92 research outputs found

    Happiness Institutions

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    Bakhjulsstyrning av fordon Ă€r en möjlig konfiguration som lite glömts bort inom fordonstekniken. Tidigare arbeten inom Ă€mnet bakhjulsstyrning Ă€r vĂ€ldigt detaljerade och snĂ€va i sin analys. I detta arbete vill författaren visa en bakgrund till hur olika farkoster styrs samt analys av detta. Syftet med arbetet Ă€r att utifrĂ„n litteratursökning och intervjuer kunna besvara vilken inverkan drivkĂ€llans placering och de konceptuella skillnaderna mellan olika farkoster har pĂ„ styrningens placering. Samt vilka förvĂ€ntade egenskaper en farkost fĂ„r med icke konventionell styrning. Med hjĂ€lp av en simulering i MATLAB Ă€r syftet att kunna besvara vilken roll massa, hastighet och axellĂ€ngd spelar för ett bakhjulsstyrt fordon och hur responsen ser ut jĂ€mfört med ett framhjulsstyrt fordon. Resultatet frĂ„n intervjuerna och litteraturen visar att drivkĂ€llans placering nĂ€ra rodret Ă€r vĂ€ldigt viktig för fartygs styrningsförmĂ„ga. DĂ€remot för flygplan pĂ„verkar det mest lastförmĂ„ga och för fordon tyngdpunktens placering. De konceptuella skillnaderna visar pĂ„ att större fordon har mer att vinna pĂ„ fyrhjulsstyrning dĂ„ en mindre vĂ€ndradie Ă€r merkritiskt för dessa och att flygplan som flyger i överljudsfart behöver andra vinguppsĂ€ttningar. För fartyg har det visat sig att en liten vĂ€ndradie Ă€r viktigt i hamnomrĂ„den och att bĂ„de stora och smĂ„ fartyg dĂ„ anvĂ€nder sig av bogpropellrar. De förvĂ€ntade egenskaperna för en ickekonventionell styrning Ă€r frĂ€mst negativ för fordon och fartyg, dĂ„ det finns risk för instabilitet och överstyrning, medan flygplan redananvĂ€nder sig av styrningen fram i form av nosvingar. Simuleringarna visar att ett bakhjulsstyrt fordon bör ha en hastighetsbegrĂ€nsning dĂ„ det blir svĂ„rkontrollerat i höga hastigheter över 50km/h. En större massa har visat sig hĂ€mma magnituden av den laterala accelerationen en i fel riktning och en lĂ€ngre axellĂ€ngd minskar rotationshastigheten kring gir-led. Resultaten visar ocksĂ„ att ett bakhjulsstyrt fordon har en fördröjning av den laterala accelerationen jĂ€mfört med ett framhjulsstyrt fordon pĂ„ 0,1-0,2 sekunder beroende av bland annat massa, axellĂ€ngd och hastighet. Responstesten visar att denna fördröjning bidrar till att den laterala förflyttningen Ă€r fördröjd första sekunden för hastigheter 10-90km/h men att redan efterytterligare 1,5 sekunder Ă€r den dubbel sĂ„ stor för hastigheter 50-90km/h. Slutsatsen Ă€r att fordon inte har bakhjulsstyrning i höga hastigheter pĂ„ grund av den fördröjda responsen i början samt av att utslaget efter nĂ„gra sekunder blir vĂ€ldigt mycket kraftigare vilket gör fordonet svĂ„rt att kontrollera.Rear wheel steering of vehicles is a possible steering, which has been forgotten in vehicle design. Earlier works show only details concerning one vehicle type from this subject. In this work the author will first present a background to how different vehicles are steered and then the analysis of it. The purpose with this paper is to from literature and interviews answer to which impact the placement of the engine and the conceptual differences have on the steering from different vessels. It will also answer which anticipated properties the steering will have if itÂŽs not placed in a conventional way. Through simulation in MATLAB the paper will answer to which degree mass, velocity and length of axle influences steering behaviour of a rear wheal steered, RWS, car and how the steering response is different to a front wheal steered car, FWS. The result from the literature and the interview shows that placement of engine and propeller near the rudder is very important for a ships steering capability. For vehicles it has most effect on the centrum of gravity, which is to prefer in middle of the vehicle,and for airplanes the ability to place cargo. The conceptual differences shows that a larger vehicle has more to gain, if it is equipped with four wheel steering, due to turning radius is a more critical aspect. For airplanes in super sonic speed it reveals that they need another set of wings. Ships need a smaller turning radius in harbours and all size of ships then use thrusters. The properties of a vessel with not conventional steering are most negative for cars and ships because of risk for oversteering and instability, while for airplanes its already in use in form of canard wings. The simulations display that rear wheel steered vehicle should have a limit of velocity because of its behaviour in high speeds over 50 km/h. A larger mass has shown todepress the magnitude of lateral acceleration in wrong direction and a larger length of an axle is shown to depress the yaw-rate. The result also displays that a RWS vehicle has a delay of the lateral acceleration compared to a FWS vehicle with approximately 0,1-0,2 seconds depending on mass, velocity and length of axle. The test of response indicates that this delay contributes to the delay of the lateral movement of the vehicle the first second for speeds between 10-90 km/h, but after only 1,5 seconds further thelateral movement is twice the value for speeds 50-90km/h. The conclusion is that vehicle doesn’t have RWS due to the delay in response in the beginning and the very larger lateral movement after only seconds later, which makes the vehicle hard to control

    Evaluation Research and Institutional Pressures: Challenges in Public-Nonprofit Contracting

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    This article examines the connection between program evaluation research and decision-making by public managers. Drawing on neo-institutional theory, a framework is presented for diagnosing the pressures and conditions that lead alternatively toward or away the rational use of evaluation research. Three cases of public-nonprofit contracting for the delivery of major programs are presented to clarify the way coercive, mimetic, and normative pressures interfere with a sound connection being made between research and implementation. The article concludes by considering how public managers can respond to the isomorphic pressures in their environment that make it hard to act on data relating to program performance.This publication is Hauser Center Working Paper No. 23. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

    Annual Bibliography

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    The Trouble with Cases

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    For several decades now a debate has raged about policy-making by litigation. Spurred by the way in which tobacco, environmental, and other litigation has functioned as an alternative form of regulation, the debate asks whether policy-making or regulation by litigation is more or less socially desirable than more traditional policy-making by ex ante rule-making by legislatures or administrative agencies. In this paper we step into this debate, but not to come down on one side or another, all things considered. Rather, we seek to show that any form of regulation that is dominated by high-salience particular cases is highly likely, to make necessarily general policy on the basis of unwarranted assumptions about the typicality of one or a few high-salience cases or events. Two cornerstone concepts of behavioral decision--the availability heuristic and related problems of representativeness--explain this bias. This problem is virtually inevitable in regulation by litigation, yet it is commonly found as well in ex ante rule-making, because such rule-making increasingly takes place in the wake of, and dominated by, particularly notorious and often unrepresentative outlier events. In weighing the net advantages of regulation by ex ante rule-making against those of regulation by litigation, society must recognize that any regulatory form is less effective insofar as it is unable to transcend the distorting effect of high-salience unrepresentative examples.

    Monetizing the Benefits of Risk and Environmental Regulation

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    This article provides a response to the opponents of monetization of risk and environmental benefits, such as the authors of Priceless: On Knowing the Price of Everything and the Value of Nothing . Putting benefit values in dollar terms ensures that there will be full recognition of these benefits in the policy evaluation process, and also places them on terms comparable to program costs. Much of the article is devoted to advocating the use of the value of statistical life to value health risk reductions from government regulations. The article explores sensitive issues such as the heterogeneity of the value of statistical life with respect to income and age. While the use of a "senior discount" was controversial and involved too great of a discount, there is substantial evidence that there are age variations in the value of statistical life. The article also advocates the continued use of stated preference approaches to valuing environmental benefits, which is in contrast to the critiques of stated preference analyses by those who consider environmental resources to be priceless and by those who believe that all non-use values of environmental benefits are zero.
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