Advanced Materials Research Vol. 709

Abstract: Drilling process is a complicated system with characteristics of uncertainty, fuzziness and time-varying. A new way of the fault diagnosis based on RS-SVM (Rough Set and Support Vector Machine) was proposed in this paper. The related engineering factors were reduced by Rough Set theory and the main factors of the drilling process were obtained. Then the Support Vector Machine was used to establish the diagnosis models, and then the problems that the traditional SVM cannot deal with dynamic data and are prone to dimension disasters with large samples were avoided. The application in Ha35 well, Liao He Oilfield indicates that the system can diagnose the type of faults quickly and accurately. So the method can be used to diagnose the drilling process.

Abstract: Hybrid suspension system with permanent-magnet and electromagnet consumes little power consumption, and can realize larger suspension gap. We took magnetic flux signal as a state variable, and put this signal back to suspension control system. So we got the hybrid suspension mathematical model based on magnetic flux signal feedback. With application of MIMO feedback linearization theory, we can realize linearization of the hybrid suspension system. Then PIDB (proportion, integral, differentiation, magnetic flux density B) controller was designed. Some hybrid suspension experiments had been done on CMS04 magnetic suspension bogie of NUDT (National University of Defense Technology) in China. The experiment results denote that hybrid suspension control algorithm based on magnetic flux signal feedback designed has more advantages than traditional position-current double cascade control algorithm. Obviously the robustness and stability of hybrid suspension system have been enhanced.

Abstract: Fast tool servo is increasing applied to manufacture optical freeform surfaces, which are adopted in aerospace, imaging, bioengineering, energy fields to improve the performance of the system, simplify the structure of the system and lower cost. The existing FTS have limited stroke and bandwidth. FTS driven by electromagnetic force is discussed. The analysis of the magnetic circuit, the requirements of the system and the corresponding design parameters are studied. The designed FTS can realize the bandwidth of 0-100kHz with a special designed driver.

Abstract: The purpose of this paper is to optimize the structural sizes of multi-layer rectangle micro-channel heat sink, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n₁ and that in height n₂ are 21 and 7, the width of optimized micro-channel W_c and fin W_f are 340 and 130μm, the height of optimized micro-channel H_c is 415μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.3354 °C/W. The corresponding pressure drop is about 1.3377 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

Abstract: There is a huge amount of coal mine ventilation air methane emitted into the atmosphere directly each year in china, not only causes a lot of energy was wasted, but also do severe harm to the protection of the environment. The Utilization Technologies of coal mine ventilation air methane (VAM) are receiving more and more attention from people, Aiming at the domestic and international development status of VAM utilization, Thermal flow reversal reactor (TFRR) and catalytic flow reversal reactor (CFRR) are introduced, as two kind of flow-reversal oxidation technology which are the most popular and used widely. The economic and applicability about service life, total cost, space and performance of device are comparative analyzed, and illustrate the trends about the technology of flow-reversal oxidation of VAM from two aspects: to solve the problem of running stability well and improve its work efficiency reasonably. Finally, this paper outlines the future prospect for the development of this technology.

Abstract: As international oil price rise rapidly, the proportion of the fuel cost share of the transport cost has become increasingly high. At the same time, in order to reduce CO₂ emission, the meeting of MPEC formulated and adopted the resolution on EEDI, so saving energy and reducing emission has become a marine industry benchmark. In this paper, through the study on marine diesel engine waste heat recovery system with multi-stage flash, establishing the universal model of multi-stage flash unit, and optimizing the parameters of the low-temperature waste heat recovery system with multi-stage flash. This paper constructs the power equation in matrix model, and each matrix of the model has a simple rule to be filled in, which make it versatile, and suitable for computerization, through estimating the power generation and CO₂ emission reduction of the system on main diesel engine different loads, analyzing the waste heat recovery system with economic method finally.

Abstract: During high-power laser welding process, the workpiece produces metal vapor because of the laser irradiation. The characteristics of metal vapor are related to the quality and stability of welding and the utilization of the laser power. An approach of analyzing the characteristics of metal vapor was researched during high-power disk laser bead-on-plate welding of Type 304 austenitic stainless steel plates at a continuous wave laser power of 10 kW. A high-speed photography was used to capture metal vapor dynamic images. Metal vapor area, beam path, swing angle are calculated by image processing, which is the foundation for monitoring and control of welding quality in real time.

Abstract: Spontaneous combustion of coal is one of the most serious coal mine disasters, which threat the workers' life safety. The paper introduce the comprehensive measures, such as monitor, positive draft technology, nitrogen injection, slip casting, fire preventing and extinguishing under seal, and other relevant coal spontaneous combustion forecast technique used in 1901s fully mechanized workface of FuCheng mining industry, when it has not been mined or its work face has not been removed, which realize the comprehensive treatment of coal spontaneous combustion, guarantee the safe production, and serves as a certain guidance and reference to the efficiency mining of spontaneous combustion coal seam.

Abstract: In this study, pressure drop across a novel CFB riser integrated with an enlarged bottom section was investigated under various operating conditions. Experimental results indicated that total pressure drop was much higher across the riser with larger diameter-enlarged section dimensions, consequently, resulting in lower solids circulation rate realizable in the riser. Based on the measured pressure drop across this novel riser, apparent solids concentrations of the diameter-enlarged section and the conveying section were obtained. Furthermore, empirical correlations for estimating overall average solids concentration in these two sections were established, respectively. And a satisfactory agreement between predictions and experimental results was observed.

Abstract: A 3D finite element model was established to simulate the top surface temperature evolution of Ti45Al8Nb (at.%) alloy ingot under the effect of plasma arc behavior during plasma arc cold hearth melting (PAM) process. According to the model, the top surface temperature distribution and its evolution was analyzed under different heat flux densities. Simulation results show that the position of maximum top surface temperature changes with plasma arc motion, and always located in the plasma arc heating regional center, and it increases first with time elapse and then decreases in the rest of time within one cycle. The results also show that the top surface temperature is increased with the increase in heat flux densities, but the extent is not significant, and meanwhile the temperature distribution is more non-uniform and temperature gradient is greater with the increase in heat flux densities.