Tùng Nguyễn - Academia.edu (original) (raw)

Papers by Tùng Nguyễn

Materials Research Express

The nanoparticles of bentonite can be easily synthesized by hydrothermal treatment with microwave... more The nanoparticles of bentonite can be easily synthesized by hydrothermal treatment with microwave-assisted method. The products were characterized by XRD, FTIR, BET, SEM, EDS, and DLS. Results have revealed that the nano-bentonite was in nanometer scale with particles size of 200–300 nm. The SEM analysis of the nano-bentonite dispersion showed that a decrease in agglomeration and surface roughness. The nano-bentonite possessed high surface area (152.4 m2.g−1) and pore volume (0.25 cm3.g−1). Additionally, nanocomposite hydrogels (NB/PAA) were synthesized through the free-radical polymerization of acrylic acid (PAA) in the presence of the as-synthesized nano-bentonite (NB). The presence of NB in hydrogel matrix may improve the tensile strength of hydrogel. The tensile strength of the hydrogel increases from 0.294 to 1.609 MPa when NB content was 1.0% (NB10/PAA). Under the optimum conditions, the nanocomposite hydrogels (NB10/PAA) exhibited high water absorption capacity of 420.0 g w a...

IOP Conference Series: Earth and Environmental Science

Plastic microbeads are commonly used in many personal care products and can cause adverse impacts... more Plastic microbeads are commonly used in many personal care products and can cause adverse impacts to the environment and ecosystem. The toxicological problem with these pollutants are due to their non-biodegradable materials, which washed down the drain; end up accumulating in the aquatic system causing increased frequency and quantity of items ingested by biota. Several polymers (e.g. Polyethylene) especially those found in plastic microbeads have been reported to be in tandem with other toxic contaminants serving as a vector for their transports in the environment. Thus, the legislative ban for plastic microbeads is used in some developed countries, but many countries including Vietnam do not take any legal action. This present study aimed at potential microbead’s existence in the cosmetic market of Ho Chi Minh City (HCMC). The list and ingredients of microbeads containing personal care products (toothpaste, facial cleanser/scrubs and body wash/scrubs) have been checked. The micro...

Ministry of Science and Technology, Vietnam

The objective of this work was to study the effects of different plasticisers [glycerol (G), prop... more The objective of this work was to study the effects of different plasticisers [glycerol (G), propylene glycol (PG), polyethylene glycol 400 (PEG 400)] at different contents (10-30% compared to hydroxypropyl methylcellulose (HPMC)) on the properties of HPMC/shellac composite films. Sensory, mechanical properties, and surface morphology were used to evaluate changes in the composite films by adding different plasticisers. The results showed that with the addition of plasticisers, the films became more transparent and flexible. As the plasticiser content increased, the tensile strength and elastic modulus of the films decreased. At a plasticiser content of 20%, the water vapor permeability (WVP) of the composite films reached its minimum value. The SEM images showed that the HPMC/shellac composite film containing 20% G had the smoothest surface, and the components of this film were uniformly distributed.

Journal of Risk and Financial Management

Harry Markowitz introduced the Modern Portfolio Theory (MPT) for the first time in 1952 which has... more Harry Markowitz introduced the Modern Portfolio Theory (MPT) for the first time in 1952 which has been applied widely for optimal portfolio selection until now. However, the theory still has some limitations that come from the instability of covariance matrix input. This leads the selected portfolio from MPT model to change the status continuously and to suffer the high cost of transaction. The traditional estimator of the covariance matrix has not solved this limitation yet, especially when the dimensionality of the portfolio soars. Therefore, in this paper, we conduct a practical discussion on the feasible application of the shrinkage estimator of the covariance matrix, which is expected to encourage the investors focusing on the shrinkage–based framework for their portfolio selection. The empirical study on the Vietnam stock market in the period of 2011–2021 shows that the shrinkage approach has much better performance than other traditional methods on the primary portfolio evalu...

Advances in Engineering Research and Application, 2022

Journal of Asian Finance, Economics and Business, 2021

Stepping into the technological boom time, Vietnam has integrated into the trends of using Fintec... more Stepping into the technological boom time, Vietnam has integrated into the trends of using Fintech applications as a new means of payment. This article evaluates the relationship between perceived security (including service security and platform security), knowledge, confirmation, perceived usefulness, satisfaction, attitude and lastly enterprise’s images regarding the service and continuous intention to use Fintech services. The survey results of 352 Vietnamese customers using Fintech services, reliability test and extended post-acceptance model (EPAM) which is based on PAM and ECT models. From the survey, we further found out that perceived security (BSS) has no direct impact on continued intention to use, while perceived security (BSS) has positive impact on confirmation (CON), similarly, perceived usefulness (PU) and user’s satisfaction (SES). Knowledge of the Mobile Fintech payment service (KNOW) has a positive impact on perceived security (BSS). Confirmation (CON) has a posit...

2020 5th International Conference on Green Technology and Sustainable Development (GTSD), 2020

It is very necessary to build a tool for critical diagnosis of heart disease related to human hea... more It is very necessary to build a tool for critical diagnosis of heart disease related to human health. In this paper, a state-of-art method with multi-class support vector machine is proposed to classify types of heart disease in different scenarios of heartbeat datasets. In practice, electrocardiogram signals are preprocessed using a median filter to obtain smooth electrocardiogram signals and then the smooth electrocardiogram signals are segmented to obtain heartbeats. A short-time Fourier transform algorithm is applied on heartbeats to produce frequency information, which can be seen as features of heart disease. Therefore, the features are the input of the multi-class support vector machine classifier for training and testing. In addition, the electrocardiogram signals are collected from the MIT-BIH database for this research, in which there are five types of heart disease with two cases of intra-and inter-patient. The experimental results show that the high accuracy is obtained ...

Journal of Composites Science, 2021

To evaluate the effects of surface modification with stearic acid on the dispersion of some inorg... more To evaluate the effects of surface modification with stearic acid on the dispersion of some inorganic fillers in polyethylene (PE) matrix, masterbatches containing 20–40 wt% of stearic acid uncoated and coated inorganic fillers and the linear low-density polyethylene (LLDPE) films containing 3–7% stearic acid uncoated and coated inorganic fillers were prepared. Two types of inorganic fillers used in the masterbatch included bentonite and silica. The structural change of inorganic fillers, whose surface was modified with stearic acid, was studied using IR spectroscopy. The dispersion of inorganic fillers in LLDPE matrix was evaluated using scanning electron microscope (masterbatch samples) and optical microscope (film samples). Changes in the melting temperature of LLDPE in the presence of inorganic fillers were evaluated by using differential scanning calorimeter (DSC). The mechanical properties of the films were evaluated according to ASTM D882. Surface-treated fillers with stearic...

Optics Letters, 2021

Microsphere biolasers have attracted a great deal of interest due to their potential for biosensi... more Microsphere biolasers have attracted a great deal of interest due to their potential for biosensing and cell tracking. Here we demonstrate a novel, to the best of our knowledge, microfluidic-based fabrication of nearly monodisperse dye-doped protein microsphere biolasers with a tunable size from 150 to 50 µm. In particular, for an 85 µm-bead, about 70% of the fabricated microspheres have the same size of 85 µm. Under optical pumping, the fabricated microspheres emit whispering gallery mode lasing emission with a lasing threshold of 7 µ J m m − 2 and quality ( Q ) factor up to 3000. Interestingly, microspheres with the same size exhibit a similar lasing threshold and spectrum. The result indicates a high reproducibility of microsphere biolasers by the microfluidic-based fabrication technique. This Letter provides an effective method for mass production of high- Q factor microsphere biolasers which is a significant step toward real biosensing and medical applications.

Aquaculture Research, 2021

2017 International Conference on Advanced Technologies for Communications (ATC), 2017

In this paper, we propose efficient Zero-Forcing (ZF) Detectors based on the a Group Detection (G... more In this paper, we propose efficient Zero-Forcing (ZF) Detectors based on the a Group Detection (GD) approach in order to reduce the computational cost of the conventional linear detectors when they are adopted in Massive MIMO systems. Using the GD, we first divide a Massive MIMO system into two MIMO ones with smaller dimensions. Then, we apply the conventional ZF detector to the sub-systems to recover the signals. The resulting detector is called ZF-GD. In order to further improve the But Error Rate (BER) performance of the receiver, we propose the second detector, called ZF-IGD, by applying the conventional ZF detector to the sub-systems in an iterative manner. Both analytical and simulation results are provided to illustrate the performance and complexity of the proposed detectors. It is shown that they are suitable for Massive MIMO systems and can be used flexibly depending on the compromise between performance improvement and computational complexity.

Journal of Membrane Science, 2021

Abstract Microporous membrane has shown great potential for the separation of carbon dioxide from... more Abstract Microporous membrane has shown great potential for the separation of carbon dioxide from the gas mixture. Beside the membrane performance, the membrane preparation method is a factor to be concerned in this technique. In this work, pure silica DDR zeolite membranes on silica porous substrate were synthesized from an economical and environmentally efficient process. Porous silica substrate was fabricated using a low cost material. The membrane growth reaction used a minimum amount of chemical, produced no waste generation. Part of the reactant is supplied from porous substrate. The membrane quality is strongly dependent on the exposed faces of seed crystals and the pH value of the template solution. The obtained membranes show very high permeance and selectivity for CO2 from a CO2/CH4 gas mixture in both dry and humid conditions and hot gas flow. The membrane maintains stability in high performance with the separation factor of 440–500 for a test period of one week.

REV Journal on Electronics and Communications, 2018

In Multiple Input Multiple Output (MIMO) systems, the complexities of detectors depend on the siz... more In Multiple Input Multiple Output (MIMO) systems, the complexities of detectors depend on the size of the channel matrix. In Massive MIMO systems, detection complexity becomes remarkably higher because the dimensions of the channel matrix get much larger. In order to recover the signals in the up-link of a Massive MIMO system at reduced complexities, we first divide the system into two sub-systems. After that, we apply the Minimum Mean Square Error (MMSE) and Bell Laboratory Layer Space Time (BLAST) detectors to each subsystem, resulting in the so-called MMSE-GD and BLAST-GD detectors, respectively. To further enhance the BER performance of Massive MIMO systems under the high-load conditions, we propose two additional detectors, called MMSE-IGD and BLAST-IGD by respectively applying the conventional MMSE and BLAST on the sub-systems in an iterative manner. It is shown via computer simulation and analytical results that the proposed detectors enable the system to achieve not only hig...

TELKOMNIKA (Telecommunication Computing Electronics and Control), 2020

Electrocardiogram signal is the electrical actvity of the heart and doctors can diagnose heart di... more Electrocardiogram signal is the electrical actvity of the heart and doctors can diagnose heart disease based on this electrocardiogram signal. However, the electrocardiogram signals often have noise and artifact components. Therefore, one electrocardiogram signal without the noise and artifact plays an important role in heart disease diagnosis with more accurate results. This paper proposes a wavelet transform with three stages of decomposition, filter, and reconstruction for eliminating the noise and artifact in the electrocardiogram signal. The signal after decomposing produces approximation and detail coefficients, which contains the frequency ranges of the noise and artifact components. Hence, the approximation and detail coefficients with the frequency ranges corresponding to the noise and artifact in the electrocardiogram signal are eliminated by filters before they are reconstructed. For the evaluation of the proposed algorithm, filter evaluation metrics are applied, in which signal-to-noise ratio and mean squared error along with power spectral density are employed. The simulation results show that the proposed wavelet algorithm at level 8 is effective, in which the with the "dmey" wavelet function was selected be the best based power spectrum density.

IOP Conference Series: Earth and Environmental Science, 2019

Air pollution is a serious problem in Vietnam, especially in urban areas with high pressures of p... more Air pollution is a serious problem in Vietnam, especially in urban areas with high pressures of population, traffic, construction, and industrial development. Besides high accurate measurements from automatic and continuous monitoring ground stations and high-cost sensor devices, low-cost sensors have recently utilized to extent air pollution monitoring networks although their data quality is still argumentative. In this paper, we present a low-cost device, named FAirKit, which measured 6 basic air pollutants including PM2.5, PM10, CO, O3, NO2, and SO2, and temperature and relative humidity. The sensors are calibrated with standard devices to improve their data quality. FAirKits are installed and transferred data in real-time to servers where an information system based on Sensor Web Enablement (SWE) standard of Open Geospatial Consortium (OGC) has been developed to store, process, and visualize real-time air pollution information. Currently, the low-cost sensors network has been deploying in Hanoi, Vietnam to enhance public awareness and alert local people to air pollution.

International journal of surgery case reports, Jan 21, 2018

Left-sided gallbladder without situs viscerum inversus (LSG-woSVI) is defined as a gallbladder lo... more Left-sided gallbladder without situs viscerum inversus (LSG-woSVI) is defined as a gallbladder located under the left lobe of the liver; to the left of the round/falciform ligament, but with all other viscera maintaining normal anatomical relationships. This is a rare congenital anomaly with a reported prevalence that ranges from 0.04% to 1.1%. It is usually an incidental intraoperative finding, and can be associated with anatomic abnormalities of the biliary tree, portal system and vasculature. LSG and associated variations may present significant challenges even for experienced surgeon. LSG-woSVI was unexpectedly discovered in a 49-year-old, Vietnamese female during laparoscopic cholecystectomy. There were no pre-operative indications of sinistroposition. The cystic duct joined the common hepatic duct on the right side, and the cystic artery crossed anterior to the common bile duct in a right-to-left direction. Antegrade cholecystectomy was performed without intraoperative or post...

Environment, Development and Sustainability, 2016

Vietnam is prone to tropical storms. Climate change effects contribute to sea level rise, floods,... more Vietnam is prone to tropical storms. Climate change effects contribute to sea level rise, floods, progression of the low water line and coastal erosion. This paper inventories the perception of local people, assesses and values main aspects of the livelihood damage caused by the tropical storms of the period 2008-2013 in three coastal communes of the Ky Anh District of the Ha Tinh Province in Central Vietnam. The communes were selected because the location of their coastal line is perpendicular to the storm itself, which made them prone to damage. The effects of increasingly extreme weather conditions on three communities in an area most affected by storms and floods on the local residents and their responses to these changing environmental conditions are analyzed and assessed. The results of questionnaires completed by randomly selected local inhabitants of these communes show that storms and related hazards such as flood, sea level rise and heavy rain are perceived as the most impacting climate change intensified phenomena on agriculture and aquaculture, livestock, household property and income. Opinions and measured data provided by the commune and district authorities allow estimating the total direct cost of the tropical storm at 1.56 million US(TheusedconversionrateVND/US (The used conversion rate VND/US(TheusedconversionrateVND/US is 21,730 when the research was conducted in 2014) during the period 2008-2013. The long-term costs of adaptation and social impact measures will be significantly higher. Details of the monetary figures allow identifying the physical and natural capital of the area as being most affected by the storm. Trend and cost analysis show that the total financial support for hazard prevention and management during & Thinh An Nguyen

2014 International Conference on Advanced Technologies for Communications (ATC 2014), 2014

A High-rate Spatial Modulation (HR-SM) scheme, whose maximum spectral efficiency is in proportion... more A High-rate Spatial Modulation (HR-SM) scheme, whose maximum spectral efficiency is in proportional to the number of transmit antennas nT, was proposed in [1]. However, the complexity of its maximum likelihood detector grows exponentially with nT, making it impractical as nT increases. Based on the codeword structure of the HR-SM scheme and on the conventional successive-interference-cancellation (SIC) detectors, this paper proposes low-complexity suboptimal detectors for the HR-SM scheme. These detectors can feasibly be utilized in the HR-SM scheme with large number of transmit antennas and high-order QAM/PSK modulations. In addition, simulation results and complexity analysis are presented to verify performances and complexities of the proposed decoders.

Proceedings of the 5th international workshop on Multimedia for cooking & eating activities - CEA '13, 2013

Automatically detecting food's taste is a non-trivial part. However, we realize that the taste of... more Automatically detecting food's taste is a non-trivial part. However, we realize that the taste of food can be extracted by directly analyzing recipes by the ingredients and the amount of them in the recipes. In this paper, we present a food analysis system to discover the taste of foods and to better understand the featured ingredients in each specific geographical region. The main features of this system are (1) to extract dominant ingredients and tastes in a region by analyzing the ingredients' frequency and its uniqueness, and (2) to transform user's existing materials or original recipe to a new recipe according to a targeted taste. To examine the feasibility and applicability of the algorithm, we have developed a web-based application with a recipe database collected from approximately 200 recipes in over 7 regions of Japan:

Materials Research Express

The nanoparticles of bentonite can be easily synthesized by hydrothermal treatment with microwave... more The nanoparticles of bentonite can be easily synthesized by hydrothermal treatment with microwave-assisted method. The products were characterized by XRD, FTIR, BET, SEM, EDS, and DLS. Results have revealed that the nano-bentonite was in nanometer scale with particles size of 200–300 nm. The SEM analysis of the nano-bentonite dispersion showed that a decrease in agglomeration and surface roughness. The nano-bentonite possessed high surface area (152.4 m2.g−1) and pore volume (0.25 cm3.g−1). Additionally, nanocomposite hydrogels (NB/PAA) were synthesized through the free-radical polymerization of acrylic acid (PAA) in the presence of the as-synthesized nano-bentonite (NB). The presence of NB in hydrogel matrix may improve the tensile strength of hydrogel. The tensile strength of the hydrogel increases from 0.294 to 1.609 MPa when NB content was 1.0% (NB10/PAA). Under the optimum conditions, the nanocomposite hydrogels (NB10/PAA) exhibited high water absorption capacity of 420.0 g w a...

IOP Conference Series: Earth and Environmental Science

Plastic microbeads are commonly used in many personal care products and can cause adverse impacts... more Plastic microbeads are commonly used in many personal care products and can cause adverse impacts to the environment and ecosystem. The toxicological problem with these pollutants are due to their non-biodegradable materials, which washed down the drain; end up accumulating in the aquatic system causing increased frequency and quantity of items ingested by biota. Several polymers (e.g. Polyethylene) especially those found in plastic microbeads have been reported to be in tandem with other toxic contaminants serving as a vector for their transports in the environment. Thus, the legislative ban for plastic microbeads is used in some developed countries, but many countries including Vietnam do not take any legal action. This present study aimed at potential microbead’s existence in the cosmetic market of Ho Chi Minh City (HCMC). The list and ingredients of microbeads containing personal care products (toothpaste, facial cleanser/scrubs and body wash/scrubs) have been checked. The micro...

Ministry of Science and Technology, Vietnam

The objective of this work was to study the effects of different plasticisers [glycerol (G), prop... more The objective of this work was to study the effects of different plasticisers [glycerol (G), propylene glycol (PG), polyethylene glycol 400 (PEG 400)] at different contents (10-30% compared to hydroxypropyl methylcellulose (HPMC)) on the properties of HPMC/shellac composite films. Sensory, mechanical properties, and surface morphology were used to evaluate changes in the composite films by adding different plasticisers. The results showed that with the addition of plasticisers, the films became more transparent and flexible. As the plasticiser content increased, the tensile strength and elastic modulus of the films decreased. At a plasticiser content of 20%, the water vapor permeability (WVP) of the composite films reached its minimum value. The SEM images showed that the HPMC/shellac composite film containing 20% G had the smoothest surface, and the components of this film were uniformly distributed.

Journal of Risk and Financial Management

Harry Markowitz introduced the Modern Portfolio Theory (MPT) for the first time in 1952 which has... more Harry Markowitz introduced the Modern Portfolio Theory (MPT) for the first time in 1952 which has been applied widely for optimal portfolio selection until now. However, the theory still has some limitations that come from the instability of covariance matrix input. This leads the selected portfolio from MPT model to change the status continuously and to suffer the high cost of transaction. The traditional estimator of the covariance matrix has not solved this limitation yet, especially when the dimensionality of the portfolio soars. Therefore, in this paper, we conduct a practical discussion on the feasible application of the shrinkage estimator of the covariance matrix, which is expected to encourage the investors focusing on the shrinkage–based framework for their portfolio selection. The empirical study on the Vietnam stock market in the period of 2011–2021 shows that the shrinkage approach has much better performance than other traditional methods on the primary portfolio evalu...

Advances in Engineering Research and Application, 2022

Journal of Asian Finance, Economics and Business, 2021

Stepping into the technological boom time, Vietnam has integrated into the trends of using Fintec... more Stepping into the technological boom time, Vietnam has integrated into the trends of using Fintech applications as a new means of payment. This article evaluates the relationship between perceived security (including service security and platform security), knowledge, confirmation, perceived usefulness, satisfaction, attitude and lastly enterprise’s images regarding the service and continuous intention to use Fintech services. The survey results of 352 Vietnamese customers using Fintech services, reliability test and extended post-acceptance model (EPAM) which is based on PAM and ECT models. From the survey, we further found out that perceived security (BSS) has no direct impact on continued intention to use, while perceived security (BSS) has positive impact on confirmation (CON), similarly, perceived usefulness (PU) and user’s satisfaction (SES). Knowledge of the Mobile Fintech payment service (KNOW) has a positive impact on perceived security (BSS). Confirmation (CON) has a posit...

2020 5th International Conference on Green Technology and Sustainable Development (GTSD), 2020

It is very necessary to build a tool for critical diagnosis of heart disease related to human hea... more It is very necessary to build a tool for critical diagnosis of heart disease related to human health. In this paper, a state-of-art method with multi-class support vector machine is proposed to classify types of heart disease in different scenarios of heartbeat datasets. In practice, electrocardiogram signals are preprocessed using a median filter to obtain smooth electrocardiogram signals and then the smooth electrocardiogram signals are segmented to obtain heartbeats. A short-time Fourier transform algorithm is applied on heartbeats to produce frequency information, which can be seen as features of heart disease. Therefore, the features are the input of the multi-class support vector machine classifier for training and testing. In addition, the electrocardiogram signals are collected from the MIT-BIH database for this research, in which there are five types of heart disease with two cases of intra-and inter-patient. The experimental results show that the high accuracy is obtained ...

Journal of Composites Science, 2021

To evaluate the effects of surface modification with stearic acid on the dispersion of some inorg... more To evaluate the effects of surface modification with stearic acid on the dispersion of some inorganic fillers in polyethylene (PE) matrix, masterbatches containing 20–40 wt% of stearic acid uncoated and coated inorganic fillers and the linear low-density polyethylene (LLDPE) films containing 3–7% stearic acid uncoated and coated inorganic fillers were prepared. Two types of inorganic fillers used in the masterbatch included bentonite and silica. The structural change of inorganic fillers, whose surface was modified with stearic acid, was studied using IR spectroscopy. The dispersion of inorganic fillers in LLDPE matrix was evaluated using scanning electron microscope (masterbatch samples) and optical microscope (film samples). Changes in the melting temperature of LLDPE in the presence of inorganic fillers were evaluated by using differential scanning calorimeter (DSC). The mechanical properties of the films were evaluated according to ASTM D882. Surface-treated fillers with stearic...

Optics Letters, 2021

Microsphere biolasers have attracted a great deal of interest due to their potential for biosensi... more Microsphere biolasers have attracted a great deal of interest due to their potential for biosensing and cell tracking. Here we demonstrate a novel, to the best of our knowledge, microfluidic-based fabrication of nearly monodisperse dye-doped protein microsphere biolasers with a tunable size from 150 to 50 µm. In particular, for an 85 µm-bead, about 70% of the fabricated microspheres have the same size of 85 µm. Under optical pumping, the fabricated microspheres emit whispering gallery mode lasing emission with a lasing threshold of 7 µ J m m − 2 and quality ( Q ) factor up to 3000. Interestingly, microspheres with the same size exhibit a similar lasing threshold and spectrum. The result indicates a high reproducibility of microsphere biolasers by the microfluidic-based fabrication technique. This Letter provides an effective method for mass production of high- Q factor microsphere biolasers which is a significant step toward real biosensing and medical applications.

Aquaculture Research, 2021

2017 International Conference on Advanced Technologies for Communications (ATC), 2017

In this paper, we propose efficient Zero-Forcing (ZF) Detectors based on the a Group Detection (G... more In this paper, we propose efficient Zero-Forcing (ZF) Detectors based on the a Group Detection (GD) approach in order to reduce the computational cost of the conventional linear detectors when they are adopted in Massive MIMO systems. Using the GD, we first divide a Massive MIMO system into two MIMO ones with smaller dimensions. Then, we apply the conventional ZF detector to the sub-systems to recover the signals. The resulting detector is called ZF-GD. In order to further improve the But Error Rate (BER) performance of the receiver, we propose the second detector, called ZF-IGD, by applying the conventional ZF detector to the sub-systems in an iterative manner. Both analytical and simulation results are provided to illustrate the performance and complexity of the proposed detectors. It is shown that they are suitable for Massive MIMO systems and can be used flexibly depending on the compromise between performance improvement and computational complexity.

Journal of Membrane Science, 2021

Abstract Microporous membrane has shown great potential for the separation of carbon dioxide from... more Abstract Microporous membrane has shown great potential for the separation of carbon dioxide from the gas mixture. Beside the membrane performance, the membrane preparation method is a factor to be concerned in this technique. In this work, pure silica DDR zeolite membranes on silica porous substrate were synthesized from an economical and environmentally efficient process. Porous silica substrate was fabricated using a low cost material. The membrane growth reaction used a minimum amount of chemical, produced no waste generation. Part of the reactant is supplied from porous substrate. The membrane quality is strongly dependent on the exposed faces of seed crystals and the pH value of the template solution. The obtained membranes show very high permeance and selectivity for CO2 from a CO2/CH4 gas mixture in both dry and humid conditions and hot gas flow. The membrane maintains stability in high performance with the separation factor of 440–500 for a test period of one week.

REV Journal on Electronics and Communications, 2018

In Multiple Input Multiple Output (MIMO) systems, the complexities of detectors depend on the siz... more In Multiple Input Multiple Output (MIMO) systems, the complexities of detectors depend on the size of the channel matrix. In Massive MIMO systems, detection complexity becomes remarkably higher because the dimensions of the channel matrix get much larger. In order to recover the signals in the up-link of a Massive MIMO system at reduced complexities, we first divide the system into two sub-systems. After that, we apply the Minimum Mean Square Error (MMSE) and Bell Laboratory Layer Space Time (BLAST) detectors to each subsystem, resulting in the so-called MMSE-GD and BLAST-GD detectors, respectively. To further enhance the BER performance of Massive MIMO systems under the high-load conditions, we propose two additional detectors, called MMSE-IGD and BLAST-IGD by respectively applying the conventional MMSE and BLAST on the sub-systems in an iterative manner. It is shown via computer simulation and analytical results that the proposed detectors enable the system to achieve not only hig...

TELKOMNIKA (Telecommunication Computing Electronics and Control), 2020

Electrocardiogram signal is the electrical actvity of the heart and doctors can diagnose heart di... more Electrocardiogram signal is the electrical actvity of the heart and doctors can diagnose heart disease based on this electrocardiogram signal. However, the electrocardiogram signals often have noise and artifact components. Therefore, one electrocardiogram signal without the noise and artifact plays an important role in heart disease diagnosis with more accurate results. This paper proposes a wavelet transform with three stages of decomposition, filter, and reconstruction for eliminating the noise and artifact in the electrocardiogram signal. The signal after decomposing produces approximation and detail coefficients, which contains the frequency ranges of the noise and artifact components. Hence, the approximation and detail coefficients with the frequency ranges corresponding to the noise and artifact in the electrocardiogram signal are eliminated by filters before they are reconstructed. For the evaluation of the proposed algorithm, filter evaluation metrics are applied, in which signal-to-noise ratio and mean squared error along with power spectral density are employed. The simulation results show that the proposed wavelet algorithm at level 8 is effective, in which the with the "dmey" wavelet function was selected be the best based power spectrum density.

IOP Conference Series: Earth and Environmental Science, 2019

Air pollution is a serious problem in Vietnam, especially in urban areas with high pressures of p... more Air pollution is a serious problem in Vietnam, especially in urban areas with high pressures of population, traffic, construction, and industrial development. Besides high accurate measurements from automatic and continuous monitoring ground stations and high-cost sensor devices, low-cost sensors have recently utilized to extent air pollution monitoring networks although their data quality is still argumentative. In this paper, we present a low-cost device, named FAirKit, which measured 6 basic air pollutants including PM2.5, PM10, CO, O3, NO2, and SO2, and temperature and relative humidity. The sensors are calibrated with standard devices to improve their data quality. FAirKits are installed and transferred data in real-time to servers where an information system based on Sensor Web Enablement (SWE) standard of Open Geospatial Consortium (OGC) has been developed to store, process, and visualize real-time air pollution information. Currently, the low-cost sensors network has been deploying in Hanoi, Vietnam to enhance public awareness and alert local people to air pollution.

International journal of surgery case reports, Jan 21, 2018

Left-sided gallbladder without situs viscerum inversus (LSG-woSVI) is defined as a gallbladder lo... more Left-sided gallbladder without situs viscerum inversus (LSG-woSVI) is defined as a gallbladder located under the left lobe of the liver; to the left of the round/falciform ligament, but with all other viscera maintaining normal anatomical relationships. This is a rare congenital anomaly with a reported prevalence that ranges from 0.04% to 1.1%. It is usually an incidental intraoperative finding, and can be associated with anatomic abnormalities of the biliary tree, portal system and vasculature. LSG and associated variations may present significant challenges even for experienced surgeon. LSG-woSVI was unexpectedly discovered in a 49-year-old, Vietnamese female during laparoscopic cholecystectomy. There were no pre-operative indications of sinistroposition. The cystic duct joined the common hepatic duct on the right side, and the cystic artery crossed anterior to the common bile duct in a right-to-left direction. Antegrade cholecystectomy was performed without intraoperative or post...

Environment, Development and Sustainability, 2016

Vietnam is prone to tropical storms. Climate change effects contribute to sea level rise, floods,... more Vietnam is prone to tropical storms. Climate change effects contribute to sea level rise, floods, progression of the low water line and coastal erosion. This paper inventories the perception of local people, assesses and values main aspects of the livelihood damage caused by the tropical storms of the period 2008-2013 in three coastal communes of the Ky Anh District of the Ha Tinh Province in Central Vietnam. The communes were selected because the location of their coastal line is perpendicular to the storm itself, which made them prone to damage. The effects of increasingly extreme weather conditions on three communities in an area most affected by storms and floods on the local residents and their responses to these changing environmental conditions are analyzed and assessed. The results of questionnaires completed by randomly selected local inhabitants of these communes show that storms and related hazards such as flood, sea level rise and heavy rain are perceived as the most impacting climate change intensified phenomena on agriculture and aquaculture, livestock, household property and income. Opinions and measured data provided by the commune and district authorities allow estimating the total direct cost of the tropical storm at 1.56 million US(TheusedconversionrateVND/US (The used conversion rate VND/US(TheusedconversionrateVND/US is 21,730 when the research was conducted in 2014) during the period 2008-2013. The long-term costs of adaptation and social impact measures will be significantly higher. Details of the monetary figures allow identifying the physical and natural capital of the area as being most affected by the storm. Trend and cost analysis show that the total financial support for hazard prevention and management during & Thinh An Nguyen

2014 International Conference on Advanced Technologies for Communications (ATC 2014), 2014

A High-rate Spatial Modulation (HR-SM) scheme, whose maximum spectral efficiency is in proportion... more A High-rate Spatial Modulation (HR-SM) scheme, whose maximum spectral efficiency is in proportional to the number of transmit antennas nT, was proposed in [1]. However, the complexity of its maximum likelihood detector grows exponentially with nT, making it impractical as nT increases. Based on the codeword structure of the HR-SM scheme and on the conventional successive-interference-cancellation (SIC) detectors, this paper proposes low-complexity suboptimal detectors for the HR-SM scheme. These detectors can feasibly be utilized in the HR-SM scheme with large number of transmit antennas and high-order QAM/PSK modulations. In addition, simulation results and complexity analysis are presented to verify performances and complexities of the proposed decoders.

Proceedings of the 5th international workshop on Multimedia for cooking & eating activities - CEA '13, 2013

Automatically detecting food's taste is a non-trivial part. However, we realize that the taste of... more Automatically detecting food's taste is a non-trivial part. However, we realize that the taste of food can be extracted by directly analyzing recipes by the ingredients and the amount of them in the recipes. In this paper, we present a food analysis system to discover the taste of foods and to better understand the featured ingredients in each specific geographical region. The main features of this system are (1) to extract dominant ingredients and tastes in a region by analyzing the ingredients' frequency and its uniqueness, and (2) to transform user's existing materials or original recipe to a new recipe according to a targeted taste. To examine the feasibility and applicability of the algorithm, we have developed a web-based application with a recipe database collected from approximately 200 recipes in over 7 regions of Japan: