Advantages of Simulation

Introduction

A simulation is the manipulation of the model in such a way that it operates on time or space to compress it thus enabling one to perceive the interaction that would not otherwise be apparent because of their operation in time or space. It is a concept for developing a level of understanding of the interaction of the parts of the system and of the system as a whole.

Simulation is a powerful technique for solving wide variety of problems. Simulation in general is to pretend that one deals with a real thing while really working with an imitation. Simulation can be done by hand or on a computer. The term simulation is generally used to describe any procedure of establishing a model and deriving a solution numerically.

Some definition of simulation:

1.       Simulation is a representation of reality through the use of a model which will react in the same manner as reality under the given set of conditions.

2.       Simulation is a numerical technique for conducting experiment on a digital computer which involves certain types of mathematical and logical relationship necessary to describe the behavior and the structure of a complex real world system over extended period of time.

3.       Simulation may be defined as one which depicts the working of large scale system of men, machines, materials and information operating over a period of time in a simulated environment of the actual real world conditions.

Following are the advantages of simulation 

1.       New policies, operating procedures, decision rules, information flows, and organizational procedures and so on can be explored without disrupting ongoing operations on the real system.

2.       New hardware designs, physical layouts, transportation system and so on, can be tested without committing resources to their acquisition.

3.       Hypothesis about how or why certain phenomena occur can be tested for feasibility.

4.       Time can be compressed or expanded allowing for a speedup or slowdown of the phenomena under investigation.

5.       Insight can be obtained about the importance of variables to the performance of the system.

6.       Bottleneck analysis can be performed.

7.       Insight can be obtained about the interaction of variables.

8.       A simulation study can help in understanding how the system operates rather than how individual thing the system operates.

9.       “what-if” questions can be answered. This is particularly useful in designs of new systems.

Limitation of the simulation technique.

1.       Model building requires special training. It is an art that is learned over time and through experience. Furthermore, if two models are constructed by two competent individuals, they may have similarities, but it is highly unlikely that they will be the same.

2.       Simulation results may be difficult to interpret. Since most simulation outputs are essentially random variables (they are usually based on random inputs, it may be hard to determine whether an observation is a result of system interrelationships or randomness.

3.       Simulation modeling and analysis can be time consuming and expensive

4.       Simulation is used in some cases when an analytical solution is possible.

The processor

The processor

A microprocessor is a multipurpose, programmable, clock driven, register based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions and provides result as output. The processor (really a short form for microprocessor and also often called the CPU (Central Processing Unit) is the central component of the PC. In another sense, microprocessor is IC chip which contains ALU, memory unit which performs all related operations and control all parts. This vital component is in some way responsible for every single thing the PC does.

When the Hungrian born John Von Newmann, first suggested storing a sequence of instruction (a program) in the same memory as the data, it was a truly innovative idea. That was in his "First Draft of a Report on the EDVAC", written in 1945. The report organized the computer system into four main parts: the Central Arithmetical unit, the Central Control Unit, the Memory and the Input/ Output devices. Today, more than half a century later, nearly all processors have a Von Newmann's architecture.

Principle:

The underlying principle of all computer processors are the same. Fundamentally, they all take signals in the form of 0's and 1's(thus binary signals), manipulate them according to a set of instructions, and produce output in the form of 0's and 1's. the voltage on the line at the time a signal is sent determines whether the signal is a 0 or a 1. On a 3.3 volt system, an application of 3.3 volts means that it's a 1, while an application of 0 volts means it's a 0.

Processors work by reacting to an input of 0's and 1's in specific ways and then returning an output based on the decision. The decision itself happens in a circuit called a logic gate, each of which requires at least one transistor, with the inputs and outputs arranged differently by different operations. The fact that today's processors contain millions of transistors offers a clue as to how complex the logic system is. The processor's logic gates work together to make decisions using Boolean logic, which is based on the algebraic system established by mathematician George Boolean. The main Boolean operators are AND, OR, NOT and NAND (AND with NOT), many combinations of these are possible as well.

The flow of electricity through each gate is controlled by that gate's transistor. However, these transistors aren't individual and discrete units. Instead, large numbers of them are manufactured from a single piece of silicon (or other semiconductor material) and linked together without wires or other external materials. These units are called Integrated Circuits (ICs), and their development basically made the complexity of the microprocessor possible. The integration of circuits didn't stop with the first ICs. Just as the first ICs connected multiple transistors, multiple ICs became similarly linked, in a process known as Large-Scale Integration (LSI); eventually such sets of ICs were connected in a process called Very Large Scale Integration(VLSI).

Modern day microprocessor contain tens of millions of microscopic transistor. Used in combination with resistors, capacitors and diodes, these make up logic gates. Logic gates make up integrated circuits, and ICs make up electronic system. Intel's first claim to fame lay in its high level integration of all the processor's logic gates into a single complex processor chip. The Intel 4004 released in late 1971. This was 4-bit microprocessor, intended for use in calculator. It processed data in a 4 bits, but its instructions were 8 bits long.

According to von-Newmann, the overall computer system has input device to input data and information, central processing unit to process input data, and output devices to output the result after processing which in shown in above figure. Computer does not understand user's information directly, so we need input devices to give information to the computer to converts users information in computer understandable form. Keyboard, mouse, joystick, digital camera are the examples of input devices. Every input device has their own function e.g. the use of keyboard is to input text and character input, function of mouse is to select the options, highlight the portion of documents etc. like this, function of digital camera is to input images and photos etc.

After input the data by the user that data will go to central processing unit which is most important part, of computer. It have different parts like control unit to control all parts of computer system. ALU to perform arithmetic and logical operations, memory unit to store data etc. Arithmetic operations means calculations like addition, subtraction, multiplication, division, square root etc. in this way, logical operation means AND, OR, NOT operation. Logical operations are mainly used for decision. To perform any operation ALU receives data from memory, that memory is called register. So, after input data, data will store in memory and system performs operation for that data and gives result. The result is either stored in secondary memory or give result from output devices. All the system and operations are control by clock pulses which is generated by control unit. If the user need result or any data in future use then that data can be save in secondary memory. So, secondary memory is that type of memory which can store data without electricity. This type of memory is called non-volatile memory.

The result or output of central processing unit can not directly understand by user therefore that result should be converting to user understandable form. That function is performed by output devices like printer which gives output in the form of hard copy, monitor which gives the output in displayed form, speaker which gives output in the form of sound etc.

Power Supply

Power Supply

The internal power supply is responsible for converting your standard household power into a form that your computer can use. The power supply is responsible for powering every device in your computer; if it has a problem or is of low quality you may experience many difficulties that you may not realize are actually the fault of the electrical system. This section discusses what makes up the power supply and how it works in detail. In depth, power supply of computer has following function.

1. it converts household AC power supply to DC power because the computer system use (-12 V to +12 V) DC power in computer system but household power supply of NEA in 220V.

2. it distributes power supply in different parts of computers system through different cable according to requirement of parts

The power supply plays an important role in the following areas of your system:

Stability: A high quality power supply with sufficient capacity to meet the demands of your computer will provide years of stable power for your PC. A poor quality or overloaded power supply will cause all sorts of glitches that are particularly insidious, because the problems occur in other, seemingly unrelated, parts of the system. For example, power supplies can cause system crashes, can make hard disks develop bad sectors, or cause software bugs to appear, problems which can be very difficult to trace back to the power supply.

Cooling: The power supply contains the main fan that controls the flow of air through the PC case. This fan is obviously a major component in your PC's cooling system.

Energy Efficiency: Newer PC power supplies work with your computer's components and software to reduce the amount of power they consume when idle. This can lead to significant saving over older systems.

Expandability: The capacity of your power supply is one factor that will determine your ability to add new drives to your system, or upgrade to a more powerful motherboard or processor. Many people don't realize, for example, that a high-speed Athlon CUP and motherboard consume far more power than a similar Pentium-based system, and the power supply needs to be able to provide this power. If you build a new system with a power supply that barely meets your needs, you may have to replace it when you upgrade down the road.

Power Supply Types

Power supplies typically have two basic design formats, known as linear and switched-mode. The linear supply is a relatively simple design that becomes increasingly bulky and heavy for high amperage devices, the switched supply is capable of being much smaller and more efficient but its design is much more complex and sophisticated.

Linear Power Supply

It does not have any feedback of power, therefore it is called linear power supply and the design is also simple.

A simple AC powered linear power supply usually uses a transformer to convert the voltage from the wall outlet (mains) to a different, usually a lower voltage. If it is used to produce DC a rectifier circuit is employed either as a single chip, an array-of diodes sometimes called Bridge Rectifier, both for forward rectification or a single diode yielding a half wave (pulsating) output. Filter is also used to remove the pulsating output of rectifier and voltage regulator is used to regulate the power supply.

Finally, depending on the requirements of the load, a linear regulator may be used to reduce the ripple sometimes also allowing for adjustment of the output to the desired but lower voltage. In the simplest case a single diode is connected directly to the mains and uses a resistor in series with a more or less fixed load to recharge a battery.

Switched-Mode Power Supply

A switched-mode power supply (SMPS) works on a different principle, consuming only as much power as is needed for the load. AC mains input is directly rectified without the use of a transformer, to obtain a DC voltage. This voltage is then sliced into small pieces by a high-speed electronic switch. The size these slices grows larger as power output requirements increase.

The input power slicing occurs at a very high speed (typically 10 KHz - 1 MHz). High frequency and high voltages in this first stage permit much smaller isolation transformers than are in a linear power supply. After the transformer secondary, the AC is again rectified to DC. To keep output voltage constant, the power supplies needs a sophisticated feedback controller to monitor current draw by the load.

Generation of Computer

Generation of computer

Introduction

The development of electronic computers had clearly helped to visualize the concept of computer.  The computer system has taken a big leaf forward with each technological breakthrough during the development process. The functions performed and speed of computer in continuously changing. There is great variations in size and cost and great breakthrough in hardware and software which result more and more advance computer. In depth, there are altogether six major stages in the continuous development process of the computer. These stages are called generations of computers.

1. First Generation Computers (1937-1953)

The computers developed during 1937 to 1953 are known as first generation computer. This generation is characterized by vacuum tube. Vacuum tube is electronic component for their hardware component. The size of this generation computer was very high. Following are the important features of first generation computers.

- Vacuum tubes were used for electronic and magnetic drums which were used for primary storage medium.

- Storage capacity was limited (e.g. 1 Kilobytes to 4 Kilobytes)

- The operating speed was slow. (e.g. in millisecond)

-  Large in size.

- This generation computer use low level language or machine level language.

- These computers were used for scientific calculations and record keeping.

- They produce more heat during operation.

- These computers need more electricity to work.

Three machines have been promoted at various times as the first electronic computers. These machines used electronic switches, in the form of vacuum tubes, instead of electromechanical relays. In principle the electronic switches would be more reliable, since they would have no moving parts that would wear out, but the technology was still new at that time and the tubes were comparable to relays in reliability. Electronic components had one major benefit, however: they could "open" and "close" about 1,000 times faster than mechanical switches.

The earliest attempt to build an electronic computer was by J.V. Atanasoff, a professor of physics and mathematics at Lowa state in 1937. Atanasoff set out to build a machine that would help his graduate students solve systems of partial differential equations. By 1941 he and graduate student Clifford Berry had succeeded in building a machine that could solve 29 simultaneous equations with 29 unknowns. However, the machine was not programmable, and was more of an electronic calculator.

The first general purpose programmable electronic computer was the Electronic Numerical Integrator and Computer (ENIAC), built by J. Presper Eckert and John V. Mauchly at the University of Pennsylvnia. Another new concept developed was EDVAC (Electronic Discrete Variable Automatic Computer). The main contribution of EDVAC was, the notion of stored program. EDVAC was able to run orders of magnitude faster than ENIAC. By storing instructions in the same medium as data, designers could concentrate on improving the internal structure of the machine without worrying about matching it to the speed of an external control.

Software technology during this period was very primitive. The first programs were written out in machine code, i.e. programmers directly wrote down the numbers that corresponded to the instructions they wanted to store in memory. By the 1950s programmers were using a symbolic notation, known as assembly language, then hand. Translation the symbolic notation into machine code. Later programs known as assemblers performed the translation task.

2. Second Generation (1954-1962)

In 1948-1949, scientists invented another electronic component called transistor which was used instead of vacuum tube in first generation computers. The compute using transistor as storage media are classified as Second Generation Computers. One transistor could do task.

The second generation saw several important developments at all levels of computer system design, from the technology used to build the basic circuits to the programming languages used to write scientific applications. Important innovations in computer architecture include index register for controlling loops and floating point units for calculations based on real numbers.

During this generation many high level programming languages were introduced, including FORTRAN (Formula Translation) in 1956, ALGOL (Algorithm Language) in 1958, and COBOL (Common Business Oriented Language) in 1959. Important commercial machines of this era include the IBM 704 and its successors, the 709 and 7049. The later introduced I/O processors for better throughput between I/O devices and main memory.

The second generation also saw the first two supercomputers designed specifically for numeric processing in scientific applications. The term "supercomputer" is generally reserved for a machine that is an order of magnitude more powerful than other machines of its era. Two machines of the 1950s deserve this title. The Livermore Atomic Research Computer (LARC) and the IBM 7030 (aka Stretch) were early examples of machines that overlapped memory operations with processor operations and had primitive form of parallel processing.

3. Third Generation (1963-1972)

The third generation brought huge gains in computational power. Innovations in this era include the use of integrated circuits, or ICs (semiconductor devices with several transistors built into one physical component), semiconductor memories starting to be used instead of magnetic cores, microprogramming as a technique for efficiently designing complex processors, the coming of age of pipelining and other forms of parallel processing and the introduction of operating systems and time-sharing.

The first ICs were based on small-scale integrations (SSI) circuits, which had around 10 device per circuit (or "chip"), and evolved to the used of medium-scale integrated  (MSI) circuits, which had up to 100 devices per chip. Multilayered printed circuits were developed and core memory was replaced by faster, solid state memories.

This generation computer can perform parallel processing perfectly which cause fast processing in computer system. In parallel processing, more than one process can be performed at same time. Another important feature of this generation computer was multiprocessing and multiprogramming where multiprocessing means more than one process can be process can be performed at same time by same processor where as multiprogramming means more than one programming can run at same time by same processor.

In this third generation, Cambridge and the University of London cooperated in the development of CPL (Combined Programming Language, 1963). CPL was, according to its authors, and attempt to capture only the important features of the complicated and sophisticated ALGOL. However, like ALGOL, CPL was large with many features that were hard to learn. In an attempt at further simplification, Martin Richards of Cambridge developed a subset of CPL called BCPL (Basic Combined Programming Language) in1967. In 1970 Ken Thompson of Bell Labs Developed yet another simplification of CPL called simply B, in connection with an early implementation of the UNIX operating system.

4. Fourth Generation (1972-1984)

The next generation of computer systems saw the use of large scale integration (LSI) 1000 devices per chip and very large scale integration (VLSI - 100,000 devices per chip) in the construction of computing elements. At this scale entire processors will fit onto a single chip, and for simple systems the entire computer (processor, main memory and I/O controllers) can fit on one chip. Gate delays dropped to about 1 ns (nanosecond) per gate.

During this generation computer microprocessor was developed. Microprocessor is that type of chip where AL, Control Unit and Main memory and related small memories are integrated inside single chip.

Semiconductor memories replaced core memories as the main memory in most systems; unit this time the use of semiconductor memory in most systems was limited to register and cache. During this period high speed vector processors, such as the CRAY1, CRAY X-MP and CYBER 205 dominated the high performance computing scene. Computers with large main memory, such as the CRAY 2, began to emerge. A variety of parallel architectures began to appear; however, during this period the parallel computing efforts were of a mostly experimental nature and most computational science was carried out on vector processors microcomputers and workstations were introduced and saw wide use as alternatives to time shared mainframe computers.

Developments in software include very high level languages such as FP (Functional Programming) and Prolog (Programming in logic). These languages tend to use a declarative programming style as opposed to the imperative style of Pascal, C, FORTRAN, etc. two important events marked the early part of the third generation: the development of the C programming language and the UNIX operating system, both at Bell Labs. In 1972, Dennis Ritchie, seeking to meet the design goals of CPL and generalize Thompson's B, developed the C language. Thompson and Ritchie then used C to write a version of UNIX for the DEC-11.

5. Fifth Generation (1984-1990)

The development of the next generation of computer systems is characterized mainly by the acceptance of parallel processing. Until this time parallelism was limited to pipelining and vector processing, or at most to a few processors sharing jobs. The fifth generation saw the introduction of machines with hundreds of processors that could all be working o different parts of a single program. The scale of integration in semiconductors are continued at an incredible pace - by 1990 it was possible to build chips with a million components and semiconductor memories became standard on all computers.

Other new developments were the widespread use of computer networks and the increasing use of single-user workstations. Prior to1985 large scale parallel processing was viewed as a research goal, but two systems introduced around this time are typical of the first commercial products to be based on parallel processing.

Computer network is another new concept used in this generation computer. Computer network means connection of computer with each other to exchange information and to share the resources.

Intel connected each processor to its own memory and used a network interface to connect processors. This distributed memory architecture meant memory was no longer a large systems (using more processors) could be built. Toward the end of this period a third type of parallel processor was introduced to the market. In this style of machine, known as data-parallel or SIMD, there are several thousand very simple processors. All processors work under the direction of a single control unit; i.e. if the control unit says 'add a to b" then all processors find their local copy of a and add it to their local copy of b.

Scientific computing in this period was still dominated by vector processing. Most manufactures of vector processors introduced parallel models, but there were very few (two to eight) processors in this parallel machine. In the area of computer networking, both Wide Area Network (WAN), Local Area Network (LAN) technology developed at a rapid pace, stimulating a transition from the traditional mainframe computing environment toward a distributed computing environment in which each user has their own workstation for relatively simple tasks (editing and compiling programs, reading mail) but sharing large, expensive resources such as file servers and supercomputers. RISC (Reduced Instruction Set Computer) technology ( a style of internal organization of the CPU) and plummeting costs for RAM brought tremendous gains in computational power of relatively low cost workstations and servers. This period also saw a market increase in both the quality and quantity of scientific visualization.

6. Sixth Generation (1990-)

Transitions between generations in computer technology are hard to define, especially as they are taking place. Some changes, such as the switch from vacuum tubes to transistors, are immediately apparent as fundamental changes. But others are clear only in retrospect. Many of the developments in computer systems since 1990 reflect gradual improvements over established systems, and thus it is hard to claim they represent a transition to a new "generation", but other developments will prove to be significant changes.

This generation is beginning with many gains in parallel computing, both in the hardware area and in improved understanding of how to develop algorithms to exploit diverse, massively parallel architectures. Parallel systems now complete with vector processors in terms of total computing power and most expect parallel systems to dominate the future.

Workstation technology has continued to improve, with processor designs now using a combination of RISC, pipelining, and parallel processors. As a result it is now possible to purchase a desktop workstation for about $30,000 that has the same overall computing power (100 megaflops) as fourth generation supercomputers. This development has sparked an interest in heterogeneous computing: a program started on one workstation can fine idle workstations elsewhere in the local network to run parallel subtasks.

The expected features of computers are natural language processing, artificial intelligence, problem solving techniques, pattern recognition and speech recognition.

Application of Computer

 Role of Computer in Modern Society

 

Computer in Education:- Due to fast growing technology on computer and internet, the computer become most useful in the field of education and learning. The computer can play vital role of teacher, teaching material and student. The concept of online teaching is most popular technology. The computer can be used in school, campus, and any type of educational organizations. The teacher can prepare the note by using computer. Student can search the educational materials from internet. For example if we want to know about hard disk we can search its related files and material from internet. The following are the useful technology used in education.

             Online education:- Now a days, the student can study from internet in online that means the student and teacher can share the information at a same time. This process can also be applicable for evaluation of students. Here, student can give exam in online.

           

             Remote education system:- In this system, student and teacher are not together the teacher can teach remote student and student can learn from remote distance.

                       Educational materials:- The computer can be educational material itself. Computer can be used for presentation, learning, watching educational movies etc. through the use of computer we can prepare the education materials like video files, audio files, presentation files etc.

Computer in Industries:- Different types industry can use computer for their test, research and business purpose. To communicate with other industry, to communicate the new technology in product, the industry can use computer and internet. For example, a chemical industry can use computer for their chemical test, an automobile industry can use computer to check different configuration of parts, to make drawing. In this way any type industry can use computer to keep records about employees, customers, raw materials, products etc.

Computer in Transportation:- online ticket reservation system is most famous term used in transportation. In online ticket reservation system the customer can book the ticket in online that means he/she can book the ticket even from home or anywhere. The customer should not go to ticket counter. This technology is applicable in any type of transportation system like bus, plane, ship etc. now only reservation system, the computer can also be used to keep the record, to calculate any necessary calculations etc. to share the information between different organizations etc the computer is useful.

Computer in Research:- Computer is usable for astronomy to research about planets. In this way computer can also be use in research in healthcare to research about any disease. Educational research also use computer for their work, as well as to keep records. Another use of computer in research is to view to image from remote distance. From image of any object we can easily study about that object. In this way, we can take photo of any object for their study as well as video.

Computer in Commercial Purpose:- Now a days, business has also become highly electronics. Thus, use of computer has greatly impact on modern business. People find virtual shopping malls, virtual show rooms etc. internet and computer greatly facilitated the business in today's modern context. Following are the related term in modern business.

                  E-commerce:- Its stands for electronic commerce. Here, selling and buying can be done by sing computer and internet. Paying bill, getting goods can be done in online that means from resident, no need to go to shop.

               Online booking:-Booking of materials, booking of seats, etc can be done from internet from resident is called online booking. This is also important technology used in business.

              Online banking:-Here, money can withdraw and deposit in bank in online. The information can share from internet and directly the account can be transfer from one person to another. Here, all the information are kept in computer and in online in related fields.

               Online shopping:- Shelling and buying in online is known as online shopping. In this system, the customer is in his/her resident and he/she should have internet to view the information about goods in online. And customer can select the goods in online. That information will go to shopkeeper, and he can sent goods to his/her resident and receive money from his/her bank account.