Abstract:In order to explore the influence of different flow channel designs on the heat dissipation performance, temperature uniformity and energy consumption of liquid-cooling plates, the Computational Fluid Dynamics(CFD) fluid-solid-heat coupled numerical simulation method is used for investigating the influences of their structural design parameters on the heat dissipation performance of a liquid cooling unit of electric vehicles. The results show that when the width of the central flow channel is increased from 6 mm to 31 mm, the maximum temperature difference on the surface of the thermal conductivty pad is reduced by 19.4%, and the flow resistance is increased by 14.6%，when the width of flow channels is reduced from the middle to both sides, the heat dissipation performance and temperature uniformity can be further improved, and the energy consumption can be controlled within an acceptable range. When the depth of flow channel is decreased from 5 mm to 2 mm, the maximum temperature difference is reduced by 36.7%, but the flow resistance is increased by 3.3 times, reducing the depth of the flow channel can significantly improve the heat dissipation performance and increase the energy consumption. Liquid-cooling plates with enhanced heat transfer structure channel or exchange of inlet and outlet in some cases can improve the heat dissipation and temperature uniformity, and also increase the flow resistance and energy consumption. It is concluded that the structure design of liquid-cooling plates can be supported by this research in order to improve the heat dissipation performance of battery module.

Abstract:In order to investigate the influence of the parameters of the swing-cylinder hydro-pneumatic suspension （HPS） on the “load wheel - suspension - sprung mass” system, a parameter sensitivity analysis on the dynamic response characteristics of the system was conducted under typical working conditions. The mechanical-hydraulic coupled dynamic model was built according to the structural characteristics of the HPS, and then it was verified with the comparison of the results obtained by simulation and experiments from the test rig. The key parameters of the HPS were selected to study their influence on the variation trend of the stiffness and damping characteristics of the suspension, after that their impacts on the dynamic response behavior of the HPS system were investigated under bump excitation. The results show that the stiffness of HPS system is greatly influenced by the initial gas volume of the accumulator when suspension deflection is small，while the position angle of the hydraulic suspension affects most when suspension deflection becomes large at compression travel； the vertical acceleration at the center-of-gravity of the sprung mass and the wheel load are most affected by the initial gas volume of the accumulator at low frequencies and it is most affected by the cross-section area of the damping valve at high frequencies; the suspension deflection is affected by these parameters in a reverse trend.

Abstract:To reduce the pressure shock and oscillation phenomena caused by the hydraulic system in the steering process, and to improve the stability of the steering system, this paper proposes an optimized structure of redirector with by-pass damping. The mathematical model of steering system is established to analyze the influence of load sensing characteristics and by-pass damping on steering stability. The co-simulation model of loader dynamics and hydraulic steering system is established. The accuracy of the simulation model was verified by the test system. The simulation results of the two steering system models with and without by-pass damping are compared. The results show that，compared with the simulation results of the original steering structure, the steering system with the by-pass damper ensures good load sensing characteristics and stability of the system, weakens the peak pressure shock and reduces the pressure oscillation of the hydraulic system.

Abstract:In order to improve the accuracy of outfield sound source identification in automobile wind tunnel, the deviation caused by the difference between actual flow field and empty wind tunnel is analyzed. Focusing on the velocity distribution of flow around vehicle and jet shear layer, numerical simulation and experimental verification were carried out on 3 kinds of flow fields, including free space where vehicle is located, empty wind tunnel and wind tunnel with actual vehicle. The amounts of sound drift in wind tunnel with or without vehicles were predicted by using infinite thin shear layer model and layered flow field sound propagation model. The predicted sound drift quantities were compared with actual full-scale acoustic wind tunnel sound propagation test results. The results show that，after vehicle was placed in the wind tunnel, the flow field velocity distribution in core area of potential flow was uneven due to obstruction of the vehicle, and then the flow field in shear layer was disturbed by flow field around vehicle. After stratified correction of the actual flow field, the accuracy of sound drift quantity at rear sound source of vehicle body is greatly improved, which can effectively improve the identification accuracy of the actual wind tunnel.

Abstract:To address the problems of high heating power consumption and poor heating effect in a low-temperature environment, an air conditioning system of the electric vehicle is proposed to reduce the heating power consumption by recycling motor waste heat for passenger cabin heating. Th motor waste heat circulation system model is established by AMESim software and the accuracy of the model is verified by the motor waste heat heating experiment. Then, the heat pump air conditioning heating system model is established and the accuracy of the model is checked by the heat pump air conditioning heating experiment. Finally, the simulation model of a heat pump air conditioning system with motor waste heat recovery is established, and the performance of motor waste heat and motor waste heat auxiliary heat pump air conditioning is analyzed. The experimental results show that the motor waste heat alone can meet the heating demand under the working condition of medium vehicle speed and ambient temperature above 10 ℃. The motor waste heat-assisted heat pump air conditioner heating can effectively improve the heating efficiency. And the equivalent heating energy efficiency ratio can reach 3.4 under the working conditions of the motor speed of 3 000 r/min, compressor speed of 4 000 r/min and ambient temperature of -5 ℃. Under the same working condition, the equivalent energy efficiency ratio is 48% higher than the energy efficiency ratio of the heat pump air conditioner alone. This system can effectively improve the energy utilization rate of the electric vehicle and the heating performance of the air conditioning system.

Abstract:Conventional fuzzy inference algorithms cannot effectively solve the inverse heat transfer problems with complex or unknown heat transfer laws. In this paper, a feedback-fuzzy inference global method is proposed. Based on the basic process of fuzzy inference, variable universe method, feedback thought and simulated annealing algorithm are combined. The dependence of fuzzy rules on heat transfer law is reduced by feedback unit, and the local optimum is prevented by simulated annealing unit. This method was employed to solve the geometric structural design problem of air-cooled radiator fins. The results were compared with those of conventional fuzzy inference and simulated annealing algorithm. And the results of feedback-fuzzy inference global method under different initial values and input errors were verified and compared. The results showed that the proposed method could solve the inverse heat transfer problem with complicated or unknown heat transfer law, and the results were not affected by initial values. The method demonstrates robustness and resistance to ill-posed problems, which can provide a reference for inverse problems, structural design and optimization.

Abstract:Aiming at the centrifugal tensile stress failure of permanent magnets on the rotor for super high-speed air compressor in high-power fuel cell system, the magnitude of interference between the sleeve and the permanent magnet as well as the stress at the rated speed are calculated by the analytical method. Then, a two-dimensional axisymmetric model was established by the finite element method to calculate the stress distribution, and the accuracy of the analytical method and the finite element method was compared. Furthermore, the influence of temperature rise and sleeve material on stress is studied based on the finite element method. The results show that the calculations of the two methods differ no more than 2.5%. Among the influencing factors, both the rotational speed and the temperature rise cause a significant increase in the stress of the permanent magnet, and it is necessary to increase the interference in order to provide protection for the permanent magnet. Additionally, the carbon fiber sleeve can reduce the stress of the permanent magnet by at least 42.1% when compared with the alloy sleeve, and the effect is particularly obvious under high temperature conditions. Therefore, reducing the rotating speed, increasing the assembly interference and improving rotor cooling can effectively optimize the structural strength, and the composite material sleeve is more suitable for protecting permanent magnets than the steel sleeve.

Abstract:Aiming at the problem that the resonant frequency of a three-parameter vibration isolator with a layer X-shaped structure will move to high frequencies, a new type of n-layer X-shaped structure isolator is proposed. Firstly, the harmonic balance method is used to establish the analytical model of the dynamic response of the new vibration isolation system, and the analytical solution is compared with the simulation data obtained by the time-domain numerical solution and the multi-body dynamics software ADAMS to verify the correctness of the built-up model of the isolator with an n-layer X-shaped structure. Based on the established model, the force transmissibility curves of , as well as the traditional two-parameter vibration isolator, traditional three-parameter vibration isolator, and a layer X-shaped structure vibration isolator, are calculated and compared. It is concluded that the proposed vibration isolator with n-layer X-shaped structure can further reduce the peak at resonance, and the resonance frequency ratio moves to lower frequency region. At the same time, the main parameters that affect the performance of the X-shaped structure with n-layers are the damping ratios, the initial angle, the stiffness ratios, which are independent of the excitation force amplitude and the rod length. Furthermore, the influence of the damping ratios，the initial angle and the stiffness ratios on the transmission characteristics of the vibration isolation system is further analyzed. The peak at resonance frequency of the vibration isolator with an n-layer X-shaped structure is further reduced when choosing proper design parameters around the resonance frequency, while the dynamic performance is not changed in high-frequency region.

Abstract:In order to explore the mechanism of positive rake angle (PRA) grinding for diamond grit and to demonstrate the feasibility of PRA grinding, the finite element simulation software ABAQUS was used to establish a grinding model of Ti6Al4V titanium alloy with single diamond grit. Then, the change law of grinding force in the grinding process of single diamond grit with PRA or negative rake angle under different process parameters was studied and compared. On this basis, titanium alloy grinding experiments were carried out for the PRA diamond grit fabricated by femtosecond laser and the original negative rake angle diamond grit. The grinding force was measured by the dynamometer and compared with the simulation results. The grinding surface morphology was observed, and surface roughness was measured. Furthermore, the grinding force，grinding surface morphology and surface roughness between PRA and negative rake angle grinding were compared. The results show that，in single diamond grit grinding, the grinding force decreases with the increase of grinding speed, increases with the increase of grinding depth, and decreases gradually as the rake angle varies from negative to positive. And the trends of grinding force obtained by simulation are basically consistent with the experimental results. Compared with the traditional negative rake angle grinding, the PRA diamond grit also has good wear resistance, and the grinding surface with PRA diamond grit has the advantages of shallow grinding traces, fewer machining defects, and the surface roughness is reduced by 58%~66%, which can effectively improve the surface quality of grinding.

Abstract:Aiming at the shortcomings of slow convergence speed, unsmooth path and easy to fall into local optimum in Ant Colony System(ACS) algorithm, an ACS algorithm based on gravitational search strategy is proposed. Firstly, in order to solve the problem that the lack of map information in the initial stage of the algorithm leads to the great blindness problem of ant colony algorithm, a simplified ant colony algorithm is proposed to update the initial pheromone concentration; secondly, the search strategy of gravity algorithm is introduced to improve the speed of the later algorithm and effectively solve the local optimal problem; finally, the optimal path obtained by each iteration is optimized, which reduces the number of turning points and improves the smoothness of the path. Simulation results show that the improved algorithm can effectively improve the convergence speed and path smoothness of the algorithm. Additionally, the improved algorithm is applied to the actual mobile robot navigation experiment. The experimental results show that the improved algorithm can effectively solve the path planning problem of mobile robot, and effectively improve the efficiency of robot navigation.

Abstract:Dendritic polyaniline, long fibrous polyaniline, dendritic polyaniline/graphene and long fibrous polyaniline/nitrogen-doped graphene aerogels are employed as precursors to produce nitrogen-doped continuous nanocarbons through direct carbonization. The microstructure, element composition, and electrochemical properties of polyaniline-based aerogels derived nanocarbons are systematically investigated. The results show that nanocarbons derived from dendritic polyaniline, long fibrous polyaniline, dendritic polyaniline/graphene and long fibrous polyaniline/nitrogen-doped graphene aerogels have a continuous hierarchical porous structure, high specific surface area of 273.9, 487.7, 241.4 and 295.9 m2·g-1, respectively, high nitrogen molar fraction of 7.82%, 9.62%, 7.91% and 10.17%, respectively, and high specific gravimetric capacitance of 268, 311, 280 and 362 F·g-1 at the current density of 0.5 A·g-1, respectively, as well as excellent rate capability and cycle stability.

Abstract:In this study, a simple two-step strategy of self-assembly method is used to fabricate the graphene-based polyaniline composite hydrogel (PR-x) which attains a three-dimensional porous network structure. The microscopic morphology and structure composition are characterized and analyzed by SEM, XRD, FT-IR, Raman, XPS and other characterization methods. The results show that polyaniline (PANI) is uniformly distributed on the framework of three-dimensional porous graphene network, which can significantly inhibit the agglomeration of graphene. In addition, the electrochemical performance of graphene-based polyaniline composite hydrogel electrodes as supercapacitor is systematically studied. When the PANI content is high up to 75%, the specific capacitance is found to be as high as 762.8 F·g-1 at the current density of 1 A·g-1. Likewise, the specific capacitance retention rate is still as high as 77% when the scan rate increases from 5 mV·s-1 to 50 mV·s-1, meanwhile, the cycling stability is high up to 89.27% even after 3 000 cycles. The graphene-based polyaniline composite hydrogel electrode as a supercapacitor exhibits high specific capacity, excellent rate and cycling stability, providing the potential supercapacitor application.

Abstract:Waste phenolic resin was employed to prepare a composite adsorptive carbon material via the pyrolysis method. Co（NO3）2 doping amount was set to be 0.75%, 1.0%, 1.5%, and the pyrolysis temperature 700 ℃, 900 ℃, 1 100 ℃, respectively. Morphology and formation mechanism of the material were investigated by means of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). X-ray diffractometer (XRD) and Raman spectroscopy were used to explore the effect of catalyst amount and pyrolysis temperature on the formation of carbon nanotubes. BET surface area test method and BJH model were employed to calculate specific surface area and average pore size. The magnetic test and Zeta potential were used to characterize the magnetic separation of the material and the stability under different pH. The adsorption and removal efficiencies of material with different doping levels for Bisphenol A (BPA) were compared with those of commercial carbon nanotubes. And the adsorption isotherms of Langmuir and Freundlich models were used to fit the adsorption data to explore the adsorption mechanism. The results showed that carbon nanotubes were uniformly generated on the surface of the material, with cobalt oxides inside the carbon tubes and at the ends. The specific surface area of the material was 290.74 m2/g and the average pore diameter was only 3.63 nm. Adsorption equilibrium could be reached within 6 hours and the adsorption process was more consistent with the Freundlich model, indicating that there were different types of active adsorption sites on the surface of the material, and adsorption occurred at a complex heterogeneous interface. The maximum adsorption capacity was 53.19 mg/g.

Abstract:The light-weight aggregate concrete was prepared with common Portland cement, shale ceramsite, polypropylene fiber, foaming agent and other additives. The characteristics of sound absorption in the low and medium frequency range for the cement content, fiber, grain size of shale ceramsite, foaming agent, ceramsite test block, different types of ceramsite test block and series connection were studied. The results show that the single-grain shale ceramsite concrete has good sound absorption performance near 600 Hz frequency band. When preparing concrete, adding fiber and foaming agent (H2O2) can improve the internal structure of the material, which is conducive for improving the sound absorption performance of the material. The overall sound absorption performance of the series structure of ceramsite concrete test blocks with different particle sizes can be improved by nearly 80% when compared with the original test blocks.

Abstract:Taking the friction stir welded joints of 3 mm thickness 6061-T6 aluminum alloy plate as the research object, a thermal mechanical coupling finite element model was established to accurately simulate the temperature filed distribution and evolution law of the welding process. The influence of different welding speeds on forming characteristics, microstructure and mechanical properties of the joints was studied by using optical microscopy, electron backscatter diffraction, microhardness measurement and tensile test. The results show that a completely dynamic recrystallization process occurs in the nugget zone during the welding process, which generates fine equiaxed grains, whereas the heat-affected zone (HAZ) on the retreating side undergoes dynamic recovery, resulting in the obvious grain growth. It is also found that the strengthening effect of grain boundary in the HAZ is weaker than that in the nugget zone. The joints are well-welded when the welding speed is 300~800 mm/min, and the fracture occurring in the HAZ of the retreating side could be mainly attributed to the temperature（400~480 ℃），dissolution of the precipitation phase leads to a significant reduction in the mechanical properties，and in this welding speed range，the joint strength increases with the increase of welding speed，and the highest strength factor is 80.86%（800 mm/min）. As the welding speed is further increased to 1 200 mm/min, the weld formability of the joint would deteriorate significantly due to the insufficient heat input and thermo-plasticity. Besides, the un-welded and tunnel defects in the weld nugget lead to the occurrence of the fracture in the nugget zone during tensile test.

Abstract:In this paper, the microstructure characteristics, fatigue properties and fracture mechanism of 95 mm Al-Cu-Li alloy hot-rolled thick plates in different orientations were studied by fatigue testing machine, scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the mechanical properties and fatigue properties of Al-Cu-Li alloy hot-rolled thick plate were both anisotropic. The mechanical properties of the L direction are better than those of the ST direction, but the fatigue properties are worse than those of the ST-direction. The fatigue crack sources of Al-Cu-Li alloy thick plates mainly appear on the surface of the sample, near the surface of the inclusions and grain boundaries. During the crack propagation process, the crack propagation path in the LT direction was more tortuous than that in the L direction, and the ST direction had a typical cleavage characteristic. The morphology of the instantaneous fracture zone was similar to that of the tensile fracture. The more grain boundaries, the greater the crack propagation resistance, and the undissolved second phase in the LT direction and ST direction can effectively hinder the crack propagation, resulting in better fatigue performance than that in the L direction.

Abstract:In order to improve the power factor of Magnetic-Geared Flat Linear Machine (MGFLM), this paper derives the analytical formulas of its air gap flux density and power factor, and investigates the influence of the variables on the basic physical quantities of the motor. The main variables affecting the power factor are determined as the permanent magnet distribution, the width of the tooth shoe and the shape and dimensions of the magnetizer block. Secondly, based on the parameterized finite element simulation of the MGFLM in Ansys Maxwell, a polynomial response surface model for the average thrust and power factor of the motor is established. Finally, Box-Behnken method was applied to optimize the motor. The power factor of the optimized MGFLM is increased by 44.9% from 0.497 to 0.720.

Abstract:A high-performance Narrow Band Internet of Things (NB-IoT) wireless street lamp controller is designed in this article. The wireless communication module of this street lamp controller is achieved by using the NB-IoT transmission module M5311, and the embedded single-chip STM8 is taken as the controller. Electrical parameters such as voltage, current, power, electrical energy, and power factor of street lamps can be measured in real time by the intelligent electrical energy collection chip HLW8112 in the designed street lamp controller, which has the functions of lamp fault diagnosis and alarm, remote or local gradation and instant dimming of lamps, power switch control and so on. The interface circuit between M5311 and CPU, D/A dimming circuit and electrical parameters acquisition circuit of wireless street lamp controller, the main program, timer interrupt service subroutine, networking service subroutine, instruction analysis subroutine, fault diagnosis subroutine of the control program and communication protocol between street lamp controller and remote control platform are analyzed and designed. The experimental results of the street lamp controller test platform verify the functions and performance of the NB-IoT wireless street lamp controller, which can meet the requirements of modern urban street lamp intelligent control.

Abstract:In order to reduce fuel costs and achieve scientific fuel control in coal-fired power generation enterprises, a bi-level fuel cost optimization model that comprehensively considers the reliability of power generation and the economy of production is proposed in this paper. The upper layer is a mixed integer programming model for power coal purchasing and inventory, while the lower layer is a nonlinear optimization model for mixed coal combustion. The bi-level model is the alternating iterative coordination optimization to realize the dynamic decision-making of fuel control. Then, an improved gray wolf optimization algorithm combining chaos mapping initialization and Gaussian mutation is proposed for the high dimensional and multiple constraints of the optimization model. Finally, a simulated operation of a coal-fired power plant is used to verify the results. The results show that the proposed model can reduce the coal cost of coal fired power plant by 7.80%, which proves the effectiveness and feasibility of the proposed model and solution algorithm.

Abstract:To identify the interacting proteins of transactivation domain of forkhead box protein M1 which is located on the 688th to the 748th amino acid sequence of C-terminal end，the cDNA of FOXM1 was used as a template, the transcription activation domain sequence was amplified by polymerase chain reaction and cloned into the prokaryotic expression vector pGEX-4T2. The recombinant protein GST-FOXM1688-748 fused with glutathione S- transferase tag was obtained by Escherichia coli prokaryotic expression. The interacting proteins were identified by GST-pulldown assay and mass spectrometry. The pGEX-4T2-FOXM1688-748 prokaryotic expression plasmid was constructed successfully and the FOXM1688-748 recombination protein was obtained. According to the mass spectrometry results, the interacting proteins were analyzed and classified to show that some of them activated the transcriptional activity of FOXM1, such as RPN2, MISP, and MCM7 proteins, and some of them regulated the stability of FOXM1 protein, such as USP9Y, CUL4A, HSPB1, and BAG2 proteins. The transcription activation domain of FOXM1 protein interacts with many proteins participating in different pathways, indicating that this domain has an important molecular biological role, which can expect to provide experimental basis for clinical drug development targeting FOXM1.

Abstract:In order to explore whether Hepatitis B virus (HBV) can escape the body’s immunity by means of the anti-immune mechanism of tumor cells, this study used HBV to infect hepatocytes, and then explored the changes of the immune response of infected hepatocytes to the host. The transcriptional levels of Axin and PD-L1 in hepatocytes after HBV infection were analyzed by real-time fluorescence quantitative PCR, and it was found that HBV did not affect the transcriptional levels of Axin and PD-L1. Then, western blot was used to find that HBV could down-regulate Axin protein levels in hepatocytes and up-regulate PD-L1 protein levels. Further transfection of plasmid expressing HBV component protein in cells showed that HBx could down-regulate Axin protein expression in cells by western blot. Data correlation analysis and ubiquitin assay showed that Axin promoted pD-L1 ubiquitin proteasome degradation by increasing the expression of E3 ubiquitin ligase SPOP of PD-L1. Further studies on the ubiquitination of PD-L1 showed that Axin promoted the K48-dependent ubiquitination of PD-L1. Based on the above results, we believe that HBV may down-regulate Axin and SPOP protein levels through HBx, inhibit PD-L1 ubiquitination and degradation, and then escape the host immune response. This study reveals a new mechanism of HBV immune escape, lays a new foundation for the treatment of HBV, and promotes the development of anti-HBV drugs to a certain extent.

Abstract:To solve the air pollution in the process of slagging in the high-altitude construction tunnel and improve the effect of ventilation, a high-altitude tunnel gas diffusion model was constructed based on the changes in environmental parameters at altitude and the theory of turbulence diffusion. Taking a tunnel of Sichuan-Tibet Railway at an altitude of 3 200 m as the research background, the environmental parameters and carbon monoxide （CO）concentration in the tunnel were measured. A construction tunnel slagging model was established by SolidWorks and ANSYS softwares. The component transport equation in Fluent was used to dynamically simulate the law of harmful gas migration and mass concentration distribution at different altitudes. The results show that when the internal combustion engine is operated in the tunnel, the CO distribution is uneven and the range is large near the tunnel working face head-on. Near the exit of the tunnel, the CO distribution gradually stabilized. The CO mass fraction in the tunnel increases with the increase of altitude, but the CO mass concentration shows an opposite trend. From 0 m to 6 000 m, the CO mass fraction increased by 96%, but the influence of environmental parameter changes on the CO mass concentration is more important than the CO emissions, resulting in a decrease of 18% in the CO mass concentration. As a result, the air demand increases non-linearly with altitude while keeping the CO mass fraction constant in the tunnel. According to the obtained air demand calculation model, when the altitude is 3 200 m, the air demand is about 4.95 m3/（kW·min）.