Polaris Recruiting Freshers and Experienced in all Technology

2008 and 2009 is the worst period for the Software industry. Software industry was developed now and many companies have started recruiting people including freshers. I am working in Polaris Software lab ltd. 

Polaris is recruiting Freshers and Experienced in all the technologies. You can apply for the jobs in online. More than 1000 vacancies are available in Polaris. Most of the vacancies are in Chennai.

You have to register in the website to apply for the job. You will receive your Login ID and Password to your mail. You need to upload the resume in Online. HR people will review your resume and they will call you, if they are interested in your profile. 

Click here to know more details.

How to encrypt the password (or) How to encrypt a string

Cryptography plays an important role in the computing world.  All the passwords will be saved in the encrypted format. All the organizations and the websites will store their user’s password in encrypted format. No one will save the password in plain format. Many problems will arise if the passwords were saved in plain format. For example, if the passwords were saved in plain format in the file or in the oracle database, hackers can easily _­­access the file and access their accounts and can transfer all the money to their accounts.

Because of the above said problems, scientists have started the concept of cryptography. The main concept of cryptography is to change the password into some other text and save the changed password in some files or in table. When the user enters the password the password will be encrypted and the password will be compared with the password stored in the password file (if UNIX machine) or in password table.

Many encryption and decryption algorithms are there in the computing technology. Many people had spent their whole life for cryptography. The first encryption program was written for Unix Operating System to maintain the user’s password.

crypt is the common c function used to crypt the string. It is the library function. This function is the one-way encryption method. There is no decryption program or the function is available. The crypt function will have two arguments. First argument is the password and the second argument is the salt. This function will take only the first eight digits and take the first two digits of the salt and create the encrypted password.

The encrypted password is of eight digits. The first two digit of the encrypted password contains the salt key used. The resulting 6 digits is the encrypted password. Crypt function uses the AES like algorithm.

Syntax for crypt function:

crypt( char *key, char *salt);

Sample program to encrypt the string:

#include<stdio.h>

#include<unistd.h>

main()

{

          char    passwd[10];

          char    salt[3];

          char    *encpasswd;

         

          printf("Enter the passwd:");

          scanf("%s",passwd);

          printf("Enter the Salt Key:");

          scanf("%s",salt);

         

          encpasswd =  crypt(passwd, salt);

         

          printf("The crypted passwd is: [%s]\n",encpasswd);

          exit(0);

}

The above program will encrypt the passwd and return the encrypted password to the encpasswd. This program works fine in the unix environment. 

Trick to list the links in the Google search page

As students we will use the internet for our assignments and for our projects. Some students will even use the internet for their knowledge. I hope 99% of the people will use the Google search engine. Have you ever wondered how the search engine is listing the website links and most of the times some websites link will always in the top. The link of some websites will always be in the first page. To bring the link in the first page is very simple. 

There are many ways to bring the link to the first page. First the topic should be simple. The topic should be chosen in such a way that relevant to the topic and should contain the hot keyword of the users search. For a particular topic people will search the content with similar keywords. If the keyword matches to the topic, the link will be displayed in the Google pages. If many people clicked the link, the link will display in the first page of Google search engine. 


The second way to list the links in the first page is to submit link in the social network sites and the links exchange sites. When the link was submitted in these sites many people will visit the website through the links. This will bring the traffic to the websites and the site will get the page rank according to the popularity of the link and by the quality of the contents. 

Wipro is recruting BE/B.Tech 2010 passedouts

Its already one year over for the 2010 batches. Usually Software companies won't recruit freshers when they have more than one year gap. But with the recession of the last few years IT companies are recruiting freshers even they have more than one year gap. Wipro has called the 2010 passed out batches to attend the interview. They are recruiting 2010 BE/B.Tech passed outs. Even they are calling for the 2009 passed outs. I hope this is the last chance for the 2009 and 2010 passed outs. You can apply directly from the Wipro's website. Click Here to apply to Wipro. This link will redirect you to the Wipro's website. Last day to apply for this job is 30th May 2011. Apply for the job. They will call you or mail you for the interview. All the best for your interview.

Chetanas has created a new website for Java Programers

Day by day JAVA programmers are increasing. Most of the applications are done through Java coding. We can do any kind of applications with JAVA. All the companies are hiring JAVA professionals. Every company are in need of JAVA professionals. Its easy to get a job if you know JAVA. But the pay will be vary from company to company. Chetanas forun is one of the best online job portal as they are doing  wonderful job for the freshers as well as the experienced professionals. The percentage of fake jobs was less when compared to other job portals. We can assure the company posted in chetanas forum was a good company. Now Chetanas forum has a new portal for JAVA professionals. We can search JAVA programming vacancies in this portal.Click Here to visit the portal for JAVA vacancies. The portal name is http://javaken.com

DIGITAL IMAGING PROCESSING ONE MARK

DIGITAL IMAGE PROCESSING

1. Preprocessing of an image is done in

image acquisition
image segmentation
image restoration
image enhancement

2. Which process is called subjective process?

image acquisition
image segmentation
image restoration
image enhancement

3. Which process is called an objective process?

image compression
image segmentation
image restoration
image enhancement

4. Which process split an input image into its constituent parts

image acquisition
image segmentation
image restoration
image enhancement

Which process involves the mathematical or probabilistic methods in its operation

image acquisition
image segmentation
image restoration
image enhancement

6. Which process is used in improving image contrast?

image acquisition
image segmentation
image restoration
image enhancement

7. Which Process is used in removal of optical distortions?

image acquisition
image segmentation
image restoration
image enhancement

8. Which technique is used for reducing the storage required to save an image

image compression
image segmentation
image restoration
image enhancement

9. Which Process is used in sharpening or de-blurring an out of focus image?

image acquisition
image segmentation
image restoration
image enhancement

10. Which Process is used in removing periodic interference?

image acquisition
image segmentation
image restoration
image enhancement

11. Which process uses tools for extracting image components

Compression
Morphological Processing
Restoration.
Segmentation

12. Which Process involves removing of blur caused by linear motion?

image compression
image segmentation
image restoration
image enhancement

13. Which process transforms raw data into a form suitable for subsequent processing

Image Representation
Morphological Processing
Image Restoration
Image compression

14. Which process is also called feature selection?

Image Description
Morphological Processing
Image Restoration
Image Segmentation

15. Which is the process that assigns a label (e.g., “vehicle”) to an object based on its descriptors?

Image Description
Morphological Processing
Image Recognition
Image Segmentation

16. In each eye, cones are in the range of

6-7 million.
75-150 million
65-75 million
5-7 million

17. In each eye, rods are in the range of

6-7 million
75-150 million
65-75 million
5-7 million

18. Scotopic vision is also called as

Dim light vision
Bright light vision
Moderate vision
No vision

19. Photopic vision is also called as

Dim light vision
Bright light vision
Moderate vision
No vision

20. Cone vision is called as

Dim light vision
Bright light vision
Moderate vision
No vision

21. The observer is looking at a tree15 m high at a distance of 100 m , Calculate the height in mm of
that object in the retinal image

0.15 mm
2.55 mm
0.55 mm
6.66 mm

22. Weber Ratio is given by

∆i * i
∆i / i
i /∆i
i-∆i

23. The spatial interaction of Luminance from an object and its surround creates a phenomenon
called

Subjective brightness
Brightness adaptation
Mach band effect
Simultaneous Contrast

24. Intensity as preserved by the human visual system is called as

Subjective brightness
Brightness adaptation
Mach band effect
Simultaneous Contrast

25. Which operation increases the dynamic range of the gray levels in the image?

Subjective brightness
Brightness adaptation
Mach band effect
Contrast stretching

26. Digitizing the amplitude values is called

Quantization
Compression
Sampling
Restoration

27. Digitization of spatial coordinates (x,y) is called

Quantization
Compression
Sampling
Restoration

28. Which type of image is commonly used as a multiplier to mask regions within another image.

Binary images
Indexed Images
Gray scale image
RGB image

29. Find the number of bits required to store a M X N image with 2m gray levels?

M X N X m bits
m X N bits
M X N bits
m X M bits

30. Find the number of bits required to store a 256 X 256 image with 64 gray levels?

655360 bits
65536 bits
393216 bits
327680bits

31. Find the number of bits required to store a 512 X 512 RGB color image with 2 grey levels?

.786 MB
.262 MB
512 MB
1024 MB

32. The Euclidean distance between p and q is defined as

Max | ( x – s ) | , | ( y – t ) |
[( x – s )2 + ( y – t ) 2 ]
[( x – s )2 + ( y – t ) 2 ]1/2
|(x–s)|+|(y–t)|

33. Chess board (D8) distance is calculated by

Max | ( x – s ) | , | ( y – t ) |
[( x – s )2 + ( y – t ) 2 ]
[( x – s )2 + ( y – t ) 2 ]1/2
|(x–s)|+|(y–t)|

34. The effect of aliased frequencies can be seen under the right conditions in the form of so called

Moire Patterns
Brightness adaptation
Mach band effect
Simultaneous Contrast

35. City block (D4) distance is calculated by

Max | ( x – s ) | , | ( y – t ) |
[( x – s )2 + ( y – t ) 2 ]
[( x – s )2 + ( y – t ) 2 ]1/2
|(x–s)|+|(y–t)|

36. Give the relation for 1d DCT

1/N x=0∑N-1 f(x) exp [-j2πux/N]

α(u) x=0∑N-1f(x)cos[(2x+1)uπ/2N]

N −1

∑

1/N

x =0

1/N

x=0∑ N-1 f(x) i=0

f(x) (-1) ∑i =0

Π n-1 (-1) bi (x) bn-1-I (u)

37. Give the relation for 1d DFT

1/N x=0∑N-1 f(x) exp [-j2πux/N]

α(u) x=0∑N-1f(x)cos[(2x+1)uπ/2N]

N −1

∑

1/N

x =0

1/N

x=0∑ N-1 f(x) i=0

f(x) (-1) ∑i =0

Π n-1 (-1) bi (x) bn-1-I (u)

38. Give the relation for Hadamard Transform

1/N x=0∑N-1 f(x) exp [-j2πux/N]

α(u) x=0∑N-1f(x)cos[(2x+1)uπ/2N]

N −1

1/N

∑

x =0

1/N

x=0∑ N-1 f(x) i=0

f(x) (-1) ∑i =0

Π n-1 (-1) bi (x) bn-1-I (u)

39. Give the relation for Walsh Transform

1/N x=0∑N-1 f(x) exp [-j2πux/N]

α(u) x=0∑N-1f(x)cos[(2x+1)uπ/2N]

N −1

∑

1/N

x =0

1/N

x=0∑ N-1 f(x) i=0

f(x) (-1) ∑i =0

Π n-1 (-1) bi (x) bn-1-I (u)

40. Which model is used for color monitor & color video camera?

RGB model
CMY model
YIQ model
HIS model

41. Which model is used for color printing?

YIQ model
CMY model
HIS model
RGB model

42. Which model is used for color image processing?

RGB model
YIQ model
CMY model
HIS model

43. Which model is used for color picture transmission?

RGB model
YIQ model
HIS model
CMY model

44. Zooming of digital images may be viewed as

over sampling
under sampling
flat sampling
critical sampling

45. Shrinking of digital images may be viewed as

over sampling
under sampling
flat sampling
critical sampling

46. Give the Conditions for perfect transform

Transpose of matrix ! = Inverse of a matrix.
Transpose of matrix = ( inverse of a matrix )2
Transpose of matrix = Inverse of a matrix
Transpose of matrix = ( inverse of a matrix )1/2.

47. Which transform is called very fast transform?

HAAR Transform
HADAMARD Transform
SINE Transform
COSINE Transform

48. Which transform has very poor energy compaction for images?

COSINE Transform
HADAMARD Transform
SLANT Transform
HAAR Transform

49. Which transform has very good energy compaction for images?

COSINE Transform
HADAMARD Transform
SLANT Transform
HAAR Transform

50. The basic vectors of Slant matrix are

Uniformly ordred
sequensely ordered
Randomly ordred
not sequensely ordered

51. The basic vectors of HAAR matrix are

Uniformly ordred
sequensely ordered
Randomly ordred
not sequensely ordered

52. Which Transform is an optimal in the sense that it minimizes the mean square error between the
vectors X and their approximations X^?

KL Transform
HADAMARD Transform
SLANT Transform
HAAR Transform

53. Which Transform is very good energy compaction for highly correlated images?

KL Transform
HADAMARD Transform
SLANT Transform
HAAR Transform

54. Which Transform has excellent energy compaction for highly correlated data?

SLANT Transform
HADAMARD Transform
COSINE Transform
HAAR Transform

55. A measure of the smallest discernible detail in an image is

Intensity Resolution
Frequency Resolution
Spatial resolution
Spectral resolution

56. The negative of an image with gray levels in the range [0,L-1] is obtained by using the negative
transformation given as:

s=(L+1)-r
s=(L-1)-r
s=(L-1)+r
s=(L+1)+r

57. Which domain refers to image plane itself?

Laplace
Frequency
Spatial
Spectral

58. Which method is based on modifying the image by Fourier transform?

Image domain
Frequency domain
Spatial domain
Spectral domain

59. Which operation reduces an image of higher contrast than the original by darkening the levels
below m and brightening the levels above m in the image?

Contrast stretching
Grey level slicing
Bit plane slicing
Subjective Brightness

60. Which operation is used in enhancing masses of water in satellite imagery?

Contrast stretching
Grey level slicing
Bit plane slicing
Subjective Brightness

61. Which operation is used in enhancing flaws in x-ray images?

Contrast stretching
Grey level slicing
Bit plane slicing
Subjective Brightness

62. Which operation is used in highlighting the contribution made to total image appearance by
specific bits might be desired?

Contrast stretching
Grey level slicing
Bit plane slicing
Subjective Brightness

63. The histogram of a digital image with gray levels in the range [0,L-1] is h(rk)=

k
nk
n
n/k

64. An information about the degradation must be extracted from the observed image either explicitly
or implicitly is called as

Blind image restoration
Inverse Filtering
Least Mean square filtering
Singular value Decomposition

65. This PDF P(Z)= 2(z-a)e-(z—a)2/b/b for Z>=a belongs to which noise model?

Gaussian noise
Erlang noise
Rayleigh noise
Impulse Noise

66. This PDF P(Z)=e-(Z-µ)2/2σ2/√2πσ belongs to which noise model?

Gaussian noise
Gamma Noise
Rayleigh noise
Impulse Noise

67. This PDF P(Z)=ab zb-1 ae-az/(b-1) for Z>=0 belongs to which noise model?

Gaussian noise
Erlang noise
Uniform noise
Gamma Noise

68. This PDF P(Z)= ae-az

Z>=0 belongs to which noise model?

Gaussian noise
Exponential noise
Rayleigh noise
Gamma Noise

69. This PDF P(Z)=1/(b-a) if a<=Z<=b belongs to which noise model?

Gaussian noise
Erlang noise
Uniform noise
Gamma Noise

70. ------------ is the process of recovering the input of the system from its output?

Blind image restoration
Inverse Filtering
Least Mean square filtering
Singular value Decomposition

71. Wiener filtering is a method of restoring images in the

presence of blurr as well as noise
presence of noise only
abscence of blurr as well as noise
absence of blurr only

72. Which transform gives best energy packing efficiency for any given image?

SLANT Transform
HADAMARD Transform
SVD Transform
HAAR Transform

73. Which transform is useful in the design of filters finding least square?

SLANT Transform
HADAMARD Transform
KL Transform
SVD Transform

74. Hotteling Transform is also called as

KL Transform
HAAR Transform
SLANT Transform
SVD Transform

75. Which transform involves Principle of component analysis

SLANT Transform
HADAMARD Transform
KL Transform
SVD Transform

76. The basis of reduction process is removal of redundant data is called

image compression
image segmentation
image restoration
image enhancement

77. The pseudo inverse filter is defined as

H^(u,v)=1/(H(u,v)
H^(u,v)=1/(H(u,v)
H^(u,v)=(H(u,v)
H^(u,v)=(H(u,v)

78. This function represents which filter?

Contra harmonic mean filter
Geometric mean filter
Harmonic filters
Arithmetic mean filter

79. This function represents which filter?

Arithmetic mean filter
Geometric mean filter
Harmonic filters
Contra harmonic mean filter

80. This function represents which filter?

Arithmetic mean filter
Geometric mean filter
Contra harmonic mean filter
Harmonic filters

81. This function represents which filter?

Arithmetic mean filter
Geometric mean filter
Harmonic filters
Contra harmonic mean filter

82. The effect of salt and pepper noise can be eliminated using

Arithmetic mean filter
Geometric mean filter
Contra harmonic mean filter
Harmonic filters

83. Which filter has positive coefficient near the center and negative in the outer periphery.

Median filter
High pass spatial filter
Derivative filter
Low pass spatial filter

84. The first derivative at any point in an image is obtained by using

Laplacian at that point
the magnitude of the gradient at that point
the phase of the gradient at that point
Fourier transform at that point

85. The second derivative at any point in an image is obtained by using

Laplacian at that point
the magnitude of the gradient at that point
the phase of the gradient at that point
Fourier transform at that point

86. Compression Ratio =

original size - compressed size: 1
original size * compressed size: 1
original size + compressed size: 1
original size / compressed size: 1

87. Which is a technique used to reduce the size of a repeating string of characters?

Huffman coding
Runlength coding
Arithmetic coding
LZW coding

88. Run length coding is the example of

coding redundancy
compression redundancy
psycho visual redundancy
interpixel redundancy

89. ------------ transforms the input data into non-visual format.

Symbol encoder
Mapper
Quantizer
Symbol decoder

90. Which of this step is omitted if the system is error free.

Symbol encoder
Mapper
Quantizer
Symbol decoder

91. ----------- reduces the coding redundancy.

Symbol encoder
Mapper
Quantizer
Symbol decoder

92. ---------- reduces the interpixel redundancy.

Symbol encoder
Mapper
Quantizer
Symbol decoder

93. -------------- reduces the psycho visual redundancy of the input images.

Symbol encoder
Mapper
Quantizer
Symbol decoder

94. Hamming code is the example for

Symbol encoder
Mapper
Quantizer
Channel encoder

95. Variable Length Coding reduces

coding redundancy
compression redundancy
psycho visual redundancy
interpixel redundancy

96. A code word that is not a prefix of any other code word is called

Huffman code
Block code
Instantaneous code
Arithmetic code

97. One to one corresponds between source symbols and code word doesn’t exist in

Huffman code
Block code
LZW code
Arithmetic code

98. JPEG stands for

Joint Pixel Expert Group
Joint Photographic Expert Group
Joint Photographic Expand Group
Joint Picture Expert Group

99. Data Redundancy Rd =

1-Cr
1/Cr
1-1/Cr
1+1/Cr

Calculate the data redundancy if N1 = 2 , n2 =1

0.5
1
0
-1


Download this one mark with Answers

PREPARED BY

___
Er. M. ARUN M.E. MIEEE, MISTE

LECTURER ECE

Lock and Unlock Folders Using Text files

Windows needs special software's to lock and unlock the files. But windows itself providing the feature to lock and unlock the files. Here i am going to explain about the options to lock and unlock the files using the notepad.


 First create a folder with any name (ex. bensh)

Now open a notepad and type the following inthe notepad

ren bensh bensh.{21EC2020-3AEA-1069-A2DD-08002B30309D}

now save the file with the name lock.bat.

Now open a new notepad and type the following in the notepad.

ren bensh.{21EC2020-3AEA-1069-A2DD-08002B30309D}bensh

now Save the file with the name key.bat.

Now Double click on the lock.bat file.

The folder will be locked.

To open the folder double click on the key.bat file.

Note that the lock.dat and the key.dat files should be in the same folder where the bensh folder was there.

This lock technique will not work in the Windows 7 OS.

Clean Up your PC and Improve the performance

Most of the people are using computers. All the offices and colleges have the computers for the business as well as for educational purpose. The computer’s plays an important role in the technology world. Every people are in need of computers in their daily life. Many applications have come to improve the business. 

Every one use computer. But not everyone use the computer efficiently. Most of the computers will slow down the performance after some months. This is because of the unwanted memory in the hard disk.  Windows provides some tools to improve the performance of the computer. These tools are Disk Cleanup, Disk Defragmenter, and Check Disk. We will see about how to do Disk Cleanup and make your computer works faster. Better do automatic schedule for Disk cleanup instead of doing it manually. 

Follow the below steps to perform the Disk Cleanup:

Windows 7:

1. Open Task Scheduler: Click the Start button, click Control Panel, click Administrative Tools, and then double-click Task Scheduler. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
2. Click the Action menu, and then click Create Basic Task. This opens the Create Basic Task Wizard.
3. Type a name for the task and an optional description, and then click Next.
4. To select a schedule based on the calendar, click Daily, Weekly, Monthly, or One time, and then click Next.
5. Specify the schedule you want to use, and then click Next.
6. Click Start a program, and then click Next.
7. Click Browse, and, in the File name box, type cleanmgr.exe, click Open, and then click Next.
8. Click Finish.

Windows Vista

1. Open Task Scheduler: Click the Start button, click Administrative Tools, and then click Task Scheduler. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
2. Click the Action menu, and then click Create Basic Task.
3. Type a name for the task and an optional description, and then click Next.
4. To select a schedule based on the calendar, click Daily, Weekly, Monthly, or One time, and then click Next.
5. Specify the schedule you want to use, and then click Next.
6. Click Start a program, and then click Next.
7. Click Browse, and, in the File name box, type cleanmgr.exe, click Open, and then click Next.
8. Click Finish.

Windows XP

1. Click Start, and then click Control Panel.
2. Click Performance and Maintenance.
3. Under or pick a Control Panel icon, click Scheduled Tasks.
4. In the Scheduled Tasks window, double-click Add Scheduled Task.
5. In the Scheduled Task Wizard, click Next.
6. Scroll down to Disk Cleanup in the list of Applications, click it (to highlight it), and then click Next.
7. Under Perform this task, click Weekly, and then click Next.
8. Set the time and day of the week you would like to run Disk Cleanup. For best results, choose a time when you're typically at your computer so you can provide any required input. Click Next.
9. Type your password in both the Enter the password and Confirm password boxes, and then click Next.
10. Click Finish.

Best fun kid School items for your kids

Kids are the life for their parents. Every one love their kids. People will do more for their kids. They take care of their kids very much. They spend most of their time for their kids. school days are most memorable for the kids. Parents will do what ever they want in their school days. In the school days they will take the lunch in the lunch bags. kids lunch totes will be perfect for the cute kids. Many types of totes are available. They are available in variant colors and various designs. The best days in the school days are the picnic and the tours arranged in the college. Kids will take the bags to carry their clothes and their snacks to the vacation tours. Get the small duffle bags to the kids. Small kids will like the duffle bags very much. Because they comes in different colors and designs. They comes with very quality material. The duffle bags comes with the very cheap cost. The small duffle bags comes with the starting range of $17.99. Variety of designs were embedded in the duffle bag. People can choose from the best designs they like. Every people likes the back bag. People likes the back bag when it comes with good quality cloth and with good design. If you are looking for the best back bag, then Stephen Joseph toddler backpacks is the best choice for you. You can get the back bags from $7.00 itself. You can also buy the bags in online. You will get the best design with the good material at this cost from Stephen Joseph toddler backpacks  only. Get the best bags for your kids and make them happy and save your money. The back bags will last for more than three or four years. Save your money and get more than for the money you spend.

Shell Types in Unix

Just like people know different languages and dialects, your UNIX system will usually offer a variety of shell types:
sh or Bourne Shell: the original shell still used on UNIX systems and in UNIX-related environments. This is the basic shell, a small program with few features. While this is not the standard shell, it is still available on every Linux system for compatibility with UNIX programs.

bash or Bourne Again shell: the standard GNU shell, intuitive and flexible. Probably most advisable for beginning users while being at the same time a powerful tool for the advanced and professional user. On Linux, bash is the standard shell for common users. This shell is a so-called superset of the Bourne shell, a set of add-ons and plug-ins. This means that the Bourne Again shell is compatible with the Bourne shell: commands that work in sh, also work in bash. However, the reverse is not always the case. All examples and exercises in this book use bash.

csh or C shell: the syntax of this shell resembles that of the C programming language. Sometimes asked for by programmers.

tcsh or TENEX C shell: a superset of the common C shell, enhancing user-friendliness and speed. That is why some also call it the Turbo C shell.

ksh or the Korn shell: sometimes appreciated by people with a UNIX background. A superset of the Bourne shell; with standard configuration a nightmare for beginning users.
·
The file /etc/shells gives an overview of known shells on a Linux/Unix system:

mia:~> cat /etc/shells
/bin/bash
/bin/sh
/bin/tcsh
/bin/csh

Your default shell is set in the /etc/passwd file, like this line for user pertsch:

pertsch:L2NOfqdlPrHwE:504:504:pertsch Maya:/home/pertsch:/bin/bash

To switch from one shell to another, just enter the name of the new shell in the active terminal. The system finds the directory where the name occurs using the PATH settings, and since a shell is an executable file (program), the current shell activates it and it gets executed. A new prompt is usually shown, because each shell has its typical appearance:

pertsch:~> tcsh

ORBI-SCH=>