科创中国

声学多普勒水流剖面仪是目前较先进的河道测流设备.按《规范》要求,利用该仪器前,需要对该仪器与流速仪测流的实测流量进行对比实验,计算其换算系数.在分析ADCP测流原理的基础上,利用引黄干渠张二庄水文站实测流量资料,对两种测流方法测量结果进行对比分析.根据最小二乘法原理,建立回归直线,并对其进行检验.对回归直线进行拟合优度检验,拟合优度系数为0.982;对回归直线用F检验法进行截距检验,回归效果显著.在该断面用ADCP测流时,流量换算系数为0.9911.

The existing research on improving the hydraulic performance of centrifugal pumps mainly focuses on the design method and the parameter optimization.The traditional design method for centrifugal impellers relies more on experience of engineers that typically only satisfies the continuity equation of the fluid.In this study,on the basis of the direct and inverse iteration design method which simultaneously solves the continuity and motion equations of the fluid and shapes the blade geometry by controlling the wrap angle,three centrifugal pump impellers are designed by altering blade wrap angles while keeping other parameters constant.The three-dimensional flow fields in three centrifugal pumps are numerically simulated,and the simulation results illustrate that the blade with larger wrap angle has more powerful control ability on the flow pattern in impeller.The three pumps have nearly the same pressure distributions at the small flow rate,but the pressure gradient increase in the pump with the largest wrap angle is smoother than the other two pumps at the design and large flow rates.The pump head and efficiency are also influenced by the blade wrap angle.The highest head and efficiency are also observed for the largest angle.An experiment rig is designed and built to test the performance of the pump with the largest wrap angle.The test results show that the wide space of its efficiency area and the stability of its operation ensure the excellent performance of the design method and verify the numerical analysis.The analysis on influence of the blade wrap angle for centrifugal pump performance in this paper can be beneficial to the optimization design of the centrifugal pump.

糯扎渡水电站地处狭谷地区,泄洪最大水头182 m,溢洪道最大泄洪流量31318 m3/s,泄洪功率达55 860MW,其规模为目前国内最大,泄洪消能问题十分突出.为此,在可研阶段对泄洪建筑物布置进行了多方案比选研究,在招标阶段进行了深化研究,结合整体水工模型试验及溢洪道单体、掺气减蚀、护岸不护底、泄洪雾化等专题研究,设计了适合该工程的大型岸边溢洪道,在溢洪道挑流鼻坎下游设置消力塘,有效解决了消能问题.

Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants.More accurate models on the operating mechanism of the seals are needed to help improve their performance.The thermal fluid–solid interaction(TFSI)mechanism of the hydrostatic seal is investigated in this study.Numerical models of the flow field and seal assembly are developed.Based on the mechanism for the continuity condition of the physical quantities at the fluid–solid interface,an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method.Dynamic mesh technology is adopted to adapt to the changing boundary shape.Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure.The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data.Using the TFSI model,the behavior of the seal is presented,including mechanical and thermal deformation,and the temperature field.The influences of the rotating speed and differential pressure of the sealing device on the temperature field,which occur widely in the actual use of the seal,are studied.This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals,and the model is validated by full-sized experiments.

Most of current running quadruped robots have similar construction: a stiff body and four compliant legs. Many researches have indicated that the stiff body without spine motion is a main factor in limitation of robots' mobility. Therefore, investigating spine motion is very important to build robots with better mobility. A planar quadruped robot is designed based on cheetahs' morphology. There is a spinal driving joint in the body of the robot. When the spinal driving joint acts, the robot has spine motion; otherwise, the robot has not spine motion. Six group prototype experiments with the robot are carried out to study the effect of spine motion on mobility. In each group, there are two comparative experiments: the spinal driving joint acts in one experiment but does not in the other experiment. The results of the prototype experiments indicate that the average speeds of the robot with spine motion are 8.7%–15.9% larger than those of the robot without spine motion. Furthermore, a simplified sagittal plane model of quadruped mammals is introduced. The simplified model also has a spinal driving joint. Using a similar process as the prototype experiments, six group simulation experiments with the simplified model are conducted. The results of the simulation experiments show that the maximum rear leg horizontal thrusts of the simplified mode with spine motion are 68.2%–71.3% larger than those of the simplified mode without spine motion. Hence, it is found that spine motion can increase the average running speed and the intrinsic reason of speed increase is the improvement of the maximum rear leg horizontal thrust.

系统阐述了数据包络分析(DEA)的基本思想及其改进模型,在此基础上利用所构建的投入产出指标体系实证比较研究了2010年北京市、河南省、吉林省、江西省、山东省、福建省、宁夏回族自治区七大区域的物流效率,结论表明各区域效率由高至低依次为北京市、宁夏回族自治区、山东省、河南省、江西省、福建省、吉林省,其中北京和宁夏属于DEA有效,而这一结果具有较高的一致性与可靠性.

The current design of hydro-viscous clutch(HVC)in tracked vehicle fan transmission mainly focuses on high-speed and high power.However,the fluid torque under the influence of fluid temperature can not be predicted accurately by conventional mathematical model or experimental research.In order to validate the fluid torque of HVC by taking the viscosity-temperature characteristic of fluid into account,the test rig is designed.The outlet oil temperature is measured and fitted with different rotation speed,oil film thickness,oil flow rate,and inlet oil temperature.Meanwhile,the film torque can be obtained.Based on Navier-Stokes equations and the continuity equation,the mathematical model of fluid torque is proposed in cylindrical coordinate.Iterative method is employed to solve the equations.The radial and tangential speed distribution,radial pressure distribution and theoretical flow rate are determined and analyzed.The models of equivalent radius and fluid torque of friction pairs are introduced.The experimental and theoretical results indicate that tangential speed distribution is mainly determined by the relative rotating speed between the friction plate and the separator disc.However,the radial speed distribution and pressure distribution are dominated by pressure difference at the lower rotating speed.The oil film fills the clearance and the film torque increases with increasing rotating speed.However,when the speed reaches a certain value,the centrifugal force will play an important role on the fluid distribution.The pressure is negative at the outer radius when inlet flow rate is less than theoretical flow,so the film starts to shrink which decreases the film torque sharply.The theoretical fluid torque has good agreement with the experimental data.This research proposes a new fluid torque mathematical model which may predict the film torque under the influence of temperature more accurately.

Three dimensional(3D)displacements,which can be translated further into 3D strain,are key parameters for design,manufacturing and quality control.Using different optical setups,phase-shift methods,and algorithms,several different 3D electronic speckle pattern interferometry(ESPI)systems for displacement and strain measurements have been achieved and commercialized.This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement.After an overview of the fundamentals of ESPI theory,temporal phase-shift,and spatial phase-shift techniques,3D deformation measurements by the temporal phase-shift ESPI system,which is suited well for static measurement,and by the spatial phase-shift ESPI system,which is particularly useful for dynamic measurement,are discussed.For each method,the basic theory,a brief derivation and different optical layouts are presented.The state of art application,potential and limitation of the ESPI systems are shown and demonstrated.

通过对中关图书馆评估机构、统计工作及评估指标体系的介绍与比较研究,指出我国图书馆绩效评估存在的主要问题.运用案例分析方法,详细对比中关大学图书馆绩效评价体系,分析我国图工委图书馆绩效评估体系存在的不足,提出改进我国图书馆绩效评估的建议.

The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m3(DSL-2329) plays an important role in the quality control for silicon single crystal manufacturing. A new method is developed based on hydrostatic suspension principle in order to determine the two coefficients with high measurement accuracy. Two silicon single crystal samples with known density are immersed into a sealed vessel full of DSL-2329. The density of liquid is adjusted with varying liquid temperature and static pressure, so that the hydrostatic suspension of two silicon single crystal samples is achieved. The compression and thermal expansion coefficients are then calculated by using the data of temperature and static pressure at the suspension state. One silicon single crystal sample can be suspended at different state, as long as the liquid temperature and static pressure function linearly according to a certain mathematical relationship. A hydrostatic suspension experimental system is devised with the maximal temperature control error ±50 μK; Silicon single crystal samples can be suspended by adapting the pressure following the PID method. By using the method based on hydrostatic suspension principle, the two key coefficients can be measured at the same time, and measurement precision can be improved due to avoiding the influence of liquid surface tension. This method was further validated experimentally, where the mixture of 1, 2, 3-tribromopropane and 1,2-dibromoethane is used as DSL-2329. The compressibility and thermal expansion coefficients were measured, as 8.5′10–4 K–1 and 5.4′10–10 Pa–1, respectively.