Efficiency Analysis of Port Companies in China Using DEA and the Malmquist Method

He, Wenjun,Ma, Hye-Min,Yeo, Gi-Tae Korean Institute of Navigation and Port Research 2017 한국항해항만학회지 Vol.41 No.5

The efficiency of port operations is an important indicator of port development. Moreover, there is excess handling capacity in Chinese ports, which results in a slower speed of development. Under the detrimental environment of the international shipping market, it is necessary to improve the operation efficiency of ports for long-term development. This paper provides an assessment of the competitiveness of Chinese seaport companies using the Boston Consulting Group's matrix, and efficiency measurements using a data envelopment analysis and the Malmquist method. This analysis showed that highly efficient companies reformed their development strategies, which should be a solution considered by less efficient companies, such as Shenzhen Yan Tian Port Holdings Co., Ltd.. Although, having high throughput should be reformed in the investment structure. This research will assist port companies in gaining effective operating experience, and governments in establishing strategic planning to enhance the efficiency of port development.

Efficiency Analysis of Port Companies in China Using DEA and the Malmquist Method

Wenjun He,Hye-Min Ma,Gi-Tae Yeo 한국항해항만학회 2017 한국항해항만학회지 Vol.41 No.5

The efficiency of port operations is an important indicator of port development. Moreover, there is excess handling capacity in Chinese ports, which results in a slower speed of development. Under the detrimental environment of the international shipping market, it is necessary to improve the operation efficiency of ports for long-term development. This paper provides an assessment of the competitiveness of Chinese seaport companies using the Boston Consulting Group’s matrix, and efficiency measurements using a data envelopment analysis and the Malmquist method. This analysis showed that highly efficient companies reformed their development strategies, which should be a solution considered by less efficient companies, such as Shenzhen Yan Tian Port Holdings Co., Ltd.. Although, having high throughput should be reformed in the investment structure. This research will assist port companies in gaining effective operating experience, and governments in establishing strategic planning to enhance the efficiency of port development.

Creepage Distance Measurement Using Binocular Stereo Vision on Hot-line for High Voltage Insulator

Wenjun He,Jiake Wang,Yuegang Fu 한국광학회 2018 Current Optics and Photonics Vol.2 No.4

How to measure the creepage distance of an insulator quickly and accurately is a problem for the power industry at present, and the noticeable concern is that the high voltage insulation equipment cannot be measured online in the charged state. In view of this situation, we develop an on-line measurement system of creepage distance for high voltage insulators based on binocular stereo vision. We have proposed a method of generating linear structured light using a conical off-axis mirror. The feasibility and effect of two ways to solve the interference problem of strong sunlight have been discussed, one way is to use bandpass filters to enhance the contrast ratio of linear structured light in the images, and the other way is to process the images with adaptive threshold segmentation and feature point extraction. After the system is calibrated, we tested the measurement error of the on-line measurement system with a composite insulator sample. Experimental results show that the maximum relative error is 1.45% and the average relative error is 0.69%, which satisfies the task requirement of not more than 5% of the maximum relative error.

Research on Temperature Rise Characteristics of Vehicle Motors Under Bench Working Condition

He Liange,Shi Wenjun,Xia Xiaohua,Wu Xinyang,Chen Hongling,Yan Xin 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

The specifi c bench test specifi ed by the product design standard is an important basis for judging whether the vehicle motor meets the requirements. To study the temperature rise characteristics of automotive permanent magnet synchronous motors under bench test conditions. Firstly, the bench condition was taken as the target we need to study, and the fi nite element method was used to calculate the loss of each part during the bench test condition. Secondly, use this loss as the heat source for temperature fi eld calculation to simulate the temperature fi eld of the motor under bench test conditions. Finally, a bench test platform was built for testing, and the test results and simulation results were compared and analyzed. Studies have shown that in the entire process of changing conditions, the temperature of each component is not the same as the sensitivity to changes in operating conditions. The maximum relative error between simulation and experiment was 9.4%, which verifi es the eff ectiveness of this research method and process, which has certain guiding signifi cance for the design and optimization of vehicle motors.

Boiling heat transfer-based temperature rise characteristics of automotive permanent magnet synchronous motors at peak operating conditions

He Liange,Chen Hongling,Shi Wenjun 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

Using two-phase flow boiling heat transfer theory, the RPI subcooling boiling heat transfer model was established to study the temperature rise characteristics of the permanent magnet synchronous motor (PMSM) of electric vehicles under peak operating conditions, and the effects of coolant inlet temperature, altitude and inlet flow rate on the motor temperature rise were analyzed. The results showed that: the temperature rise characteristics of the motor are closer to the test results when boiling heat transfer is considered after the motor is warmed up, so the effect of boiling heat transfer of the cooling system should be considered when studying the temperature rise characteristics of the motor; The temperature rise characteristic of the motor increases with the increase of coolant inlet temperature at peak working condition. The short time required for the motor winding to reach 150 °C indicates that the motor temperature rises quickly. In the plateau environment, the temperature growth rate of the motor at peak working conditions increases with the increase of cooling water inlet temperature, while the motor temperature decreases with the decrease of atmospheric pressure. Thus, due to the boiling heat transfer phenomenon of cooling water two-phase flow, the temperature rise characteristic of the motor at high altitude is better than that in plain area.

Loss Prediction of Vehicle Permanent Magnet Synchronous Motor Based on Deep Learning

He Liange,Wu Xinyang,Nie Yuanhang,Shi Wenjun 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

Based on the deep learning BP neural network algorithm, we establish the electromagnetic torque and loss prediction analysis model of permanent magnet synchronous motor to provide new design ideas and methods for optimizing motor structure design. In this paper, four-rotor structure parameters which are Rib, Air Gap, Magnet Thickness and Magnet Width, motor electromagnetic torque, and motor losses of the “V” type Interior Permanent Magnet Synchronous Motor are selected as the research object. The BP neural network structure prediction model with 2 visible layers and 2 hidden layers was built by 256 groups of sample data calculated by Maxwell transient electromagnetic simulation. 226 out of 256 randomly selected data samples were used to train the prediction model, and 30 groups were used to test the accuracy and generalization ability of the prediction model. and the prediction results data were compared with the deep learning prediction model through finite element simulation data. The results show that the BP neural network small-sample data prediction model has high prediction accuracy in the loss prediction of the vehicle permanent magnet synchronous motor, and verifies the feasibility of the motor torque and loss prediction model based on the deep learning algorithm.

A study on the liquid length and flame lift-off length for Hydrogenated Catalytic Biodiesel/Diesel blended fuel in a constant volume combustion chamber

( Zhixia He ),( Weiwei Shang ),( Qian Wang ),( Xianyin Leng ),( Wenjun Zhong ),( Jiawei Cao ),( Bei Li ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

The spray and combustion process is the fundamental factors affecting performance and emission of diesel engine, while the physicochemical properties of the fuel directly determine the spray combustion characteristics. The renewable and clean alternative fuel, which showed great potential of energy saving and emission reduction, makes studying on the influence of fuel physicochemical properties on the spray combustion characteristics very essential. In this paper, the effects of fuel physical and chemical properties on the spray combustion characteristics of diesel engine were studied by using mixed fuel with the catalytic hydrogenation biodiesel and diesel in constant volume combustion chamber. The effects of fuel physicochemical properties on the liquid length (LL) under combustion and evaporation conditions were studied based on the laser Mie scattering technic. The results showed that the LL under combustion conditions is shorter than the LL under evaporation conditions, and the difference became little when the ambient density is higher. In addition, the LL under combustion conditions decreases with the increase of fuel density and ambient temperature, while the ambient oxygen concentration and injection pressure have little effect on the LL. By using laser Mie scattering technology and chemical fluorescence visualization method innovatively, the LL under combustion and lift-off flame (LOL) was studied simultaneously, studying the interaction between them showed that the combustion LL and LOL can be in a stable state simultaneously with the injection duration long enough. With the increase of ambient density and ambient temperature, the LOL and LL decreases, the influence of ambient temperature on the LOL is greater than the effect on the LL. For the conditions where the combustion LL is shorter than the LOL, there will be more interspace for the mixing of air and fuel, and the fuel vaporization has completed before the fuel reaches the combustion region. For the conditions where the LL is longer than the LOL, there will be an overlap between liquid phase and combustion flame. The flame and liquid phase will interact with each other at these conditions. The vaporization of the liquid fuel is enhanced by the heat of the combustion and the combustion rate is reduced by the vaporization cooling. In addition, with the increase of cetane number of fuel density, the difference between LOL and liquid length became smaller and the decrease of LOL is greater than the decrease of LL. The physical and chemical properties of fuel have little effect on the difference between LOL and LL, when the injection pressure is low and the ambient oxygen concentration is high.

Phosphodiesterase 4D contributes to angiotensin II-induced abdominal aortic aneurysm through smooth muscle cell apoptosis

Gao Ran,Guo Wenjun,Fan Tianfei,Pang Junling,Hou Yangfeng,Feng Xiaohang,Li Bolun,Ge Weipeng,Fan Tianhui,Zhang Tiantian,Lu Jiakai,Jing He,Jin Mu,Yan Chen,Wang Jing 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Abdominal aortic aneurysm (AAA) is a permanent expansion of the abdominal aorta that has a high mortality but limited treatment options. Phosphodiesterase (PDE) 4 family members are cAMP-specific hydrolyzing enzymes and have four isoforms (PDE4A-PDE4D). Several pan-PDE4 inhibitors are used clinically. However, the regulation and function of PDE4 in AAA remain largely unknown. Herein, we showed that PDE4D expression is upregulated in human and angiotensin II-induced mouse AAA tissues using RT-PCR, western blotting, and immunohistochemical staining. Furthermore, smooth muscle cell (SMC)-specific Pde4d knockout mice showed significantly reduced vascular destabilization and AAA development in an experimental AAA model. The PDE4 inhibitor rolipram also suppressed vascular pathogenesis and AAA formation in mice. In addition, PDE4D deficiency inhibited caspase 3 cleavage and SMC apoptosis in vivo and in vitro, as shown by bulk RNA-seq, western blotting, flow cytometry and TUNEL staining. Mechanistic studies revealed that PDE4D promotes apoptosis by suppressing the activation of cAMP-activated protein kinase A (PKA) instead of the exchange protein directly activated by cAMP (Epac). Additionally, the phosphorylation of BCL2-antagonist of cell death (Bad) was reversed by PDE4D siRNA in vitro, which indicates that PDE4D regulates SMC apoptosis via the cAMP-PKA-pBad axis. Overall, these findings indicate that PDE4D upregulation in SMCs plays a causative role in AAA development and suggest that pharmacological inhibition of PDE4 may represent a potential therapeutic strategy.

Paleoenvironmental changes of source rocks from the Carboniferous to Permian sediments of the Mahu Sag, Junggar Basin, China

Feng Chong,Ma Mingze,He Wenjun,Li Teng,Wu Qiuyu,Zhang Zexin,Zhao Haiyang 한국자원공학회 2020 Geosystem engineering Vol.23 No.5

There are four sets of source rocks from Carboniferous (C) to Permian in Mahu Sag, and the paleoenvironment is the decisive factor for the differences of source rocks. In order to study the controlling effect of paleoenvironmental evolution on the change of source rock properties, the major, trace elements and the total organic carbon (TOC) of 47 core samples from four sets of source rocks were tested. The results indicate that the paleoenvironmental evolution of these four sets of source rocks from C to Permian in Mahu Sag can be divided into five stages. At the end of C and the early stage of deposition of Wuerhe formation (P2w), the paleo climate became warm and humid, and the salinity of water body became small. Meanwhile, the oxidizability of water body gradually became stronger. At the deposition stage of Jiamuhe Formation (P1j), Fengcheng Formation (P1f) and the late stage of deposition of P2w, the paleo climate gradually became hot and dry, and the salinity of water body gradually increased. Meanwhile, the reducibility of water body became stronger. The paleoenvironmental factors controlling the abundance of organic matter in source rocks are different in different stages.

Carotid stiffening predicts cardiovascular risk stratification in mid-life: non-invasive quantification with ultrafast ultrasound imaging

Zhengqiu Zhu,Lingshan Chen,Wenjun Liu,Yiyun Wu,Chong Zou,Xinyi Zhang,Shanshan He,Yinping Wang,Bixiao Shen,Xuehui Ma,Hui Gao,Yun Luan,Hui Huang 대한초음파의학회 2022 ULTRASONOGRAPHY Vol.41 No.3

Purpose: The present study investigated the association between Systematic COronary Risk Evaluation (SCORE)-estimated cardiovascular risk and carotid stiffening in a middle-aged population using ultrafast pulse wave velocity (ufPWV).Methods: This study enrolled 683 participants without known cardiovascular disease or diabetes mellitus who underwent ufPWV measurements. Clinical interviews, physical examinations, laboratory findings, carotid intima-media thickness (cIMT), pulse wave velocity (PWV) at the beginning of systole (PWV-BS), and PWV at the end of systole (PWV-ES) were assessed. Each participant underwent an assessment of SCORE risk based on major cardiovascular risk factors (CVRFs), including age, sex, smoking, systolic blood pressure (SBP), and total cholesterol (TC). Crude and adjusted odds ratios (ORs) with 95% confidence intervals and ordinal logistic regression were used. Overall CVRFs were adjusted to assess ORs.Results: cIMT and carotid stiffening in PWV-BS and PWV-ES were significantly different between sex subgroups (all P<0.05), but only PWV-ES increased gradually in age and SCORE-estimated risk subgroups (all P<0.05). Compared with cIMT (r=0.388, P<0.001) and PWV-BS (r=0.159, P<0.001), PWV-ES was more strongly correlated with SCORE categories (r=0.405, P<0.001). Higher PWV-ES values were associated with SCORE categories independently of sex, SBP, TC, and smoking in moderate-risk and high-risk subgroups (OR, 1.63; P<0.001 and OR, 2.12; P=0.024, respectively), but were not independent of age in all risk subgroups (all P>0.05).Conclusion: Carotid stiffening quantified by ufPWV is linked to SCORE categories, and elevated PWV-ES may aid in cardiovascular risk stratification.