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121.
We study the propagation of weakly nonlinear waves in nonideal fluids, which exhibit mixed nonlinearity. A method of multiple scales is used to obtain a transport equation from the Navier–Stokes equations, supplemented by the equation of state for a van der Waals fluid. Effects of van der Waals parameters on the wave evolution, governed by the transport equation, are investigated. 相似文献
122.
Friction plays a key role in the efficiency and stability of the slip-controlled torque converter clutches. The effects of
friction on the dynamics and stability of a slip-controlled torque converter clutch system using a bifurcation-analysis-based
approach is presented in this paper. A three degree-of-freedom nonlinear driveline model with integral feedback action to
control the clutch slip speed has been utilized for this study. The clutch interface friction is dependent on the slip speed
and is a function of the static friction constant, μ
0, the low velocity friction constant μ
1, and the low velocity exponential rate, γ. Using one-parameter numerical continuation, local Hopf bifurcations of the subcritical type are observed as the friction
parameters μ
1 and γ were varied at low slip speeds. The continuation results are verified using simulations of the full nonlinear model. Stick-slip
and undesirable oscillations of the model inertia elements are observed for certain parameter values. As the slip speed is
increased, the bifurcation instability occurs at an increasingly higher value of μ
1 signifying an improved tolerance of negative friction gradient at higher slip speeds. Smaller exponential rates γ are tolerated at higher slip speeds before the bifurcation instability occurs. For the range of parameter values considered,
no bifurcations occur for a slip speeds higher than 3.4 and 4.5 rad/s with μ
1 and γ as the continuation parameters, respectively. These values of slip speeds are much lower than the system’s first mode of
torsional vibration of 16 Hz (≈100 rad/s). 相似文献
123.
Gaurav Thakur 《Journal of Functional Analysis》2011,260(8):2283-2299
We study some problems related to the effect of bounded, additive sample noise in the bandlimited interpolation given by the Whittaker-Shannon-Kotelnikov (WSK) sampling formula. We establish a generalized form of the WSK series that allows us to consider the bandlimited interpolation of any bounded sequence at the zeros of a sine-type function. The main result of the paper is that if the samples in this series consist of independent, uniformly distributed random variables, then the resulting bandlimited interpolation almost surely has a bounded global average. In this context, we also explore the related notion of a bandlimited function with bounded mean oscillation. We prove some properties of such functions, and in particular, we show that they are either bounded or have unbounded samples at any positive sampling rate. We also discuss a few concrete examples of functions that demonstrate these properties. 相似文献
124.
We consider a scheduling problem motivated by mining in remote off-grid areas. In this model, mines have pre-assigned mineral processing jobs and their own machine for executing these jobs. Each job also needs a certain amount of electricity in order to get completed. The electricity, on the other hand, is of limited supply and must be shared between the mines. We present a mathematical formulation of the problem and a Lagrangian relaxation based heuristic. Computational results which compares our heuristic with genetic algorithm and simulated annealing are also presented. 相似文献
125.
Paras DeshpandeDeepak Shukla M.K. Tiwari 《European Journal of Operational Research》2011,212(2):325-336
An efficient inventory planning approach in today’s global trading regime is necessary not only for increasing the profit margin, but also to maintain system flexibility for achieving higher customer satisfaction. Such an approach should hence be comprised of a prudent inventory policy and clear satisfaction of stakeholder’s goals. Relative significance given to various objectives in a supply chain network varies with product as well as time. In this paper, a model is proposed to fill this void for a single product inventory control of a supply chain consisting of three echelons. A generic modification proposed to the membership functions of the fuzzy goal-programming approach is used to mathematically map the aspiration levels of the decision maker. The bacterial foraging algorithm has been modified with enhancement of the algorithms’ capability to map integer solution spaces and utilised to solve resulting fuzzy multi-objective function. An illustrative example comprehensively covers various decision scenarios and highlights the underlying managerial insights. 相似文献
126.
Sathiya M Prakash AS Ramesha K Tarascon JM Shukla AK 《Journal of the American Chemical Society》2011,133(40):16291-16299
Functionalized multiwalled carbon nanotubes (CNTs) are coated with a 4-5 nm thin layer of V(2)O(5) by controlled hydrolysis of vanadium alkoxide. The resulting V(2)O(5)/CNT composite has been investigated for electrochemical activity with lithium ion, and the capacity value shows both faradaic and capacitive (nonfaradaic) contributions. At high rate (1 C), the capacitive behavior dominates the intercalation as 2/3 of the overall capacity value out of 2700 C/g is capacitive, while the remaining is due to Li-ion intercalation. These numbers are in agreement with the Trasatti plots and are corroborated by X-ray photoelectron spectroscopy (XPS) studies on the V(2)O(5)/CNTs electrode, which show 85% of vanadium in the +4 oxidation state after the discharge at 1 C rate. The cumulative high-capacity value is attributed to the unique property of the nano V(2)O(5)/CNTs composite, which provides a short diffusion path for Li(+)-ions and an easy access to vanadium redox centers besides the high conductivity of CNTs. The composite architecture exhibits both high power density and high energy density, stressing the benefits of using carbon substrates to design high performance supercapacitor electrodes. 相似文献
127.
Ranjana Aggarwal Rajiv Kumar Sunil Kumar Gaurav Garg Ritu Mahajan Jitender Sharma 《Journal of fluorine chemistry》2011,132(11):965-972
5-Hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-thiocarboxamides 3 and 3-trifluoromethylpyrazol-1-thiocarboxamides 4, regioselectively obtained by the condensation of trifluoromethyl-β-diketones with thiosemicarbazide under neutral and acidic conditions, on further reaction with phenacyl bromides 5 afforded 4-aryl-(5-trifluoromethyl-pyrazol-1-yl)thiazoles 6 and 4-aryl-(3-trifluoromethyl-pyrazol-1-yl)thiazoles 7, respectively. Five 4,5-dihydropyrazoles (3a–e) and two pyrazolylthiazoles (6a and 6c) were tested against one Gram-positive and one Gram-negative bacteria to assess their in vitro antibacterial activity. Compounds 3a, 3b and 3e showed moderate antibacterial activity against Gram-positive bacterium, Bacillus pumilus. 相似文献
128.
Prabodh Shukla 《Journal of statistical physics》1993,71(3-4):705-717
We present an analysis of the parallel dynamics of the Hopfield model of the associative memory of a neural network without recourse to the replica formalism. A probabilistic method based on the signal-to-noise ratio is employed to obtain a simple recursion relation for the zero temperature as well as the finite temperature dynamics of the network. The fixed points of the recursion relation and their basins of attraction are found to be in fairly satisfactory agreement with the numerical simulations of the model. We also present some new numerical results which support our recursion relation and throw light on the nature of the ensemble of the network states which are optimized with respect to single spin flips. 相似文献
129.
Nadarajah Narendran Chonghua Zhou Stephen Letcher Arun Shukla 《Optics and Lasers in Engineering》1995,22(2)
An experimental study was conducted to investigate the applicability of fiber-optic acoustic sensors to detect internal flaws in polymeric materials. A polarimetric fiber-optic sensor embedded in a plexiglass model received the acoustic signals generated by an ultrasonic transducer. It is shown that proper control of the polarization and phase of the optical beam is required to obtain meaningful results from the amplitude of the fiber-optic sensor signal. The sensor has shown promising results in determining acoustical properties of plexiglass and locating internal defects. The attractive feature of this sensing scheme is that the optical fibers are not modified prior to embedding. Therefore, they preserve their mechanical properties which makes the embedding process much easier. 相似文献
130.
We show, using semiclassical methods, that as a symmetry is broken, the transition between universality classes for the spectral
correlations of quantum chaotic systems is governed by the same parametrization as in the theory of random matrices. The theory
is quantitatively verified for the kicked rotor quantum map. We also provide an explicit substantiation of the random matrix
hypothesis, namely that in the symmetry-adapted basis the symmetry-violating operator is random. 相似文献