6,183 research outputs found
Timber roof structure for outdoor auditorium in Parque Paraiso, San Blas (Madrid)
Get PDFp. 468-475A timber shell structure is designed to provide covering for an outdoor auditorium in
Madrid (Spain). The covering comprises five independent overlapped marquees with
similar shape but diverse dimensions. The surface geometry of each marquee is defined by a hyperbolic paraboloid, with its boundaries delimited by elliptical curves in horizontal
projection. Structural section for the timber shell is a composite section with several
staggered layers of straight sawn timber planks, arranged in two orthogonal directions
following the straight skew lines of the hyperbolic paraboloid. Over them two continuous
top layers are arranged which provides bracing for the structure and support for the
waterproofing material. Each layer is laid over the previous one, bolted and glued with
polyurethane adhesive. Special characteristics of the design analysis and detailed erection process are described. The designed solution provides lightweight roofing with a powerful and original image, short construction time and reasonable budget.Anton, A.; Meijide, AG.; Corbal, JJ. (2009). Timber roof structure for outdoor auditorium in Parque Paraiso, San Blas (Madrid). Editorial Universitat Politècnica de València. https://riunet.upv.es/handle/10251/653
Iceberg Scour and Shell Damage in the Antarctic Bivalve Laternula elliptica
Get PDFWe document differences in shell damage and shell thickness in a bivalve mollusc (Laternula elliptica) from seven sites around Antarctica with differing exposures to ice movement. These range from 60% of the sea bed impacted by ice per year (Hangar Cove, Antarctic Peninsula) to those protected by virtually permanent sea ice cover (McMurdo Sound). Patterns of shell damage consistent with blunt force trauma were observed in populations where ice scour frequently occurs; damage repair frequencies and the thickness of shells correlated positively with the frequency of iceberg scour at the different sites with the highest repair rates and thicker shells at Hangar Cove (74.2% of animals damaged) compared to the other less impacted sites (less than 10% at McMurdo Sound). Genetic analysis of population structure using Amplified Fragment Length Polymorphisms (AFLPs) revealed no genetic differences between the two sites showing the greatest difference in shell morphology and repair rates. Taken together, our results suggest that L. elliptica exhibits considerable phenotypic plasticity in response to geographic variation in physical disturbance
Particle-spring method for form finding grid shell structures consisting of flexible members
No full textIn this paper a general design method is described that can significantly reduce the effort needed for form finding grid shells consisting of flexible members. This design method is based on particle-spring models for simulating the behaviour of a grid shell during construction. Hereby, the stress limitations that follow from the material properties are taken into account to modify the grid shell geometry with a minimal deviation from a pre-defined target shape. It is demonstrated how a simple design tool can generate the geometry, internal forces and the support reactions with satisfactory accuracy.Structural EngineeringCivil Engineering and Geoscience
The Economic Effects of Restrictions on Government Budget Deficits: Imperfect Privte Credit Markets
Get PDFWe consider a pure-exchange overlapping-generations model We consider a pure-exchange overlapping-generations model with many consumers per generation and many goods per period. As in Ghiglino and Shell (2000), there is a government that collects taxes, distributes transfers and faces budget deficit restrictions. We introduce, for realism and symmetry with the government, imperfection in the private credit markets. We find that with constraints on individual credit and anonymous (i.e., non-personalized) lump-sum taxes, strong (or 'global') irrelevance of the government budget deficit is not possible, and weak irrelevance can hold only in very special situations. With credit constraints and anonymous consumption taxes, weak irrelevance holds provided the number of tax instruments is sufficiently large and at least one consumer's credit constraint is not binding.
AN INTERVIEW WITH KARL SHELL
No full textKarl Shell is without a doubt one of the central players in the development of economic theory and macroeconomics in the latter part of the twentieth century. He has made important contributions on topics ranging from growth theory, to overlapping generations, to extrinsic uncertainty, to monetary economics, to market games, and to technological innovation. His collaborations with Dave Cass are legend, and include the seminal formulation of the concept of sunspot equilibria. His Notes on the Economics of Infinity, and his papers with Yves Balasko are overlapping-generations classics. Shell s many coauthors read like a Who s Who in economics, and include (in no particular order) Joe Stiglitz, Franklin Fisher, Miguel Sidrauski, Ned Phelps, Duncan Foley, Walt Heller, Albert Ando, Jim Peck, Rod Garratt, Aditya Goenka, Christian Ghiglino, and Todd Keister. This is also a club to which we are also proud to belong.Shell s research is first rate and highly innovative, but his full contribution to economic theory must also be judged by his long service as the editor of one of the profession s premier journals, the Journal of Economic Theory. As the founding editor of JET, Shell took a small upstart journal, originally envisioned as a niche outlet for papers on mathematical economics, and turned it into one of the best in the profession. JET has published papers that have had major impacts on the development of economic theory in all its various flavors.Because of Shell s long stewardship of JET, the story of his professional life which we hope we have captured in this interview is also a history of the evolution of economic theory over the past quarter century. We spoke with Karl in his office at Cornell University and over lunch at the faculty club in the Statler, and the interview tapes we made were very much a three-way conversation between Karl and the two of us. In editing the transcripts of these tapes for publication, we wished to keep the focus of the conversation on Shell, and have therefore adopted the same anonymous MD moniker we used in our interview of Dave Cass to mask the identity of the questioner. We hope you enjoy the conversation as much as we did.
Continuous representation for shell models of turbulence
No full textIn this work we construct and analyze continuous hydrodynamic models in one space dimension, which are induced by shell models of turbulence. After Fourier transformation, such continuous models split into an infinite number of uncoupled subsystems, which are all identical to the same shell model. The two shell models, which allow such a construction, are considered: the dyadic (Desnyansky--Novikov) model with the intershell ratio and the Sabra model of turbulence with . The continuous models allow understanding various properties of shell model solutions and provide their interpretation in physical space. We show that the asymptotic solutions of the dyadic model with Kolmogorov scaling correspond to the shocks (discontinuities) for the induced continuous solutions in physical space, and the finite-time blowup together with its viscous regularization follow the scenario similar to the Burgers equation. For the Sabra model, we provide the physical space representation for blowup solutions and intermittent turbulent dynamics
Reforming finance in transitional socialist economies : avoiding the path from shell money to shell games
Get PDFIn the late 1980s, transitional socialist economies (TSEs) in Central and Eastern Europe were only somewhat more sophisticated than shell money systems: savings books or currency had to be used for most transactions and there was no risk assessment, information monitoring and acquisition, or portfolio management. The TSEs have moved toward a two-tiered banking system but they lag in the development of competitive, market-based financial systems. In several TSEs the financial system seems to be part of a shell game to hide the losses of the real economy. The authors argue that rapid, successful economic reform requires putting the shell game to an end. They review several contentious issues of financial reform in the TSEs, especially issues involving macrofinance, corporate finance, the internal debt problems, and the need to build efficient banks. The authors contend that the banks should be"cleaned up"when they are privatized, to prevent the quick reemergence of debt problems. They believe that either of the proposed alternatives for shaping financial systems in the TSEs - very highly capitalized banking or narrow banking - would minimize the need for future support. Either alternative would reduce leverage in the TSEs and provide more financial stability. But taking concerns about moral hazard to an extreme - prohibiting debt finance - could starve new firms for credit and limit economic growth.Economic Theory&Research,Financial Crisis Management&Restructuring,Environmental Economics&Policies,Banks&Banking Reform,Financial Intermediation
A Unified Shell model for Buoyancy-Driven Turbulence
No full textWe construct a unified shell model for stably stratified and convective turbulence. Shell model simulation of stably stratified flow in turbulent regime exhibit Bolgiano-Obukhbov (BO) scaling in which the kinetic energy spectrum varies as . However, simulation of convective turbulence shows Kolmogorov's spectrum. These results are consistent with the direct numerical simulations of Kumar {\em et al.} [Phys. Rev. E {\bf 90}, 023016 (2014)]. We also observe a dual scaling ( and ) for a limited range of parameters in stably stratified flow
Effects of shell thickness on the thermal stability of Cu-Ag core-shell nanoparticles: A molecular dynamics study
No full textCu-Ag core-shell (CS) nanoparticle (NP) is considered as a cost-effective alternative material to nano silver sintering material in die attachment application. To further reduce the cost, the thickness of the Ag shell can be adjusted. Whereas the shell thickness will also affect the thermal stability of the Cu-Ag CSNPs. In this study, molecular dynamics simulation was applied to study the thickness effect on the thermal behavior of Cu-Ag CSNPs. The melting points of CSNPs and Pure NPs can be determined by the evolutions of Potential Energy (PE), and the Lindemann index (LI) of the system. The results indicated that the melting points of CS NPs were lower than monometallic NP and the melting point of CS NP is influenced by the size of the Cu core and the number of lattice mismatches. Moreover, the distribution of atoms’ LI showed that the premelting point is independent of shell thickness. However, the fraction of atoms that occurred premelting is increased with the decrease of the shell thickness. Otherwise, we also simulated the sintering process of double CS NPs with equal size.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
- …
