PLASMA ELECTROLYTIC OXIDATION COATING ON 6061 AL ALLOY USING AN ELECTROLYTE WITHOUT ALKALI IONS

Plasma electrolytic oxidation (PEO) technique is well known to use for modifying the surface of valve metal such as Al, Mg and Ti, which improves mechanical and corrosion resistance properties. PEO is an electrochemical process of oxidation by creating micro-discharges on the surface of metal immersed in an electrolyte under applying a high voltage. Electrolyte used in PEO process is almost based on alkali ions such as Na ion. The report on PEO process using free-alkali ion is very rare. In this study, the oxide layer on 6061 Al alloy was produced in a free-alkali ion electrolyte containing calcium phosphate and ammonia water by PEO method. Microstructure, micro-hardness and corrosion resistance of PEO coated were investigated and discussed. Surface morphology analysis indicated the coating characterized by micro-pores, pan-cakes like, and micro-crakes with pore size and percentage of pores on coating surface are smaller than 1 mm and 2.5 %, respectively. Micro-hardness and corrosion resistance of PEO coated are greatly improved compared to the bare Al alloy. Free-alkali-ions in oxide layer coated on Al alloy is important for many applications today

Using real interpolation method for adaptive identification of nonlinear inverted pendulum system

In this paper, we investigate the inverted pendulum system by using real interpolation method (RIM) algorithm. In the first stage, the mathematical model of the inverted pendulum system and the RIM algorithm are presented. After that, the identification of the inverted pendulum system by using the RIM algorithm is proposed. Finally, the comparison of the linear analytical model, RIM model, and nonlinear model is carried out. From the results, it is found that the inverted pendulum system by using RIM algorithm has simplicity, low computer source requirement, high accuracy and adaptiveness in the advantages

Red-emitting Ba2Si5N8Eu2+ conversion phosphor: A new selection for enhancing the optical performance of the in-cup packaging MCW-LEDs

In this research, the influence of the red-emitting Ba2Si5N8Eu2+ convention phosphor on the optical performance of the 7,000K and 7,700K in-cup packaging multi-chip white LEDs (MCW-LEDs) is investigated. The effect of the red-emitting Ba2Si5N8Eu2+ convention phosphor is demonstrated based on Mie Theory by Mat Lab and Light Tools software. The research results indicated that the optical performance of MCW-LEDs was crucially affected by the red-emitting Ba2Si5N8Eu2+ phosphor's concentration. This paper provides an essential recommendation for selecting and developing the phosphor materials for MW-LEDs manufacturing.Web of Science51art. no. 148615

Energy cost savings based on the UPS

Energy-saving, improving energy efficiency, and finding a new efficient way to use energy are considered as an urgent problem in over the world. In this paper, we consider the economics of energy use in combination with energy storage units where two forms of electricity exist in the power system. Then the problem of optimizing the installation capacity (to optimize the investment costs for energy storage) is presented and investigated in connection with the conversion systems. The topic opens a very significant result, including the introduction of a mathematical model to calculate the simulation in optimizing the installation capacity of the equipment in the system, multi-source power, as well as voltage and power stability benefits

Toward An IoT-based Expert System for Heart Disease Diagnosis

IoT technology has been recently adopted in the healthcare system to collect Electrocardiogram (ECG) signals for heart disease diagnosis and prediction. However, noises in collected ECG signals make the diagnosis and prediction system unreliable and imprecise. In this work, we have proposed a new lightweight approach to removing noises in collected ECG signals to perform precise diagnosis and prediction. First, we have used a revised Sequential Recursive (SR) algorithm to transform the signals into digital format. Then, the digital data is proceeded using a revised Discrete Wavelet Transform (DWT) algorithm to detect peaks in the data to remove noises. Finally, we extract some key features from the data to perform diagnosis and prediction based on a feature dataset. Redundant features are removed by using Fishers Linear Discriminant (FLD). We have used an ECG dataset from MIT-BIH (PhisioNet) to build a knowledge-base diagnosis features. We have implemented a proof-of concept system that collects and processes real ECG signals to perform heart disease diagnosis and prediction based on the built knowledge base

System Performance Analysis of Half-Duplex Relay Network over Rician Fading Channel

In this paper, the system performance of an amplify-and-forward (AF) relaying network over Rician Fading Channel is proposed, analyzed and demonstrated. For details this analysis, the energy and information are transferred from the source to the relay nodes by two methods: 1) time switching protocol and 2) power splitting protocol. Firstly, due to the constraint of the wireless energy harvesting at the relay node, the analytical mathematical expressions of the achievable throughput and the outage probability of both schemes were proposed and demonstrated. After that, the effect of various system parameters on the system performance is rigorously studied with closed-form expressions for the system performance. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions. The numerical results demonstrated the effect of various system parameters, such as energy harvesting time, power splitting ratio, source transmission to noise power, and the threshold value, on the system performance of AF wireless relay nodes. The results show that the analytical mathematical and simulated results match for all possible parameter values for both schemes

Organizational Culture Factors Affect Employees’ Organizational Commitment: A Research in Ho Chi Minh City Logistics Enterprises, Vietnam

Research aims: The research aims to evaluate several factors of organizational culture affecting the organizational commitment of employees in logistics enterprises in Ho Chi Minh City (Vietnam).Design/Methodology/Approach: The data were collected based on a survey of respondents who were employees working at logistics enterprises in Ho Chi Minh City. The collected data, consisting of 227 survey questionnaires, were described through statistical analysis, checking Cronbach’s Alpha reliability assessment, employing Exploratory Factor Analysis (EFA), and testing the fit of the research model. Research findings: The results showcased that five components had a statistically significant impact on an employee’s organizational commitment, including (from high to low impact in order) consistency in governance policy, communication within the organization, training and development, rewards and recognition, and teamwork.Theoretical contribution/Originality: The study contributes to and supplements the array of organizational culture topics related to the commitment of employees at companies.Practitioner/Policy implication: The research contributes to the logistics companies' understanding of how to improve the organizational culture to maintain the loyalty of employees in the organization.Research limitation/Implication: The research limitation is that only Ho Chi Minh City logistics enterprises were chosen for the survey. However, there are many cities in Vietnam where logistics companies are located. Thus, the other research can be implemented in other regions in Vietnam and other countries for future studies

Novel dependencies of currents and voltages in power system steady state mode on regulable parameters of three-phase systems symmetrization

The unbalanced mode, negative/zero sequence, variation of real power are caused by the nonlinear or unbalanced loads increase the power transmission losses in distributing power systems and also harmful to the electric devices. Reactive power compensation is considered as the common methods for overcoming asymmetry. The critical issue in reactive power compensation is the optimal calculation of compensation values that is extremely difficult in complex circuits. We proposed a novel approach to overcome these difficulties by providing the creation of new analytical connections of the steady-state mode parameters (voltages, currents) depends on the controlled parameter for the arbitrary circuits. The base of our approach to reactive power compensation is the fractional-polynomial functions. We present a new description of the behavior of voltages and currents depending on the controlled parameters of the reactive power compensation devices, and we prove its effectiveness

Practical Solutions to Ensure the Schedule Management of Ho Chi Minh City Urban Railway Project in Vietnam: Survey of Expert's Opinions

The development of the construction industry is considered to be a significant factor contributing to the economic growth of states and countries. However, many studies have shown that the quality of time and schedule management on civil and construction projects has generally been poor. Thus, it is essential to investigate factors that significantly affect the project schedule. This research aims to examine the practice of time management on a particular construction transport project in a developing country, the urban railway project in Ho Chi Minh City, Vietnam, with its six main lines. The implementation of this project began in 2010, but so far, only two lines have been constructed. The implementation process has been struck by many difficulties leading to the slow implementation of the entire urban railway system. To investigate the main causes leading to project delays, a research survey was carried out in three main stages: (1) a questionnaire was designed (2) data was collected with the participation of experts, and (3) an analysis of the data verification of the research model. Then, the analytical hierarchy process approach was applied to assess the priority level of the proposed solutions to ensure the effectiveness of the schedule of the entire urban railway project