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1

Design of brake force distribution model for front-and-rear-motor-drive electric vehicle based on radial basis function

Sun B., Zhang T., Gao S., Ge W., Li B.

Archives of Transport

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2018

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Vol. 48, iss. 4

87--98

EN

To achieve high-efficiency and stable brake of a front-and-rear-motor-drive electric vehicle (FRMDEV) with parallel cooperative braking system, a multi-objective optimal model for brake force distribution is created based on radial basis function (RBF). First of all, the key factors, which are the coefficient of brake force distribution between the front and rear shafts, the coefficient of brake force distribution at wheels, the coefficient of regenerative brake force distribution between front and rear axles, that influence the brake stability and energy recovery of the FRMDEV are analyzed, the fitness functions of brake stability and energy recovery are established. Secondly, the maximum allowed regenerative brake torque influenced by the state of charge of battery is confirmed, the correction model of the optimal distribution coefficient of regenerative brake force is created according to motor temperatures. Thirdly, based on HALTON sequence method, a two-factor database, vehicle velocity and brake strength, that characterizes vehicle operation is designed. Then an off-line response database of the optimal brake force distribution is established with the use of particle swarm optimization (PSO). Furthermore, based on hybrid RBF, the function model of the factor database and the response database is established, and the accuracy of the model is analyzed. Specially, the correlation coefficient is 0.995 and the predictive error variance is within the range between 0.000155 and 0.00018. The both indicate that the multi-objective distribution model has high accuracy. Finally, a hardware-in-loop test platform is designed to verify the multi-objective optimal brake force distribution model. Test results show that the real-time performance of the model can meet the demand of engineering application. Meanwhile, it can achieve both the brake stability and energy recovery. In comparison with the original brake force distribution model based on the rule algorithm, the optimized one proposed in this paper is able to improve the energy, recovered into battery, by 14.75%.

2

Phytoplankton pigments and functional community structure in relation to environmental factors in the Pearl River Estuary

Chai C., Jiang T., Cen J., Ge W., Lu S.

Oceanologia

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2016

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No. 58 (3)

201--211

EN

Two cruises were undertaken in the Pearl River Estuary in November 2011 and March 2012 to analyze the distribution of phytoplankton pigments and to define the relationships of pigment indices and functional community structure with environmental factors. Among 22 pigments, 17 were detected by high-performance liquid chromatography. Chlorophyll a was found in all samples, with a maximum of 7.712 μg L-1 in spring. Fucoxanthin was the most abundant accessory pigment, with mean concentrations of 2.914 μg L-1 and 0.207 μg L-1 in spring and autumn, respectively. Chlorophyll a, chlorophyll c2, fucoxanthin, diadinoxanthin, and diatoxanthin were high in the northern or northwest estuary in spring and in the middle-eastern and northeast estuary in autumn. Chlorophyll b, chlorophyll c3, prasinoxanthin, and peridinin were similarly distributed during the two cruises. Chlorophyll a and fucoxanthin positively correlated with nutrients in spring, whereas 19′-hex-fucoxanthin and 19′-but-fucoxanthin negatively correlated. The biomass proportion of microphytoplankton (BPm) was higher in spring, whereas that of picophytoplankton (BPp) was higher in autumn. BPm in spring was high in areas with salinity <30, but BPp and the biomass proportion of nanophytoplankton (BPn) were high in areas with salinity >30. BPm increased but BPn reduced with the increase in nutrient contents. By comparison, BPp reduced with the increase in nutrient contents in spring, but no relationship was found between BPp and nutrient contents in autumn. The ratios of photosynthetic carotenoids to photoprotective carotenoids in the southern estuary approached unity linear relationship in spring and were under the unity line in autumn.

3

Bioaccumulation of PBDE congener 2,2',4,4'-tetrabromodiphenyl ether by Heterosigma akashiwo in response to different nutrient concentrations

Ge W., Yin X., Chai C., Zhang J.

Oceanological and Hydrobiological Studies

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2013

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Vol. 42, No. 2

139-148

EN

Changes in the bioaccumulation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in the marine alga Heterosigma akashiwo (Raphidophyceae) were examined for different concentrations of nitrate (0, 128, and 512 μmol dm-3) and phosphate (0, 8, and 32 μmol dm-3) in the semi-continuous culture with 20% renewal rate. The BDE-47 content per cell and per culture, as well as the accumulated percentage of available BDE-47, presented a significant decreasing trend with the increase in nitrate and phosphate concentrations. The N-0 (4.0 × 10^-6 ng cell-1) and P-0 (5.8 × 10^-6 ng cell-1) treatments had significantly higher BDE-47 content per cell than other treatments. In comparison, the difference in BDE-47 per algal culture and accumulated percentage between the nitrate treatments or phosphate treatments was not as obvious as the BDE-47 content per cell. BDE-47 per cell presented significantly negative correlation with nitrate and phosphate concentrations, and the accumulated BDE-47 was in positive correlation with lipid content. log BAFlip for BDE-47 in H. akashiwo ranged from 6.70 to 7.25. The results of this study indicate that variation in BDE-47 accumulation by H. akashiwo corresponds to the change in cellular lipid content induced by different nitrate and phosphate concentrations.

4

Positive solutions for discrete boundary value problems with p-Laplacian

Ji D., Ge W.

Journal of Applied Analysis

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2010

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Vol. 16, nr 1

107-119

EN

In the paper, we obtain the existence of positive solutions and establish a corresponding iterative scheme for the following two-point discrete boundary value problem with p-Laplacian: Δ(∅p(Δu(k - 1))) + e(k)f(u(k)) = 0 , k∈ N(1,T) , u(0) - B0 (Δu(0)) = 0 , u(T + 1) + B1 (Δu(T)) = 0. The main tool is the monotone iterative technique.

5

Positive solutions for a class of nonresonant m-point boundary value problems

Feng M., Zhang X., Ge W.

Journal of Applied Analysis

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2008

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Vol. 14, nr 1

115-129

EN

This paper concerns the existence and multiplicite of positive solutions for a class of nonresonant m-point boundary-value problem of second-order diferential equations Lx = λw(t)(t, x), 0ρ -integrable for some 1≤ p ≤ +∞. the arguments are based upen fixed point theorems in a cone and Hoelder's inequqlity. The nonexistence of positive solution is also studied. In addistion, some examples are included to demonstrate the main results.

6

Existence of solutions for nonlocal boundary value problem with singularity in phase variables

Tian Y., Ge W.

Journal of Applied Analysis

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2006

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Vol. 12, nr 1

93-107

EN

In this paper, we prove existence results for singular problem [wzór]. Here the positive Carathédory function ∫ may be singular at the zero value of all its phase variables. Proofs are based on the Leray-Schauder degree and Vitali's convergence theorem.

7

Further results on oscillation of hyperbolic differential equations of neutral type

Wang M., Wang P. G., Ge W.

Journal of Applied Analysis

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2004

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Vol. 10, nr 1

117-129

EN

In this paper, we investigate a class of hyperbolic differential equations of neutral type [wzór] (E) and obtain some new sufficient conditions of the oscillation for such equations satisfying boundary condition [wzór] (B)