AC measurements of the minimum longitudinal resistance of a QHEsample from 10 Hz to 10 kHz

AC measurements of the longitudinal resistance, R_xx, of a quantum Hall effect (QHE) sample have been made in a frequency range from 10 Hz to 10 kHz. The results show no frequency effect on the minimum value of R_xx corresponding to the quantum numbers i=2 and i=4, within the measurement resolution of 0.5 mΩ. Therefore, the influence of frequency on the value of the quantized Hall resistance, R_H, should not exceed a few parts in 10⁹ . Some unwanted effects detected during the development of the resistance bridge have been pointed out     

Coriolis effects in the dynamics of a rotating elastic structure

Summary Small oscillations of a rotating elasticum with a mass at the free end are investigated with Poincaré-Lindstedt series. It is shown that the mass moves on a figure-eight shaped curve in a direction determined by the sign of the angular velocity and hence that the Coriolis force influences the motion.     

Motion of a solid sphere in a general flow near a plane boundary at zero Reynolds number

It is demonstrated how the hydrodynamic force and moment of force acting on a solid sphere may be calculated when it is placed at rest at an arbitrary position in a two dimensional flow at zero Reynolds number in which the region of flow is bounded by either an undeformable planar free surface or by a plane solid wall. The results so obtained are used to calculate the motion of a freely moving solid sphere in an asymmetric vortex in the presence of an underformable free surface. It is seen that the sphere, depending on the direction of the undisturbed flow, will either spiral into or out of the vortex. This implies that when a dilute suspension of such spherical particles undergoes such a vortex motion in the presence of the free surface, the vortex will either fill up with particles from the surrounding flow or become devoid of particles.Deceased, July 31, 1995     

Pulsed phase-locked loop calibration over frequency

This paper presents a method of correcting for unwanted phase shifts introduced by interchanging ultrasonic transducers and other measurement system components when using the pulsed phase-locked loop (PPLL) ultrasonic system. Theory is derived mathematically separating phase errors into their constituents. The relationship to a previously derived method of determining the number of periods into the tone-burst, at which the system samples, is established, and a method of adjusting this number to be an integer is presented. Implementation of the technology on a computer is demonstrated through experimental results on transducers of differing frequencies and diameters. Sensitivity to path-length is tested. This work has resulted in a straightforward means of calibrating transducers in conjunction with PPLL measurements using a single, fixed reference block     

Propagation of a quasi-shear horizontal acoustic wave in Z-Xlithium niobate plates [and conductivity sensor application]

It is found that an acoustic wave which is nearly polarized in the shear horizontal (SH) direction can propagate along the X axis of a Z-cut lithium niobate plate if the ratio h/λ, where h=plate thickness and λ=acoustic wavelength, is less than about 0.5. Attractive properties of this quasi-SH wave include: (1) phase velocity nearly constant for all values of h/λ; (2) ability to propagate in contact with a liquid medium; and (3) electromechanical coupling coefficient as high as 0.15. These properties make the wave attractive for use in a variety of sensor and signal processing applications. An example of sensor applications is illustrated by using the wave to measure conductivity of liquids (aqueous KCl solution). The frequency of a 12-MHz quasi-SH mode oscillator fabricated on a 0.48 wavelength thick Z-X lithium niobate plate is found to vary by more than 80 kHz for variation in KCI concentration from 0 to 0.15%     

Multiobjective evaluation of advanced manufacturing system technology investments with risk

Advanced manufacturing system technologies are difficult to evaluate using ordinary financial measures owing to the presence of risk and significant intangible factors. In this paper a methodology is proposed that quantifies financial, strategic, and tactical attributes of each alternative. Attribute values are denned for each period of project life. Both project life and attributes are treated as random variables. Attributes are discounted to the current time and the multiple objectives are combined by composite programming. The distribution of the combined objective is estimated. The procedure is demonstrated on an actual case study.     

Testing images independently of translations and linear deformations

This article considers the theory of construction of criteria that are independent of the motions of images, as as well rotations and linear deformations. A method is presented for construction of new types of criteria that have the following distinctive features: they make it easy to construct functionals for measurement of the characteristics of motion of standard images; the theory can easily be extended to the case of grey-scale and colored images; the criteria that are obtained are amenable to parallel computation; the proposed theory makes it easy to construct new criteria. Translated from Izmeritel’naya Tekhnika, No. 8, pp. 13–16, August, 1996.