XIN Hong-tao;WU Guang-yao;WEN Zhi;LEI Hao;LIN Fu-chun
Chinese Journal of Magnetic Resonance,2021,Vol 38,No. 01
Magnetic resonance imaging (MRI) studies have documented that there were structural abnormalities in acquired immunodeficiency syndrome (AIDS) patients. Although the long-term survival rate of AIDS patients can be improved by the combined antiretroviral therapy (cART), little is known about the effect of cART on brain structural alterations in AIDS patients. In this study, three-dimensional high-resolution brain structure MRI and voxel-based morphometric methods were used to explore the effects of cART on brain gray matter volume in AIDS patients. The results indicate that cART may effectively mitigate the occurrence of abnormal brain structure in AIDS patients, emphasizing the importance of early initiation of cART.
WU Wentao;PENG Zhouhua;WANG Dan;LIU Lu;JIANG Jizhou;REN Shuai
Chinese Journal of Ship Research,2021,Vol 16,No. 01
Objectives Focusing on the model uncertainties of unmanned surface vehicles (USVs) and unknown marine environmental disturbances, an anti-disturbance target-tracking control algorithm based on extended state observer (ESO) is proposed for twin-screw USVs.
Methods At the kinematic level, a guidance law based on the principle of constant bearing is presented for USVs. At the kinetic level, aiming at model uncertainties and unknown disturbances, anti-disturbance control laws for surge velocity and yaw angular velocity based on ESOs are designed to eliminate the problems caused by model uncertainties and unknown marine environmental disturbances. Finally, the stability of the proposed controllers is analyzed via input-to-state stability and cascade theory.
Results The results show that such a USV can effectively track the virtual target point using the proposed anti-disturbance target tracking controller.
Conclusions The effectiveness of the proposed control algorithm is verified via experimental results.
GAO Zeyu;ZHANG Peng;ZHANG Boshen;ZHANG Yuewen;SUN Peiting
Chinese Journal of Ship Research,2021,Vol 16,No. 01
Objective In light of problems such as the untimely condition monitoring and alarm, excessively large threshold bandwidth, and inaccurate condition evaluation parameters of intelligent ship power system equipment, an adaptive threshold method is proposed to monitor, alarm, and evaluate the conditions of such equipment.
Method First, a simulated annealing algorithm is used to optimize the support vector regression (SVR) prediction model and simulate the general state characteristic parameters of the power system equipment. Then, after the normal transformation of the modeling residual, in combination with the sliding time window, the adaptive threshold model is constructed. Finally, the exhaust gas temperature of the ship's main propulsion diesel engine is selected as the research object for example verification.
Results The results show that compared with the traditional fixed threshold, the adaptive threshold model has more compact bandwidth and good adaptability, and can identify abnormal phenomena in power system equipment in advance.
Conclusion This method improves the efficiency and threshold accuracy of monitoring and alarm systems and provides an effective means of early fault diagnosis and a more accurate basis for system status evaluation.
LOU Jiankun;WANG Hongdong;WANG Jianyao;YI Hong
Chinese Journal of Ship Research,2021,Vol 16,No. 01
[
Objectives] The performance of unmanned surface vehicles (USVs) is defined as the ability to complete specific tasks in specific environments within a given time scale as a result of the cooperation of multiple technical aspects. However, the traditional optimization method that focuses on a single part of the system provides a limited effect on improving the performance of USVs. [
Methods] For the features of an autonomous system of USVs, two main forms of the intelligent evolution of USVs are proposed from the perspective of algorithms: the evolution of algorithm functions and the evolution of algorithm parameters. In this case, a machine learning-based intelligent evolution method is proposed. An automatic USV control system that satisfies the requirements of intelligent evolution is then designed and tested in a sea trial. [
Results] The obstacle-avoidance task in the sea trial proves the capability and feasibility of the proposed method. [
Conclusion] The machine learning-based intelligent evolution of USVs is an effective way to continuously improve the performance of USVs, making it a worthy research topic with high application value.
FANG Hong;WANG Yimin
Foreign Economics & Management,2021,Vol 43,No. 01
Gender issue is the frontier research field of strategic management. Facing the deep and complex changes produced by the internationalization situation, it becomes a common choice to have females as the CEO of the company. As the decision-makers and leaders of internationalization strategies, how will female CEOs shape the internationalization dynamic process of Chinese companies? The previous studies have not conducted in-depth discussions on the cognitive logic and influence boundaries behind internationalization strategies. Based on the cognitive perspective of managers, this paper took the important feature of internationalization dynamic process—internationalization rhythm as the breakthrough point, and chose the dynamic panel data of A-share listed companies from 2008 to 2018 in Shanghai and Shenzhen stock exchanges to construct female CEOs’ explanation model to the internationalization rhythm of Chinese companies. Further, it examined the boundary effect of CEO genders on the internationalization rhythm from the perspectives of individual cognition and social cognition. The study has the following findings. Firstly, female CEOs have more comprehensive focus and more objective causal logic, and have relatively low perception of internationalization opportunities. So compared with male CEOs, female CEOs prefer regular and stable internationalization expansion. Secondly, with the improvement of CEOs’ educational level, the overconfidence of male CEOs is significantly reduced and the rational thinking is increased, which can build up relatively objective causal logic. Whereas, the educational level can enhance female CEOs’ self-confidence in their ability and decision-making behavior and adjust the focus of decision-making, and the gender difference in international decision-making will be reduced. Thirdly, female CEOs who pursue social role matching will pay more attention to team identity, and take into account the opinions of each member, thus increasing the degree of distraction and the degree of decision-making prudence. With the increase in the strength of TMT task-oriented faultline, female CEOs’ preference for regular and stable internationalization expansion model will be further enhanced. The main contributions of this paper are as follows. Firstly, it brings the focus deep into the internationalization dynamic process, and builds a more context-dependent theoretical model of the internationalization strategic behaviors of Chinese companies based on the characteristics of internationalization expansion rhythm of Chinese companies, to promote the deepening and integration of internationalization process theories. Secondly, based on the bounded rationality hypothesis, it returns to managers’ cognition itself and pays attention to the cognitive characteristics of decision-makers, such as focus of attention, causal logic, and social cognition, to deeply reveal the micro-cognition basis behind the leap-style internationalization process of Chinese companies and to respond to the call of micro-cognition movement in the strategic management field. Thirdly, it introduces the variables of CEO individual cognitive ability and TMT team structure to analyze the internal mechanism of CEOs’ decision logic and its effective interaction with TMT. This helps to deepen the understanding of the specific influencing mechanism of the internationalization rhythm of Chinese companies. Fourthly, under the situation of anti-globalization and trade protectionism sweeping the world, it has some practical guiding significance in optimizing the company governance structure and improving internationalization decision-making and other aspects.
