The analysis and design of transonic two-element airfoil systems

The multiphase effort in the development of tools for the analysis and design of two-element airfoil systems, that is, airfoils with a slat or a flap at transonic speeds is described. The first phase involved the development of a method to compute the inviscid flow over such configurations. In the second phase the inviscid code was coupled to a boundary layer calculation program in order to compute the loss in performance due to viscous effects. An inverse code that constructs the airfoil system corresponding to a desired pressure distribution is described

The Senate and Supreme Court Nominations: Some Reflections

Sammanfattning Vad är en transformation, och vad den kan vara? Hur kan en strategi för hur man kan förhålla sig till transformationsprojekt se ut? Jag har definierat det som att en transformation handlar om att ta en befintlig byggnad och införa ett nytt program som skapar en ny verklighet. Det kan finnas flera anledningar till att göra en transformation istället för att bygga nytt. Den viktigaste anledningen som jag har valt att arbeta med handlar om att fånga upp de värden som finns i en byggnad och få med sig dem och bygga vidare på dem istället för att skapa helt andra värden. Värden är saker som yta, volym, rumshöjd, ljusförhållanden, material och detaljer. Det är saker som de gjutna betongtrapporna och de speciella fönsterpartierna i byggnaden. För mig är det detta som är själva idén och meningen med en transformation. För värdena som bevaras knyter an till historien och bär och bevarar minnen och identiteter. De skapar en kontinuitet i byggnadens berättelse. I en transformation uppkommer en mängd stora konflikter eftersom det nya programmet efterfrågar värden som byggnaden saknar. Hur man väljer att lösa dessa konflikter är det mest kritiska och svåraste i en transformation. Jag gör transformationen i två steg. Det första steget går ut på att definiera så mycket värden som möjligt och försöka få med dem in i det nya programmet samtidigt som jag bortser något från helheten. Boendena fanns där sedan tidigare, för mig handlade det bara om att isolera värdena och föra med dem in i det nya programmet. Jag har behållit så mycket av det befintliga som möjligt för att hålla värdena intakta och bara lagt till väggar för att avgränsa lägenheterna. Det jag då får är väldigt speciella boenden, många har egna ingångar, breder ut sig i två plan och har ljusinsläpp från två håll. Det här är ett säkert och relativt enkelt sätt att bevara värden. När dessa bevarade boenden är definierade uppkommer de svåra konflikterna som också gör transformationen så pass intressant. Ytorna som är kvar efter att jag lagt ut dessa behållna boenden är svåra att skapa bra boenden ifrån. Jag tror att det är viktigt att tilläggen som måste till i en transformation anknyter till byggnaden som var. Annars är risken stor att värdena som fanns förstörs. Anknytning handlar för mig om att det nya tar upp saker som rumsliga koncept, formmässiga, materialmässiga eller strukturella koncept. Innergårdarna som finns där idag används dåligt. Egentligen är innergårdar något fantastiskt. De drar inte bara in solljus utan även skugga, regn, snö, ljud, växtlighet, insekter och fåglar djupt in i en byggnadsvolym. Därför har jag valt att utveckla de innergårdar som redan finns genom att lägga till några fler. I och runt kring skolan finns också flera platsgjutna betongtrappor. För att skapa förbindelser har jag lagt till nya liknande trappor. En bra transformation skapar förutsättningar för ett nytt behov samtidigt som den behåller de viktigaste värdena i en byggnad och bygger vidare på identiteten istället för att förstöra den. Min strategi för transformationer i två steg handlar om att först få med sig vissa speciella värden in i ett nytt program utan att ta hänsyn till byggnaden som helhet. Därefter skapas ett tillägg som relaterar till det befintliga men samtidigt löser de konflikter som alltid uppkommer vid en transformation. Resultatet i det här fallet är boenden som är väldigt speciella jämfört med boenden som normalt byggs idag. Det är inga typlägenheter utan boendena som skapas har ytor, volymer, detaljer och andra egenskaper som nybyggda boenden sällan har.  Abstract What is a transformation, and what could it be? How could a strategy for how to approach a transformation project look? I have defined a transformation as the act of taking an existing building and inserting a new program that creates a new reality. There can be many reasons to do a transformation instead of building something new. The most important reason that I have chosen to work with is about capturing the qualities or values that exists in a building and bring them into the new reality and build on them instead of creating whole different values. Values in this case are things like surface area, volumes, height, light conditions, material and details. It is things like the cast concrete stairs and the very special windows in some parts of the building. To me this is the core idea and purpose of any transformation. Because the values that are kept ties the present to the history, and carries and keeps memories and identities. They create continuity in the story of the building. In a transformation a number of mayor conflicts arise because the new program demands values that the existing building lacks. How you chose to solve these conflicts is the most critical and most difficult aspect of any transformation. My transformation is done two steps. The first step is about identifying as much values as possible and trying to bring them into the new program while overlooking the whole. The dwelling was there already, all I had to do was isolate the values and bring them in to the new program. I have kept as much of the existing material as possible to keep the values intact and only added walls to define the new apartments. The result is very particular dwellings; a lot of them have their own entrances, they are spreading out both horizontally and vertically and have sunlight from two directions. This is a safe and rather easy way of keeping values. When these kept dwellings are defined the more difficult conflicts arises that makes the transformation so interesting. The surface areas that remain after I have laid out these kept dwellings are hard to create good dwellings from. I think it’s important that the additions that has to be made in a transformation relates to the building that used to be. Otherwise there´s a great risk that the existing values are destroyed. Relation for me is about picking up things like spatial concepts and concepts relating to form, material or structure. The courtyards that exist today are rarely in use. Courtyards are actually something amazing. They don’t only retract sunlight but also shadow, rain, snow, sounds, foliage, bugs and birds deep into a building. Therefore I have chosen to develop the courtyards that already exists by adding some more. In and around the school there are also several stairs in cast concrete. To create connections I’ve added new similar stairs.   A good transformation creates the conditions needed for a new demand, while keeping the most important values in a building and adds to the identity instead of destroying it.   My strategy for transformations in two steps is about first bringing certain special values into a new program without considering the building as a whole. Afterwards an addition is created which relates to the existing while solving the conflicts that always arise when doing a transformation. The result in this case is dwellings that are very particular compared to the dwellings which are usually built today. They are not standard flats but dwellings with surface areas, volumes, details and other characteristics that newly built dwellings rarely has

Environmental Impacts of a North American Free Trade Agreement

A reduction in trade barriers generally will affect the environment by expanding the scale of economic activity, by altering the composition of economic activity, and by bringing about a change in the techniques of production. We present empirical evidence to assess the relative magnitudes of these three effects as they apply to further trade liberalization in Mexico. In Section 1. we use comparable measures of three air pollutants in a cross-section of urban areas located in 42 countries to study the relationship between air quality and economic growth. We find for two pollutants (sulfur dioxide and "smoke") that concentrations increase with per capita GDP at low levels of national income, but decrease with GD? growth at higher levels of income. Section 2 studies the determinants of the industry pattern of U.S. imports from Mexico and of value added by Mexico's maquiladora sector. We investigate whether the size of pollution abatement costs in the U.S. industry influences the pattern of international trade and investment. Finally, in Section 3, we use the results from a computable general equilibrium model to study the likely compositional effect of a NAFTA on pollution in Mexico.

Sovereign Debt as a Contingent Claim: Excusable Default, Repudiation, and Reputation

History suggests the following stylized facts about default on sovereign debt:(1) Defaults are associated with identifiably bad states of the world. (2) Defaults are usually partial, rather than complete.(3) Sovereign states usually are able to borrow again soon after a default. Motivated by these facts, this paper analyses a reputational equilibrium in a model that interprets sovereign debts as contingent claims that both finance investments and facilitate risk shifting. Loans are a useful device to facilitate risk shifting because they permit the prepayment of indemnities. Nevertheless, because the power to abrogate commitments without having to answer to a higher enforcement authority is an essential aspect of sovereignty, a decision by a sovereign to validate lender expectations about debt servicing depends on the sovereign's concern for its trust worthy reputation. A trustworthy reputationis valuable because it provides continued access to loans. A key aspect of the analysis is that lenders differentiate excusable default, which is associated with implicitly understood contingencies, from unjustifiable repudiation. In the reputational equilibrium, the short-run benefits from repudiation are smaller than the long-run costs from loss of a trustworthy reputation. Thus, although sovereigns sometimes excusably default, they never repudiate their debts. The reputational equilibrium can involve efficient risk shifting and efficient investment or it can involve a binding lending ceiling that limits risk shifting and can also restrict investment. The factors that tend to produce a binding lending ceiling include a high time discount rate for the sovereign, low-risk aversion forthe sovereign, and a low net return from the sovereign's investments.

Seigniorage, Inflation, and Reputation

This paper derives a reputational equilibrum for inflation in a model in which the government obtains valuable seigniorage by issuing fiat money in echange for real resources. One insightful result is that , with contemporaneous perceptionof actual government behavior and immediate adjustment of real cash balences to new information , the Friedman elasticity solution for maximal seigniorage is the reputatoinal equilibrium. More generally , the analysis shows that the objective of maximal seigniorage produces an equilibrium inflation rate equal either to a generalization of the Friedman elasticity solution or to the rate at which the government discounts future seigniorage adjusted for the growth rate, whichever is larger. Thus, the model formalizes the conjecture that epizodes of inflation rates in excess of the Friedman solution are attributable to high discounts rates for future seigniorage. Adding aversion to high expected inflation to the model, this analysis also rationalizes the observation that inflation rates are usually less than Friedman's elasticity solution.

Polynomial Response Surface Approximations for the Multidisciplinary Design Optimization of a High Speed Civil Transport

Surrogate functions have become an important tool in multidisciplinary design optimization to deal with noisy functions, high computational cost, and the practical difficulty of integrating legacy disciplinary computer codes. A combination of mathematical, statistical, and engineering techniques, well known in other contexts, have made polynomial surrogate functions viable for MDO. Despite the obvious limitations imposed by sparse high fidelity data in high dimensions and the locality of low order polynomial approximations, the success of the panoply of techniques based on polynomial response surface approximations for MDO shows that the implementation details are more important than the underlying approximation method (polynomial, spline, DACE, kernel regression, etc.). This paper surveys some of the ancillary techniques—statistics, global search, parallel computing, variable complexity modeling—that augment the construction and use of polynomial surrogates