上海工程技术大学学报

Modeling and simulation of CAST-MBBR process for wastewater treatment

ZHANG Lingli, GU Dungang, LU Jiaqi, ZHANG Nan, HU Lijiang, LI Guanghui

2023, 37(2): 105-112. doi: 10.12299/jsues.22-0149

Abstract:
Based on cyclic activated sludge technology (CAST) and moving-bed biofilm reactor (MBBR), mathematical modeling and simulation of CAST-MBBR process for a real wastewater treatment plant in Zhejiang Province was carried out. Based on the process mechanism, a semi-empirical biofilm model was embedded into the activated sludge model No.1 to describe the biochemical process of carbon and nitrogen removal in CAST-MBBR. It is then combined with a double exponential model describing particle sedimentation to form a complete CAST-MBBR process model, and a conversion method between inlet and outlet water quality and model components was established. The key parameters that have a significant impact on effluent indicators were screened through sensitivity analysis and adjusted. The calibrated model was verified by using the influent and effluent water data of the wastewater treatment plant throughout the year. The result shows that the simulated effluent data can agree well with the measured data, indicating that the modeling method can be effectively applied to the simulation of CAST-MBBR process.

[Abstract](196) [FullText HTML] (80) [PDF 939KB](510)

Preparation of photocatalytic ozonation SiC foam and its application in levofloxacin degradation

ZOU Jingtao, LI Xuankun, YANG Jie, WEI Mingfei, ZHANG Wenqi, LI Guanghui

2023, 37(2): 113-119. doi: 10.12299/jsues.22-0189

Abstract:
To solve the problem of environmental pollution caused by the difficult degradation of antibiotics, Ce-TiO₂/SiC foam was prepared, levofloxacin (Levofloxacin, LEV) was chosen as the target pollutant, and a photocatalytic ozonation coupling system (Ce-TiO₂/SiC + LED + O₃) was studied. The results show that the coupling system can effectively degrade LEV, the LEV removal was 99% and the chemical oxygen demand (COD) removal was as high as 85.9%. The coupling system showed a good synergistic effect, and its first-order reaction kinetic rate constant was greater than the sum of ozonation (O₃) and photocatalysis (Ce-TiO₂/SiC + LED). In addition, the stability experiment of Ce-TiO₂/SiC foam showed that the photocatalytic ozonation activity is basically unchanged after five reuses.

[Abstract](99) [FullText HTML] (52) [PDF 1547KB](303)

Research on Enhanced catalytic soot combustion performance over NiO/Co₃O₄ within mesoporous nanosheets

SUN Honghua, SUN Biao, LI Peng, QIU Jianqiang, ZHANG Nianchen, WANG Jinguo, WANG Xiutong

2023, 37(2): 120-127. doi: 10.12299/jsues.22-0064

Abstract:
A series of NiO/Co₃O₄ catalysts within mesoporous nanosheets, synthesized by a facile hydrothermal combining wet-impregnation route, have been developed to catalyze diesel soot combustion. Results attest that, when the molar ratio of Ni/Co reached 12%, the catalyst of 12NiCo exhibited the optimal catalytic soot combustion performance, giving T_m of 347 ℃ and 100% CO₂ selectivity, which can be chiefly credited to the synergetic effect of the following factors. Firstly, the unique 2D nanosheets together with high surface area enlarged the contact interface of catalyst-soot particles. Secondly, abundant mesopores within nanosheets favored the significant decrease in mass transfer resistance and then in turn promoted the adsorption and diffusion of gas reactants. Thirdly, the enhanced reducibility by introducing NiO not merely facilitated the adsorption and activation of oxygen species to form active oxygen species, but also benefited NO oxidation to produce NO₂ with higher oxidative capability, thereby improving catalytic soot combustion performance remarkably. In addition, 12NiCo also presented the excellent reusability, demonstrating good potential in future practical applications.

[Abstract](108) [FullText HTML] (50) [PDF 2663KB](433)

Effects of different extraction methods on polysaccharide content and antioxidant activity of northern Ban-Lan-Gen

WANG Yuting, PENG Yuanyuan, LIU Xia, CHEN Xueqin, ZHAO Linjing

2023, 37(2): 128-132. doi: 10.12299/jsues.22-0054

Abstract:
The effects of different extraction methods on polysaccharide content and antioxidant activity of northern Ban-Lan-Gen were investigated. The polysaccharide of northern Ban-Lan-Gen was extracted by conventional reflux extraction method and ultrasonic assisted reflux extraction method. The total polysaccharide content was determined by phenol-sulfuric acid spectrophotometry. DPPH free radical and ABTS⁺ free radical scavenging assays were used to evaluate their antioxidant activity in vitro. The results show that the yield of polysaccharide extracted by ultrasonic assisted reflux extraction method was 40.07%, which was significantly higher than that by conventional reflux extraction method (13.42%). The phenol-sulfuric acid method has high precision, repeatability, stability and good recovery, which can be used to study the polysaccharide content of northern Ban-Lan-Gen prepared by different extraction methods. The polysaccharide content of ultrasonic assisted reflux extraction method was 22.3% higher than that of conventional reflux extraction method, and the scavenging effects of DPPH· and ABTS⁺· was significantly better than that of conventional reflux extraction method. The results provide a reference for the application of ultrasonic technology in the extraction of polysaccharide of northern Ban-Lan-Gen.

[Abstract](101) [FullText HTML] (51) [PDF 788KB](291)

Preparation and electromagnetic shielding performance study of MXene/polyaniline bulk composites

GUO Rui, ZHU Meiling, REN Yujie, WANG Yiding, ZHENG Qi

2023, 37(2): 133-139. doi: 10.12299/jsues.21-0314

Abstract:
Electromagnetic inference (EMI) shielding materials are vital for the reduction of EM radiation pollution, in which conductive polymer-based composites have attracted wide attentions. Herein, MXene/PANI bulk composites were successfully prepared by spark plasma sintering, in which MXene was chosen as the functional 2D materials evenly dispersed in the PANI matrix through ultrasonic, mechanical agitation and freeze-drying methods. Consequently, MXene with high electrical conductivity and lamellar structure effectively improves the EMI shielding performance of PANI. When the content of MXene is 40%, the composites achieve the optimal EMI shielding characteristics of 24 dB in the range of 8.2~12.4 GHz.

[Abstract](285) [FullText HTML] (342) [PDF 1614KB](237)

Study on preparation and cycling performance of anode materials for SiC@CNFs lithium-ion battery

WANG Xin, WANG Lili, LIU Ye

2023, 37(2): 140-147. doi: 10.12299/jsues.22-0038

Abstract:
A SiC-enhanced carbon nanofiber composite (SiC@CNFs) structure was prepared by electrospinning technology combined with carbonization process. The results of TGA, XRD, XPS and SEM show that the mass fraction of SiC particles is 62%, and it is evenly distributed on the surface of CNFs. The lithium-ion battery anode material prepared by this structure not only retains the high electrical conductivity of CNFs, but also obtains the enhanced structural toughness of SiC. The electrochemical performance test results show that the capacity retention rate of the lithium-ion battery anode material is as high as 134.01% after 500 cycles, much higher than that of CNFs. Moreover, the electrochemical impedance value of the structure changes less and the conductivity of SiC@CNFs remains good. SiC@CNFs structures prepared by electrospinning technology serve as lithium-ion battery anode, with low production cost, controllable structure and stable performance, which is a beneficial supplement to the current battery cathode materials.

[Abstract](133) [FullText HTML] (58) [PDF 1656KB](162)

Design of active disturbance rejection controller for quadrotor unmanned aerial vehicle based on equivalent sliding-mode control method

HU Junyao, TONG Dongbing

2023, 37(2): 148-154. doi: 10.12299/jsues.22-0124

Abstract:
An active disturbance rejection controller (ADRC) based on equivalent sliding-mode control method was proposed to solve the stability problem of quadrotor unmanned aerial vehicle (UAV) with disturbances and uncertainties. According to the transformation of the body coordinate system and ground coordinate system, combined with Newton's second law and Newton-Euler formula, the dynamic model of UAV was constructed. An extended state observer was designed to restore the state of the system and estimate all disturbances and uncertainties of the system, in order to achieve rapid error convergence and improve estimation accuracy. Based on the ADRC, the concept of an equivalent sliding-mode controller was proposed, and the control output was divided into the equivalent control term and the switching robust control term. Combined with the non-singular terminal sliding-mode control, the singular problem was avoided. Through the Lyapunov stability theory, it is proved that the designed ADRC can achieve system asymptotic stability. Finally, the active disturbance rejection performance and robustness were verified by a numerical simulation example.

[Abstract](233) [FullText HTML] (75) [PDF 1195KB](166)

Power loss analysis and cooling design of flat wire motor winding for vehicle electrical motor

CHEN Lin, YAN Yecui

2023, 37(2): 155-163. doi: 10.12299/jsues.22-0269

Abstract:
The flat wire motor for Electric Vehicles have the characteristics of small size, light weight and high power density. However, with the development of high-speed motor, the AC loss of flat wire motor becomes larger, and its thermal rise performance is different from the traditional circular wire motor, so it is necessary to design a cooling method suitable for it. Firstly, a two-dimensional finite element model of a high speed flat permanent magnet synchronous motor for new energy vehicles was established, the influences of the size, layer number and parallel branches number of the flat conductor on the AC loss of the motor under the driving cycle of WLTC-3 were analyzed, and the optimal conductor size and winding connection mode were obtained. Then on the basis of loss analysis, according to the temperature field distribution of the motor, the optimal cooling method of oil cooling has been designed, which reduces the temperature rise and improves the reliability of the motor operation.

[Abstract](136) [FullText HTML] (88) [PDF 2376KB](173)

Path following control of unmanned vehicle based on improved model predictive control

ZHOU Yipeng, LI Cong, YANG Wei

2023, 37(2): 164-172. doi: 10.12299/jsues.22-0251

Abstract:
In order to improve the path following accuracy and stability of unmanned vehicles, a parameter adaptive model predictive control (MPC) method based on particle swarm optimization (PSO) and Gaussian process regression (GPR) was proposed. By using PSO to optimize MPC parameters offline and GPR to generate optimal parametric surfaces, the path following performances of unmanned vehicles can be improved under various working conditions. The simulated results show that the improved MPC method achieves good path tracking accuracy while maintaining vehicle stability throughout the path following process. Finally, the effectiveness of the improved MPC method was verified on a real unmanned vehicle.

[Abstract](190) [FullText HTML] (58) [PDF 2594KB](164)

Aerodynamic numerical simulation of four-axis vertical take-off and landing jet unmanned aerial vehicle

YAO Baiqiang, CHEN Saixuan

2023, 37(2): 173-178. doi: 10.12299/jsues.21-0315

Abstract:
Based on the strict requirements of high maneuverability, high load and high dynamic response of unmanned vertical take-off and landing (VTOL) aircraft, a four-axis VTOL jet unmanned aerial vehicle (UAV) was researched and designed. According to the three basic equations of fluid mechanics and turbulence k−ε equation, the aerodynamic numerical simulation was carried out to determine the calculation domain of the external flow field during UAV flight. ICEM CFD software was used to divide the external flow field into hybrid unstructured grids. The flow field boundary conditions were set in the Fluent solver, and the turbulence model was taken as the basic model. The aerodynamic performance of the whole UAV were simulated and solved. The resistance coefficient, flow velocity distribution, pressure distribution and turbulent kinetic energy of each part of the UAV surface were obtained, and the aerodynamic characteristics were analyzed. The analysis shows that there are problems of large kinetic energy loss and high resistance coefficient at the top, tail, lower surface head and jet bracket of the upper surface of the UAV. According to the simulation results, the aerodynamic modeling of the above parts of the UAV was optimized. The results show that the total resistance coefficient of the UAV is reduced from the original 0.165 to 0.121, and the surface pressure, flow velocity and turbulence of the UAV are effectively improved. After optimization, the aerodynamic characteristics are better and the aerodynamic modeling is in line with the design concept.

[Abstract](110) [FullText HTML] (61) [PDF 2531KB](197)

Dynamic modeling and analysis of flexure mechanism in two-dimensional micro motion stage

LIU Hao, LAI Leijie

2023, 37(2): 179-183. doi: 10.12299/jsues.22-0274

Abstract:
A two degree of freedom translational decoupling parallel micropositioning stage based on parallel flexure mechanism was proposed. A compound double parallel four-bar flexure mechanism module was adopted in the stage, and structural symmetry constraints were introduced to eliminate the coupling between shafts and parasitic displacement, and translations in X and Y directions were achieved. The stiffness matrix method was used to analyze the parallel flexure mechanism in theory. According to the observation method, the overall stiffness matrix of the micropositioning stage was established, and the differential equations of motion of the system were obtained, and the natural frequencies of each order of the system were deduced. The modal analysis of the micropositioning stage was carried out by using the finite element method, and the natural frequency and mode shape of the micropositioning stage were obtained. Through theoretical analysis, finite element calculation and experimental test, the consistency of the results shows the correctness of theoretical analysis and the effectiveness of stiffness matrix analysis.

[Abstract](111) [FullText HTML] (47) [PDF 1707KB](43)

Design and simulation analysis of a flux focusing magnetic gear with Z-type pole-pieces

ZHANG Bangjing, ZHU Zina, LI Kaiyuan

2023, 37(2): 184-189. doi: 10.12299/jsues.22-0004

Abstract:
A flux focusing magnetic gear with Z-type pole-pieces (ZP-FFMG) was presented and investigated. In this magnetic gear structure, the proposed Z-type pole-pieces can couple the magnetic flux of the end face and cylindrical face of rotors. The 3D simulation shows that there are axial and radial magnetic flux components in the ZP-FFMG, which are helpful to torque transmission. A comparative analysis of traditional flux focusing magnetic gear (FFMG) and ZP-FFMG was given. The results show that compared with the traditional FFMG, the transmission torque of the ZP-FFMG is increased by 42%, the torque density is increased by 15 kN·m/m³, and the magnetic flux density is also improved.

[Abstract](98) [FullText HTML] (47) [PDF 1806KB](58)

Recognition method of sEMG gesture based on improved deep forest

HUANG Sheng, MAO Jian

2023, 37(2): 190-197. doi: 10.12299/jsues.22-0173

Abstract:
In order to improve the accuracy of gesture recognition based on surface electromyography (sEMG), an improved deep forest combined hand motion recognition method was proposed. The extreme gradient boosting (XGBoost) tree was introduced into the deep forest model to form the cascade structure of deep forest together with the random forest and the complete random forest. The deep forest model integrates three different tree-based classifiers at each level, a total of four decision forests including a random forest, an extreme random forest and two extreme gradient boosting trees. The classification performance was improved by using the complementarity between different learning algorithms. In order to evaluate the performance of the model, the sEMG signals of 4 healthy subjects were collected for the verification experiment of hand action recognition, and compared with random forest, support vector machine, one-dimensional and two-dimensional convolutional neural networks algorithms. The result shows that the average recognition accuracy of the method for 16 commonly used hand actions is 94.14%, and the classification accuracy of sEMG signals is high.

[Abstract](130) [FullText HTML] (80) [PDF 948KB](199)

Optimization of real-time assembly man-hours scheduling based on digital twin

WU Xinyu, ZHANG Meihua, ZHANG Liqiang

2023, 37(2): 198-206. doi: 10.12299/jsues.22-0157

Abstract:
Based on digital twin, a real-time assembly man-hours workshop scheduling model was proposed, considering the uncertainty of assembly man-hours in the process of product customization and frequent dynamic disturbances in the assembly workshop. The overall architecture of assembly workshop scheduling based on digital twin was constructed. Radio frequency identification (RFID) technology was used to collect real-time working hours data of physical assembly workshops, and the real-time assembly working hours were processed by using the improved Rete algorithm. A mathematical model of assembly workshop scheduling based on real-time assembly man-hours was established, and an improved artificial fish swarm-taboo algorithm was used to solve the model, so as to realize the scheduling optimization of the real-time assembly man-hours workshop. The empirical result shows that the model algorithm has certain feasibility and superiority in real-time assembly man-hours workshop scheduling.

[Abstract](114) [FullText HTML] (55) [PDF 1503KB](47)

Research on refrigeration cooling and temperature control of thermoelectric devices for cylindrical battery module

WEI Peng, YI Zhaozang, ZHANG Hengyun, SUN Haitao, ZENG Shuzhen, CHEN Yun

2023, 37(2): 207-214. doi: 10.12299/jsues.22-0037

Abstract:
Based on the Peltier effect, a method of real-time controlling battery temperature through thermoelectric device (TED) was proposed. It integrated the refrigeration and heating functions of TED, has a good temperature control effect, and can meet the thermal management needs of battery modules. The battery module consists of 3×5 rows of cylindrical batteries filled with foam metal composite phase change materials, and the thermoelectric device was arranged on the large face of the battery module shell. Compared with the liquid cooling experiment, thermoelectric refrigeration could significantly reduce the temperature of the battery module at 1~5 W of single cell heat generation power, and control the temperature difference of the module within 5 ℃. The temperature control experiment further shows that the TED controlled by the thermostat in real-time can effectively stabilize the module temperature and control the temperature fluctuation within 2~3 ℃. In addition, a one-dimensional thermal resistance network was established, and the thermal performance of TED was analyzed based on steady-state theory. The result shows that under the refrigeration condition, the cold junction temperature of TED is decreasing first and then increasing with increasing of its current, and the hot junction temperature is proportional to the TED current.

[Abstract](109) [FullText HTML] (49) [PDF 1827KB](188)

2023 Vol. 37, No. 2