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排序方式: 共有1175条查询结果,搜索用时 125 毫秒
21.
A one‐dimensional steady‐state model is developed for the prediction of axial variation of the gas holdup in flotation column froths. Froth is considered as an inverse fluidized bed of bubbles and hence the frictional pressure gradient is obtained based on the energy balance. Pressure gradient can also be obtained from the Ergun equation with adjustable constants. The model correctly captures the effect of superficial gas velocity, superficial liquid velocity and bubble diameter on the variation of the gas holdup along the froth height. The predictions of the model are in agreement with the experimental data from the literature. 相似文献
22.
The glass transition temperatures (Tgs) of polystyrene (PS) and styrene/methyl methacrylate (S/MMA) random copolymer films are characterized by intrinsic fluorescence, i.e., monomer fluorescence from an excited-state phenyl ring and excimer fluorescence from an excited-state dimer of two phenyl rings. The Tg is determined from the intersection of the rubbery- and glassy-state temperature dependences of the integrated fluorescence intensity measured upon cooling from an equilibrated state. With PS, the effects of nanoconfinement on Tg and the transition strength agree with results from studies using probe fluorescence and ellipsometry. The Tg-nanoconfinement effect is “tuned” by copolymer composition. As S-content is reduced from 100 mol% to 22 mol%, the confinement effect changes from a reduction to an enhancement of Tg relative to bulk Tg. Intrinsic fluorescence is also a powerful tool for characterizing relaxation of residual stresses. Stresses induced by spin coating affect local conformations, which in turn affect excimer and monomer fluorescence and thereby integrated intensity. The heating protocol needed to achieve apparently equilibrated local conformations is determined by equivalence in the integrated intensities obtained upon heating and subsequent cooling. While partial stress relaxation occurs upon heating in the glassy state, full relaxation of local conformations requires that a film be heated above Tg for times that are long relative to the average cooperative segmental relaxation time. For example, in thin and ultrathin films, equilibration is achieved by heating slowly (∼1 K/min) to 15-20 K above Tg. Dilute solution fluorescence of PS and S/MMA copolymers is also characterized and compared to reports in the literature. 相似文献
23.
Manish Roy 《Journal of Thermal Spray Technology》2002,11(3):393-399
The objective of the present work was to determine the dynamic hardness of WC-Co coatings from the dynamic hardness of the
coating substrate system. It was also the purpose of this work to evaluate the influence of coating composition, coating thickness,
and substrate materials on the dynamic hardness of the coating. To achieve the above-mentioned objectives, WC-12%Co and WC-17%Co
coatings were deposited by detonation spraying on three different substrate materials: mild steel, commercially pure (CP)
aluminum, and CP titanium. The dynamic hardness of the coating/substrate composite was evaluated by a drop weight system.
The dynamic hardness of the coating independent of the substrate was determined from the dynamic hardness of the coating/substrate
composite. 相似文献
24.
Rao K. Srinivasa Madhuri T. Krishna Leela Sairam T. Manish Vali Shaik Shoukath Chand Ch. Gopi Sravani K. Girija 《Microsystem Technologies》2022,28(12):2697-2704
Microsystem Technologies - In this paper, we have designed and simulations of RF MEMS shunt switch. The electro-mechanical and electromagnetic analysis of the switch have been done using COMSOL... 相似文献
25.
The superconducting properties of Nb2PdS5 superconductor have been investigated with Ni doping at Pd site All the bulk polycrystalline Nb2Pd1?xNix S 5 (0 = x ≤ 0.10) samples are crystallized in singlephase monoclinic structure. The electrical resistivity and magnetic measurements of Nb2Pd1?xNix S 5 (0 = x ≤ 0.15) were carried out to study the variation of superconducting critical parameters with Ni doping. Superconductivity in Nb2PdS5 sample completely disappears for x ≥ 0.15. We observed that the ratio of upper critical field to transition temperature decreases with increasing Ni concentration. Also, the magnetization study of Nb2Pd1?xNix S 5 (0 = x ≤ 0.15) samples shows similar superconducting behaviour. In summary, the superconductivity in Nb2PdS5 sample is slightly varying with partial doping of Ni at Pd site in Nb2PdS5 superconductor. 相似文献
26.
Pradeep Kumar Gupta Dilip Sharma Shyam Lal Soni Rahul Goyal Dheeraj Kishor Johar 《Clean Technologies and Environmental Policy》2017,19(3):883-895
Old engines (Euro III or earlier) produce more emissions, and it will be difficult to entirely stop their usage especially in developing and under-developed nations; hence, it is desired that appropriate emission reduction technologies are tested on such engines to analyze their feasibility and economical acceptability. While most such studies have been conducted on constant speed stationary engines and modern engines, this study tried to analyze the effectiveness of an uncoated wall-flow type ceramic diesel particulate filter on a Euro-I, water-cooled, direct injection, variable speed, compression ignition engine in a laboratory set-up in India. Also, this study focused on diesel particulate filter regeneration by two methods: active regeneration by diesel injection in the particulate filter using an electronic control unit and off-board regeneration by taking out and heating the diesel particulate filter in an electrical resistance furnace at 650 °C for 10 h. The results, in the form of smoke emission, NOx emission and engine performance, obtained using both the regeneration methods were analyzed, and conclusions were drawn. It was found that using diesel particulate filter, particulate matter emissions (smoke) were almost entirely eliminated. It was also found that off-board regeneration had numerous advantages compared to active regeneration. Since a furnace would be needed for off-board regeneration, an exchange process for diesel particulate filter is suggested. 相似文献
27.
Huaying Ren Huan Wang Li Lin Miao Tang Shuli Zhao Bing Deng Manish Kumar Priydarshi Jincan Zhang Hailin Peng Zhongfan Liu 《Nano Research》2017,10(4):1189-1199
In the chemical vapor deposition growth of large-area graphene polycrystalline thin films,the coalescence of randomly oriented graphene domains results in a high density of uncertain grain boundaries (GBs).The structures and properties of various GBs are highly dependent on the misorientation angles between the graphene domains,which can significantly affect the performance of the graphene films and impede their industrial applications.Graphene bicrystals with a specific type of GB can be synthesized via the controllable growth of graphene domains with a predefined lattice orientation.Although the bicrystal has been widely investigated for traditional bulk materials,no successful synthesis strategy has been presented for growing two-dimensional graphene bicrystals.In this study, we demonstrate a simple approach for growing well-aligned large-domain graphene bicrystals with a confined tilt angle of 30° on a facilely recrystallized single-crystal Cu (100) substrate.Control of the density of the GBs with a misorientation angle of 30° was realized via the controllable rapid growth of subcentimeter graphene domains with the assistance of a cooperative catalytic surface-passivation treatment.The large-area production of graphene bicrystals consisting of the sole specific GBs with a tunable density provides a new material platform for fundamental studies and practical applications. 相似文献
28.
Jun Cao Ayush Goyal Krista A. Novstrup Samuel P. Midkiff James M. Caruthers 《International journal of parallel programming》2009,37(2):127-152
Well designed domain specific languages have three important benefits: (1) the easy expression of problems, (2) the application
of domain specific optimizations (including parallelization), and (3) dramatic improvements in productivity for their users.
In this paper we describe a compiler and parallel runtime system for modeling the complex kinetics of rubber vulcanization
and olefin polymerization that achieves all of these goals. The compiler allows the development of a system of ordinary differential
equations describing a complex vulcanization reaction or single-site olefin polymerization reaction—a task that used to require
months—to be done in hours. A specialized common sub-expression elimination and other algebraic optimizations sufficiently
simplify the complex machine generated code to allow it to be compiled—eliminating all but 8.0% of the operations in our largest
program and enabling over 60 times faster execution on our largest benchmark codes. The parallel runtime and dynamic load
balancing scheme enables fast simulations of the model. 相似文献
29.
Manish Aggarwal 《国际智能系统杂志》2016,31(6):529-555
Several new aggregation operators are proposed in the context of multicriteria decision making (MCDM) in the linguistic domain. The proposed operators first infer the discrimination index, based on the extent of variability in the various linguistic evaluations against a criterion. This value is then utilized in the actual aggregation step to discriminate among the alternatives. Besides, the proposed operators also take into account the a priori weights associated with the criteria. The proposed concepts are illustrated through an example in group MCDM. 相似文献
30.
Non-linear optimization models have been recently proposed to derive crisp weights from fuzzy pairwise comparison matrices. In this paper, a TLBO (Teaching Learning Based Optimization) based solution is presented for solving an optimization model as a system of non-linear equations to derive crisp weights from fuzzy pairwise comparison matrices in AHP (Analytic Hierarchy Process). This fuzzy-AHP method is named as TLBO-1. It has been found that TLBO-1 can lead to inconsistent or less consistent weights. To solve the problem of inconsistent weights, a new constrained non-linear optimization model is proposed in this paper. This model is based on the min-max approach for fuzzy pairwise comparison ratios of weights. TLBO is again used to solve this optimization model, and crisp weights are derived. This fuzzy AHP method is named as TLBO-2. The effectiveness of the proposed model is illustrated by three examples. For each example, the consistency of the derived crisp weights is compared with other optimization models. The results show that the TLBO-2 method can derive more consistent weights for the fuzzy AHP based Multi-Criteria Decision Making (MCDM) systems as compared to the other optimization models. 相似文献