Journal Articles - Engineering Technology - 2020

In this paper, stochastic fractal search method (SFS) is employed for solving the optimal reactive power flow (ORPF) problem with a target of optimizing total active power losses (TPL), voltage deviation (VD), and voltage stability index (VSI). SFS is an effective metaheuristic algorithm consisting of diffusion process and two update processes. ORPF is a complex problem giving challenges to applied algorithms by taking into account many complex constraints such as operating voltage from generators and loads, active and reactive power generation of generators, limit of capacitors, apparent power limit from branches, and tap setting of transformers. For verifying the performance, solutions of IEEE 30 and 118-bus system with TPL, VD, and VSI objectives are found by the SFS method with different control parameter settings. Result comparisons indicate that SFS is more favorable than other methods about finding effective solutions and having faster speed. As a result, it is suggested that SFS should be used for ORPF problem, and modifications performed on SFS are encouraged for better results.

Solar chimneys absorb solar radiation heat to create stack effect which induces airflow for natural ventilation of buildings. Solar chimneys have been studied mainly in two forms: vertical air channel and inclined one. In this paper, a solar chimney with a horizontal absorber surface was proposed. Its performance in term of the induced air flowrate through the channel and the thermal efficiency was predicted by a CFD (Computational Fluid Dynamic) model. Examined factors included the heat flux and major dimensions of the chimney: length of the absorber surface, gap of the air channel, and height and width of the inlet and outlet sections. The results show that increasing of all examined factors enhances the flowrate but has minor effect on the thermal efficiency. However, excessive large outlet width results in reduction of the flowrate and thermal efficiency due to appearance of reverse flow at the outlet.

In this paper, stochastic fractal search method (SFS) is employed for solving the optimal reactive power flow (ORPF) problem with a target of optimizing total active power losses (TPL), voltage deviation (VD), and voltage stability index (VSI). SFS is an effective metaheuristic algorithm consisting of diffusion process and two update processes. ORPF is a complex problem giving challenges to applied algorithms by taking into account many complex constraints such as operating voltage from generators and loads, active and reactive power generation of generators, limit of capacitors, apparent power limit from branches, and tap setting of transformers. For verifying the performance, solutions of IEEE 30 and 118-bus system with TPL, VD, and VSI objectives are found by the SFS method with different control parameter settings. Result comparisons indicate that SFS is more favorable than other methods about finding effective solutions and having faster speed. As a result, it is suggested that SFS should be used for ORPF problem, and modifications performed on SFS are encouraged for better results.

This study introduces a measure called coefficient of within-cluster proximity (CWP) to evaluate the similarity of probability density functions (DFs) within clusters. After surveying the under and upper, and the computational problems of CWP, a fuzzy clustering algorithm for DFs is proposed. This algorithm can determine the suitable number of clusters and find the probability for each DF to belong to specific cluster. The convergence of the algorithm is considered in theory and illustrated by the numerical examples. The algorithm is applied to image recognition. The results show strong advantages of it in comparison to other algorithms. They also indicate the potential of the proposed approach in application to the data of different types.

In the paper, a proposed particle swarm optimization (PPSO) is implemented for dealing with an economic load dispatch (ELD) problem considering the competitive electric market. The main task of the problem is to determine optimal power generation and optimal reserve generation of available thermal generation units so that total profit of all the units is maximized. In addition, constraints, such as generation limit and reserve limit of each unit, power demand and reserve demand, must be exactly satisfied. PPSO is an improved version of conventional particle swarm optimization (PSO) by combining pseudo gradient method, constriction factor and a newly proposed position update method. On the other hand, in order to support PPSO to reach good results for the considered problem, a new constraint handling method (NCHM) is also proposed for determining maximum reserve generation and correcting reserve generation. Three test systems with 3, 10 and 20 units are employed to evaluate the real performance of PPSO. In addition to the comparisons with previous methods, salp swarm optimization (SSA), modified differential evolution (MDE) and eight other PSO methods are also implemented for comparisons. Through the result comparisons, two main contributions of the study are as follows: (1) NCHM is very effective for PSO methods to reach a high success rate and higher solution quality, (2) PPSO is more effective than other methods. Consequently, NCHM and PPSO are the useful combination for the considered problem.

Ngày nay, Wifi là nền tảng phổ biến nên việc kết nối để liên lạc, trao đổi thông tin giữa các thiết bị điện tử bằng Wifi cần được xem xét theo hướng ứng dụng. Nghiên cứu này nhằm mục đích phát triển một hệ thống điển hình để giám sát và điều khiển trên nền công nghệ Wifi. Hơn nữa, kết hợp với ứng dụng phần mềm trên điện thoại thông minh giúp người dùng điều khiển được các hoạt động của vật thể di động bao gồm tiến, lùi và chuyển hướng trái - phải. Hệ thống điển hình này sử dụng mô-đun ESP8266, được cung cấp thông tin bằng các cảm biến gắn vào hệ thống. Mô-đun ESP8266 là thiết bị hỗ trợ Wifi, do đó, nó chuyển dữ liệu thu được từ cảm biến sang lưu trữ đám mây một cách dễ dàng. Vì vậy, người dùng hoàn toàn có thể theo dõi thông tin và cảm nhận dữ liệu mà không cần can thiệp thủ công.

In this study, the problem of optimal capacitor location and size determination (OCLSD) in radial distribution networks for reducing losses is unraveled by moth swarm algorithm (MSA). MSA is one of the most powerful meta-heuristic algorithm that is taken from the inspiration of the food source finding behavior of moths. Four study cases of installing different numbers of capacitors in the 15-bus radial distribution test system including two, three, four and five capacitors areemployed to run the applied MSA for an investigation of behavior and assessment of performances. Power loss and the improvement of voltage profile obtained by MSA are compared with those fromother methods. As a result, it can be concluded that MSA can give a good truthful and effective solution method for OCLSD problem.

In this paper, we estimated half-lives using semi-empirical formulae for isotopes with Z=100−126 in four α-decay chains, which can appear in the syntheses of the 309−312126 nuclei. The spontaneous fission half-lives were calculated using the Anghel, Karpov, and Xu models, whereas theα-decay ones were predicted using the Viola-Seaborg, Royer, Akrawy, Brown, modified formulae of Royer, Ni, and Qian approaches.Wefound that there are large differences among the spontaneous fission half-lives estimated using the Xu model and those calculated using the others, which are up to 50 orders of magnitude. The α-decay half-lives also have large uncertainties due to difference in either methods or uncertainties in nuclear mass and spin-parities. Subsequently, there is an argument in determination of α-emitters, especially for the 312126 isotope. On the other hand, the α-decay half-lives are in the range from a few microseconds (309−312126) to thousands of years (257−260Fm) in the decay chains. It was found that the half-lives are very sensitive to not only the shell closure but also the angular momentum in theα decay. For experiments, with relatively long half-lives (a few milliseconds), the 289−292Lv isotopes can be observed as evidences for syntheses of the unknown super-heavy 309−312126 nuclei. Furthermore, measurements for precise mass, fission barrier, and spin-parity are necessary to improve accuracy of half-life predictions for super-heavy nuclei.

Physalis angulata (PA) is a plant under the Solanaceae family playing an important role in the remedy of inflammatory symptoms such as asthma, hepatitis, dermatitis, rheumatism and treatment of several health disorders, such as cold, cough, fever, pain, malaria and nervous diseases. Besides, P. angulata has been used as a traditional medicine for amelioration of hyperglycemia. Thus, this study aimed to investigate mechanism of action of P. angulata for its anti-diabetic activity using an in vitro model. Ethanol extract of PA was prepared under the condition of ethanol 98% and ratio of ¼ (w/v) for 4 hours at 60°C. The concentrations of 50, 100, and 200 μg/mL of PA extract were used for all assays. The alpha-amylase inhibition was investigated via dinitrosalicylic acid assay. Glucose uptake was determined using LO-2 cell model. Radical scavenging activity was performed via 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)+ assays. Nitric oxide production was measured by Griess reaction, while cell viability was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The result showed that PA extract was able to inhibit alpha-amylase activity up to 56.6 ± 4.7% at the concentration of 200 μg/mL. Moreover, PA possessed glucose adsorption and glucose uptake capacities up to 2.2 ± 0.18 mM glucose/g extract and 156 ± 10.1%, respectively. In addition, PA extract scavenged 52.6 ± 3.5% DPPH and 59.7 ± 2.6% ABTS+ radicals and reduced NO production to 34.2 ± 3.8% from RAW264.7 cells. Consequently, P. angulata can be suggested as a pharmaceutical ingredient for the development of anti-diabetic agent.

In recent years, the transport of large packages with super weight from 100 tons to several thousand tons is no longer a difficult problem due to the continuous development of technology. Experienced transport companies, specializing in transporting heavy goods in Vietnam, have invested in very modern equipment and machinery such as self-propelled trailers of Cometto (Italy) in order to transport safely mentioned parcels of great economic value arrive at the requested location. This trailer can be self-propelled, does not need to use a tractor, and only needs to use a remote-control handheld device. Moreover, the trailer gear shaft can rotate 360 degrees. In particular, the hydraulic system supports trailers operating with high accuracy and absolute safety including functions such as 360-degree rotation, lifting, transmission, braking, etc. In order to improve the performance of trailers when actually used in large projects, an important detail in the trailer's hydraulic system has been inserted a throttle valve with to increase the safety of the hydraulic pump and the entire system as well as the safety of the goods that trailers are transporting. The trailer system has transported the rig with a capacity of up to 3,200 tons in Vietnam, the shipment of 15,000 tons in the world and beyond in the future.

In recent years, the transport of large packages with super weight from 100 tons to several thousand tons is no longer a difficult problem due to the continuous development of technology. Experienced transport companies, specializing in transporting heavy goods in Vietnam, have invested in very modern equipment and machinery such as self-propelled trailers of Cometto (Italy) in order to transport safely mentioned parcels of great economic value arrive at the requested location. This trailer can be self-propelled, does not need to use a tractor, and only needs to use a remote-control handheld device. Moreover, the trailer gear shaft can rotate 360 degrees. In particular, the hydraulic system supports trailers operating with high accuracy and absolute safety including functions such as 360-degree rotation, lifting, transmission, braking, etc. In order to improve the performance of trailers when actually used in large projects, an important detail in the trailer's hydraulic system has been inserted a throttle valve with to increase the safety of the hydraulic pump and the entire system as well as the safety of the goods that trailers are transporting. The trailer system has transported the rig with a capacity of up to 3,200 tons in Vietnam, the shipment of 15,000 tons in the world and beyond in the future.

A study is made to investigate the compression behavior of different nested tube systems made of mild steel under lateral compression. The nested tube systems including stacked groups of circular, rectangular and square tubes are built for application in narrow compressive zones. The deformation mode of these systems is observed and their lateral compression behavior are identified. The desirable stepwise energy absorption is obtained by designing the nested tube system. The load response revealed that there is no appearance of the peak compressive load in the case of a circular-circular tube (CCT) system, while a circular-rectangular tube (CRT) system offers bigger peak compressive load compared with that of a circular-square tube (CST). The energy absorptions of CCT and CRT systems are smallest and greatest, respectively. This study also estimates the energy absorption capacity of these system. By implementing the “plastic hinge line” concept of the modified simplified super folding element (MSSFE) theory and superposition principle, the analytical models predicting compressive load of the nested tube systems are introduced. The analytical investigations are compared with the data obtained from tests on these systems. Excellent correlation is observed between the theoretical and experimental data.

The buckling analysis of the embedded sinusoidal piezoelectric beam is evaluated using numerical method. The smart beam is subjected to external voltage in the thickness direction. Elastic medium is simulated with two parameters of spring and shear. The structure is modelled by sinusoidal shear deformation theory (SSDT) and utilizing energy method, the final governing equations are derived on the basis of piezo-elasticity theory. In order to obtaining the buckling load, the differential quadrature method (DQM) is used. The obtained results are validated with other published works. The effects of beam length and thickness, elastic medium, boundary condition and external voltage are shown on the buckling load of the structure. Numerical results show that with enhancing the beam length, the buckling load is decreased. In addition, applying negative voltage, improves the buckling load of the smart beam.

Wireless power transfer is considered as a novel solution for energy harvesting in wireless communication networks. In this paper, the system performance of the nonlinear energy harvesting based power splitting relaying in the fullduplex relaying sensor network is investigated. We considered the system model network with one source, one destination, and one relay node in both the amplifyandforward and decodeandforward modes. The closedform expressions of the system outage (OP) are analysed and derived for verifying system performance. Then, the correctness of the OP closedform expression is verified by using the Monte Carlo simulation. Furthermore, the influence of the primary system parameters on the system OP is suggested and investigated. The research results indicated that the simulation curves and the analytical curves overlapped, verifying the correctness of the analytical expressions.

By mimicking the biological evolution process, genetic algorithm (GA) methodology has the advantages of creating and updating new elite parameters for optimization processes, especially in controller design technique. In this paper, a GA improvement that can speed up convergence and save operation time by neglecting chromosome decoding step is proposed to find the optimized fuzzy-proportional-integral-derivative (fuzzy-PID) control parameters. Due to minimizing tracking error of the controller design criterion, the fitness function integral of square error (ISE) was employed to utilize the advantages of the modified GA. The proposed method was then applied to a novel autonomous hovercraft motion model to display the superiority to the standard GA.

In this paper, cuckoo search algorithm (CSA) is suggested for determining optimal operation parameters of the combined wind turbine and hydrothermal system (CWHTS) in order to minimize total fuel cost of all operating thermal power plants while all constraints of plants and system are exactly satisfied. In addition to CSA, Particle swarm optimization (PSO), PSO with constriction factor and inertia weight factor (FCIW-PSO) and social ski-driver (SSD) are also implemented for comparisons. The CWHTS is optimally scheduled over twenty-four one-hour interval and total cost of producing power energy is employed for comparison. Via numerical results and graphical results, it indicates CSA can reach much better results than other ones in terms of lower total cost, higher success rate and faster search process. Consequently, the conclusion is confirmed that CSA is a very efficient method for the problem of determining optimal operation parameters of CWHTS

Bài viết tập trung nghiên cứu, chế tạo hệ thống nhận diện vân tay ứng dụng hỗ trợ coi thi và điểm danh sinh viên. Xuất phát từ việc nghiên cứu cơ sở lý thuyết về sinh trắc học nhận dạng vân tay, từ đó tác giả xây dựng hệ thống quản lý và kiểm tra dựa trên đặc điểm các dấu vân tay của mỗi sinh viên.

The expected explosion of video traffic in 5G ultradense networks will pose many challenges to the Internet service providers, e.g., degraded capacity and unfair quality of service (QoS). The most efficient solution is resource allocation that does not require any network architecture changes. This article proposes a social-aware spectrum sharing and caching helper selection (SSC) strategy that exploits the resources of the mobile users (MUs), i.e., downlink spectrum resources for sharing and caching storage resources for multicasting, to offload the videos in dense deviceto- device (D2D) 5G networks. Particularly, we consider physical and social attributes of the MUs to formulate an SSC optimization problem. The SSC problem is solved to optimally control: which MUs, namely sharing mobile users (SUs), that share the downlink spectrum resources and which MUs, namely caching mobile helpers, that cache the requested videos for D2D multicast communications by reusing the shared downlink spectrum resources. The objective is to maximize the system capacity while satisfying the constraints on capacity fluctuation among the receiving mobile users (RUs) and target signal-to-interference-plus-noise ratio at the SUs, to guarantee the RUs and the SUs high QoS fairness. Simulation results are shown to demonstrate the benefits of the SSC strategy.

In the past few decades, dye-based contamination has been considered as a severe environmental problem faced by many developing countries due to increasingly growth of textile industry. Carbon-based materials have found as an excellent adsorbent for organic species because of its porous structure. Conversely, the cost-inefficiency and the difficulty to collect them after use, is the mainly negative mark when applying them in the large-scale. Thus, the development of low-cost, facile processing and ecofriendly membranes with high performance and high adsorption capacity for dye-based pollutants should be considered as a very important and urgent task. Herein, we wish to report the application of poly (vinyl alcohol)-based blend membranes combined with agar and maltodextrin for the elimination of crystal violet (CV) in water media. These blend membranes were fabricated via the simple solvent casting process. Effect of different factors, e.g., contact time between adsorbents and adsorbates, solution pH, and initial crystal violet concentration on the uptake capacity of blend membrane was studied in batch model. The obtained results revealed that adsorption kinetic was well obeyed with Pseudo-second order model, which was mainly controlled by chemisorption process. Langmuir model still well-described for adsorption isotherm for crystal violet dye of poly (vinyl alcohol) membrane combined with agar and maltodextrin. The maximum amount of CV uptake by blend membrane was found to be 84.618 mg g 1. These outcomes indicate a potential use of poly (vinyl alcohol)-based blend membranes combined with agar and maltodextrin for the elimination of CV in water media.

In this paper, we develop a new extended state variable observer based load frequency controller (LFC) scheme for three-area interconnected power systems. The extended state observerbased load frequency controllers are developed which utilize disturbance estimation techniques. The propose control approach assures that the fluctuating things of the load frequencies reaches to a safer range and the load frequencies can also be made at a very minimal not to have an effect on power quality and power flow in multi-area interconnected power system. The results of the simulations using MATLAB/SIMULINK done did not only address that the proposed newly control method works effectively but also change powerfully the parameter variations of the interconnected areas of the power system. Especially, it works very well to limit disturbances impact on interconnected areas in the system. Therefore, the performance of interconnected power system under different multi-conditions is simulated with the new control method to demonstrate the feasibility of the system.