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Connectedness in the classroom is something that has often been mentioned in researches, but it is difficult to imagine what it is specifically. One may wonder whether or not connectedness is related to students’ academic performance. With the use of Social Network Analysis, this article models and measures the connectedness among classmates and its association with their academic performance. The class under study is at the undergraduate level and the research results show that its members have fairly high adhesion and no significant dispersion. Combined with the calculation of Pearson's index (r) in SPSS, the article has arrived at findings which prove to be identical with those of many international studies: the connectedness and the centrality of a student do not correlate with his or her academic performance. The findings of this article not only provide suggestions for classroom organization and extracurricular activities but also reveal new research directions in the field of education in Vietnam via network thinking.

The biological neural network signal flow is a complex process and difficult to interpret. The purpose of this study is to build a model of a simplified cerebellum neural network and investigate its working behavior in generating neuronal patterns. The model is constructed by referring to the neural anatomic structure of the mammal cerebellum and then simulated using Matlab Simulink software. The artificial neural network dimension is much smaller than the size of the real cerebellar neural network in mammal due to hardware simulation resource limitation. Thus, the utilization of extensivescale spiking neural networks is limited due to the grown of computational costs associated with propagating bio-realistic neural models. The parameters correlated with the neuron function also affect the biological plausibility of the spiking neural network. At the conclusion, we present the pattern generation of a cerebellum- like neural network and briefly explained why such patterns are generated.

The wheeled mobile robots have been widely applied in daily applications for its simplicity, robustness, stability and low-cost of manufacturing. Typically, PID controller is implemented to drive a mobile robot. However, the performance of the robot is greatly depended on the PID control parameters are tuned and the robustness of the mechanical system. Since the analog controllers were replaced by digital controller, PID control parameters could be automatically tuned to adapt the variation of the system parameters and operating condition. In this manuscript, a mathematical model is developed for a line following mobile robotic system which is used as a restaurant serving robot. The serving robot is controlled by an adaptive PID controller using Q-learning algorithm. The simulation and experimental results are compared to verify the advantage of the adaptive PID controller over classical PID controller.

This paper proposes a thermal design method for transmission coils with thermally conductive plastic plates considering load fluctuation of high-power wireless power transfer (WPT) systems. The high power transmission may cause melting of an insulation coating film of litz wires due to the heat generation of the windings and cores. For this reason, a cooling structure for the transmission coils is required. As the cooling structure, thermally conductive plastic plates with high thermal conductivity and resistivity are inserted between the core and the aluminum plates for an improvement of heat transfer. By representing the cooling structure as a thermal equivalent circuit, it facilitates a thermal design that takes into account load fluctuations. The thermal equivalent circuit is composed of a two-stage ladder circuit divided into the WPT system part and a cooling part. The peak temperature and the maximum allowable loss of load fluctuation are derived by simplifying the two-stage ladder circuit. In addition, the thickness of the thermally conductive plastic plates is designed by the design flowchart for the 15-kW WPT system.

This study aims to enhance the discussion about the usefulness of invasive animals for biodiversity assessment in Mekong Delta provinces. Data were used for the area of 5.331 km2 in Ca Mau Province [1]. The data covered the period 2017 – 2018. To implement this evaluation, the analyses were based on the scientific documents “Introduction to Invasive Species in Vietnam” of Vietnam Agency of Biodiversity Conservation and “The Aquatic Invasive Species Assessment and Management Plan” Massachusetts Department of Conservation and Recreation, and the working experiences of research group for the invasive species assessment [2, 3]. The results found two invasive animal species such as apple snail – Pomacea canaliculata (Lamarck, 1819) and Amazon sailfin catfish – Pterygoplichthys pardalis (Castelnau, 1855) [2]. These species mapped in the map of Ca Mau Province. The problem of invasive species has become an important issue of concern for the local government and community. However, if appropriate targets for ecosystem management planning is suggested, these “invaders” can be prevented the spread of invasive species.

Mô hình thông tin công trình (BIM) áp dụng cho vòng đời dự án xây dựng công trình hạ tầng kỹ thuật mang những đặc trưng riêng, khác biệt với việc áp dụng cho các dự án xây dựng công trình công nghiệp và dân dụng. Bài báo tập trung vào việc giới thiệu và phân tích ứng dụng BIM cho các công trình hạ tầng kỹ thuật, hay còn gọi là infra-BIM (theo cách gọi của Phần Lan), từ đó thảo luận chuyên sâu về việc phát triển ứng dụng BIM cho các công trình hạ tầng kỹ thuật tại Việt Nam thông qua những phân tích về môi trường pháp lý cho việc ứng dụng BIM tại Việt Nam, tổng quan tình hình ứng dụng BIM cho các công trình hạ tầng kỹ thuật tại Việt Nam và nêu ý kiến đề xuất việc thúc đẩy ứng dụng BIM bằng những nỗ lực trong việc hoàn thiện các cơ sở pháp lý, cũng như đẩy mạnh các dịch vụ BIM cho từng giai đoạn của quá trình thực hiện đầu tư xây dựng các công trình hạ tầng kỹ thuật. Nhận ngày 15/12/2017; sửa xong 29/12/2017; chấp nhận đăng 16/01/2018

As the era of industrial 4.0 coming, robotic technology has been applied in many aspects of human life. Putting robots in service business such as waiter robot serving in a restaurant is very promising industry in the near future. In this study, the authors present the development of a restaurant serving robot using double line-sensors following approach in combination with PID controller for stable speed outcome. The robot is designed by referring to the surveys on the size and appearance requirement at local restaurants. The serving robot is programmed to come to a specific table by mapping data. Based on the line reading algorithm from two LED array line sensors implemented on microcontroller, the robot follows the line marked on the floor to move to the desired table position and returns to the service counter after completing the task. In this study, we build the mathematical model for the robot and simulate the response when applying PID controller using Matlab Simulink. The set of PID parameters are found by applying PID Tune App from Simulink, and then implemented to microcontroller to regulate the pulse width voltage input to the motor.

Article

The evaluation of dynamic characteristics of rotating machinery such as natural frequency, mode shapes, stiffness and damping coefficients is very important and must be carried out in the beginning in the design and fabrication of any rotating machines. The fail estimation of these characteristics can lead to reducing the longevity or damaging of machinery. Therefore it is very essential to design and build a small test rig for performing the experimental tests in order to investigate the behaviors of the machinery. The characteristics of the test rig in detail are descripted first. It is followed by the introduction of the installed sensors and their specifications. Some preliminary tests have been performed to check the functions of the system.

Some countries concentrate to study on BIM as an effective tool in quantities taking-off and costs estimating. In contrast, due to special features of Vietnamese law regulations, issues on BIM application for these works are still not considered properly in Vietnam. Therefore, in this research, the authors would like to review studies performed on BIM uses on these works in Vietnam, and to analyze the necessities and difficulties when using BIM for automatically taking off quantities and estimating construction costs, then to propose technology methods for addressing this issue. Two methods are proposed to automatically calculate construction works quantities and costs based on models designed in Revit, more specifically, the first one is using Keynote to develop a database on components codes and to establish the components schedule in Revit; the second is using Dynamo to develop connection nodes between Revit models and Excel Sheets, facilitating the data export from Revit to Excel, then using Excel to adjust data in consistency with models.

In this paper, a novel single-stage boost inverter using one inductor is proposed for a grid-tied photovoltaic (PV) inverter. The proposed inverter shares one inductor with two boost converters by utilizing discontinuous current mode (DCM). The output voltage is controlled by the differential voltage between boost converters. Using this topology, the neutral point of the grid can be connected to a terminal of the solar panel. As a results, common-mode noise can be suppressed. The operation of the proposed inverter is confirmed with 100-W prototype with a DC input voltage of 100 V and an AC output voltage of 100 V. The output current THD is 1.4%.

Intrusion Detection System (IDS) has been used widely in network systems to detect malicious behaviors which can harm system or computers. However, in practical implementations, an IDS is a complex work and needs investing in the new infrastructure or in training new personnel. Therefore, it is inconsistent with the users who has a small network system. In this paper, we introduce an IDSCloud model as a solution to implementing a network IDS based on cloud computing. The IDSCloud provides network IDS as a service over the internet which can be simple in deployment, maintenance, scalability without investing in the new infrastructure.

Ho Chi Minh City (HCMC) is situated on the bank of the Saigon River in the southern part of Vietnam. The city with an area of 2,095 km2 is home to more than 7.95 million residents in 2014. The metropolitan area is the most important economic center in Vietnam, contributing approximately 20% of the country’s gross domestic product. Water supply in the city is derived from both surface and groundwater sources. Until now, groundwater is playing an important role to meet water demand of the city. In 2012, the total amount of water supply in HCMC was about 1.5 MCM/d, of which 44.67% was produced from groundwater. It is planned to reduce the amount of groundwater abstraction for water supply to 0.44 MCM/d (or 15.5% of the total water demand) by 2015 and to 0.10 MCM/d (or 2.7% of the total water demand) by 2020. High industrialization and urbanization resulted in the quick increase of water demands. Surface water production or development so far have not been able to meet the increasing demands. Besides, no-cost and uncontrolled abstraction has significantly increased rates and volumes of groundwater pumping in the HCMC. Groundwater is under threat due to salt-water intrusion, reduction of groundwater levels, and contamination. The excessive groundwater abstraction has also led to the land subsidence at some areas in the HCMC. The subsidence at the rate of few centimeters per year is measured at heavy pumped groundwater stations. This case study aims at synthesizing the situation of groundwater environment of HCMC to better understand the origin of stresses, current state, expected impacts, and responses needed to restore the healthy groundwater environment.