First we will take 19

 Division Quotient Remainder Remarks 19/2 9 1 a0=1 9/2 4 1 a1=1 4/2 2 0 a2=0 2/2 1 0 a3=0 1/2 0 1 a4=1

so the conversion is 10011

Secondly we will take (0.456)10

 Multiplication Whole number decimal Remarks 0.456 * 2 0 0.912 a-1=0 0.912 * 2 1 0.824 a-2=1 0.824 * 2 1 0.648 a-3=1 0.648 * 2 1 0.296 a-4=1

Therefore (0.456)10 is (0.0111)2

Finally (19.456)10 = (10011.0111)2

Binary (Base 2) to Decimal (Base 10) Conversion

(11110.0111)2 = (?.?)10

Let us take the whole portion 11110

 1 1 1 1 0 . 0 1 1 1 a4 a3 a2 a1 a0 . a-1 a-2 a-3 a-4 1 * 24 1 * 23 1 * 22 1 * 21 0 * 20 . 0 * 2-1 1 * 2-2 1 * 2-3 1 * 2-4 16 8 4 2 0 . 0.5 0.25 0.125 0.0625

Total is 30.9375

Decimal to Octal (Base 10 to Base 8)

(19.456)10 – (?.?)8

In the above, the number 19.456 has to be converted to binary or base2 which will have only 0s and 1s.

First we will take 19

 Division Quotient Remainder Remarks 19/8 2 3 a0=3 2/8 0 2 a1=2

so the conversion is 23

Secondly we will take (0.456)10

 Multiplication Whole number decimal Remarks 0.456 * 8 3 0.648 a-1=3 0.648 * 8 5 0.184 a-2=5 0.824 * 8 1 0.472 a-3=1

Therefore (0.456)10 is (0.351)8

Finally (19.456)10 = (23.351)8

Octal (Base 8) to Decimal (Base 10) Conversion

(337.64)8 = (?.?)10

Let us take the whole portion 11110

 3 3 7 . 6 4 a2 a1 a0 . a-1 a-2 3 * 82 3 * 81 7 * 80 . 6 * 8-1 4 * 8-2 192 24 7 . 0.75 0.0625

Total is 267.8125

Decimal to Hexadecimal (Base 10 to Base 16)

(19.456)10 – (?.?)16

In the above, the number 19.456 has to be converted to binary or base2 which will have only 0s and 1s.

First we will take 19

 Division Quotient Remainder Remarks 19/16 1 3 a0=3 1/16 0 1 a1=1

so the conversion is (13)16

Secondly we will take (0.456)10

 Multiplication Whole number decimal Remarks 0.456 * 16 7 0.296 a-1=7 0.296 * 16 4 0.736 a-2=4 0.736 * 16 B 0.776 a-3=B

Therefore (0.456)10 is (0.74B)16

Finally (19.456)10 = (13.74B)16

Octal (Base 8) to Decimal (Base 10) Conversion

(1AB.62)16 = (?.?)10

Let us take the whole portion 11110

 1 A B . 6 2 a2 a1 a0 . a-1 a-2 1 * 162 10 * 161 11 * 160 . 6 * 16-1 2 * 16-2 256 160 11 . 0.375 0.007

Total is (427.382)10

### Implementing a new system call in Kernel version 2.6.32

A system call is used by application or user programs to request service from the operating systems. Since the user programs does not have direct access to the kernel whereas the OS has the direct access. OS can access the hardware through system calls only.The following files has to be modified for implementing a system call/usr/src/linux-2.6.32.5/arch/x86/kernel/syscall_table_32.S/usr/src/linux-2.6.32.5/arch/x86/include/asm/unistd_32.h/usr/src/linux-2.6.32.5/include/linux/syscalls.h/usr/src/linux-2.6.32.5/MakefileNew set of files to be createdCreate a new directory newcall/ inside the path “/usr/src/linux-2.6.32.5/” Create new files Makefile, newcall.c and put them in the /usr/src/linux-2.6.32.5/newcall/ folder Create new user files (in any folder of Linux) to test the system call
testnewcall.c, testnewcall.h (created in /home/pradeepkumar) syscall_table_32.S Find the file /usr/src/linux-2.6.32.5/arch/x86/kernel/syscall_table_32.S and add the following line at the end
"…

### Installing TexLive 2019 in Ubuntu 18.04

Installation of TexLive 2019 in Linux (Ubuntu 18.04 LTS)
TeX (Tech)

Installation of TexLive 2019

Please watch the video for full installation

I used .iso file to download, the Total size is 3.3GB for Linux,

Extract the .iso file to a folder and open a terminal

\$] sudo ./install-tl
(it goes into a terminal mode, which is faster compared to the GUI Mode)

\$] sudo ./install-tl -gui
after the installation, set the PATH, MANPATH and INFOPATH as suggested by LATEX

export PATH=\$PATH:/usr/local/texlive/2019/bin/x86_64-linux
export MANPATH=/usr/local/texlive/2019/texmf-dist/doc/man
export INFOPATH=/usr/local/texlive/2019/texmf-dist/doc/info

put these lines in to the /home/pradeepkumar/.bashrc

We have installed TexLive 2019 and texstudio.

To install texstudio

\$] sudo apt install texstudio
The look and feel of TexStudio looks like this image.

texlive, it install everyt…

### Electrical Machine Design (equations)

FactorsDC Machine Transformers Induction Machines Synchronous MachinesOutput EquationPa=CoD2Ln, where Pa=P/h for generators, Pa=P for motorsFor Single Phase
Q=2.22 f Bm Ai Kw Aw d10-3
For Three Phase
Q=3.33 f Bm Ai Kw Aw d 10-3Q=CoD2 L ns
KVA Input Q=
HP * 0.746 / Cos f * hQ=CoD2 L ns
KVA Input Q=
HP * 0.746 / Cos f * h
For Turbo alternators
Q=1.11Bavac KwsVa2 L 10-3/nsOutput CoefficientCo=Bav ac* 10-3where Bav-magnetic loading and ac - electric loadingDNACo=11 Kws Bav ac 10-3Co=11 Kws Bav ac 10-3 Choice of Magnetic LoadingFlux Density in Teeth Frequency of Flux Reversals Size of machineDNAMagnetizing current, Flux Density, Iron lossIron loss, Stability, Voltage Rating, Parallel Operation, Transient ShortCircuit current Choice of Electric LoadingTemperature rise,
speed of machine, Voltage, Armature reaction, CommutationDNAOverload Capacity, Copper losses, Temperature rise, Leakage ReactanceCopper loss, Synchronous reactance, Temperature rise, Stray Load losses,
Voltage rating Flux …