Contradicting Theories On Choking Under Pressure Psychology Essay

Contradicting Theories On Choking Under Pressure Psychology Essay For several decades, the relationship between stress and performance gained much attention. Numerous psychological researches provided evidence for the anecdotal phenomenon that pressure negatively affects cognitive and motor control during performance. This phenomenon is known as choking under pressure, defined as performing more poorly than expected, in situations where performance pressure is at a maximum, given at ones skill level. Contradicting theories on choking under pressure A widely accepted explanation for choking under pressure in cognitive tasks is the distraction hypothesis (Wine, 1971). In accordance to distraction theories, it is proposed in high-pressure situations, the individuals attention needed to perform the task at hand is coopted by task irrelevant thoughts and worries such as worries about the situation and its consequences that leads to choking which harm their performances. (Beilock Carr, 2001; Lewis Linder, 1997; Wine, 1971). Essentially, pressure creates a dual-task environment in which situation-related concerns compete with the attention required to accomplish the task at hand. Distraction-based accounts of skill failure propose that performance pressure affects concentration from the main task that one is trying to perform to irrelevant cues. Therefore, there are insufficient working memory resources to successfully support both primary task performance and to deal with worries about the pressure situation and its consequences un der pressure which results in skill failure. Although there is evidence that pressure prompts failure by sidetracking attention away from skill performance, a contradicting class of theories has been put forth as an alternate explanation for skill failure. Baumeister (1984) proposed a self-focus theory called explicit-monitoring theory which claims the opposite that pressure could in ¬Ã¢â‚¬Å¡uence the performance of skilled individuals by causing them to engage explicit processes that interfere with carrying out the procedure such as increase in their self- consciousness and anxiety about performing well (Gray, 2004; Masters, 1992) which in turn leads performers to emphasize their attention on skill execution to ensure optimal result (Beilock Carr, 2001). This focus on the oneself is thought to prompt individuals to turn their focus inward on the precise processes of performance in an effort to apply more explicit monitoring and control than would be applied in a non-pressure situation. Rationale Distraction and explicit monitoring theories of choking under pressure pose very different mechanisms of skill failure. While distraction theories suggest that pressure influence performance by shifting attention and working memory resources away from it, explicit monitoring theories suggest that pressure shifts too much attention toward skill processes and procedures. However it is unclear as to whether distraction or explicit monitoring will impact performance, even though both mechanisms have tendencies to occur in certain contexts. We believe that pressure can do both in aspects of the performance environment itself. Distracting thoughts, explicit monitoring, or even both will be lead to depending on the specific elements of stress suffered in high-pressure situations as it may essentially involve multiple components; therefore, exerting multiple effects. The questions as to whether performance fail or succeed, and how this failure will occur, rest on aspects of the pressure situation and the required attention for the task being performed. Aim The aim of the experiment is to study the effect of different levels of pressure inflicted by an audience on peoples performance (word count and accuracy) in a typing task. Experimental outline This study was conducted on a total of 102 undergraduate psychology students, of which 54 were females and 48 were males. The participants ranged from 17 to 55 years of age (Mean=20.51 years; SD=6.28). The participants performed a typing task under 3 di ¬Ã¢â€š ¬erent environments which is no pressure, low pressure and high pressure in random order. The no pressure condition involves participants typing while the projector screen was turned off, so no one else in the room could see what they were typing. In the low pressure condition, the screen was turned on, so the rest of the class could see what was being typed. In the high pressure condition, the class crowded around the participant as they typed. In each condition, they are allocated a script of text which they need to replicate as much and as accurately as possible in the time allocated (45 seconds). Quality of performance is analyzed by counting the number of words typed and errors made. Hypothesis We hypothesize that pressure have a negative impact on performance. In no pressure condition, we predict that the participants would achieve the highest word count with lowest number of errors, whereas in high pressure condition, we predict that the participants would achieve the lowest word count with highest number of errors. Discussion The results showed that the number of words typed was significantly affected by pressured condition. Participants performance speed was fastest in the low pressure condition compared to the high-pressure condition. The results showed that accuracy was significantly affected by pressure condition. As for the participants accuracy, it was greater in the no-pressure condition compared to the low-pressure and the high-pressure condition. As such, the results of this study support the hypothesis proposed. These findings are consistent with the study conducted by Gray (2004) who examined how expert baseball players batted in a baseball simulator in both low-pressure and high-pressure conditions. Gray (2004) found an increase in batting errors and movement variability under high pressure, relative to low-pressure situation; suggesting that pressure negatively affects performance. As with the baseball players, we believe that our participants also experienced distracting thoughts and/or explicit monitoring under pressure which interrupted their performance. As a result, the participants experience a decrease in typing speed; hence, produced less word count and made more errors while typing. Strengths of the experiment This experiment assessed both male and female which rules out any possible gender difference. With the wide age range of 17 to 55 years of age, it also rules out age difference. Also, by manipulating the pressure environment, individuals will focus on the process of performance versus the outcome of performance, allowing us to study different aspects affecting ones performance in pressure-filled situations. Improvement to the experiment A larger sample size would have enabled us to achieve more accurate results. Significance This study enables us to better understand performance failure, and ways to prevent it; across a variety of skill types and situations, from a student taking a final exam paper to a professional athlete playing on the field. Such developed knowledge aids the improvement of training regiments and performance strategies designed to lighten these choking performances as such reducing the possibility of failure. Understanding the reason choking occurs is important for developing training methods to deal with it. Understanding skill failure and success under pressure may give a clear view on the similarities and differences in the cognitive control structures underlying a diverse set of skills. Furthermore, by uncovering the mechanisms thats leading pressure-induced failure, we can also further our understanding of how emotional and motivational factors combine with memory and attention processes to impact skill learning and performance. An understanding of how the performance environment modifies cognitive processes not only advances our understanding of the choking under pressure phenomenon explicitly but also provides an perception into related situations in which performance unintentionally falters, ranging from test anxiety to the threat of conforming to a negative stereotype. Finally, these  ¬Ã‚ ndings suggest an important avenue for future research working toward an all-embracing th eory of when performance will fail versus succeed under stressful situations.

Race Car Aerodynamics

Race Car Aerodynamics Gregor Seljak April 8, 2008 1 Introduction First racing cars were primarily designed to achieve high top speeds and the main goal was to minimize the air drag. But at high speeds, cars developed lift forces, which a? ected their stability. In order to improve their stability and handling, engineers mounted inverted wings pro? les1 generating negative lift. First such cars were Opel’s rocket powered RAK1 and RAK2 in 1928. However, in Formula, wings were not used for another 30 years. Racing in this era 1930’s to 1960’s occured on tracks where the maximum speed could be attained over signi? ant distance, so development aimed on reducing drag and potencial of downforce had not been discovered until the late 1960’s. But since then, Formula 1 has led the way in innovative methods of generating downforce within ever more restrictive regulations. Figure 1: Opel’s rocket powered RAK2, with large side wings 2 Airfoils Airfoil can be de? nead as a shape of wing, as seen in cross-section. In order to describe an airfoil, we must de? ne the following terms(Figure 2) †¢ The mean camber line is a line drawn midway between the upper and lower surfaces. †¢ The leading and trailing edge are the most forward an rearward of the mean camber line. Compared to an aircraft 1 †¢ The chord line is a line connecing leading an trailing edge. †¢ The chord length is the distance from the leading to the trailing edge, measured along the chord line. †¢ The camber is the maximum distance between mean camber line and chord line. †¢ The thickness is the distance between the upper and lower surfaces. Figure 2: Airfoil nomenclature The amount of lift L produced by the airfoil, can be expressed in term of lift coe? cient CL 1 2 (1) L = V? SCL 2 where V? denotes the freestrem velocity, ?uid density and S the airfoil area. 2. 1 Flow over an airfoilProperties of an airfoil can be measured in a wind tunnel, where constantchord wing spannes the entire test section, from one sidewall to the other. In this conditions, the ? ow sees a wing without wing tips. Such wing is called in? nite wing and streches to in? nity along the span. Because the airfoil section is identical along the wing, the properties of the airfoil and the in? nite wing are identical. Therefore the ? ow over an airfoil can be described as a 2D incompressible inviscid ? ow over an in? nite wing. Lift per unit span L? generated by an arbitrary airfoil(or any other body) moving at speed V? through the ? ud with density and circulation ? is 2 given by Kutta-Joukowsky theorem L? = V? ? . (2) Circulation around an airfoil, can be calculated with the concept of a vortex sheet, which was ? rst introduced by Prandtl an his colleagues. Consider an airfoil of arbitrary shape and thickness as shown in Figure 3. Circulation can be distributed over the whole airfoil area with surface density(vortex sheet strength) d? /ds = ? (s), where ? (s) must satisfy Kutta condition ? (trailing edge) = 0 (3) Entire circulation is then given by ?= ? (s)ds , (4) where the integral is taken around the complete surface of the airfoil.However, there is no general solution for ? (s) for an airfoil of arbitrary shape and it must be found numericaly, but analytical solutions can be found with some aproximations. Figure 3: Simulation of an arbitrary airfoil by distributing a vortex sheet over the airfoil surface. 2. 2 Thin airfoil theory Here we discuss thin airfoil in freestream of velocity V? under small angle of attack ?. Camber and thickness are small in relation with chord length c. In such case, airfoil can be described with a single vortex sheet distributed over the camber line(Figure 4). Our goal is to calculate the variation of ? s), such that the chamber line becomes streamline and Kutta condition at trailing edge, ? (c) = 0, is satis? ed. 3 Figure 4: Thin airfoil approximation. Vortex sheet is distributed over the chamber line The velocity at any point in the ? ow is the sum of the uniform freestream velocity and velocity induced by the vortex sheet . In order the camber line to be a streamline, the component of velocity normal to the camber line must be zero at any point along the camber line. w ? (s) + V? ,n = 0 , (5) where w ? (s) is the component of velocity normal to the chamber line induced by the vortex sheet and V? n the component of the freestrem velocity normal to the camber line. Considering small angle of atack and de? ning ? (x) = dz/dx as the slope of the chamber line, V? ,n can be written as (Figure 5) V? ,n = V? ? ? dz dx (6) Because airfoil is very thin, we can make the approximation w ? (s) ? w (x) , (7) where w (x) denotes the component of velocity normal to the chord line and can be, using the Biot-Savart law, expressed as c w (x) = ? 0 ? (? )d? 2 ? (x ? ? ) (8) Substituting equations (6), (7) and (8) into (5) and considering Kutta condition, we obtain 1 2? c 0 ? (? )d? dz = V? ? ? x dx ? (c) = 0 undamental equations of thin airfoil theory. 4 (9) Figure 5: Determination of the component of freestrem velocity normal to the chamber line In order to satisfy this conditions , we ? rst transform our variables x and ? into c c x = (1 ? cos ? 0 ) (10) ? = (1 ? cos ? ) 2 2 and equation (9) becomes 1 2? ? 0 ? (? ) sin ? d? dz = V? ? ? cos ? ? cos ? 0 dx (11) with a solution that satis? es Kutta condition ? (? ) = 0 ? (? ) = 2V? A0 ? 1 + cos ? An sin(n? ) + sin ? n=1 (12) In order to ? nd coe? cients A0 and An , we substitute equation (12) into equation (11) and use the following trigonometric relations ? 0 sin(n? ) sin ? ? = cos(n? 0 ) cos ? ? cos ? 0 (13) ? sin(n? 0 ) cos(n? )d? = cos ? ? cos ? 0 sin ? 0 (14) ? 0 and ? nnaly obtain ? dz An cos(n? 0 ) = (? ? A0 ) + dx n=1 5 (15) This equation is in form of a Fourier cosine series expansion for the function dz/dx. Comparing it to the general form for the Fourier cosine expansion we obtain 1 ? dz A0 = ? ? d? 0 (16) ? 0 dx 2 ? dz cos(n? 0 )d? 0 (17) An = ? 0 dx The total circulation due to entire vortex sheet from leading to the trailing edge is c cc ? (? ) sin ? d? (18) ? (? )d? = ?= 20 0 Substituting equation (12) for ? (? ) into equation (18) and carrying out the integration, we obtain ? = cV? ? A0 + A1 (19) 2 hence the lift per unit span, given by Kutta-Joukowski is 2 L? = V? ? = c V? ? A0 + ? A1 2 (20) This equation leads to to the lift coe? cient in form cl = ? (2A0 + A1 ) = 2? ? + 1 ? ? 0 dz (cos(n? 0 ) ? 1)d? 0 dx (21) and lift slope dcL = 2? (22) d? Last two results are important. We can see, that lift coe? cient is function of the shape of the pro? le dz/dx and angle of attack ? , and that even symmetrical wing produces lift, when set under an angle of attack. Lift slope is constant, independently of the shape of the pro? le, while the zero lift angle lS ? ?L=0 = ? 1 ? 0 dz (cos(n? 0 ) ? 1)d? 0 dx (23) depends on the shape. The more highly chambered the airfoil, the larger is ? L=0 2. 3 Vi scid ? ow By now, we have studied the inviscid incompressible ? ow. But in real case, ? ow is viscous. It is time to compare our theoretical results with real one. In Figure 6, we can see variation of lift coe? cient with the angle of attack. 6 At low angles of attack cl varies linearly with ? , as predicted by the theory. However, at certain angle of attack, cl reaches it’s maximum value cl,max and starts to decrease. This is due to viscous e? ect of the ? uid (air). First, the ? w moves smoothly over the airfoil and is attached over most of the surface, but at certain value of ? seperates from the top surface, creating a wake of turbulent ? ow behind the airfoil, which results in drop in lift and increase in drag. Figure 6: Variation of lift coe? cient with the angle of atack. To increase lift of the airfoil, we must increase cl,max . As we have seen, the cl,max of the airfoil primarily depends on it’s shape. Airfoil’s shape can be changed with use of multiele ment ? aps at the trailing edge and slats at leading edge. They increase chamber of the airfoil and therefore its cl,max .The streamline pattern for the ? ow over such airfoil can be seen in Figure 7. 3 Finite wings Properies of airfoils are the same as the properties of a wing of in? nite span. However, all real wing are of ? nite span and the ? ow over ? nite wing is 3 dimensional. Because of higher pressure on the bottom surface of the wing, the ? ow tends to leak around the wing tips. This ? ow establishes a circulary motion that trails downstream of the wing. A trailing vortex is created at each wing tip. These wing-tip vortices induce a small downward component of air velocity, called downwash . It produces a local relative wind which is Figure 7: Flow over multielement airfoil. directed downward in the vicinity of the wing, which reduces the angle of attack that each section of the wing e? ectively sees ?ef f = ? ? ? i (24) and it creates a component of drag, de? ned as induc ed drag. 3. 1 Prandtl’s classical lifting-line theory The idea of lifting line theory, is to use two dimensional results, and correct them for the in? uence of the trailing vortex wake and its downwash. Let’s replace a ? nite wing of span b, with a bound vortex 2 extending from y = ? b/2 to y = b/2. But due to the Helmholtz’s theorem, a vortex ? ament can’t end in a ? uid. Therefore assume the vortex ? lament continues as two free vortices trailing downstream from the wing tips to in? nity(Figure 8). This vortex is due to it’s shape called horseshoe vortex. Downwash induced by such vortex, does not realistically simulate that of a ? nite wing, as it aproaches at wing tips. Instead of representing the wing by a single horseshoe vortex, Prandtl superimposed an in? nite number of horseshoe vortices, each with an in? nitesimally small strength d? , and with all the bound vortices coincident along a single line, called the lifting line.In this model, w e have a continious distribution of circulation ? (y ) along the lifting line with the value ? 0 at the origin. The two trailing vortices in single horseshoe vortex model, have now 2 A vortex bound to a ? xed location in ? ow 8 Figure 8: Replacement of the ? nite wing with single horseshoe vortex. Figure 9: Superposition of an in? nite number of horseshoe vortices along the lifting line. became a continious vortex sheet trailing downstream of the lifting line,and the total downstream velocity w , induced at the coordinate y0 by the entire trailing vortex sheet can be expressed as w (y 0 ) = ? 4? b/2 ?b/2 (d? /dy )dy y0 ? y (25) The induced angle of attack at the arbitrary spanwise location y0 is given by ? i (y0 ) = arctan ?w (y0 ) ?w (y0 ) = , V? V? (26) where we considered V? ? w (y0) and arctan(? ) ? ? for small values of ?. Now we can obtain an expression for the induced angle of attack in term of the circulation distribution along the wing ?i (y0) = ? 1 4? V? 9 b/2 ?b/2 (d? /dy )dy y0 ? y (27) Combining results cl = 2? (y0) V? (28) and cl = 2? [? ef f (y0 ) ? ?L=0 ] (29) for coe? cient of lift per unit span from thin airfoil theory, we obtain ? ef f = ?(y0 ) + ? L=0 ?V? c(y0 ) (30)Substituting equations (27) and (30) into (24), we ? nally obtain the fundamental equation of Prandtl’s lifting line theory. ? (y 0 ) = 1 ?(y0 ) + ? L=0 (y0 ) + ?V? c(y0 ) 4? V? b/2 ?b/2 (d? /dy )dy y0 ? y (31) Just as in thin airfoil theory, this integral equation can be solved by assuming a Fourier series representation for the distribution of vorticity N An sin n? ?(? ) = 2bV? (32) n=1 where we considered transormation y = (? b/2) cos ? , with 0 ? ? ? ? and coe? cients An must satisfy Equation (31). With such vorticity distribution, Equation (31) becomes ?(? 0 ) = N N 2b sin n? 0 nAn An sin n? 0 + ?L=0 (? 0 ) + ?c(? 0 ) n=1 sin ? 0 n=1 (33) The total lift distribution is obtained by integrating equation for lift distribution over the span L= b/2 ?b/2 V? ?(y )dy (34) C oe? cients of lift and induced drag3 , can be calculated via equations CL = and CD = 2 L = q? S V? S D 2 = q? S V? S 3 b/2 ?(y )dy (35) ?i (y )? (y )dy (36) ?b/2 b/2 ?b/2 Note the di? erence in nomenclature. For 2D bodies, coe? cients have been denoted with lowercase letters. In 3D case, we use capital letters 10 respecteviliy. Considering expressions (32) and (33), they can be written as CL = A1 ? AR (37) and 2 CL (1 + ? ) (38) ?AR here AR is aspect ratio of ? nite ? ng, de? ned as AR = b2 /S , and ? = N 2 2 (An /A ? 1) . Note that CL depends only on the leading coe? cient in Fourier series expansion and that ? ? 0. Therefore, the lowest induced drag will be produced by a wing where ? = 0, that is, n = 1. Such circulation distribution is given by ? (? ) = 2bV? A1 sin ? and is known as elliptical circulation distribution CD,i = 4 Ground e? ect The main di? erece between wing application in aviation and car racing is, that cars are in contact with the ground. Therefore, wing experien ces some additional e? ects due to ground proximity.Remember the wing tip vortices we mentioned at the beginning of the previous section. They do nothing but harm, as they increase drag and decrease lift at given angle of attack. When ?ying near to the ground, the ground partially blocks(Figure 10) the trailing vortices and decreases the amount of downwash generated by the wing. This reduction in downwash increases the e? ective angle of attack of the wing so that it creates more lift and less drag than it would otherwise. This e? ect is greater, the closer to the ground the wing operates. Figure 10: E? ect of the ground proximity on creation of the trailing vortices.Another way to create downforce is to create low pressure area underneath the car, so that the higher pressure above the car will apply a downward force. The area between car’s underbody and the ground, can be thougth as an example of Venturi nozzle. The Venturi e? ect may be derived from 11 a combination of Bern oulli’s principle and the equation of continuity. The ? uid velocity increases through the constriction to satisfy the equation of continuity, while it’s pressure decreases due to conservation of energy. The gain in kinetic energy is supplied by a drop in pressure.The main advantage of ground e? ect is, that it produces almost no drag. 5 Applications in car racing Now summarize what we have learned so far. The coe? cient of lift increases with increasing angle of attack. At some angle, ? ow seperates from the wing, which causes drop of lift coe? cient. With use of multidimensional ? aps, we increase chamber of the airfoil and thus maximum coe? cent of lift. In 3 dimensional case, vortices appear at wing tips. They reduce wing’s e? ciency and increase drag. The lowest drag can be achieved with elliptically shaped wing. Dimensions of the wing are also important.Wing with greater surface, produces more lift and wing with higher aspect ratio induces less air resista nce. In the next sections, we will see, how engineers used this principles at developing the main aerodynamical parts of racing cars. 5. 1 Rear wing First rear wing appeared in 1966, when Jim Hall equiped his Chaparral 2E with a rear wing. From then on, use of wings grew quickly. First wings were mounted high over the rear end of the car to operate in indisturbed ? ow. They were also mounted on pivots, so the driver was able to change the angle of attack during the ride. High mounted wings often broke o? uring the race and were therefore prohibited by FIA. In Formula 1, wings were ? rst introduced in 1968 at the Belgium grand prix, when Ferrari used full inverted rear wings, and Brabham did likewise, just one day after the Ferrari’s wings ? rst appeared. Modern rear wings produce approximately 30-35 % of the total downforce of the car. A typical con? guration(Figure) consists of two sets of airfoils connected to each other by the wing endplates. The most downforce is provided by the upper airfoil. To achieve the greatest possible lift coe? cient, it consists of multiple high aspect ratio elements, which prevent ? w separation. Angle of attack depends on circuit con? guration. On tracks with many turns, more downforce is needed, therefore the wing is set at higher angle of attack. Conversely, on tracks with long straights, wing has small angle attack, thus reducing air drag and allowing higher top speeds. Lower airfoil section ac12 Figure 11: Chapparal 2E (left) and Ferrari 312 (right). tually reduces the downforce produced by total rear wing, but it creates a low-pressure region just below the wing to help the di? user4 to create more downforce below the car. Ususally it consists of two elements.Another important part of rear wing are endplates . They provide a convenient way of mounting wings, but also have aerodynamic function. They reduce the 3D e? ect of the wing by preventing air leakage around the wing tips and thus formation of trailing vortices. An additional goal of the rear endplates is to help reduce the in? uence of up? ow from the rear wheels. The U-shaped cutout from the endplate further alleviates the development of trailing vortices. 5. 2 Front wing The front wing on the car produces about 1/3 of the car’s downforce and it has experienced more modi? ations than rear wing. It is the ? rst part of the car to meet the air mass, therefore, besides creating downforce, it’s main task is to e? ciently guide the air towards the body and rear of the car, as the turbulent ? ow impacts the e? ciency of the rear wing. Front wings appeared in Formula 1 just two weaks after the ? rst rear wings, on Lotus 49B. First front wings were quite simple with single rectangular airfoil with ? at vertical endplates to reduce wing tip vortices. First improvement appeared in 1971, with so-called Gurney ? ap. This is a ? at trailing edge ? p perpendicular to the chord and projects about 2% of the chord. It can improve the perfor mance of a simple airfoil to nearly the same level as a complex design. The same year, the concept of elliptical wing was applied. March equiped it’s 711 with elliptical front wing. Two years later Ferrari avoided wing-body interaction with wing mounted quite far ahead 4 See section 5. 3 13 Figure 12: Modern rear wing consists of upper(2) an lower(3) airfoil section mounted on endplates (1) with U-shaped cutout (4). from the body. Multi element wings were introduced in 1984 by McLaren.The angle of attack of the second element was allowed to be modi? ed so that the load applied on the front wing could be changed to balance the car according to the driver’s wishes. In 1990 Tyrell raised the nose of it’s 019 to increase the ? ow under the nose cone and improve ? ow conditions under the car. This concept avoids wing-body interaction and allows the front wing to operate in undisturbed ? ow. It also enlarges e? ective area of the wing. After Imola 1994, the FIA regula tions do not allow any chassis parts under a minimum ground height. This clearance is di? erent between the centre and the side of the car.Teams used this to curve front wing in the centre of the span and regain some of the lost ground e? ect. In 1998, regulations decreased the width of Formula 1 car, so the front wings overlapped the front wheels. This created unnecessary turbulence in front of the wheels and reducing aerodynamic e? ciency of the wing. With reducing wing’s span this could be avoided, but it would also decrease wing’s aspect ratio. Insted this, teams use wing tips to direct the air around the wheels. 14 Figure 13: Con? guration of modern front wing. Two element airfoil (1 & 2) is mounted under the nose of the car (5).Endplates (4) direct air around the wheels and curved area (4) under the nose increases wing’s e? ciency. 5. 3 Ground e? ect The second revolution in Formula 1 aerodynamics occurred about a decade after the ? rst, with the introucti on of the Lotus T78 in 1977. Lotus T78 and it’s further development, Lotus T79, were ? rst cars to use ground e? ect. The underbody took shape of inverted wing pro? le(Figure). The decreasing crosssectional area accelerated the air? ow and created low pressure underneath the car. The gap between the bottom of the sidepods and the ground was sealed with so-called sidepods. They helped to maintain 2D ? w characteristics that provide increased downforce and reduced drag, compared to a typical 3D wing. Skirts enabled very high cornering speeds and were prohibited by the rules, due to safety reasons and from 1983 onwards, the tehnical regulations in Formula 1 require the underbody panel between the wheels to be completely level. The ? ow wolume between the vehicle and the ground is strongly dependent on the car’s attitude relative to the ground. This correlation is illusrtated in Figure. Very small ground clearence results in positive lift, since there is almost no air? ow between the underbody and the ground. With in- 15Figure 14: Some historical milestones in front wing develpment. Lotus 49B, March 711, Ferrari 312 T2 and Tyrrell 019. Figure 15: Lotus T79 and sketch of it’s underbody creasing ground clearence the air? ow produces low pressures causing overall lift to be lowered to negative values and then to rise again as ground clearence continues to increase. This is due to the fact that the ? ow velocity under the car decreases as ground clearence increases. More downforce can be generated using a di? usor between the wheels at the rear of the car. The air enters the di? user in a low-pressure, high-velocity state after accelerating under the 16 ar. By gradually increasing the cross-sectional area of the di? user, the air gradually slows down and returns to its original free-stream speed and pressure. The di? user’s aim is to decelerate the air without it separating from the tunnel walls, which would cause a stall, reducing the down force and inducing a large drag force. By installing an inverted wing close to the di? user exit 5 it is possible to create a low-pressure area, which essentially sucks the air from the di? user. The di? user and wing combination permits a higher air mass ? ow rate through the di? user, thus resulting in higher downforce.Sharp edges on the vertical tunnel walls generate vortices from entrained air and help con? ne the air through the di? user and reduce the chance it will separate. Figure 16: Correlation between lift coe? cient and ground clearence(left) and di? user on Ferrari F430(right) Again Chaparral, showed completely new way to create downforce. The Chaparral 2J in 1969 used two rear fans to suck in air from under the car, thus creating low pressure under the car. Big advantage of this concept is, that downforce can be generated independently of the speed. Fans were also used in Formula 1. Brabham BT46 used a rear mounted fan driven o? he gearbox. It won it’s debut rac e in 1978, but was promptly banned by the governing body. Barge boards were ? rst seen in 1993 and their purpose is to smooth the air? ow around the car and into the radiator intakes. They are most commonly mounted between the front wheels and the sidepods (See Figure) . Their main purpose is to direct relatively clean air into the sidepods. Clean air is from the low section of the front wing where air? ow is fairly una? ected 5 See rear wing section 17 Figure 17: Two cars which used fans to create downforce. The Chaparral 2J â€Å"sucker car† (left) and Brabham BT46 â€Å"fan car† y the wing and far away from tires, which may throw stones and debris in to the radiator. Bargeboards also produce vortices, to seal the area between the sidepots and the surface. They work as a substitude for skirts. Figure 18: Bargeboards on McLaren MP4/8 6 Conclusion References [1] J. D. Anderson; Fundamentals of Aerodynamics 18 [2] Applied Aerodynamics: A Digital Textbook, http://www. de sktopaero. com/appliedaero/preface/welcome. html [3] W-H Hucho: Aerodynamics of Road Vehicles [4] Peter Wright: Formula 1 Technology [5] Milliken,Milliken: Race Car Vehicle Dynamics [6] F. Mortel: Cran? eld Team F1: The Front Wing 19

Short Term and Long Term Financing

Short Term Finance What is Short Term Financing? Short term financing is basically refers to additional money for a business which requires for running its business for short terms which is usually a period of one year. There are some sources of short term finance which are as following:- Overdraft Overdraft bank basically means a facility that the bank provides to its customers where the customer is given permission to draw money from the banks in surplus of their balance in their heir bank accounts.When taking overdraft from the bank, the account must be zero to get extras extension of money and the interest rate will be very high and we have to pay back the bank in a very short period of time. Trade Credit Trade credit refers to buying products and servicers of a business which needs in the course of its business on credit, depending on the trade practices prevalent in a particular industry, the nature of the business relationship between the supplier and the company may give a di fferent time period to pay the products and services they buy from different suppliers.Exactly as companies get their credit from their suppliers, they must also give credit to their customers. The customers are given 50 to 60 days to pay up the bills. After 60 days, interest will be applied on the customers. If the customers are unable to pay, the will be asked for installment plan. Bank Loans Bank Loan means loans which are given to banks which need to repaid their installment over a fixed period of time which may be short or long term period. Even though it is called bank loans, these loans can be move forward by banks or other financial institution.Usually loans like this are generally given for a certain reason such as purchases of capital equipment. Advantages/ Disadvantages of Short Term Finance Short term financing is a method to raise funds which involves financial responsibility that is needed to be repaid within a year or less. Short term financing is flexible and a fast way for companies to obtain working capital for their daily operations. The main disadvantage is that a company may be too dependent on short term funds and threatened to high banking fees and interest rate.This will may affect the profit margins. Speed Short-term loans can be achieved much fast and easier compared to long-term financing. Lenders will not make through an examination of the company’s account for short-term lending compared to the case they do for long-term loans. Medium size companies do not have large amount of cash and are vulnerable to sudden financial shocks such as non-payment by a key debtor. Flexibility Small companies usually have seasonal variations in the cash and need access to capital over that period.Overdraft protection is one of the form of short term finance where the bank agrees to pay the company’s cash withdrawals, checks, and electronic debits to a certain limit. The lender will charge a fee for this facility on any balance outstandi ng. The cost of short term finance may be lesser compared to the long term finance where the cost may be higher. Drawback to this type of short-term finance flexibility is that the bank can withdraw the overdraft protection in a short notice. Risk Market circumstances, such as retreat, may cost the small businesses into borrowing a large amount on a short term basis.Short term finance can be a risk factor for the borrower A short term loan can be renewed by the lender on a certain terms than the original contract. This does not only cause the businesses to face a high cost of capital, it may not be able to service the amount of debt collected. This will put the company in a weak position where it could cause the company to be bankrupt. Management Lenders who extend their short term financing does not involve themselves in the business decisions about capital investment.Long-term finance is associate by the number of provisions, such as caps on the salaries of the companies principal s or limits on other financial arrangements, which will restrict the business actions. Long-term Finance What is long-term finance? Long term finance is basically holding an asset for a long period of time. Providing the type of security and a long-term asset can be hold as short as 1 year or as long as 25 years or more. Long-term finance also means funding which are obtained for a time frame exceeding the duration of one year.When business borrows money from a bank using long term finance methods, it will be expecting the loan to be paid back more than one year. Example, making payments on a 20 year mortgage. Long -term finance are usually for expansion of new markets, purchases of assets such as machinery, land and buildings and business growth through the acquisition of other businesses or properties. Its types of long term finance are as following :- Venture capital Venture capital is becoming an increasingly important source of finance for growing companies.Venture capitalists are generally very wealthy groups of companies or individuals which specifically set up for investment in developing companies. Venture capitalists are usually on the look out for companies with have potential. They are ready to offer money to help businesses to grow, in return the venture capitalist get some ownership of the company as well as share in the profits made. Venture capitalists usually are prepared to take projects which have a high risk and which some banks might not wan to get involve in.The advantage of this might be heavier because the possibility of the businesses losing some of their independence in making a decision. Example of venture capitalists who are also called as private equity firms are Hermes Private Equity Debentures If a company wants to borrow a big amount of money for a long but fixed period of time, it can borrow from the general public by issuing loan certificates called Debentures. The total amount borrowed is divided into units of fixed amount. T hese are debentures are usually offered to the public to subscribe in the same manner as it is done in the case of shares.A debenture is issued under a seal of the company. It is written for acknowledgement of money borrowed. It also specifies the terms the terms and conditions such as security offered, rate of interest and time repayment. There few types of debentures which are as following :- 1. Redeemable debentures and irredeemable debentures Redeemable debentures These are debentures which are repayable on a pre-arranged date or any time depending to their maturity provided the company wish and gives a notice to that effect. Irredeemable DebenturesThese irredeemable debentures are also called perpetual debentures. A company is not bounded to repay the amount during the period of time given. If the issuing company fails to pay the interest, it has to reclaim such debentures 2. Convertible Debentures and Non-convertible Debentures Convertible Debentures The holders of these conve rtible debentures are given the options to convert their convertible debentures into equity shares and ratios as decided by the company. Non-Convertible Debentures These non-convertible debentures cannot be converted into sharesMortgage Mortgage is a loan specifically for the purchase of a property. Usually businesses do not buy property through a mortgage. Mortgages are usually used as a security for a loan. This tend to happen with smaller businesses. Example, A sole trader running a florist shop might want to shift to a larger premise. They will find a shop with a price of $100,000. To give this sort of money, the bank will want to have some sort of security as a guarantee that if the borrower cannot pay back the money to the bank, the bank will be able to get back their money.The borrower can use their own property as a security for the loan, it is called taking out a second mortgage. If the business is not able to pay back the bank the loan then the bank has the right to take t he house and sell it to recover their money. Using mortgage this way is a good way of rising finance for small businesses but it also carries a big risk. Advantages/ Disadvantages of Long-term finance Stability If we have a long term financing, that means we have a stability and no need to search for financing often compared to short term financing.This also means that it will be easier to project our cash flows and earnings as we will know our expenses every month. Short term financing does not offer these advantages, because we have to constantly renegotiate the terms of our agreement. Cost of Capital Having a long term financing gives us a better idea of the long term cost of capital. By this way we will have a better understanding on which projects are worth pursuing or not. IF we don’t have long term financing in place, our cost of capital may change all our negotiation of our terms.This will lead us to more confusion in figuring out what kind of profitability we are loo king for in a project. Differences between short term and long-term finance Duration Most of the short-term financing occur over short period of one year, even though some of the sources can last up to three years or more. However long-term financing is like home mortgage which usually have a longer period of time up to 30 years. Interest Short-term financing is repaid over a short period of time, the interest cost to borrow the money will be smaller.However, long-term sources such as Bank loans which have high interest rate due to the amount of time taken to repay the capital. Types Short-term and long-term sources of financing differ in instrument type. Example of short-term sources includes leases, short-term commercial loans, account payable and bank overdraft coverage. However example of long-term sources includes retained earnings, finance leases, venture capitals and company shares Which one is more preferable to choose short term or long-term finance?Conclusion, it would be generally be better to choose short-term loan over a long term finance if the school Halls Creek High school budget allows it. This will increase the monthly payments as much as possible to take advantage of the lower interest rate. The combination of bigger the monthly payment and smaller interest rate will allow the school to have a bigger payment on the outstanding balance. This will help the school to pay less interest on the loan taken and end their mortgage sooner. .

Tanglewood Case 2 - 1334 Words

Christian April 6, 2014 Wk 2 Dropbox Assignment TangleWood Case 2 Currently the organization expects that their forecast for labor requirements is essentially constant from the previous year. Based on this assumption complete the five stages of the planning process: Currently the organization expects that their forecast for labor requirements is essentially constant from the previous year. This means the forecast for next year will be taken as given. Fill in the empty cells in the forecast of labor availabilities in Table 1.1 Table 1.1 Markov Analysis Information Transition probability matrix Current year (1) (2) (3) (4) (5) Exit Previous year (1) Store associate 0.53 0.06 0.00 0.00 0.00 0.41 (2) Shift leader 0.00 0.50†¦show more content†¦Develop a preliminary statement of the action plan for hiring for Washington next year. This should be an overview of the number of individuals needed to meet projected staffing levels for various positions that can be given to store managers. Make sure that your recommendations take the strategic staffing levels issues from the introductory case into account. According to labor requirements found in table 1.1, next year we will need to hire 4,505 store associates. Since Tanglewood promotes within, we will need 600 shift leaders, 493 department managers, 69 asst. store managers and 49 store managers. Based on our current numbers we will have to hire a significant number of new store associates. Below is the plan for our new hires. we will have to increase our base pay and offer more flexibility. We will allow associates to cross train in completing a variety of task and promote teamwork through an awards system. We will be more consistent in recognizing that the sales associate is a valuable assets to the company.l also work toward developing talent and hiring internally. For employees, such as recent college graduates, who have expressed a desire to attain managerial positions, we will allow them to enter a management trainee program. This program will follow our policies of having everyone start at the bottom, but it will allow par ticipants to move up quickly in theShow MoreRelatedTanglewood Case 21018 Words   |  5 PagesLabor 2. Markov Analysis Information 3. Demographic Categories 4. Promotion Practices 5. Organizational Memo Forecast of Labor: MGT Consulting gathered information from the previous year (2010) and used a Markov analysis to generate a plan of action for the employment needs for Tanglewood in 2011. The Washington market is very stable for Tanglewood and we decided that the current workforce will be sufficient for the 2011 forecast. There are 10750 current employees in the Tanglewood storesRead MoreTanglewood Case 21193 Words   |  5 Pages Christian April 6, 2014 Wk 2 Dropbox Assignment TangleWood Case 2 Currently the organization expects that their forecast for labor requirements is essentially constant from the previous year. Based on this assumption complete the five stages of the planning process: Currently the organization expects that their forecast for labor requirements is essentially constant from the previous year. This means the forecast for next year will be taken as given. Fill in the empty cells in the forecastRead MoreEssay on Tanglewood Case 21373 Words   |  6 PagesCase 2 Specific Assignment Details For the store manager group, you will analyze the information and prepare a report showing the results of the Markov analysis and the EEO investigation. The Director asked you to address these questions in your written report: 1. 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Harris HRM594-Strategic Staffing Mr. Perrone, I am responding to your request to review Tanglewood’s staffing decisions currently in place. After reviewing Tanglewood’s 39 year history as well as current and potential competitors, I have reviewed the 13 sections per your request. Each recommendation is based on Tanglewood’s mission and values. Tanglewood is a 39 year old company looking to expand its’ organization while still maintaining its’Read MoreTanglewood Case Two1215 Words   |  5 PagesTanglewood Case 2 Strategic Staffing (HR 594) Summer Session B comronf@gmail.com TANGLEWOOD CASE TWO ATT: Daryl Perrone After analyzing the data and performing an environmental scan it is clear that the demographics of Spokane, Washington will present you will problems filling vacancies based on the Equal Employment Opportunity requirements. Spokane is the second largest city in Washington and according to my research 84% of these people are white. 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