A weighted mean velocity feedback strategy in intelligent two-route traffic systems

Information feedback strategies can influence the traffic efficiency of intelligent traffic systems greatly.Based on the more practical symmetrical two-route scenario with one entrance and one exit,an improved weighted mean velocity feedback strategy（WMVFS） is proposed,which is not sensitive to the precision of global position system（GPS） devices.The applicability of WMVFS to different weight factors,aggressive probabilities,densities of dynamic vehicles,and different two-route scenarios（symmetrical scenario and asymmetrical scenario with a speed limit bottleneck） is analyzed.Results show that WMVFS achieves the best performance compared with three other information feedback strategies when considering the traffic flux and stability.

An analytical model for the prediction of cross-section profile and mean roll radius in alloy bar rolling

In a round-oval-round pass rolling sequence, the cross-section profile of an outgoing workpiece was predicted first after getting the maximum spread. The concept ＂critical point on the contact boundary＂ was proposed and the coordinates of the critical point were solved. The equivalent contact section area was represented and the mean roll radius was determined. The validity of this model was examined by alloy bar rolling experiment and rigid-plastic FEM simulation. Compared with the existing models, the mean roll radius obtained by this model is similar to experiment data.

A New Model for Prediction of Mean Liquid Circulating Velocity in Bubble Columns

A new model without any fitting parameter for estimating the mean liquid recirculating velocity has been derived from previous work directly. The prediction agrees with experimental data reasonably well. Accurency of prediction from the new model is comparable with the models reported in the literature. However, the new model has a potential capability to predict the average liquid recirculation velocity at elevated pressure bubble columns since n and c is developed under pressure. However this needs to be further tested experimentally.

Observations and analyses of floc size and floc settling velocity in coastal salt marsh of Luoyuan Bay, Fujian Province, China

In coastal environments, fine-grain sediments often aggregate into large and porous flocs. ElectroMagnetic Current Meters （EMCM） and Laser In Situ Scattering and Transmissometry （LISST-ST） have been deployed within a Spartina alterniflora marsh of the Luoyuan Bay in Fujian Province, China, to measure the current velocity, the floc size and the settling velocity between 15 and 22 January 2008. During the observations, the near-bed water was collected in order to obtain the suspended sediment concentration （SSC） and constituent grain size. Data show that： （1） the nearbed current velocities vary from 0.1 to 5.6 cm/s in the central Spartina alterniflora marsh and 0.1–12.5 cm/s at the edge; （2） the SSCs vary from 47 to 188 mg/dm 3 . The mean grain size of constituent grains varies from 7.0 to 9.6 μm, and the mean floc sizes （MFS） vary from 30.4 to 69.4 μm. The relationship between the mean floc size and settling velocity can be described as： w s =ad b , in which w s is the floc settling velocity （mm/s）, a and b are coefficients. The floc settling velocity varies from 0.17 to 0.32 mm/s, with a mean value of 0.26 mm/s, and the floc settling velocity during the flood tide is higher than that during the ebb tide. The current velocity and the SSC are the main factors controlling the flocculation processes and the floc settling velocity.

Comparative studies on the hot corrosion behavior of air plasma spray and high velocity oxygen fuel coated Co-based L605 superalloys in a gas turbine environment

An improvement in the corrosion resistance of alloys at elevated temperature is a factor for their potential use in gas turbines. In this study, Co Ni Cr Al Y has been coated on the L605 alloy using air plasma spray(APS) and high-velocity oxygen fuel(HVOF) coating techniques to enhance its corrosion resistance. Hot corrosion studies were conducted on uncoated and coated samples in a molten salt environment at 850°C under cyclic conditions. Thermogravimetric analysis was used to determine the corrosion kinetics. The samples were subjected to scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction for further investigation. In coated samples, the formation of Al2O3 and Cr2O3 in the coating acts as a diffusion barrier that could resists the inward movement of the corrosive species present in the molten salt. Coated samples showed very less spallation, lower weight gain, less porosity, and internal oxidation as compared to uncoated sample.HVOF-coated sample showed greater corrosion resistance and inferred that this is the best technique under these conditions.

Feasibility of the 2-point method to determine the load-velocity relationship variables during the countermovement jump exercise

Purpose:This study aimed to examine the reliability and validity of load-velocity(L-V)relationship variables obtained through the 2-point method using different load combinations and velocity variables.Methods:Twenty men performed 2 identical sessions consisting of 2 countermovement jumps against 4 external loads(20 kg,40 kg,60 kg,and80 kg)and a heavy squat against a load linked to a mean velocity(MV)of 0.55 m/s(load_(0.55)).The L-V relationship variables(load-axis intercept(L_(0)),velocity-axis intercept(v_(0)),and area under the L-V relationship line(A_(line)))were obtained using 3 velocity variables(MV,mean propulsive velocity(MPV),and peak velocity)by the multiple-point method including(20-40-60-80-load_(0.55))and excluding(20-40-60-80)the heavy squat,as well as from their respective 2-point methods(20-load_(0.55)and 20-80).Results:The L-V relationship variables were obtained with an acceptable reliability(coefncient of variation(CV)≤7.30%;intra-class correlation coefficient>0.63).The reliability of L_(0)and v_(0)was comparable for both methods(CV_(ratio)(calculated as higher value/lower value):1.11-1.12),but the multiple-point method provided Al_(ine)with a greater reliability(CV_(ratio)=1.26).The use of a heavy squat provided the L-V relationship variables with a comparable or higher reliability than the use of a heavy countermovement jump load(CV_(ratio):1.06-1.19).The peak velocity provided the load-velocity relationship variables with the greatest reliability(CV_(ratio):1.15-1.86)followed by the MV(CV_(ratio):1.07-1.18),and finally the MPV.The 2-point methods only revealed an acceptable validity for the MV and MPV(effect size≤0.19;Pearson s product-moment correlation coefficient≥0.96;Lin's concordance correlation coefficient≥0.94).Conclusion:The 2-point method obtained from a heavy squat load and MV or MPV is a quick,safe,and reliable procedure to evaluate the lower-body maximal neuromuscular capacities through the L-V relationship.

A model for the mean velocity of debris flow movement based on the minimum energy dissipation principle

The geomorphic minimum energy dissipation principle is important in the development of gully evolutionary theory.The impact of debris flows on channels during movement also adheres to this theory.A minimum energy dissipation model for debris flows has been obtained from previous studies,which is derived from the flow rules of runoff along a channel under rainfall or ice-snow meltwater conditions.However,the lack of consideration for erosion characteristics has hindered a comprehensive understanding of the movement characteristics of debris flow.In this paper,the phenomenon of volume increase resulting from the entrainment along debris flow movement is considered in order to derive a model for the mean velocity,reflecting the minimum energy dissipation principle.The entire expression of the mean velocity model is determined through 38 typical glacial and rainstorm debris flow cases.To evaluate the reliability of the proposed model,we employed 164 monitoring data from 1995 to 2000 in the Jiangjia gully,Yunnan,China.The results show that the velocity calculated by the proposed model are highly correlated with those obtained from the monitoring data.Additionally,a comparison is made between the mean velocities calculated by the proposed model and those obtained from previous studies,highlighting the exceptional applicability of the proposed model.This study will contribute to reveal the movement laws of debris flow along the channel.

基于改进K-means的潜油电泵质量评估方法研究

针对潜油电泵使用寿命的问题,开展了基于潜油电泵井下振动测量的单节潜油电泵装配质量等级分类的研究,建立了单节潜油电泵的三维振动模型,提出了拐点法优化K-means聚类算法初始点的选取,采用三维合成方法求取电泵三个维度的合成振动加速度均方根值,利用改进K-means算法对239节潜油电泵的合成振动加速度均方根进行了聚类分析,建立了潜油电泵装配质量等级评价标准。对所测量的电泵进行质量跟踪,其结果验证了电泵装配质量等级分类的合理性。结果表明,潜油电泵合成振动加速度均方根小于1.30 m/s^2的潜油电泵为优质电泵,使用寿命最长,宜用于高产井;处于1.30~1.72 m/s^2的为质量良好电泵,使用寿命较长,可正常使用;处于1.72~2.35 m/s^2的为质量合格电泵,使用寿命一般,应谨慎使用;大于2.35 m/s^2为质量较差电泵,使用寿命较短,应维修后再使用。

K-Means++的声速剖面精简方法

在深海定位中,声线传播距离长、声速剖面层数多,采用常梯度声线跟踪虽然提高了定位精度,但明显降低了定位的计算效率。针对这一问题,本文引入优化聚类算法,提出了一种基于K-Means++的声速剖面精简方法。该方法将原始声速剖面的梯度分为正负2个部分,采用K-Means++对每部分进行初始聚类,再对聚类后的每一簇进行不同类别数的K-Means++聚类,将相邻相同类的层合并后得到精简声速剖面。采用精简声速剖面进行水下定位,并与原始声速剖面定位效果对比。实验结果表明:本文方法在确保原始声速剖面空间结构和水下定位精度的前提下,显著提高了定位计算效率,且在不同深度的定位精度与原始声速剖面定位精度保持一致。

Flow Field Around Rushton Turbine in Stirred Tank by Particle Image Velocimetry Measurement

In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns were studied. One was that the impeller runs at constant speed, the other was that the impellerruns at time-dependent speed and in a periodic way. The emphasis of the paper was on the comparison of meanand RMS velocity vector maps and profiles between these two types of motion patterns, and especial attention waspaid to the comparison of the mean velocity, time-averaged RMS velocity, phase averaged RMS velocity betweenthe constant 3 RPS (revolution per second) and time-dependent operation. The Reynolds number was between 763and 1527. The study explained the mechanism that time-dependent RPS is more efficient for mixing than that ofconstant RPS.

Investigation on Eccentric Agitation in the Stirred Vessel Using 3D-Laser Doppler Velocimeter

The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-maining approximately constant. The experimental results were provided such as the mean velocity field, fluctuat-ing velocities, turbulent kinetic energy, Reynolds shear stress and time series of the velocity in the stirred tank. These results probably provided the valuable basis to further optimize and enlarge the stirred tank in the industrial process.

基于Voronoi图和改进K-means的扇区优化研究

扇区划分是空中交通管制的一项重要工作,合理的扇区划分能够提高空域的使用率,保障航空器的飞行安全。鉴于平峰时段的扇区划设不能很好适用于复杂空情的现状,提出一种基于Voronoi图和改进K-means的扇区优化方法。依据空情态势构建冲突网络,结合航空器速度障碍关系和复杂网络理论提出了扇区综合管制负荷计量方式。依据负荷值采用改进K-means聚类方法确定了合理的聚类中心作为Voronoi图的生成元,从而使用Voronoi图的划分方法生成合理边界来优化扇区。采集厦门空域管制扇区数据作为仿真场景进行了计算分析,结果表明,在繁忙时段,优化后的扇区管制负荷平均方差相比原扇区降低了66.04%,平峰时段降低了13.88%,达到了均衡扇区负荷的目的,验证了扇区优化方法的有效性,为现有的扇区划设工作提供了参考依据。

基于改进K-means聚类的惯性行人导航零速检测算法

行人导航中不同运动状态下零速区间的运动数据也有所不同,这就要求零速检测算法具有良好的适应性。针对利用阈值实现零速检测的算法在多种运动状态下适应性差的问题,该文提出了一种基于改进K-means聚类的零速检测算法(zero-velocity interval detection algorithm based on improved K-means clustering, IKC)。首先,在运动的开始阶段,通过K-means聚类对角速度数据进行聚类,从而得到零速区间与非零速区间的中心点;然后根据设定的数据点到中心点的距离条件对零速区间与非零速区间进行划分,相比于其他算法,优化了数据处理过程,有效缩短了计算时间,并且不依赖阈值条件,有效提高了该算法的适应性;同时,根据零速区间与非零速区间的持续时间判断运动状态是否改变,若发生改变则重新进行K-means聚类获取新运动状态的中心点。最后,在实际行人导航系统中对新提出的算法进行了实验验证,从计算量及行人导航精度等方面与步态特征提取的K均值聚类自适应判别算法(K-means clustering adaptive detection, KCA)、基于贝叶斯的自适应阈值零速检测算法(bayesian adaptive threshold detection, BAT)进行了对比分析。结果表明,本文提出的基于改进K-means聚类的零速检测算法不仅有效的减小了计算时间,而且具有较高的导航精度和导航稳定性。

基于平均声速测量的声速剖面实时重构方法

针对传统的声速剖面重构方法往往不具备实时性的问题,本文提出了一种基于平均声速测量的声速剖面实时重构方法。首先,基于历史数据进行特征分解并选择经验正交函数(Empirical Orthogonal Function, EOF)的阶次;其次,利用实测的水下某深度的声速和该深度至海面的平均声速,通过求二元一次方程组的最小范数解得到EOF重构系数;最后,结合历史声速剖面重构全海深声速剖面。使用西太平洋海域的再分析数据对该方法进行了仿真验证,结果表明:采用该方法重构的声速剖面与真实声速剖面拟合效果较好,平均均方根误差约为1.31 m·s-1。本文所提方法可为水下航行器实时重构声速剖面提供技术支撑。

The effect of suspension on mean velocity profile

The vertical gradient of suspended sediment concentration often exists in estuarine and coastal regions. The existence of such concentration gradient, particular that of cohesive suspended sediment concentration gradient, affects the flow velocity profile. Based on the wave-current full depth combined model, k-e turbulent model is employed in this paper to simulate the effect of sediment concentration on the wave-current flow. A quantitative analysis of change mechanism of mean velocity profile is presented. The results show that the change mechanism of Eulerian mean current velocity under clear water is different from that under sediment-water mixed flow.

基于全波形反演速度约束的叠后地震反演方法

对于井数较少或者沉积相变化较快的地层,利用测井曲线建立的反演低频模型难以控制反演弹性参数的空间变化趋势。据此笔者发展了基于FWI速度约束的叠后地震反演方法,该方法充分利用了FWI速度的真三维信息,据此得到反演弹性参数的空间变化趋势。对于叠后地震反演所需要的纵波阻抗低频模型,提出了基于测井岩石物理拟合关系将FWI速度转换为FWI纵波阻抗的方法。另外,针对FWI纵波阻抗和测井纵波阻抗存在一定差异的问题,提出了FWI纵波阻抗均值校正方法,据此可得到较为准确的纵波阻抗低频模型。单井和实际工区应用表明,纵波阻抗反演结果和井上结果匹配性较高,因此笔者提出的基于FWI速度约束的叠后地震反演方法较为有效,可为储层预测提供较为有利的技术支持。

面向粒子图像测速的光流金字塔插值优化方法

提出了一种面向粒子图像测速的光流金字塔插值优化方法,可以减小重建角度误差和均方根误差,尤其是图像边缘部分的角度误差。使用该优化算法分别对单涡流、双涡流、DNS湍流粒子场进行速度场重建,得到三种流场的均方根误差和平均角度误差比优化前至少降低了15.96%和19.87%。搭建二维PIV实验系统,在待测流场中均匀撒入100μm的PSP粒子,进行旋转实验和注水实验,分别模拟涡流场和射流场,所提出的优化算法可以获得与常见算法流形一致的速度场。

Estimations of the Maximum Tangential Velocity V_(θm) in the Vortex Core Region and also the Mean Rotational Velocity V_(oi) near the Concave Wall Surface in the Returned Flow Type Cyclone Dust Collector

There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collection efficiency, one of the most important factors is the maximum tangential velocity V0m in the vortex core region in the cyclone body. In order to determine V0~ by the simple method, it is useful to apply the mechanical balance of the angular momentum fluxes under the assumption of Ogawa combined vortex model which is composed of the quasi-forced vortex in the vortex core region and also the quasi-free vortex surrounded the vortex core region and also under the assumption of the introduction of equivalent length Heq corresponding to the cone spaces of the cyclone body and the dust bunker. On the other hand, the mean rotational velocity Voi near the concave wall surface is also estimated by the mechanical balance of angular momentum fluxes with the moment of viscous friction force. For confirming the general applications of the obtained equations, the returned flow types cyclones changed the throat diameter D3 are designed. The material of the cyclone is the transparent acrylic resin. Therefore the inner surface of the cyclone body can be regarded as smooth surface. The comparisons of the measured velocities V~ and Voi by a cylindrical Pitot tube are shown in good agreement with those of the proposed equations. The above stated results are described in detail.

Close Correlations Between Carotid Arterial Mean Blood Flow Velocity,Body Mass Index,and Temperature in Normal Individuals

Objective:Assessing carotid and radial pulses is an essential sphygmology method in traditional Chinese medicine(TCM).It is believed in TCM and by doctors that pulse force is markedly linked with the physiological state of a human,including body mass index(BMI)and temperature.However,comprehensive analysis elucidating these potential correlations remains undetermined.Therefore,this investigation aimed to assess the association of pulse strength with human metabolism.Materials and Methods:The mean blood flow velocity(MBFV)of the carotid artery and pulse force of 122 healthy adults included in this investigation were assessed using ultrasound and manual palpation.Their thermal texture map was also acquired.Results:No substantial variation was observed in the carotid arterial MBFV among normal individuals(P>0.05)regardless of body side and gender.However,young individuals had higher blood velocity than middle-aged individuals(P<0.05).Furthermore,it was identified that MBFV was negatively associated with BMI and torso temperature;however,it was positively linked with hand temperature.Conclusions:This investigation revealed that carotid arterial MBFV could indicate the physical state of humans,including BMI and temperature,and therefore,is valuable for elucidating the effect of TCM on yin–yang.The data validated some TCM beliefs and supported the implementation of sphygmology in TCM.