Development of a Multi-Projection Approach for Global Web Map Visualization

The popularity of web mapping services such as Google and Bing Maps is growing. However, professional users experience several limitations while using these on-line mapping services. The first problem is the limited global coverage. The coverage ends at latitude of 85° north and south. The second problem is the systematic distortion that increases with latitude. For example, in Google Maps Greenland appears to be larger than South America, whereas in reality Greenland is 8 times smaller. The third problem is the lack of mathematical rigour for the cartographic projections because the Earth is treated as a sphere instead of an ellipsoid. Thus, a better web mapping system is needed for professional users and users interested in polar regions. This thesis presents a multi-projection approach for global web map visualization. The multi-projection approach minimizes the cartographic distortions by using different projections across the globe and for ranges of mapping detail levels

The formation of price expectations: a case study of the soybean market

Stochastic dynamic optimization is performed for a representative consumer and producer in the soybean market. Each is assumed to maximize the expected value of the infinite sum of the present value of his (her) income stream. Optimum rules for each side are solved as a function of, among other things, expected future prices. Three price expectations are applied--rational, adaptive, and cash-futures. Estimation, based upon the aggregate U.S. soybean market. Time series analysis and Granger-causality test are utilized at the first stage of estimation in order to obtain information which help to forecast prices. The derived decision rules under rational expectations hypothesis are nonlinear function of parameters appearing in agents\u27 objective functions. All variables that are in the information set which help to predict future values of prices are in the decision rules. The response functions of all decision rules under rational expectations hypothesis depend upon the values of all structural parameters. Dynamic simulation of Quasi-Rational expectations model is performed with relatively good results. The estimation under the other two hypotheses--adaptive and cash-futures price expectations--are relatively inferior

Voyager radio occultation by the Uranian rings: Structure, dynamics, and particle sizes

Diffraction of Voyager 2's 3.6 and 13 cm wavelength microwaves by the Uranian rings is removed through an inverse Fresnel transform filtering procedure that accommodates the significant eccentricity of the rings. Resulting 50 m resolution profiles at two observation longitudes: (1) reveal remarkably detailed and longitudinally varying structure, (2) provide eccentricity gradient profiles of Rings alpha, beta, and epsilon which bring into question current theoretical models for observed rigid precession, and (3) suggest that two possible unseen satellites may confine some of the very sharp edges observed via resonant interactions

Bathrooms, bubbles and systems : archigram and the landscapes of transience

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.Includes bibliographical references (leaves 168-175).The dissertation studies the Archigram, the primary avant-garde architectural publication in Britain from 1961 to 1970, and the related avant-garde practices that engendered the high-tech movement. Drawing on the histories of technology, architecture and popular culture, the study explores the roots of architecture's foray into the realm of electronic information. By challenging the machine-based model of technology that had defined modernist architectural theory and production, my thesis unfolds, the publishers of the Archigram struggled to reconcile architectural form with emerging technologies and to represent visually the dissolution of the artifact into a landscape of complex and indeterminate systems. This attempt to conceive an essentially material object, such as a house, in a world viewed as a series of impulses was among the earliest architectural explorations of the dilemmas introduced by electronic culture. Using the concept of mobility and flux as a unifying thread, the dissertation examines the strategy for developing an architecture based in the practice of representation and of dissemination. The desire to set structures in motion by liberating them from the anchor of urban infrastructures required a reconsideration of the architectural object. For architecture to fully abandon its traditional role as environmental hardware, the conflict between the processes of indeterminacy and the dependence of those processes on a closed system would have to be overcome.(cont.) This tension between the physical and the dematerialized led from megastructural networks to self-contained skins, and finally to the disintegration of architectural objects into a technologically driven version of the Picturesque. In the ultimate merging of the environmental domain with that of information, architecture would become its absence, marked in the landscape only as the residue of a nomadic culture of information.by Hadas A. Steiner.Ph.D

Intrinsic properties of Hellenic “Marls”

Post-alpine deposits cover substantial areas of Hellas. The fine grained facies of these deposits, comprise a wide range of over consolidated materials of varying grading and mineralogy. On average, however, these deposits cover different depositional environments and may be classed as silty clays and clayey silts of low to intermediate plasticity containing calcite in their mineralogical suite. Such deposits have been collectively known to practising engineers as marls. A concerted effort to collect field and laboratory data and interpret the behaviour of these materials was recently launched in view of the involvement of the aforesaid mentioned deposits in a series of geotechnical problems. This thesis aspires to contribute to this knowledge and provide a framework on which the field performance of such materials may be interpreted. To that end, disturbed and high quality undisturbed samples from the geologically dissimilar areas of Korinthos, Preveza-Igoumenitsa road axis and Amalias- Goumeron were obtained and tested in order to ascertain their physical characteristics and mineralogical composition. Further, engineering properties which are independent of stress history, i.e. intrinsic, of the materials sampled, were determined. These were the residual strength as determined by ring shearing and the compressibility of reconstituted samples. The performance of the samples was assessed in terms of grain size distribution and mineralogy. The results show that any attempt to explain or predict intrinsic properties of Hellenic fine grained calcareous sediments without taking simultaneous account of gradation and mineralogy is incomplete and therefore inaccurate

The virtual erector set

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1990.Includes bibliographical references (leaves 95-96).by Peter Schröder.M.S

Estimators for the errors-in-variables model

Estimators of the parameters of the multivariate linear errors-in-variables model and the nonlinear errors-in-variables model are investigated. The multivariate linear errors-in-variables model is defined by; Y(,t) = (beta)(,0) + x(,t)(beta) + e(,t),; X(,t) = x(,t) + u(,t), t = 1,2,...,n,;where Y(,t) and X(,t) are observable random row vectors of dimensions r and k, respectively, e(,t) and u(,t) are unobservable error vectors, x(,t) is an unobservable random or fixed vector, (beta)(,0) is a 1 x r vector of parameters, (beta) is a k x r matrix of parameters, and (epsilon)(,t) = (e(,t), u(,t)) are independently and identically distributed with mean zero and covariance matrix (SIGMA)(,(epsilon)(epsilon)). It is assumed that an independent estimator S(,(epsilon)(epsilon)) of (SIGMA)(,(epsilon)(epsilon)) is available;Under the assumption that the (epsilon)(,t) are normally distributed and that S(,(epsilon)(epsilon)) is a multiple of a Wishart matrix, the maximum likelihood estimators are obtained for the model with fixed x(,t) and the model with normally distributed x(,t). The asymptotic properties of the estimators are derived under minimal assumptions;The nonlinear errors-in-variables model is defined by; Y(,nt) = f(x(,t); (beta)) + e(,nt),; X(,nt) = x(,t) + u(,nt), t = 1,2,...,b(,n),;where x(,t) is an unobservable fixed row vector of dimension q, (Y(,nt), X(,nt)) are observed in the n-th experiment, (beta) is a k x 1 vector of parameters, and (e(,nt), u(,nt)) are independently distributed with mean zero and covariance matrix (SIGMA)(,n). It is assumed that n = a(,n)b(,n) for all n and that;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);For the nonlinear model with known (SIGMA)(,n), the asymptotic bias of the normal maximum likelihood estimator is obtained. A class of estimators adjusted for the nonlinearity bias is given. Three estimators in the class are discussed and compared in a Monte Carlo study;The instrumental variable estimator (\u27)(beta)(,n) of (beta) is defined for the nonlinear model with unknown (SIGMA)(,n) when additional information is provided by an observable vector W(,nt). The asymptotic properties of (\u27)(beta)(,n) and of estimators of (SIGMA)(,n) and x(,t) based on (\u27)(beta)(,n) are derived. A modified instrumental variable estimator (\u27)(beta)(,n) of (beta) is constructed using (\u27)(beta)(,n) as a preliminary estimator. The estimator (\u27)(beta)(,n) is shown to be asymptotically more efficient than (\u27)(beta)(,n)

Spatial Displays and Spatial Instruments

The conference proceedings topics are divided into two main areas: (1) issues of spatial and picture perception raised by graphical electronic displays of spatial information; and (2) design questions raised by the practical experience of designers actually defining new spatial instruments for use in new aircraft and spacecraft. Each topic is considered from both a theoretical and an applied direction. Emphasis is placed on discussion of phenomena and determination of design principles

Numerical Simulation of Thermo-Chemo-Hygro-Mechanical Alkali-Silica Reaction Model in Concrete at the Mesoscale and Macroscale

Alkali-silica reaction causes major problems in concrete structures due to the rapidity of its deformation which leads to the serviceability limit of the structure being reached well before its time. Factors that affect ASR vary greatly, including alkali and silica content, relative humidity, temperature and porosity of the cementitious matrix,all these making it a very complex phenomenon to consider explicitly. With this in mind, the finite element technique was used to build models and generate expansive pressures and damage propagation due to ASR under the influence of thermo-hygrochemoelastic loading. Since ASR initializes in the mesoscopic regions of the concrete, the accumulative effects of its expansion escalates onto the macroscale level with the development of web cracking on the concrete surface, hence solution of the damage model as well as simulation of the ASR phenomenon at both the macroscale and mesoscale levels have been performed. The macroscale model realizes the effects of ASR expansion as a whole and shows how it develops under the influence of moisture, thermal and mechanical loading. Results of the macroscale modeling are smeared throughout the structure and are sufficient to show how damage due to ASR expansion orientates. As opposed to the mesoscale model, the heterogeneity of the model shows us how difference in material properties between aggregates and the cementitious matrix facilitates ASR expansion. With both these models, the ASR phenomenon under influence of thermo-chemo-hygro-mechanical loading can be better understood