Volume 43,Issue 10,2020 Table of Contents

1 Optimization of PHEV energy management strategy considering battery life and energy consumption economy

QIN Datong , ZHANG Xiaoxing , YAO Mingyao

2020, 43(10):1-11. DOI: 10.11835/j.issn.1000-582X.2020.10.001

[Abstract](687) [HTML](896) [PDF 1.30 M](1243)

Abstract:
In this paper, a vehicle dynamics model and a battery life attenuation model were established for a hybrid dual-motor plug-in hybrid vehicle. At the same time, to reflect the influence of battery temperature on battery life, a battery temperature model was also established. Considering the impact of energy management control on energy economy and battery life decay, a energy management strategy of multi-mode logic rules was developed, and the impact of different control parameters on energy economy and battery life was analyzed. A multi-objective optimization model with equivalent fuel consumption and battery life attenuation was established to optimize the energy management strategy control parameters based on multi-objective improved genetic algorithm. The results show that the Pareto optimal solutions based on the design and optimization method of PHEV (plug-in hybrid electric vehicle) energy management strategy in this article are feasible in terms of both energy consumption economy and battery life of plug-in hybrid vehicles. With many different optimal solutions of control parameters, it provides a variety of alternative schemes for the design and application of PHEV energy management strategy.

2 Application of producer/consumer mode to shearing machine detection system

ZHOU Yangting , WANG Shilong , ZHOU Jie , YANG Bo

2020, 43(10):12-19. DOI: 10.11835/j.issn.1000-582X.2020.10.108

[Abstract](394) [HTML](824) [PDF 5.93 M](852)

Abstract:
The existing shearing machine detection system mostly adopts the master/slave design mode, which involves many parameters to be detected, a large amount of data, and a complicated detection process, and it requires simultaneous acquisition of video signals and physical signals. Moreover, the system has data loss and video distortion, and the data collection speed becomes slower over time. To solve the above problems, a LabVIEW producer/consumer design mode improvement scheme was proposed. The physical signal and the video signal were separately collected, and the data acquisition and data analysis were respectively performed in two cycles, and the two loops were connected by means of a queue to realize an effective combination of each cycle. It has been verified by experiments that the improved design greatly improves the data acquisition and analysis speed, reduces the coupling between the signals, and is obviously effective in avoiding data loss and distortion. So it is worthy of application and promotion in various inspection systems of the mechanical, electrical, energy and other industries.

3 Maintenance strategy of wind turbine based on the delay time model

LI Xiang , ZHU Caichao , LI Yao , FAN Zhixin

2020, 43(10):20-28. DOI: 10.11835/j.issn.1000-582X.2020.10.003

[Abstract](571) [HTML](661) [PDF 1.54 M](969)

Abstract:
In order to solve the problems of high maintenance cost of wind turbines and low efficiency of operation and maintenance resulting from unreasonable maintenance strategy, a research on maintenance strategies of a series connection system of wind turbines was carried out. The component fault was devided into potential fault and function fault based on the delay-time theory and a opportunistic maintenance strategy was proposed focusing on the preventive maintenance. A delay was made in the maintenance of components in search of maintenance opportunity. An opportunistic maintenance model for wind turbines was established with considerations of the influencing factors, like spare part logistics, downtime and maintenance costs. Using the field fault data, the Monte Carlo method was adopted to solve the proposed model and the influences of different inspection durations and different deferred maintenance time on the life-cycle availability and maintenance cost of wind turbines were explored. The results show that the opportunistic maintenance strategy considering deferred maintenance is superior to traditional preventive maintenance in cost-efficiency with engineering practice. With the optimal strategy obtained by the model proposed, the availability of wind turbine can rise up to 98%.

4 Contact characteristics analysis of involute cylindrical worm and helical gear transmission

LI Shixuan , CHEN Bingkui , CHEN Yonghong

2020, 43(10):29-37. DOI: 10.11835/j.issn.1000-582X.2020.10.004

[Abstract](447) [HTML](794) [PDF 1.16 M](884)

Abstract:
Aimed at the solution of the contact problem in the involute cylindrical worm and the helical gear transmission pair, a mathematical model of conjugate tooth surface contact geometry of the involute cylindrical worm and the helical gear was established based on the gear geometry theory and the differential geometry. Taking a transmission pair equipped in a type of horizon drive machine as an example, we simulated the tooth surface contact of the worm helical gear transmission pair with numerical analysis and carried out the experiment of tooth surface contact. The analysis results show that the contact position and contact area can be effectively controlled by adjusting the transmission parameters such as transmission ratio, normal pressure angle, normal modulus and helix angle and they will have a theoretical significance for the design and manufacture of the cylindrical worm and the helical gear transmission pair.

5 Simulation and analysis of wet clutch engagement characteristics

WANG Cheng , QIN Datong , WU Bangzhi , FANG Hongsheng , CHENG Kun

2020, 43(10):38-51. DOI: 10.11835/j.issn.1000-582X.2020.110

[Abstract](531) [HTML](411) [PDF 2.84 M](1167)

Abstract:
In order to study the engagement characteristics of wet clutch, the mathematical model of wet clutch engagement process was established based on fluid lubrication theory, rough surface elastic contact theory, adsorption heat theory and heat transfer theory, with the combined effects of friction surface temperature, relative speed, roughness and load on the friction coefficient taken into consideration. The effects of engagement pressure, friction surface roughness, friction material permeability on oil film thickness, relative angular velocity and transfer torque were discussed respectively. The results show that with the increase of the engagement pressure, the torque response, the relative angular velocity reduction speed and the oil film thickness reduction speed are accelerated, but the engagement time is shortened and the minimum oil film thickness is reduced. With the reduction of the friction surface roughness, the torque response slows down, the relative angular velocity reduction speed and the oil film thickness reduction speed are accelerated, the engagement time is shortened, and the minimum oil film thickness is reduced. With the increase of the friction material permeability, the torque response, the relative angular velocity reduction speed and the oil film thickness reduction speed are accelerated, and again the engagement time is shortened, but the minimum oil film thickness barely changes.

6 Comparison and analysis of performance prediction methods for GDI turbocharged engine based on limited data

YANG Daoguang , ZHANG Li

2020, 43(10):52-61. DOI: 10.11835/j.issn.1000-582X.2020.109

[Abstract](423) [HTML](719) [PDF 798.96 K](859)

Abstract:
In order to reduce the experimental cost of establishing engine performance prediction model, machine learning algorithms with powerful non-linear problem analysis ability were employed to predict the performance of gasoline direct injection (GDI) turbocharged engine, such as general regression neural network (GRNN) and support vector regression (SVR). The Taguchi orthogonal experiment method and the Latin hypercube sampling (LHS) were introduced to determine the operation points of the training data and the test data. And then based on the training models containing the same training data of only 25 samples, the prediction performance of both GRNN and SVR was tested and compared using the same 100 sets of testing data. The comparative analysis shows that GRNN has the risk of converging to the local minimum when the experimental data is limited, whereas SVR can find the optimal global solution with good prediction accuracy and generalization ability. So SVR is very suitable for GDI turbocharged engine performance predictions and significantly reduces experimental costs.

7 Modeling and simulation of 3D stochastic pavement based on inverse Fourier transform

YU Gui , ZHOU Xinglin , DONG Juming , DONG Zejiao

2020, 43(10):62-69. DOI: 10.11835/j.issn.1000-582X.2020.107

[Abstract](545) [HTML](994) [PDF 3.20 M](1043)

Abstract:
In order to meet the needs of virtual experiment in engineering, a 3D stochastic road roughness modeling method using power spectral density function is studied. By using the road spectrum fitting formula of power function adopted in the national standard, the analytical expression of two-dimensional power spectrum of road surface is derived, which avoids the parameter estimation problem of rational function method. The process of generating 3D stochastic pavement by two-dimensional inverse Fourier transform is established, and the E-grade pavement in the national standard is simulated by the performance requirements of a certain automobile vibration system. The power spectrum of the simulated pavement is estimated by using periodogram method and AR parameter model method respectively. The estimated results show that the simulated pavement spectrum is highly consistent with the standard pavement spectrum. The method based on two-dimensional inverse discrete Fourier transform is not only accurate and fast, but also has strong practicability.

8 Application of PMM fiber hinges to the value of stiffness reduction coefficient of bent structure

LIU Yi , LIU Xuan , LI Bo

2020, 43(10):70-78. DOI: 10.11835/j.issn.1000-582X.2020.10.008

[Abstract](411) [HTML](503) [PDF 2.40 M](779)

Abstract:
At present, most of the design of reinforced concrete bent structures is based on elastic assumption. However, in practical engineering, the stress of bent structure is often accompanied by the cracking of concrete and the bond slip between reinforcement and concrete, etc. The second-order effect of the bent structure often aggravates the structural stiffness degradation. Therefore, it is necessary to calculate the second-order effect of material nonlinearity in the analysis of bent structure. A practical method in engineering design is to introduce the elastic second-order analysis with stiffness reduction considered, and its accuracy depends largely on the value of the stiffness reduction factor. This paper tries to find a reasonable stiffness reduction factor of the bent structure through the PMM fiber hinge based on the material model.

9 Effect of stress amplitude ratio on multiaxial fatigue crack initiation and propagation behavior of 2A12-T4 aluminum alloy

LIN Wanjia , ZHANG Jianyu , LIU Tianqi , LIU Hao

2020, 43(10):79-89. DOI: 10.11835/j.issn.1000-582X.2019.259

[Abstract](475) [HTML](450) [PDF 5.41 M](993)

Abstract:
Prediction of fatigue failure behaviors by simplified uniaxial loads are no longer applicable since many of the engineering structures are often subjected to complex multiaxial fatigue loads during service. Therefore, accurately predicting the multiaxial fatigue failure behavior of engineering structures under complex loads is of great significance for improving structural safety. Fatigue crack initiation and propagation is the most intuitive response to fatigue failure behavior. In this study, multiaxial fatigue tests under different stress amplitude ratios with fixed von Mises stress amplitude were carried out by using 2A12-T4 aluminum alloy solid round bar specimens. The surface crack initiation and propagation path of the specimen under different stress amplitude ratios were studied by observing the specimens under a metallographic microscope, and the multiaxial fatigue failure behavior of 2A12-T4 aluminum alloy under different stress ratios was discussed. Results show that many cracks initiate on the surface of all the specimens, but the main crack which causing fatigue failure was only one. The crack initiation direction is always close to the maximum shear stress amplitude plane, and the length and direction of the stage Ⅰ crack are all affected by the stress amplitude ratio. Propagation of the main crack are mainly along the maximum shear stress amplitude plane, which means the maximum shear stress amplitude is the main control parameter that causes the multiaxial fatigue failure of 2A12-T4 aluminum alloy.

10 Simulation of an emergent water pollution accident in the portion of the Yangtze River running through the main urban areas of Chongqing

LONG Tianyu , QU Yao

2020, 43(10):90-103. DOI: 10.11835/j.issn.1000-582X.2020.105

[Abstract](541) [HTML](572) [PDF 4.77 M](718)

Abstract:
Due to the special terrain of Chongqing City, various types of drainage trunks have been built along the Yangtze River and the Jialing River. Once a pipeline bursts, it will endanger the water quality of downstream water intake. Aiming at the establishment of a management system for sudden water pollution risk that may occur in the Chongqing Section of the Yangtze River after the impoundment of the Three Gorges Reservoir up to 175 m, a two-dimensional hydrodynamic water quality coupling model was built based on the measured topographic and hydrological data, and optimal inversion method was used to determine the roughness. The finite element method was applied to simulating the temporal and spatial variations of pollutant concentrations including the five-day biochemical oxygen demand (BOD₅), the chemical oxygen demand (COD), the total nitrogen (TN), and the total phosphorus (TP) under the condition that the fractured pipeline be completely repaired after 24 h or 48 h in the high and low water periods. The simulation results can provide a scientific basis for the optimization of the emergency plan in case of a sudden drain pipe rupture in Chongqing.

11 Study on adsorption property of Cr(VI) by zinc chloride modified corn stalk biochar

AN Qiang , Chorloualy Koualee , JIN Lin , LI Zheng , JIAO Yixiao , LUO Qian

2020, 43(10):104-113. DOI: 10.11835/j.issn.1000-582X.2019.264

[Abstract](593) [HTML](894) [PDF 2.75 M](843)

Abstract:
To improve the removal efficiency of chromium in the water and obtain a kind of adsorbent with low-cost and high efficiency, corn stover biochar was produced and modified by zinc chloride(ZnCl₂). The experimental results show that when the dosage of modified carbon is 2 g/L, the initial pH is 2, the initial concentration of Cr(VI) is 100 mg /L and the adsorption time is 6 h,the Cr(VI) removal rate can reach 99.3% under the optimal modifier ratio, which is 73.7% higher than that of unmodified biochar. Furthermore, the effects of single factors such as modifier ratio, solution pH, adsorption temperature and ionic strength on the adsorption performance were investigated. The adsorption kinetics and adsorption isotherms of modified carbon on Cr(VI) were also studied. The results indicate that the adsorption is a spontaneous endothermic process and the adsorption reaction is in accordance with the quasi-second-order kinetic equation and the Langmiur isothermal model. The maximum saturated adsorption capacity is 72.46 mg/g. The biochar(BC) and modified biochar(MBC) were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR) and X-ray diffraction(XRD). The analysis shows that the surface of the modified carbon is rough with obvious microporous structure, increased adsorption sites and aromatization, thereby improving the adsorption performance, and zinc is present on the surface of the biochar as hydroxide particles.

12 Characteristics analysis of ozone and its precursors in midsummer at Airport New City of Xi-Xian New Area, Shaanxi Province, China

LIANG Junning , WANG Hao , RUI Shoujuan , LIU Jie , WANG Ping

2020, 43(10):114-120. DOI: 10.11835/j.issn.1000-582X.2019.267

[Abstract](547) [HTML](688) [PDF 1.23 M](716)

Abstract:
This paper is aimed at studying of high concentration ozone events in summer in Airport New City (ANC) of Xi-Xian New Area, Shaanxi Province. Online instruments were used to continuously monitor the hourly concentration of ozone and its precursor (nitrogen oxides (NO_x) and volatile organic compounds (VOCs)) in ANC from 27 July to 26 August 2018(31 days). The results show that the ozone concentration is generally high during the midsummer (July & August) at ANC, and the average concentration is 103.8 μg/m³ and the maximum concentration reaches 306 μg/m³. There are 16 days when the ozone concentration exceeds the limit during the study period and its diurnal variation of concentration shows a single peak trend, with the maximum value about 17:00 p.m. and the minimum value around 6:00 a.m. The correlation coefficient between ozone and NO_x is -0.648 7, and that between ozone and VOCs is -0.091 1. When VOCs/NO_x is below 6.43, VOCs play a leading role in the generation of ozone, and when VOCs/NO_x is above 6.43, NO_x plays a decisive role in the generation of ozone.

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