拉瓦尔喷管喉部区域当量直径液力测量方法

拉瓦尔喷管喉径尺寸要求严格,现有成熟的深孔测量方法无法直接应用于拉瓦尔喷管喉部区域当量直径测量。在分析拉瓦尔喷管喉部区域当量直径液力测量的孔口流动模型基础上,提出了基于芯型测头塞规法的拉瓦尔喷管喉部区域当量直径液力测量方法,分析了芯型测头塞规尺寸与孔口流动模型及其相对灵敏度的关系。优选了短孔模型作为拉瓦尔喷管喉部区域当量直径液力测量的基本模型,确定了当量直径液力测量参数,研制了当量直径液力测量原型装置。在该装置上进行了测量试验,分析了芯型测头塞规直径和测量压差对喉部区域过流流量的影响。最终的重复性试验结果表明,该方法的测量重复性误差为±0.001 8 mm,能够满足拉瓦尔喷管喉部区域当量直径测量需要。

高速铁路路基表面沉降测量方法研究

为研究高速铁路路基表面沉降测量方法,本文依托实际工程,以沉降变形传感技术为基础,介绍了一种基于液力测量原理的高速铁路路基表面沉降自动测量传感技术。重点研究了高速公路路基表面沉降自动测量系统,提出了以自动测量系统为主,人工测量为辅的沉降测量方案,并在实际工程中进行了应用。研究表明基于液力测量原理的沉降自动测量传感技术在高速铁路路基表面沉降测量中具有很大的可靠性和实用性。

Implementation of Vibrancy Awaking Pressure Measuring Instrument for Single Hydraulic Prop

An instnmaent awakened by means of vibration for single hydraulic prop pressame measuring is described in this paper. The principle and implementation of this metlmd are introduced in detail. The instnznent uses the hgh-perftmnance single chip C8051F310 as its MCU and vibration sensor as its awaking device. It has such advantages as small vohane and low power consmnption, and moreover it could resolve the problem that traditional pressure measming instrument on single hydraulic prop can＇t be used in coal mine.

Vapor Pressure Measurement and Correlation of 2-Methyl-Butanol Acetate Containing Calcium Chloride

The CaCl2 solubility in 2-methyl-butanol acetate and the vapor pressure of 2-methyl-butanol acetate containing CaCl2 were measured in the range of 90-135°C and from very low salt concentration to saturation.The experimental data were correlated with two equations,a modified Antoine equation with the dissolved salt taken into account and a nonrandom two liquid-electrolyte（e-NRTL）model.Both models are in good agreement with the experimental data.This study provides essential physical data for further investigation of vapor-liquid equilibrium system containing salt.

Vapor pressure measurement and correlation of acetonitrile + 1-butyl-3-methylimidazolium chloride, + 1-butyl-3-methylimidazolium tetrafluoroborate, and + 1-hexyl-3-methylimidazolium chloride

Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate([C4mim][BF4])and+1-hexyl-3-methylimidazolium chloride([C6mim][Cl])at temperatures of 313 to 353 K by a quasi-static method.The experimental data for the binary systems were correlated by the non-random two liquid(NRTL)equation with an average absolute relative deviation(AARD)of within 1.84%.The results indicate that the three ionic liquids(ILs)can result in a negative deviation from the Raoult's law for the binary solutions containing acetonitrile,and the affinity between ILs and acetonitrile molecules follows the order[C4mim][BF4]+acetonitrile N[C4mim][Cl]+acetonitrile N[C6mim][Cl]+acetonitrile.

Slide stability of hydraulic structures on subbed soil

The study on slide stability of hydraulic structures on subbed soil was made. Using the slide test results of dragged concreting base plates on subbed soil pits, the decreased value of bearing capacity on slide after re- bound and repression influence of subbed soil was determined, and the envelope of ultimate slide shear resistance was also quantitatively determined. Due to the lack of similar mechanisms of slide stability on subbed soil and base plate of hydraulic structures, different safety coefficients for the slide stability were adopted. It was suggested to use the maximum compressive stress O＇m~ of eccentric load to predict structure displacement, slide and creepy slippage of subbed soil, to determine the sliding creepy contour and limit the maximum load on subbed soil. Two hydraulic structures that had been put into operation were reviewed by this method, and the results accorded with the real conditions.

Metal Working Fluids Based on Vegetable Oils for Grinding Operations

The work described in this paper is part of the European Project IBIOLAB, trying to find suitable metalworking fluids based on vegetable oils, such us High Oleic Sunflower Oil （HOSO）. In this paper, the performance of the newly developed IBIOLAB water based formulations supplied by SOGELUB and LUBRIX is analyzed and compared with reference Mineral and Synthetic cutting fluids Innovative characterization tests at laboratory scale （3 ball abrasion tests, grinding simulation tests, Tapping torque test） in real grinding machines in combination with advanced characterization techniques （residual stress measurements monitored by RX to predict formation of cracks）, have been used for screening the performance of the emulsions.

Study on Shock Wave and Turbulent Boundary Layer Interactions in a Square Duct at Mach 2 and 4

In this paper, the outline of the Mach 4 supersonic wind tunnel for the investigation of the supersonic internal flows in ducts was firstly described. Secondly, the location, structure and characteristics of the Mach 2 and Mach 4 pseudo-shock waves in a square duct were investigated by color schlieren photographs and duct wall pressure fluctuation measurements. Finally, the wall shear stress distributions on the side, top and bottom walls of the square duct with the Mach 4 pseudo-shock wave were investigated qualitatively by the shear stress-sensitive liquid crystal visualization method. The side wall boundary layer separation region under the first shock is narrow near the top wall, while the side wall boundary layer separation region under the first shock is very wide near the bottom wall.

Mandatory criteria for the application of variability-based parameters of fluid responsiveness: a prospective study in different groups of ICU patients

Background and objective： Stroke volume variation（SVV） has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm（SR） and controlled mechanical ventilation（CV） are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit（ICU） patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of Pi CCO-monitoring（primary endpoint） and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis. Methods： The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients. Results： In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent： the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter（36.1% vs. 21.9%; P0.001）. Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis. Conclusions： The applicability of SVV in a predominantly medical ICU is only about 25%–35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.