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721.
722.
723.
Thermoelastic interaction with energy dissipation in a transversely isotropic thin circular disc 总被引:1,自引:0,他引:1
The distribution of stresses due to step input of temperature on the boundaries of a homogeneous transversely isotropic circular disc is investigated by applying Laplace transform technique in the context of generalized theories of thermo-elasticity. The inverse of the transformed solution is carried out by applying a method of Bellman et al. The stresses are computed numerically and presented graphically in a number of figures. A comparison of the results for different theories (CTE, CCTE, TRDTE(GL), TEWED(GN)) and the effect of anisotropy on the stresses are also presented. When the material is isotropic and outer radius of the disc tends to infinity, the corresponding result agrees with that of existing literature. 相似文献
724.
This paper deals with determining various time-varying parameters that are instrumental in introducing noise and vibration in a helical gear system. The most important parameter is the contact line variation, which subsequently induces friction force variation, frictional torque variation and variation in the forces at the bearings. The contact line variation will also give rise to gear mesh stiffness and damping variations. All these parameters are simulated for a defect-free and two defective cases of a helical gear system. The defective cases include one tooth missing and two teeth missing in the helical gear. The algorithm formulated in this paper is found to be simple and effective in determining the time-varying parameters. 相似文献
725.
Two fundamentally different versions of the method of multiple scales (MMS) are currently in use in the study of nonlinear resonance phenomena. While the first version is the widely used reconstitution method, the second version is proposed by Rahman and Burton [1]. Both versions of the second-order MMS are applied to the differential equation obtained for a parametrically excited cantilever beam with a lumped mass at an arbitrary position. The bifurcation and stability of the obtained response show the difference between the two versions. While the Hopf bifurcation phenomena with no jump is found in the case of second-order MMS version I, both jump-up and jump-down phenomena are observed in second-order MMS version II, which closely agree with the experimental findings. The results are compared with those obtained by numerically integrating the original temporal equation. 相似文献
726.
Pritish Kar 《Journal of Solid State Electrochemistry》2008,12(12):1611-1617
A multistage shrinking-core model is proposed for the electrodeoxidation of titanium dioxide to titanium. This takes place
through a series of steps from TiO2 to Ti3O5 to Ti2O3 to TiO to Ti. Ideally, the model would incorporate a number of shells of the above lower oxide phases with the shrinking
core of TiO2 in the center but this would be mathematically intractable. A simpler method would be to use the shrinking-core model for
each of the individual reductions. Taking the experimental parameters and diffusion coefficient of oxygen in the different
phases into account, an analytical solution is developed for the transient differential equation. The first ten eigenvalues
are taken into account for the computation of the series solution. This is then compared with a solution based on a pseudo-steady-state
approximation to the transient equations. Based on the results, for higher values (>0.01) of dimensionless applied current
density, I
d
, both the solutions disagree in terms of the time it takes for the core to shrink completely. The difference appears to be
decreasing with lower values of I
d
but for larger values of I
d
the pseudo-steady-state approximation fails to yield results close to the analytical solution. 相似文献
727.
Manoj Kumar Jyoti Prakash Kar In-Soo Kim Se-Young Choi Jae-Min Myoung 《Applied Physics A: Materials Science & Processing》2009,97(3):689-692
Based on the tunneling current model, a simplified current model is developed for MOS devices after soft breakdown (SBD).
The post-soft-breakdown current consists of modified direct tunneling current and Fowler Nordheim (FN) tunneling current.
Considering the change of gate oxide after soft breakdown, impacts of soft breakdown on the dielectric constant, and effective
electron mass of the gate oxide are discussed, and their values are obtained by fitting simulation results to experimental
data. It is found that the effective electron mass is decreased after soft breakdown due to damaged oxide, while the dielectric
constant is increased after soft breakdown due to interface distortion. In this way, the leakage current after soft breakdown
can be accurately calculated. The validity of the proposed model is confirmed by experimental results.
Z.L. Li currently is with the Department of Electrical and Electronic Engineering, University of Hong Kong. 相似文献
728.
A lumped parameter mathematical model is developed to relate the cut depth to the laser cutting parameters and material properties. The model takes into account the threshold power of the incident laser beam for the initiation of cutting and modifies an earlier cutting model so that it applies to a wide set of process parameters ranging from low to high laser powers and slow to fast cutting speeds. Plain steel is taken as an example to show the effects of various process parameters such as the laser power, spot size and cutting speed on the cut depth. Special emphasis is given to the effect of laser mode structure on its cutting capability. 相似文献
729.
A Hybrid Anion for Ionic Liquid and Battery Electrolyte Applications: Half Triflamide,Half Carbonate
Kaitlyn E. Gunderson‐Briggs Thomas Rüther Adam S. Best Mega Kar Craig Forsyth Ekaterina I. Izgorodiana Douglas R. MacFarlane Anthony F. Hollenkamp 《Angewandte Chemie (International ed. in English)》2019,58(13):4390-4394
The synthesis of a new imide type anion, methylcarbonate(trifluoromethylsulfonyl)imide (MCTFSI) is described and the physicochemical properties of its sodium and N‐butyl‐N‐methyl pyrrolidinium salts as well as structural information obtained by X‐ray diffraction studies of the sodium salt are discussed in terms of charge delocalisation, coordination chemistry and electrochemical behaviour with respect to the analogous imdides bis(trifluoromethanesulfonyl)imide (TFSI) and bis(fluorosulfonyl)imide (FSI). The insight obtained from studying the new anion informs and reemphasizes the concept of weakly coordinating anions and coordination chemistry in designing electrolyte salts. 相似文献
730.
Marcelo H. Kravicz Debora T. Balogh Mrityunjoy Kar Stefanie Wedepohl Maria Vitoria L. B. Bentley Marcelo Caldern 《Macromolecular bioscience》2019,19(10)
The development of polymers with low toxicity and efficient gene delivery remains a significant barrier of nonviral gene therapy. Modification and tuning of chemical structures of carriers is an attractive strategy for efficient nucleic acid delivery. Here, polyplexes consisting of plasmid DNA (pDNA) and dodecylated or non‐dodecylated polysuccinimide (PSI)‐based polycations are designed, and their transfection ability into HeLa cells is investigated by green fluorescent protein (GFP) expressing cells quantification. All cationic polymers show lower cytotoxicity than those of branched polyethyleneimine (bPEI). PSI and bPEI‐based polyplexes have comparable physicochemical properties such as size and charge. Interestingly, a strong interaction between dodecylated polycations and pDNA caused by the hydrophobic moiety is observed in dodecylated PSI derivatives. Moreover, the decrease of GFP expression is associated with lower dissociation of pDNA from polyplexes according to the heparin displacement assay. Besides, a hydrophobization of PSI cationic derivatives with dodecyl side chains can modulate the integrity of polyplexes by hydrophobic interactions, increasing the binding between the polymer and the DNA. These results provide useful information for designing polyplexes with lower toxicity and greater stability and transfection performance. 相似文献