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排序方式: 共有140条查询结果,搜索用时 15 毫秒
1.
The motion equations governing the dynamical behavior of a viscoelasticTimoshenko beam with finite deformation are derived and simplified byGalerkin method. The viscoelastic material is assumed to obey thethree-dimensional fractional derivative constitutive relation. Thedynamical behaviors of the simplified systems with order 1 and order 2are numerically computed and compared by using the computational methodpresented by the authors. The dynamical behaviors of the systems areuniform qualitatively, but there is a little deviation quantitatively.And the truncated system with order 1 is safer than the one of order 2.It is also shown that the lower order system is reasonable. Theinfluences of the load parameter and the fractional derivative parameter(material parameter) on the deflection of the beam are consideredrespectively. The numerical methods in nonlinear dynamics, such as phasediagram, and Poincaré section, are applied to reveal dynamical behaviorsof the nonlinear viscoelastic Timoshenko beam. There are plenty ofdynamical behaviors, such as periodicity, bifurcation, quasi-periodicityand chaos in the dynamical system. 相似文献
2.
Sk S. Hossain Chang-Jun Bae P. K. Roy 《International Journal of Applied Ceramic Technology》2021,18(5):1783-1791
Lightweight insulation refractories are essential for high-temperature performance to reduce energy consumption. This study investigates a new insulation material, that is, solid waste rice husk ash (RHA) derived lightweight refractory castable, replacing traditional insulation refractory brick. The RHA is generated after the burning of rice husk as biomass fuel. The RHA is used as an aggregate and alkali-extracted silica sol from RHA as a binder to fabricate the insulation castable. The nanosilica containing (~30 wt%) sol is employed to synthesize the refractory castable by varying the sol amount (2.5-12.5 wt% silica from sol). The castable specimens are cast by a vibro-caster and fired at 900-1200°C in a muffle furnace. The physic-mechanical and thermal conductivity (κ) of the castable is investigated. At 1100°C with 10 wt% dry sol retaining sample shows an excellent apparent porosity (~65%), low bulk density (~ 0.8 g/cm3), and κ (0.136 W/m k) with sustainable compressive strength (6 MPa). The acquired results are a good match with the literature (other wastes-derived insulation materials) and industrial (silica insulation brick) obtained data. These promising outcomes may inspire the refractory industries for using RHA as an aggregate and RHA extracted sol as a binder for making insulation castable. 相似文献
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Yu-YueDu Chang-JunJiang 《计算机科学技术学报》2004,19(2):0-0
Temporal colored Petri nets, an extension of temporal Petri nets, are introduced in this paper. It can distinguish the personality of individuals (tokens), describe clearly the causal and temporal relationships betwee nevents in concurrent systems, and represent elegantly certain fundamental properties of concurrent systems, such as eventuality and fairness. The use of this method is illustrated with an example of modeling and formal verification of an online stock trading system. The functional correctness of the modeled system is formally verified based on the temporal colored Petri net model and temporal assertions. Also, some main properties of the system are analyzed. It has been demonstrated sufficiently that temporal colored Petri nets can verify efficiently some time-related properties of concurrent systems, and provide both the power of dynamic representation graphically and the function of logical inference formally. Finally. future work is described. 相似文献
8.
Lu-Xi Zhang Chang-Jun Fan Ping Liu Guo-Ping Yang Chen Ren Rui-Ting Liu 《Inorganic chemistry communications》2010,13(8):914-918
The reaction between ErCl3·6H2O and H2bmdc (H2bmdc = benzimidazole-5,6-dicarboxylic acid) produced two distinct complexes: 1D helical complex {[Er(Hbmdc)(bmdc)(H2O)3]·3H2O}n (1) obtained under hydrothermal condition at 160 °C and discrete complex [Er2(Hbmdc)2(bmdc)2(H2O)8]·8H2O (2) under ambient temperature, evaporated from the mother liquor of 1. The crystal structures of the complexes were determined by X-ray single-crystal diffraction. Through comparison of complexes 1 and 2, we found that enhanced temperature favors the formation of higher dimensional products and lower amount of coordinated water. Both complexes are characterized by IR, elemental analysis, X-ray powder diffraction and thermogravimetric analysis. 相似文献
9.
A P204(D2EHPA) diluted with sulfonated kerosene was used for the selective extraction of molybdenum from an acidic Ni–Mo ore leach solution that was reduced using sodium thiosulfate. The results indicate that P204(D2EHPA) is an effective extractant for the extraction of molybdenum. The extraction of Mo is more than 90 % at pH of 0.5, contact time of 10 min, and organic-toaqueous phase(O/A) ratio of 1:1 with 10 vol% P204(D2EHPA). Molybdenum in the loaded organic phase can be effectively stripped with ammonium acid carbonate solution, and the stripping of molybdenum with 60 g L-1 ammonium acid carbonate solution is 94.67 % at O/A ratio of 2:1 and contact time of 10 min. 相似文献
10.
Chang-Jun Ahn Dongsoo Har Tatsuya Omori Ken-ya Hashimoto 《Digital Signal Processing》2012,22(3):518-525
In a wireless network, the signals transmitted from one sender to different users have independent channel fluctuation characteristics. The diversity that exists between users is called multiuser diversity and can be exploited by the sender to enhance the capacity of wireless network. In multiuser diversity OFDMA system, exploiting channel fluctuation diversity is in essence done by selecting the user with the strong subcarrier channels. The individual subcarrier selection for each user can achieve the best system performance but high signaling overhead and high system complexity are required. On the other hand, the adaptive subcarrier block method achieves worse BER than that of individual subcarrier selection. This is because the selected block contains the poor channel subcarriers. To overcome this problem, in this paper, we propose an adaptive subcarrier block selection with frequency symbol spreading for an OFDMA system. 相似文献