Scaling Relations for Gravitational Collapse in Two Dimensions

It is known that radial collapse around density peaks can explain the key features of evolution of correlation function in gravitational clustering in three dimensions. The same model also makes specific predictions for two dimensions. In this paper we test these predictions in two dimensions with the help of N-Body simulations. We find that there is no stable clustering in the extremely non-linear regime, but a nonlinear scaling relation does exist and can be used to relate the linear and the non-linear correlation function. In the intermediate regime, the simulations agree with the model.Comment: Revised version, To appear in Ap

Nonlinear density evolution from an improved spherical collapse model

We investigate the evolution of non-linear density perturbations by taking into account the effects of deviations from spherical symmetry of a system. Starting from the standard spherical top hat model in which these effects are ignored, we introduce a physically motivated closure condition which specifies the dependence of the additional terms on the density contrast, $\delta$. The modified equation can be used to model the behaviour of an overdense region over a sufficiently large range of $\delta$. The key new idea is a Taylor series expansion in ($1/\delta$) to model the non-linear epoch. We show that the modified equations quite generically lead to the formation of stable structures in which the gravitational collapse is halted at around the virial radius. The analysis also allows us to connect up the behaviour of individual overdense regions with the non-linear scaling relations satisfied by the two point correlation function.Comment: 11 pages, 6 figures. Final version, contains added discussion and modified figures to match the accepted versio

Aerospace components made by Polymer material

The aerospace and aviation industry have fasted growing industries on a global scale. Reliable aircraft demands many top rubber components. These rubber components must-have high performance and endurance properties, since they will be exposed to a range of extreme weather conditions, such as excessively hot or cold temperatures, and different types of oils and gases. Rubber products are becoming more famous because of their durability under extreme environmental conditions and cost-effectiveness. The rubber used for aircraft must be of high quality, and this factor is most important in the production of the necessary parts. To study the effect of all compounding ingredients while optimizing compound design and conforming to the various specification requirements and to study the effect of aging, generally, rubber is tested at three different stages viz. Unvulcanised rubber, vulcanized rubber, and finished product

Dickey-Lincoln School Lakes Project at Dickey, Maine : Final Environmental Statement, Volume 1-4

The proposed Dickey-Lincoln School Lakes Project in northern Maine is a multipurpose installation on the St.John River. The combination hydroelectric power and flood control project is located in Aroostook County, Maine, near the Canadian border. The two proposed earth fill dams located at Dickey are 10,200 feet in length with a maximum height of 335 feet. They would impound 7.7 million acre feet of water at a maximum pool elevation 910 feet mean sea level. A second earth filled dam located 11 miles downstream at Lincoln School would serve as a regulatory dam. It would be 2100 feet in lenqth, 90 feet above the existing streambed

Fish and Wildlife Mitigation Report : Dickey-Lincoln School Lakes Project, Maine

The Dickey Lincoln School Lakes Project is a proposed multipurpose project located on the upper reaches of the St. John River in Aroostook County, Maine. Development would consist of two dams with associated reservoirs and hydroelectric generating facilities, five dikes and transmission lines. A more detailed description of the proposed project and its associated impacts is contained within the Revised Draft Environmental Impact Statement for the proposed project

Spherical collapse with dark energy

I discuss the work of Maor and Lahav [1], in which the inclusion of dark energy into the spherical collapse formalism is reviewed. Adopting a phenomenological approach, I consider the consequences of - a) allowing the dark energy to cluster, and, b) including the dark energy in the virialization process. Both of these issues affect the final state of the system in a fundamental way. The results suggest a potentially differentiating signature between a true cosmological constant and a dynamic form of dark energy. This signature is unique in the sense that it does not depend on a measurement of the value of the equation of state of dark energy.Comment: To appear in the proceedings of the ``Peyresq Physics 10" Workshop, 19 - 24 June 2005, Peyresq, Franc