Propulsion characteristics of wing-in-ground effect dual-foil propulsors

Propulsion characteristics of wing-in-ground effect propulsors were investigated using a comparative analysis of thrust and powering characteristics between wing-in-ground (WIG) effect thrusters and traditional screw propellers. WIG thrusters were found to have constant thrust production and efficiency, nearly independent of speed of advance, as contrary to screw propellers, whose optimum efficiency occurs at only one speed point. To produce the same amount of thrust as equivalent screw propellers, WIG thrusters have to work under heavily loaded operating conditions. WIG thrusters were also found to produce a relatively lower but nearly constant efficiency and thrust, independent of speed. Another distinguishing propulsion characteristic revealed for WIG thrusters is that they are capable of operating at much higher speeds, in a range of three to six times that of screw propellers of the same size. While the speed range of screw propellers is mainly limited by their geometric pitch, the speed range of WIG thrusters has no speed limit in ideal fluid. In reality, the speed range is only limited by viscous drag and cavitation, or compressibility, in water or air, respectively. This suggests a potential for WIG thrusters of higher speed application than screw propellers. An experimental investigation and validation of the propulsion system is warranted. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.

Hydroelastic dynamic characteristics of a slender axis-symmetric body

The slender axis-symmetric submarine body moving in the vertical plane is the object of our investigation. A coupling model is developed where displacements of a solid body as a Euler beam (consisting of rigid motions and elastic deformations) and fluid pressures are employed as basic independent variables, including the interaction between hydrodynamic forces and structure dynamic forces. Firstly the hydrodynamic forces, depending on and conversely influencing body motions, are taken into account as the governing equations. The expressions of fluid pressure are derived based on the potential theory. The characteristics of fluid pressure, including its components, distribution and effect on structure dynamics, are analyzed. Then the coupling model is solved numerically by means of a finite element method (FEM). This avoids the complicacy, combining CFD (fluid) and FEM (structure), of direct numerical simulation, and allows the body with a non-strict ideal shape so as to be more suitable for practical engineering. An illustrative example is given in which the hydroelastic dynamic characteristics, natural frequencies and modes of a submarine body are analyzed and compared with experimental results. Satisfactory agreement is observed and the model presented in this paper is shown to be valid.

Characteristics of a 4-fold segmented clover detectore

Four high-purity germanium 4-fold segmented Clover detectors have been applied in the experiment of neutron-rich nucleus N-21. The performance of those, four Clovers have been tested with radioactive sources and in-beam experiments and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in difficult crystals of one Clover detector with the energy of gamma ray, and absolute full energy peak detection efficiency curve, were presented.

Meat characteristics of Qinghai yak and semi-wild yak

Six domestic yaks aged 6 years, comprising three culling male and three culling female yaks, from the Qinghai Lake area and three male semi-wild yaks aged 6 months from Datong Yak Farm were used to detect the levels of amino acids, mineral elements, residual heavy metals and pesticides in yak meat. The results showed that there was little difference in amino acid levels for different types of yak by age and sex. The meat of the adult male yak was 7.35 mg/kg higher in calcium (P < 0.05) and 124 mg/kg higher in phosphorus (P < 0.01) than that of the adult female yak. There was an obvious difference in zinc content, and there was also a significant difference for copper and sulfur between adult male and female yaks (P < 0.01). Iron was 8.85 mg/kg higher in semi-wild yaks than in domestic yaks, but there were no differences for other minerals. The levels of residual heavy metals and residual pesticides were well within those allowed by the National Standard of China. Furthermore, the data showed that introducing wild yak's blood did not result in a quality change in the domestic yak meat. Yak meat from Qinghai Plateau has the characteristics of being non-polluted and rich in amino acids in comparison with local yellow cattle meat.

REE characteristics of the Fanshan alunite deposit in Zhejiang Province, China

REE geochemistry data from the Fanshan alunite deposit indicated that its ore-forming materials came chiefly from the country rocks, with δCe〉0 for alunite ores. According to the differences in δEu, the alunite ores were divided into three types： weak negative Eu anomaly, weak positive Eu anomaly and remarkable positive Eu anomaly. The phenomena of Ce-enrichment in the ores indicated that the Fanshan alunite deposit was formed in an oxidizing environment. Variations in fO2 are corresponding to those in δEu： Eu anomaly varies from negative to positive with increasing fO2. And two other important factors may impact the occurrence of Eu anomalies： the contents of alkaline feldspar and the protolith structure in the mineralization period.