Advanced Materials Research Vols. 311-313

Abstract: FBTIG(Flux Bounded TIG)welding experiments for aluminum alloy were made using five species of single-component activating fluxes, including SiO₂、TiO₂、CaF₂、MgO, and NaCl, which was carried out to investigate the effects of flux gap and activating fluxes on weld formation. The mechanism of increasing welding penetration was analyzed linked with the change of arc shape in FBTIG. The experimental results indicate that five species of single-component activating fluxes can increase weld penetration obviously. Specifically, SiO₂ can increase weld penetration remarkably. When flux gap is 4mm, the D/W (depth/width) ratio of weld for FBTIG welding reaches 0.59. The significant increase of weld penetration is the result of comprehensive effect by arc contraction and reversal of the surface tension gradient in the liquid metal.

Abstract: Unmanned surface vehicle has been the concern of the researchers at home and abroad as a new kind of unmanned platform ,especially for the middle-low speed resistance performance .An optimization method is proposed in this paper to find a hull form with perfect resistance performance in middle-low speed .This paper combines wave resistance and non-linear programming , Moreover, some hull forms are optimized to meet the combination of optimization punishing function with practical requirements and objective function to obtain Optimization form. The paper compared wave-making resistance coefficient and Total resistance (Newton) of Unit displacement (ton) between patent form and Optimization form to Show the feasibility of this method .The optimization results can provide reference for the subsequent hull form.

Abstract: The uncertain and random characteristics of wind energy make the problem of wind turbine control interesting and challenging. This work investigates an adaptive method for variable speed control of wind turbines under varying operation conditions. For fixed-speed operation of wind turbines, maximum power conversion can be achieved only at a particular wind speed, thus variable speed control of wind turbines is of practical interest in enhancing wind turbine operating efficiency over wide wind speeds. Based on the nonlinear dynamic model of wind turbine, adaptive algorithms are developed in accommodating unknown system parameter uncertainties. This method is shown to be able to achieve smooth and effective tracking of rotor angular speed to capture maximum wind energy. The effectiveness and adaptation of the proposed approach is validated via numerical simulation.

Abstract: A cross-shaped pattern was formed on the surface of Ba_0.5Sr_0.5Co_0.8Fe_0.2 O_3−δ oxygen permeation membrane by laser ablation in order to increase the specific surface area of the membrane. The membrane was used to assemble a reactor for partial oxidation of methane (POM) to syngas in the present of Ni/ZrO₂ catalyst. The CH₄ conversion and CO selectivity of the membrane reactor can reach 98.8% and 91.5%, respectively, and the oxygen permeation flux through the membrane was 11.0 ml/cm² min at 850°C. The effect of space velocity (SV) on CH₄ conversion rate and CO selectivity in such reactor was discussed.

Abstract: This paper proposes a design method how to realize a digital-high-power (DHP) lead-acid battery (LAB) charger. The main control unit P89LPC933 real-time collects the voltage and current of the charger. Then the unit sends out the control signal to pulse width modulator SG3525A, controlling the voltage and current. It co-operates the external circuit as well. This paper innovatively proposes 4-stage charging control method and strategy. This paper compares the typical chargers on the market with the one proposed by the authors in terms of horizontal and vertical dimension.

Abstract: Rare earth antimonide stoichiometric compounds RE₂FeSb₂ (RE=Y, Dy, Er) were prepared and examined by X-ray diffraction technique. XRD analysis showed that these alloys were crystallized in cubic RESb-type structure. The electrochemical properties of these alloys such as discharge capacity and cycling performance were investigated by battery testing instruments in alkaline electrolyte. Electrochemical tests discovered that the alloys RE₂FeSb₂ (RE=Y, Dy, Er) had two clear and wide discharge potential ranges. Furthermore, the first charge and discharge cycle showed that the discharge capacities of RE₂FeSb₂ (RE=Y, Dy, Er) were about 12.8,15.1,16.0 electron/formula, respectively. The ferroalloy electrode of RE₂FeSb₂ (RE=Y, Dy, Er) had latent superiority in electrochemical properties.

Abstract: With the development of continuous welded rail (CWR) in China high speed railway, the innovative study has been carried out for the welding technique of track key part. Firstly, the paper introduces the traditional rail welding technique and its problems in China, and then, it proposes the new “SQ” gas welding technique on that basis, finally, it describes “SQ” gas welding technique in terms of technical feature, flow, economic benefit and application, which will be conductive to China railway track welding.

Abstract: Micro-tubular solid oxide fuel cell (SOFC) has been fabricated with NiO-YSZ hollow fiber as anode support and SrFe_0.9Sb_0.1O _3−δ-Sm_0.2Ce_0.8O_1.9 (SFSb-SDC) composite cathode. The NiO-YSZ hollow fiber anode was prepared by the immersion-induced phase inversion technique and shows a special asymmetrical structure with long and large finger-like porous structure near the lumen side of the hollow fiber. A thin and dense electrolyte membrane (about 12μm) was deposited on the anode by a vacuum-assisted dip-coating process. The performance of the as-prepared micro-tubular SOFC was tested at 600-800°C with humidified H2 as fuel and ambient air as the oxidant. The peak power densities of 462.8, 336.6 and 201.4 mWcm^-2 can be obtained at 800, 700 and 600°C, respectively. The experimental results indicate that the cobalt-free SFSb was a promising cathode material and the prepared YSZ-based micro-tubular SOFC has potential applications as power sources for portable devices.

Abstract: This paper performs a numerical investigation of a micro-electro-mechanical-system (MEMS) based capacitive viscometer. The viscometer includes a pre-stressed membrane interacted with a trapped air and a polymer solution, as well as a semi-permeable membrane that allows water and small molecular to pass through freely. A very simple modeling method is presented to solve the complicated problem. First, the fluid property of the polymer solution is estimated using relaxation time estimation. Second, a two modes vibration assumption of the pre-stressed membrane is proved using structure-air-interaction. Then the leakage through the semi-permeable membrane is also estimated using the volume flow with lubrication theory. Finally, the equivalent model of the glucose sensor is built using very simple vibration equations, the capacitance is also calculated. The simulation results show that the trapped air plays a significant role for the vibration of membrane, the volume should be large enough to reduce the nonlinear effects caused by the trapped air, which unfortunately causes the capacitance much to be smaller.

Abstract: In accordance with the present status of real –time measurement for agricultural machine in the field with burdensome in labors, unsafe in testing and backward in testing method.Wireless data acquisition system for testing based on LabVIEW is introduced in the paper. This system integrates sensor technology, WLAN technology, virtual instrument technology and measurement technology. Compared with running cables test, the Wireless Data Acquisition system becomes safe and easy for moving machine. This system can provide a robust, two –way, TCP/IP connection, which can be linked to the networks of Internet easily. For mobile test or bad- condition measurement, a wide application is pointed out in the end.