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International Multiconference of Engineers and Computer Scientists

作者： Zhao, Wenzhi Civil Aviat Univ China Management Study Ctr Tianjin Peoples R China

ISBN: (纸本)9789889867140

The rate of occupation and overflow is studied in this paper. A method of estimating the rate in statistics is reviewed first, which leads to find a problem in average computing. The signification of parameters in the method of estimating the overflow rate is explored from a referenced formula which may be converted into an obvious form. Then the simulation for computing the number of occupation and overflow is carried out to show the nature of the random distribution calculation with uncertainty. The conclusion is obtained that an aircraft with a proper capacity should be selected in order not to waste too many seats.

关键词： occupation rate overflow rate economical operation fleet capacity simulation

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Chernoff bounds for mean overflow rates

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QUEUEING SYSTEMS 2000年第1-4期34卷 301-326页

作者： Majewski, K Siemens Corp Res & Dev D-81730 Munich Germany

A number of independent traffic streams arrive at a queueing node which provides a finite buffer and a non-idling service at constant rate. Customers which arrive when the buffer is full are dropped and counted as overflows. We present Chernoff type bounds for mean overflow rates in the form of finite-dimensional minimization problems. The results are based on bounds for moment generating functions of buffer and bandwidth usage of the individual streams in an infinite buffer with constant service rate. We calculate these functions for regulated, Poisson and certain on/off sources. The achievable statistical multiplexing gain and the tightness of the bounds are demonstrated by several numerical examples.

关键词： buffer overflow overflow rate Chernoff bound leaky bucket regulator on/off source single server queue

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Winter temperature gradients in circular clarifiers

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WATER ENVIRONMENT RESEARCH 1998年第7期70卷 1274-1279页

作者： Wells, SA LaLiberte, DM Portland State Univ Portland OR 97207 USA

To understand the effect of temperature-induced density currents on circular clarifiers, a field study was performed on three uncovered circular tanks in Oregon during periods of low flow and high surface cooling. Temperatures were measured as a function of radial position and tank depth. Meteorological parameters were also measured to compute the surface heat flux from the water surface. Water temperatures in the tank were often 20 to 30 degrees C warmer than the equilibrium temperature. These studies showed that density currents and unstable temperature gradients were common. Surface temperatures were often approximately 1 degrees C cooler than bottom temperatures, The momentum and suspended solids of the inflow caused a density current that moved along the clarifier bottom and then rose near the middle of the tank. In the winter, this density current rose as a result of the decrease of initial momentum of the inflow, the buoyancy of the inflow after suspended solids had settled, and the geometry of the tank. Also, vertical velocities induced by surface cooling were two orders of magnitude greater than the overflow rate, suggesting that particles could be kept in suspension by convective currents.

关键词： sedimentation clarifier temperature suspended solids overflow rate density currents convective cooling heat loss

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Activated sludge process control - development of operational diagrams

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JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2007年第3期42卷 331-336页

作者： Jeyanthi, J. Saseetharan, M. K. Govt Coll Technol Dept Civil Engn Coimbatore 641013 Tamil Nadu India

Hindered batch settling experiments were performed on activated sludge generated from dairy wastewater and combined (Dairy-Domestic mixture 1:3) wastewater for different initial Mixed Liquor Suspended Solids (MLSS) concentrations from 2g/L to 20 g/L for varied Mean Cell Residence Time (MCRT) for 5 to 15 days. Bio kinetic coefficients of combined wastewater were determined using a bench scale Continous Flow Stirred Tank Reactor (CFSTR). Vesilind parameters were also determined experimentally. Operational diagrams for long-term fluctuations in plant inflow and substrate concentration have been prepared. The allowable overflow rate to prevent process failure can be predicted from the chart. The adjustments to be made in recycling ratio and MCRT in case of fluctuations could also be predicted from the operational diagrams. From the operating diagrams plotted for both dairy and combined wastewater, it was noticed that, combined wastewater treatment provide greater operational flexibility than treating dairy waste separately.

关键词： activated sludge process mean cell residence time overflow rate recycling ratio process control steady state

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Design of class-I sedimentation tanks

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JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE 1996年第1期122卷 71-73页

作者： Swamee, PK Tyagi, A NATL INST HYDRO ROORKEE 247667UTTAR PRADESHINDIA

The present practice for the design of primary settling tanks is based on the overflow rate corresponding to the percentage removal using isoremoval plots. The design procedure would be more rational if it were based on the removal efficiency and the scour criterion of the deposited particles. This technical note presents closed-form equations for the removal efficiency and scour velocity of particles. The removal efficiency equation considers the size distribution of particles, and the scour velocity equation is based on the Rouse equation. The removal efficiency equation yields the minimum particle size completely removed by the sedimentation tank. Using these equations the design equations have been obtained for the length and width of the settling tank. Besides other parameters, the design equations involve the completely removed minimum particle size, the specific gravity of the sediment particles, and the kinematic viscosity of water. These equations will be useful for the design of grit chambers and settling basins undergoing class-I settling.

关键词： DESTRUCTION REMOVAL EFFICIENCY PARTICLE DISTRIBUTION Viscosity design process overflow rate Sedimentation tanks design theory Kinematic viscosity Settling tanks Particle Size size distribution design equation Grit chambers Settling basins

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HETEROGENEITY OF STIMULATED DOPAMINE overflow WITHIN RAT STRIATUM AS OBSERVED WITH INVIVO VOLTAMMETRY

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BRAIN RESEARCH 1989年第2期487卷 311-320页

作者： MAY, LJ WIGHTMAN, RM INDIANA UNIV DEPT CHEM BLOOMINGTON IN 47405 USA

overflow of dopamine has been measured in the striatum of anesthetized rats with 60-Hz, 300-.mu.A electrical stimulations of the medial forebrain bundle. Electrodes were placed in the region of the caudate-putamen or the nucleus accumbens. The elliptical electrodes were fabricated from carbon fibers and had a major radius of 35 .mu.m. overflow was detected with fast-scan voltammetry repeated at 100-ms intervals. In both brain regions the detected substance had the voltammetric properties of dopamine. Measurements were made at different vertical electrode positions, varied by 100-.mu.m intervals. Significant differences in stimulated overflow were observed between each position in both brain regions. The dimensions over which overflow was observed compare to that of previous descriptions of the patch and matrix topology of the striatum. When the electrode was moved in 10-.mu.m intervals the variance was considerably less. The observed rate of overflow during stimulation exactly correlated with the maximal amount of dopamine observed during a stimulation. In addition, the overflow rate and the disappearance rate also correlated. This suggests that in both brain regions uptake and release sites are anatomically close to one another. The major difference between overflow curves measured in the two different regions was the appearance of an apparent mass transfer barrier to the electrode in the caudate-putamen.

关键词： Dopamine In vivo voltammetry Uptake rate overflow rate Striatum

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Bootstrap approximations for Bayesian analysis of Geo/G/1 discrete-time queueing models

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JOURNAL OF STATISTICAL PLANNING AND INFERENCE 2004年第1-2期120卷 65-84页

作者： Conti, PL Univ Roma La Sapienza Dipartimento Stat Probabilita & Stat Applicate I-00185 Rome Italy

In this paper we consider a Bayesian nonparametric approach to the analysis of discrete-time queueing models. The main motivation consists in applications to telecommunications, and in particular to asynchronous transfer mode (ATM) systems. Attention is focused on the posterior distribution of the overflow rate. Since the exact distribution of such a quantity is not available in a closed form, an approximation based on "proper" Bayesian bootstrap is proposed, and its properties are studied. Some possible alternatives to proper Bayesian bootstrap are also discussed. Finally, an application to real data is provided. (C) 2002 Elsevier B.V. All rights reserved.

关键词： nonparametrics overflow rate Geo/G/1 models waiting time distribution bayesian bootstrap asymptotics

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Mit :: Lcs :: Tr :: Mit-Lcs-Tr-721

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2016年

Mit :: Lcs :: Tr :: Mit-Lcs-Tr-721 by published by

关键词： flow control load balancing message messages mit-lcs-tr-721 model network node queue overflow overflow rate overflows processor processors queue queue overflow queue overflows queue size queue sizes service time waiting time workload

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Technical note

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International Journal of Environmental Studies 1996年第2期51卷 147-158页

作者： T. Viraraghavan W. Yeung S. Burland Faculty of Engineering University of Regina Regina Saskatchewan Canada Faculty of Engineering University of Regina Regina Saskatchewan Canada Faculty of Engineering University of Regina Regina Saskatchewan Canada

An analysis of the performance of primary clarifiers at the Regina Wastewater Treatment Plant was undertaken based on the average monthly operational data from 1981 to 1990. Removal efficiencies of suspended solids (SS) and biochemical oxygen demand (BOD) in the wastewater were related to surface overflow rate of clarifiers and influent concentration of SS and BOD respectively in a mathematical model.

关键词： Clarifier Wastewater treatment overflow rate suspended solids BOD

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基于FLUENT旋流式水力截流弃流切换井设计模拟

基于FLUENT旋流式水力截流弃流切换井设计模拟

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作者：张婧重庆大学

学位级别：硕士

近年来,国家投入了大量的人力物力治理滇池水污染,虽然滇池水环境有所改善,但是仍有诸多问题存在。目前为止,“九五”、“十五”以及“十一五”期间修建的截污治污体系已经初见成效,其范围包括源头的污染控制和末端的拦污系统,在整个系... 详细信息

近年来,国家投入了大量的人力物力治理滇池水污染,虽然滇池水环境有所改善,但是仍有诸多问题存在。目前为止,“九五”、“十五”以及“十一五”期间修建的截污治污体系已经初见成效,其范围包括源头的污染控制和末端的拦污系统,在整个系统框架中初期雨水干管的雨水在接入干渠之前为了防止干渠不产生倒灌和大面积溢流以及减少截流雨水中的有机颗粒物和泥砂对干渠产生的淤积,对雨水干管中的雨水在接入干渠之前进行沉砂处理和选择适当控制方式弃流显得至关重要。为了防止干渠的倒灌溢流和淤积,本课题设计研发了旋流式水力控制截流弃流切换井系统,根据干渠的水量来控制切换井的截流与弃流。采用三维设计软件SOLIDWORKS及模拟软件FLUENT对切换井模型进行构建和固液两相流模拟,得出了最优基本池型,并在关阀条件下进一步对最优基本池型进行优化,研究了颗粒直径、进水流速、溢流管高度、颗粒平均停留时间、溢流管角度、池体径深比与颗粒去除率的关系,最终得出最优化的池型结构和相应工况下的切换井最佳运行条件参数。同时对现场进行实际勘测,并选取了干渠合适采样点进行水质水量检测,筛选出部分实测结果用于切换井模拟的参数设置。对基本池型的模拟主要得出以下结论:①在所模拟的进水流速中,池型一在进水流速为1m/s、2m/s、4m/s、5m/s时有溢流情况,池型二在进水流速为2m/s、4m/s、5m/s时有溢流情况,池型三在进水流速为4m/s、5m/s时有溢流情况发生。②基本池型的颗粒运动轨迹都为螺旋旋流状,较为规律,颗粒旋流性较好。且随着颗粒直径的增大,有越多的颗粒被抛向池体壁面,壁面颗粒的停留时间较短,而池体内部的旋流颗粒停留时间则较长。当进水速度很大时,颗粒下沉性不好,在砂斗中多为悬浮状态。③在所模拟的几种直径颗粒中,对于除了1um之外的颗粒,池型三的去除率都相对较高,而池型一的去除率都相对较低,但总体相差不大。在进水速度相同的情况下,池型一的溢流率最高(除去没有溢流的情况),在同一种池型下,溢流率随着进水速度的增大而增大。综合以上分析选用基本池型二作为最优化基本池型。对基本池型二在关阀条件下模拟主要得出以下结论:①在关阀条件下,基本池型二在不同进水管和溢流管角度下的切换井颗粒运动轨迹都呈螺旋旋流状,在进水流速小于等于2m/s时,进入池体中的颗粒先向下旋流然后再向上旋流,最终大部分颗粒由溢流管流出,在进水流速大于2m/s时,颗粒分为上旋流和下旋流,其中下旋流还要继续上旋,最终颗粒也大部分由溢流管流出。90度角切换井中颗粒旋流性最好,颗粒轨迹均匀,砂斗中颗粒的停留时间明显比没有关阀时要长,下沉性较好。60度和150度角切换井中的颗粒旋流性较好,运动轨迹较为均匀,而120度切换井中的颗粒运动轨迹较无规律,且不均匀。砂斗中颗粒运动轨迹都较为规律,沿砂斗呈椭圆螺旋状运动,但250um的颗粒在砂斗中的下沉性不好,多数停留在砂斗中上部。②对于基本池型二在90度溢流角度(原基本池型二溢流角度)下,除了1um之外的颗粒在不同进水速度下关阀条件时的颗粒去除率都要高于不关阀条件。③池型二在关阀条件下按不同溢流角度颗粒去除率从大到小依次为90度、150度、60度、120度,除了极个别情况。按不同池体径深比颗粒去除率从大到小依次为:1.2、0.9、0.6。④颗粒平均停留时间与颗粒直径大小和进水流速有关,而颗粒去除率与颗粒停留时间之间没有特定的相关性规律,颗粒停留时间不是其主要影响因素。对于任何工况条件下,主要有以下结论:①在任何工况条件下1um的颗粒去除率都很低,基本在10%左右。②在不同工况条件下颗粒去除率在百分之几到百分之四十几之间且都遵循以下趋势:在进水流速相同的情况下,颗粒去除率都随着颗粒直径的增大而增大。对于除1um之外的颗粒来说,在颗粒直径相同的情况下,颗粒去除率都随着进水流速的增大呈现先增大后减小的趋势,在一定范围的进水流速下能达到较好的颗粒去除率,且都在进水速度为2m/s时达到最佳颗粒去除率。③颗粒直径、进水流速、溢流管高度、进水管和溢流管角度、池体径深比都能在一定程度上影响颗粒的去除率,其中溢流管高度对去除率的影响跟溢流情况和进水流速有关,且溢流管高度对颗粒去除率的影响较小。各种工况的最佳运行条件参数可以参照具体表中数据。综合以上分析得出基本池型二为最优化的基本池型,其在关阀条件溢流角度为90度、150度时,径深比为1.2或0.9时,50um和250um颗粒在进水速度为2m/s时能达到较好的颗粒去除率。

关键词： Dianchi Lake the vortex hydraulic well of switching the intercepting and abandon flow fluent software particle removal rate overflow rate

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