Abstract:An elastoplastic finite element method (FEM) was used to study the deforming mechanisms of an aluminum tube drawn without a mandrel from a circular to a rectangular crosssection. The simplified dynamics model and FE model of the nonmandrel drawing process were established based on the FEM software deform3D and simulations subsequently performed. Based on the simulation results, the influence of different semidie angles on the drawing load was summarized, and the proper values were found. As for the blank instability during the drawing process, the tangential stress distribution rule along the rectangle sides was acquired. The drawing die sizing section then was modified with a camber angle of 178° to eliminate instability. The touch boundary and touchstress distribution during drawing process also were analyzed. The aluminum tube produced by the optimized drawing die possesses eligible dimensions and smooth inner surfaces.

Abstract:A highly efficient precision grinding method was proposed for the development of typical freeform surfaces such as turbine blades. A sixaxis simultaneous grinding and polishing machine was created. The machine can polish freeform surfaces with abrasive belt grinding technology by computer numberical control(CNC). The key techniques to develop this new grinding machine are presented in detail, including multiple axes rotary spindle grinding head, NC grinding computer aided software, cooling, a scrap removal device, and other features. The experiments of grinding and polishing turbine blades were performed based on different parameters. This research provided sufficient data to confirm reasonable belt grinding and polishing parameters. 

Abstract:To solve the key problems of the electric drive system, a controller area network(CAN)based electric drive system for electric vehicles was designed. The system was composed of two parts: a CAN communication module and a motor control module. The newest transceiver (TJA1040) and a standalone CAN controller were used during the design of the CAN communication module, and antijamming measures were employed to guarantee communication stability. The fuzzyvector control method and direct speed control were applied to realize highly robust control functions. This system has high compatibility. It can be installed in electric vehicles as an independent module and be extended through CAN Bus. 

Abstract:A finite element model of a piston and a block surface was established. After boundary and work conditions were applied, an initial transient analysis of the model was carried out. The simulation result of vibration acceleration on the block surface conformed well with the experiment, thus validating the model. Based on the model, the motion law of pistons in blocks was studied. The variation trend of the piston slap force, piston clearance on the piston slap force, and the effect of piston pin offset on the piston slap force at different crankshaft speeds were analyzed. Results show that suitable piston pin offset and smaller piston clearance reduce the piston slap force quite well; and the contribution of the piston force at the point when gas breaks out is dominant at low speed, which is not obvious at high speed. The findings provide evidence for the performance improvement of internal combustion engine development. 

Abstract:The traditional small univalue segment assimilating nucleus (SUSAN) operator may confuse the corner and the edge. An improved SUSAN subpixel operator with high speed and high position accuracy was proposed. According to the characteristics of the SUSAN template, the gray symmetry degree was defined to distinguish the corner from the edge. Sobel operator and gray square centrobaric arithmetic were synthesized with the improved SUSAN operator in subpixel corner detection. In the camera calibration experiments, this method proved to be rapid and efficient, and the improved operator’s average reprojection error was less than 0.2 pixels.

Abstract:Using a computer, the structure of a grating light valve (GLV) was simulated based on analysis of optics characteristic of a GLV. Driven by the electrostatic force, the GLV has high optical efficiency and high switching speed. These traits were used to design a 1×2 microelectromechanical systems (MEMS) optical switch in order to improve upon the traditional MEMS optical switch’s shortcomings, such as easy wear, slow switching times, and short switching lives. The simulation experiment using CoventorWare shows the firstorder diffraction efficiency achieves 50% and the switching time is at microsecond level when the 1.55 μm light wave length is in normal incidence and the given parameters of GLV are assigned.

Abstract:In order to understand the basic characteristics of the heat transfer of natural convection of water near the maximum density in a horizontal annulus, twodimensional numerical simulation was conducted using the finite volume method. The outer wall temperature was maintained at 0 ℃, and the temperature of inner wall at 1 ℃ to 10 ℃. The results show that the heat transfer coefficient at the inner wall first decreases with increased annulus width, then increases, and then constantly decreases with the increased inner radius in the region of calculation. When the temperature difference is below 4 ℃, the heat transfer coefficient increases with increasing temperature difference. When the temperature difference exceeds 4 ℃, it decreases with the increase of the temperature difference. Finally, the formula of heat transfer at the inner wall was obtained by using stepwise linear regression.

Abstract:In order to design the reduction furnace reasonably, the heat convection coefficient between the cooling water and the water pipe in the cooling module, and the comprehensive heat transfer coefficient of the exterior furnace shell were calculated using engineering heat transfer analysis. Based on the workflow of a reduction furnace, three work conditions were defined. Using finite element software ANSYS, the furnace shell temperature field and the thermalstructure coupled stress field in high temperature working conditions were calculated using a thermalstructure coupled method. The result indicates that the maximum Von mises stress of each region of the furnace shell is significantly less than the yield limit of the material under the workload. The static strength of the furnace shell satisfies the practical requirements. The GoodmanSmith fatigue limit figure was used to evaluate each node. It was found that the fatigue strength also meets the corresponding requirements.

Abstract:We conducted an experimental study of heat pipe rotating about parallel axes. The entire pinfin of noncontact thermal resistance was used in the cooling section of the heat pipes. The experimental liquidfilled volume range from 10% to 25%, and heat flux density range was 7×103W/m2 to 5.3×104 W/m2. A cooling current of air was formed by the heat pipe rotation. The Reynolds number range was 2.3×103 to 1.2×104. The experimental results indicate that the heat transfer performance of the heat pipe was the best when liquidfilled volume reached 20%. The heat transfer capability strengthened gradually along with the increasing rotational speed. The change of the heat power had little impact on the heat transfer performance of the heat pipe. It was found that the absorption liquid core was of little use to the heat transfer performance of the heat pipe. Under the same conditions, the heat transfer performance of the parallel rotating heat pipe was 1.5 times that of coaxial rotating heat pipe.

Abstract:Three typical commercial buildings in Chongqing, P.R. China were selected to study the actual summertime operation and energy situations of heating ventilating and airconditioning (HVAC) systems in commercial buildings. Based on tests of energy consumption of HVAC systems in these three buildings, we analyzed the electricity consumption of the main components of the airconditioning systems. The energy efficiency of the chillers and airconditioning water distribution systems were studied. The indoor thermal environment in these three buildings were also tested and discussed. It is concluded that problems exist in the airconditioning systems of commercial buildings. Among the problems are oversized system design, low equipment operating efficiencies, poor operation management, and lack of indoor temperature controls. To reduce energy consumption of HVAC systems in commercial buildings, we propose energyefficient strategies such as sizing systems based on accurate load calculation and automatic control under partialload conditions.

Abstract:Methods of IF difference detection combined with rapid acquisition synchronization and tracking principle by parallel processing methods were proposed in order to quickly achieve synchronous digital capture and tracking in π/4DQPSK demodulation.Field program grid array (FPGA) technology to achieve rapid detection of synchronous capture and symbol tracking was adopted by using the improved algorithm in parallel with signal acquisition and frequency offset acquisition. This adoption took into account the characteristics of π/4DQPSK and was in accordance with the detection of rapid acquisition synchronization and the tracking principle. The experimental results show that clock synchronization signals can be restored stably in eight symbol bit, accurately realize bittiming, and possess strong antiinterference capability without affecting frequency differences. This proposed algorithm is suited for frequency hopping communication systems with high transmission rates.

Abstract:From the view of trick recognition, features of signal decomposition structure in existing frequency estimation methods were analyzed, based on which, a frequencyshiftdomain decomposition structure was proposed. A compound signal was constructed by combining several simple signals corresponding to different times. The given information in the time domain can be adopted to form an information accumulation effect, such that the interference frequency and noise can be suppressed effectively by decreasing the calculation. To match the use of a frequencyshiftdomain decomposition structure, a frequencyshift equilong iterative algorithm suitable for equilong signals was proposed. Simulated experiments were carried out in numerous application environments. The results show better noise immunity and realtime performance as well as higher frequency estimation precision.

Abstract:Fullscale data mining, such as in cluster problems, requires large numbers of computations. A parallel cluster algorithm for selfadaptive particle swarm optimization was proposed to deal with this problem. The proposed parallel particle swarm optimization algorithm reduced the impact of the initial conditions via parallel searches of the globally best position amongst a varied population. Task parallelization and partially asynchronous communication of the algorithm were employed to decrease computing time. Furthermore, if combined with the characteristics of selfadaptive and dynamical optimization parameters of the parallel particle swarm algorithm, the problems of particle mobility loss and the end of evolution could be dealt with successfully. When modified thusly, the algorithm maintains individual diversity and restrains degeneration. The simulation experiments indicate the algorithm helps increase computing speed and improve cluster quality.

Abstract:An efficient and accurate metadataoriented prefetching scheme is critical for achieving the best metadata service performance in large distributed storage systems. Most previously developed algorithms, however, do not consider the characteristics of metadata, such as small size. In light of this issue, we presented a 3gram based model and datamining technique to use the traces of metadata accessing to prefetch groups of users’ future metadata operations. By using large tracedriven simulations in which our new prefetching scheme was adopted, it is shown that the hit rate for metadata access extracted from the traces can be increased by up to 3.9% and 16 % compared with NEXUS and least recently used(LRU), respectively.

Abstract:Based on the influence of ultrasonic vibration on the adsorption/desorption and seepage characteristics of coalbed gas, a test system for the measurement of adsorption and seepage characteristics of coalbed gas was designed. The main component of the system is a pressure testing device. The test system consists of six parts, including an intelligentized acoustic generator, adsorption and seepage devices, a pressure supply, a deformation measurement component, a gas supply and a deformation tester. The function and operating method of the test system were introduced in detail. Experimental results show that the test system can meet completely the requirements for the characterization of adsorption/desorption and seepage of coalbed gas in either the presence or absence of an ultrasonic field.

Abstract:An acoustic emission (AE) location experiment was performed on sandstone using an advanced AE test system. The spacetime evolution rule regarding damage was analyzed under cyclic loading as well as AE. The results show that: AE on static loading process is consistent with the damage evolution rule of compression and the elasticplastic deformation phase;At the beginning of cyclic loading with low duration time and energy, AE events came from a small crack. The location result showed that most events occurred in the core zone forming at the static loading process and the location points changed slowly. AE energy changed little during the metaphase of the cyclic process. There was a modest increase of location points in every cycle. The tendency of steady development could be predicted from the AE location events. At the end of each cyclic loading, the quantity of AE events and energy increased rapidly, reaching a maximum at the last cycle. AE events had high energy and duration time. Location events changed quite rapidly, and assembled and linked continuously in the core zone. At the same time, they expanded to the top of specimen. A macroscopic crack finally formed. In the postfailure process, some AE events still existed due to fracturing of gliding friction. Owing to the inner stress balance of rock even after loading stopped, minor AE events still occurred. 

Abstract:A slope geomechanical model was proposed based on the destabilization characteristics of soft sandwichrock slopes. Based on an analysis of the effects of internalexternal factors on slope stability, the cusp catastrophe model of slopes can be employed to analyze and predict the necessary conditions leading to slope catastrophes. During the processing of the mass and energy exchange with the external, this may lead to the change of controlling variables. Slides or quick or slow creeping thus may take place due to environmental complexity. This work helps deepen understanding of the formation of landslides and makes feasible the applcation of the catastrophe model to slope destabilization investigations.

Abstract:A fixedfilm system composed of an anaerobic biofilter and an intermittently aerated biofilter (IABF) was developed for enhanced biological phosphorus removal (EBPR) in the treatment of domestic wastewater. We investigated the influence of the operating regime on the performance of EBPR in IABF. Compared to the sequencing batch regime, net phosphorusuptake capacity in IABF was improved under the aerobic continuous feeding (ACF) regime. An innovative method that can be used instead of traditional backwashing was applied to IABF for removal of phosphorus from the reactor under the ACF regime. Using this method, a stable performance of EBPR was achieved during longterm operation, with a low frequency of backwashing in IABF. Distribution and variation of organic and phosphorus in IABF may imply spatial distribution of microorganisms in the column of the reactor under the ACF regime. 

Abstract:The nitrogen removal performance of a constructed rapid infiltration system (CRI) constructed using the common purple soil and sand from the Three Gorges Reservoir Region in the P.R. China was studied. In order to optimize the construction and the nitrogen removal performance of the CRI, three 1.5 m high columns were examined using mixed media with soil/sand ratios of 2∶1, 3∶1 and 4∶1, respectively. Four soil columns with heights of 0.3, 0.6, 1.0,1.5 meters subsequently were tested using media ratio of 3∶1. It is shown that the CRI constructed by the medium of sand/soil ratio being 4∶1 possesses better removal performance for the removal of NH3N, NO3N and TN. The removal rates for NH3N and TN are 71.7% and 48.8% respectively, close to the nitrogen removal performance of unmixed purple soil. Hence the 4∶1 medium of sand/soil ratio is appropriate. It is also shown that, when considering the functional area of CRI treating the sewage, the upper 0.6 m of CRI is the main area that removes COD and NH3N, whilst 0.6 m~1.0 m is the main area that removes TN. Increasing the soil layer thickness does not ensure better nitrogen removal performance. The 1.0 m soil layer thickness of a CRI system is appropriate for treating sewage in the Three Gorges Reservoir Region.

Abstract:Polysilicate metal salt exhibits excellent flocculation ability. Polysilicate aluminum ferric(PSAF) was prepared through copolymerization by sulphates and chlorides of aluminum or iron with polysilicate acid. The optimal hydrolysis parameter of different PSAFs was determined. Differences in turbidity and flocculation function of four types of PSAFs were evaluated. Furthermore, differences in coagulation and phosphorus removal were analyzed and discussed.

Abstract:The effects of temperature, time, inoculating quantity and dosage of cellulose enzyme on the preparation of fuel ethanol from straw stalks by means of the simultaneous saccharification and fermentation method (SSF) were studied. The results show that after pretreating straw stalk by mechanical comminution and sparse sulfuric acid, the optimal fermenting temperature is 38 ℃, the fermenting period is 72 h, the inoculating quantity is 10%, the dosage of cellulose enzyme is 40 IU/g, and the ratio of Pachysolen tannophilu to saccharomyces cerevisiae is 2∶1. The ethanol yield reaches as high as 0.20 g/g.

Abstract:Tafel polarization curve and electrochemical impedance spectroscopy (EIS) techniques were employed to investigate the corrosion behavior of AZ40 magnesium alloy in simulated sea water. The surface morphology of the alloy during exposure was observed with an optical microscope and a scanning electron microscope. The pH variation of bulk solution during corrosion was recorded. The results show that the major corrosin forms of AZ40 magnesium alloy in simulated sea water were characterized by pitting and filliform corrosion. The corrosion occurs spontanesously. The insovable corrosion products, which precip it ate on the alloy surface were characterized by porsity and hetorogeneity, indicating that these products can not prerent further alloy corrosion. Therefore, the corrosion of AZ40 magnesium alloy spreads rapidly and the alloy surface is destroyed severely during short exposure period. 

Abstract:Cobalt phthalocyanine （CoPc）was prepared from phthalodinitrile and cobalt sulfate via microwave irradiation. The Resonance Rayleigh scattering（RRS）was enhnaced by the interaction of sulfonated CoPc and bovine albumin（BA）. An RRS peak formed at 460 nm with intensity proportional to the concentration of BA. A simple and rapid method of RRS for the determination of BA thus was established. The linear range is 0.1 ug/mL to~6.0 ug/mL. The detection limit for BA is 5.73 ng/mL.