p-Brane cosmology and phases of Brans-Dicke theory with matter

We study the effect of the solitonic degrees of freedom in string cosmology following the line of Rama. The gas of solitonic p-brane is treated as a perfect fluid in a Brans-Dicke type theory. In this paper, we find exact cosmological solutions for any Brans-Dicke parameter $\omega$ and for general parameter $\gamma$ of equation of state and classify the cosmology of the solutions on a parameter space of $\gamma$ and $\omega$.Comment: 26 pages, 5 figures, Contents and references added; published in Phys. Rev. D57(1998) 462

Singularity Free (Homogeneous Isotropic) Universe in Graviton-Dilaton Models

We present a class of graviton-dilaton models in which a homogeneous isotropic universe, such as our observed one, evolves with no singularity at any time. Such models may stand on their own as interesting models for singularity free cosmology, and may be studied further accordingly. They may also arise from string theory. We discuss critically a few such possibilities.Comment: 11 pages. Latex file. Revised in response to referees' Comments. Results remain same. To appear in Phys. Rev. Let

An Experimental Investigation on Trench Isolation Techniques for Vibration Control

One of the methods of controlling vibration amplitudes at source is by adopting active isolation techniques. Trench barriers are identified as methods of isolation. This paper deals with series experimental investigation carried out on block vibration tests with active isolation trench barriers. The parameters like depth of embedment, dimensions of trench, fill material in trench etc., are studied by carrying out the block vibration test in field. The results are analysed to identify the influence of those parameters

Generalization of Linearized Gouy-Chapman-Stern Model of Electric Double Layer for Nanostructured and Porous Electrodes: Deterministic and Stochastic Morphology

We generalize linearized Gouy-Chapman-Stern theory of electric double layer for nanostructured and morphologically disordered electrodes. Equation for capacitance is obtained using linear Gouy-Chapman (GC) or Debye-$\rm{\ddot{u}}$ckel equation for potential near complex electrode/electrolyte interface. The effect of surface morphology of an electrode on electric double layer (EDL) is obtained using "multiple scattering formalism" in surface curvature. The result for capacitance is expressed in terms of the ratio of Gouy screening length and the local principal radii of curvature of surface. We also include a contribution of compact layer, which is significant in overall prediction of capacitance. Our general results are analyzed in details for two special morphologies of electrodes, i.e. "nanoporous membrane" and "forest of nanopillars". Variations of local shapes and global size variations due to residual randomness in morphology are accounted as curvature fluctuations over a reference shape element. Particularly, the theory shows that the presence of geometrical fluctuations in porous systems causes enhanced dependence of capacitance on mean pore sizes and suppresses the magnitude of capacitance. Theory emphasizes a strong influence of overall morphology and its disorder on capacitance. Finally, our predictions are in reasonable agreement with recent experimental measurements on supercapacitive mesoporous systems

Implementasi Metode Paprika Dalam Pengembangan Aplikasi Ranking Untuk Seleksi Jabatan Dengan Multi Kriteria (Studi Kasus: PT. ABC)

Sumber Daya Manusia (SDM) merupakan salah satu aset yang memegang peranan penting dalam pemerintah, swasta, dan juga lembaga pendidikan yang perlu dikelola dengan baik. Salah satu cara untuk mengelola SDM tersebut adalah dengan melakukan seleksi jabatan yang tepat berdasar kriteria-kriteria yang dibutuhkan. Seleksi ini bertujuan untuk meranking dan menyeleksi karyawan yang memiliki kemampuan yang sesuai dengan jabatannya. Pada Perusahaan studi kasus terkait, seleksi jabatan masih dilakukan dengan cara manual dan belum ada perankingan dari karyawan yang diseleksi. Kondisi tersebut menyebabkan seleksi jabatan membutuhkan waktu yang lama. Tujuan penelitian ini adalah membuat suatu aplikasi untuk seleksi jabatan berupa perankingan. Pembuatan sistem ini berdasar pada multi kriteria yang telah ditetapkan oleh Perusahaan pada studi kasus terkait. Multi kriteria tersebut dimodelkan berdasar pada metode Potentially All Pairwise RanKings of all possible Alternatives (PAPRIKA), yang merupakan salah satumetode dalam sistem pendukung keputusan yang melibatkan multi kriteria. Dalam penerapannya, metode ini membandingkan semua kemungkinan pasangan yang terjadi pada kriteria-kriteria yang digunakan pada studi kasus terkait, lalu dibutuhkan keputusan dari pemegang keputusan untuk menentukan kriteria mana yang lebih diutamakan dibandingkan dengan kriteria lainnya. Berdasar pada keputusan tersebut, metode PAPRIKA diterapkan dan dimodelkan kedalam permasalahan yang ada. Penerapan tersebut menghasilkan perankingan dari seleksi karyawan yang dilakukan. Hasil dari penerapan metode ini adalah berupa aplikasi untuk melakukan ranking dalam seleksi jabatan berbasis web yang diharapkan dapat mempermudah pihak manajemen Perusahaan untuk mengambil keputusan dalam menentukan karyawan yang memiliki kompetensi yang sesuai dan tepat pada jabatan tertentu

The cosmology with the Dp-brane gas

We study the effect of the Dp-brane gas in string cosmology. When one kind of Dp-brane gas dominates, we find that the cosmology is equivalent to that of the Brans-Dicke theory with the perfect fluid type matter. We obtain $\gamma$, the equation of state parameter, in terms of p and the space-time dimension.Comment: 12 pages, 3 figure

Evolution of Topological Defects During Inflation

Topological defects can be formed during inflation by phase transitions as well as by quantum nucleation. We study the effect of the expansion of the Universe on the internal structure of the defects. We look for stationary solutions to the field equations, i.e. solutions that depend only on the proper distance from the defect core. In the case of very thin defects, whose core dimensions are much smaller than the de Sitter horizon, we find that the solutions are well approximated by the flat space solutions. However, as the flat space thickness parameter $\delta_0$ increases we notice a deviation from this, an effect that becomes dramatic as $\delta_0$ approaches $(H)^{-1}/{\sqrt 2}$. Beyond this critical value we find no stationary solutions to the field equations. We conclude that only defects that have flat space thicknesses less than the critical value survive, while thicker defects are smeared out by the expansion.Comment: 14 page

Combinatorial Identities and Quantum State Densities of Supersymmetric Sigma Models on N-Folds

There is a remarkable connection between the number of quantum states of conformal theories and the sequence of dimensions of Lie algebras. In this paper, we explore this connection by computing the asymptotic expansion of the elliptic genus and the microscopic entropy of black holes associated with (supersymmetric) sigma models. The new features of these results are the appearance of correct prefactors in the state density expansion and in the coefficient of the logarithmic correction to the entropy.Comment: 8 pages, no figures. To appear in the European Physical Journal