Porters 5 Forces Essay Example for Free

Porters 5 Forces Essay 1) New Business / Threat of New Entrants Changing Conditions in PESTEL, Product, Service differences, brand identity, access to distribution, necessary resources, learning curve, inertia of existing markets. Expected retaliation, switching requirements, scale economics and experiences. Capital requirements. Example: Upcoming smartphone known as the OnePlus One from a completely new firm. Cheaper than other firms such as Samsung, Apple and HTC but the quality is just as good, if not better. http://www.cnet.com//oneplus-one-to-hit-general/ 2 + 3) Bargaining Power of Suppliers and Customers Concentration Number of Buyers, Switching costs esp Relationships, Control of information, Forward and backward integration, threat of Vertical integration, availability of substitutes. Importance to others performance. Brand identity, marketing and purchasing incentives. Alliances, relationships and expectations. The ability of suppliers to change the firms performance. Eg Samsung has increased costs now that their suppliers went on strike. http://www.clb.org.hk//workers-samsung-supplier-china Likewise the same thing refers to consumers, but I cant of an example off the top of my head. 4) Threat of Substitutes Sideways competition, Comparative price/performance, backing by rich competitor. Comparative technological life cycle. Benefits no product features. Theres tons of substitute products in the smartphone industry of all ranges in price and quality, so that one is self explanatory. 5) Rivalry amongst Competitors Aside from the other four forces, the nature of rivals also determine the intensity and degree of rivalry. Competitors with different values, vision,  mission, strategy and operational effectiveness, combined with different perceptions and abilities of their senior managers will influence not only the degree of competition but also its patterns. The intensity of competition is also elevated when; there are severally equally strong players such as Samsung vs Apple Few chances for differentiation They all know whats coming up and they all copy each other. Galaxy Gear, Moto 360, Apple iWatch (Rumored)

Fame in Cinema and Television Essay Example for Free

Fame in Cinema and Television Essay The â€Å"star phenomenon† began in theatrical advertising of certain actors’ names in the 1820s. It was not immediately transferred to Hollywood, nor to the many other film industries developing in parallel across the glove. Hollywood studios at first, from about 1909 to 1914, ignored â€Å"stars† – actors in whose offscreen lifestyle and personalities audiences demonstrated a particular interest. This was partly because of the costs involved in â€Å"manufacturing stardom† on a scale which the studies could translate into measureable box-office revenue, and for fear of the power which stars might then wield. Stars need all kinds of resources lavished on their construction such as privileged access to screen and narrative space, to lighting, to the care of costumers, make-up workers, voice coaches, personal trainers, etc. , as well as to audience interest through previews, supply of publicity materials, etc. Skillful casting is also important, though rarely discussed in work on stars, perhaps because it is seen to detract from the star’s own intentions in a performance. Key career decisions involve a star’s choice of casting agency or the choices made by a particular film’s casting director. Once established, the star system worked lucratively for the studios. Stars were used as part of the studio’s â€Å"branding† or promise of certain kinds of narrative and production values. They were useful in â€Å"differentiating† studios’ films. Stars were literally part of the studio’s capital, like plant and equipment, and could be traded as such. James Stewart, making an interesting comparison with sports celebrities, said once â€Å"Your studio could trade you around like ball player like when I was traded once to Universal for the use of their back lot for three weeks. † Stars’ large salaries, said to be due to nebulous qualities such as â€Å"talent† or â€Å"charisma†, worked to negate the powers of acting unions, who might otherwise have been able to calculate acting labor and ask for more equal distribution of profits (Branston and Stafford 2003). And stars have always functioned as a key part of Hollywood’s relationship to broader capitalist structures. In the 1930s, for example, over-production of manufactured goods had reached crisis point in North America, and the large banks funding Hollywood sought its help in shifting goods from warehouses to consumers. In addition to this, the celebrity is part of the public sphere, essentially an actor or, to use Robert Altman’s 1992 film characterization of Hollywood denizens, a â€Å"player. † In the contemporary public sphere, divisions exist between different types of players: politicians are made to seem distinctly different from entertainment figures; businesspeople are distinguished from sports stars. And yet in the mediated representation of this panoply of players, they begin to blend together. Film stars like Arnold Schwarzenegger share the stage with politicians like George Bush; Gorbachev appears in a film by Wenders; Michael Jackson hangs out on the White House lawn with Ronald Reagan; Nelson Mandela fills an entire issue of Vogue. The celebrity is a category that identifies these slippages in identification and differentiation. Leadership, a concept that is often used to provide a definitional distance from vulgarity of celebrity status, provides the last discursive location for understanding the public individual. The argument I want to advance here is that in contemporary culture, there is a convergence in the source of power between the political leader and other forms of celebrity. Both are forms of subjectivity that are sanctioned by the culture and enter the symbolic realm of providing meaning and significance for the culture. The categorical distinction of forms of power is dissolving in favor of a unified system of celebrity status, in which the sanctioning of power is based on similar emotive and irrational, yet culturally deeply embedded, sentiments (Marshall 1997). Of course, depending on the type of media where actors and actresses appear, their power and charisma varies. In addition to this, depending on the type of media used, individual’s star quality or qualities of being a celebrity varies. On television, an individual can become a star without ceasing to be his or her anonymous self, because the medium celebrates innocuous, domestic normality. Once on the â€Å"The Tonight Show† Jack Paar maddened the studio audience by attentively quizzing one of its number and ignoring Cary Grant, who’d been planted in the adjoining seats. As well as a practical joke, this was a boast of television’s license to bestow celebrity on those it promiscuously or fortuitously favors. But the medium can just as easily rescind that celebrity. Obsolescence is built into the television star, as it is into the sets themselves: hence those mournful commercials for American Express in which the celebrities of yesteryear- the man who lent his croaky voice to Bugs Bunny or a candidate for the Vice-Presidency in 1964- laud the company’s card, which restores to them an identity and a televisibility they’d forfeited. The game show contestants experience this brief tenure of television celebrity- Warhol’s fifteen minutes- at its most accelerated. But in order to quality for it, they have to surrender themselves to the medium. Their only way of winning games is to abase themselves, feigning hysteria on â€Å"The Price is Right,† exchanging sordid confidences on â€Å"The Newlywed Game,† incompetently acting out inane charades on Bruce Forsyth’s â€Å"Generation Game. † The cruelest of the games is â€Å"The Gong Show,† where one’s span of celebrity may not even extend to fifteen seconds. More or less, untalented contestants sing, dance, juggle or fiddle until the inevitable gong sends them back to nonentity. For some, the gong supervenes immediately. They’ve been warned this will happen, and coached to disappear with dignity, but are expected to go through with their act all the same and suffer their condemnation. Even a few seconds of television fame is worth the price of one’s self-esteem. The show pretends to be a talent quest, but is a smirking parody of that. The hosts on the game shows are, for similar reasons, parodies of geniality. A host soothes his guests and smoothes obstacles out of their way. But in homage to Groucho, the comperes subject their victims to a ritual humiliation, and their patter keeps the game-players throughout flinching and ill-at-ease (Conrad 1982). Television is good but may not be ideal for preserving important works. On the other hand, a good film can be shown anywhere in the world where there is an audience. Furthermore, the cinema will turn actors and actresses into stars. There are many well-known television actors and actresses, but they have no international fame like their big-screen counterparts. Films together with film magazines contribute directly to the formation of a star system and its attendant mythology. The stars perceived themselves to be, and were in turn also used as, icons for a modern lifestyle, especially fashion (Zhang 2005). They are given greater chances to achieve or receive international awards and become known not only in a particular state but to the whole world, unlike in the case of television stars. Those famous actors who appeared on television ten years ago have now vanished due either to lot or disintegrated videotape or a lack of interest by the contemporary audience. In Africa, there was a necessity to build more cinema theaters, instead of enforcing further use of television, because it was helping them to maintain a viable film industry. In Iran, they have more than 150 cinema houses. Their industry if progressing because they have a loyal audience who make it possible to recuperate money invested in production, which in turn is invested in the making of new films (Ukadike 2002). As a whole, it can be said that fame in cinema is more lasting than fame in television. In addition to this, the stars or celebrities appearing on cinemas rather than on televisions are the ones who are more favored by producers and stockholders. Moreover, they are preferred than the television stars to be used in magazines, especially if it is an international magazine. As such, the lifestyle of actors and actresses in cinemas are greater than those who only appear in television shows. The cinema industry as well as its actors and actresses are greatly favored and nowadays, more specifically preferred by a good number of the countries. Bibliography BRANSTON, GILL and STAFFORD, ROY, The Media Students Book (USA: Routledge, 2003). CONRAD, PETER, Television (USA: Routledge, 1983). MARSHALL, P. DAVID, Celebrity and Power: Fame in Contemporary Culture (Minneapolis: Regents of the University of Minnesota, 1997). UKADIKE, NWACHUKWU FRANK, Questioning African Cinema (Minneapolis: University of Minnesota Press, 2002). ZHANG, ZHEN, An Amorous History of the Silver Screen (London: University of Chicago Press, 2005).

Antilock Brake System Abs Model Based Design Computer Science Essay

Antilock Brake System Abs Model Based Design Computer Science Essay An Antilock Brake System (ABS) is a closed loop control system that modulates the brake torque that is applied to the wheel in order to prevent the controlled wheel from becoming fully locked. ABS is among the most important safety systems in a vehicle. In automatic highway system, automatic brake actuation is a very important part of the overall vehicle control system. It prevents the wheel lock-up under critical braking conditions, such as those encountered with wet or slippery road surfaces and driver panic reaction (Bosch, 1995). By preventing the wheel lock-up, ABS ensures that the vehicle remains responsive to steering wheel inputs. Reduced stopping distance on account of ABS is more evident on wet or slippery road surfaces (Garrick et al., 1998). 1.2 MODEL BASED DESIGN Designers of embedded control system software face difficult challenges. In addition to the need to complete projects at low cost and within tight schedules, embedded control system software designers must provide predictable performance and competitive features for the products they deliver. Traditional methods of designing, testing, and implementing embedded control systems cause designers to wait until late in the design effort, when actual or prototype products and real-time embedded targets become available, to find out if software really works as it was intended to. Only then, as system integration occurs, can the designer uncover the errors that may have found their way into the product during the early design stages. Model-Based Design with MathWorks tools provides a proven technique for creating embedded control systems. It is used today for satellites, aircraft, and many other aerospace applications, in the automotive industry, and for process control, computer peripherals and industrial machinery. Through Model-Based Design, embedded control system design teams can begin evaluating software designs without using prototype products and real-time targets. The MathWorks environment for Model-Based Design allows engineers to mathematically model the behavior of the physical system, design the software and model its behavior, and then simulate the entire system model to accurately predict and optimize performance. The system model becomes a specification from which you can automatically generate real-time software for testing, prototyping, and embedded implementation, thus avoiding manual effort and reducing the potential for errors. Fig 1.1. Model-Based Design for embedded control system software Changes or corrections to the system requirements and specifications are easily incorporated into the model, fully evaluated by simulation, and automatically reflected in the final real-time embedded software. 1.3. MODELING AND SIMULATION To effectively design an embedded control system and accurately predict its performance, designers must understand the behavior of the entire system in which the control system will reside. MATLAB and Simulink form the core environment for Model-Based Design for creating accurate, mathematical models of physical system behavior. The graphical, block-diagram paradigm of the MathWorks environment lets you drag-and-drop predefined modeling elements, connect them together, and create models of dynamic systems. These dynamic systems can be continuous-time, multi-rate discrete-time, or virtually any combination of the three. You can create custom model elements or reuse legacy code-based models by incorporating C, Fortran, or Ada code directly into the modeling environment. The modeling environment is hierarchical and self-documenting. System structure and function can be clearly expressed by grouping model elements in virtually any combination, allowing large teams to work concurrently on the design. Libraries of hierarchical elements can be quickly created, allowing those elements to be reused easily by other members of the design team or on subsequent designs. Fully integrated into the environment is the capability to graphically model event-driven systems using state charts, truth tables, and flow diagrams. Specialized capability for mechanical and electrical power systems allows models of these systems to be constructed using modeling elements that correspond directly to the structure of the physical system, avoiding the need to express them as mathematical equations. If prototype or actual physical systems are available and input/output data can be acquired from them, mathematical models can also be created using system identification techniques. As soon as a hierarchical element of the model is constructed, that element can be simulated. Simulation allows specification, requirements, and modeling errors to be found immediately, rather than waiting until later in the design effort. As the model becomes larger, through the addition of hierarchical elements or by increasing the complexity of existing ones, the designer can continue to find and correct errors during simulation by using the model coverage, performance profiling, and interactive debugging features. When the physical system model is specified to the required level of detail and simulation has shown the model to be accurate, the control system can be designed. 1.4. CONTROL SYSTEM SOFTWARE DESIGN With the behavioral model of the physical system available, the designer can begin the embedded control system software design. The MathWorks environment for Model-Based Design supports many types of control system design techniques and requirements that range from the simple to the most complex and large-scale. For example, some product designs may require using linear control design methods to determine the correct algorithms and parameters for the control system software. Using MATLAB and Simulink, the designer can automatically create the linear physical system models needed by this design technique, calculate the parameters, and then visualize the results using Bode plots and root locus diagrams. Other applications may require less sophisticated techniques to determine the correct control system design. Regardless of the control system design method used, the MathWorks environment for Model-Based Design helps the designer use interactive simulation to quickly evaluate each contr ol system design model in conjunction with the physical system model and avoid the risk, expense, or need for prototypes or actual physical systems. As the control system functional design is completed and the target environment needs to be considered, the designer can specify implementation details for the software directly in the modeling environment. The MathWorks environment supports all aspects of control system software design, including processor, interface, or standards issues. For example, you may need scaled integer or fixed-point data types for target processors that have no floating-point math capability. The effects of fixed-point mathematics can be evaluated by simulation, to see if the proper data sizes and scale factors have been selected. Data structures that are needed to meet software standards or target environment interface requirements can be defined as part of the system model and then realized when the embedded control system software is automatically generated. When the control system software design is complete, you can simulate the entire system model. During simulation, you can automatically collect model profiling and coverage information that will help you assess performance and discover errors. If performance does not meet expectations or errors are found, you can easily change the model to correct the problem and then simulate the model again to confirm the change or correction. Once simulation of the entire system model has shown that the design meets the desired performance requirements, you can automatically generate software for real-time testing and implementation, using the model as a specification. 1.5. EMBEDDED SOFTWARE TESTING AND IMPLEMENTATION Using the system model and Real-Time Workshop, real-time code for testing, validation, and embedded implementation on the production target processor can be automatically generated. As it is created, the code is automatically optimized for fast execution and efficient use of memory. Automatically generating code from the system model avoids errors due to manual translation of the model into code, and saves time, allowing software developers to focus on more demanding tasks. The MathWorks provides a turnkey software environment called xPC Target for real-time prototype testing, calibration, and validation of this automatically generated code using a PC-based hardware target system. xPC Target includes a real-time kernel, device drivers, and all the support software needed to create a rapid control prototyping system for real-time software testing and validation. It can also be used to provide hardware-in-the-loop capability, using code generated automatically from the physical system model. Hardware-in-the-loop testing allows the designer to simulate the real-time behavior and characteristics of their physical system, so that prototype or production control system software can be tested without the need for the actual hardware or operational environment. For embedded system designers who prefer an integrated capability, The MathWorks has a fully tested, custom configured, PC-based target hardware system. Chapter 2 MODELING AND SIMULATION 2.1. MODELING A computer model, as used in modeling and simulation science, is a mathematical representation of something-a person, a building, a vehicle, a tree-any object. A model also can be a representation of a process-a weather pattern, traffic flow, air flowing over a wing. Models are created from a mass of data, equations and computations that mimic the actions of things represented. Models usually include a graphical display that translates all this number crunching into an animation that you can see on a computer screen or by means of some other visual device.   Models can be simple images of things-the outer shell, so to speak-or they can be complex, carrying all the characteristics of the object or process they represent. A complex model will simulate the actions and reactions of the real thing. To make these models behave the way they would in real life, accurate, real-time simulations require fast computers with lots of number crunching power. 2.2. SIMULATION Simulations (and models, too) are abstractions of reality. Often they deliberately emphasize one part of reality at the expense of other parts. Where as models are mathematical, logical, or some other structured representation of reality, simulations are the specific application of models to arrive at some outcome. 2.2.1 Types of simulations Simulations generally come in three styles: live, virtual and constructive. A simulation also may be a combination of two or more styles. Live simulations typically involve humans and/or equipment and activity in a setting where they would operate for real. Think war games with soldiers out in the field or manning command posts. Time is continuous, as in the real world. Another example of live simulation is testing a car battery using an electrical tester. Virtual simulations typically involve humans and/or equipment in a computer-controlled setting. Time is in discrete steps, allowing users to concentrate on the important stuff, so to speak. A flight simulator falls into this category. Constructive simulations typically do not involve humans or equipment as participants. Rather than by time, they are driven more by the proper sequencing of events. A simulator is a device that may use any combination of sound, sight, motion and smell to make you feel that you are experiencing an actual situation. Some video games are good examples of low-end simulators. Simulations are complex, computer-driven re-creations of the real thing. When used for training, they must recreate reality accurately; otherwise you may not learn the right way to do a task. 2.3. MODELING AND SIMULATING ORDINARY SECOND ORDER DIFFERENTIAL EQUATION Consider the second order differential equation (1) This can be written as two first order differential equations if we introduce two new variables, x1(t) and x2(t).   Let x1(t)=y(t).   We can then write two coupled first order equations. (2) (3) The solution can be approximated in Simulink by using two integrators to integrate the first order derivatives. 2.3.1. Building a Simulink Model We start Simulink from the Matlab prompt by typing Simulink.    We will be needing blocks from the Source, Sink, Linear and Non-linear libraries, so double click on them to open them up.   In the window labeled untitled, drag two integrators from the Linear library, connect them, and change their labels. Fig2.1. Building Simulink Model (Step 1) The input to the leftmost integrator is the derivative of x2, and its output is x2.   The input to the rightmost integrator is the derivative of x1 (=x2), and its output is x1.   We can complete the representation of the differential equation except for the input, by adding two gain blocks (and flipping them using the Format option of the Simulink menu. Fig2.2 Building Simulink Model (Step 2) To add the input we will use the clock (from Source), the trigonometric function (from Non-Linear) and another gain block.   The completed diagram should look like the one shown below. Fig2.3. Building Simulink Model (Step 3) 2.3.2. Running Simulation and Viewing Results To view the results of the simulation, add a scope (from Sink).   In this case we only want to view 80 ms of simulation, so go to the Simulation menu and choose Parameters, and set the stop time to 0.08 seconds.   To start the simulation hit the start button, or go to Simulation->Start.   The scope output is shown below (after zooming with the Binocular tool at the top of the scope window. Fig2.4 Simulation Results of the Model It is often desirable to save the data to Matlab.   To save the time variable, the input and the output, we add three To Workspace blocks (from Sink) and give them each a different name (these are the names of the variables that will be in the Matlab workspace). Fig2.5 Building Simulink Model (Step 4) Chapter 3 ANTI-LOCK BRAKING SYSTEM 3.1 INTRODUCTION Antilock Braking Systems (ABS) are closed loop control devices within the braking systems which prevent the wheel lock-up during braking and as a result, retain vehicle steerability and stability. The main ABS components are hydraulic modulators, wheel speed sensors, ECU for signal processing and control and triggering of the signal lamp and of the actuators in the hydraulic modulator. Fig 3.1 Location of the ABS in a vehicle 3.2 DESCRIPTION OF THE SYSTEM The theory behind anti-lock brakes is simple. A skidding wheel (where the tire contact patch is sliding relative to the road) has less traction than a non-skidding wheel. If we have been stuck on ice, for example, we know that if the wheels are spinning we have no traction. This is because the contact patch is sliding relative to the ice. By keeping the wheels from skidding while we slow down, anti-lock brakes benefit in two ways: The vehicle stops faster, and we will be able to steer while we stop. There are four main components to an ABS system: Speed Sensors, Pump, Valve and an ECU. 3.2.1 Speed Sensor The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information. 3.2.2 Valves There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions: In position one, the valve is open; pressure from the master cylinder is passed right through to the brake. In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder. In position three, the valve releases some of the pressure from the brake. 3.2.3 Pump Since the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up. 3.2.4 The ECU The ECU receives, filters and amplifies the speed sensor signals and ascertains from them the degree of wheel slip and the acceleration of the individual wheels as well as the reference speed which is the best possible calculation of the vehicle road speed. Most of the systems use vehicle specific LSI circuits for this purpose. Fig 3.2 Anti Lock Brake Pump and Valves 3.3 WORKING OF ABS There are many different variations and control algorithms for ABS systems. We will discuss how one of the simpler systems works. The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before the wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 kph) under ideal conditions, but a wheel that locks up could stop spinning in less than a second. The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power. When the ABS system is in operation we will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. Some ABS systems can cycle up to 15 times per second. 3.4 TYPES OF ABS: Anti-lock braking systems use different schemes depending on the type of brakes in use. Referring them by the number of channels, that is, how many valves that are individually controlled and the number of speed sensors, we have the following:   i) Four-channel, four-sensor ABS This is the best scheme. There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force. ii) Three-channel, three-sensor ABS This scheme, commonly found on pickup trucks with four-wheel ABS, has a speed sensor and a valve for each of the front wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle. This system provides individual control of the front wheels, so they can both achieve maximum braking force. The rear wheels, however, are monitored together; they both have to start to lock up before the ABS will activate on the rear. With this system, it is possible that one of the rear wheels will lock during a stop, reducing brake effectiveness. iii) One-channel, one-sensor ABS This system is commonly found on pickup trucks with rear-wheel ABS. It has one valve, which controls both rear wheels, and one speed sensor, located in the rear axle. This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in. In this system it is also possible that one of the rear wheels will lock, reducing brake effectiveness. This system is easy to identify. Usually there will be one brake line going through a T-fitting to both rear wheels. We can locate the speed sensor by looking for an electrical connection near the differential on the rear-axle housing. Chapter 4 IMPLEMENTATION OF ANTI-LOCK BRAKING SYSTEM 4.1 BLOCK DIAGRAM OF ABS On initial braking, the brake pressure is increased, the brake slip ÃŽÂ » rises and at the maximum point on the adhesion/slip curve, it reaches the limit between the stable and unstable ranges. From this point on, any further increase in the brake pressure or braking torque does not cause any further increase in braking force FB. In the stable range, the brake slip is largely deformation slip, it increasingly tends towards skidding in the unstable range. Actuator Desired Slip Controller Vehicle Dynamics Actual Slip Fig4.1. Block Diagram of ABS We model the ABS using Matlab/Simulink where in the various mechanical blocks are realized and mathematical models of the same are readily available in the Simulink library. The ABS simulation model follows the below shown control loop. The reference variable is the desired relative slip which is fed as an input to the system. The control system in our case is the wheel whose parameters like wheel speed are measured. The feedback path consists of the user defined equation which measures the relative slip of the wheel and the error is rectified at the initial stage. The model represents a single wheel, which may be replicated a number of times to create a model for a multi-wheel vehicle. Fig 4.2. ABS Control Loop 4.2 ANALYSIS OF ABS: For understanding the concept of ABS, we make use of the free body diagram of a wheel. We make use of the formulae for force and torque acting on the wheel. The below figure gives us a clear understanding about the forces acting on a wheel. The wheel rotates with an initial angular speed that corresponds to the vehicle speed before the brakes are applied. We used separate integrators to compute wheel angular speed and vehicle speed. We use two speeds to calculate slip, which is determined below. Note that we introduce vehicle speed expressed as an angular velocity (see below). . (Equal to wheel angular speed if there is no slip.) (1) Fig 4.3 Free Body Diagram of a single wheel (2) (3) is the wheel speed divided by the wheel radius. is the vehicle linear velocity. is the wheel radius. is the wheel angular velocity. We can also write (3) as (4) Where V is the vehicle speed, à Ã¢â‚¬ ° is the wheel speed and r is the radius of the wheel. From these expressions, we see that slip is zero when wheel speed and vehicle speed are equal, and slip equals one when the wheel is locked. A desirable slip value is 0.2, which means that the number of wheel revolutions equals 0.8 times the number of revolutions under non-braking conditions with the same vehicle velocity. This maximizes the adhesion between the tire and road and minimizes the stopping distance with the available friction. If an excessive brake torque is applied, the wheel will be locked, which means that it slides on the road surface but does not rotate at all. A locked wheel has no lateral stability and less longitudinal friction force, which is the ultimate force to stop the vehicle. Thus, a braking with a locked wheel will cause longer stopping distance and lateral instability. The tire force from the road surface causes the wheel velocity to increase, thus decreases the wheel slip. A high ÃŽÂ ¼ leads to a large tyre force and a low ÃŽÂ ¼ leads to a small tyre force. In the increasing part of the ÃŽÂ ¼-slip curve, an increase of the wheel slip leads to a larger ÃŽÂ ¼ and a larger tyre force, which reverses the wheel slip to a small value. However, in the decreasing part of the ÃŽÂ ¼-slip curve, an increase of the wheel slip leads to a smaller ÃŽÂ ¼ and a smaller tyre force, which causes the wheel slip to increase continuously. So, the peak point of the ÃŽÂ ¼-slip curve is criti cal. When a braking is initiated, the wheel velocity starts to decrease and the wheel slip starts to increase from zero. The wheel slip may stop increasing and start to decrease before the ÃŽÂ ¼ reaches its peak point. But if an excessive brake torque is applied, the wheel slip may go straightly to a large number, which causes the ÃŽÂ ¼ to pass its peak point and reach somewhere in the decreasing part of the ÃŽÂ ¼-slip curve. If the brake torque is not reduced quickly at this point, the reduction of the road friction force will lead to a rapid increase of the wheel slip and eventually to a wheel lockup. ABS tries to detect when this peak point is going to be reached and then reduces the brake torque properly so that a wheel lockup could be avoided. Fig 4.4. ÃŽÂ ¼-slip Friction Curve It appears to be true that maintaining the wheel slip at the peak point of the ÃŽÂ ¼- slip curve is ideal. However, the position of the peak ÃŽÂ ¼ point varies on the different road surfaces. In addition, stay at the peak point of the ÃŽÂ ¼- slip curve sometime may lead to a poor lateral stability. Thus, many control strategies define their performance goal as maintaining the wheel slip near a value of 0.2. This represents a compromise between the lateral stability, which is best at ÃŽÂ »=0 and the maximum deceleration which usually appears when ÃŽÂ » is between 0.1 and 0.3. 4.3 IMPLEMENTATION The friction coefficient between the tire and the road surface,  µ, is an empirical function of slip, known as the  µ-slip curve. We created mu-slip curves by passing MATLAB variables into the block diagram using a Simulink lookup table. The model multiplies the friction coefficient,  µ, by the weight on the wheel, W, to yield the frictional force, Ff, acting on the circumference of the tire. Ff is divided by the vehicle mass to produce the vehicle deceleration, which the model integrates to obtain vehicle velocity. In this model, we used an ideal anti-lock braking controller, that uses bang-bang control based upon the error between actual slip and desired slip. We set the desired slip to the value of slip at which the  µ-slip curve reaches a peak value, this being the optimum value for minimum braking distance (see note below.). Note: In an actual vehicle, the slip cannot be measured directly, so this control algorithm is not practical. It is used here to illustrate the conceptual construction of a simulation model. Fig 4.5. Simulink Model of the ABS In the above figure, the wheel speed, vehicle speed and the stopping distance are measured and the error value is fed back through the feedback path. Also, tire torque and the relative slip are fed as inputs to the wheel speed block. Notice that the model is a reference model which has its own internal block. Double click on the Wheel Speed subsystem in the model window to open it. Given the wheel slip, the desired wheel slip, and the tire torque, this subsystem calculates the wheel angular speed. To control the rate of change of brake pressure, the model subtracts actual slip from the desired slip and feeds this signal into a bang-bang control (+1 or -1, depending on the sign of the error). This on/off rate passes through a first-order lag that represents the delay associated with the hydraulic lines of the brake system. The model then integrates the filtered rate to yield the actual brake pressure. The resulting signal, multiplied by the piston area and radius with respect to the wheel (Kf), is the brake torque applied to the wheel. Fig 4.6. Wheel Speed Model for the ABS The model multiplies the frictional force on the wheel by the wheel radius (Rr) to give the accelerating torque of the road surface on the wheel. The brake torque is subtracted to give the net torque on the wheel. Dividing the net torque by the wheel rotational inertia, I, yields the wheel acceleration, which is then integrated to provide wheel velocity. In order to keep the wheel speed and vehicle speed positive, limited integrators are used in this model. After we build the ABS model in simulink, we have to configure the parameters related to simulation of the model. We need to specify that the signals are exported to the Matlab workspace where they are analyzed and results are viewed. This is done by checking the signal logging field in the configuration parameters option provided in the simulation tab. Fig 4.7. Configuring Parameters for the model We make a Matlab code which makes use of the inputs and outputs used by the simulink model and we plot the waveforms. 4.3.1 ABS Code h = findobj(0, Name, ABS Speeds); if isempty(h), h=figure(Position,[26 239 452 257], Name,ABS Speeds, NumberTitle,off); end figure(h) set(h,DefaultAxesFontSize,8) logsout.unpack(all); plot(Vs.Time, Vs.Data); set(findobj(type,line),color,[0 1 0]); hold on; plot(Ww.Time, Ww.Data); title(Vehicle speed and wheel speed); ylabel(Speed(rad/sec)); xlabel(Time(secs)); set(gca,Position,[0.1300 0.1500 0.7750 0.750]); set(get(gca,xlabel),FontSize,10); set(get(gca,ylabel),FontSize,10); set(get(gca,title),FontSize,10); % Plot arrow with annotation hold on plot([5.958; 4.192],[36.92; 17.29],r-,[5.758; 5.958; 6.029],[36.55; 36.92; 35.86],r- ) text(8.533,54.66,Vehicle speed (omega_v),FontSize,10) plot([7.14; 8.35],[43.1; 56.3],r-,[7.34; 7.14; 7.07],[43.4; 43.1; 44.1],r- ) text(4.342,15.69,Wheel speed (omega_w),FontSize,10) drawnow hold off h = findobj(0, Name, ABS Slip); if isempty(h), h=figure(Position,[486 239 452 257], Name,ABS Slip, NumberTitle,off); end figure(h); set(h,DefaultAxesFontSize,8) slp = logsout.slp.Data; time = logsout.slp.Time; plot(time,slp); title(Slip) xlabel(Time(secs)) ylabel(Normalized Relative Slip) set(gca,Position,[0.1300 0.1500 0.7750 0.750]) set(get(gca,xlabel),FontSize,10) set(get(gca,ylabel),FontSize,10) set(get(gca,title),FontSize,10) Chapter 5 RESULTS AND CONCLUSION After building the model, we simulate it using the options provided in the same Simulink window. 5.1 RUNNING THE SIMULATION 5.1.1 With ABS Press the Play button on the model toolbar to run the simulation. We can also run the simulation by executing the sim(FILE NAME) command in MATLAB. ABS is turned on during this simulation. Fig 5.1 Vehicle Speed and Wheel Speed(with ABS) The model logs relevant data to MATLAB workspace. Logged signals have a blue indicator. In this case yout and slp are logged (see the model).The above figure visualizes the ABS simulation results. The first plot in figure shows the wheel angular velocity and corresponding vehicle angular velocity. This plot shows that the wheel speed stays below vehicle speed without locking up, with vehicle speed going to zero in less than 15 seconds. Fig 5.2 Normalised Relative Slip(with ABS) 5.1.2 Without ABS For more meaningful results, consider the vehicle behavior without ABS. At the MATLAB command line, set the model variable ctrl = 0. This disconnects the slip feedback from the contro

Socrates: The Greek Philosopher :: essays research papers

The life of the Greek philosopher Socrates (469-399 BC) marks such a critical point in Western thought that standard histories divide Greek philosophy into pre-Socratic and post-Socratic periods. Socrates left no writings of his own, and his work has inspired almost as many different interpretations as there have been interpreters. He remains one of the most important and one of the most enigmatic figures in Western philosophy. As a young man Socrates became fascinated with the new scientific ideas that Anaxagoras and the latter's associate Archelaus had introduced to Athens. He seems for a time to have been the leader of an Athenian research circle--which would explain why the first appearance of Socrates in literature is as a villainous, atheistic scientist in The Clouds of Aristophanes. Young Socrates also knew the Sophists and listened to their debates and ceremonial orations. Socrates and the Sophists Neither science nor Sophistry, however, could answer a new philosophic questio n that struck him. The earlier Greek thinkers had been concerned almost wholly with physics and cosmology until the Sophists suggested that what should be done instead was to teach young men skills to satisfy their natural self-interest. Instead, Socrates wondered: "What is a 'self'?" Although "Know Thyself!" was one of three sayings carved on the Temple of Apollo at Delphi, the directive proved difficult to carry out. The so-called scientific views of the time, particularly that of atomism, defined the self as a physical organ that responded to environmental pressure. Socrates felt, however, that the Sophists, for all their talk of self-interest, had little curiosity about the status of a self; they assumed that it was merely an isolated center constantly greedy for more pleasure, prestige, and power. The Sophists further thought that the values that people advocated were all conventional, varying from one culture to another, and that no one would ever act again st his or her own interest, regardless of how many people talked as though they would. This complex of ideas offered little to explain human nature and excellence. Socrates' Later Life and Thought Socrates, setting about his search for the self, was convinced of the importance of his quest. Until educators and teachers knew what human excellence was, he thought, they were engaging in false pretenses by claiming that they knew how to improve students or societies. Socrates believed that objective patterns, or "forms," exist that define human excellence, that these are neither culturally relative nor subjective, and that philosophic inquiry could discover them.

How successful is Dickens in his presentation of female characters? :: Free Essay Writer

How successful is Dickens in his presentation of female characters? There are many female characters in Great Expectations, but most of them are quite incidental and of no great significance to the plot. Some of them however are essential to the story and play a large part in the plot. Miss Havisham, combined with Estella are the people who are the ‘snobby’ influence in Pips life, they seem to become desirable characters to Pip after he meets them for the first time at Satis house. Their values do battle with his own at the end of chapter 9; the values that Miss Havisham and Estella have introduced to him, and Joe's humanistic values that he has grown up with. Questions have been raised over whether Miss Havisham and Estellas are believable as actual characters. Miss Havisham can be described as over-dramatised as a decaying part of a decaying house where time has been suspended. She is calculated and spiteful almost to unrealistic odds. There is also a hint of witchery in her character, evident in chapter 29 where she tells Pip to love Estella; â€Å" ‘If she tears your heart to pieces - and as it gets older and stronger, it will tear deeper - love her, love her, love her!’................it could not have sounded from her lips more like a curse.† This passage, where Miss Havisham is charged with almost a sexual ene rgy, is quite frightening to the young Pip. She has created Estellas to wreak her own revenge on men, and is successful in this, but in the process becomes devoted to Estella herself, and then feels pain when Estella cannot return her feelings as she has been rendered ‘heartless’ by Miss Havisham's upbringing. The fact that she shows remorse at the end of the book gives her character an added depth, and therefore most people feel she becomes more realistic. She is a victim of her own creation, and a figure of pity. We first meet Estellas as a quite nasty child, very aware of how her class makes her ‘better’ than most people. She enjoys Pips pain and humiliation when he visits Satis house, and enjoys putting him down due to his â€Å"labourers hands† and â€Å"coarse boots†. In the true style of a young lady of her class of the time she is sent abroad to a ‘finishing’ school, and returns to her dà ©butante in London, once again meeting Pip.

House on Mango Street Essay -- Book Review Poverty Education Essays

House on Mango Street The story; themes; and implications for teaching from the House on Mango Street come from showing how today’s society has low expectations for those in the inner city. This book can be used to show what inner life is like and how these people are looked at and treated by others in society. Using this book in the classroom can be beneficial because many people have negative preconceptions of what life is really like as a minority. I know that I think of inner city schools and the students that attend them as underprivileged and don’t hold them to the same standards as I do others from smaller more suburban towns. Going to Milwaukee this semester has been a culture shock and I think that reading this book compliments are experiences doing our observation and participation. This story is about a young Spanish girl, Esperanza, who is growing up in the Latino section of Chicago. She is embarrassed of where she lives because of the poor conditions of her house, the mice that run freely around her, and the neighborhood she comes from. Her neighborhood is inner city living where the cops are looked at as the bad people in the neighborhood, homeless people sleep in the streets, and she has seen many other bad things including rape and abuse. Esperanza struggles to fit into her new home because she has moved so often. She can’t find and keep friends. Esperanza doesn’t want to fit though because all she can think about is getting out of there and having the white picket fence in the suburbs someday. She does not consider her house on Mango Street her home. It is more of a temporary dwelling until she can get out of there. She works hard at a young age to help her family with the money problems. The story is also about finding some good friends in her new home and her adventures with them. The most interesting themes, issues and characters are Esperanza and her dreams of getting out of the house on Mango Street. This book keeps you captured by telling stories of how she wants to get out of the city and off Mango Street. They are all very interesting and this is what makes the book so fun to read. Making friends and keeping them is also an important issue in this young girls life because she moves so often. I think these things are interesting because I can relate to wanting to get out of where I was when I ... ...go Street. It is eye opening and after taking this class and others like it, I look at these books in a different light. This book seemed like an accurate portrayal of what life must have been like for this girl and I could tell I was emotionally into it. I could feel her pain even though I have not gone through these things first hand as she has. It was a sad story but I think it got the point across without saying â€Å"feel sorry for me because I live in the inner city.† This book can be used with students to show that people from diverse populations are just like you and me. They just want to live a healthy and fulfilling life with friends and family. Most of them are trying to make a better life for themselves any way possible. This will help my students see others as equals and not as people of lesser value. I think it can also be used with inner city children to show that nobody is going to feel sorry for them and if they want a better life than they have to earn it themselves. Nobody is going to give them free hand outs all their lives and if they want something bad enough then they have to work for it. This book can be a powerful tool in teaching that to students.

Classroom Management And Discipline In Regular Classrooms

In â€Å" Learning to Teach, Teaching to Learn, † Harry and Rosemary Wong describe the successes and the jobs encountered by Jessica Fenton, who portions how she overcame some major obstructions she faced in her first twelvemonth of instruction. Fenton ‘s first challenge was that she was trained as an simple school instructor, but upon graduation, she was offered ( and accepted ) a place learning 9th grade English. Fenton felt overwhelmed and unprepared from the beginning, confronting jobs that were ne'er addressed in her college instruction classs. She was beguiling her clip instruction, coaching, chaperoning school dances, volunteering on assorted commissions, and assisting with graduation. Fenton was working from seven A.M. to midnight and still felt unprepared. By Christmas interruption of her first twelvemonth of instruction, Fenton was close to giving up on her dreams of being a instructor. Alternatively, she decided it was clip for a alteration and committed herself to larning how to go a better instructor. She attended seminars, attended workshops, read books, and stole any good thought she discovered along the manner. Fenton shortly realized that, with a few alterations, she could turn it all about. She started by developing a list of processs that would do her schoolroom modus operandis run swimmingly. Using the three measure theoretical account taught in The First Days of School by Harry Wong, Fenton taught these processs to her pupils by explicating each process, patterning and practising them with the category, and implementing a method of follow through to reenforce each process. Once Fenton created a new degree of direction and organisation to her schoolroom, she was able to learn with easiness. She besides distributed two press releases to her pupils. The first was a department-wide class lineation that explained the literature they would be analyzing, how they would be graded, and the policies for assignments and prep. Most significantly, at the underside of the paper was this statement: â€Å" The grade of success earned by the pupil will depend on committedness and ownership. If the three participants: pupil, parent/guardian, and teacher, work together, the pupil will see success. † This press release was sent place to parents and defenders to see. The 2nd press release was a Course Information page that laid out her major processs, listed the specific dislocation of how each twenty-four hours was traveling to be run, explained their forenoon bellwork, what to convey to category every twenty-four hours, and how they were to form their work. When F enton returned to school from the vacation interruption, she was a changed instructor. Because Fenton set clear outlooks of her pupils and herself, she set the phase for a successful remainder of the twelvemonth. At the beginning of the school twelvemonth in 2009, Fenton got the chance to run into her long-time graven image, Erin Gruwell, the instructor of the Freedom Writers. As a new instructor in Long Beach, CA, Gruwell was shocked to larn that merely one pupil in her category knew of the Holocaust. At that minute, she decided that her course of study would focus on on tolerance. Gruwell inspired 150 deprived pupils write their narratives, do films about their lives, keep diaries, read books about other adolescents, and associate the stuffs they studied to their ain lives. These pupils became known as the Freedom Writers. Gruwell founded the Freedom Writer Foundation in 1997. The end of the foundation is to â€Å" animate immature pupils to pick up pens alternatively of guns. † Now Gruwell portions her experiences with instructors across the state. After run intoing Fenton, Gruwell offered her an chance to come to the Freedom Writer Institute in California. Fenton gracefully attende d the Institution, and took what she learned back to her schoolroom. Fenton and Gruwell portion a deep passion for pupils and their profession. One of Fenton ‘s ends is to associate to each of her pupils in a personal manner. Now, on the first twenty-four hours of school, Fenton begins with a Power Point presentation presenting herself, her personal grounds for why she loves to learn, and fun facts about herself. Subsequently, her pupils make full out an in-class checklist to place the manner they learn best, what their concerns are, and what countries of the stuff they are fighting with. This encourages unfastened communicating between Fenton and her pupils. Inspired by Gruwell, Fenton sets high outlooks for her pupils by holding them make full out a study that asks what grade they hope to accomplish and how they plan to make so. The pupils are required to subscribe a statement that states their personal committedness to accomplishing their ends. Fenton is now in her 4th twelvemonth of instruction, and she believes that she has the best occupation in the universe. As an active subscriber to the New Brunswick Teachers ‘ Association and a member of the Ad Hoc Planning Committee, she portions her passion and dedication to doing a difference in her pupils ‘ lives. Though Fenton is a successful instructor, her end is to go on to larn from her pupils and to go a better pedagogue. Analysis The text edition states that Jacob Kounin conducted schoolroom surveies in the 1960 ‘s to nail the best manner to near schoolroom direction and subject. He found that good instructors used identifiable processs for deriving pupil attending and clear uping outlooks. These thoughts, which coincide with the Managerial attack, were used by Jessica Fenton to go a more effectual instructor. By puting up clear regulations, processs, and outlooks, Fenton was able to pull off and form her schoolroom in the 2nd half of her first twelvemonth. This is the recommended attack for new instructors, and one time in topographic point in, Fenton ‘s schoolroom modus operandis flowed swimmingly. By puting up clear modus operandis and processs, her pupils were organized and ready to larn. This besides left less chance for misbehaviour, because Fenton was maximising their acquisition clip. The text edition besides discusses the work of William Glasser, a head-shrinker and a great educational mind. He believes there are seven linking wonts that instructors can utilize to better dealingss between themselves and their pupils: lovingness, listening, back uping, lending, promoting, swearing, and befriending. These wonts, portion of the Humanistic attack, are used by Fenton to better her relationship with her pupils. On the first twenty-four hours of school Fenton portions facts about herself that allow the pupils to acquire to cognize her better. She besides uses an in-class checklist, in which the pupils tell her about themselves and their concerns. This opens up the lines of communicating between pupil and instructor, and promotes a figure of the linking wonts mentioned by Glasser. Fenton besides promotes ripening by holding the pupils fill out a study inquiring the class they hope to accomplish, and how they plan to make so. The pupils sign a personal committedness to ac complishing this end. In drumhead, the acquisition in Jessica Fenton ‘s schoolroom did non happen merely for her pupils. Because she was passionate about her pupils and her profession, she worked to better fix herself as an pedagogue. Her penetration was non new, as evidenced in the work of Kounin and Glasser, but her cognition of the attack to learning was new to her. Her committedness to personal growing and larning sets a criterion for her pupils to follow. A Wong, Harry and Rosemary. â€Å" Learning to Teach, Teaching to Learn. † Teachers.Net. Mar. 2010. Web. 04 June 2010. & lt ; hypertext transfer protocol: //teachers.net/wong/MAR10/ & gt ; .