Abstract:In order to control the mechanical properties of heavy forgings, it is important to control the grain size of material. The characteristics of the austenite grain size of A5083 steel under different deformation conditions, at different temperature and holding time are studied by high temperature compression experiments and heating & holding experiments. The compression experiments are carried out at 1 050 ℃ and 1 200 ℃ to a strain of 10%, 20%, 30%, 50%, at the same strain rate of 1×10-3s-1. The compression experiments results show that the grain size grade (GB63941986) increases by one level when the deformation is less than 30%, and increases by two levels when the deformation is more than 50% at the temperature of 1 050 ℃. The grain size grade increases by one level when the deformation is less than 50% at 1 200 ℃. The heating & holding experiments results showe that the grain size will not change significantly by two hours’ holding at 1 050 ℃, and changed little by one hour’s holding at 1 200 ℃.

Abstract:A mathematical model for accurate relief grinding of gear hob cutters along radial directions is presented based on the analysis of grinding geometry. Both the design and manufacturing models of gear hob cutters are carefully derived and presented. By employing the plane envelope theory, the reference contour of the grinding wheel is determined in order to attain the design tool profile precisely. The tooth profile error model after regrinding is also given to confirm the grinding parameters. The model provides accurate solutions for both the tool profile and the sectional contour of the grinding wheel. It is simple and straightforward and can be used to produce highprecision hob cutters systematically. Two numerical examples are presented to illustrate the effectiveness of the proposed method. The model computing results indicate that the proposed method is practical, precise and reliable. The method provides valuable reference for the design and machining of hob cutters.

Abstract:A novel modal parameter identification method based on stratified sampling and optimism complex Morlet wavelet is proposed for short data sequences. Stratified sampling is applied to divide the structure response signal into different layers which called subsamples with different thresholds, and then free decrement response signal of each layer is extracted by random decrement technique. The optimism complex Morlet wavelet transform is applied to identify modal parameter of each layer, and the weight of the layer is also determined based on the sample standard deviation. The modal parameter of the structure can be obtained by weighted calculation.The engineering application shows that the proposed method has the ability to identify modal parameter accurately, decouple lowfrequency intensive modal composition and restrain highfrequency fake modal effectively.

Abstract:For the drawback of the power regulation in the existing current fed CPT system, a novel circuit topology and control method is presented, which can realize either Buck or Boost mode and can extend the power regulation scope. The improved topology is modeled, while the relations between the duty cycle and the output power for the two modes are derived for system analysis and design. Simulink and PLECS are used to simulate the PP type CPT system. The simulation results prove the theory analysis.

Abstract:The drawing process of the front side panel of autobody is simulated by using the finite element software, Dynaform. The drawing surface is designed, focusing on the optimization of the addendum and the drawbead layout. By comparing the stress/strain conditions and the FLD in two types of addendum (stepped and slope) and three types of drawbead layout (closed, discontinuous and oblique drawbead), the slope addendum is chosen as the optimized addendum and the oblique drawbead is chosen as the optimized drawbead layout. The simulation results show the material flow in the corner and the quality of the part can be improved effectively with the optimized drawing surface. The optimized parameters are employed in production and acceptable quality parts are produced. Therefore, the optimized drawing surface is verified to be effective.

Abstract:The absorption of uranium by ionexchange resin is studied based on the characters of pregnant solution for a new uranium insitu leaching mine. The resin types, the absorption parameters and the eluting parameters are chosen in the experiments. The results showd that the 201×7 strong alkaline anion exchange resin and TSF2 anion exchange resin had good absorption and eluting effects. The fixed bed anion exchange absorption is a suitable technology and NH4NO3＋HNO3 mixed solution is an appropriate eluting reagent for this technology.

Abstract:This study uses the linear stability analysis to understand the transition characteristics of thermocapillary convection in an annular pool with low Prandtl number (Pr=0.011) fluid. The annular pool is heated from the outer cylindrical wall and cooled at the inner wall. The bottom and top surfaces are adiabatic. The results show that with the increase of the aspect ratio, the critical Marangoni number and the critical wave number decrease. When the aspect ratio exceeds 0.12, the critical wave number keeps almost constant. With the increase of the radius ratio, the critical Marangoni number decreases slightly, while the critical wave number increases.

Abstract:In order to intensify the process of methanol steam reforming, this paper studies the effect of equally and gradiently distributed catalytic bed on methanol conversion and H2 content at reactor outlet. With the application of general finite reaction rate model in CFD software of FLUENT,2D simulation of this process is carried out.The results show that methanol conversion and outlet H2 content can be increased through gradiently distributed catalytic bed with higher catalytic activity at inlets and lower at outlets. Compared with the equally distributed catalytic bed, the cold spot temperature difference in the microreactor reduces by 10 K, experiment results prove that H2 content at outlets increases about 8.5% and CO decreases by about 0.19%.

Abstract:Withmandrel drawing process and the mechanisms of smoothing deformation have been analyzed. A method of smoothing deformation is brought forward that rectangular tube should be extruded uniformity out of die land with little amount of deformation. The dynamics model simplified and FE model of withmandrel drawing process are established based on FEM software, then simulations are performed. Three points including the center of long side, the center of short side, and the center of corner are positioned for further analysis. As for lineartype and steptype mandrel lands, the effective plastic strain and contact stress of three key points are evaluated. As for the plastic strain at the center of long side, a most difficult place to ensure surface quality, steptype mandrel land can improve 45.5%. As for the contact stress, steptype mandrel land can increase to 13MPa from 0. Drawing with steptype mandrel land achieves the stress status tensile stress in one orientation and compressive stress in other two orientations, which purposes of little amount of deformation to correct thickness tolerance and improve inner and outer surface quality of rectangular tube.

Abstract:Based on the status of CBM (Condition Based Maintenance) in domestic and abroad, the authors propose a GSDM (Grey Situation DecisionMaking) method of CBM strategy for power transformers. The countermeasure set of CBM for power transformers includes the five typical maintenance schemes, such as the offline maintenance, priority plan overhaul, surveillant operation, periodic overhaul and postponed overhaul. Taking the safety and economy into account, the five qualitative evaluation indexes of decision making, such as security, reliability, maintainability, economy and monitoring feasibility, are proposed, and the quantitative method of the qualitative evaluation indexes is presented. Through constructing situation effect vectors of GSDM, the optimal maintenance strategy for power transformers can be obtained on the base of the grey relational grade between the situation effect vectors and the optimal situation effect vectors. The examples of the CBM scheme for two power transformers in service are provided to illustrate the specific process of the decision making method and to verify its effectiveness.

Abstract:In order to overcome low sensitivity of the protection based on transient components when the faulty voltage passes zero, regarding arc suppression coill branch as a healthy feeder line, using the relation of its transient energy and all feeders of transient energy amounting to zero, this paper presents an improved fault line selection method in arc suppression coils system using transient energy. This method has no requirements of detection fault close angle and presetting, has a good antiinterference ability and adaptability to various faults occurred in the systems with arc suppression coils. Large amount of digital simulation results show that the proposed method is effective and reliable.

Abstract:Spherical titania is successfully prepared from industrial titanium sulfate solution by hydrolysis method. Effects of the PVP concentration, pH values and hydrolysis time on morphology of Titania are studied. The results show that the optimum PVP concentration, relatively high line pH and certain hydrolysis time are necessary to prepare spherical titania in the mixed solvent of 1propanol and deionized water.

Abstract:This paper conducts the experimental study on the performance of steamwater twophase flow device composed by a nozzle,mixing chamber and the corresponding valves when the inlet steam pressure is in the range of 0.18~0.22 MPa．The experimental results show that the injector can run stably and reliably and the temperature of outlet water is increased obviously in low inlet steam pressure．This characteristics can be used as effective heaters in the engineering fields such as power plants,heating,the light industry, etc． When a singlestage ejector can not meet the requirements of heating conditions, doublestage ejectors can be used.

Abstract:This study conducts nonisothermal combustion experiments of three types of pulverized coal by Synthesized Thermogravimetry Analyzer in O2/N2 and O2/CO2 atmospheres. It analyzes the changes of combustion characteristic parameters of pulverized coals in different atmospheres and calculated the kinetic parameters at each condition. The results show that combustion characteristics under O2/CO2 atmosphere are different from those under O2/N2 atmosphere at the same O2 concentration. When N2 is replaced by CO2, both ignition time and burnout time of pulverized coals increase, burnout temperature is higher, and combustion characteristic index declines. DTG curves of coal combustion move to low temperature zones when O2 concentration in O2/CO2 mixture increases. It indicates that both ignition and burnout temperature are lower, burnout time decreases, combustion characteristic index obviously increases, and combustion performance of pulverized coals are improved. Activation energy, frequency factor and reaction order at lowtemperature stage are lower than those at hightemperature stage. Kinetic compensation relationship exists between combustion activation energy and frequency factor in different atmospheres.

Abstract:This paper studies the effect of styrene divinyl benzene (SDB) solid phase extraction (SPE) and graphitized carbon black (GCB) SPE on the quantification of estradiol (E2) and ethinyl estradiol (EE2) by enzymelinked immunosorbent assay (ELISA) kit. The recovery rates of E2 and EE2 in spiked raw sewage samples drop from 181.4% and 122.6% to 113.3% and 109.4% respectively with the relative standard deviations dropped to below 10.0%. The reovery rate of E2 in final effluent decreases from 144.2% to 93.5% whilst the rate of EE2 has marginal variation, and the relative standard deviation drops from approximately 10.0% to lower than 8.0%. The estrogen levels measured by ELISA are collated with those measured by parellel liquid chromatrography coupled with time of flight mass spectrometry (HPLCMS(TOF)). GCB SPE with step elution is able to separate E2 and EE2 from the matrices thus reduces the cross reaction rate. GCB SPE decreases 38% and 15% false positives for E2 and EE2 ELISA analysis compared with SDB SPE. ELISA quantification with this improved GCB SPE pretreatment has the advantages of low cost and timesaving over the chemical analysis.

Abstract:The paper concludes the characters of methanol as a fuel in engines. Based on the kiva3v program, it conducts the multidimensional numerical simulation of the operation process in cylinder of a methanolfueled engine to obtain the detail information and performance graphic charts, as well as the real time data of pressure, temperature and so on. It is helpful for the research on methanolfueled engines. The results indicate that the methanol is a green alternative fuel and the methanolfueled engines have steady operations and lower emissions by comparing the numerical results with the data of gasoline engine.

Abstract:To reduce the noise signal in the sampled data of the Electronic nose(enose), an improved adaptive method based on Kalman filtering algorithm is presented, which can adaptively adjust measurement error variance, while denoise the NonGaussian noise in an enose output. A Kalman filtering model for measurement data processing is introduced based on the signal characteristics in the enose measurement processing. The improved adaptive filtering method is discussed in detail and applied to enose signal processing. The results demonstrate that the proposed method can adaptively reduce the noise signal in the enose measurement data processing and improve the sensitivity of enose measurement.

Abstract:In order to achieve optimal bidding strategy of power plants in electricity market, the authors build optimal bidding model by predicting the bidding coefficients of competitors, and the optimal bidding coefficient without considering transmission capacity is achieved. Based on the bidding coefficients, the market clearing model is built, and the expected market clearing price is achieved. According to the expected values, the authors calculate the power flow. When forecasting the transmission congestion, this paper presents an optimal bidding model taking transmission congestion into account. Based on sensitivity analysis, the output regulation of power plants with minimum cost of eliminating congestion is achieved. Simulation results demonstrate that the proposed method can help power plants achieve the optimal profit.

Abstract:In order to improve image corner detection precision and efficiency, a novel corner detection algorithm based on Bspline scale space evolution difference is proposed. The norm of DoB is defined as corner response function to evaluate the multiscale evolution difference. The DoB corner detector confluents the image boundary features with different scales, which can not only strengthen the response of the feature points, but also depress the influence of noise. Among all corner detection algorithms based on BSpline, the proposed algorithm is relatively lower for computation complexity and faster. The comparative experiments demonstrate that the proposed algorithm works well for localization, robustness against noise, as well as invariance to rotation and scalability.

Abstract:By analyzing the reason that why the existing routing protocols cannot be applied to the wireless sensor networks for bridge health monitoring, a new routing protocol is proposed. Since the locations of the collecting modules are fixed, the proposed protocol exchanges the routing information between the neighbor nodes by adjusting the exchange cycle according to reliability of the modules. For the low routing security requirement, while to increase the routing efficient, the middle nodes replying the routing requirements with variable thresholds is introduced. In order to make full use of information in route discovering procedure, the backup routes mechanism is adopted. The proposed protocol can efficiently forward data and is suitable for the bridge health monitoring.

Abstract:The mathematical model of vacancy course path optimization of laser machining is built and changed to the travelling salesman problem (TSP). The Nearest Neighbor (NN) is modified to Adaptive Neighborhood Method (ANM). In ANM one mimics the traveller whose rule of thumb is not always to go next to the nearest asyetunvisited location. The next city is randomly selected from the unvisited cities in adaptive neighborhood. While solving the TSP, ANM is used to create the initial population at first, then iterations are done through selection, cross and mutation operation. In selection, the proposed algorithm only keep 90% samples from the previous generation, the remained agents are supplied by the new sample created by ANM. The results show that the algorithm shortens vacancy course in laser machining and the manufacturing efficiency is improved.

Abstract:For cylindricity error evaluation, the Least Squares Method (LSM) is not good enough because of the big error, while the bionics algorithms such as Genetic and Ant Colony Algorithm need to set many parameters and converge slowly, an Artificial Bee Colony Optimization Algorithm is proposed to evaluate the minimum zone cylinder (MIC). This Algorithm refers the tabu strategy for tabu search algorithm to use the Tabu table to save the local optimization results. It enhances the control effect of parameter limit and improves the global convergence ability. Experiment results indicate that this method can converge to the global optimization very quickly. The average runtime is nearly 1.2 s. It is applicable to the realtime processing system such as ThreeCoordinate Measuring Machine.

Abstract:For the limitations of the traditional monitoring systems under the circumstances of dispersed monitoring points, wide distribution range and the harsh environment, a distributed wireless monitoring system based on radiofrequency technique is designed. The system adopts the ultralow power consumption MCU MSP430 as the main control chip and extends several processing module in the periphery. In addition, the multichannel transceiver nRF905 is used for wireless data transmission. The software and hardware design scheme of the proposed system and the communication protocol for distributed data transmission are discussed. Frequency hopping mechanisms are employed to increase the reliability of data transmission. The results show that the proposed system has the characteristics such as flexible use and excellent mobility, while can monitor multipoint data in special environment in realtime.