用激光技术测定液体中的声速和等熵压缩性系数

本文应用根据激光光声原理和技术建立的流体热力学性质测量实验装置，测定了七个温度下苯、四氯化碳液体中，苯与四氯化碳二元溶液中的声速（ｕ）、密度（ρ），计算了等熵压缩性系数（Ｋ＿ｓ）等热力学数据。用多项幂级数，以最小二乘法拟合声速ｕ与温度ｔ的数学关系。实测的声速值与文献值比较，相对误差小于０．０４％，等熵压缩性系数与文献数据也相当吻合。     

Molar volume and ultrasonic studies of europium soaps in mixed organic solvents

The ultrasonic velocity and density measurements of europium soaps in a mixture of benzene and methanol (3:2, vol/vol) were used to evaluate various acoustic parameters and molar volume and to determine the critical micelle concentration. The results showed that the ultrasonic velocity, specific acoustic impedance, molar sound velocity, and molar compressibility increase, and intermolecular free length, adiabatic Compressibility, and relative association decrease with increasing concentration and chainlength of the soap. The results were interpreted in terms of soap-solvent interaction.     

Propagation of the Chain Explosive‐Decomposition Reaction in Silver Azide Crystals

The velocity of the chain explosivedecomposition reaction in silver azide whiskes has been measured (1500 m/sec). The measured velocity is identified as the propagation velocity of the diffusion front of holes generated in the course of explosive decomposition.     

水流掺气对明流泄洪洞及挑坎水力特性的影响

水流充分掺气可以避免高流速泄洪设施发生空蚀,但也会改变相关水力特性。通过对某大坝泄洪洞掺气设施水力模型试验及关于水流表面自掺气发生条件的相关分析,提出了在全程流速超过38 m/s,长度达550 m的明流洞内仅布置一级掺气设施的建议,较通常情况减少了两级;并针对泄洪洞出流方向与河道流向交角达60°的特点,研究提出了一种大差动异型鼻坎消能工。水工模型试验成果表明,其挑流水舌沿河道纵向扩散良好,水舌外缘与河道对岸保持了30 m以上的安全距离。该泄洪洞建成后经历了高水头、较长时间的泄洪运行,明流洞和鼻坎消能工均无空蚀发生,但挑坎水舌却冲刷到对岸边坡。     

"大肚子"环空液体流动规律的实验研究

针对现场固井在"大肚子"环空段封固质量较差的情况,本文研制了含有"大肚子"环空段的注水泥(液体)流动模拟实验装置。利用该装置,研究井径扩大率、流量、液体流变性能等对"大肚子"环空处的流速场的影响规律。得到了不同情况下(井径扩大率、流量、液体流变性能等变化)"大肚子"环空段不同位置径向截面的流速曲线变化情况,为研究"大肚子"环空段的顶替机理提供了一定的数据资料。     

Detonation velocity of BTNEN/Al

The effect of the addition of Al on the detonation velocity of bis(2,2,2-trinitroethyl) nitramine (BTNEN) was studied experimentally. It is shown that the dependence of the detonation velocity of BTNEN on the initial density is nearly linear, and a 75/25 BTNEN/Al mixture is characterized by an increase in the slope of the dependence with increasing density. The addition of Al decreases the detonation velocity of BTNEN. The density range characterized by a maximum decrease in the detonation velocity is determined. A comparison of experimental detonation velocities of BTNEN/Al mixtures with literature data obtained by calculations taking into account a possible change in the phase state of Al₂O₃ showed that the thermodynamic model used in the calculations needs to be improved. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 125–130, July–August, 2006.     

Particle velocity and solids circulation rate in a jet-spouted bed

Radial distribution of particle velocities, solids circulation rate and radial variation in bed voidage in a jet-spouted bed were investigated in a 0.2 m diameter conical-cylindrical column. The upward particle velocity is strongly dependent on gas velocity and its radial profile is the Gaussian. The solids circulation rates are of the same order of magnitude as those in a conventional spouted bed and are proportional to the gas velocity. Estimation of the variation in bed voidage in the radial direction revealed that the annulus voidage of about 0.90 was greater than the spout voidage of around 0.70. This tendency is contrary to that in a conventional spouted bed.     

Sliding‐Mode Velocity Control of a Two‐Wheeled Self‐Balancing Vehicle

Underactuated vehicles are those in which the number of control inputs is less than the degrees of freedom to be controlled. Using actuated wheels, velocity control of the two‐wheeled self‐balancing vehicle drives the vehicle at a desired speed and balances the body of the vehicle. First, we investigate the effects of friction on the wheel and derive the hybrid model of rolling and slipping. Second, we propose a nonlinear sliding mode velocity control scheme for the pure rolling model of the two‐wheeled vehicle. We present the design of the corresponding sliding surfaces and internal dynamics of the two‐wheeled vehicle. Our stability analysis reveals that the proposed sliding mode method can guarantee the asymptotic stability of the error dynamics for velocity control of the underactuated vehicle. Compared to linear optimal control, our numerical simulations demonstrate that the proposed sliding mode schemes can effectively control the velocity under the circumstances of parametric variations, emergency braking, and rapid acceleration in slippery road conditions. The proposed velocity control and the simulation improve our understanding on designing velocity control of the two‐wheeled self‐balancing vehicle.     

旋转变压器信号的标定与解调

针对检波后信号存在直流偏置、幅值不等和相位偏移等问题,采用梯度估计算法,对检波后的包络信号进行离线标定;并设计了基于状态观测器的旋转变压器-数字转换(RDC)算法,对标定后的包络信号进行解调.试验结果表明,梯度估计算法收敛速度快,估计精度高.与反正切法相比,所设计的RDC算法不需通过数值差分即可获得角速度信息,干扰抑制能力强,角位置和角速度估计精度高.     

淤浆鼓泡床中固体粒子的悬浮特性

研究了三相鼓泡床中的临界固含率,以空气作气相,水、乙醇-水、丙酮-水、萜松醇-二甲苯作液相,石英砂、煤、雷奈镍作为固相。分析了鼓泡柱的高径比、气体速度、固体粒子的大小和比重、液体的粘度对临界固含率的影响,提出了含有这些参数的无因次数群的关联式,讨论了本文提出的关联式和文献报导的差别。