Volume 40,Issue 12,2017 Table of Contents

1 Multi-objective topology optimization for vehicle steering knuckle based on the compromise programming method

XU Zhongming , TAO Nengfa , LAI Shiyang , LIANG Tao , XIA Xiaojun

2017, 40(12):1-7. DOI: 10.11835/j.issn.1000-582X.2017.12.001

[Abstract](1087) [HTML](398) [PDF 1.55 M](1541)

Abstract:
Steering knuckle has a direct influence on the vehicle's operating stability and driving safety. In order to meet the requirements of lightweight of steering knuckle and automobile dynamics simultaneously, interpolation model of SIMP(solid isotropic material with punishment) density function and weighted compromise optimization method are applied to define synthesis objective function and carry out multi-objective topology optimization of a solar car's steering knuckle. The purpose of the optimization is to make the first order vibration frequency and the stiffness of the static working condition reach the comprehensive optimum value. After optimization, the first order vibration frequency of the steering knuckle is increased by 76.87%, the stiffness under the static working condition is increased by 90.25%, the mass is reduced by 44.47%, and the effect of lightweight is remarkable.

2 Design and dynamic characteristic analysis of multi-axis precision transmission test platform

WEI Bo , CHEN Yonghong , LIANG Dong , CHEN Bingkui

2017, 40(12):8-15,34. DOI: 10.11835/j.issn.1000-582X.2017.12.002

[Abstract](875) [HTML](426) [PDF 1.44 M](1514)

Abstract:
The dynamic characteristic of transmission test platform has a major impact on the accuracy and reliability of test results for precision reducers. A self-developed multi-axis precision transmission test platform is taken as the research object, and a calculating method of the joint part stiffness of cross roller linear guide way is proposed based on Hertz Contact theory. According to the actual test working state of cross axis reducer, spring unit is applied to simulate the contact characteristic of guide way joint part and the dynamic model of test platform at limit position is established. And then, the theoretical modal analysis is carried out by finite element method and the natural frequencies of the first 4 steps and modal shapes of the platform are obtained. Finally, the dynamic characteristic of test platform is verified by sample testing. The maximum vibration velocity of platform under actual working state is 0.478 mm/s. The results show that this new transmission test platform has excellent dynamic performance and it can satisfy the vibration criterion of precision equipments.

3 Field-circuit coupled analysis on in-wheel motor of electric vehicle

ZHANG Heshan , DENG Zhaoxiang , ZHANG Yu , TUO Jiying , YANG Jinge

2017, 40(12):16-23. DOI: 10.11835/j.issn.1000-582X.2017.12.003

[Abstract](1263) [HTML](293) [PDF 3.03 M](1163)

Abstract:
Aiming at the fact that the circuit simulation and electromagnetic analysis method is difficult to accurately take into account the magnetic material permeability nonlinearity, and the finite element method is difficult to analyze the external circuit with non-standard sine excitation, we use the field-circuit coupling method to analyze the efficiency of in-wheel motor for electric vehicle, solve the electromagnetic field finite element equation and the external circuit equation together, and consider the influence of nonlinear factors such as time harmonic current on the magnetic field, to realize the direct coupling of the electromagnetic field quantity and the electrical quantity. The coupling equations of the electromagnetic field and the external circuit of the in-wheel motor, the equation of motion and the power loss are derived, and the load induced electromotive force and power loss are calculated, the difference between the finite element method and the field-circuit coupling method is compared, then the distribution of power loss density is studied. The efficiency characteristics of the motor under different working conditions are calculated by finite element method and the field-circuit coupling method respectively, and the results show that the field-circuit coupling method is more accurate and the correctness of the analysis method is proved.

4 Yaw stability control of wheel-drive electric vehicle

LI Yinong , HU Yiming , ZOU Tao

2017, 40(12):24-34. DOI: 10.11835/j.issn.1000-582X.2017.12.004

[Abstract](1082) [HTML](492) [PDF 3.03 M](1753)

Abstract:
A stability control system based on direct yaw moment control is proposed to improve the stability of wheel-drive electric vehicles. For the chattering problem of sliding mode controller, a stability controller based on fuzzy sliding mode control is established first. And then, as the sideslip angle is difficult to measure, a nonlinear sliding mode observer with simple structure and fast calculation is designed. Considering the online simulation time and practical constraints, an equal proportion allocation controller is proposed to distribute the driving/braking torque on each wheel. At last the performance of the designed integrated controller is demonstrated through the co-simulation of MATLAB/Simulink and Carsim. The result reveals that the controller can improve the stability of vehicle effectively with smoother control output.

5 A computing approach of information system vulnerability's exploited probability

CHAI Jiwen , WANG Sheng , LIANG Huihui , HU Bing , XIANG Hong

2017, 40(12):35-42. DOI: 10.11835/j.issn.1000-582X.2017.12.005

[Abstract](898) [HTML](662) [PDF 1.24 M](1342)

Abstract:
The evaluation results are impacted by many subjective factors since the existing risk assessment for information systems does not take the correlation of vulnerabilities into account. By combining two assessment vectors, i.e. access complexity and chosen probability, we transfer the so called "accessed complexity" evaluation method into an "exploited probability" evaluation approach, and use Bayesian networks' forward inference to accumulation each of vulnerability's chosen probability. Theoretical and experimental analysis show that the proposed "exploited probability" evaluation method is more accurate and reasonable than associated existing research work.

6 Promoting effects of CaF₂ on the aggregation and growth of metal phases in self-reduction of laterite nickel ore

XUE Zhengliang , XIAO Chengpeng , HANG Guihua , XIONG Tianyu , XIE Yucheng

2017, 40(12):43-51. DOI: 10.11835/j.issn.1000-582X.2017.12.006

[Abstract](821) [HTML](465) [PDF 2.85 M](1179)

Abstract:
In view of low-grade laterite nickel ore including high magnesium and silicon, the process of coal-based self-reduction, grinding and magnetic separation is utilized to produce ferronickel powders. The effects of C/O atomic ratio on the self-reduction of iron oxides and nickel oxides are investigated, as well as the influences of CaF₂ on the reduction of oxides and the precipitation, aggregation and growth of metal phases in the self-reduction. The results show that under the action of CaF₂, the reduction of iron oxides can be suppressed by reducing the C/O atomic ratio to obtain ferronickel powders in high-grade nickel but the recovery rate of nickel will be decreased. The low melting point tremolite(Ca₂Mg₅(Si₄O₁₁)₂F₂) is generated from the solid-state reaction between CaF₂ and silicate gangue with high melting point, which can make the silicate minerals transform from island structure to chain structure, increase the reactivity of silicate minerals and then promote the reduction of nickel oxides and iron oxides. With the addition of CaF₂, the melting temperature of laterite nickel ore gangue can be decreased. In that case, the precipitation, aggregation and growth of metal phases can be strengthened in self-reduction and then the separation of metal and gangue can be promoted. Accordingly, the grade of nickel and iron in ferronickel powders and the recovery rate of metal elements are improved significantly.

7 Fault characteristic gas analysis of breakdown discharge of vegetable insulating oil

CAI Shengwei , WANG Feipeng , CHEN Cheng , FAN Fan , CHEN Jiangbo , WEN Gang , LI Jian , XIANG Chenmeng , WANG Ji

2017, 40(12):52-58. DOI: 10.11835/j.issn.1000-582X.2017.12.007

[Abstract](877) [HTML](363) [PDF 1.26 M](1103)

Abstract:
The electrical breakdown of camellia seed vegetable insulating oil and mineral insulating oil transformer is simulated in experiments, respectively. The dissolved gas characteristics of two kinds of insulating oil are studied by means of dissolved gas analysis method. The type and percentage of gas produced by oil paper breakdown of the two kinds of insulating oil are analyzed and compared. Results show that the two insulating oils produce seven characteristic gases, i.e. H₂, CH₄, C₂H₄, C₂H₆, C₂H₂, CO and CO₂, under the typical electrical faults. The total amount of gas produced in camellia-seed vegetable insulating oil increases with the increase of the times of breakdown, and the content of CO and CO₂ produced by the insulating oil of camellia seed vegetable is greater than that of mineral insulating oil. The percentage of C₂H₂ is always the highest, which shows that C₂H₂ is the main characteristic gas of camellia-seed vegetable insulating oil breakdown.

8 Preparation of high purity iron by industrial pure iron electrolysis

HUANG Hongbing , PENG Qichun , QIU Wentao

2017, 40(12):59-70. DOI: 10.11835/j.issn.1000-582X.2017.12.008

[Abstract](1163) [HTML](482) [PDF 1.64 M](2401)

Abstract:
Pure iron is used as raw material to analyze the influencing factors of electrolytic iron through orthogonal design. Electro-deposition rate, current efficiency, purity and appearance of the electrolytic iron are taken as the indexes to find out the conspicuousness of each factor and their optimal combination scheme. The purity of electrolytic iron and its main impurities are analyzed by ICP-AES and SEM, and the impurity oxygen is also analyzed and purified through annealing reduction. Besides, the electrolytic iron is separated by using NaOH solution, and the concentration of SO₄^2-is analyzed through ICP-AES. The results show the best combination of electrolysis iron test program is that the concentration of Fe²⁺solution is 50 g/L, the pH value is 4, the temperature is 25℃ as well as the current density is 100 A/m². Under the optimal conditions, the electro-deposition rate is 0.549 g/h, the current efficiency is 89.2%, and the purity of electrolytic iron is over 99.98%. After annealing, oxygen content is greatly reduced and the amount of sulfate in the leachate is about 30 mg/L. From actual electrolysis conditions, it can be found that the main forms of oxygen and sulfur are iron oxides and ferrous sulfate.

9 A review and technical analysis about membrane distillation for desalination

ZHENG Taojie , CHEN Zhili , YANG Yi

2017, 40(12):71-78. DOI: 10.11835/j.issn.1000-582X.2017.12.009

[Abstract](958) [HTML](1752) [PDF 901.98 K](1860)

Abstract:
The principle of membrane distillation and the factors related to membrane permeation flux are introduced, the advantages and disadvantages of membrane distillation in seawater desalination are summarized in detail and the classification of membrane distillation are introduced. Problems related to membrane fouling and development of membrane materials in distillation are analyzed and the development tendency of the membrane distillation technology is prospected.

10 Elimination of persulfate interference in determination of COD in organic wastewater

ZENG Xiaolan , HUANG Yongzhou , ZHANG Yu , LUO Wanshen , LI Zhong , DING Wenchuan

2017, 40(12):79-86. DOI: 10.11835/j.issn.1000-582X.2017.12.010

[Abstract](1104) [HTML](1017) [PDF 1.21 M](1883)

Abstract:
As a new advanced oxidation technology, advanced oxidation process of persulfate has been widely used in wastewater treatment and chemical oxygen demand(COD)is usually taken as an important indicator to identify the characteristics of organic wastewater. When COD is determined by potassium dichromate method, the residual persulfate in organic wastewater has interference with the measurement results. Therefore, the interference mechanism is investigated and the elimination measures of the interference are proposed. The results reveal that COD_Cr testing values are higher than the actual values for the reducibility of residual sulfate (S₂O₈^2-). The interference degree varies with the concentrations of S₂O₈^2- in the wastewater. The relationship between concentration of S₂O₈^2-and COD_Cr is obviously linear in both high and low COD_Cr concentration measuring range. For COD_Crranging from 0 to 150 mg/L and COD_Crranging from 0 to 1 500 mg/L, the linear relationship and the contributions of COD_Cr concentration variation by 1g S₂O₈^2- are y=36.120 2x+0.571 1(R²=0.997 9), 36.120 2 mg and y=45.171 6x+38.031 6(R²=0.998 4), 45.171 6 mg respectively. In COD_Cr standard solution system and the actual wastewater system, the percentage of △COD_Cr1 (contribution value of COD_Cr by S₂O₈^2-) and △COD_Cr2 (the difference between COD_Cr measured value and raw wastewater actual value) is less than 10% of the actual COD_Crin raw wastewater. The actual COD_Cr value of water sample could be accurately calculated by deducting △COD_Cr1 based on the linear equation which could effectively eliminate the interference caused by residual S₂O₈^2- in COD_Cr determination.

11 Improved ESN neural network model for mine water inrush identification

LI Yuanzhi , NIU Guoqing , ZHANG Xuanxuan

2017, 40(12):87-96. DOI: 10.11835/j.issn.1000-582X.2017.12.011

[Abstract](900) [HTML](464) [PDF 1.10 M](1008)

Abstract:
It is difficult to judge the type of water source with similar water chemistry characteristics by the traditional water prediction model. The similarity analysis of 26 typical water samples is carried out by using water chemical composition analysis and FCM (fuzzy C-means)cluster analysis method. Four samples with higher similarity are extracted as samples to be tested and loaded into the GA_ESN discriminant model based on damped least squares regularization method, and the GA_ESN discriminant model of the regularization method is compared with the improved GA_BP and the standard GA_ESN model. The results show that the improved GA_BP discriminant model has the worst effect and the prediction accuracy is only 50%. The back estimation rates and prediction accuracy of the standard GA_ESN model are 100%, however, the accuracy of the model requires a high degree of complexity of the model, and it's prone to have overfitting problem. And the improved GA_ESN discriminant model can make up for the shortage of the above model, which can not only simplify the model training process, but also improve the accuracy of water source identification. Therefore, the model can be used as a fast and effective method to identify the source of mine water inrush.

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