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731.
Multi-frequency excitation of magnetorheological elastomer-based sandwich beam with conductive skins
The present work deals with the dynamic stability of a symmetric sandwich beam with magnetorheological elastomer (MRE) embedded viscoelastic core and conductive skins subjected to time varying axial force and magnetic field. The conductive skins induce magnetic loads and moments under the application of magnetic field during vibration. The MRE part works in shear mode and hence the dynamic properties of the sandwich beam can be controlled by magnetic fields due to the field dependent shear modulus of MRE material. Considering the core to be incompressible in transverse direction, classical sandwich beam theory has been used along with extended Hamilton's principle and Galarkin's method to derive the governing equation of motion. The resulting equation reduces to that of a multi-frequency parametrically excited system. Second order method of multiple scales has been used to study the stability of the system for simply supported and clamped free sandwich beams. Here the experimentally obtained properties of magnetorheological elastomers based on natural rubber have been considered in the numerical simulation. The results suggest that the stability of the MRE embedded sandwich beam can be improved by using magnetic field. 相似文献
732.
Clover detector has been used as a Compton polarimeter to measure the linear polarization of γ-rays produced in heavy ion
fusion reaction. The polarization sensitivity of the clover detector has been measured over γ-ray energies ranging from 386
to 1368 ke V. The E1 multipolarity of the 1117 keV transition in 99Rh has been established using this polarimeter. This has resulted in the assignment of negative parity to the band head at
3710 keV in 99Rh. 相似文献
733.
Gnana Sutha Siluvai Babu Varghese Narasimha N. Murthy 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o380-o382
In the title salt, 1,3‐bis{[2‐(2‐pyridinio)ethyl][2‐(2‐pyridyl)ethyl]amino}benzene diperchlorate dihydrate, C34H38N62+·2ClO4−·2H2O, the cation contains two ethylpyridyl and two ethylpyridinium pendant pairs anchored to the two N atoms of 1,3‐phenylenediamine. The pyridyl and pyridinium N atoms are flanked by a molecule of water through strong hydrogen‐bonding interactions [N—H⋯O = 2.762 (6) and 2.758 (6) Å, and O—H⋯N = 2.834 (6) and 2.839 (6) Å]. The water molecules have weak hydrogen‐bonding interactions with the perchlorate anions as well. One of the perchlorate anions is severely disordered. 相似文献
734.
We consider the numerical solution by finite difference methods of the heat equation in one space dimension, with a nonlocal integral boundary condition, resulting from the truncation to a finite interval of the problem on a semi-infinite interval. We first analyze the forward Euler method, and then the $θ$-method for $0 < θ ≤ 1$, in both cases in maximum-norm, showing $O(h^2 + k)$ error bounds, where $h$ is the mesh-width and $k$ the time step. We then give an alternative analysis for the case $θ = 1/2$, the Crank-Nicolson method, using energy arguments, yielding a $O(h^2$ + $k^{3/2}$) error bound. Special attention is given the approximation of the boundary integral operator. Our results are illustrated by numerical examples. 相似文献
735.
Sureshkumar D Koutha SM Chandrasekaran S 《Journal of the American Chemical Society》2005,127(37):12760-12761
Benzyltriethylammonium tetrathiomolybdate, [BnEt3N]2MoS4, has been used successfully to effect ring opening of aziridines in a regiospecific and stereospecific manner under mild reaction conditions without the use of Lewis acid catalyst. Utility of this reagent in tandem and multistep processes in a one-pot operation for the synthesis of various novel sulfur heterocycles in very good yield is also reported. 相似文献
736.
Srinivas O Radhika S Bandaru NM Nadimpalli SK Jayaraman N 《Organic & biomolecular chemistry》2005,3(23):4252-4257
The synthesis of multivalent dendritic cluster glycosides of mannopyranosyl-6-phosphate is presented. Poly(amido amine)-based dendrimers of 0.5-3.5 generations, containing carboxylic acid peripheral functionalities, were utilized so as to install 4, 8, 16 and 32 mannopyranosyl-6-phosphate residues at the peripheries of the dendrimers. Amide bond formation between an amine-tethered mannopyranosyl-6-phosphate monomer unit and carboxylic acid-functionalized dendrimers was conducted to synthesize the dendritic cluster glycosides. The constitutions of the Man-6-P-containing dendrimers were assessed by 1H, 13C and 31P NMR spectroscopies and the sugar content analysis by a resorcinol assay. Preliminary biological studies with few newly synthesized Man-6-P-containing dendrimers showed that these compounds could bind the purified goat liver mannose 6-phosphate receptor (MPR 300) protein. 相似文献
737.
Using a fermionic renormalization group approach, we analyze a model where the electrons diffusing on a quantum dot interact via Fermi-liquid interactions. Describing the single-particle states by random matrix theory, we find that interactions can induce phase transitions (or crossovers for finite systems) to regimes where fluctuations and collective effects dominate at low energies. Implications for experiments and numerical work on quantum dots are discussed. 相似文献
738.
Gribelyuk MA McCartney MR Li J Murthy CS Ronsheim P Doris B McMurray JS Hegde S Smith DJ 《Physical review letters》2002,89(2):025502
Quantitative two-dimensional maps of electrostatic potential in device structures are obtained using off-axis electron holography with a spatial resolution of 6 nm and a sensitivity of 0.17 V. Estimates of junction depth and variation in electrostatic potential obtained by electron holography, process simulation, and secondary ion mass spectroscopy show close agreement. Measurement artifacts due to sample charging and surface "dead layers" do not need to be considered provided that proper care is taken with sample preparation. The results demonstrate that electron holography could become an effective method for quantitative 2D analysis of dopant diffusion in deep-submicron devices. 相似文献
739.
In this note we show that the results of Nakagawa and Osaki are optimal over both deterministic and random repair limit policies. 相似文献
740.
Changes in the lamellar and crystalline structures were followed as a function of applied stress to understand the influence of the interactions between the crystalline and amorphous domains on the fiber properties. We observed a reversible transformation from a structure giving a four‐point small‐angle pattern to a structure giving a two‐point pattern; these structures corresponded to the lamellae with oblique and normal lamellar surfaces, respectively. The characteristics of these two structures such as the stack diameter, stack height, and tilt angle were different and were determined by the processing conditions and did not change when the fiber was elastically deformed. The structure giving a two‐point pattern was probably the load‐carrying lamellar entity in these fibers. The diameter of the lamellar stacks, tilt angle of the lamellae, and the strain in the lamellar spacing appeared to have the most influence on properties such as tenacity and dimensional stability. The long‐spacing strain, which is about the same as the fiber strain, determined the modulus at low elongation as well as ultimate elongation. These indicate that the lamellar stacks have at least as much influence as the interfibrillar chains on fiber properties. Structural features that determine the performance in semicrystalline polymers were investigated by analyzing four generations of polyethylene terephthalate fibers. Some of the fiber properties correlate with changes in the crystalline domains such as the crystalline orientation, size, and unit cell dimensions. Fibers in which the crystalline strain was large because of their strong linkages to the amorphous chains, and better load transfer, had the highest modulus and lowest ultimate elongation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1538–1553, 2003 相似文献