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Journal of Chongqing University of Technology(Natural Science)

Table of Content

    21 June 2023, Volume 37 Issue 5 Previous Issue    Next Issue
    Vehicle engineering

    Optimization of transmission ratio of dual-motor hybrid power coupling devices based on the exhaustive method

    2023, 37 (5):  1-11. 
    Abstract ( 544 )   PDF (3768KB) ( 455 )   Save

    A large number of researches have been carried out in China on speed ratio optimization of the transmission system, such as genetic algorithm, particle swarm optimization algorithm and PARETO optimal solution. The principle of gear ratio optimization is to evaluate the power and economy of the system under different gear ratio combinations, and then select the gear ratio combination with the best performance. When the gear ratio combination changes, the system shift pattern will change, and it is necessary to recalculate the shift pattern for each gear ratio combination, which adds complexity to the entire optimization calculation. The existing gear ratio optimization methods do not consider the changes in gear shifting patterns under different gear ratio combinations, or simplify them to varying degrees, which to some extent affects the calculation accuracy. This poses challenges to the implementation of various optimization algorithms.

    Therefore, targeted solutions are proposed to address the issue. Firstly, a speed ratio optimization method for power coupling devices based on the exhaustive method is proposed to address the situation where the gear ratio optimization is prone to falling into local optima and the shifting patterns may change under different gear ratio combinations. Then, the results obtained through this algorithm cover all gear ratio combinations and can intuitively reflect the changes in fuel consumption and power performance under different gear ratio combinations. This method can ensure the globally optimal calculation results, and can quickly select the required speed ratio combination based on the calculation results when the economic and dynamic requirements change. Besides, in response to the problem of high computational complexity in the exhaustive method, biased proportional constraints, impact constraints and dynamic constraints are added to the speed ratio combination based on the previous speed ratio optimization, reducing the search range of speed ratios. In the calculation of gear shifting patterns under different gear ratios, multi threaded technology is used to optimize the calculation, keeping the calculation time within a reasonable range.

    The final result shows that at low speeds, with medium to low valve openings, the optimized speed ratio of the operating point of the car engine increases, and the economy is effectively improved. In addition, the results before and after the optimization are obtained through simulation of the economic and power shift patterns. Through data analysis, it can be seen that although the power performance of the optimized vehicle decreases by 11.15%, the economic efficiency increases by 4.44%, which fails to validate the rationality of this method.

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    Research on rapid integration of drive control strategies for pure electric vehicles

    2023, 37 (5):  12-18. 
    Abstract ( 377 )   PDF (3005KB) ( 424 )   Save
    In order to solve the problem that application layer codes and underlying driver codes need to be manually integrated in the development process of the automotive electronic control system, this paper uses Matlab/Simulink to design application layer control strategies for pure electric vehicle controllers as the research objects, including vehicle power-on and power-off, key signal analysis, gear management, torque analysis and torque arbitration. The underlying driver is firstly configured by STM32-MAT/Target toolkit and STM32Cubemx, and then the configured underlying driver can be dragged into the Simulink interface as a graphical module so as to be built on the same platform as the application layer control strategies do. Finally, all the embedded C codes are generated with one key by using Simulink automatic code generation, and the STM32F407ZGTE micro-controller is used as the hardware platform to select several typical driving conditions for real-time algorithm verification. The results show that the generated codes work well in the target system and can run according to the designed logic. Compared with manual integration, this fully automated development method reduces manual input errors, improves development efficiency and speeds up the entire process from design to implementation.
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    Research on integrated control of four-wheel steering and yaw moment for distributed drive electric vehicles

    2023, 37 (5):  19-28. 
    Abstract ( 204 )   PDF (4724KB) ( 255 )   Save
    Aiming at the stability control of distributed drive electric vehicles with four-wheel independent drive and independent steering, this paper proposes an integrated control strategy of four-wheel steering and yaw moment. Based on the fuzzy theory, it designs the upper controller by adopting the hierarchical control structure. Then, it calculates the additional rear wheel angle and the additional yaw moment according to the expected yaw velocity and the deviation between the desired yaw angle of the center of mass and the actual value. The lower controller includes a four-wheel angle controller a four-wheel moment distributor. The additional rear wheel angle controller adopts proportional feedforward plus fuzzy feedback or Ackerman steering respectively to control the additional rear wheel angle according to the steering wheel angle and the vehicle speed. In accordance with the additional yaw moment demand, the four-wheel moment distributor uses quadratic programming algorithm to optimize the four-wheel moment allocation. By selecting typical experimental conditions, this paper verifies the integrated control strategy of rear-wheel steering and yaw moment through co-simulation experiments. The results show that the integrated control strategy can effectively improve the stability of distributed drive electric vehicles.
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    Predictive current control of permanent magnet synchronous motors based on adaptive forgetting factors

    2023, 37 (5):  29-36. 
    Abstract ( 125 )   PDF (2326KB) ( 116 )   Save
    Since model predictive control (MPC) works based on a motor model, the mismatch between the actual parameters of the motor and the parameters of the predicted model will lead to a decrease in the control performance of the system. Aiming at this problem, this paper proposes a least square parameter identification method by using adaptive forgetting factors. This method adjusts the forgetting degree of the old data in the identification process through the changing forgetting factors so that the identification results have fast convergence and can stably follow the changes of the motor parameters. The parameters of the prediction model are corrected in real time by identifying the motor parameters, which can effectively reduce the current and torque fluctuations caused by changes in motor parameters. The control performance and the parameter robustness of the MPC algorithm are both improved. Finally, Matlab/Simulink is used for simulation analysis, and its results verify the effectiveness of the method.
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    Research on optimization of the energy management strategy of a series-parallel hybrid electric vehicle

    2023, 37 (5):  37-43. 
    Abstract ( 155 )   PDF (1829KB) ( 326 )   Save
    This paper firstly proposes a rule-based logic threshold energy management strategy developed by manual calibration for a series-parallel hybrid electric vehicle. On the basis of the calibrated logic threshold, the dynamic programming algorithm is then introduced to optimize the vehicle optimal control, and the proposed logic threshold strategy is further optimized according to the optimal strategy data set. Finally, a real vehicle experiment is carried out on a hybrid electric vehicle equipped with an energy management strategy based on optimized logic threshold rules. The experimental results show that the optimized energy management strategy has a good fuel saving effect, and an improvement of 4.7% in fuel saving can be reached, which effectively improves fuel economy and meets the real-time requirements of the vehicle control, providing technical support for the subsequent product development of hybrid electric vehicles.
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    Optimized control of heat dissipation performance by linear quadratic regulators of lithium battery packs

    2023, 37 (5):  44-53. 
    Abstract ( 116 )   PDF (4840KB) ( 80 )   Save
    In order to maintain the operating temperature of lithium ion battery packs in a reasonable and safe operating range, this paper proposes a linear quadratic regulator to control the maximum battery temperature, temperature difference and energy consumption of the liquid-cooling battery thermal management system. By inputting the current into a battery under the operation condition of NEDC and US06, heat generation models are built by using Matlab-Simulink and Amesim software. The battery temperature and temperature difference curves are obtained and the reliability of the models are validated. Under 3C charging and -NEDC discharging conditions, a comparative study of the thermal management capacity is carried out among LQR, PID and constant flow rate control. The results show that the battery thermal management system based on LQR control has a good response speed and stability. By comparing the effect of the three controllers on the maximum temperature difference of BTMS, it is found that the LQR controller exhibits the best control capacity when the liquid-cooling channels of the battery pack are arranged in reverse. Compared with PID and the constant current controller, the LQR controller can reduce cooling energy consumption.
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    Research on optimization of temperature and humidity control of proton exchange membrane fuel cells for vehicles using LADRC

    2023, 37 (5):  54-59. 
    Abstract ( 151 )   PDF (2189KB) ( 198 )   Save
    In view of the instability of the hydrothermal management system of proton exchange membrane fuel cells when the power changes and the large temperature difference between the coolant at the inlet and the outlet of the stack, this paper establishes a hydrothermal management system model of proton exchange membrane fuel cells considering influencing factors like power change of the vehicle and the driver’s demand through the LMS AMESim simulation platform. Matlab-Simulink is also used to build a linear active disturbance rejection controller (LADRC) algorithm and a proportional integral derivative (PID) control algorithm to control the cooling water pump and the humidity regulator so as to stabilize the temperature and humidity of the stack. Besides, joint simulation analysis is carried out to compare the control effects of the two under the new European driving cycle (NEDC) working condition. The results show that the hydrothermal management system can keep the temperature and humidity of the fuel cell stack within an appropriate operating range under NEDC conditions, and the LADRC performance is better than PID. The maximum temperature difference between the coolant at the inlet and the outlet of the stack is about 5 ℃, and the output voltage of the stack increases by 2.08% on average. It can provide certain basis and guidance for the research and test of the hydrothermal management of proton exchange membrane fuel cells.
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    Research progress of cooling technology for vehicle lithium ion batteries

    2023, 37 (5):  60-69. 
    Abstract ( 365 )   PDF (1751KB) ( 551 )   Save
    Promoting new energy vehicles is one of the effective ways to accomplish China’s “carbon peak” and “carbon neutrality” goals and to deal with the global climate crisis. Compared with other types of batteries, such as nickel-metal hydride batteries and lead-acid batteries, lithium ion batteries have the advantages of a high energy density, high efficiency, long life and environmental friendliness, and have been widely used. Therefore, new energy vehicles with lithium ion batteries as the energy system have also evolved rapidly. However, a proper operating environment is the key to ensuring efficient operation of lithium ion batteries. If the environmental temperature is too high, a lithium ion battery may suffer from thermal runaway, which may lead to burning or explosion. If the environmental temperature is too low, charging and discharging performance of a lithium ion battery will be affected, and the surface of the negative electrode is prone to disaggregating lithium and producing dendrites, resulting in capacity decay and even piercing the separator to form an internal short circuit. Therefore, developing an effective thermal management system to make lithium ion batteries operate within a suitable temperature range is the key to ensuring safe and stable operation of new energy vehicles. This article systematically analyzes the existing cooling technologies of lithium ion battery thermal management system and compares their advantages and disadvantages. Lastly, the future development trend of the electric vehicle thermal management system is discussed based on the current development state of the lithium ion battery thermal management system.
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    Vibration and noise optimization of drive motors considering harmonic currents

    2023, 37 (5):  70-80. 
    Abstract ( 110 )   PDF (4704KB) ( 212 )   Save
    Aiming at the driving motor NVH problems caused by radial electromagnetic force of low orders, this paper gathers noise signals of a driving motor to analyze their order characteristics. An electromagnetic-structure-acoustic simulation model is also built and its accuracy is verified through experimental signals. An analytical model of radial electromagnetic force considering harmonic currents is established based on Maxwell tensor method. Besides, the radial electromagnetic force waves of the main time orders of are decomposed both on time and space dimensions. Combined with the transfer functions from each stator tooth of the motor to the noise measurement point, a noise prediction model at the measurement point is established based on the linear superposition method. The concentrated force of the radial electromagnetic force waves on each stator tooth is calculated by Cotes formula. By applying the formula to the noise prediction model, the contribution degree of various time and spatial orders of the radial electromagnetic force to the noise at the measuring point is obtained. Therefore, the harmonic current order that greatly affects the noise is figured out. Taking the noise pressure level at the measuring point as the optimization objective, the amplitude and phase of the harmonic currents are optimized through the genetic algorithm by considering the influence of the harmonic currents on torque pulses as the restriction condition. The optimized harmonic currents are injected into the electromagnetic-structure-acoustic simulation model to verify the optimization effect. The results indicate that, through the optimization of the harmonic currents, the motor vibration noise can be decreased by optimizing the radial electromagnetic force under the premise of controlling the torque pulse.
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    Simulation optimization of the air conditioning and heating system of a certain pure electric vehicle

    2023, 37 (5):  81-89. 
    Abstract ( 107 )   PDF (2443KB) ( 155 )   Save
    In order to improve the problem of energy consumption in the low temperature heating system of a pure electric vehicle, through the simulation software AMEsim, this paper builds a hydraulic thermal management model based on the low temperature thermal management structure scheme of a pure electric vehicle heated by PTC heating, and verifies the reliability of the simulation results by the test data. The control strategy of the low temperature heating system is optimized, and a motor waste heat utilization model is added to the structure. The effects of ambient temperature, strategy scheme and driving conditions on the heating performance and energy consumption of the system are further analyzed through simulation. The simulation results show that the energy consumption of the optimized model reduces by 26.2% under two NEDC conditions, which increases the economy of the system.
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    Thermal fatigue life prediction of cast aluminum alloy casing of vehicle permanent magnet synchronous motors

    2023, 37 (5):  90-98. 
    Abstract ( 112 )   PDF (3804KB) ( 106 )   Save
    In order to study the effect of temperature variation on thermal stress and thermal fatigue life of cast aluminum alloy casing of a vehicle permanent magnet synchronous motor under variable working conditions, this paper combines theories, experiments and finite element simulation to conduct a multi-physical field coupling study on the casing. Firstly, the ambient temperature of the motor as the boundary condition for simulation calculation, and the winding end temperature as the reference of the simulation results are collected experimentally. Then, the main losses of the motor are calculated, and the temperature field distribution of the motor casing is obtained through simplified modeling and finite element simulation of the motor based on heat transfer and fluid dynamics. Afterwards, basic material parameters of the thermal fatigue life prediction model of the cast aluminum alloy are obtained through the experiment. The thermal stresses of the casing under different temperature distributions are also calculated by combining the temperature field results. Finally, the thermal fatigue life of the casing under the thermal stresses is obtained as 29 673 times. This study provides a certain reference basis for the design optimization of the motor casing and the selection of materials.
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    Research on adhesion stability control of distributed drive electric vehicles

    2023, 37 (5):  99-109. 
    Abstract ( 120 )   PDF (4871KB) ( 447 )   Save
    By analyzing the influence mechanism of vertical load transfer of wheels on tire adhesion margin, this paper develops a direct yaw moment control strategy to give full play to the vehicle ultimate adhesion driving ability. A hierarchical control structure is adopted. The upper layer is the decision-making layer of the additional yaw moment. The model predictive control algorithm is used to solve the required additional yaw moment. The lower layer is the optimal distribution layer of the four-wheel torque, and the additional yaw moment obtained from the upper layer is optimally distributed to each wheel to correct the body attitude. Through the joint simulation test of Matlab/Simulink and CarSim and a hardware-in-the-loop experiment based on a dSPACE LabBox driving simulator bench, the rationality of the torque distribution mode and the effectiveness of the control strategy are verified. The experimental results show that the strategy effectively improves adhesion of each wheel, and improves the vehicle ultimate driving ability and adhesion stability.
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    Machinery and materials

    Research on the air-cooling heat dissipation flow field of the battery system of a special energy storage shelter

    2023, 37 (5):  110-117. 
    Abstract ( 157 )   PDF (3867KB) ( 176 )   Save
    Due to the requirements of infrared stealth performance, the heat dissipation structure layout of a special energy storage shelter is limited. This research takes the battery system of a special energy storage shelter as the research object, and studies and analyzes heat dissipation caused by high rate discharge in a high temperature environment. A heat generation model of a battery module is constructed by using a heat generation model of size 18650 single lithium ion batteries, and simulation and tests of the temperature rise of the battery module are carried out to verify the accuracy of the heat generation model of the battery module. On this basis, the research numerically simulates forced air-cooling heat dissipation of the air conditioning of the special energy storage shelter, and calculates the temperature and the pressure at the discharging end node under specific extreme conditions. Besides, it obtains the temperature field and the pressure field inside the special energy storage shelter to explore the heat dissipation effect of its stealth air-cooling heat dissipation structure. The results show that in a high temperature environment of 40 ℃, the special energy storage shelter discharges at 3 C, and its air-conditioning forced air cooling system can still effectively ensure that the battery temperature remains within a reasonable working range.
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    Vehicle engineering

    Bamboo-like structure design and multi-objective optimization of guiding arms of a composite air suspension

    2023, 37 (5):  118-128. 
    Abstract ( 93 )   PDF (4167KB) ( 154 )   Save
    In view of the lightweight of a composite air suspension guiding arm, inspired by the structural characteristics of cross-section shape, variable sections and joints of bamboos, this paper designs a bionic guiding arm through the structural bionic method. Through parameter sensitivity analysis, key parameters affecting the performance of the bionic guiding arm are firstly investigated. With a great influence on the performance of the guiding arm, the rib plate and inner hole cross-section parameters are then selected as the design variables. Besides, the total mass and the minimum value of maximum deformation of the guiding arm are selected as the optimized targets for multi-objective optimization. Finally, the optimal parameter scheme of the Pareto solution set is determined by combining entropy-weight TOPSIS-gray correlation analysis with the multi-objective decision method. The results show that, under the premise that the mass of the prototype guiding arm reduces by 17.44%, the bionic guiding arm after multi-objective optimization shows a decrease in the maximum deformation by 9.24%, a decrease in the equivalent force by 17.33%, and an increase in the first-order prestressed constraint mode frequency by 22.92%. The study in this paper strongly proves the feasibility of the structural bionic design optimization method in the lightweight design of the guiding arm, which has certain reference significance for the structural lightweight design of guiding arms.
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    Machinery and materials

    Stochastic prediction of the remaining fatigue life based on continuum damage mechanics

    2023, 37 (5):  129-134. 
    Abstract ( 110 )   PDF (1822KB) ( 233 )   Save
    Due to the randomness of material properties and external loading, the predicted remaining fatigue life under variable amplitude loading often has a very great dispersion. Thereby, to quantify the uncertainty of the remaining fatigue life arising from material properties and external loading, this paper proposes a remaining fatigue life prediction method under two-level loading. This proposed method mainly consists of four steps. Firstly, considering the randomness of external loading, a nonlinear damage accumulation model based on continuum damage mechanics is applied. Secondly, considering the randomness of material properties, three-parameter S-N curve under different reliability is adopted. Thirdly, in order to screen the model parameters that contribute greatly to the randomness of the predicted remaining fatigue life, a global sensitivity analysis based on Sobol method is introduced. Finally, the K-L divergence method is utilized to quantify the differences between the predicted and the probability distribution of the experimental remaining fatigue life. In addition, the effectiveness of the proposed method is verified through the fatigue test data of hot-rolled 16 Mn alloy steel.
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    First principle study on the properties of cubic BaTiO3 doped with elements (M=Fe, Mn)

    2023, 37 (5):  135-141. 
    Abstract ( 105 )   PDF (4420KB) ( 150 )   Save
    The crystal structure, electronic structure, magnetic moment and dielectric function of an element (M=Fe, Mn) doped with cubic BaTiO3 (in which the chemical formulas are BaFexTi1-xO3 or BaMnxTi1-xO3, and x is 0, 1/8, 1/4, 3/8 or 1/2) are calculated by using the first principle method under the framework of the density functional theory. The results show that, when x is 1/8, the crystal structure of BaTiO3 remains cubic phase, while, when x is greater than 1/8, the crystal structure of BaTiO3 changes into tetragonal ferroelectric phase. The addition of Fe or Mn makes BaTiO3 obtain great magnetism, and the total magnetic moment mainly comes from the contribution of the local magnetic moment of Fe or Mn ions. With the increase of element doping, the magnetism of BaTiO3 increases. At the same time, by comparing the static dielectric constant before and after doping, it is found that the doping of element Fe or Mn makes the static dielectric constant of BaTiO3 change greatly, which is much larger than that of the undoped BaTiO3. Therefore, Fe and Mn are easier to obtain the high dielectric constant.
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    Simulation research on thermal runaway of lithium ion batteries induced by high temperature

    2023, 37 (5):  142-149. 
    Abstract ( 141 )   PDF (3352KB) ( 153 )   Save
    In order to improve the safety of lithium ion batteries and reduce safety accidents caused by thermal runaway of lithium ion batteries, this paper uses a commercial 18650 ternary lithium ion battery as the research object, and establishes a three-dimensional thermal runaway model induced by high temperature through COMSOL Multiphysics 5.6. By comparing temperature rise curves under different induced temperatures and different heat transfer conditions, the influence of induction temperature and heat transfer coefficient on the thermal runaway of lithium ion batteries is analyzed and explored. The results show that under different temperatures, the higher the induced temperature is, the higher the thermal runaway temperature peak is and the earlier the thermal runaway occurs. Under different heat transfer conditions, the larger the convective heat transfer coefficient is, the earlier the thermal runaway occurs and the larger the temperature drop gradient is after reaching the peak. Besides, the participation of cathode materials in the reaction can be regarded as a key characteristic of thermal runaway.
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    Information and computer science

    Research on choice behaviors of arriving at an airport considering the heterogeneity of travelers

    2023, 37 (5):  150-158. 
    Abstract ( 97 )   PDF (1463KB) ( 87 )   Save

    In order to analyze the preference and influencing factors of air passengers’ travel mode choice of getting to an airport, this paper establishes a latent category Logit model considering the heterogeneity of passengers’ psychological fatigue. Firstly, a questionnaire survey at Nanjing Lukou Airport is conducted to obtain individual characteristics, psychological states and travel habits of 580 travelers, and psychological states of travelers are quantified by a five-level Likert scale, in which intrinsic attributes of the psychological states include perceived risk, emotional reflection, attitude reflection and perceived convenience. Secondly, the psychological state of travelers is assessed by using the psychological state scale, which includes seven dimensions: tension, fatigue, panic, depression, anger, energy and sense of self-esteem. Travelers are also classified according to the psychological fatigue score, and a latent category Logit model is established and compared with the mixed Logit model for analysis. Finally, the model parameters and marginal effects are evaluated, and the factors influencing air travelers’ choice of airport arrival modes are analyzed based on the model results.

    The results show that the prediction accuracy of the latent category Logit model is 60.8%, and that of the mixed Logit model is 55.9%, indicating that the latent category Logit model has a better fitting effect. According to the classification of passengers’ mental fatigue, passengers can be classified into low, medium and severe mental fatigue types, accounting for 36%, 48% and 16% respectively. The low, medium and severe mental fatigue travelers correspond to the subway preference group, the airport bus preference group and the cab preference group respectively. Travelers’ gender, age, income, body mass index and situations like whether they carry bulky luggage, whether they own a private car, and whether they travel alone also have significant effects on the choice of arrival mode.

    An increase in mental fatigue makes travelers less sensitive to travel costs, and travelers with low mental fatigue are more concerned about travel costs and tend to choose the subway or an airport bus as the mode of arrival to the airport. Therefore, city public transport providers can provide targeted services to improve traveler satisfaction by identifying the characteristics of air travelers. In the group of travelers with low psychological fatigue, perceived risk and emotional response are significant, and their coefficients are negative: for an increase of each unit, the probability ratio of travelers belonging to the subway preference group decreases by 48% and 42% respectively. However, attitude reflection and perceived convenience are significant, and their coefficients are positive: for an increase of each unit, the probability ratio of travelers belonging to the subway preference group increases by 89% and 67% respectively. In addition, in the group of moderately mentally fatigued travelers, the coefficients of perceived risk and emotional response are significant and negative, with an increase of each unit decreasing the probability ratio of travelers belonging to the airport bus preference group by 49% and 46% respectively. Consideration of psychological characteristics in the choice of travel mode has important implications for a deeper understanding of sustainable transportation.

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    A nonlinear impact model of community built environment on vehicle miles traveled of middle-income groups

    2023, 37 (5):  159-168. 
    Abstract ( 93 )   PDF (2824KB) ( 84 )   Save

    With an increasing proportion of middle-income groups in the population structure, quantitative analysis of the nonlinear impact of community built environment on vehicle miles traveled (VMT) of middle-income groups has become an important basis for finely guiding the community life circle to create a green travel built environment. Based on the 5D of the built environment, this paper selects six indicators such as population density, land use diversity and public transport service levels to describe the built environment of a community.

    Based on the 15-minute community life circle and walking speed in Technical Guide for Community Life Circle Planning, the measurement range of the community life circle is formed. The built environment is measured by combining point of interest (POI) data, road networks and other geospatial data. Taking Baoding residents’ travel behavior survey data as the source of empirical research, this paper constructs a gradient boosting decision tree (GBDT) model that considers nonlinear effects. In terms of model fitting, the GBDT model improves the adjusted R2 76% higher than the ordinary least squares (OLS) model with linear assumptions does, and performs better than machine learning models such as Support Vector Machine (SVM) and Random Forest (RF) do, indicating that the GBDT model has better adaptability in this study. In terms of the contribution of built environment indicators, the built environment attributes have a greater effect on VMT than individual social and economic attributes do, with land use mixing degree (19.10%) and distance from the city center (17.23%) contributing the most to VMT of middle-income people, which reflects the important role of reasonable land use planning in regulating middle-income people’s car use. In addition, the lowest contributor is public transportation service level (5.72%). This may be due to the fact that the middle-income group has a high travel demand with high time efficiency and high quality requirements for travel modes, and based on the preliminary research, the existing public transportation service level in the study area is still low, resulting in an inability to effectively attract the middle-income group. In terms of the nonlinear relationships of built environment indicators, the built environment factors have nonlinear relationships with VMT. The overall relationship between population density and VMT is “V-shaped”, and the lowest value of the VMT curve corresponds to a population density of 18 000 people/km2. The overall effect of community land use mixing on VMT is negative, and the threshold effect point is 0.6. When the land use mixing exceeds 0.6, it can effectively limit VMT. The influence of road density and intersection density on VMT is negatively correlated, and their threshold points are 7.6 km/km2 and 22 /buffer respectively. Overall, the impact of public transportation service levels on VMT is positively correlated, with no significant threshold relationship. For the bivariate interaction non-linear relationship, the influence of land use mixing, bus stop density and distance from the city center on VMT has a certain interaction effect with the driving age.

    In general, the effect of the built environment on VMT reduces as the driving age increases. In particular, the inhibitory effect of land use mixing on VMT is substantially weak for those who have been driving for more than 10 years. In terms of public transportation service levels, for those with more than 3 years’ of driving experience, the effect on controlling the intensity of car use among middle-income people is less pronounced. In terms of distance from the city center, for those with more than 7 years’ of driving experience, the effect of reducing the distance from the city center on suppressing small car use begins to diminish. Among the nonlinear effects of the built environment on VMT, it is worthwhile for planning managers to pay attention to the inflection point of nonlinearity, which contains the optimal value range of built environment indicators on the one hand and the effect range of built environment indicators on the other hand. Therefore, community spatial planners are advised to develop a refined design of community built environment in order to effectively suppress VMT.

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    Short-term traffic flow prediction based on variational modal decomposition and LSTM

    2023, 37 (5):  169-177. 
    Abstract ( 152 )   PDF (4078KB) ( 143 )   Save
    Traffic flow has the characteristics of nonlinearity, volatility and randomness. In order to further improve the prediction accuracy of short-term traffic flow, this paper proposes a short-term traffic flow prediction method based on variational modal decomposition (VMD) and long and short-term memory (LSTM) neural network. Firstly, VMD is used to decompose the original traffic flow data into k stable Intrinsic Mode Functions (IMF). Then, LSTM models are input into each modal component for prediction, and all of the predicted values are summarized and superimposed to obtain the final traffic flow prediction results. Based on the induction coil data of Shanghai North-South Elevated Expressway, the results show that the prediction result after VMD decomposition is more accurate. Compared with the prediction results of BPNN, LSTM, EMD-LSTM and EEMD-LSTM, the mean absolute error (MAE) is optimized by 35.5%, 28.25%, 21.1% and 13% respectively, showing a high prediction accuracy.
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    Sentiment analysis of short Chinese texts integrating capsule networks

    2023, 37 (5):  178-184. 
    Abstract ( 109 )   PDF (1308KB) ( 100 )   Save
    In order to address the shortcomings of traditional text classification models in incomplete extracting the intrinsic semantic information of short Chinese texts, this paper proposes a text classification model that fuses pre-training models and capsule networks. A multi-scale convolutional neural network is firstly used to extract the local semantics in each layer of different levels of the pre-training model. After that, an attention mechanism is used to fuse the obtained multi-grained local semantics and the global semantics obtained through the capsule network, which is then combined with a regularization method to improve the discrimination ability of the model to the sentiment polarity of the text. Finally, the F1 values of the model in the experiment are compared with the real datasets in three different domains. The experimental results show that the model can extract the semantic features of the short Chinese texts more comprehensively by using the improved capsule network, which improves the accuracy of sentiment polarity discrimination.
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    Stroke lesion segmentation based on convolution fusion and residual-attention mechanism

    2023, 37 (5):  185-193. 
    Abstract ( 132 )   PDF (3331KB) ( 150 )   Save
    Stroke MRI images are difficult to be segmented due to small lesion areas and blurred boundaries between lesions and healthy tissues. Therefore, this paper proposes an optimized encoder-decoder structure network. Firstly, in order to extract richer contextual information for the network, a dual-attention convolution fusion coding module is established, which combines 2D convolution with 3D convolution on the contraction path of the encoding end, and builds global correlation of the features from both space and channel dimensions. In addition, a residual-attention gate hybrid decoding module is proposed to better fuse low-level and high-level features and focus on the target area, thereby improving the segmentation fineness of the edges of the small lesions. The experimental results in the open source dataset anatomical tracings of lesions after stroke (ATLAS) show that the DSC index of the algorithm reaches 0.62. Compared with models such as UNet, D-UNet, 3D-UNet and attention-UNet, it demonstrates a much improved segmentation performance.
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    Certificate-free distributed anonymous authentication scheme based on UTXO in vehicular ad-hoc network

    2023, 37 (5):  194-203. 
    Abstract ( 137 )   PDF (3114KB) ( 117 )   Save
    Aiming at the issues of low authentication efficiency and poor scalability in traditional ID authentication schemes based on digital certificates, this paper proposes a certificate-free distributed anonymous authentication scheme based on the unspent transaction output (UTXO) model. Users upload traffic messages to the Regional Trusted Authority (RTA) together with transactions generated based on the UTXO model. The RTA verifies the legitimacy of the message sender’s identity by checking the validity of the transaction input contained in the uploaded transaction. In addition, this paper designs a transaction update mechanism to guarantee the scheme scalability, avoiding a continuous increase in the system database storage caused by maintaining digital certificates. Based on the security analysis, compared with the existing identity authentication schemes in vehicular ad-hoc network (VANET), the proposed scheme is better in terms of security considerations such as anonymity, traceability and authentication. The theoretical analysis and the simulation experiments show that computational and storage costs of the proposed scheme are lower than those of the existing common authentication schemes. In terms of scheme scalability, the retrieval overhead of the blockchain state database based on the simulation environment remains at around 0.3 ms, while the storage cost is stable at around 33 M. In terms of authentication efficiency, the proposed scheme outperforms the existing schemes by at least 33.19%.
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    Dynamic analysis of the SEILR rumor spreading model with recurrence

    2023, 37 (5):  204-209. 
    Abstract ( 109 )   PDF (1578KB) ( 139 )   Save
    Based on the rumor spreading mechanism, considering the rumor recurrence caused by the interpersonal factor, this paper establishes a SEILR rumor spreading model, and studies the impact of this factor on rumor spreading. Firstly, the rumor spreading threshold R0 is given, and the stability of the rumor-free equilibrium point is analyzed when R0<1. Secondly, the existence of multiple equilibrium states is analyzed, and the condition of the occurrence of backward bifurcation is given. Then, the global asymptotic stability of the positive equilibrium point of the degenerate model is proved by constructing Lyapunov function. Finally, through numerical simulation, it is found that degenerate Hopf bifurcation appears and there are two limit cycles in the model, in which the large one is unstable and the small one is stable. The results show that the rumor recurrence caused by interpersonal factors can change the dynamic spreading trend of the rumors.
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    A fast apple recognition algorithm based on improved neural networks

    2023, 37 (5):  210-217. 
    Abstract ( 160 )   PDF (4527KB) ( 133 )   Save

    Aiming at the problems of insufficient computing power, limited target detection speed and difficulty in meeting real-time application of edge equipment of a picking robot, this paper proposes a lightweight algorithm based on improved YOLOv4, which improves detection speed and reduces network volume, and can be better applied to edge equipment. In this paper, the lightweight backbone network Ghostnet is used to replace the CSPdarknet53 backbone network in YOLOv4. Compared with YOLOv4, it has fewer parameters and is lighter in weight, which is proposed by Huawei. When the features with common convolution are being extracted, some of the same features are merged with the network after convolution, thus reducing the amount of computation without reducing the accuracy.

    On the basis of replacing the backbone network, the deep separable convolution is used to replace the convolutional block of the neck network in YOLOv4. The deep separable convolution is further optimized by being divided into two simple steps and reducing the weight and computation amount. Although the previous modified network has improved the detection speed, the accuracy has decreased. In order to improve the accuracy without greatly increasing the calculation amount and weight, the number of layers of CBL convolutional module increases before and after the space pyramid pooling, and all the three layers are replaced with five layers to increase the ability of information extraction.

    In addition, better information extraction of the feature map at the end of the backbone network can improve the accuracy, so the feature extraction of the image and the information acquisition of the whole network in the image are required with the aim to improve the accuracy. In order to further improve the accuracy, KNN clustering algorithm is used to calculate the prior box for prediction so as to make better preparation for the subsequent training. The more similar the prior box is to the target box, the more accurate the network will be after training. Meanwhile, Mosaic data are used to enhance the recognition accuracy. The detection results of apple show that the modified network has a better recognition accuracy: compared with YOLOv4, the detection speed increases by 45.8%, the FPS reaches 35 frames, and the weight of the whole network reduces by 79.7%. Compared with the other algorithms introduced in this paper, the modified network is better in both accuracy and prediction speed. In comparison with the effect of the picture, the accuracy of the modified network frame selection is more accurate than that of the other networks, and the missed targets are also fewer than those of the other networks. In view of the above performance, the overall performance of the modified network is better than that of the original YOLOv4 and the other networks. The modified network improves the detection speed and reduces the weight file size, and can be better applied to the edge equipment such as picking robots with insufficient computing power and small storage space.

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    Electrical and electronic

    Hydrophobicity evaluation of composite insulators based on an improved Grab Cut algorithm

    2023, 37 (5):  218-227. 
    Abstract ( 130 )   PDF (3292KB) ( 94 )   Save
    In order to quickly and accurately identify the hydrophobicity of composite insulator skirts, this paper proposes a hydrophobicity evaluation method of composite insulators based on an improved Grab Cut algorithm. On the basis of Grab Cut, an adaptive contrast enhancement algorithm is introduced to solve the problem of uneven image illumination and an adaptive smoothing filtering algorithm is used to solve the problem of image noise. A droplet of 20 μL is dropped on the surface of the skirt. The improved Grab Cut algorithm is used to identify the droplet area of corona aging samples, natural contaminated silicone rubber samples, different hydrophobic silicone rubber samples and composite insulators under actual operating conditions. The results show that the algorithm can effectively reduce the image noise caused by the contamination of the surface area of the skirt during the operation of the composite insulators, and can accurately segment the droplet images from the composite insulator background, which verifies the effectiveness and reliability of the algorithm. It can also measure the change of the droplet area of both artificially accelerated aging and natural aging samples, and realize the evaluation of hydrophobicity of composite insulators in accordance with the static contact angle method.
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    Research on the application of IPSO-AP&O algorithm in MPPT control of the photovoltaic system

    2023, 37 (5):  228-235. 
    Abstract ( 114 )   PDF (3183KB) ( 98 )   Save
    Under uneven illumination conditions, the output characteristics of photovoltaic (PV) arrays exhibit multiple peaks, and the traditional maximum power point tracking (MPPT) methods are prone to local extreme values. In order to improve tracking speed and accuracy under complex shadows, this paper proposes an improved MPPT control method based on the improved particle swarm optimization and adaptive perturbation and observation (IPSO-AP&O) algorithm by combining the advantages of IPSO and AP&O. Specifically, IPSO adopts an adaptive inertia weight factor, which can fully search the objective function in different search stages, and then combines with AP&O to achieve stable output of the maximum power. The simulation results show that the proposed IPSO-AP&O algorithm reduces the iteration process of the traditional intelligent algorithms, and can quickly track the global maximum power point. Compared with other algorithms, it has fast and accurate dual tracking abilities when the illumination intensity changes abruptly. The tracking efficiencies in four scenarios are 99.86%, 99.91%, 87.63% and 99.79% respectively, which can better reduce the power loss caused by the change of external conditions of PV arrays. Moreover, the proposed MPPT control method can be applied to PV storage hybrid systems and has certain engineering practical value.
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    Research on slip control of electromagnetic coupling governors based on automatic disturbance rejection

    2023, 37 (5):  236-243. 
    Abstract ( 92 )   PDF (3337KB) ( 88 )   Save
    In order to improve the stability of the output speed of an electromagnetic coupling governor, this paper takes the electromagnetic coupling governor as the research object to analyze its dynamic characteristics. Firstly, this paper decouples the electromagnetic equation between the armature and the magnetic pole, performs the Clark-Park transform between the natural coordinate system and the rotational coordinate system of the motor, and derives its mathematical model. It also uses Matlab/Simulink to build a simulation model of the electromagnetic coupling governor. Then, it uses the first-order linear automatic disturbance rejection control (LADRC) technology to reasonably control the slip of the electromagnetic coupling governor. The simulation results show that LADRC has a better effect than the traditional PID control does, which improves the response speed and robustness of the slip control of the electromagnetic coupling governor. It also ensures the stability of the output speed when the load fluctuates, and improves the speed output performance of the electromagnetic coupling governor.
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    PC-STBC scheme for MIMO-PLC system

    2023, 37 (5):  244-252. 
    Abstract ( 117 )   PDF (2791KB) ( 128 )   Save
    A polarization code cascade space-time coding scheme for multiple-input and multiple-output power line communication systems is proposed to address the problem of poor system BER performance due to strong channel fading and great noise interference in power line communication. The information source is constructed as a polarization code by Gaussian, and then the polarization code is modulated into a symbolic and space-time block code for cascading. The simulation results show that the system BER performance of the polarization code cascade space-time block coding scheme is better than that of the space-time coding scheme, with a gain of about 7.2 dB in a power line impulse noise environment with a BER of 10-4 in the multi-input and multi-output power line communication system. When the system BER is 5×10-4, the system gain of the polarization code cascade space-time block coding scheme is about 0.2 dB, compared with the Turbo code cascade space-time coding scheme. By reducing the number of weak paths and pulse noise intensity, the cascade coding scheme shows a better anti-interference ability, and the system coding gain increases by a range of 0.2 dB to 0.5 dB more when the BER is below 10-3. In addition, due to the characteristics of polarization codes, the system BER performance can be further improved by decreasing the code rate or increasing the code length of the cascade coding.
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    Energy, power and environment

    Low-carbon economic dispatching of the integrated energy system of a carbon capture power plant considering Stackelberg game

    2023, 37 (5):  253-264. 
    Abstract ( 111 )   PDF (4722KB) ( 89 )   Save
    In order to reasonably distribute the interests of all parties in the comprehensive energy system and promote low-carbon economic operation of the system, this paper proposes an optimal scheduling model of the comprehensive energy system with a comprehensively flexible operation mode of a carbon capture power plant based on Stackelberg game. First of all, in order to realize low-carbon economic operation of the system, a combined operation model with the comprehensively flexible operation mode of carbon capture power plant-power to gas-gas turbine is constructed under the game framework, and a demand side response strategy is added to the user side. Secondly, in order to mobilize the initiative of the three parties of sources, load and storage, a multi-stakeholder model is established, with operators being the leaders and energy storage providers, producers and users being the followers. A profit model of each stakeholder is also constructed. Finally, CPLEX solver and double mutation differential evolution algorithm are combined to solve the model. Taking an industrial park in northern China as an example, the results show that, compared with the traditional model, the proposed model and algorithm can effectively reduce carbon emissions and operating costs of the comprehensive energy system.
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    Algorithm research on health state of a lithium battery by integrating the features of electrochemical impedance and incremental capacity curves

    2023, 37 (5):  265-272. 
    Abstract ( 134 )   PDF (2030KB) ( 198 )   Save
    As the energy power of electric vehicles, batteries are the most critical component in the performance and safe operation of electric vehicles, whose state of health (SOH) is of great significance to improve the safety and availability of new energy electronic equipment. Aiming at safe operation of lithium-ion batteries, this paper proposes a health state prediction algorithm based on feature fusion. The framework combines the health features of electrochemical impedance spectroscopy (EIS) and incremental capacity analysis (ICA), uses convolutional neural network (CNN) and the improved long short term memory (LSTM) network to establish the mapping relationship between features and state of health, and uses quantum particle swarm optimization (QPSO) algorithm to optimize the hyperparameters of the hybrid network structure. Finally, the NASA PCoE dataset is used to verify the accuracy and reliability of the method.
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    Research on heat dissipation performance of nuclear DCS chassis and analysis of the influencing factors

    2023, 37 (5):  273-282. 
    Abstract ( 118 )   PDF (6703KB) ( 122 )   Save
    In order to study heat dissipation performance and the influencing factors of nuclear safety DCS chassis, this paper establishes a finite element model of a nuclear DCS chassis and carries out thermal simulation analysis. The research results show that the maximum temperature of U1 chip at the stable stage is 90 ℃, which is basically consistent with the actual measured temperature of 87.9 ℃. Therefore, the finite element model established in this study is effective and reliable. The surface temperature of the chassis is influenced by the function modules installed inside. The higher the thermal power consumption of the functional modules is, the higher the surface temperature is. At the position of the same function module, the temperature at the top surface of the chassis is higher than that at the bottom surface. In the state of natural convection, air flows in from the bottom surface and out from the top surface, and the air flow velocity at the top surface is greater than that at the bottom. Furthermore, by changing heating method, ventilation rate, air intake method, air volume and other factors to study the effect on heat dissipation performance of the chassis, the results show that the best thermal transmission path starts from the chip to the thermal pad, and then the heat transfers to the finned shell and finally to the chassis. Compared with natural cooling, the surface temperature of the key components reduces by 55.4 ℃. There is a positive correlation between the ventilation rate and the heat dissipation performance of the chassis. When the ventilation rate of the chassis increases, the temperature of the components shows an approximately linear decline. When the fan is installed above the chassis to absorb air, the temperature of the key components is 59.8 ℃. In contrast, when the fan is installed below the chassis to supply air, the temperature is 63 ℃, so the fan installed above is a better choice. The heat dissipation performance of the chassis is affected by the airflow of the fan. The larger airflow of the fan is, the better the heat dissipation performance of the chassis is.
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    An improved cascaded ADRC control method for the electromechanical servo system

    2023, 37 (5):  283-290. 
    Abstract ( 95 )   PDF (2594KB) ( 153 )   Save
    Aiming at the problem that the conventional PID control effect of the aerospace electromechanical servo system decreases due to the change of load characteristics, this paper applies active disturbance rejection control (ADRC) to the aerospace electromechanical servo system. A mathematical model is established according to the characteristics of the aerospace servomechanism. an improved cascaded ADRC control method is proposed for the characteristics of the servo cascade system. The unknown interference of the three subsystems is estimated and compensated by three extended state observers, which reduces the complexity of the system and effectively improves the system control performance of the current loop and the speed loop. The simulation results show that, compared with the conventional position loop ADRC control method, the cascaded ADRC control method not only reduces the difficulty of parameter setting to a certain extent, but also effectively improves the anti-jamming ability and the control performance of the system.
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    Study on simulation calculation of wind deviation prevention of 220 kV composite insulators

    2023, 37 (5):  291-297. 
    Abstract ( 98 )   PDF (3287KB) ( 209 )   Save
    Taking a 220 kV wire in Ningxia with frequent wind deviation faults as an example, this paper firstly establishes wind deviation models of composite insulators by using concentrated load and distributed load methods respectively, and analyzes the differences between the two methods. Secondly, based on the models, simulation calculation models of wind deviation of composite insulators plus wires under wind deviation prevention measures such as splayed strings, V-strings, stay wires and heavy hammers are established, and compares the wind prevention effects of the different measures. The results show that the difference range of wind deviation results obtained through the concentrated load method and the wind deviation load method at different wind speeds is within 8% to 48.57%. V-shaped composite insulator strings and stay wires show the best wind deviation prevention effects, but their application range is limited, with the former limited by the position of use and the latter by floor width. The wind deflection angle of the splayed composite insulator string decreases with the increase of the insulator angle γ, but its wind deflection prevention mainly depends on the reduction of the equivalent insulator length. The wind deviation prevention effect of the heavy hammers is limited, which needs to be combined with other measures.
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    Study on the knock prediction model of two-stroke ignition aviation kerosene engines

    2023, 37 (5):  298-307. 
    Abstract ( 125 )   PDF (4669KB) ( 126 )   Save
    The knock prediction of two-stroke ignition aviation kerosene piston engines is studied in this paper. Based on 3-Arrhenius equation, this paper proposes a two-component blended knock prediction model. According to the experimental data of aviation kerosene combustion, a combustion model of aviation kerosene is developed and checked by using GT-Power software. The temperature of the end mixture gas required by the knock prediction model is obtained through one-dimensional performance simulation. The prediction performance of the blended knock prediction model and the single knock prediction model is evaluated through the engine knock test data. The results show that the standard errors between the predicted knock onset angle and the experimental knock onset angle are 1.19°CA and 3.23°CA respectively for the blended knock prediction model and single knock prediction model. The blended knock prediction model can identify the low-pressure region at the initial stage of combustion, and it has a good response to the sudden increase of pressure in the cylinder during the knock cycle, which shows a good knock prediction performance.
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    Pharmaceutical·Biological Engineering

    Preparation and properties characterization of natural vascular matrix/polycaprolactone composite vascular scaffolds

    2023, 37 (5):  308-317. 
    Abstract ( 119 )   PDF (3687KB) ( 158 )   Save

    Vascular diseases are one of the leading causes of death in China and even in the global population. Currently, common vascular grafts can be broadly divided into autologous vascular grafts, xenogeneic vascular grafts as well as vascular tissue engineering. Autografts are the gold standard in a clinical surgery, but they are unfavorable for the subsequent treatment of patients because of repeated surgeries and poor sources. In addition, easily producing rejection reaction with the body to cause damages due to poor biocompatibility, xenogeneic vascular transplantation not only has immunogenicity, but may also spread diseases to cause infection. Therefore, it is difficult to meet the requirements of vascular transplantation. However, the rapid development of tissue engineering technology provides a new solution for the treatment of vascular diseases.

    At present, all the vascular scaffolds developed at home and abroad have their advantages and disadvantages, which often require multiple composite materials to achieve advantage complementation. Traditional decellularized scaffolds may have lower cell permeability due to their dense extracellular matrix network. Recently, it has been shown that decellularized vascular matrix gel (DVMG) is a promising material that not only has the advantage of decellularized vascular matrix (DVM), but can also control the mechanical properties of vascular scaffolds by changing the concentration or cross-linking density of hydrogels. This study complexes DVMG with polycaprolactone (PCL), and the resulting composite scaffolds can retain the vascular regenerative properties of the native vascular matrix and overcome the deficiency its rapid degradation, expanding its applications in the field of tissue engineering. DVM powder is obtained through decellularization and delipidation of fresh porcine aorta in a series of treatments, after which the DVMG is enzymatically dissociated, the PCL solution configured with glacial acetic acid is mixed with DVMG with different proportions, and the molds are repeatedly wrapped by the mixed solution after being cooled at a room temperature to obtain different groups of composite vascular scaffolds.

    In this study, a total of four groups of DVMG/PCL scaffolds are prepared. The scaffolds are observed by a scanning electron microscope (SEM) to have a relatively uniform surface with obvious pores in the cross-sectional structure, which is beneficial to cell adhesion and migration. The tensile modulus values of pure PCL scaffold and the other three scaffolds with a ratio of DVMG:PCL at 1∶1,1.5∶1 and 5∶1 detected by mechanical tensile experiments are in an order of 49.00±9.52 MPa, 46.29±3.08 MPa, 38.77±2.07 MPa and 31.18±2.80 MPa respectively. The in vitro degradation experiments show that all of the four groups of scaffold materials have some degradation abilities, and the degradation rate is related to the content of DVMG. By changing the ratio of DVMG to PCL, composite vascular scaffolds with different mechanical properties and degradation properties can be produced. Compared with the pure PCL scaffold, the higher the content of DVMG in the composite scaffold is, the lower the stiffness of the scaffold is, and the faster the degradation rate is, which shows a better overall performance of the DVMG/PCL scaffolds. The findings are of great reference value to the further application of DVM and DVMG and the improvement of the biological response of polymeric materials.

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    Pharmaceutical care of patients with refractory cancer pains treated with IDDS

    2023, 37 (5):  318-323. 
    Abstract ( 92 )   PDF (1270KB) ( 104 )   Save
    Objective: This paper aims to explore the role of clinical pharmacists of pain specialty in the treatment of refractory cancer pains by implanting intrathecal drug delivery systems (IDDS). Methods: A clinical pharmacist participates in a case of clinical treatment of a patient with refractory cancer pains by implanting IDDS, evaluates the nature of the patient’s pains, assists the doctor to formulate an individualized dosing plan from the aspects of analgesic drug selection, drug dose, adverse drug reactions and interactions, and closely observes the treatment effect of the patient’s pains and the concurrent symptoms. In this way, this paper puts forward reasonable suggestions for the clinical drugs, and carries out pharmaceutical care for the patient and provides medication education. Results: The patient’s pain control is satisfactory, and the drug treatment is comprehensively optimized without any serious adverse drug reactions. Conclusion: By conducting dynamic and comprehensive pain assessment on cancer pain patients, the clinical pharmacist of pain specialty participates in analgesic plan formulation and adverse reaction monitoring. Therefore, it is advised to help optimize the intrathecal analgesic medication plan from the perspective of rational medication, improve the medication compliance of patients and ensure their medication safety
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    Effect of GnT-IVa on the regulation of geniposide in the glycosylation of glucose transporter 2 and glucose uptake in pancreatic beta cells

    2023, 37 (5):  324-330. 
    Abstract ( 87 )   PDF (2135KB) ( 74 )   Save
    N-acetylglucosamine transferase-4a (GnT-IVa) is an indispensable glycosyltransferase for the formation of N-glycan branch complex of glucose transporter 2 (GLUT2) in pancreatic beta cells, which sits the N-glycan branch complex on the surface of cell membranes to perform its normal physiological functions. The previous work of this research group indicates that geniposide can rapidly regulate the glycosylation of GLUT2 and glucose uptake in pancreatic beta cells, but whether GnT-IVa is directly related to it is still not clear. This paper firstly uses siRNA to interfere GnT-IVa expression of INS-1 cells, and then analyzes the effect of geniposide on the glycosylation of GLUT2, glucose uptake and metabolism, and glucose-stimulated insulin secretion (GSIS). The results reveal that, in INS-1 cells interfered by GnT-IVa genes, the effects of geniposide on the glycosylation of GLUT2, glucose uptake, ATP production and GSIS are significantly attenuated. All these findings indicate that GnT-IVa may play an important role in geniposide regulating the glycosylation of GLUT2, glucose uptake and metabolism, and GSIS in pancreatic beta cells.
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    Prokaryotic expression and identification of des-γ-carboxyprothrombin protein

    2023, 37 (5):  331-336. 
    Abstract ( 92 )   PDF (1748KB) ( 94 )   Save
    To achieve efficient expression of des-γ-carboxyprothrombin (DCP) in a prokaryotic system, this paper refers to the CDS sequence of DCP gene published in GenBank (accession number LX095963). Based on a correct amino acid sequence of the DCP protein, the codon of the DCP gene is optimized. The CDS sequence gene is synthesized and fused into pET28a(+) plasmid to construct pET28a(+)/DCP recombinant plasmid. Then, the plasmid is transferred into the receptor state BL21(DE3) for induction expression, and the DCP protein is purified by a nickel column to conduct purity measurement, concentration determination and western blot analysis of the recombinant protein DCP. The results show that the recombinant plasmid has a double enzyme cut band at 1 875 bp, which is sequenced to match its optimized gene sequence. The highest expression of the DCP protein is obtained when the recombinant bacteria are induced at an IPTG final concentration of 0.8 mmol/L for 6 hours at 25 ℃. After nickel column purification, the recombinant protein DCP has a high purity, the concentration of which reaches 1.04 mg/mL. As expected, there is a clear protein band at 72 kD. It shows that the recombinant protein DCP is successfully expressed in E. coli system, which provides reagent reference for the subsequent study of DCP detection methods.
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