The effectiveness of private tutoring: students’ perceptions in comparison with mainstream schooling in Hong Kong

Shengli Zhan,Mark Bray,Dan Wang,Chad Lykins,Ora Kwo 서울대학교 교육연구소 2013 Asia Pacific Education Review Vol.14 No.4

This paper examines Hong Kong students’ perceptions on the effectiveness of private supplementary tutoring relative to mainstream schooling. Drawing on survey and interview data, it shows that large proportions of secondary school students receive private tutoring. Students generally perceive private tutoring and private tutors to be more effective in the provision of examination support compared with mainstream schooling and teachers. However, perceptions vary according to students’ self-reported academic levels and motives for taking private tutoring. The operations of the parallel sector of private tutoring have significant implications for the nature of schooling and therefore need to be considered by teachers and school administrators. The Hong Kong data contribute to the international analysis of private tutoring and add a significant component to the wider conceptual literature.

A novel test method for the aerodynamic performance of wind turbine airfoil using wind generated by a moving vehicle

Shengli Li,Jun Liang,Pan Guo,Xidong Wang,Panjie Li 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.32 No.6

Refer to wind turbine airfoil wind tunnel test and consider the characteristics of wind generated by a moving vehicle, a new test method for wind turbine airfoil aerodynamic performance is proposed in this paper. Because of the relativity of motion, the vehicle will generate a relative wind field in the process of motion. Thus, the aerodynamic performance of wind turbine airfoil can be investigated using a transiting test method. In this study, a transiting test method is systematically introduced, the processing method of test data is discussed in detail, and the influence of vehicle vibration and end plate on the test results is evaluated. Three independent repeated tests are conducted, and the influence of natural wind is analyzed to eliminate the instability effect. The feasibility of the proposed test method is then verified by comparing its results with the results of wind tunnel test.

Soft Network Coding in Wireless Two-Way Relay Channels

Shengli Zhang,Yu Zhu,Soung Chang Liew 한국통신학회 2008 Journal of communications and networks Vol.10 No.4

Application of network coding in wireless Two-Way Relay Channels (TWRC) has received much attention recently because its ability to improve throughput significantly. In traditional designs, network coding operates at upper layers above (including) the link layer and it requires the input packets to be correctly decoded. However, this requirement may limit the performance and application of network coding due to the unavoidable fading and noise in wireless networks. In this paper, we propose a new wireless network coding scheme for TWRC, which is referred to as soft network coding (SoftNC), where the relay nodes applies symbol-by-symbol soft decisions on the received signals from the two end nodes to come up with the network coded information to be forwarded. We do not assume further channel coding on top of SoftNC at the relay node (channel coding is assumed at the end nodes). According to measures of the soft information adopted, two kinds of SoftNC are proposed: amplify-and-forward SoftNC (AFSoftNC) and soft-bit-forward SoftNC (SBF-SoftNC). We analyze the both the ergodic capacity and the outage capacity of the two SoftNC schemes. Specifically, analytical form approximations of the ergodic capacity and the outage capacity of the two schemes are given and validated. Numerical simulation shows that our SoftNC schemes can outperform the traditional network coding based twoway relay protocol, where channel decoding and re-encoding are used at the relay node. Notable is the fact that performance improvement is achieved using only simple symbol-level operations at the relay node.

Prediction Model for unfavorable Outcome in Spontaneous Intracerebral Hemorrhage Based on Machine Learning

Shengli Li,Jianan Zhang,Xiaoqun Hou,Yongyi Wang,Tong Li,Zhiming Xu,Feng Chen,Yong Zhou,Weimin Wang,Mingxing Liu 대한신경외과학회 2024 Journal of Korean neurosurgical society Vol.67 No.1

Objective : The spontaneous intracerebral hemorrhage (ICH) remains a significant cause of mortality and morbidity throughout the world. The purpose of this retrospective study is to develop multiple models for predicting ICH outcomes using machine learning (ML). Methods : Between January 2014 and October 2021, we included ICH patients identified by computed tomography or magnetic resonance imaging and treated with surgery. At the 6-month check-up, outcomes were assessed using the modified Rankin Scale. In this study, four ML models, including Support Vector Machine (SVM), Decision Tree C5.0, Artificial Neural Network, Logistic Regression were used to build ICH prediction models. In order to evaluate the reliability and the ML models, we calculated the area under the receiver operating characteristic curve (AUC), specificity, sensitivity, accuracy, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR). Results : We identified 71 patients who had favorable outcomes and 156 who had unfavorable outcomes. The results showed that the SVM model achieved the best comprehensive prediction efficiency. For the SVM model, the AUC, accuracy, specificity, sensitivity, PLR, NLR, and DOR were 0.91, 0.92, 0.92, 0.93, 11.63, 0.076, and 153.03, respectively. For the SVM model, we found the importance value of time to operating room (TOR) was higher significantly than other variables. Conclusion : The analysis of clinical reliability showed that the SVM model achieved the best comprehensive prediction efficiency and the importance value of TOR was higher significantly than other variables.

The Aftermath of the US Space Resource Exploration and Utilization Act: What’s Left for China?

Shengli Jiang,Yun Zhao 이준국제법연구원 2018 Journal of East Asia and International Law Vol.11 No.1

The US Space Resource Exploration and Utilization Act 2015 aroused heated discussions. The international community has not yet reached consensus on the application of the concept of “common heritage of mankind” in the Moon Agreement. In accordance with the non-appropriation principle in the Outer Space Treaty, outer space is not subject to national appropriation. However, there is a need to balance the common interests of the international society and the interests of the States and private entities which invest heavily in the space resource exploration. The unilateral approach of the US by adopting a national law is not an ideal way to deal with space resource exploration. As a major space-faring nation, China should take a proactive approach in both national legislation and international cooperation in this field. At the international level, China should consider establishing an appropriate international regime for space resource management.

Multi-Function Distributed Generation with Active Power Filter and Reactive Power Compensator

Shengli Huang,Jianguo Luo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents a control strategy for voltage-controlled multi-function distributed generation (DG) combined with an active power filter (APF) and a reactive power compensator. The control strategy is based on droop control. As a result of local nonlinear loads, the voltages of the point of common coupling (PCC) and the currents injecting into the grid by the DG are distorted. The power quality of the PCC voltage can be enhanced by using PCC harmonic compensation. In addition, with the PCC harmonic compensation, the DG offers a low-impedance path for harmonic currents. Therefore, the DG absorbs most of the harmonic currents generated by local loads, and the total harmonic distortion (THD) of the grid connected current is dramatically reduced. Furthermore, by regulating the reactive power of the DG, the magnitude of the PCC voltage can be maintained at its nominal value. The performance of the DG with the proposed control strategy is analyzed by bode diagrams. Finally, simulation and experimental results verify the proposed control strategy.

Efficient Decentralized Multirobot Task Allocation for Maximizing Total Assignments

Shengli Wang,Youjiang Liu,Yongtao Qiu,Jie Zhou 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

This paper addresses the decentralized task allocation problem of multirobot systems, in which the objective is to maximize the total task assignments, i.e., the number of tasks that can be successfully executed by all robotic vehicles under the time constraints of tasks and battery limits of vehicles. Based on the state-of-the-art performance impact (PI) algorithm, a novel extension named PI for minimizing traveling time (PI-minTravel) is proposed in this paper. With the proposed PI-minTravel, tasks that are close enough to the last task of each vehicle are assigned to the vehicle first, so that the total traveling time of all vehicles can be minimized. Due to the limited fuel of each vehicle, less traveling time will leave more time to execute tasks, then more tasks can be executed, especially when the ratio of tasks to vehicles is high. Extensive simulation results show that the proposed PI-minTravel can assign more tasks and converge within fewer iterations compared with PI algorithm, while it can assign fewer tasks but converge within much fewer iterations compared with PI for maximizing assignments (PI-maxAss) algorithm.

Water-gas shift coupling with methanation over MO_x modified nanorod-NiO/γ-Al_2O_3 catalysts

Shengli Ma,Yizhuo Han,Yisheng Tan 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.4

Water-gas shift coupling with methanation was carried out over metal oxide modified nanorod-NiO/γ-Al_2O_3 catalysts prepared by grind-mixing method in a continuous flow type fixed-bed reactor. The effects of promoter type, Co_3O_4 content, and reaction pressure were investigated. From the experimental results, Co_3O_4 modified nanorod-NiO/g-Al_2O_3 catalyst exhibited better activity than NiO–CuO/g-Al_2O_3and NiO–Fe_2O_3/g-Al_2O_3 with molar ratio of CO/H_2/H_2O = 3:1:1 at 593 K and atmospheric pressure. The addition of 10 wt%Co_3O_4 to nanorod-NiO/γ-Al_2O_3 catalyst was optimum. The CO conversion of 50 wt%NiO–10 wt%Co_3O_4/γ-Al_2O_3 catalyst was 7.8% and the CH_4 selectivity reached 83.2%. The NiO–MO_x/γ-Al_2O_3 catalysts were analyzed by X-ray diffraction, temperature programmed reduction and thermogravimetry techniques.

Natural wind impact analysis of transiting test method to measure wind pressure coefficients

Shengli Li,Lulu Liu,Pan Guo,Xidong Wang 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.2

Building wind pressure coefficient transiting test is a new method to test the building wind pressure coefficient by using the wind generated by a moving vehicle, which is susceptible to natural wind and other factors. In this paper, the Commonwealth Advisory Aeronautical Research Council standard model with a scale ratio of 1:300 is used as the test object, and the wind pressure coefficient transiting test is repeated under different natural wind conditions to study the influence of natural wind. Natural wind is measured by an ultrasonic anemometer at a fixed location. All building wind pressure coefficient transiting tests meet the test conditions, and the vehicle’s driving speed is 72 km/h. The mean wind pressure coefficient, the fluctuating wind pressure coefficient, and the correlation coefficient of wind pressure are used to describe the influence of natural wind on the building wind pressure coefficient transiting test qualitatively and quantitatively. Some rules, which can also help subsequent transiting tests, are also summarized.

Research on Semantic Web Service Composition Based on Binary Tree

Shengli Mao,Hui Zang,Bo Ni 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.2

With the rapid development of cloud computing and service computing, Web services are combined to form the composite service with a large granularity is an important research direction at present. The current service composition methods have the problems of low composition efficiency and accuracy, this paper proposes a semantic Web service composition method based on the binary tree. This method uses the ontology semantic reasoning relationship and binary tree theory to composite Web services. The composition relations between Web service interfaces are mainly considered. The approach can enhance the efficiency and accuracy of service composition, and the experiments are used to validate and analyze the proposed methods.