Winding Displacement Research Articles

Sedimentology of playa lakes of the northern Great Plains

The semi-arid plains of western Canada and northern United States contain a large number of saline and hypersaline lakes, with many of the shallow lakes exhibiting playa characteristics. For over 60 years a number of these playas have provided a source of valuable industrial minerals. The present study deals with the modern sediments and sedimentary processes operating in selected playa basins located throughout the northern Great Plains region.The playas generally occupy small, closed basins commonly having an elongate, riverine shape. Most of the brines are dominated by sodium, magnesium, and sulfate ions; however, examples of lakes rich in chloride and bicarbonate ions are also present. Significant variation in the brine chemistry can exist on a seasonal as well as a diurnal basis. The modern sediments of the playas consist of: (1) very soluble salts of mainly sodium and magnesium sulfates and carbonates; (2) sparingly soluble precipitates, including calcite, protodolomite, gypsum, and mixed layer clays; (3) detrital minerals consisting dominantly of quartz, carbonates, feldspars, and clays; and (4) organic matter.Much of the physical and mineralogical character of the playas is due to processes that are largely of a chemical nature and are associated with either evaporative concentration of the brines or groundwater discharge. The most significant processes include: cyclic flooding and desiccation of the playa surface, formation of salt crusts, efflorescent crusts, spring deposits, and intrasedimentary salts, formation of solution pits and chimneys, wind displacement of brines, and periodic detrital sedimentation by sheet flow and wind. These processes combine to create a very dynamic modern depositional environment. The establishment and prolonged maintenance of delicate physical and chemical equilibria have allowed the deposition of over 40 m of salt in some basins.

Six Phase Synchronous Machine with AC and DC Stator Connections, Part II: Harmonic Studies and a Proposed Uninterruptible Power Supply Scheme

The relationships of the mutual leakage inductances with winding displacement angle and pitch for a number of practical six phase winding configurations are derived. The voltage harmonic distortion and torque pulsation of a six phase machine with AC-DC stator connections are characterized in terms of the operating load conditions, winding displacement angle, pitch, converter commutating reactance, and rotor impedance. It is shown that for most operating conditions a displacement angle of 300 appears to be optimum with respect to voltage harmonic distortion and torque pulsation. The effects of neglecting the mutual leakage coupling on the voltage harmonic distortion, torque pulsation and transient characteristics of the machine are examined. A novel application of the six phase machine in an uninterruptible power supply scheme is proposed. Results on the dynamic performance of the proposed UPS scheme to input voltage spikes and to a normal supply interruption are included.

短絡時の回転機固定子巻線端部の変形挙動と強度

A stress measurement technique was developed in order to reduce the disturbance caused by electromagnetic field. Using this technique, a series of short circuit tests were carried out on 21000kVA two-pole turbine generators. The stress and displacement induced on the stator end windings were examined under various short circuit voltages. The mechanical strength of the stator end windings was discussed in comparison with the measured stress and the bending strength of stator windings and was also discussed in relation to the variations in tangent delta and breakdown voltage characteristics. The results obtained are as follows.(1) The stress measurement technique developed in this study is effective for the stress measurement on electric appliances which are exposed to strong magnetic field.(2) The stator end windings can be bent repeatedly tangentially in the direction to increase the stator end windings' curvature and radially in the opposite direction to the rotor.(3) The maximum amplitudes of stress and displacement of the stator end windings increase in proportion to the square of short circuit voltage. But they depend on the magnitude of the direct component in short circuit current and tend to increase with it.(4) When the direct current component appears relatively large, the predominant frequency of the stress and displacement is 60Hz, but with decreasing of direct current component 120Hz frequency becomes predominant. When it is small, 120Hz frequency is predominant.(5) It is considered that within this test condition there is no mechanical damage which would cause the reduction of electric characteristics under further service operation.

Dispersal, seasonal flight activity and winter survival of the oak stem Phylloxerid Moritziella corticalis (Kalt.) (Homoptera, Phylloxeridae)

AbstractThe dispersal and seasonal flight activity of the oak stem Phylloxerid (Moritziella corticalis (Kalt.)) was studied at three localities in southern England by means of field observations and by sticky trap and suction trap catches. Wind displacement of first-instar crawlers occurred mainly during the winter months (76.2%) when this stage of the life-cycle is most active and abundant. No desiccation of these larvae was observed. The flight period of the sexuparae extends from the end of July to the end of October, and in most years three peaks of flight activity were discernible. A succession of days with low temperatures sometimes prevented migration, but large catches usually followed these low temperature spells. Analysis has shown that the temperature threshold for flight was about 17·2°C. Individuals flying at the start of the flight period were significantly smaller than those flying at the end of the season, possibly because factors affecting the host-plant may also effect changes in breeding and development of the insect. In a frost gradient apparatus, the overwintering first-instar larvae of M. corticalis were cold hardy, the LT30 being -23·7°C.

Induction Machine Analysis for Arbitrary Displacement Between Multiple Winding Sets

The steps in t he applied voltages of a three-phase, inverter-induction motor drive system cause undesirable pulsations in motortor By using multiple inverters connected to a multiphase machine with appropriate winding displacements, significant improvement in system performance is possible. The winding displacements required, however, are not necessarily the symmetrical displacements used in standard multiphase machines. This paper sets forth an improved method for analyzing many types of unsymmetrical, as well as symmetrical, multiphase induction machines. The simulation of a 7.5-hp induction machine with two three-phase sets of stator windings fed from two six-step inverters illustrates the application of the method of analysis and shows how the machine torque characteristic may be improved by proper spacing of the winding sets.

A Vectorially Integrating Anemometer

An anemometer is described which allows the integrated wind displacement in the four cardinal directions to be recorded directly. The instrument comprises a cup anemometer movement and a wind vane. The movement of the cups is communicated through gearing to a ball floating in mercury, and the plane of rotation of the ball is governed by the wind vane. Rotations of the ball in the four cardinal directions are measured by light friction wheels which transmit electrical impulses to counters.