ISSN 0253-2778

CN 34-1054/N

2021 Vol. 51, No. 4

Management Science and Engineering
The optimal logistics service strategy choices between the platform and e-retailers
Liu Tianzhuo, Huang Rong, Yang Feng, Wang Manman
2021, 51(4): 259-274. doi: 10.52396/JUST-2021-0081
In the e-commerce market, the success of the hybrid online platform is well proven. The platform is not only an e-retailer but also provides online logistics services for other e-retailers in the platform. Logistics service is an indispensable link in e-commerce, and it also plays a vital role in promoting the online shopping. In our research, we analyze the impacts of logistics service sharing between the platform and the e-retailer and investigate the optimal strategy in two models. The study found that when the third-party logistics provider's logistics service level coordinates with logistics service fees and both are in the middle range, the platform and the e-retailer can achieve a logistics service sharing agreement, forming a win-win scenario. When the logistics service fee charged by the third-party logistics provider is too low, or the third-party logistics provider's logistics service is too high, both the platform and the e-retailer will choose the strategic mode of not sharing logistics service. Simultaneously, the third-party logistics provider's logistics service level promotes the logistics service level of the platform. Finally, numerical analysis is carried out to verify the equilibrium model and analyze the impacts of the equilibrium model's main parameters. Our study contributes to the growing body of research on the platform operation and provides management insights on firms' logistic service strategy choices.
Vocational interests and informal learning in the workplace: The mediating role of goal orientation
Weng Qingxiong, Chen Chen, Li Junyi, Niu Tingting
2021, 51(4): 275-287. doi: 10.52396/JUST-2020-0030
We used the social cognitive career theory to investigate how vocational interests affect informal learning behavior in the workplace by building a model with three different dimensions of vocational interests as independent variables and different goal orientation dimensions as mediating variables. Using a sample of 211 Chinese employees from different industries, results showed that investigative and enterprising vocational interests had positive effects, whereas realistic interests had a negative effect, on informal learning. Results also indicated that learning and performance-prove goal orientations positively affected informal learning, whereas performance-avoid goal orientations negatively affected informal learning. Further, each dimension of the goal orientation played a mediating role in the influence of vocational interests on informal learning. Findings of this study enhanced our understanding of the mechanism surrounding of how vocational interests influence informal learning and provided important new evidence for the theoretical and practical development of the relationships among interests, goals, and behaviors in the social cognitive career theory.
Corporate resistance to pandemic: Evidence from China
Li Tingfang, Wang Xiao
2021, 51(4): 288-298. doi: 10.52396/JUST-2021-0070
Based on the quarterly data of A-share listed firms between 2019 and 2020, we find that firms with lower leverage and higher cash holdings before perform better under the COVID-19 pandemic, suggesting that strong liquidity helps firms resist risks. In particular, cash holding affects firm performance through the channel of production. Secondly, we calculate firms' position in the global value chain based on a world input-output table and find that downstream firms perform better under the pandemic. Thirdly, to cope with future uncertainty, cash-holding willingness of firms increases significantly after the pandemic. All findings imply that firms need to improve their financial health to be more resilient toward negative shocks and policy makers need to improve the financial environment to satisfy firms' external financing need.
Engineering and Materials Science
Plane microscopic observation on instability of double emulsion clusters
Zhang Zhanhao, Qiu Yuheng, He Dongliang, He Liqun
2021, 51(4): 299-307. doi: 10.52396/JUST-2020-0023
Double emulsions have huge potential applications in many fields, but their wide use is limited by the instability. We have established a plane experimental observation method based on the microscope observation on the instability of double emulsion clusters to understand the key factors that affect the instability of droplets. A glass capillary device was used to produce the uniform monodisperse double emulsion droplets, and the dynamic information of the double emulsions was recorded through a microscope. We found that the instability of the double emulsions was caused together by diffusion and coalescence. And through the light curing experiment, the coalescence phenomenon of the internal droplets and the outer phase became visible. The experimental results show that the thicker the oil film thickness of the W/O/W droplets, the more difficult the coalescence of the inner droplets and the outer phase, and the more stable the double emulsions. The effect of glycerol on the stability of double emulsions was studied by changing the concentration of glycerol in the outer phase. We found that the stability time of the double emulsions increased with the decrease of the glycerol concentration, but when the glycerol concentration was reduced to 10 wt%, the stability of the double emulsions became worse. When the glycerol concentration was not less than 40 wt%, the instability of the double emulsions was more caused by the conversion of W/O/W droplets to O/W droplets. When the glycerol concentration was not more than 30 wt%, the instability of the double emulsions was more caused by the conversion of W/O/W droplets to W/W droplets. In addition, by using different surfactants, it was found that the double emulsions formulated with polyvinyl alcohol (PVA) had higher yield and a longer stable time.
The performance analysis on a novel purified PV-Trombe wall for electricity, space heating, formaldehyde degradation and bacteria in activation
Li Niansi, Liu Xiaoyong, Yu Bendong
2021, 51(4): 308-318. doi: 10.52396/JUST-2020-0018
On the one hand, PV-Trombe wall is a combined solar system that meets dual functions of space heating and electricity output, but the utilization on the recovered solar heat by PV-Trombe wall is very limited. On the other hand, thermal catalytic oxidation and thermal sterilization are two advanced air purification technologies and both they have huge application potential with solar heat. Therefore, a novel purified PV-Trombe wall for electricity, space heating, formaldehyde degradation and bacteria inactivation was proposed. Firstly, the system thermal and mass transfer model was established and verified by experimental data. Secondly, the comprehensive performance with the PV coverage ratio of 0 was analyzed. Finally, the effect of PV coverage ratio on the system performance was investigated. Accordingly, the main results were: ① Under PV coverage ratio of 0, the average daily air thermal efficiency and formaldehyde single-pass ratio were 0.46 and 0.35, respectively. Meanwhile, the total generated volume of clean air by formaldehyde degradation was 93.4 m3. Five kinds of bacteria were fully thermal inactivated for several hours. Accordingly, the total generated volume of clean air were 188.3, 173.0, 201.4, 189.9 and 200.2 m3 for E.coli, L.monocytogenes, L.plantarum, S.Senftenberg and S.cerevisiae, respectively. ② The PV coverage ratio played a different role on the system comprehensive performances. For specific performances, the PV coverage ratio only had a positive influence on electrical performance and had negative effect on other performances such as thermal, formaldehyde degradation and bacteria inactivation performances. However, considering the system comprehensive performances, the electrical energy was the additional product and the low PV coverage ratio was suggested. ③ The works could provide possible support to the prevention and control of COVID-19.
Development of the Ag nanoparticle-decorated Co3O4 electrode for high-performance hybrid Zn batteries
Shang Wenxu, Yu Wentao, Ma Yanyi, Tan Peng
2021, 51(4): 319-326. doi: 10.52396/JUST-2021-0049
The hybrid Zn battery is a promising electrochemical system integrating the redox reactions of transition metal oxides and oxygen in a single cell, through which high energy efficiency and energy density can be achieved simultaneously. However, the positive electrode usually suffers from unsatisfactory capacity utilization of the active material and poor oxygen reduction and evolution reaction activity. Here, a novel nano-structured Co3O4 electrode with the decoration of Ag nanoparticles is developed. Benefiting from the synergistic function between Ag nanoparticles and Co3O4 nanowires, the electric conductivity is improved and the morphology is optimized effectively. With this electrode, a hybrid Zn battery delivers five-step discharge voltage plateaus from 1.85 to 1.75, 1.6, 1.55, and 1.3 V, a high active material utilization ratio of 18%, and a low voltage gap of 0.69 V at 1 mA·cm-2. Moreover, it can operate stably for 500 cycles with a voltage gap increase of only 0.03 V at 10 mA·cm-2. This work brings up a novel electrode for an ultra-high performance hybrid Zn battery with both high active material utilization and outstanding oxygen electrocatalytic activity.
Information Science
Estimation based approximating control for wireless networked control systems
Liang Qipeng, Zhu Qiaohui, Kang Yu, Zhao YunBo
2021, 51(4): 327-334. doi: 10.52396/JUST-2020-1156
The control design and system analysis of wireless networked control systems with unknown round-trip delay characteristics are investigated. An estimation based approximating control strategy is proposed to stabilize the systems by using delay characteristics in a practically feasible way. The strategy first uses a delay transition probability estimator to obtain the delay characteristics estimation by measuring delay data online, and then uses an approximating controller to take advantage of the estimation. On this basis, a packet delay variation detector is designed, making the strategy adaptive to the variation of delay characteristics. The sufficient conditions to ensure the closed-loop system being mean-square uniformly ultimately bounded are given, with also the controller gain design method. The effectiveness of the proposed approach is verified numerically.
Recent advance in deep visual object tracking
Wang Ning, Xi Mao, Zhou Wengang, Li Li, Li Houqiang
2021, 51(4): 335-344. doi: 10.52396/JUST-2021-0037
Visual object tracking is an important branch in computer visions. In recent years, with the remarkable success of deep learning techniques, a series of deep tracking algorithms have emerged with impressive performances. In this paper, we review the recent development of deep learning based trackers. First, we revisit the development of tracking benchmarks in the last decade. These tracking datasets not only comprehensively help evaluate the tracking algorithms but also largely support the model training of deep trackers. Next, we discuss several representative tracking frameworks including deep correlation filter tracking, classification-based tracking networks, Siamese tracking networks, gradient-based tracking networks and Transformer based deep trackers. Finally, we conclude the paper and discuss the potential future research directions of the visual tracking.