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41.
Ashish Bhaskar Edward Chung André‐Gilles Dumont 《Computer-Aided Civil and Infrastructure Engineering》2011,26(6):433-450
Abstract: This article presents a methodology that integrates cumulative plots with probe vehicle data for estimation of travel time statistics (average, quartile) on urban networks. The integration reduces relative deviation among the cumulative plots so that the classical analytical procedure of defining the area between the plots as the total travel time can be applied. For quartile estimation, a slicing technique is proposed. The methodology is validated with real data from Lucerne, Switzerland and it is concluded that the travel time estimates from the proposed methodology are statistically equivalent to the observed values. 相似文献
42.
This paper presents the results on in-situ synthesis of refractory metal-intermetallic composites (RMICs), Mo-16Cr-4Si and Mo-11Cr-9Si (wt.%) multiphase alloys and their characterization. The alloys were prepared from the oxides of molybdenum and chromium by their coreduction with Si as reductant. Exothermic nature of the synthesis reactions resulted in the formation of consolidated composite as a product in a single step. As-reduced alloys were remelted by arc melting and heat treatment was given. The evolution of phases and the microstructure were studied by XRD, SEM, and EDS analysis. The multiphase microstructure consist of the silicide phases (Mo,Cr)3Si + (Mo,Cr)5Si3 for hypereutectic and (Mo,Cr)3Si phase distributed in bcc matrix comprising essentially a solid solution of (Mo,Cr) for hypo-peritectic composition. Comparative studies of the synthesized alloys were also carried out to the composition, phases, microstructure, hardness and their oxidation behavior. 相似文献
43.
Dinesh Prasad D. R. Bhaskar A. K. Singh 《Analog Integrated Circuits and Signal Processing》2009,61(3):309-313
An universal multi input single output type multifunction biquad is proposed. The proposed configuration employs only one
current differencing transconductance amplifier as the active element, two capacitors and three resistors. The circuit realizes
all five filter functions (i.e. Low Pass, High Pass, Band Pass, Notch and All Pass) without changing the circuit topology.
The natural frequency ω0 is independently and electronically tunable. The workability of the proposed multifunction biquad has been verified using
SPICE simulation. 相似文献
44.
S. B. Majumder P. S. Dobal B. Roy S. Bhaskar R. S. Katiyar Amar Bhalla 《Ferroelectrics Letters Section》2001,28(3):85-92
We have studied the effect of rare earth dopants (Nd, Gd and Ce) on the phase formation behavior and electrical properties of sol-gel derived Pb1.05(Zr0.53Ti0.47)O3 thin films. In all these films the perovskite phase is obtained up to 5 at% doping and beyond that pyrochlore phase was found to coexist with the perovskite phase. Ce and Gd doping(1-2 at%) exhibited improved ferroelectric and dielectric properties as compared to the undoped PZT films. Nd doping (2 at%) was found to be effective to increase the retained switchable polarization of undoped PZT from 63% to 84%. The transition temperature of undoped PZT film was found to be reduced with Nd doping. The Nd doped films also exhibited typical relaxor behavior and a diffuse phase transition, characteristic of the relaxor material. Introduction of Nd into the PZT lattice probably introduces disorder in the B site of ABO3 lattice which causes the observed relaxor behavior 相似文献
45.
Soft-Decision Decoding of Punctured Convolutional Codes in Asynchronous-CDMA Communications Under Perfect Phase-Tracking Conditions 总被引:1,自引:0,他引:1
Vidhyacharan Bhaskar 《International Journal of Wireless Information Networks》2006,13(3):229-237
In this paper, the performance of punctured convolutional codes of short constraint lengths is discussed. The punctured codes are used to provide error protection to a particular user in an asynchronous CDMA system. A perfect phase reference is assumed to be available throughout this paper. A slow fading Rician channel is assumed. Maximum likelihood decoding through a Viterbi algorithm is used to decode the information symbols. Soft-decision decoding of punctured convolutional codes is considered in this paper. The upper bounds with Viterbi decoding are derived and plotted for the various punctured codes considered. The simulated results are found to agree very well with their upper and lower bounds. 相似文献
46.
Experimental work on post-breakdown bulk oscillations in n-type gold-doped phosphorus-compensated p+?i?n+ double-injection diodes is presented. An empirical relationship for the frequency of oscillation in this region is derived for the first time and discussed. 相似文献
47.
Kutty MG Bhaduri S Bhaduri SB 《Journal of materials science. Materials in medicine》2004,15(2):145-150
To be successful, an implant should be biocompatible, strong and contain surface pores to promote osseointegration. A one-step microwave sintering procedure of titanium powders was attempted in this work. The idea was to take advantage of the peculiar way microwave couple with metallic powders, i.e. generating heat in the interior of the sample and dissipating it away through the surface. This non-conventional heating of titanium powder produced a dense core with surface porosity. The dense core provides the strength while the surface pores promote bone growth. The experiments were carried out in a semi-industrial grade microwave cavity using a alpha-SiC susceptor. Power levels of 1-1.5 kW, and soaking periods of approximately 30 min were used. Microstructural characterization was carried out by a scanning electron microscope. The sintered titanium had gradient porosity on the surface with a thickness of about 100-200 microm depending on the microwave power. The pores were interconnected with size ranging from 30 to 100 microm. This kind of microstructure is favorable for cell growth. Tensile strength values as high as 400 MPa were obtained for these samples. 相似文献
48.
Spectral Efficiency Evaluation for MRC Diversity Schemes Over Generalized Rician Fading Channels 总被引:1,自引:0,他引:1
Vidhyacharan Bhaskar 《International Journal of Wireless Information Networks》2007,14(3):209-223
In this paper, closed-form expressions for the capacities per unit bandwidth for generalized Rician fading channels are derived
for power and rate adaptation, constant transmit power, channel inversion with fixed rate, and truncated channel inversion
adaptation policies. The closed-form solutions are derived for the single antenna reception (without diversity combining)
and maximal-ratio combining (MRC) diversity cases. Truncated channel inversion adaptation policy is the best policy for the
single antenna reception case, while the channel inversion with fixed rate policy is the best policy for the MRC diversity
case. Constant transmit power policy provides the lowest spectral efficiency as compared to the other policies with and without
diversity. 相似文献
49.
50.
Internet advertising is a sophisticated game in which the many advertisers “play” to optimize their return on investment. There are many “targets” for the advertisements, and each “target” has a collection of games with a potentially different set of players involved. In this paper, we study the problem of how advertisers allocate their budget across these “targets”. In particular, we focus on formulating their best response strategy as an optimization problem. Advertisers have a set of keywords (“targets”) and some stochastic information about the future, namely a probability distribution over scenarios of cost vs click combinations. This summarizes the potential states of the world assuming that the strategies of other players are fixed. Then, the best response can be abstracted as stochastic budget optimization problems to figure out how to spread a given budget across these keywords to maximize the expected number of clicks. We present the first known non-trivial poly-logarithmic approximation for these problems as well as the first known hardness results of getting better than logarithmic approximation ratios in the various parameters involved. We also identify several special cases of these problems of practical interest, such as with fixed number of scenarios or with polynomial-sized parameters related to cost, which are solvable either in polynomial time or with improved approximation ratios. Stochastic budget optimization with scenarios has sophisticated technical structure. Our approximation and hardness results come from relating these problems to a special type of (0/1, bipartite) quadratic programs inherent in them. Our research answers some open problems raised by the authors (in Algorithmica, 58(4):1022–1044, 2010). 相似文献