上海工程技术大学学报

Research Progress of Conductive Metal-Organic Frameworks in Thermoelectric Materials

WU Xin, ZHANG Fan, ZHENG Qi, WANG Lianjun

2021, 35(1): 1-8.

Abstract:
Metal-organic frameworks (MOFs) are highly-ordered and crystalline porous materials. Through a series of experimental design strategies, MOFs with high conductivity can be constructed , which is a great potential thermoelectric materials. The research progress of conducting MOFs in the field of thermoelectric materials were reviewed from the structure, conduction mechanism and thermoelectric applications of conducting MOFs. Meanwhile, the challenges and development direction of conducting MOFs in the field of thermoelectric materials were summarized, which can provide a reference for the development of new MOFs-based thermoelectric materials.

[Abstract](267) [FullText HTML] (270) [PDF 1030KB](159)

Study on Microstructure and Fatigue Properties of 6005 Aluminum Alloy Lap Joint

BAI Yishan, YANG Shanglei, ZHU Minqi, FAN Cong

2021, 35(1): 9-14.

Abstract:
Metal inert-gas (MIG) welding was used to conduct lap welding experiments on 6005 aluminum alloy. The microstructure and microhardness of the welded joint were observed. The results show that the intergrowth crystal appears in the fusion zone, the equiaxed crystal is dominant in the weld center, and the grain coarsening has occurred in the heat affected zone (HAZ). The Vickers hardness (HV) of the weld zone is 64.5, and that of the base metal zone is 89.6, and the joint appears obvious softening zone. The fatigue strength of the welded joint is only 21.41% of the base material in the fatigue performance test, and the fatigue fracture of the welded joint is a mixed fracture of ductile fracture and dissociative fracture. By analyzing the mechanism of fatigue crack propagation, it is concluded that the crack propagates in a “Z” shape along the 45° direction under the condition of crack tip passivation and loading stress cycle.

[Abstract](265) [FullText HTML] (179) [PDF 1416KB](135)

Study on Preparation and Properties of Graphene/Carbon Fiber Waterborne Electrothermal Coatings

XU Jinglu, CHEN Jinmin, WEN Shaoguo, WANG Yan, CHEN Yabo, WANG Changrui, WANG Jing

2021, 35(1): 15-21.

Abstract:
Electrothermal coating is a kind of functional coating which can directly convert electric energy into heat or radiation energy on the basis of conductive coating. A waterborne epoxy two-component thermal coating system with modified carbon fiber and graphene as conductive filler was studied. Scanning electron microscopy (SEM) was used to characterize the surface and section of the coating. It was found that the carbon fibers were evenly distributed in the coating, forming a good conductive and heat transfer network.The thermal conductivity test results show that the thermal conductivity coefficient of the coating is 0.40 W / (m·K). The temperature rise curve of the coating increased regularly in three stages, and reached the peak value in 15~28 min, and the theoretical thermal efficiency reached 63.02%. The safe voltage of the coating is 24 V, and it has good insulation performance, which can guarantee the use safety.

[Abstract](267) [FullText HTML] (205) [PDF 3601KB](124)

Influence of Process Parameters on Microstructure and Microhardness of TC4 Joints

LUO Peng, CHENG Qiran, GUO Jingang, WEN Hubo, ZHU Chufan, SHI Haichuan

2021, 35(1): 22-27.

Abstract:
TC4 titanium alloy was vacuum brazed with Ti-Zr-Cu-Ni amorphous brazing alloy, and the effects of different holding times on brazed joints were investigated. The optical microscope (OM), scanning electron microscope (SEM), energy data spectrometer (EDS) and micro-hardness tester were used to analyze the microstructure and mechanical properties of the joints. The results show that the main microstructure of the weld was α-Ti and β-Ti, and with the increase of holding time, the weld zone is gradually thickened and the microstructure is gradually coarse. When the holding time was 40 min, the micro-hardness of the weld was the largest, the average hardness (HV) was 328, and the maximum hardness was 335.

[Abstract](147) [FullText HTML] (124) [PDF 1280KB](112)

Analysis of Correlation Between Fiber Breaking Strength and Size Based on Generalized Two-Parameter Weakest Chain Statistical Model

ZHU Yuyang, ZHAI Jianguang, GAO Chun, LU Huiqin

2021, 35(1): 28-32.

Abstract:
In order to explore the correlation between fiber breaking strength and size, an improved generalized two-parameter weakest chain statistical model was used to uniformly process the breaking strength data of polyacrylonitrile-based (PAN-based) carbon fiber and jute fiber under different gauge lengths. An exponential parameter β was introduced to characterize the degree of deviation between the actual spatial distribution of defects and the ideal uniform spatial distribution conditions. By taking fiber breaking strength and size as statistical parameters, the obtained fiber failure function can collectively reflect the influence of fiber breaking strength and size on the probability of fiber failure, and better describe the correlation between fiber breaking strength and size.

[Abstract](163) [FullText HTML] (172) [PDF 798KB](147)

Research Progress of Graphene Reinforced Titanium Matrix Composites

WAN Zhaomei, LI Jiuxiao, HOU Shuluo, YANG Dongye

2021, 35(1): 33-36, 42.

Abstract:
Graphene can improve the properties of titanium matrix composites by adding graphene as reinforcement phase. Through the literature review, the preparation methods and related properties of graphene reinforced titanium matrix composites were introduced, and researches on interface structure and reinforcement mechanism were summarized. Finally, the future development trend of graphene reinforced titanium matrix composites was prospected.

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Research on Thermal Performance of Neoprene Diving Gloves

ZHANG Yongyang, CONG Shan

2021, 35(1): 37-42.

Abstract:
The maximum temperature difference method and regression analysis method were used to study the thermal insulation performance of neoprene diving gloves by comparing the palm temperature changes before and after wearing neoprene diving gloves and sponge diving gloves. The results show that the palm temperature loss rate of sponge diving gloves is lower than that of neoprene diving gloves before entering the water. After entering the water, the palm temperature loss rate of neoprene diving gloves is lower than that of sponge diving gloves, and the thermal insulation performance is better. The results of work efficiency expansion experiment showed that there is a linear relationship between palm temperature and bead throwing time. Before entering the water, there is no significant difference in work efficiency between wearing neoprene diving gloves and sponge diving gloves. After entering the water, the work efficiency of neoprene diving gloves is significantly higher than that of sponge diving gloves. The research results can provide a reference for underwater workers to choose diving gloves, and also provide a theoretical basis for expanding the application range of neoprene materials in diving products.

[Abstract](135) [FullText HTML] (149) [PDF 801KB](84)

Principle and Application of Local Knitting

WANG Linxia, KE Baozhu

2021, 35(1): 43-47.

Abstract:
Local knitting technology has been widely used in knitting products because of its advantages of low-cost, high speed and high efficiency. By summarizing the current research literatures, the principle and classification of local knitting were described, the conventional and the innovative applications of local knitting process were introduced, and problems existing in the application of local knitting process at the present stage were analyzed, which has certain reference value for the forming process design of knitting products.

[Abstract](185) [FullText HTML] (266) [PDF 1028KB](101)

Research on Inhibition Effect of Low Temperature and Short Illumination Time on Algal Growth

ZHANG Long, WANG Chun, ZHOU Ye, QI Leiqiang, GAO Feng, XU Jun

2021, 35(1): 48-52.

Abstract:
Algal breeding in water supply system bring a lot of harm to the production process of drinking water, especially for the pollution of sedimentation tanks has been paid more attention by water supply enterprises. Effects of different temperatures and illumination time on algal growth was studied. The results shows that the value of algal growth rate constant is reduced to 0.812 d⁻¹ by lowering the water temperature to 16℃, and algal growth can be further inhibited by shortening illumination time. According to the research results, the high pressure spray cooling device was installed in the sedimentation tank of the water plant for productive test and the results prove that the control rate of algae can reach 41.7% by using a high pressure spray device with the water surface temperature of 16℃ and the operation time of 20 h. The results can provide a demonstration for algal control in the sedimentation tanks of water supply plants in Shanghai and other areas.

[Abstract](253) [FullText HTML] (115) [PDF 949KB](99)

Design and Optimization of Aerodynamics Parts on a FSAE Vehicle

LI Jiayin, LIU Ningning, SHEN Yuhao, TAN Bowen, CHEN Huan, XUE Yuqing, HUANG Bixiong

2021, 35(1): 53-60.

Abstract:
Aerodynamics, as a significant field of racing car, largely affects all aspects of racing performance.The aerodynamics properties of the new season was redesigned on the premise of meeting the rules of Formula Student China (FSC) in season 2019. By using numerical progressive methods and control variate method to optimize, and carrying computational fluid dynamics (CFD) to simulate, a set of aerodynamics parts with outstanding performance was designed and completed. The results show that compared to the season 2018, the new design not only increases the downforce and lift-to-drag ratio of the racing car respectively by 81% and 91%, but also greatly improves its kinetic performance.

[Abstract](219) [FullText HTML] (725) [PDF 1194KB](163)

Forecast of Air Routes Market Share Based on Long Short-Term Memory Network

DENG Qin, DUAN Peng, QIU Wenhui

2021, 35(1): 61-66, 74.

Abstract:
The mainstream forecast method of air route market share is quality of service index (QSI) model currently, but this method needs model linearization and a lot of manual experience. An airline market share forecasting model based on long short-term memory network was proposed. The model was used to forecast the flight market share, and the validity of the model was verified by experiments on simplified data sets. Taking root mean square error as the evaluation index, the parameters of the model were optimized, and the prediction accuracy of the three methods, such as capacity prediction, QSI model and the proposed prediction model, was tested respectively. Experimental results show that the proposed model can better predict the market share of airlines, and the root mean square error is about 0.1.

[Abstract](195) [FullText HTML] (187) [PDF 777KB](92)

Reliability Research of Distribution Network with DG Based on Load Superiority Degree

LIU Xiaokang, ZHAGN Jing, LIU Chuanxiu, SONG Ziyang

2021, 35(1): 67-74.

Abstract:
In order to solve the problem that load weighting is arbitrary and the way of weighting is too single in the process of load reduction when the existing distribution network with distributed generation (DG) is operating in the island mode, a new weight weighting algorithm based on hierarchical entropy method was proposed. Firstly, the index system of load importance degree was established. Secondly, each index in the load was given subjective weight based on the analytic hierarchy process. Then, the entropy weight method was used to give objective weight to each index. On the one hand, the algorithm fully mines the objective information of the indicators, and on the other hand, it improves the diversity and synthesis of the weighting approaches.The correctness of the proposed algorithm was verified by an example evaluation of the reliability of the distribution network, which shows that the proposed algorithm has certain theoretical and practical value.

[Abstract](200) [FullText HTML] (110) [PDF 876KB](72)

Design of Control System Based on Dual Robot Grinding Platform

HAN Jiabu, CUI Guohua, SHI Ran, ZHOU Zhen

2021, 35(1): 75-81.

Abstract:
According to structural characteristics of wheel hub, the strategy of “classification and division” was adopted to formulate the grinding plan for different areas of the wheel hub. Focusing on the end face area of the hub hole with limited grinding space and complex grinding trajectory, a plan based on dual-robot collaborative grinding was proposed, and detailed design and introduction of the dual-robot collaborative control system were conducted. The design and development of the dual-robot control system were completed by the method of model-based design, and the robot grinding trajectory tracking and the wheel constant-force grinding experiment were carried out. The experimental results show that a dSPACE controller can realize the control of the dual robots, complete the grinding trajectory tracking and the grinding contact force error is within ±5 N, which will meet the needs of wheel grinding.

[Abstract](397) [FullText HTML] (160) [PDF 1398KB](98)

Finite Element Analysis of Dynamic Behavior of Microbubble with Different Wall Shapes

LIU Wenyi, HU Jiwen, ZHAO Dandan

2021, 35(1): 82-87.

Abstract:
In order to study the difference in dynamic behavior of microbubble near rigid plane, convex and concave surfaces, a finite element model of three kinds of microbubble near rigid walls under ultrasonic excitation was established. Results show that the microbubble deformation near the rigid concave surface is more obvious, and it is easy to cause transient cavitation and rupture. At the same time, the microbubble has a dynamic behavior that was deviating from the initial position and oscillating toward the wall. When the acoustic parameters and the distance from the bottom of the wall are equal, the center of gravity of the microbubble under the nearly rigid concave surface oscillates more violently, and the deviation from the initial position is the largest. The pressure on the concave surface is relatively large, the pressure on the convex surface is relatively small, and the pressure on the wall surface is positively correlated with the incident sound pressure, and the deviation between the pressure on the plane and the center of gravity of the nearby microbubble is between the convex and concave surfaces. The proposed model can provide a theoretical reference for targeted drug therapy and other aspects.

[Abstract](142) [FullText HTML] (161) [PDF 1194KB](61)

Application of Gray Metabolism GM (1,1) Model on Prediction of Minimum Wage Standard in Shanghai

ZHANG Li

2021, 35(1): 88-93, 96.

Abstract:
The establishment of the minimum wage system is an important social institution for building harmonious labor relations in China. It is of great significance to carry out minimum wage prediction. Taking Shanghai as an example, the conventional GM(1,1) model and gray metabolism GM(1,1) model were established to predict the minimum wage standard of Shanghai in the short term based on the gray system theory and method. The prediction result is in line with the Shanghai government’s goal of smoothly adjusting the minimum wage standard. Through the fitting and forecasting of the minimum wage standard in Shanghai, it can provide a scientific and reasonable basis for the government and enterprises to make relevant decisions, which has great theoretical and practical significance.

[Abstract](158) [FullText HTML] (160) [PDF 836KB](66)

Application of Function Convexity in Proving Divergence of Series

LIANG Yikong

2021, 35(1): 94-96.

Abstract:
For the convergence and divergence of series, based on the definition of convergence and divergence of series, combined with the convexity of general term functions, the sufficient conditions for the divergence of series were given when functions were upper convex or lower convex, and an example was given for application.

[Abstract](186) [FullText HTML] (193) [PDF 505KB](77)

2021 Vol. 35, No. 1