Applied Mechanics and Materials Vols. 291-294

Abstract: The transformer fault diagnosis expert system design knowledge representation and reasoning mechanisms are the key issue. Characteristics of transformer fault diagnosis system based on human experts, learning on the basis of the human expert diagnosis of transformer faults, to build a transformer fault diagnosis expert system of systems architecture, knowledge representation and reasoning mechanisms for a more detailed analysis and discussion.

Abstract: Hilbert Huang Transform (HHT) couldn’t effectively identify voltage interruption and voltage dips. Frequency comparison method was applied to identify the two situations in this paper. The simulation results showed that the magnitude of the Intrinsic Mode Functions (IMF) components and instantaneous frequency fluctuations were not exactly the same, when the magnitude of the voltage sag was different. The magnitude of the voltage sag was larger, the average value of the amplitude of the IMF components was smaller and the instantaneous frequency fluctuations were greater. During the period of voltage interruption, the instantaneous frequency of the IMF components was almost zero and the average value of the IMF components was relatively larger. So the instantaneous frequency of voltage interruption and voltage dips different characters can help to identify the two situations and the results of the example verify to be a practicality method.

Abstract: This paper designed a fpga-based ultrasonic flowmeter, and used verilog language design fpga control unit.The microcontroller was the core of the ultrasonic transceiver circuit. Peripheral circuit is designed to be simple and reliable, the fpga advantage in raising the maximum clock frequency, greatly improves the measurement accuracy of the design.

Abstract: The main objective of the article is to stimulate interest of the consumers for the green energy considering the environmental and the financial impact (in this case by increasing productivity) of this one. For these arguments, this article proposes a real application, with autonomy in the power supply, for control the temperature in the hive using energy from alternative sources (through a solar panel). The temperature regulation is controlled by a microcontroller. For setting the temperature of the hive some bees are used at the expense of honey production. If there would be no need to adjust the temperature of the hive bees when the hive would increase productivity (worker bees population and honey production).

Abstract: The corrosion behavior of AZ91-0.4%Nd alloys was investigated by immersion test in 3.5wt.% NaCl at 25°C. The phase compositions and microstructure of the AZ91-0.4%Nd alloy were characterized by XRD and OM, respectively. The results show that the number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency, and the granular or acicular Al₃Nd phase precipitate in matrix.The corrosion products of the AZ91-0.4%Nd alloy mainly composed of Mg(OH)₂ and Al. The addition of Nd element significantly refine the microstructure and improve the compactness of corrosion products of AZ91-0.4%%Nd magnesium alloy, as a result the corrosion resistance of alloy was improved obviously.

Abstract: Sandwich composite is a new structure of acoustic stealth structure, implementing both loading and acoustic stealth. The syntony of cavum can improve the absorption effect in low frequency. This paper uses FEM analysis method, which has been proved theoretically with typical cases and experimental results, to analyze the effect of sandwich material parameter and cavum physical in water backing. The reflection and absorption coefficient in different module, poisson ratio, and density of sandwich, and different depth, location, diameter, interval, and shape of cavum are analyzed. It can support the acoustic design of underwater sandwich composite structure with cavum.

Abstract: The Co/ZrO2-Al2O3 catalysts were prepared by impregnation method, and characterized via quantitative XRD, H2-TPR, and N2 adsorption-desorption techniques. The study showed that the addition of ZrO2 increased the interaction between active component and support, decreased the average crystallite size of Co3O4 and improved its dispersion. The performance tests presented that the Co/ZrO2-Al2O3 catalysts with bimodal pore distribution had high CO conversion and were more selective towards the gasoline fraction (C5-C10) and diesel fraction (C11-C18).

Abstract: The paper presents the experimental results obtained on the pipes welded joints made of TP 347 steel in normal state, NT (welded) and heat-treated state, TT for post-welding stabilization. Heat treatment for stabilization was performed in an electric furnace which provided the process parameters (Theat = 900°C, Vheat = vcooling ≈ 300°C, etc.) and a precision temperature of ±10°C to 1000°C. Chemical compositions of TP 347 steel pipe and of the filler material (ER 347) have values falling within the manufacturing standards (Cr = 17 ... 19% and Ni = 9... 13%). In the specific areas of the welded joints were detected austenitic structures with heterophasic areas of ferrite and complex carbides areas, having the hardness between 162 and 225 HV10. No welding and heat treatment defects were detected, such as cracks and microcracks. The mechanical strength (Rp0,2 and Rm), determined on the base metal and on the welded joints presents high values. Thus, for the base metal were obtained values of Rp0,2 of minimum 212 N/mm2, respectively values of minimum 523 N/mm2 for Rm. For the welded joints, Rm has values between 522 N/mm2 and 527 N/mm2. All the values obtained are higher than those required by ASTM A370standard. The base materials in NT and TT state presents high values of impact energy KV at 20°C, between 72J and 78J, and for the welded joints, the values of KV are between 53J and 60J, with ductile breaking aspect of the specimens’surfaces. The surfaces of the tested specimens for resistance to intergranular corrosion according to ASTM A 262-2010, Method E, presented not specific defects, attesting a corresponding behavior of the intergranular corrosion of TP347 steel and of the welded joints made of the pipes having the dimensions of ø219 x 8.18 mm. The values of the chemical, structural, mechanical and intergranular corrosion characteristics determined on specific samples evidence a high quality of the base material and of the welded joints of TP 347steel pipe, conducted by qualified welding technology, commonly used in the manufacture of components from chemical and petrochemical industries.

Abstract: Failure analysis of fracture of 35CrMo bolt was investigated. It was analyzed by means of morphology and microstructure analysis, chemical composition analysis, hydrogen content analysis, scanning electron microscope (SEM) micro-morphology of fracture surface, electronic differential system (EDS) corrosion products analysis. The results showed that the cause of fracture of 35CrMo bolt was stress corrosion cracking. Working stress of the bolt，H2S in surroundings and the high hardness of the bolt combined caused cracking of the bolt. Suitable heat treatment for the 35CrMo bolt is suggested.

Abstract: Because of the discharging of the titaniferous blast-furnace, large quantities of titanium resource have run off ,its utilization has been the focus of people'cencerning. This article introduced the present research state of the titaniferous blast-furnace'complex utilization,and it analysed the open question and the feasibility of titaniferous blast-furnace'applying at photocatalysis area.This article also prospected the titaniferous blast-furnace's research foreground.