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Member ID: 21

Saugato Ray

Email
Saugatoray@yahoo.co.in

Profile: I am studying for my Bachelorís degree in Computer Information Systems as a sophomore at AIT affiliated to Tarleton State University, Texas. My main interests in Computer Science are in the areas of design of databases. My skills include Windows Programming using C++ and MFC, designing MySQL and Oracle databases with web based PHP and ASP programming.

My hobbies are listening to music, playing musical instruments (Keyboard, Drums(Indian Classical, Western and African), love to make sounds through mouth). I sequence MIDI files. I do pencil sketching and drawing. Love watching TV for Science fiction stories, specially Star Trek series and movies .

Prof. Ashay Dharwadker's Courses (2):

CourseSemesterGrade
Information SystemsFall 2003View
Database SystemsFall 2003View



Projects (1)


Project ID: 6
Course: Database Systems
Topic: Database on Airline Reservation, Ticketing & Scheduling
Description: I am developing my project in partnership with Edward D'Costa.
The database will contain data of flight schedules, ticketing, and reservation, which will include:-
1) dates, days, and time of arrival and departure of airlines;
2) boarding, transit, and destination of different airlines;
3) aircraft numbers;
4) fares of flights;
5) PNR no., name, address and telephone number of passengers.

MySQL queries for our database are as follows:

create table airlines (arl_code varchar(5) not null, arl_comp varchar(25), country varchar(30), addr varchar(100), tel_no varchar(25), primary key(arl_code));

create table aircraft_type (arft_code varchar(10) not null, manuf varchar(15), model varchar(10), capacity int(4), primary key(arft_code));

create table airports (arpt_code varchar(6) not null, arpt_name varchar(50), city varchar(50), country varchar(30), addr varchar(100), tel_no varchar(25), terminals int(3), primary key(arpt_code));

create table passenger (p_sno int(9) not null, lname varchar(30), fname varchar(30), sex varchar(2), age int(3), addr varchar(100), email_id varchar(40), pssprt_no varchar(20), class varchar(10), zone varchar(15), meal varchar(10), assistance varchar(3), primary key(p_sno));

create table passenger_contact (passcon_sno varchar(9) not null, lname varchar(30), fname varchar(30), addr varchar(100), tel_no varchar(25), email_id varchar(40), primary key(passcon_sno));

create table flight_timetable (fl_no varchar(8) not null, days varchar(30), dep_arpt_code varchar(6), dep_datetime datetime, trans_arpt_code varchar(6), trans_datetime datetime, trans_fare decimal(6,2), dest_arpt_code varchar(6), dest_datetime datetime, dest_fare decimal(6,2), primary key(fl_no));

create table universal_time_zone_diff (city varchar(50) not null, country varchar(30), gmt_diff dec(3,2), primary key(city));

create table arln_craft (arl_code varchar(5) not null, arft_code varchar(10) not null, primary key(arl_code, arft_code), foreign key(arl_code) references airlines, foreign key(arft_code) references aircraft_type);

create table pass_con (p_sno int(9) not null, c_sno int(9) not null, primary key(p_sno, c_sno), foreign key(p_sno) references passenger, foreign key(c_sno) references passenger_contact);

create table pass_flight (p_sno int(9) not null, fl_no varchar(8) not null, primary key(p_sno, fl_no), foreign key(p_sno) references passenger, foreign key(fl_no) references flight_timetable);


Seminars (2)


Seminar ID: 12
Course: Information Systems
Topic: Tim Berners Lee's Invention
Description: Tim Berners Lee is the inventer of WWW (World Wide Web) i.e the internet and also HTML (Hyper Text Markup Language). He is one of the inventers who did not take credit for his work. he is has invented a technology which is being logged everyday by billions of people around the world.

Reference: http://infomesh.net/2001/enquire/manual/

Seminar ID: 40
Course: Database Systems
Topic: Firewalls (To be given)
Description: A Firewall is the combination of the two words Fire and Wall, as it is a wall that generates heat or fire to protect the system from the outside world.
  1. Need of Firewalls
  2. What are Firewalls ?
  3. Firewalls Design Principle
  4. Characteristics of a Firewall
  5. General techniques used to control access
  6. Limitations
  7. Types of Firewalls


Research Notes (3)


Research Note ID: 7
Course: Information Systems
Topic: Tower of Hanoi Puzzel
Description: The Tower of Hanoi is sometimes referred to as the "Tower of Brahma" or the "End of the World Puzzle " . This puzzle was invented by the French mathematician Edouard Lucas in 1883 after he got inspired by a legend that tells of a Hindu temple where the pyramid puzzle might have been used for the mental discipline of young priests. Legend says that at the beginning of time the priests in the temple were given a stack of 64 gold disks, each one a little smaller than the one beneath it. Their assignment was to transfer the 64 disks from one of the three poles to another, with one important proviso large disk could never be placed on top of a smaller one. The priests worked very efficiently, day and night. When they finished their work, the myth said, the temple would crumble into dust and the world would vanish.
So he came with a solution to solve this problem and invented this puzzle by applying mathematical logics.
In mathematics he applied Recursive Functions, Stacks and Fecurrence relations. In "Recursion" the formula derived in general for n discs is 2^n-1 .
How to apply Recursive Pattern ?
Simple! follow these steps.
Bascially There are three pegs and the discs have to be moved from the first A i.e (Source) to the last one C i.e (Destination) keeping in mind the two rules that are:
1. not to keep the larger disc on the smaller one and
2.move a disc at a time.
Now in Recursive Pattern:-
1)First, transfer n-1 disks from post A to post B. The number of moves will be the same as those needed to transfer n-1 disks from post A to post C. Call this number M moves.
2)Next, transfer disk 1 to post C [1 move] .
3)Finally, transfer the remaining n-1 disks from post B to post C. [Again, the number of moves will be the same as those needed to transfer n-1 disks from post A to post C, or M moves.]
Therefore the number of moves needed to transfer n disks from post A to post C is 2M+1, where M is the number of moves needed to transfer n-1 disks from post A to post C.
But, if we want to know how many moves it will take to transfer 100 disks from post A to post B, we will first have to find the moves it takes to transfer 99 disks, 98 disks, and so on. Therefore the recursive pattern will not be much help in finding the time it would take to transfer all the disks.
No problem ! the recursive pattern can help us generate more numbers to find an explicit (non-recursive) pattern. Here's how to find the number of moves needed to transfer larger numbers of disks from post A to post C, remembering that M = the number of moves needed to transfer n-1 disks from post A to post C:
for 1 disk it takes 1 move to transfer 1 disk from post A to post C;
for 2 disks, it will take 3 moves: 2M + 1 = 2(1) + 1 = 3
for 3 disks, it will take 7 moves: 2M + 1 = 2(3) + 1 = 7 and so on...

So the formula for finding the number of steps it takes to transfer n disks from post A to post B is: 2^n - 1 where "n" is the number of discs.
for 1 disk 2^1 - 1 = 2 - 1 = 1
for 2 disks 2^2 - 1 = 4 - 1 = 3
for 3 disks 2^3 - 1 = 8 - 1 = 7 and so on...

From this formula you can see that even if it only takes the monks one second to make each move, it will be 2^64 - 1 seconds before the world will end. This is 590,000,000,000 years (that's 590 billion years) - far, far longer than some scientists estimate the solar system will last. That's a really long time!


Refered from:
http://www.cut-the-knot.org/recurrence/hanoi.shtml
http://www.lhs.berkeley.edu/Java/Tower/towerhistory.html .
Little help from my hostel and classmates Superna and Atika .

Research Note ID: 13
Course: Database Systems
Topic: Firewalls
Description: A Firewall is the combination of the two words Fire and Wall, as it is a wall that generates heat or fire to protect the system from the outside world.

Need of Firewalls:-
Your Home computer is safe and secure (No other can access your data). The moment your home computer is connected to Internet the data could be accessed by external users (Hackers) who can steal your data, passwords and credit card number .

What are Firewalls ?
Firewalls are effective means of protecting a local system or network of systems from network-based security threats while at the same time affording access to the outside world via wide area networks and the Internet.
FIREWALLS DESIGN PRINCIPLES :
Information systems in corporations ,government agencies, and other organizations have undergone a steady evolution:
  • Centralized data processing system, with a central mainframe supporting a number of directly connected terminals.
  • Local Area Networks (LANs) interconnecting PCs and terminals to each other and the mainframe.
  • Premises network, consisting of a number of LANs, interconnecting PCs, Servers, and perhaps a mainframe or two.
  • Enterprise-wide network, consisting of multiple, geographically disturbed premises networks interconnected by a private Wide Area Network (WAN).
  • Internet connectivity, in which the various premises networks all hook into the Internet and may or may not also be connected by a private WAN.

What are the Characteristics of a Firewall ?
The following lists are the design goals for a Firewall :
  • All traffic from inside to outside, vice versa, must pass through the firewall.
  • Only authorized traffic, as defined by local security policy, will be allowed to pass .
  • The firewall itself is immune to penetration. This implies the use of a trusted system with a secure operating system.


FOUR GENERAL TECHNIQUES USED TO CONTROL ACCESS :
  • Service control: Determines the types of Internet services that can be accessed, inbound or outbound. The firewall may filter traffic on the basis of IP (Internet Protocol) address and TCP (Transport Control Protocol) port number; may provide proxy software that receives and interprets each service request before passing it on.
  • Direction control: Determines the direction in which particular service requests may be initiated and allowed to flow through the firewall.
  • User control: Controls access to a service according to which user is attempting to access it. This feature is typically applied to userís inside the firewall perimeter (local users). It may also be applied to incoming traffic from external users.
  • Behavior control: Controls how particular services are used. For example, the firewall may filter e-mail to eliminate spam, or it may enable external access to only a portion of the information on a local Web server.

CAPABILITIES OF FIREWALL :
  • It provides protection from various kinds of IP spoofing and routing attacks.
  • It provides a location for monitoring security-related events.
  • It is a convenient platform for several Internet functions that are not security related.
  • It can be used to implement virtual private networks.

FIREWALLS HAVE A NUMBER OF LIMITATIONS:
  • Firewalls must be updated with a list of inappropriate banned websites, as new sites appear very quickly.
  • Firewalls are not an effective protection against software viruses. We recommend that all users install anti--virus software.
  • Often Firewalls are positioned between an Internet router and the internal LAN, this results in a network bottleneck. Careful consideration should be paid to where a firewall is placed. We recommend that the firewall is installed between a switch and an Internet router.
  • Firewalls cannot protect against 'back doors', where a single network user has installed a separate Internet connection. To prevent this, companies should put an effective Internet access policy in place.
  • Equipped with the correct password, hackers can gain access to your network in spite of a firewall. To solve this, all passwords should be changed regularly.
  • The firewall does not protect against internal threats, such as disgruntled employee or an employee who unwittingly cooperates with an external attacker.

TYPES OF FIREWALLS
There are three types of firewalls:
  • Packet-Filtering Router
  • Application-Level Gateway
  • Circuit-Level Gateway


Research Note ID: 39
Course: Database Systems
Topic: Relational Algebra in MySQL
Description: The 8 operators for Coddís relational algebra are :
  • Restriction
  • Projection
  • Product
  • Union
  • Intersection
  • Difference
  • Join
  • Division

Defination and examples of the 8 operators :


TABLE1 :SUPPLIERS
S SName Status City
S1 Smith 20 London
S2 Jones 10 Paris
S3 Blake 30 Paris
S4 Clark 20 London
S5 Adams 30 Athens
TABLE2 :PARTS
P PName Color Weight City
P1 Nut Red 12 London
P2 Bolt Green 17 Paris
P3 Screw Blue 17 Rome
P4 Screw Red 14 London
P5 Cam Blue 12 Paris
P6 Cog Red 19 London
TABLE3 :SHIPMENTS
S P Quantity
S4 P2 200
S3 P2 200
S2 P2 400
S2 P1 300
S1 P6 100
S1 P4 200
S1 P3 400
S4 P5 400
S4 P4 300
S1 P2 200
S1 P1 300
  1. Restriction : Returns a table containing all records from a specified table that satisfy a specific condition.
    Query : select * from shipments where Quantity<150;

  2. Projection : Returns a table containing all (sub) records that remain in a specified fields have been removed.
    Query : select S, City from suppliers;

  3. Product : Returns a table containing all possible records that are a combination of two records, one from each of two specified tables.
    Query : select * from suppliers, parts where suppliers.S = "S1" and parts.P = "P1";

  4. Union : Returns a table containing all records that appear in either or both of two specified tables.
    Query : select * from suppliers, parts where suppliers.S = parts.P union select *from suppliers, parts where suppliers.S<>parts.P;

  5. Intersection : Returns a table containing all records that appear in both of two specified tables.
    Query : select * from suppliers, parts where suppliers.S = parts.P;

  6. Difference : Returns a table containing all records that appear in both of two specified tables.
    Query : still searching .

  7. Join : Returns a table containing all possible records that are a combination of two records one from each of two specified tables, such that the two records contributing to any given combination have a common value for the common fields of the two tables (and that common value appears just once, not twice in the resulting record).
    Query : select suppliers.S, SName, Status, City, P, Quantity from suppliers, shipments where suppliers.S = shipments.S;

  8. Division : Takes two single-field tables and one double-field table and returns a table containing all records from one single-field table that appear in the double-field table matched with all records in the other single-field table.
    Query : still searching .

Last updated on Monday, 24th November 2003, 07:34:45 AM.

Prof. Ashay Dharwadker