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submitted by Harshit (5 m) on 31 Aug 2012 14:48:44 IST
One of the most interesting non-programming parts of computer science is the study of what can (and cannot) be computed. For instance, take the question, "does this program complete?" I.e., will it not go into an infinite loop. How would you answer this question, given an arbitrary piece of code? You could try running it. But what if it takes a long time? How long are you willing to wait? Think about whether there is a general solution to this problem -- a method that you could apply to any piece of C code in order to demonstrate that it will eventually come to a stop.Let's say that you discovered such a solution. It's a program that takes two argu
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submitted by Aarav (0 m) on 31 Aug 2012 14:45:07 IST
Algebra is a profound subject that can intimidate students at each succeeding level of difficulty. The initial difficulty is understanding just what variables are and what they mean. After you grasp this knowledge, you are confronted with increasingly difficult equations and expressions. However, there are fun ways to remember what these new symbols mean and how to use them.Fruits Of SubstitutionMany students are immediately stumped when they see variables for the first time and do not understand how to add them, multiply them and make them interact with regular numbers. To get over this stumbling block, imagine that the "x" in "x + 3" is really
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submitted by Garima (0 m) on 31 Aug 2012 14:34:21 IST
Most algorithms we have studied so far have polynomial-time running times. According to Cormen, Leiserson, and Rivest, polynomial-time algorithms can be considered tractable for the following reasons. (1) Although a problem which has a running time of say O(n20) or O(n100) can be called intractable, there are very few practical problems with such orders of polynomial complexity. (2) For reasonable models of computation, a problem that can be solved in polynomial time in one model can also be solved in polynomial time on another. (3) The class of polynomial-time solvable problems has nice closure properties (since polynomials are closed under addition, multiplic
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submitted by Sandeep (0 m) on 31 Aug 2012 14:31:24 IST
An algorithm is said to be polynomially bounded if its worst-case complexity is bounded by a polynomial function of the input size. A problem is said to be polynomially bounded if there is a polynomially bounded algorithm for it.P is the class of all decision problems that are polynomially bounded. The implication is that a decision problem X P can be solved in polynomial time on a deterministic computation model (such as a deterministic Turing machine).NP represents the class of decision problems which can be solved in polynomial time by a non-deterministic model of computation. That is, a decision problem X NP can be solved in polynomial-time on a non-
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submitted by Bhavesh (0 m) on 31 Aug 2012 14:26:15 IST
A Turing machine is a theoretical computing machine invented by Alan Turing (1937) to serve as an idealized model for mathematical calculation. A Turing machine consists of a line of cells known as a "tape" that can be moved back and forth, an active element known as the "head" that possesses a property known as "state" and that can change the property known as "color" of the active cell underneath it, and a set of instructions for how the head should modify the active cell and move the tape (Wolfram 2002, pp. 78-81). At each step, the machine may modify the color of the active cell, change the state of the hea
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submitted by Bhavesh (0 m) on 31 Aug 2012 14:15:11 IST
Type 0: Unrestricted rewriting systems. The languages defined by Type 0 grammars are accepted by Turing machines; Chomskyan transformations are defined as Type 0 grammars. Type 0 grammars have rules of the form where and are arbitrary strings over a vocabulary V and . Type 1: Context-sensitive grammars. The languages defined by Type 1 grammars are accepted by linear bounded automata; the syntax of some natural languages (including Dutch, Swiss German and Bambara), but not all, is generally held in computational linguistics to have structures of this type. Type 1 grammars have rules of the form B where , , , or of the form , where is the initial
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submitted by Vaibhav (0 m) on 31 Aug 2012 13:48:29 IST
Mastering matrices can be frustrating for any arithmetic student. Between setting them up appropriately and actually solving them accurately, the whole process can be adequate cause for feelings of confusion. However, as with most mathematical concepts, enduring the process of learning them can be made much more enjoyable when one knows exactly how the calculations can be used to benefit common day life. Learning about matrices is no different, and fortunately the concepts behind matrices are actually regularly applied in everyday life.Calculating the Area of a TriangleWhile the area of a triangle can conveniently be calculated when the triangle is a right triangle,
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submitted by Jayesh (0 m) on 31 Aug 2012 13:46:20 IST
To connect analogue circuits together there are three basic methods, Direct Coupling, Capacitive Coupling and transformer coupling. All have different properties and can be used in any linear or non-linear circuit.Direct CouplingWith direct coupling, or DC coupling, two components are connected directly to each other. In the diagram, the collector of Q1 is wired direct to the base of Q2. The bias level of Q1 is calculated first, and this will also be the bias for the base of Q2. The advantages are, minimum parts and a good low frequency response, down to dc.Capacitive CouplingWith capacitive coupling, two stages are connected using a coupling capacitor,Cc in the dia
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submitted by Isha (0 m) on 31 Aug 2012 13:44:19 IST
The node voltage method of analysis solves for unknown voltages at circuit nodes in terms of a system of KCL equations. This analysis looks strange because it involves replacing voltage sources with equivalent current sources. Also, resistor values in ohms are replaced by equivalent conductances in siemens, G = 1/R. The siemens (S) is the unit of conductance, having replaced the mho unit. In any event S = Ω-1. And S = mho (obsolete).We start with a circuit having conventional voltage sources. A common node E0 is chosen as a reference point. The node voltages E1 and E2 are calculated with respect to this point.A voltage source in series with a resista
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submitted by Radhika (5 m) on 31 Aug 2012 13:23:16 IST
The Mesh Current Method, also known as the Loop Current Method, is quite similar to the Branch Current method in that it uses simultaneous equations, Kirchhoff's Voltage Law, and Ohm's Law to determine unknown currents in a network. It differs from the Branch Current method in that it does not use Kirchhoff's Current Law, and it is usually able to solve a circuit with less unknown variables and less simultaneous equations, which is especially nice if you're forced to solve without a calculator.Mesh Current, conventional methodLet's see how this method works on the same example problem:The first step in the Mesh Current method is to iden
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submitted by Anisha (0 m) on 31 Aug 2012 13:10:27 IST
The asymptotic form of the -step Bernoulli distribution with parameters and is given by (Papoulis 1984, p. 105).Uspensky (1937) defines the de Moivre-Laplace theorem as the fact that the sum of those terms of the binomial series of for which the number of successes falls between and is approximately where
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submitted by anu (0 m) on 31 Aug 2012 12:41:47 IST
, Due to the time shifting property, we also have , , Due to the scaling in z-domain property, we have Applying the property of differentiation in z-Domain to the above, we have , , Applying the scaling in z-domain property to , we have and similarly, we have Moreover, we have
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submitted by Kaavya (0 m) on 31 Aug 2012 12:39:43 IST
A signal is a time-varying quantity. Signals are often graphed showing how this quantity varies with time. Signals are important in In the field of electronics, communications engineering and systems engineering. Continuous-time signals can occupy any real number value along the time axis. Continuous-time signals are contrasted with discrete-time signals, which occupy only countable numbers along the time axis.PeriodicityContinuous-time signals can be periodic or nonperiodic. Periodic signals repeat themselves after a certain length of time. This period of time is called the period of the signal and is usually denoted with a "T." Nonperiodic signals do not
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submitted by Nitin (0 m) on 31 Aug 2012 12:37:12 IST
The z-transform has a set of properties in parallel with that of the Fourier transform (and Laplace transform). The difference is that we need to pay special attention to the ROCs. In the following, we always assume and Linearity While it is obvious that the ROC of the linear combination of and should be the intersection of the their individual ROCs in which both and exist, note that in some cases the ROC of the linear combination could be larger than . For example, for both and , the ROC is , but the ROC of their difference is the entire z-plane. Time Shifting Proof: Define , we have
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submitted by Bharati (65 m) on 31 Aug 2012 12:17:20 IST
Stepper motors are an integral part of computer drives, robotics and even rotating antennas. With the proper software configuration, you can control how a stepper motor interacts with the attached device. With the right manual you can install a stepper motor into the device. It is important to understand the purpose of the different wires, the interfacing with the software, and the amount of power you will require to operate efficiently. Stepper motors vary according to the purpose and the manufacturer.The FactsA stepper motor is a small motor that operates by moving in small increments, not a continuous motion like other motors. As the motor inches around, it moves
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submitted by Harshit (5 m) on 31 Aug 2012 12:15:33 IST
Mathematical modeling is an area of applied mathematics that focuses on studying mathematics of the real world. It uses known mathematical concepts from physics, differential equations and analysis to examine real life systems such as traffic congestion, biological diversity and financial economics. The language of mathematical modeling can be applied to a variety of scientific disciplines including psychology, political science, physics, engineering, sociology and computer science.The FactsModels are important to the understanding of many scientific concepts and ideas. Individuals have devoted a great amount of time time to building and improving on existing models
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submitted by Sumit (0 m) on 31 Aug 2012 12:14:09 IST
Frequency response and impulse response are used to understand the dynamics of various systems. Such systems may include audio, signal processing systems, control systems, planetary systems or even economic systems. Frequency response and impulse response are interrelated; however, they often have different applications and purposes. For example, with audio signals you can use an impulse input to measure a frequency response in decibels. With impulse response, however, the applications are much wider when applied to more-advanced systems such as planetary motions.Definition of Frequency ResponseFrequency response is used to understand how to control a system. Part o
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submitted by Mohit (5 m) on 31 Aug 2012 12:12:43 IST
There are two types of control systems namely:1. Open loop (feedback )2. Closed loop (non-feedback)Open loopIf in a physical system there is no automatic correction of the variation in its output, it is called an open loop control system. That is, in this type of system, sensing of the actual output and comparing of this output (through feedback) with the desired input doesn't take place. The system on its own is not in a position to give the desired output and it cannot take into account the disturbances. In these systems, the changes in output can be corrected only by changing the input manually.These are simple in construction, stable and cost cheap. But thes
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submitted by Aadesh (0 m) on 30 Aug 2012 18:11:23 IST
Understanding The Concept Of Linear ProgrammingBy Umesh Kumar MLinear programming is an operations research technique which originated during the early 1950s. Having diverse practical applications, the technique has benefitted immensely various organizations in their production and other operations. Prof. G.B. Dantzig is one of the pioneers in the formulating the procedure of Linear programming.This technique can be applied in various situations: long range planning, production planning, warehousing decisions, physical distribution decisions, marketing, and product mix decisions, fluid blending problems, exploration of oil deposits, purchasing decisions, quality con
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submitted by Sachi (0 m) on 30 Aug 2012 18:10:11 IST
Overview of Metal CastingMetal casting occurs when a metalworker pours liquefied metal into a hollow cavity and then allows the metal to cool and harden inside. The hollow cavity is the cast (or mold), and it gives the desired size and shape to the part being manufactured. The finished metal part is then ejected from the cast and polished. Metal casting is used to make complex or highly customized metal parts that would be difficult or expensive to manufacture through other means, such as machining, forging, welding or rolling.The Metal Casting ProcessMolten MetalThe first step in the metal casting process is to obtain the necessary mold. Metalworkers generally send
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