Cyberterrorism Essay Example for Free

Cyberterrorism Essay The term cyberterrorism was created in the mid 90’s by combining cyberspace and terrorism. The term has been widely accepted after being embraced by the United State Intelligence Community. Janczewski and Colarik describe cyberterrorism as â€Å"Premeditated, politically motivated attacks by subnational groups, clandestine agents, or individuals against information and computer systems, computer programs, and data that result in violence against non-combat targets† (Janczewski Colarik, 2005, p. 43). Cyberterrorism is a form of terrorism that uses any form of connected source to engage in attacks of information systems, incitement to violence, theft of data, and planning of terrorist attacks (Britz, 2011, p. 197). As an introduction into the topic, the following definition is key to understanding the definition: â€Å"Cyberterrorism is the convergence of terrorism and cyberspace. It is generally understood to mean unlawful attacks and threats of attack against computers, networks, and the information stored therein when done to intimidate or coercer a government or its people in furtherance of political or social objectives. Further, to qualify as cyberterrorism, an attack should result in violence against persons or property, or at least cause enough harm to generate fear. Attacks that lead to death or bodily injury, explosions, plane crashes, water contamination, or severe economic loss would be examples. Serious attacks against critical infrastructures could be acts of cyberterrorism, depending on their impact. Attacks that disrupt nonessential services or that are mainly a costly nuisance would not† (Denning, 2000). Cyberterrorism is considered an act of violence or intimidation using cyberspace. It is more complicated than simply hacking into a system to see what damage can be done; it has to stem from a motivational source such as politics, foreign government, or some other rousing source (Gross, 2003). Enemies of the U. S. are strongly motivated by hate. Hate can be a strong motivator when it comes to cyberterrorism, and just terrorism in general. When hate is the driving factor of actions, the consideration for the targeted group is very minimal, and the results of hate crimes are usually violent and gruesome acts. The FBI’s definition isn’t that far off from Denning’s. They have published three different distinct definitions of cyberterrorism: â€Å"Terrorism that†¦initiates attacks on information† – â€Å"the use of Cyber tools† – and â€Å"a criminal act perpetrated by the use of computers (Baranetsky, 2009). Most government agencies that have a response program for cyberterrorism have their own published definition of cyberterrorism. The question rises ‘why does cyberterrorism occur? ’ The answer is that the terrorist want cause specific damage to the target. There are three factors that are considered when this question is asked, the first being the fear factor. It is the most common denominator of the majority of terrorist attacks. The attackers want to create as sense of fear in individuals, groups, or societies – whomever they are targeting (Janczewski Colarik, 2005, p. 45). Perhaps a cyber example of this could be the attack of IT installations. Then there is the spectacular factor. Spectacular means that the attacks are aimed at creating direct losses or resulting in a lot of negative publicity (Janczewski Colarik, 2005, p. 45). An example of the spectacular factor at work was in 1999 when Amazon. com was closed because of a Denial of Service (DOS) attack. They suffered losses from the attack, but the worse affect was the publicity that that was received (Taylor, Calabresi, Krantz, Pascual, Ressner, 2000). The last factor is the vulnerability factor. This is simply when vulnerability of an organization is exposed (Janczewski Colarik, 2005). An example of this could be the vandalism of an organizations webpage. The importance and significance of cyberterrorism is a very debatable topic. Kim Taipale, founder and executive director for the Stilwell Center for Advanced Studies in Science and Technology Policy believes â€Å"cyberterrorism, whatever it is, is a useless term. Taipale believes that, â€Å"terrorists will use any strategic tool they can† so â€Å"cyber† terrorism is no more important then other forms (Baranetsky, 2009). The statements by Taipale are strong, and arguments could be made supporting her, and arguments could be made that go against her beliefs. It is true that terrorism is growing all over the world, and terrorists are beginning to use various outlets to threaten nations, groups, and individuals. So the case could be made stating that cyberterrorism is just an accessible outlet terrorists have, because of the access that is granted to an individual on cyberspace. In conflict with that argument is the argument that cyberspace is not monitored and policed enough, and has little to no restrictions as to what can be done in cyberspace. This is an ongoing debate that will not be discussed in this paper. Different Forms of Cyber Attacks Various types of cyber attacks are used within the terrorist aspect of cyberspace. According to the Center for Strategic and International Studies, cyberterrorism is â€Å"the use of computer networks to shut down critical infrastructure (such as energy, transportation, government operations) or to coerce or intimidate a government or civilian population† (Lewis, 2002, p. ). The most commonly used tactics used to neutralize critical infrastructure are attacks known as the Trojan horse, viruses, phishing, Denial of Service (DoS), and Direct Denial of Service attacks. The first of the types of the cyber attacks to be discussed is the Trojan horse. A Trojan horse is a computer program that conceals a harmful code. Relating to the well know tale of the Trojan horse, it allows you into a system, and then leaves an outlet that allows you to get back into the system. In essence, it is software that appears to perform one action while actually performing another (Gohring, 2009, p. 6). A Trojan horse is a program that appears harmless but hides malicious functions. The most common Trojan horse of today’s day and age is NetBus, which was used for illegally breaking into computer systems and, in particular, used to plant child pornography on computers of people of integrity. Viruses are another form of cyber attack. Viruses are programs that â€Å"infect computer files, usually executable programs, by inserting a copy of itself into the file. These copies are usually executed when the infected file is loaded into memory, allowing the virus to affect other files. A virus requires human involvement to spread† (Kuehl, 2012). Virus writers write programs that infect the systems of certain users, but needs direct involvement by the creator or another human source to spread the virus. Very similar to a virus is a worm. The worm works just like a virus, implemented into a system by a creator. The difference between a worm and a virus is the fact that a worm doesn’t need the hands-on human involvement. Back in 2003, SQL Slammer worm spread throughout the cyber world. This was a worm that exploited a buffer overflow vulnerability of Microsoft’s SQL Server. Six months prior to the launch of the worm, the vulnerability was taken notice of and a patch was developed to strengthen the vulnerability. The worm worked by generating random IP addresses, and if belonged to an SQL Server that was not covered by the patch, it was infected and immediately began sending out more copies of the worm to more random IP addresses (Leyden, 2003). There was no human involvement after the worm was created initiated by the creator. It spread itself to random IP addresses, which categorizes it as a worm. Phishing is a form of deception used in cyberspace. Phishing attempts to trick users into giving out their personal data. The techniques used in phishing attempts are emails and websites that are designed to look like legitimate agency websites asking for an individual’s bank and financial account information and passwords (Kuehl, 2012). This method is not used so much by cyberterrorists, but the possibility is there. A more serious cyber attack comes in the form of a Denial of Service (DoS) attack. DoS attacks deny system access to users by overwhelming the target source with messages and blocking legitimate traffic (Kuehl, 2012). It causes a system overload, and can block the ability to exchange data between systems using the Internet. DoS attacks usually target banks, and earlier this year in September, several major banks were attacked using DoS. The websites of Bank of America, JPMorgan Chase, Wells Fargo, U. S. Bank, and PNC Bank all were victims of a DoS attack (Goldman, 2012). The websites were overloaded with traffic directed at them causing them to crash. Most of the time while the cyberterrorists use these attacks to steal information from bank customers, but in this case the motivation was simply to temporarily take down the banks’ public-facing websites, putting them under extreme heat from the public and potentially tarnishing their reputations. There are three levels of cyber capability that need to be taken into thought when considering types of cyberterrorism attacks. The first is simple-unstructured capability. This allows a cyberterrorist to conduct basic hacks against individual systems using tools created by someone else. The organization possesses little target analysis, command and control, or learning capability (Denning, 2000). This level is sometimes not considered to be cyberterrorism, because of the simplicity of the attack. There is slight to no attention focused on the target, which does not reveal any sort of motivation. Referring back to the definition of cyberterrorism, it has to stem from a motivational source to be considered cyberterrorism (Gross, 2003). The simple-unstructured capable individuals are basically the ones who hack into systems just to see what kind of damage they can cause. The second level of capability is the advance-structured level. This is the competence to conduct more sophisticated attacks against multiple systems or networks and possibly, to modify or create basic hacking tools. The organization possesses a straightforward and uncomplicated target analysis, command control, and learning capability (Denning, 2000). These organizations have motivations, but they are not strong enough to cause serious damage to the identified target. The last capability is the complex-coordinated capability. This is the ability for coordinated attacks capable of causing mass-disruption against integrated, heterogeneous defenses. They have the capacity to create sophisticated hacking tools. There is a highly capable target analysis, command control, and organization learning capability (Denning, 2000). Organizations with this type of capability are highly sophisticated with dangerous motivations. These dangerous organizations are the ones that can cause millions of dollars of damage, and also tons of negative publicity, two of the main objectives of cyberterrorist. There are cases when terrorists actually run other forms of terrorisms, such as bombings, with the use of cyberspace. The anonymity and global reach of the Internet has helped facilitate terrorism (Cole Glasser, 2009). â€Å"They put up websites to spread their messages and recruit supporters, and they use the Internet to communicate and coordinate action. However, there are few indications that they are pursuing in cyberterrorism, either alone or in conjunction with acts of violence† (Denning, 2000). There is an example of this from the late 90’s. In February 1998, Clark Staten, executive director of the Emergency Response and Research Institute in Chicago, testified before the Senate Judiciary Committee Subcommittee that it was believed that â€Å"members of some Islamic extremist organizations have been trying to develop a network of hackers to support their computer activities in offensive information warfare attacks in the future† (Denning, Cyberterrorism, 2000). It is the perfect way to recruit, because of the anonymity that is granted to the individual. â€Å"The Internet is the ideal medium for terrorism today: anonymous but pervasive† (Cole Glasser, 2009, p. 95).

The Rayleigh Ritz Method Computer Science Essay

The Rayleigh Ritz Method Computer Science Essay The given assignment is done with the soul purpose of developing an intense knowledge and understanding of vibrational behaviour and dynamic response of structures. The assignment aims to apply up to date methods of structural dynamics in aerospace and aerospace system engineering. Here we use Rayleigh-Ritz method and Finite Element method to obtain the natural frequency and mode shape of the given cantilever beam. 1. Rayleigh-Ritz Method Rayleigh-Ritz method is an extension of the Rayleigh method which was developed by the Swiss mathematician and physicist Walter Ritz. Its one of the widely used method to calculate more accurate value of fundamental frequency, further it also gives approximations to the higher frequencies and mode shapes. In the Ritz method the single shape function is replaced by a series of shape functions multiplied by constant coefficients, that is the single function of deflection choose in Rayleigh method is assumed to be a sum of several functions multiplied by constant coefficients. The coefficients values are modified by reducing the frequency with respect to each of the coefficients, which result in n algebraic equations in. The solution of these equations will give the value of natural frequency and mode shapes of the system. It should be taken into account that the success of the method is only possible so long as the shape function taken satisfies the geometric boundary conditions of the problem. The method should also be differentiable to the order of the derivatives of the equations. Here the function can ignore discontinuities like shear due to concentrated masses that involve third derivatives in beam. The Rayleigh-Ritz method is done by assuming the deflection curve of the beam by The function are the assumed displacement functions that satisfy geometrical boundary conditions. For a cantilever beam the boundary conditions are They are selected such that it is possible to obtain a good approximation to each of the required natural modes by superposition. The quantities are generalized coordinates representing contributions of each assumed functions. For a beam divided into à ¢Ã¢â€š ¬Ã¢â‚¬ ºn span wise stations the total differential equation can be formulate using Lagrange equation as Putting as a solution , where the amplitude of the displacement is, is the frequency and is the phase angle. This set of characteristics equations can be solved for n discrete values of . This equation can easily be put into a matrix form for numerical calculation as For a beam divided into n span wise station the mass and stiffness terms can be formulated into matrices as Where = matrix of assumed modes = mass matrix = matrix of weighting coefficients = rigidity matrix Hence we write as The above equation is considered to be convenient for computation, but has limitations in the manner of expressing the strain energy. Given Data Length L=1.5 Modulus of Elasticity E=74 GPa Poissons Ratio P=0.33 Material density The depth of the beam tapers uniformly from 0.3 at the fixed end to 0.1 at the free end. The breadth of the beam tapers uniformly from 0.02 at the fixed end to 0.005 at the free end. The assumed modes are given by the polynomial function: MATLAB Operation >> L=1.5 L = 1.5000 >>x=[0,0.15,0.3,0.45,0.6,0.75,0.9,1.05,1.2,1.35,1.5] x = 0 0.1500 0.3000 0.4500 0.6000 0.7500 0.9000 1.0500 1.2000 1.3500 1.5000 >> s=x/L s = 0 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1.0000 >> V1= 2*s.^2-(4/3)*s.^3+(1/3)*s.^4 V1 = 0 0.0187 0.0699 0.1467 0.2432 0.3542 0.4752 0.6027 0.7339 0.8667 1.0000 >> V2=(10/3)*s.^3-(10/3)*s.^4+s.^5 V2 = 0 0.0030 0.0217 0.0654 0.1382 0.2396 0.3658 0.5111 0.6690 0.8335 1.0000 >> V=[V1;V2] V = 0 0.0187 0.0699 0.1467 0.2432 0.3542 0.4752 0.6027 0.7339 0.8667 1.0000 0 0.0030 0.0217 0.0654 0.1382 0.2396 0.3658 0.5111 0.6690 0.8335 1.0000 >> dV1=(1/(L.^2))*(4-8*s+4*(s.^2)) dV1 = 1.7778 1.4400 1.1378 0.8711 0.6400 0.4444 0.2844 0.1600 0.0711 0.0178 0 >> dV2= (1/(L.^2))*(20*s-40*(s.^2)+20*(s.^3)) dV2 = 0 0.7200 1.1378 1.3067 1.2800 1.1111 0.8533 0.5600 0.2844 0.0800 0 >> dV=[dV1;dV2] dV = 1.7778 1.4400 1.1378 0.8711 0.6400 0.4444 0.2844 0.1600 0.0711 0.0178 0 0 0 .7200 1.1378 1.3067 1.2800 1.1111 0.8533 0.5600 0.2844 0.0800 0 Weighting matrix can be formulated using Trapezoidal rule, Simpsons rule and Lagranges Interpolation formula. By Lagranges interpolation formula if the beam is divided into 10 equal elements with spacing à ¢Ã¢â€š ¬Ã¢â‚¬ ºd then weighting matrix is computed as: MATLAB Operation >> d=0.15 d = 0.1500 >> W1=(d/3.7266)*[1,6.616,-3.020,16.954,-16.216,26.599,-16.216,16.954, -3.020, 6.616,1] W1 = 0.0403 0.2663 -0.1216 0.6824 -0.6527 1.0706 -0.6527 0.6824 -0.1216 0.2663 0.0403 >> W=diag(W1) W = 0.0403 0 0 0 0 0 0 0 0 0 0 0 0.2663 0 0 0 0 0 0 0 0 0 0 0 -0.1216 0 0 0 0 0 0 0 0 0 0 0 0.6824 0 0 0 0 0 0 0 0 0 0 0 -0.6527 0 0 0 0 0 0 0 0 0 0 0 1.0706 0 0 0 0 0 0 0 0 0 0 0 -0.6527 0 0 0 0 0 0 0 0 0 0 0 0.6824 0 0 0 0 0 0 0 0 0 0 0 -0.1216 0 0 0 0 0 0 0 0 0 0 0 0.2663 0 0 0 0 0 0 0 0 0 0 0 0.0403 Mass matrix is a diagonal matrix representing the mass per unit length at the eleven span wise stations. The matrix can be calculated by Material density = 2700 The depth of the beam at a station with a distance x from the fixed end is given by Depth Similarly the breadth of the beam at a station with a distance x from the fixed end is given by Breadth MATLAB Operation >> h=0.3-(s*0.2) h = 0.3000 0.2800 0.2600 0.2400 0.2200 0.2000 0.1800 0.1600 0.1400 0.1200 0.1000 >> b=0.02-(s*0.015) b = 0.0200 0.0185 0.0170 0.0155 0.0140 0.0125 0.0110 0.0095 0.0080 0.0065 0.0050 >> m=2700*diag(b)*diag(h) m = 16.2000 0 0 0 0 0 0 0 0 0 0 0 13.9860 0 0 0 0 0 0 0 0 0 0 0 11.9340 0 0 0 0 0 0 0 0 0 0 0 10.0440 0 0 0 0 0 0 0 0 0 0 0 8.3160 0 0 0 0 0 0 0 0 0 0 0 6.7500 0 0 0 0 0 0 0 0 0 0 0 5.3460 0 0 0 0 0 0 0 0 0 0 0 4.1040 0 0 0 0 0 0 0 0 0 0 0 3.0240 0 0 0 0 0 0 0 0 0 0 0 2.1060 0 0 0 0 0 0 0 0 0 0 0 1.3500 The Second moment of area of the beam is given by MATLAB Operation >> I=diag(h)*(diag(b).^3)/12 I = 1.0e-006 * 0.2000 0 0 0 0 0 0 0 0 0 0 0 0.1477 0 0 0 0 0 0 0 0 0 0 0 0.1064 0 0 0 0 0 0 0 0 0 0 0 0.0745 0 0 0 0 0 0 0 0 0 0 0 0.0503 0 0 0 0 0 0 0 0 0 0 0 0.0326 0 0 0 0 0 0 0 0 0 0 0 0.0200 0 0 0 0 0 0 0 0 0 0 0 0.0114 0 0 0 0 0 0 0 0 0 0 0 0.0060 0 0 0 0 0 0 0 0 0 0 0 0.0027 0 0 0 0 0 0 0 0 0 0 0 0.0010 Rigidity matrix is the diagonal matrix that gives the product of modulus of elasticity and the second moment of area of the beam about the neutral axis. EI=74000000000*I EI = 1.0e+004 * 1.4800 0 0 0 0 0 0 0 0 0 0 0 1.0933 0 0 0 0 0 0 0 0 0 0 0 0.7877 0 0 0 0 0 0 0 0 0 0 0 0.5511 0 0 0 0 0 0 0 0 0 0 0 0.3723 0 0 0 0 0 0 0 0 0 0 0 0.2409 0 0 0 0 0 0 0 0 0 0 0 0.1477 0 0 0 0 0 0 0 0 0 0 0 0.0846 0 0 0 0 0 0 0 0 0 0 0 0.0442 0 0 0 0 0 0 0 0 0 0 0 0.0203 0 0 0 0 0 0 0 0 0 0 0 0.0077 Substituting in Rayleigh-Ritz equation: This gives Simplifying The above equation is a quadratic in , which can be solved = Result: The approximate values of the first and second natural frequencies of the given beam under flexural vibrations, by the use of Rayleigh- Ritz method, was found to be 2. Mode shapes Consider the equation Substituting the values of in the above equation and simplifying The column matrix that represents the mode shape at the eleven stations is obtained by putting, = 0.0578 Substituting the value of in the above equation and simplifying The column matrix that represents the mode shape at the eleven stations is obtained by putting, = 0.0693 3. Finite Element Method Finite Element Method (FEM) is considered to be one of the profound developments in the static and dynamics analysis of continuous systems. It provides a discrete approximation to vibration of continuous systems. The finite element method can be developed as a special case of the Rayleigh -Ritz method. The method was originally developed for the static- stress analysis of complex distributed parameter structures. Now a days FEM is widely applied to disciplines of heat transfer, electro magnetics, fluid flow and vibrations. In finite element method the structure is divided into a large number of small but finite parts called elements which are interconnected at points called nodes. For each element a displacement function is assumed which satisfies the geometric boundary condition so that continuity is achieved between the elements. The variations in displacement of each element( which can be linear, quadratic etc.), are assumed over the length of the element. This method allows the displacement of any point in the element to be expressed in terms of the displacement at the end of the element. These displacements by finite element terminology are called nodal variables. Unlike Rayleigh-Ritz in finite element method the global coordinate is replaced by a local coordinate where is the length of the element. The kinetic and strain energy of the element is obtained by integrating along the elements length, in terms of the nodal variables. By superposing the energies contributed by the individual elements into which the structure is divided, we can obtain the kinetic and strain energy of the structure or system in terms of the nodal variables of the whole structure. The finite element method is mainly based on variational principles. The method is considered very much versatile and can be used to physical problems with arbitrary shapes, loads and support conditions. The finite element model has a close resemblance to the actual structure. Many general finite element code packages have been written over the years with user friendly windows and menus (GUI) which allow for easy geometry setup, boundary condition manipulation and evaluation/post processing of common structural problems. Some of the most popular codes in the industry are ANSYS, MSC Nastran and MARC. ANSYS will be the code used for this assignment. ANSYS Operation Define Material Step 1: Set preferences Preferences are set in order to filter quantities that pertain to this discipline. Step 2: Define constant material properties. Modulus of elasticity, Poissons ratio and Density are defined. Step 3:- Modeling Create the beam with required geometry. Generating Mesh Step 4: Define element type Two element types are defined: a 2-D element and a 3-D element. The beam cross-sectional area is meshed with 2-D elements, and then the area is to be extruded to create a 3-D volume. The mesh will be extruded along with the geometry so 3-D elements will automatically be created in the volume. Step 5: Mesh the area Mesh control are specified in order to obtain a particular mesh density. Element edge length is set at 0.01 Note: Mesh density is very important. If the mesh is too coarse your result can contain serious errors. If the mesh is too fine, would cause waste of computer resources, experience excessively long run time, the model may be too large to be run on the computer system. Unfortunately it cannot be definitively specified how fine the mesh density should be. But one way to find out is to perform the analysis with what seems to be a reasonable mesh. Then reanalyse the problem with twice as many elements in the critical region and compare the results. If the two mesh give the same result then the mesh probably be adequate. If there is substantial difference between the two results then further refinement of the mesh is required. Step 6:- Extrude the meshed area into a meshed volume. The 3-D volume is generated by first changing the element type to SOLID 45, which is defined as element type 2, and then extruding the area into a volume. The number of element divisions is set as 10 Offsets of extrusion are set as 0, 0, 1.5 Tapering ratio is given as 0.33333, 0.25, 0 Apply loads Step 7:- Unselect 2-D elements Before applying constraints to the fixed end of the wing, unselect all the PLANE42 elements used in the 2-D area mesh since they will not be used for the analysis. Step 8:- Apply constraints to the model Constraints will be applied to all nodes located where the wing is fixed to the body. Select all nodes at z = 0, then apply the displacement constraints. Obtain Solution Step 9:- Specify analysis type and options Specify a modal analysis type. Number of modes to be extracted is given as 5 Number of modes to be expanded is given as 5 Step 10:- Solve Observe results Step 11:-List natural frequencies ***** INDEX OF DATA SETS ON RESULTS FILE ***** SET TIME/FREQ LOAD STEP SUBSTEP CUMULATIVE 1 11.964 1 1 1 2 40.840 1 2 2 3 100.05 1 3 3 4 144.08 1 4 4 5 182.70 1 5 5 Step 12:- Animate the two mode shapes. Set the results for the first mode to be animated. Observe the first mode shape. Animate the next mode shape. Observe the second mode shape. Repeat the same procedure to obtain the other three mode shapes. First Mode Shape Second Mode Shape Third Mode Shape Fourth Mode Shape Fifth Mode Shape 4. Comparison of Rayleigh-Ritz Method and Finite Element Method Rayleigh-Ritz method Rayleigh-Ritz method uses the principle of conservation of energy to formulate the matrix equation.one major advantage of this method is that it allows us to neglect the non-applied forces like forces at a point of rolling contact, forces at frictionless guides etc. Considering the method to be an extension of the Rayleigh method it has an improved accuracy by assuming the deflection curve of the beam to be Nevertheless the assumed function should satisfy all the boundary conditions and should be linearly independent. This can be easily achieved by using polynomial expression to derive the deflection function. Disadvantages and limitations The selection of assumed deflection function requires a good knowledge and expertise of the method Good approximation of the true natural modes are only possible as the assumed function are limited in numbers and nature All n modal solutions will not give a good approximation to the true mode, so it is necessary to discard some higher frequency modes. The approximations are only good for lower modes and it becomes worse for higher modes. The major limitation of this method is in the manner in which the strain energy can be expressed. Finite Element Method The finite element method (its practical application is often as Finite Element Analysis)is a powerful technique developed in the analysis of complex structural mechanics. In this method the structure is divided into large number of finite parts or elements which are interconnected at points called nodes. The elements will have properties like thickness, Youngs modulus, Poissons ratio etc. An assumption is made over the variation over the length of the element. This allows to find the displacement at any point in the given structure by introducing Disadvantages and limitations The method is not considered convenient for simple structures. Its a time consuming operation. Its accuracy depends on the number of elements the structure is divided. It does not provide a closed-form solution, denying analytical study of the effects of changing parameters. It needs a reliable program for support. Creating a good model requires experience. A good amount of data are required and voluminous output must be sorted and studied. Comparison of results Obtained by Rayleigh-Ritz Method Obtained by Finite Element Method % Difference 0.77% 26.82% There is difference of 26.82% for the second frequency of the system. The value obtained by the Rayleigh-Ritz method can be brought closer to accuracy by increasing the number of assumed functions and by improving their nature. Normally the approximation becomes worse as we move to higher modes .With use of only two assumed functions, the solutions obtained are considered to be satisfactory. Errors in Rayleigh-Ritz method To use the method with ease the assumed functions are kept as simple as possible by using simple polynomial functions and at fewer times only the functions of sine and cosine are used. There is no exact answer as to which function the good approximate value can be obtained. There are always some terms omitted in the function which results to an ineffective solution. This method is considered to be inflexible as the actual displacement of the structure is restricted to only the shape generated by superposing the finite number of functions selected by the analyst. Recommendation to improve Rayleigh-Ritz method The iterative process can be carried out with each time adding the term in the assumed function until it gives the exact value. Errors in Finite Element method Distorted mesh can result in flawed stiffness and mass terms Errors are always presented at joints and constrained boundaries due to uncertainty. Recommendation to improve Finite Element method Iterative method has to be applied to see the number of elements actually required to break down the structure so as to obtain more accurate value. Appropriate methods should be employed for remeshing like HYPERMESH, Mesh++ based on a posterior error. CONCLUSION The first and second natural frequencies of the given beam are found out by using both Rayleigh-Ritz method and Finite element method, and mode shapes for these frequencies are drawn.

Funny :: essays research papers

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Puritan Hypocrisy Exposed in Nathaniel Hawthornes The Scarlet Letter E

Puritan Hypocrisy Exposed in The Scarlet Letter   Ã‚   Throughout The Scarlet Letter, Hawthorne repeatedly portrays the Puritanical views of sin and evil.   The Puritans are constantly displayed as believing that evil comes from an unyielding bond being formed between love and hate.   For such reasons they looked towards Hester's commitment of adultery as an action of pure, condemned evil.   However, through the use of light and dark imagery, Hawthorne displays who truly holds evil in their hearts.   The one who is the embodiment of evil creates hypocrisy of Puritanical views towards sin and evil.   Hawthorne displays that those who expose sin to the public and the daylight are the most pure and those who conceal their sin under a dark shadow are destined to be defeated.   Through his use of light and dark imagery and the contrast of his beliefs versus the beliefs of the Puritans, Hawthorne exposes the hypocritical beliefs of the Puritans by portraying Dimmesdale as destined for demise for concealing his sin, and ironically Hester the most pure for admitting her sin.   Ã‚  Ã‚   The first description of Dimmesdale that Hawthorne presents to the reader is of Dimmesdale hiding his sin.   One Puritan says, speaking of Hester's sin, "Reverend Master Dimmesdale, her godly pastor, takes it very grievously to heart that such a scandal have come upon his congregation" (38).   Immediately, Dimmesdale is shown to the readers as not only concealing his sin, but also being hypocritical in his condemnation of a sin that he himself has also committed.   On the very same page, Hawthorne speaks of the "dismal severity of the Puritanic code of law" (38).   From the beginning of The Scarlet Letter, Hawthorne uses dismal, a dark and evil ... ... thing that frees one of evil and shame is revealing his sin.   Hawthorne foreshadows the death and demise of Dimmesdale from the beginning of the book by keeping him cast in a dark shadow with an aching heart.   Hester was continuously condemned for her sin, although it was revealed through the light constantly burning upon her chest.   This illustrates the hypocrisy of the Puritan beliefs towards sin, for it was he who concealed his sin that was destined to be defeated by his ignominy, and she who was explicitly condemned that prospers and grows and is able to live a full, didactic life.    Sources Hawthorne, Nathaniel.   The Scarlet Letter.   New York: Penguin Putnam Inc., 1980. Bradford, William.   "The Errand of the Early Puritans."   Class handout.   March 2002. Winthrop, John.   "Life in Puritan New England."   Class handout.   March 2002.

Stanlislovskis System: Concepts On Acting :: essays research papers

Stanlislovski's System: Concepts on Acting The Elements of Style, as described by Sonia More in her simplified view of the Stanlislavski System, are clear rudimentary concepts designed to help actors achieve a profound and truthful portrayal of their character on the stage through personal connection with their character. These concepts are designed as tools for the actor so that he may connect to a character or situation on the stage that he otherwise would not be able to connect with. As Sonia Moore put it, Stanlislovski knew that an actor's mind, will, and emotions must participate in the creation of a live human being on the stage. He also understood that it is impossible for people to turn their thoughts and emotions on and off as if by a switch. He also knew that no actor coming on stage without any reason for experiencing emotions would be unable to do so without some connection, or bridge, to the personal and emotional response of their character. So Stanlislovski designed tool for the actor to use to help him connect with the emotional and physical world of his character. Such concepts as The Magic If is a clear example of a tool an actor could use to connect himself the life of the character. The Magic If, simply guides the actor to ask the simple question: "What would I do if I were in my character position?" By asking this question of himself the actor can personalize the given circumstances of the character. The situation of the character becomes more personal, and the stakes much higher, because the actor has divulged some particular issues of himself into the character. Due to these particularities the actor will work out the given circumstance of the character in a much more truthful manner. Even in acting the old saying goes: "You cannot really know someone until you walk a mile in their shoes." This concept of The Magic If also plays a big part in another Element of Action -Imagination. Imagination is another tool that allows the actor to build a substantial relationship with his character by creating the very universe in which his character resides. Through this artistic imagination the actor can create the past, present, and future of the character. The actor, in essence, could play God wherein the character is concerned apart from given circumstances or the circumstances that exist within the play. This artistic imagination is being used to give thoughts and feeling to the character being portrayed by simply infusing honesty and truthfulness into the actor's performance. There are other Element's of Actions that guide the actor to form

400 Blows- French film

The French film, The 400 Blows, directed by Francois Truffaut, is about a troubled young boy named Antoine Doinel, who attempts to find meaning in his life because he has not been given the acceptance and respect for who he really is, which would enable him to become his real self. Antoine gains a sense of mistrust of his mother when he sees her kissing another man, cheating on Antoine’s stepfather, which compromises their relationship.Antoine’s main motive in the film is to find true value in his life, but he loses his desire to strive for a career as a writer after his teacher humiliates him for plagiarizing Balzac, and he realizes that his mother’s offer to give him 1,000 francs if he gets a good grade on his paper is merely a bribe to keep him from telling his stepfather about her affair. In the film, Antoine is shown as a troubled boy who is not being raised well by his mother.Since Antoine was born to an uncaring mother, he cannot be blamed for the choices he makes. Antoine’s mother doesn’t accept who Antoine is because she never wanted Antoine to exist in the first place, which is why she has no respect for Antoine from the start. When Antoine’s mother is introduced in the film, she treats Antoine as if he was nothing more than an inferior child and a mistake.Antoine’s mother doesn’t play her role as an accepting mother because she doesn’t give Antoine any guidance; therefore she prevents Antoine from becoming the person he wants to be. In the scene where Antoine and Rene skip school, Antoine sees his mother making out with another man; therefore he gets the impression that his mother is not true to the family. It triggers Antoine’s mistrust for his mother. Afterwards, his mother decides to be deceptive toward Antoine by bribing and act kind towards him in order to get him not to talk about her affair.Although his mother is nice to Antoine for the first time in the film, giving Antoine noble advice, Antoine isn’t surprised by the mother’s new behavior because he knows what his mother is trying to do, as we can see by the look of his eyes when she is talking to him. Antoine, feeling that he has to do well on the essay, decides to read a story by Balzac and for the first time he is motivated by what he’s reading about. For Antoine, it was a way for him to discover who he really is by reading one of Balzac’s works.Antoine is inspired by Balzac’s line, â€Å"Eureka, I‘ve found it,† so he decides to place a picture of Balzac in a cabinet and light a candle by the picture, suggesting his admiration for Balzac. In class, Antoine has an assigned essay to write about and he chooses to copy Balzac’s work, which he believed offered him a chance to succeed as a writer and possibly live a better life since he was concentrating on his school work for once like his mother expected him to, after the deal they made.Later, whi le Antoine was having dinner with his parents, they discovered that the cabinet where Antoine placed the candle under the picture of Balzac was on fire. The cabinet going on fire signified Antoine’s ability to be â€Å"blindsided† because his stepfather questioned why he would light the cabinet on fire. At class the teacher decides to embarrass Antoine for plagiarizing Balzac’s work, which tarnishes all of Antoine’s hard work, even his will to succeed. Furthermore, since Antoine couldn’t get a good grade on his essay like he agreed with his mother, his path to criminal behavior began.From there, Antoine knew that his parents would now want his future to be in the military because his life wasn’t going anywhere. All Antoine wanted was just to see the ocean, he tells Rene. The ocean is symbolic of life. Now that there was no turning back for Antoine, his increasing criminal behavior leads him to the Observation Center, where his path to succes s fades. Antoine accepting the bribe and the humiliation he received in class prevented him from becoming a better person and shaping his own character.Antoine loses what he wants to achieve because of his mother trying to bribe him and his teacher for degrading Antoine’s character. Although he did plagiarize Balzac’s work, he still made an attempt to focus on his schoolwork even though he didn’t do well on his essay. Antoine’s opportunity to self-actualize fails because of his mistreatment he receives from his mother and his teacher. If only his mother supported Antoine’s work, he would’ve had the confidence to stay strong and succeed.

Digital and Analog TV Essay

On February 17, 2009, the Congress of the United States mandates the full shift to digital television transmission. The law is perceived to bring several benefits to the US viewing public. Broadcast frequency bands will be available mainly for public safety purposes, for example, police and fire department concerns. Remaining portions of the old TV broadcast spectrum can be offered for technologically advanced applications such as wireless broadband. The use of digital-capable television sets allows American viewers more choices of what programs to watch, since digital broadcasts can accommodate so much more programs (Federal Communications Commission, 2008). The law is not expected to be received openly by the television viewing public, 100 percent. Since it leaves them no choice but to convert millions of TV sets from analog to digital and give up the true fidelity that analog audio signals offer. This paper aims to point out the differences of digital and analog TV. By doing so, advantages and disadvantages of each can be compared and the individual viewer can make a better choice. Robert Silva (2008) lists differences between analog TV and Digital TV. He says these these differences lie mainly in the manner of transmitting broadcasts, signal content within a bandwidth in the broadcast spectrum, and the ability to broadcast in widescreen (16Ãâ€"9) format. Transmission Analog television transmission is based on and started after World War II with black and white broadcasts. It complied with the US analog TV standard known as NTSC. After several years, color broadcasting was introduced and accommodated under the NTSC system. The video is transmitted through the AM radio band while audio is transmitted through the FM band. The reception quality depends on the distance from the television station transmitters and obstacles in between. The farther away from the transmission station the TV reception is more prone to ghosting and other video disturbances. Although analog transmission can accommodate all the technicalities of high fidelity reception, the assigned bandwidth to a television channel restricts and limits broadcast quality. Digital TV is based on modern digital technology. It was designed for BW and color broadcasts as well as audio. It handles information in the same manner as computers: on (with a binary value of â€Å"1†) or off (with a binary value of â€Å"0†). Digital broadcasts allow viewers to see uniform reception quality regardless of the distance from the transmitter. Either the digital television receives the broadcast or the TV screen remains blank (it does not receive anything at all). Signal Content Digital TV broadcasts can accommodate complete video, audio, and other information signals within the same bandwidth. Furthermore, digital television can accommodate advances in technology like High Definition (HDTV) signals. In contrast, analog TV broadcast can only send limited traditional video signals. Format The development of wide screen format programming allows the broadcast of the 16Ãâ€"9 format. Today, widescreen LCD television are getting more popular; but still expensive. It offers the advantage of portraying on the TV screen wide footages of events without the camera lens distortion caused by distances. Furthermore, the widescreen image occupies the whole digital television screen. On the other hand, analog television sets will show widescreen images with portions on top and below blacked out. The widescreen format may not be important to the regular TV viewer. For millions of television watchers, the old analog screen is good enough. Conclusion Paul Wotel (2008) gives an objective assessment of the advantages and disadvantages of both digital and analog television. Some people may opt for the old traditional analog equipment such as phones while others prefer the cordless digital phones. If you want sound fidelity, he recommends the old phones. For more advanced applications, such as the PABX systems, he recommends a digital system. The same reasoning may be applied to television sets. However, the present situation requires new priorities which did not exist before. Today, there is much concern on security and priority is given to police and fire department communications. By requiring television stations to convert to digital transmission, most of the broadcast bandwidth can be assigned to security applications. The advantages of digital television allow the viewing public to benefit from the information age we find ourselves in. Digital television can also take advantage of the internet which has become part of the lives of many, particularly the young generation. Considering the continuing evolution in information and entertainment technology we just have to follow the trend – out with old, in with the new.