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991.
Effect of irregularity and heterogeneity on the stresses produced due to a normal moving load on a rough monoclinic half-space 总被引:2,自引:0,他引:2
The present study aims to study the normal and shear stresses produced in a rough irregular heterogeneous monoclinic half-space due to a normal moving load. Closed form expressions of normal and shear stresses have been obtained. It is observed that both normal stress and shear stress are affected not only by depth, the frictional coefficient on a rough surface, and the maximum depth of irregularity but also by the heterogeneity and types of irregularity in the medium. The comparative study has been made to analyze the effect of different types of irregularity on both the stresses. There is a significant effect of depth, frictional coefficient, heterogeneity, maximum depth of irregularity and irregularity factor on the normal and shear stresses in both heterogeneous monoclinic and heterogeneous isotropic medium. A comparison is made to study the effects of the said parameters on the normal and shear stress produced in both heterogeneous medium. These effects are highlighted and depicted by means of graphs. As a special case of the problem, the stress produced due to normal moving load in an isotropic half-space with and without heterogeneity, irregularity has been discussed. 相似文献
992.
Antonio Pasqua Surajit Chattopadhyay Iuliia Khomenko 《International Journal of Theoretical Physics》2013,52(7):2496-2507
The new agegraphic Dark Energy (NADE) model (based on generalized uncertainty principle) interacting with Dark Matter (DM) is considered in this study via power-law form of the scale factor a(t). The equation of state (EoS) parameter ω G is observed to have a phantom-like behaviour. The stability of this model is investigated through the squared speed of sound $v_{s}^{2}$ . It is found that $v_{s}^{2}$ always stays at negative level. This indicates instability of the considered model. Moreover, validity of the generalized second law of thermodynamics has been investigated assuming that the apparent horizon is the enveloping horizon. It has been observed that the generalized second law is valid throughout the evolution of the universe. 相似文献
993.
K. Biswas G. Phanikumar D. Holland-Moritz Dieter M. Herlach K. Chattopadhyay 《哲学杂志》2013,93(25):3817-3837
The electromagnetic levitation technique has been used to systematically study microstructure evolution and growth rate as a function of undercooling in concentrated Fe–18 at% Ge alloy. The samples are undercooled to a maximum of 240?K. Growth-rate analysis and transmission electron microscopy reveal that, beyond an undercooling of 120?K, the primary phase to solidify is disordered. Microstructural investigations show a decrease in grain size with increasing undercooling. Orientation-imaging microscopy using electron back-scattered diffraction (EBSD) and microhardness measurements have been used to show that recovery and recrystallization play a significant role in the evolution of final microstructure. Microstructural evolution has also been discussed in light of current models of dendrite growth and grain refinement. 相似文献
994.
Sourav Rana Sabyasachi Bhattacharya Joydeep Pal Gaston M. N’Guérékata Joydev Chattopadhyay 《Physica A》2013
The paradox of enrichment (PoE) proposed by Rosenzweig [M. Rosenzweig, The paradox of enrichment, Science 171 (1971) 385–387] is still a fundamental problem in ecology. Most of the solutions have been proposed at an individual species level of organization and solutions at community level are lacking. Knowledge of how learning and memory modify behavioral responses to species is a key factor in making a crucial link between species and community levels. PoE resolution via these two organizational levels can be interpreted as a microscopic- and macroscopic-level solution. Fractional derivatives provide an excellent tool for describing this memory and the hereditary properties of various materials and processes. The derivatives can be physically interpreted via two time scales that are considered simultaneously: the ideal, equably flowing homogeneous local time, and the cosmic (inhomogeneous) non-local time. Several mechanisms and theories have been proposed to resolve the PoE problem, but a universally accepted theory is still lacking because most studies have focused on local effects and ignored non-local effects, which capture memory. Here we formulate the fractional counterpart of the Rosenzweig model and analyze the stability behavior of a system. We conclude that there is a threshold for the memory effect parameter beyond which the Rosenzweig model is stable and may be used as a potential agent to resolve PoE from a new perspective via fractional differential equations. 相似文献
995.
Olga Ratsimor Dipanjan Chakraborty Anupam Joshi Timothy Finin Yelena Yesha 《Mobile Networks and Applications》2004,9(6):679-692
Directory based service discovery mechanisms are unsuitable for ad-hoc m-commerce environments. Working towards finding an alternate mechanism, we developed Allia: a peer-to-peer caching based and policy-driven agent-service discovery framework that facilitates cross-platform service discovery in ad-hoc environments. Our approach achieves a high degree of flexibility in adapting itself to changes in ad-hoc environments and is devoid of common problems associated with structured compound formation in mobile commerce environments. Device capabilities and limitations, user preferences regarding device usage, application specifics with respect to mobile commerce are factors that our framework adapts to. We have described our initial implementation of Allia over ThinkPads and iPAQs by extending the LEAP Agent Platform and using Bluetooth as the underlying network protocol. In addition, we evaluated Allia's performance by running simulations of our protocol in Glomosim simulator. We also compared our framework against a structured compound-based architecture. 相似文献
996.
Naba K. Mondal Saurabh D. Rindani Kaustubh Agashe Pankaj Agrawal B. Ananthanarayan Ketevi Assamagan Alfred Bartl Subhendu Chakrabarti Utpal Chattopadhyay Debajyoti Choudhury Eung-Jin Chun Prasanta K. Das Siba P. Das Amitava Datta Sukanta Dutta Jeff Forshaw Thomas Gajdosik Dilip K. Ghosh Rohini M. Godbole Monoranjan Guchait Partha Konar Sabine Kraml Manas Maity Kajari Mazumdar Naba K. Mondai Biswarup Mukhopadhyaya Meenakshi Narain Santosh K. Rai Sreerup Raychaudhuri Saurabh D. Rindani D. P. Roy Seema Sharma Ritesh K. Singh Rishikesh Vaidya 《Pramana》2004,63(6):1331-1353
This is a summary of the projects undertaken by the working group I on high energy and collider physics. 相似文献
997.
Zhizhong Liu Sruti Chattopadhyay Montgomery T. Shaw Benjamin S. Hsiao 《Journal of Polymer Science.Polymer Physics》2004,42(8):1496-1505
Nanostructured squalane solutions (5–20 wt %) of a diblock copolymer, poly(styrene‐b‐hydrogenated isoprene), were prepared by a cosolvent‐casting method. The as‐cast solutions behaved as viscous liquids with terminal flow behavior at room temperature. Upon heating, the solutions gelled, and they did not return to their starting liquidlike state upon cooling. Small‐angle X‐ray scattering (SAXS) revealed a random array of spherical micelles in the as‐cast solutions, which were hypothesized to be in a nonequilibrium state. This abnormal solidification with increasing temperature was correlated with the formation of body‐centered‐cubic (BCC) structures. Isothermal SAXS and rheology measurements also indicated that the rate of formation of BCC structures in the as‐cast solutions increased with temperature. A diffusion‐controlled nucleation‐and‐growth mechanism was proposed for the ordering process in the as‐cast polystyrene‐b‐hydrogenated polyisoprene/squalane solutions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1496–1505, 2004 相似文献
998.
Sumita Naskar Subhendu Naskar Mike G.B. Drew Serge I. Gorelsky Benedikt Lassalle-Kaiser Ally Aukauloo Dipankar Mishra Shyamal Kumar Chattopadhyay 《Polyhedron》2009,28(18):4101-4109
Six Ru(II) complexes of formula [Ru(L)2(PPh3)2] have been prepared where LH = 4-(aryl)thiosemicarbazones of thiophen-2-carbaldehyde. X-ray crystal structures of five of the complexes are reported. In all the complexes ruthenium is six coordinate with a distorted octahedral cis-P2, cis-N2, trans-S2 donor environment, and each of the two thiosemicarbazone ligands are coordinated in a bidentate fashion forming a four membered chelate ring. The complexes undergo a one-electron oxidation at ~0.5 V vs. Ag/AgCl. The EPR spectrum of the electrochemically oxidized solution at 100 K shows a rhombic signal, with transitions at g1 = 2.27, g2 = 2.00 and g3 = 1.80. DFT calculations on one of the complexes suggest that there is 35% ruthenium and 17% sulfur orbital contribution to the HOMO. These results suggest that the assignment of metal atom oxidation states in these compounds is not unambiguous. 相似文献
999.
Syam P. Nandi P.K. Chattopadhyay A.K. 《Industrial Electronics, IEEE Transactions on》1998,45(6):950-953
A novel method of online detection and frequency-selective feedback to suppress the subharmonic frequency components in a naturally commutated cycloconverter is described. Simulation results show a significant reduction of these components over a wide range of frequency and load power factor angle. The scheme also includes a loop for compensating the voltage distortion due to discontinuous current in a practical noncirculating-type cycloconverter 相似文献
1000.
Goutam Chattopadhyay Frank Maiwald Erich Schlecht Robert J. Dengler John C. Pearson Imran Mehdi 《Journal of Infrared, Millimeter and Terahertz Waves》2003,24(9):1485-1498
Heterodyne instruments at millimeter and submillimeter wavelengths often use wideband fixed-tuned frequency multipliers, in conjunction with broadband power amplifiers driven by frequency synthesizers, as the local oscillator (LO) source. At these frequencies the multipliers use Gallium Arsenide (GaAs) based Schottky varactor diodes as the nonlinear element, and like most other harmonic generators are susceptible to spurious signal interference. The state-of-the-art LO sources at these wavelengths use high power MMIC amplifiers at the initial stages, and are used to drive the subsequent multiplier stages to have enough LO power to pump the mixers. Because of the high input power environment and the presence of noise in the system, the multipliers become vulnerable to spurious signal interference. As the spurious signals propagate through the receiver system, they generate inter-modulation products which might fall in the passband of the heterodyne instrument and seriously degrade its performance. In this paper spurious signal response of solid-state frequency multipliers at millimeter and submillimeter wavelengths is investigated. Results of numerical harmonic balance simulations and laboratory experiments, which were found to show good agreement, are presented here. 相似文献