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41.
Balakrishnan Meera Puliafito Antonio Trivedi Kishor Viniotis Yannis 《Telecommunication Systems》1997,7(1-3):105-123
The B‐ISDN will carry a variety of traffic types: the Variable Bit Rate traffic (VBR), of which compressed video is an example,
Continuous Bit Rate traffic (CBR), of which telemetry is an example, Data traffic, and Available Bit Rate traffic (ABR) that
represents aggregate data traffic with very limited guarantees on quality. Of these, VBR and CBR have timing constraints and
need synchronous bandwidth; data traffic is relatively delay insensitive. In this paper, we consider the VBR, Data and ABR
traffic types and obtain the cumulative distribution function (cdf) of the queueing delay experienced by a burst of ABR traffic
in the output buffer of an ATM switch. The cdf is used to trade off buffer loss probabilities against deadline violation probabilities
through adjusting the buffer size and (delay) deadline values. Large buffers result in low losses but queueing delays can
become excessive and cause a high level of deadline violations. Both losses and violations are detrimental and an operating
point must be chosen to achieve a balance. In this paper we study the nature of the trade off. We develop a stochastic Petri
net model assuming periodic burst arrivals for VBR and Poisson arrival processes for the Data and ABR traffic types at the
burst level, and solve the model analytically (numerically) using a decomposition approach. This decomposition, along with
the inherent decomposability of the tagged customer approach for obtaining the cdf opens up a possibility of carrying out
fast computations using a parallel machine for selecting the operating point each time that a call is admitted.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
42.
43.
Jugal Kishor I. C. Goyal R. L. Sawhney S. P. Singh M. S. Sodha M. Dayal 《国际能源研究杂志》1988,12(4):711-737
This paper presents a thermal model of a fixed dome biogas plant, with or without hot charging and having the ground surface above the plant, blackened and glazed. The rate of energy transfer, between the ground and the plant has been determined by electrical simulation experiments, using a small scale model of the plant (made of copper), suspended in copper sulphate solution. For hot charging a shallow solar pond, built on the ground has been considered. The monthly variation of the slurry temperature, corresponding to 1, 4, 8, 15 and 30 m3 plants have been evaluated for Madras, New Delhi and Srinagar, which correspond to typical hot, composite and cold climates; the following cases have been considered:
- 1 Bare plant, without hot charging and blackening/glazing of the ground, above the plant.
- 2 Plant, charged with hot slurry from a shallow solar pond.
- 3 Plant, with ground above blackened and glazed.
- 4 Plant, with ground above blackened and double glazed and also provision for heating the slurry by burning a part of the produced biogas.
44.
Amit Shinde George Church Mani Janakiram George Runger 《Quality and Reliability Engineering International》2011,27(7):885-893
As manufacturing transitions to real‐time sensing, it becomes more important to handle multiple, high‐dimensional (non‐stationary) time series that generate thousands of measurements for each batch. Predictive models are often challenged by such high‐dimensional data and it is important to reduce the dimensionality for better performance. With thousands of measurements, even wavelet coefficients do not reduce the dimensionality sufficiently. We propose a two‐stage method that uses energy statistics from a discrete wavelet transform to identify process variables and appropriate resolutions of wavelet coefficients in an initial (screening) model. Variable importance scores from a modern random forest classifier are exploited in this stage. Coefficients that correspond to the identified variables and resolutions are then selected for a second‐stage predictive model. The approach is shown to provide good performance, along with interpretable results, in an example where multiple time series are used to indicate the need for preventive maintenance. In general, the two‐stage approach can handle high dimensionality and still provide interpretable features linked to the relevant process variables and wavelet resolutions that can be used for further analysis. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
45.
p-CdTe thin films were prepared by spray pyrolysis under different ambient conditions and characterized using photoelectrochemical(PEC),X-ray diffraction(XRD),scanning electron microscopy,energy-dispersive analysis by X-ray(EDAX),and optical transmission studies.The different preparative parameters viz solution pH, solution quantity,substrate temperature and solution concentration have been optimized by the PEC technique in order to get good-quality photosensitive material.XRD analysis shows the polycrys... 相似文献
46.
The influence of substrate temperature and nozzle-to-substrate distance(NSD) on the structural,morphological, optical and electrical properties of Sb:SnO2 thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the(200) reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449(Ω·cm)-1,70%and 5.2×10-3□/Ω,respectively,were observed for a typical film deposited using optimal conditions(substrate temperature = 500℃and NSD = 30 cm). 相似文献
47.
Transparent conducting antimony doped tin oxide(Sb:SnO2) thin films have been deposited onto preheated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution.The structural, morphological,X-ray photoelectron spectroscopy,optical,photoluminescence and electrical properties of these films have been studied.It is found that the films are polycrystalline in nature with a tetragonal crystal structure having orientation along the(211) and(112) planes.Polyhedrons like grains appear in the FE-SEM images. The average grain size increases with increasing spraying quantity.The compositional analysis and electronic behaviour of Sb:SnO2 thin films were studied using X-ray photoelectron spectroscopy.The binding energy of Sn3d5/2 for all samples shows the Sn4+ bonding state from SnO2.An intensive violet luminescence peak near 395 nm is observed at room temperature due to oxygen vacancies or donor levels formed by Sb5+ ions.The film deposited with 20 cc solution shows 70%transmittance at 550 nm leading to the highest figure of merit(2.11×10-3Ω-1). The resistivity and carrier concentration vary over 1.22×10-3 to 0.89×10-3Ω·cm and 5.19×1020 to 8.52×1020 cm-3,respectively. 相似文献
48.
The influence of substrate temperature and nozzle-to-substrate distance (NSD) on the structural, morphological, optical and electrical properties of Sb:SnO2 thin films prepared by chemical spray pyrolysis has been analyzed. The structural, morphological, optical and electrical properties were characterized by using XRD, SEM, UV-visible spectrophotometry and Hall effect measurement techniques. It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the (200) reflection. The pyramidal crystallites formed due to coalescence were observed from SEM images. The values of highest conductivity, optical transmittance and figure of merit of about 1449 (Ω·cm)-1, 70 % and 5.2 × 10-3 □/Ω, respectively, were observed for a typical film deposited using optimal conditions (substrate temperature D 500 ℃ and NSD D 30 cm). 相似文献
49.
S.S. Shinde 《Materials Research Bulletin》2011,46(10):1734-1737
A metal-semiconductor-metal photoconductive detector was fabricated using high quality Ga-doped ZnO film epitaxially grown onto alumina substrate by spray pyrolysis. The photocurrent increases linearly with incident power density for more than two orders of magnitude. Reflectance and photocurrent measurements were carried out to study optoelectronic properties of Ga-doped ZnO thin film. Both spectra are consistent with each other showing good response in UV than visible region. Peak responsivity of about 1187 A/W at 5 V bias for 365 nm light was obtained in UV region. 相似文献
50.
Kishor K. Mehta 《Nuclear Engineering and Design》1975,33(3):403-421
Nonlinear simulation has been applied to the control study of an organic-cooled Canadian CANDU reactor. The study was carried out as an integral part of an overall design study. The control characteristics of the power plant were studied for reactor start-up, pump failures, reactor trips and various rates of power change. The response of the power plant to these disturbances is discussed. 相似文献