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排序方式: 共有837条查询结果,搜索用时 15 毫秒
51.
Two-dimensional incompressible Navier-Stokes equations are solved using SIMPLER method in the intrinsic curvilinear coordinates
system to study the unsteady viscous flow physics over two-dimensional ellipses Unsteady viscous flows over various thickness-to-chord
ratios of 06, 08, 10, and 1 2 elliptic cylinders are simulated at different Reynolds numbers of 200, 400, and 1,000 This study
is focused on the understanding the effects of Reynolds number and elliptic cylinder thickness on the drag and lift forces
The present numerical solutions are compared with available experimental and numerical results and show a good agicement Through
this study, it is observed that the Reynolds number and the cylinder thickness affect significantly the frequencies of the
force oscillations as well as the mean values and the amplitudes of the drag and lift forces 相似文献
52.
Theoretical expressions for the currents excited on the top and bottom surfaces of a coaxial-probe-fed patch antenna are derived. Exact expressions for the far-zone field in terms of the total current on the patch are found. The analysis is specialized to a two-dimensional case. Detailed results for current, far-zone fields, and radiating-aperture admittance have been computed for this two-dimensional antenna model using the conjugate-gradient-fast Fourier transform (CG-FFT) technique. For a thick-substrate antenna it is found that the upper surface current on the patch is significant. Under this condition the traditional approximation of the total current by the bottom surface current alone may be in considerable error 相似文献
53.
54.
The hot water process has recovered approximately 90% of the bitumen in oil sands, but the remaining 10% of bitumen and naphtha has been lost to the tailings pond. Recovery of bitumen and non-bituminous combustibles (NBC) from centrifuge, scroll and final tailings has been considered. The effects of four sequestering agents, and of chemical additives such as CaCl2 and FeCl3 on the flotation behavior of bitumen, NBC and minerals in these tailings have been investigated. A simple method of isolating NBC materials has been developed. The flotation of both bitumen and NBC was enhanced by phosphate treatment and depressed by EDTA. NBC was characterized by its physical properties, energy content, functionality and chemical analysis. A conceptual model explains the interactions between the bitumen, minerals and NBC fractions present in tailings slurries. 相似文献
55.
Suman Roy Janardan Misra Indranil Saha 《Software Testing, Verification and Reliability》2016,26(8):548-571
We revisit the problem of real‐time verification with dense‐time dynamics using timeout and calendar‐based models and simplify this to a finite state verification problem. We introduce a specification formalism for these models and capture their behaviour in terms of semantics of timed transition systems. We discuss a technique, which reduces the problem of verification of qualitative temporal properties on infinite state space of a large fragment of these timeout and calender‐based transition systems into that on clock‐less finite state models through a two‐step process comprising of digitization and finitary reduction. This technique enables us to verify safety invariants for real‐time systems using finite state model checking avoiding the complexity of infinite state (bounded) model checking and scale up models without applying techniques from induction‐based proof methodology. In the same manner, we verify timeliness properties. Moreover, we can verify liveness for real‐time systems, which are not possible by using induction with infinite state model checkers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
56.
Indranil Saha Lokesh Kumar Sambasivan Subhas Kumar Ghosh Ranjeet Kumar Patro 《Wireless Networks》2010,16(6):1511-1524
In wireless multi-hop and ad-hoc networks, minimizing power consumption and at the same time maintaining desired properties
of the network topology is of prime importance. In this work, we present a distributed algorithm for assigning minimum possible
power to all the nodes in a static wireless network such that the resultant network topology is k-connected. In this algorithm, a node collects the location and maximum power information from all nodes in its vicinity,
and then adjusts the power of these nodes in such a way that it can reach all of them through k optimal vertex-disjoint paths. The algorithm ensures k-connectivity in the final topology provided the topology induced when all nodes transmit with their maximum power is k-connected. We extend our topology control algorithm from static networks to networks having mobile nodes. We present proof
of correctness for our algorithm for both static and mobile scenarios, and through extensive simulation we present its behavior. 相似文献
57.
In wavelength routed optical networks, the number of wavelength channels is limited due to several constraints and each wavelength
as well as each lightpath support traffic in the Gbps range. On the other hand, the traffic requested by an individual connection
is still in the Mbps range. Therefore, to utilize the network resources (such as bandwidth and transceivers) effectively,
several low-speed traffic streams have to be efficiently groomed or multiplexed into one or more high-speed lightpaths. The
grooming problem of a static demand is considered as an optimization problem. In this work, we have investigated the traffic
grooming problem with the objective of maximizing the network throughput for wavelength-routed mesh networks and map this
problem to the clique partitioning problem. We have proposed an algorithm to handle general multi-hop static traffic grooming
based on the clique partitioning concept. The efficiency of our approach has been established through extensive simulation
on different sets of traffic demands with different bandwidth granularities for different network topologies and compared
the approach with existing algorithms. 相似文献
58.
Shivareddy Induri Sonali Sengupta Jayanta K. Basu 《Journal of Industrial and Engineering Chemistry》2010,16(3):467-473
The purpose of this work is to study the kinetics of the esterification of maleic anhydride with methanol to form dimethyl maleate in a batch reactor in the presence of H-Y zeolite as a catalyst. This is a series-parallel type multiple reaction where, the first reaction involves the formation of monomethyl maleate that further reacts with alcohol to form dimethyl maleate. Dimethyl maleate was found to be the only product in the reaction mixture. Temperature, speed of agitation, catalyst size, reactant mole ratio and catalyst loading have pronounced effect on the rate of the reaction. A homogeneous rate model and heterogeneous rate models have been derived and fitted with the experimental data. The activation energy was found to be 44.65 kJ/mol. 相似文献
59.
Dipankar Saha Amretashis Sengupta Sitangshu Bhattacharya Santanu Mahapatra 《Journal of Computational Electronics》2014,13(4):862-871
We report the effect of topological as well as lattice vacancy defects on the electro-thermal transport properties of the metallic zigzag graphene nano ribbons at their ballistic limit. We employ the density function theory–Non equilibrium green’s function combination to calculate the transmission details. We then present an elaborated study considering the variation in the electrical current and the heat current transport with the change in temperature as well as the voltage gradient across the nano ribbons. The comparative analysis shows, that in the case of topological defects, such as the Stone-Wales defect, the electrical current transport is minimum. Besides, for the voltage gradient of 0.5 Volt and the temperature gradient of 300 K, the heat current transport reduces by \({\sim }62\,\%\) and \({\sim }50\,\%\) for the cases of Stones-Wales defect and lattice vacancy defect respectively, compared to that of the perfect one. 相似文献
60.
We analyze charity requests registered on the Random Acts of Pizza online community and examine the content of postings and non-content characteristics to identify features that are associated with the success of donation. We find that the presence of rational and credible appeals in a message increases the likelihood of receiving a donation, whereas the mere presence of negative emotional appeal does not do so. Our research is useful for those who like to make persuasive charity requests on online platforms. 相似文献