Tension measurement of 7.6 m drift tubes of the VENUS muon detector

A semiautomated tension measurement system was developed and constructed for 7.6 m long drift tubes of the VENUS detector at KEK. The system utilizes the wire vibration method and consists of a 400 G, 40 cm long dipole magnet and two CAMAC modules. The voltage and phase shift induced in an anode wire are measured to detect the resonance frequency of wire vibration when an alternating current is applied to the wire in a magnetic field. Eight wires in a module can be consecutively measured by a computer control. The reproducibility of data measured by the system was found to be excellent and the accuracy of the measurement was also found to be satisfactory. Tension data obtained for 800 wires of 70 μm in diameter have the mean value of 394.4 gw with the rms deviation of 7.2 gw for the intended wire tension of 400 gw.     

Cathode readout of limited streamer tubes with conductive plastic walls

The performance of cathode readout on the limited streamer drift tubes with conductive plastic wall was studied. Cathode strips were placed on the outside of tubes in parallel and perpendicular to the anode wires. It was found that conductive plastic walls broadened the induced charge distribution on the cathode strips perpendicular to the anode wire. Position resolution of 420–450 μm was obtained along the anode wire, and parallel strips were found to be useful to solve left-right ambiguities in the drift chamber readout.     

A simple method for measuring wire tension in drift tubes

Measuring the tension of wires in drift tubes after construction is an important procedure because sometimes the wires get loose after soldering. The method described here uses a simple circuit for observing the change in the Lissajous pattern of a wire resonating with an external magnetic field. The vibration of the wire causes a fundamental harmonic component in the current and results in a periodic change of the Lissajous pattern. Measurement of this fundamental harmonic signal provides a precise determination of the resonance frequency and the wire tension.     

水平双侧强化管传热性能测定的新方法及实验研究

针对水平双侧强化管的传热性能测定提出了一种新的方法,称之为水环实验法,其基本过程是:在自行设计的套管换热装置中,通过实验得到缠绕铜丝的光滑传热管管外环形小通道内单相水传热关联式,应用该式通过热阻分离的方法得到一种新齿形内螺纹双侧强化传热管的管内传热关联式。同时研究了对于该管水在管内对流和制冷工质R123在管外凝结的传热情况,并采用水环实验法和常规热阻分离法对实验数据进行处理。经过实验研究和理论分析表明:本文的方法所得到的管内外传热系数较常规热阻分离法更加准确。     

Front end electronics and cosmic ray tests of muon drift tubes for the SDC detector

A system of front end wire chamber electronics for a large scale array of muon drift tubes is described. Simulations of the tube performance with readout electronics are discussed and compared with cosmic ray measurements.     

Surface Tensions and Thermal Conductivities of Aqueous LiBr-Based Solutions Containing n-Octanol and 2-Ethyl-1-Hexanol: Application to an Absorption Heat Pump

Surface tensions and thermal conductivities were measured for LiBr+1,3-propanediol+water and LiBr+LiI+1,3-propanediol+water. These two mixtures were chosen as one of the potential candidates for working fluids for absorption heat pumps. Surface tensions and thermal conductivities were measured by the capillary rise method equipped with a cathetometer and the transient hot wire method with a coated tantalum wire, respectively. The measured surface tension and thermal conductivity data were well correlated with a simple polynomial function of temperature and absorbent concentration. In addition, the surface tensions of LiBr+1,3-propanediol+water containing a small amount of alcohol-based surfactants, n-octanol and 2-ethyl-1-hexanol, were also measured at 298.15 K by the ring method. An increase in the surfactant concentration up to about 500 ppm leads to a gradual decrease in the mixture surface tensions.     

Wire tensions and bending moments in axially loaded seven wire strand

Carefully instrumented tensile tests were performed on a straight single steel strand of seven-wire construction having core and helical wire diameters of 3–66 mm and 3–33 mm, respectively, and a lay angle of 14-6. Strain gauges in groups of three with their grid axes parallel and having a common backing were attached to all six helical wires at the mid-strand position. For loading within the linear range of the load-extension response (all tests) and load-rotation response (in tests with free and partial torsional restraint of the ends) the outputs from these strain gauges were used to compute wire tensions and bending moments. Strand extension, rotation and torque generated under axial load (fixed-end and partial torsional restraint) were also recorded.
Test results showed that the share of the total strand load taken by the helical wires decreased as the torsional restraint on the strand was reduced. The mean tension in the helical wires was found to be 27-5% smaller in the free-end tests than in fixed-end tests for a given strand load. Theoretical predictions underestimate this reduction in tension by up to 80%. Bending moments in the wires were found to be about 8% less than predicted in the fixed-end condition and over 20% smaller in the free-end condition.
As expected, the slope of the linear regions of the load-extension and load-rotation plots decreased as the torsional restraint was reduced. However, the rate of decrease in the case of load-extension plots was found to be less than predicted theoretically and the rotation measured was generally less than predicted theoretically. This is consistent with the helical wire tensions being smaller than the predicted values since the tangential components of these reduced tensions would have less effect in their unwrapping action on the strand under increasing axial load.     

High-current relativistic electron beam transport in a drift tube in the absence of an external magnetic field

The current of an intense relativistic electron beam emitted from a metal-dielectric multiedge cathode that passes through an anode grid and is transported in a smooth-wall drift tube in the absence of an external magnetic field has been measured at the collector. In these experiments, the electron flux was transported over a distance twice as large as the drift tube diameter. An optimum cathode and storage electrode configurations have been found that allowed the efficiency of the relativistic Cherenkov microwave oscillator without a guiding magnetic field to be increased up to 10% at a maximum output pulse radiation power of 1.3 GW and a working frequency of 4.03 GHz.     

Electrical Discharge Machining of MMCs Reinforced with Very Small Particles

This paper investigates material removal rate (MRR), kerf width, surface finish, and electrode wire wear for different pule-on-times as well as wire tensions during EDM of 6061 aluminum alloy reinforced with 10 vol % 700 nm SiCp MMC. Effects of pulse-on-time on output variables at lower and higher wire tensions were investigated. Similarly, effects of the wire tensions on output variables at shorter and longer pulse-on-times were also investigated. Longer pule-on-time increases the MRR though the higher wire tension reduces the MMR. The effect of wire tension on MRR is much more significant at longer pule-on-time compare to that at shorter pule-on-time. There is an optimum pule-on-time for which best surface finish is achieved. The surface finish deteriorates when the pulse-on-time is higher or lower than the optimum pule-on-time. With the rise of tension in wire, the surface roughness increases and decreases at shorter and longer pule-on-times, respectively. The machined surface contains solidified molten material, splash of materials, and blisters. Generation of the tapered slot with higher kerf width at the top indicates the wear of wire electrode. Significant variation of the electrode wire diameter was due to coating of the matrix, wear, and clogging of small reinforced particles in the electrode gap.     

A drift chamber with variable drift velocity

A wedge-type drift chamber is planned to be used as part of the inner detector of the DELPHI experiment at the large electron-positron (LEP) collider at CERN. The chamber features drift velocities (carefully controlled) proportional to the total drift distance to facilitate triggering. The gas choice and its consequencea for calibration with and without magnetic field are discussed. Long-term stability and the effect of a magnetic field have been measured with a prototype chamber. Most tests reported here have been done with a laser beam with single wire accuracies below 20 μm. The single wire accuracy for measuring minimum ionizing particles was found to be 80 μm.     

Press-Fit Sheathing for Ceramic Gun Liners

Ceramic materials are being investigated by the Army for use in gun tubes. Compared to gun steels, ceramics possess superior wear resistance at ballistic temperatures, thus enabling improved lifetime for gun tubes. In order to survive the ballistic event, however, it is necessary to prestress the ceramic components with external sheathing to offset the tensile stresses in the tube wall that occur during the ballistic event. Previous sheathing designs for ceramic liners have included thermal shrink fits of tubular metallic components, steel wire overwrapped under high tension, and advanced fibrous composites overwrapped under high tension. In the present investigation, press-fitted composite sheaths are fabricated and tested with the purpose of validating a computer model applicable to the design of ceramic gun barrel liners.     

Predicting the mechanical behaviour of Kevlar/epoxy and carbon/epoxy filament-wound tubes

The axial, hoop and shear moduli and failure conditions of carbon/epoxy and Kevlar/epoxy filament-wound tubes have been determined through respective applications of internal pressure, tension and torsion. The introduction in the laminated plate theory of a gradual reduction in individual moduli makes it possible to overcome the limitations of the theory and enables accurate predictions to be made of the linear and non-linear stress/strain curves of 90°/ ±0/90° tubes. The existence of a dominant layer in the failure of the multilayered tubes has been shown experimentally. When associated with a failure criterion applied to the dominant layer, the new model permits the prediction of tube failure. Agreement between calculated and experimental data is better than 5%.     

The mechanical properties of tubular solid oxide fuel cells

The mechanical strength of solid oxide fuel cell (SOFC) components is one of the key issues for determining their performance and reliability. A minimum strength is required for the handling of these components in manufacturing, namely in relation to the application of the electrode or electrolyte coatings, the application of the current collection metals and the construction of the stack. Small tubular SOFCs have been found to have excellent thermal shock properties and low-cost of fabrication through traditional extrusion techniques. The mechanical integrity of the small, thin walled, tubular ceramics could be tested using traditional 3 or 4-point bending techniques, however these techniques are liable to cause failure by crushing the tube wall. Thus, a more reliable method for realizing the strength of small thin walled tubes is to pressurize the inside volume and obtain the strength value at which the tube bursts under the internal pressure. A custom burst-test instrument was constructed to obtain the average strength value of differing types of small ceramic tubes. The mechanical properties of 8 mol% yttria-stabilized zirconia (8YSZ) and NiO-YSZ tubes were investigated and are discussed. An average burst strength of 97 ± 28 MPa was observed for 8YSZ electrolyte tubes and 72 ± 23 MPa and 70 ± 16 MPa for as-sintered and reduced anode support tubes, respectively.     

The construction and stability of a surface mounted vibratingwire strain guage

The construction of a surface–mounted vibratingwire strain gauge for use in creep tests is described and some results on the stability of the gauge are presented. Novel features of the gauge construction include a pressed one–piece clamp for holding the wire and provision for a secondary strain measuring system. Relaxation of the vibrating wire caused relaxation of the gauge. There was no significant relaxation due to the clamping method. Cyclic straining of the gauge before use virtually eliminated zero displacement. The use of an unloaded control specimen, which is gauged at the same time and with the same wire tension as the creep specimen, is recommended. Alternatively, relaxation measurements on the wire can be used to correct measured strains. Either of these procedures will reduce the effect of gauge relaxation on creep strains to less than 3 μstrain.     

椭圆管换热器对空调室内机声场影响的数值模拟

椭圆管换热器由于良好的流动和换热特性,在换热设备中有广泛的应用。本文利用计算流体力学方法,对椭圆管翅片换热器应用于空调室内机的流场和声场进行数值模拟,并与圆管作对比。计算结果表明,换热管形状对贯流风机内部偏心涡的形成位置和大小没有影响;与采用相同截面积的圆管翅片换热器的室内机相比,相同条件下,采用椭圆管换热器对于室内机增加风量,改善制冷性能,降低噪声尤其是低频噪声方面有良好的效果。其中,长短轴之比为2的椭圆管可以降低室内机噪声4 d B。     

电磁胀形管坯所受磁压力的瞬态分布

管坯所受磁压力的准确求解是电磁成形变形分析,优化成形系统工艺参数的基础.通过ANSYS/EMAG软件,用远场单元来说明磁场在远场区间的耗散问题,对电磁胀形时作用在管坯上的磁压力进行准确计算.在线圈长度一定的条件下,讨论了管坯尺寸对磁压力瞬态分布和磁场扩散的影响,并根据管坯端部径向磁压力和中部径向磁压力的比值,提出以磁压力分布不均匀系数来反映磁场不均匀分布的程度.计算结果表明:当管坯和线圈的相对长度大于1时,管坯上与线圈等高处承受轴向拉应力,磁场扩散现象不严重;当相对长度小于0.92时,管坯端部承受轴向压应力,磁场扩散现象严重,相对长度0.92时为电磁胀形均匀成形的条件.     

Response of high resolution drift tubes to relativistic heavy ions

We report the results of various tests undertaken in a program to develop a drift tube hodoscope for a cosmic ray balloon experiment intended to search for extragalactic antimatter. Included are studies of mechanical integrity, electron drift velocity, tube gain, space charge saturation effects as measured for relativistic iron nuclei, and delta ray backgrounds associated with signals from iron projectiles. Implications of the results of these studies with regard to the use of drift tubes on baloon borne experiments are discussed. It is found that a spatial resolution of σ ～ 300 μm can be achieved over a dynamic range from Z = 20 to 30 with little degradation from delta ray effects for suitably chosen tube gains and discriminator threshold settings.     

Drift time measurements in limited streamer tubes

We have investigated the performances of drift time techniques applied to limited streamer tubes. A resolution of ∼ 150 μm in the coordinate across the wire is found and a way to solve the left-right ambiguity is presented.     

Numerical simulation and experimental analysis of refrigerants flow through adiabatic helical capillary tube

In the present study, two-phase refrigerant flow is simulated using drift flux model for straight and helical capillary tubes. The conservation equations of mass, energy and momentum are solved using the 4th order Runge–Kutta method. This model is validated by previously published experimental and numerical results and also by experimental results presented in this work. The effect of various parameters such as inlet pressure, inlet temperature, sub-cooling degree, and geometric dimensions are studied. The results of the present study show that for the same length and under similar conditions, mass flux through helical capillary tube with coil diameter of 40 mm are about 11% less than that through the straight tube, where the helical tube length is about 14% shorter than the straight one for the same refrigerant mass flux.     

强旋薄壁管材z-θ向残余剪应力的测量方法

为建立旋压薄壁管材残余剪切应力的测量方法,并估算强旋2024Al样品管的残余应力,沿单侧纵向切开管段并测量了变形.对变形进行简化的基础上,以弹性力学方法推导出了残余剪切应力的算式,并计算了样品管材的残余应力大小.结果表明：样品管材存在显著的z-θ向残余剪切应力,应力的大小与切口两侧的轴向错开量成正比,应力沿壁厚的分布接...