A Dynamic Semi Parametric Panel Spatial Lag Model for Brain Drain and Economic Stability Based on the Security Perspective

Shengming Chen,Yabin Zhang,Azhong Ye 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.10

In this article, the authors research on the effect of international mobility of talent impact on Chinese economic development based on nonlinear relationship. From the perspective of the heterogeneity of human capital, this article introduces brain drain into a production function and analyzes the relationship between brain drain and economic development of the home country, and this paper draws an conclusion that moderate brain drain enhance the economic development of home country, but the unlimited brain drain will weaken the home country’s production capacity. On the contrary, it will cause the loss of economic of the home country. On the other hand, this article use Chinese Provincial Panel Data during 1997-2014 to construct the indicators of brain drain, and then use dynamic semi-parametric spatial lag model to empirical test the above inference. And find that there is indeed optimal level of brain drain in our country, but the level of the eastern coastal provinces is too high which inhibit the economic development of this region. Therefore, develop differentiated brain drain policies for coastal and inland, be a reasonable guide to the transnational flow of talent is important to increase China's economic.

Nonlinear Cascade Control for a New Coaxial Tilt-rotor UAV

Shengming Li,Lin Feng,Zongyang Lv,Yuhu Wu,Yingshun Li 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9

This paper proposes a nonlinear control strategy for a newly-designed coaxial tilt-rotor (CTR) unmanned aerial vehicle (UAV), which is a special class of tilt-rotor (TR) UAVs with two pairs of coaxial rotors, two servos, and a rear rotor. The CTRUAV is an underactuated system, and the controller is designed in cascade form. The proposed controller includes two sub-controllers: an inner-loop attitude controller and an outer-loop velocity controller. Each sub-controller is proposed by using a backstepping-like feedback linearization method to control and stabilize the CTRUAV. The developed control strategy can realize the motion control for the CTRUAV. The asymptotic stability of the resulting closed-loop system is analyzed by the Lyapunov method. Finally, simulations and real flight tests are performed to validate the effectiveness of the proposed control system.

Provisioning of QoS Adaptability in Wired-Wireless Integrated Networks

Mian Guo,Shengming Jiang,Quansheng Guan,Huachao Mao 한국통신학회 2013 Journal of communications and networks Vol.15 No.1

The increasing number of mobile users and the popularity of real-time applications make wired-wireless integrated network extremely attractive. In this case, quality of service (QoS)adaptability is particularly important since some important features of the integrated network call for QoS adaptability, such as mobility, bursty applications and so on. Traditional QoS schemes include integrated service (IntServ) and differentiated service (DiffSev) as well as their variants. However, they are not able to balance well between scalability and QoS granularity. For example,IntServ faces the scalability problem, while DiffServ can only provide coarse granular QoS. In addition, they are also unable to efficiently support QoS adaptability. Therefore, a per-packet differentiated queueing service (DQS) was proposed. DQS was originally proposed to balance between scalability and QoS granularity in wired networks and then extended to wireless networks. This paper mainly discusses how to use DQS to support QoS adaptability in wired-wireless integrated networks. To this end, we propose a scheme to determine dynamic delay bounds, which is the key step to implement DQS to support QoS adaptability. Simulation studies along with some discussions are further conducted to investigate the QoS adaptability of the proposed scheme, especially in terms of its support of QoS adaptability to mobility and to bursty real-time applications.

Experimental studies on elastic cooling and pyromagnetic effect ofpolyvinyl chloride sheets with defects

Yingshe Luo,Shengming Chen,Liang Zhang,Jianxin Su,Yongzhong Zhang3,Shuling Luo 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.3

Polyvinyl Chloride (PVC) sheets were made into samples with precast defects for uniaxial tensile test. The tests are carried out under room temperature with conditions of same displacement rate but different defect sizes or of same defect but different displacement rates. The local nonuniform temperature field on whole deformation area of specimen is recorded with a thermal infrared imager and the whole coupling magnetic field with thermal changes in experiments is detected and measured by a self-developed sensors system. The experimental results show that, in a complete tensile test process of PVC samples, the temperature reduction phenomenon emerges firstly in its elastic deformation stage (areas) that temperature of specimen is cooler than room temperature. And then in viscoplastic deformation period (areas), the temperature increases sharply to be obviously higher than room temperature due to the thermo-mechanical coupling effection of tensile load and viscoplastic deformation heat. These thermal variations lead a coupling pyromagnetic effect occur and the effect intensity is dependent strongly on the strain rate and/or the size of defects. The tem\-perature prejudgment conditions for materials yield are preliminary discussed based on this effect.

Removal of malachite green in aqueous solution by adsorption on sawdust

Yinghua Song,Sheguang Ding,Shengming Chen,Hui Xu,Ye Mei,Jianmin Ren 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12

A new adsorbent was synthesized from sawdust, a forest residue, in which methanol was used as a solvent and triethylamine as a modification agent under the following optimum conditions: 25 oC of reaction temperature, 1 : 8.75 of the ratio of sawdust to triethylamine (g :mL) and 1 hour of reaction time. The adsorption capacity of this adsorbent for malachite green was improved by 632.98% in contrast to that of the unmodified sawdust under the same adsorption conditions. Factors affecting the adsorption behavior of this adsorbent for malachite green, such as pH value, adsorption time, temperature and initial dye concentration, were evaluated through experiments in a batch system. The results indicated that the maximum adsorption capacity can be achieved at 5.08 of pH value and adsorption equilibrium can be reached in 6 hours. It was also found that the higher the temperature, the higher the adsorptive capacity would be. The Freundlich isotherm model provides a better description for the adsorption equilibrium when compared with the Langmuir equation in the conditions of the present study. Additionally, to examine the controlling mechanisms of the process, kinetic equations of the mass transfer and chemical reaction, the pseudo-first order model, the pseudo-second order model and the intraparticle diffusion model were used to correlate the experimental data respectively. The adsorption process of malachite green on sawdust tended to be controlled simultaneously by film mass transfer and intra-particle diffusion and it accompanied chemical reactions. It showed that the sawdust modified with triethylamine had good performance for cationic dye and can be used as a biomass adsorbent to treat dyes-containing wastewater with high quality.

Experimental studies on elastic cooling and pyromagnetic effect of polyvinyl chloride sheets with defects

Luo, Yingshe,Chen, Shengming,Zhang, Liang,Su, Jianxin,Zhang, Yongzhong,Luo, Shuling 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.3

Polyvinyl Chloride (PVC) sheets were made into samples with precast defects for uniaxial tensile test. The tests are carried out under room temperature with conditions of same displacement rate but different defect sizes or of same defect but different displacement rates. The local nonuniform temperature field on whole deformation area of specimen is recorded with a thermal infrared imager and the whole coupling magnetic field with thermal changes in experiments is detected and measured by a self-developed sensors system. The experimental results show that, in a complete tensile test process of PVC samples, the temperature reduction phenomenon emerges firstly in its elastic deformation stage (areas) that temperature of specimen is cooler than room temperature. And then in viscoplastic deformation period (areas), the temperature increases sharply to be obviously higher than room temperature due to the thermo-mechanical coupling effection of tensile load and viscoplastic deformation heat. These thermal variations lead a coupling pyromagnetic effect occur and the effect intensity is dependent strongly on the strain rate and/or the size of defects. The temperature prejudgment conditions for materials yield are preliminary discussed based on this effect.

Provisioning of QoS Adaptability in Wired-Wireless Integrated Networks

Guo, Mian,Jiang, Shengming,Guan, Quansheng,Mao, Huachao The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.1

The increasing number of mobile users and the popularity of real-time applications make wired-wireless integrated network extremely attractive. In this case, quality of service (QoS) adaptability is particularly important since some important features of the integrated network call for QoS adaptability, such as mobility, bursty applications and so on. Traditional QoS schemes include integrated service (IntServ) and differentiated service (DiffSev) as well as their variants. However, they are not able to balance well between scalability and QoS granularity. For example, IntServ faces the scalability problem, while DiffServ can only provide coarse granular QoS. In addition, they are also unable to efficiently support QoS adaptability. Therefore, a per-packet differentiated queueing service (DQS) was proposed. DQS was originally proposed to balance between scalability and QoS granularity in wired networks and then extended to wireless networks. This paper mainly discusses how to use DQS to support QoS adaptability in wired-wireless integrated networks. To this end, we propose a scheme to determine dynamic delay bounds, which is the key step to implement DQS to support QoS adaptability. Simulation studies along with some discussions are further conducted to investigate the QoS adaptability of the proposed scheme, especially in terms of its support of QoS adaptability to mobility and to bursty real-time applications.

A Dual Buck Three-Level PV Grid-Connected Inverter

Baojian Ji,Feng Hong,Jianhua Wang,Shengming Huang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

The use of a PV grid-connected inverter with non-isolated topology and without a transformer is good for improving conversion efficiency; however, this inverter has become increasingly complicated for eliminating leakage current. To simplify the complicated architecture of traditional three-level dual buck inverters, a new dual Buck three-level PV grid-connected inverter topology is proposed. In the proposed topology, the voltage on the grounding stray capacitor is clamped by large input capacitors and is equal to half of the bus voltage; thus, leakage current can be eliminated. Unlike in the traditional topology, the current in the proposed topology passes through few elements and does not flow through the body diodes of MOSFET switches, resulting in increased efficiency. Additionally, a multi-loop control method that includes voltage-balancing control is proposed and analyzed. Both simulation and experimental results are demonstrated to verify the proposed structure and control method.

A Family of Non-Isolated Photovoltaic Grid Connected Inverters without Leakage Current Issues

Baojian Ji,Jianhua Wang,Feng Hong,Shengming Huang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

Transformerless solar inverters have a higher efficiency than those with an isolation link. However, they suffer from a leakage current issue. This paper proposes a family of single phase six-switch transformerless inverter topologies with an ac bypass circuit to solve the leakage current problem. These circuits embed two unidirectional freewheeling current units into the midpoint of a full bridge inverter, to obtain a freewheeling current path, which separates the solar panel from the grid in the freewheeling state. The freewheeling current path contains significantly fewer devices and poor performance body diodes are not involved, leading to a higher efficiency. Meanwhile, it is not necessary to add a voltage balancing control method when compared with the half bridge inverter. Simulation and experiments are provided to validate the proposed topologies.

Zn-MOF loading Cu2O cube to construct hierarchical solid cage to improve photocatalytic hydrogen evolution

Jing Xu,Zezhong Li,Zhenlu Liu,Shengming Xu,Xinyu Liu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

A novel composite is constructed by loading ZIF-8 on Cu2O by in situ growth. By visible light driven semiconductorand p-p* conjugation effect of the metal–organic framework, the migration ability of photogeneratedcarriers is improved, and electrons are accumulated to participate in hydrogen ionreduction. The superior hydrogen evolution performance (981.8 lmolg1h1) and stability test indicatethat the coupling of ZIF-8 and semiconductor Cu2O successfully improves the catalytic capacity of thematerial. Cu2O provides a place to stimulate activity for ZIF-8 with high specific surface area. The electrontransfer mechanism in composites is studied by electrochemical and spectroscopy methods. This workalso provides a new opportunity for the in-situ growth of metal–organic frame materials onto singlemetaloxides.