Analytical Water Shortage Probabilities and Distributions of Various Lead Times for a Water Supply Reservoir

Water Resources Management - Reducing the negative impacts of water shortages is the primary concern of water supply reservoir operation. This study aims to propose a theoretical framework of water...     

Study on related simulations between exit characteristics and evacuation performance

Microsystem Technologies - During a building disaster, building occupants typically engage in herd behavior, which results in friction, pushing, and even injury and death. Building occupants...     

Two-machine flowshop scheduling to minimize mean flow time under simple linear deterioration

A real industrial production phenomenon, referred to as deteriorating jobs, has drawn increasing attention. However, most research on this issue considers only single-machine problems. Motivated by this limitation, this paper considers a simple linear deterioration model in a two-machine flowshop where the objective is to minimize the mean flow time. Several dominance rules and three lower bounds are proposed to speed up the search for an optimal solution, and several heuristic algorithms are provided to derive near-optimal solutions. In addition, a computational experiment is conducted to evaluate their performances. Results indicate that the algorithms perform well, and a combined heuristic algorithm is recommended for practitioners.     

Measurement of the Reynolds stress structure and turbulence characteristics of the wind above a two-dimensional trapezoidal shape of hill

Wind tunnel experiments were carried out to measure the mean velocity and turbulence structure of the wind flow over a two-dimensional trapezoidal shape of hill. The quadrant analysis technique was employed to analyze the structure of the Reynolds stress. Analysis of the turbulent velocity spectrum of the wind above the hill under different wind attack angles is conducted. The fractional speed-up ratios of the present measured results are found in agreement with the wind tunnel data of Lemelin et al. (J. Wind Eng. Ind. Aerodyn. 28 (1988) 117) for the case of the wind attack angle of 30°. Measurements of the mean velocity profiles disclose that the speed-up phenomenon is mostly manifest at Z/H=0.6 for the case of wind attack angle of 10°. Turbulence intensity profiles measured at different locations show that the turbulence intensity decreases as shifting from far upstream location of the hill (X/H=−20) to the downstream location at the center of hill (X/H=0). The decrease of the turbulence intensity is obviously at the distance close to the surface of the hill. Results of the quadrant analysis indicate that the sweep and ejection events are the major contributors to the Reynolds stress. Others like inward and outward interaction events make negative contributions. The values of the stress fractions of ejection and sweep events become the lowest as the wind attack angle is 20°. Analysis of the turbulent velocity power spectrum density shows that the spectrum density is increasing in the lower-frequency region as the wind attack angle increases. The power spectrum density is found to decrease for increase in the wind attack angle at the higher-frequency region.     

CERAMICS AS CANDIDATE STRUCTURAL MATERIALS FOR CRYOGENIC APPLICATIONS

1.Iatroductlonheaapportmateriai8lhsuperconductingmagnetsystems,thereareatleasttwofactorswhichtnustbeeohe1dered:thefirstlstheheatleakthroughthesupp0rt.Itisnecessarytoeefortamater1aiwhooeeseentlalthermaleonductlv1tyissinall.Thesec0ndisitsmechanicalPropertles.Itl.deslrabletoselectamaterialwhosesttengthandt0ughnessishighen0ught0bedthe.tatlcanddynam1cloadsll-4].Flbrwrelnforcedplast1cs(FRPs)havebeenwidelyinvestigated,owingt0theirhighspeclficatraphandforthermalconductivityl51.However,thedisadvantag…     

A Bayesian procedure for process capability assessment

The usual practice of judging process capability by evaluating point estimates of some process capability indices has a flaw that there is no assessment on the error distributions of these estimates. However, the distributions of these estimates are usually so complicated that it is very difficult to obtain good interval estimates. In this paper we adopt a Bayesian approach to obtain an interval estimation, particularly for the index C_pm. The posterior probability p that the process under investigation is capable is derived; then the credible interval, a Bayesian analogue of the classical confidence interval, can be obtained. We claim that the process is capable if all the points in the credible interval are greater than the pre‐specified capability level ω, say 1.33. To make this Bayesian procedure very easy for practitioners to implement on manufacturing floors, we tabulate the minimum values of Ĉ_pm/ω, for which the posterior probability p reaches the desirable level, say 95%. For the special cases where the process mean equals the target value for C_pm and equals the midpoint of the two specification limits for C_pk, the procedure is even simpler; only chi‐square tables are needed. Copyright © 1999 John Wiley & Sons, Ltd.     

Circuit-limited oscillations at the onset of impurity breakdown in ultrapure p-Ge with an S-shaped current-field characteristic

Ultrapure p-Ge with doping concentration as low as 10¹¹ cm⁻³ is considered to investigate self-pulsating oscillations at the onset of impurity breakdown with respect to an S-shaped current-field characteristic. The associated nonlinear dynamics is computed within the two-impurity-level model with more convincing parameterization. The system undergoes a single Hopf bifurcation in the presence of a sufficiently large circuitry capacitance. As the operating point is controlled towards the breakdown threshold, no further bifurcations but a changeover of the periodic oscillation occurs from being sinusoidal to pulsating. Our approach also obtains agreeable results for n-GaAs with typically higher doping.