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Publication

AUGMENTATION OF SOLAR WATER DISTILLER PERFORMANCE WITH PV/T

( 2020)

Nguyen Viet Linh Le

;

Tri Hieu Le

;

Thi Minh Hao Dong

;

Van Vang Le

;

Dinh Tung

Recently, due to global warming and urbanization, there are many major cities that may face the challenge of day zero next decades. Obviously, water is an indispensable component for maintaining life on the earth. Although portable water is required of the hour, the quantity of available freshwater is impacted significantly by sea-level rise and pollution from industrialization. As a consequence of the global water crisis, different methods for clean water production from brackish water have been studied and developed in practice, however, the solar distillation of water is the most economical and desirable approach due to this method utilize solar energy that is the environmentally friendly and economical resource. Over the last 15 years, the impressive price drop of the photovoltaic solar collector (PV/T) makes them popular and easy to access. As a result, the employment of PV/T in solar stills is emerging as a potential device for water distillation. Therefore, in this paper, an active solar distiller combined with a photovoltaic panel has been reviewed for improvement of the distillate yield and effectiveness of solar photovoltaic. This review work presents a variety of studies on various types of solar still (for example conventional solar still (CSS), double slope solar still (DSSS), stepped solar distiller, and cascade solar still) couples with different solar water collectors (such as flat plate collector (FPC) and evacuated tubes collector (ETC)) and solar photovoltaic modules. It is obtained that the hybrid PV/T active solar still improves the distillate yield, energy efficiency, and exergy efficiency as compared to passive mode. The cooling method enhances the performance of the photovoltaic solar collector as well as the productivity of solar still. Moreover, the environmental economic estimation reveals that the solar still coupled with the PV/T mitigated considerably the amount of CO2. It can be stated that it is suitable to commercialize the hybrid PV/T active solar still for supplying not only electricity but drinking water also. Finally, this review paper also suggests the scope for the research in the future.

Publication

Automatic fuzzy genetic algorithm in clustering for images based on the extracted intervals

( 2020)

Dinh Phamtoan

;

Tai Vovan

This research proposes the method to extract the characteristics of images to become the intervals. These intervals are used to build the automatic fuzzy genetic algorithm for images (AFGI). In the proposed model, the overlap measure is the criterion to evaluate the closeness of intervals, and the new Davies and Bouldin index is the objective function. The AFGI can determine the proper number of clusters, the images in each cluster, and the probability to belong to clusters of images at the same time. The experiments with different types of images illustrate the steps of AFGI, and show its significant benefit in comparing to other algorithms.

Publication

OCR error correction using correction patterns and self-organizing migrating algorithm

( 2020)

Quoc-Dung Nguyen

;

Duc-Anh Le

;

Nguyet-Minh Phan

;

Ivan Zelinka

Optical character recognition (OCR) systems help to digitize paper-based historical achieves. However, poor quality of scanned documents and limitations of text recognition techniques result in different kinds of errors in OCR outputs. Postprocessing is an essential step in improving the output quality of OCR systems by detecting and cleaning the errors. In this paper, we present an automatic model consisting of both error detection and error correction phases for OCR post-processing. We propose a novel approach of OCR post-processing error correction using correction pattern edits and evolutionary algorithm which has been mainly used for solving optimization problems. Our model adopts a variant of the self-organizing migrating algorithm along with a fitness function based on modifications of important linguistic features. We illustrate how to construct the table of correction pattern edits involving all types of edit operations and being directly learned from the training dataset. Through efficient settings of the algorithm parameters, our model can be performed with high-quality candidate generation and error correction. The experimental results show that our proposed approach outperforms various baseline approaches as evaluated on the benchmark dataset of ICDAR 2017 Post-OCR text correction competition

Publication

An In Depth Analysis of Ocr Errors for Unconstrained Vietnamese Handwriting

( 2020)

Nguyễn Quốc Dũng

OCR post-processing is an essential step to improve the accuracy of OCR-generated texts by detecting and correcting OCR errors. In this paper, the OCR texts are resulted from an OCR engine which is based on the attention-based encoder-decoder model for unconstrained Vietnamese handwriting. We identify various kinds of Vietnamese OCR errors and their possible causes. Detailed statistics of Vietnamese OCR errors are provided and analyzed at both character level and syllable level, using typical OCR error characteristics such as error rate, error mapping/edit, frequency and error length. Furthermore, the statistical analyses are done on training and test sets of a benchmark database to infer whether the test set is the appropriate representative of the training set regarding the OCR error characteristics. We also discuss the choice of designing OCR post-processing approaches at character level or at syllable level relying on provided statistics of studied datasets.

Publication

Optimal solutions for fixed head short-term hydrothermal system scheduling problem

( 2020)

Thanh Long Duong

;

Van-Duc Phan

;

Thuan Thanh Nguyen

;

Thang Trung Nguyen

In this paper, optimal short-term hydrothermal operation (STHTO) problem is determined by a proposed high-performance particle swarm optimization (HPPSO). Control variables of the problem are regarded as an optimal solution including reservoir volumes of hydropower plants (HdPs) and power generation of thermal power plants (ThPs) with respect to scheduled time periods. This problem focuses on reduction of electric power generation cost (EPGC) of ThPs and exact satisfactory of all constraints of HdPs, ThPs and power system. The proposed method is compared to earlier methods and other implemented methods such as particle swarm optimization (PSO), constriction factor (CF) and inertia weight factor (IWF)-based PSO (FCIW-PSO), two time-varying acceleration coefficient (TTVACs)-based PSO (TVAC-PSO), salp swarm algorithm (SSA), and Harris hawk algorithm (HHA). By comparing EPGC from 100 trial runs, speed of search and simulation time, the suggested HPPSO method sees it is more robust than other ones. Thus, HPPSO is recommended for applying to the considered and other problems in power systems.

Publication

Development of quantitative ion physic chemistry properties-activity relationship (QIPAR) and docking simulation for sars-covid-2 protein

( 2021)

Tat Pham Van

;

Quang Nguyen Minh

;

Thuy Bui Thi Phuong

;

Hoa Tran Thai

;

Duoc Nguyen Thanh

Currently, many drugs are being studied and potentially used in the treatment of SARS-CoV-2. Compounds studied are mostly organic substances. This work investigates the ability to inhibit SARS-CoV-2 of various 20 metal ions based on their ability to inhibit several biological systems; the physicochemical properties of metal ions were calculated by quantum chemistry DFT (B3LYP/ LanL2DZ) were used to develop the QIPAR hybrid models. Hybrid models QIPARGA-MLR (k = 4) and QIPARGA-ANN with architecture I(4)-HL(9)-O(1) were developed to predict the biological activity of metal ions. Metal ions were also investigated for their inhibitory potential for the protein SARS-CoV-2 (PDB6LU7) by docking simulation techniques. We predicted the binding sites of metal ions to the active sites of the SARS-CoV-2 protein (PDB6LU7). These studies are consistent with their activities against different biological systems. This research will also contribute to the development of metal oxide nanomaterials.

Publication

Modifications of Heat Transfer and Induced Flow Rate of a Solar Chimney by an Obstacle in the Air Channel

( 2021)

Y Quoc Nguyen

;

Trieu Nhat Huynh

;

Mai-Anh Ho Pham

Using renewable energy resources in buildings has been increasing for saving energy. Among widely used methods, solar chimneys absorb solar radiation and induce an airflow for ventilation, heating, or cooling buildings. The performance of a solar chimney depends on the heat transfer in its air channel, which can be modified by changing the shape of the heat exchange surface. In this study, we examine the effects of a rectangular obstacle placed on the heated surface of the air channel of a solar chimney. A numerical model was built with the Computational Fluid Dynamics (CFD) technique. By changing the geometries of the chimney and of the obstacle, and location of the obstacle, it was found that the obstacle had strong effects on the local flow and heat transfer properties close to the object, particularly the Nusselt number and the temperature field. However, average quantities of the whole air channel flow, such as the averaged Nusselt number and the induced flow rate, were modified insignificantly, except for the temperature rise through the chimney and the thermal efficiency. The change of the flow rate and the average Nusselt number was 5.0% while the temperature rises and the thermal efficiency was up to 13.0%. The height of the obstacle had more influence than the length. This study suggests more investigations to achieve the objective of enhancing the induced flow rate for ventilation of buildings with an obstacle in the air channel of a solar chimney

Publication

Decoration of silver nanoparticles on nitrogen-doped nanoporous carbon derived from zeolitic imidazole framework-8 (ZIF-8) via in situ auto-reduction

( 2021)

Vediyappan Veeramani

;

Nguyen Van Chi

;

Yi-Lin Yang

;

Nguyen Thi Hong Huong

;

Thuan Van Tran

;

Tansir Ahamad

;

Saad M. Alshehri

;

Kevin C.-W. Wu

We discovered an in situ auto-reduction method to embed silver nanoparticles onto a nanoporous carbon (NC) derived from the zeolitic imidazole framework-8 (ZIF-8), without any requirement of the reducing agents. The detailed analysis demonstrated the formation of Ag NPs by the replacement of the metallic Zn residue in the NC with Ag ions. The synthesized Ag@NC exhibited a superior catalytic activity toward the reduction reaction of 4-nitrophenol into 4-aminophenol.

Publication

Highly Effective Degradation of Nitrophenols by Biometal Nanoparticles Synthesized using Caulis Spatholobi Extract

( 2021)

Van Thuan Le

;

Van-Cuong Nguyen

;

Xuan-Thang Cao

;

Tan Phat Chau

;

Thi Dung Nguyen

;

Thi Lan-Huong Nguyen

;

Van-Dat Doan

;

Hassan Karimi-Maleh

The green biosynthesis of metal nanoparticles (MNPs) has been proved to have many advantages over other methods due to its simplicity, large-scale production, ecofriendly approach, and high catalytic efficiency. This work describes a single-step technique for green synthesis of colloidal silver (AgNPs) and gold nanoparticles (AuNPs) using the extract from Caulis Spatholobi stems. Ultraviolet-visible spectroscopy measurements were used to optimize the main synthesis factors, including metal ion concentration, reaction time, and reaction temperature via surface plasmon resonance phenomenon. Fourier-transform infrared spectroscopy showed the possible functional groups responsible for reducing and stabilizing the synthesized MNPs. The powder X-ray diffraction and selected area electron diffraction analysis confirmed the crystalline nature of the biosynthesized MNPs. High-resolution transmission electron microscopy revealed the spherical shape of MNPs with an average size of 10-20 nm. The obtained MNPs also exhibited the enhanced catalytic activity in the reduction of 2-nitrophenol and 3-nitrophenol.

Publication

Load Frequency Control for Multi-Area Power Plants with Integrated Wind Resources

( 2021)

Van Van Huynh

;

Bui Le Ngoc Minh

;

Emmanuel Nduka Amaefule

;

Anh-Tuan Tran

;

Phong Thanh Tran

;

Van-Duc Phan

;

Viet-Thanh Pham

;

Tam Minh Nguyen

To provide a more practical method of controlling the frequency and tie-line power flow of a multi-area interconnected power system (MAIPS), a state observer based on sliding mode control (SOboSMC) acting under a second-order time derivative is proposed. The proposed design is used to study load frequency control against load disturbance, matched and mismatched uncertainty and parameter measurement difficulties of power systems that exist in the modern power plant, such as multi-area systems integrated with wind plants. Firstly, the state observer is designed to optimally estimate system state variables. The estimated states are applied to construct the model of the MAIPS. Secondly, a SOboSMC is designed with an integral switching surface acting on the second-order time derivative to forcefully drive the dynamic errors to zero and eliminate chattering, which can occur in the first-order approach to sliding mode control. In addition, the stability of the total power system is demonstrated with the Lyapunov stability theory based on a new linear matrix inequality (LMI) technique. To extend the validation of the proposed design control for practical purposes, it was tested in a New England system with 39 bus power against random load disturbances. The simulation results confirm the superiority of the proposed SOboSMC over other recent controllers with respect to overshoot and settling time.

Publication

Minimize electricity generation cost for large scale wind- thermal systems considering prohibited operating zone and power reserve constraints

( 2021)

Phan Nguyen Vinh

;

Bach Hoang Dinh

;

Van-Duc Phan

;

Hung Duc Nguyen

;

Thang Trung Nguyen

Wind power plants (WPs) play a very important role in the power systems because thermal power plants (TPs) suffers from shortcomings of expensive cost and limited fossil fuels. As compared to other renewable energies, WPs are more effective because it can produce electricity all a day from the morning to the evening. Consequently, this paper integrates the optimal power generation of TPs and WPs to absolutely exploit the energy from WPs and reduce the total electricity generation cost of TPs. The target can be reached by employing a proposed method, called one evaluation-based cuckoo search algorithm (OEB-CSA), which is developed from cuckoo search algorithm (CSA). In addition, conventional particle swarm optimization (PSO) is also implemented for comparison. Two test systems with thirty TPs considering prohibited working zone and power reserve constraints are employed. The first system has one wind power plant (WP) while the second one has two WPs. The result comparisons indicate that OEB-CSA can be the best method for the combined systems with WPs and TPs.

Publication

A Study of Physical Layer Security in SWIPT-Based Decode-and-Forward Relay Networks with Dynamic Power Splitting

( 2021)

Van-Duc Phan

;

Tan N. Nguyen

;

Anh Vu Le

;

Miroslav Voznak

In this paper, we study the physical layer security for simultaneous wireless information and power transfer (SWIPT)-based half-duplex (HD) decode-and-forward relaying system. We consider a system model including one transmitter that tries to transmit information to one receiver under the help of multiple relay users and in the presence of one eavesdropper that attempts to overhear the confidential information. More specifically, to investigate the secrecy performance, we derive closed-form expressions of outage probability (OP) and secrecy outage probability for dynamic power splitting-based relaying (DPSBR) and static power splitting-based relaying (SPSBR) schemes. Moreover, the lower bound of secrecy outage probability is obtained when the source’s transmit power goes to infinity. The Monte Carlo simulations are given to corroborate the correctness of our mathematical analysis. It is observed from simulation results that the proposed DPSBR scheme outperforms the SPSBR-based schemes in terms of OP and SOP under the impact of different parameters on system performance.

Publication

Novel recommendation for enhancing optical properties of CP-WLEDs by Ba2Si5N8Eu2+ phosphor

( 2021)

Van-Duc Phan

;

Minh Tran

;

Q. S. Vu

In this paper, the Ba2Si5N8Eu2+ phosphor is proposed as the novel recommendation for enhancing the optical properties in terms of D-CCT, CRI, CQS, and LO of the CP-WLEDs. Firstly, we conducted the physical model of the CP-WLEDs in the Light Tools software with the main parameters like the real LEDs. Furthermore, the scattering process in LEDs compound of the CP-WLEDs is simulated and investigated by the Matlab software. Then the influence of the Ba2Si5N8Eu2+ concentration on the D-CCT, CRI, CQS, and LO of the CP-WLEDs is investigated. Finally, the research results showed that the Ba2Si5N8Eu2+ concentration has a considerable effect on the D-CCT, CRI, CQS, and LO of the CP-WLEDs. From the results, we can state that the Ba2Si5N8Eu2+ phosphor can be considered as the novel recommendation for enhancing the optical properties of the CP-WLEDs.

Publication

Prediction of flow field in a solar chimney using ANFIS technique

( 2021)

Minh-Thu T Huynh

;

Tri Q Truong

;

Thinh N Doan

;

Trieu N Huynh

;

Tung V Nguyen

;

Viet T Nguyen

;

Y Q Nguyen

Solar chimneys have been intensively studied as an effective method for natural ventilation of buildings. Though numerical methods, such as Computational Fluid Dynamics (CFD), have been widely utilized in such studies, they usually require extensive computational resources. Moreover, experimental study is quite complicated and costly. In recent years, machine learning has started to be used as a tool in the thermal-fluid field. In this study, in order to save time and cost, Adaptive Neuro-Fuzzy Inference System (ANFIS) technique, a class of adaptive networks that incorporate both neural networks and fuzzy logic principles, is combined with CFD. A simulation model was first validated by experiment from another study in the field. The result was documented as a dataset using CFD code ANSYS Fluent (Academic version 2020 R2). Then, they are used to train and validate the ANFIS model. In particular, the study is to predict the fluid flow field in a 2-dimensional typical solar chimney when heat flux changes in the range of 400 to 1000 W/m2. Inputs of the ANFIS model are position and heat flux, while outputs are temperature and velocity at that location. As a result, the 2 ANFIS models could achieve R2 values of 0.997, 0.97 (training set) and 0.994, 0.9715 (testing set); RMSE are 1.009, 0.00224 (training set) and 1.074, 0.0204 (testing set) for outputs of temperature and velocity, respectively. Those results are acceptable. By using the ANFIS model, large amounts of flow fields with different scenarios can be estimated simultaneously. Therefore, it is expected that engineers and architects can have a quick tool in the process of design

Publication

Performance of a solar chimney configuration to achieve equal flow rate for ventilation of three-story building

( 2021)

T V Nguyen

;

Y Quoc Nguyen

In energy-efficient buildings, natural ventilation using solar chimneys greatly reduces energy consumption. In this study, a solar chimney was installed in a three-story building to examine the flow rate of the floors while balancing the flow rate of each floor. To predict the flow rate, a fluid dynamics model was developed based on a computational fluid dynamics (CFD) method with a calculated model of RNG k-e, heat flux 600 𝑊/𝑚2 . By changing design parameters, the air flow was investigated.

Publication

Influence of outlet/inlet area ratio on performance of a vertical solar chimney for natural ventilation of buildings

( 2021)

Y Q Nguyen

;

T N Huynh

In this study, effects of the contractions of the inlet and outlet areas of a vertical solar chimney were examined with a Computational Fluid Dynamics. The results show that the flow rate decreased with both the inlet and outlet areas. The outlet area influenced more than the inlet area did. The flow rate decreased linearly with the outlet area, however, was affected significantly only when the inlet area was below half of the air gap.

Publication

Multidisciplinary design optimization for sustainable design using building information modeling

( 2021)

Le Hung Tien

;

Nguyen Van Tung

This paper illustrates the application of computational design using Rhinoceros software and Grasshopper plugin to investigate a real accommodation with respect to the solar radiation reduction. The paper also introduces the basic concepts of Building Information Modelling (BIM) utilization in construction. The multidisciplinary BIM model show that the Computable BIM Model can be used for Architecture, Structure, Mechanical – Electrical – Plumbing (MEP) to help architects, designers do sustainable design such as acoustic comfort, lighting design on effective cost manner with many rapid design options from the conceptual design phase, to facilitate wind load simulation, predict structural behaviour under fierce conditions, to estimate heat load, HVAC systems performance for energy saving and sustainable design.

Publication

Software development for sustainable design in Vietnam: Ecosystem - An approach

( 2021)

Le Hung Tien

The needs for accurate energy consumption estimation in different design alternatives are essential for all projects. The demands to achieve sustainable design drive not only the efforts of a large number of researchers and organizations all over the world but also for designers in Vietnam, especially for building design in Vietnam, whereas the green constructions are growing rapidly. The developed software in the first stage helps the designers to quickly calculate and select the alternatives for green building design. This paper is carried out under the collaboration project between Van Lang University (VLU, Vietnam) and Carnegie Mellon University (CMU, USA) to develop a software for sustainable design, which focuses on energy consumption optimization. This software is the first project towards the full software development life cycle for green design in Vietnam.

Publication

Interval forecasting model for time series based on the fuzzy clustering technique

( 2021)

T Vovan

;

D Phamtoan

This paper proposes the forecasting model for the fuzzy time series based on the improvement of the background data and fuzzy relationship (IFTC). This algorithm is built based on the fuzzy cluster analysis which the suitable number of clusters for series is considered. The problem of interpolating data according to fuzzy relationships of time series in the trapezoidal fuzzy number is also established. The proposed model is illustrated step by step by a numerical example and effectively implemented by the Matlab procedure. The IFCT has advantages in comparing to other models via the several indexes such as the MAE, MAPE and MSE with the Enrollment dataset.

Publication

Flavones from Combretum quadrangulare Growing in Vietnam and Their Alpha-Glucosidase Inhibitory Activity

( 2021)

Thi-Bich-Ngoc Dao

;

Truong-Minh-Tri Nguyen

;

Van-Quy Nguyen

;

Thi-Minh-Dinh Tran

;

Nguyen-Minh-An Tran

;

Chuong Hoang Nguyen

;

Thi-Hoai-Thu Nguyen

;

Huu-Hung Nguyen

;

Jirapast Sichaem

;

Cong-Luan Tran

;

Thuc-Huy Duong

Combretum quadrangulare Kurz is widely used in folk medicine in Eastern Asia and is associated with various ethnopharmacological properties including hepatoprotective, antipyretic, analgesic, antidysenteric, and anthelmintic activities. Previous phytochemical investigations reported the presence of numerous triterpenes (mostly cycloartanes, ursanes, lupanes, and oleananes) along with dozens of flavonoids. However, the extracts of C. quadrangulare and isolated flavonoids have not been evaluated for their alpha-glucosidase inhibition. In the frame of our efforts dedicated to the chemical investigation of Vietnamese medicinal plants and their biological activities, a phytochemical study of the MeOH extract of the leaves of C. quadrangulare using bioactive guided isolation was undertaken. In this paper, the isolation and structure elucidation of twelve known compounds, 5-hydroxy-3,7,4′-trimethoxyflavone (1), ayanin (2), kumatakenin (3), rhamnocitrin (4), ombuin (5), myricetin-3,7,3′,5′-tetramethyl ether (6), gardenin D (7), luteolin (12), apigenin (13), mearnsetin (14), isoorientin (15), and vitexin (16) were reported. Bromination was applied to compounds 2 and 3 to provide four new synthetic analogues 8–11. All isolated and synthesized compounds were evaluated for alpha-glucosidase inhibition and antibacterial activity. Compounds 4 and 5 showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus while others were inactive. All compounds failed to reveal any activity toward extended spectrum beta-lactamase-producing Escherichia coli. Compounds 2, 4, 6–9, and 11–14 showed good alpha-glucosidase inhibition with IC50 values in the range of 30.5–282.0 µM. The kinetic of enzyme inhibition showed that 8 and 11 were noncompetitive type inhibition against alpha-glucosidase. In silico molecular docking model indicated that compounds 8 and 11 were potential inhibitors against enzyme α-glucosidase.

Journal Articles - Engineering Technology - 2021

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