International Journal of Thermal Sciences, Aug 1, 2011
This paper presents a comparison of experimental data and numerical predictions for the hydrodyna... more This paper presents a comparison of experimental data and numerical predictions for the hydrodynamic and thermal fields in a two-channel plate heat exchanger. The temperature distributions on the first and the last of the three plates, the friction factor and the Nusselt number for each channel as well as the outlet temperatures of the two streams are compared. The laminar model has satisfactorily been validated for Reynolds numbers less than 400. For the turbulent flow regime, several two-equation models were tested and the Realizable ke3 model with non-equilibrium wall functions has been found to give the closest results to the experimental data. The flow distribution in cross-sections of the channels was studied numerically. Streams of higher velocities on the channels' sides, where two narrow vertical smooth passages are located, were observed.
It is recognized that recycling and reuse of waste can result in significant savings in materials... more It is recognized that recycling and reuse of waste can result in significant savings in materials and energy. In this research, the adsorption of methyl blue (MB) using waste rice husk ash (Rha) and mesoporous silica materials made from Rha (R-MCM) were analyzed. Mesoporous silica materials were synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and Rha as the silica source. The prepared samples were characterized by Brunnaur-Emmet-Teller (BET) adsorption isotherm analyzer and transmission electron microscope (TEM) analysis. The results showed the surface area of R-MCM materials was 1347 m2g−1 and the pore volume was 0.906 cm3g−1. TEM analysis showed that the mesoporous materials generally exhibited ordered hexagonal arrays of mesopores with a uniform pore size. The effects on adsorption performance under different initial dye concentrations, different pH values and different dosages of adsorbent were also studied. Both Langmuir and Freundlich adsorpti...
International Journal of Thermal Sciences, Aug 1, 2004
... Workshop on Solar Ponds, Tunis, Tunisia, December 20, 2001, 5 p. [6] K Al-Jamal and S Khashan... more ... Workshop on Solar Ponds, Tunis, Tunisia, December 20, 2001, 5 p. [6] K Al-Jamal and S Khashan, Effect of energy extraction on solar pond performance. ... [20] R. Ben Mansour, CT Nguyen, N. Galanis, Transient heat and mass transfer of a salt-gradient solar pond, in: Proc. ...
A breakthrough biosorbent namely multi-metal binding biosorbent (MMBB) made from a combination of... more A breakthrough biosorbent namely multi-metal binding biosorbent (MMBB) made from a combination of tea wastes, maple leaves and mandarin peels, was prepared to evaluate their biosorptive potential for removal of Cd(II), Cu(II), Pb(II) and Zn(II) from multi-metal aqueous solutions. FTIR and SEM were conducted, before and after biosorption, to explore the intensity and position of the available functional groups and changes in adsorbent surface morphology. Carboxylic, hydroxyl and amine groups were found to be the principal functional groups for the sorption of metals. MMBB exhibited best performance at pH5.5 with maximum sorption capacities of 31.73, 41.06, 76.25 and 26.63mg/g for Cd(II), Cu(II), Pb(II) and Zn(II), respectively. Pseudo-first and pseudo-second-order models represented the kinetic experimental data in different initial metal concentrations very well. Among two-parameter adsorption isotherm models, the Langmuir equation gave a better fit of the equilibrium data. For Cu(I...
This paper presents an overview of physical (PHY) and medium access control (MAC) layers for IEEE... more This paper presents an overview of physical (PHY) and medium access control (MAC) layers for IEEE 802.11a, which is a standard of a broadband high-speed wireless local area network (WLAN). IEEE 802.11a uses 5 GHz frequency band and its PHY is based on orthogonal frequency division multiplexing (OFDM). In this paper, we evaluate the OFDMbased PHY and MAC performance of IEEE 802.11a under various practical wideband channel models, which are abstracted from actual propagation measurements. The effects of different transmission modes defined in PHY on the IEEE 802.11 system performance are investigated. We also discuss the impact of link adaptation, which attempts to choose the best-suited transmission mode according to channel conditions, on the overall system performance.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
The paper describes a pure neutron method for determining both Pu content and Pu isotopic composi... more The paper describes a pure neutron method for determining both Pu content and Pu isotopic composition of PuBe neutron sources by neutron coincidence technique, without using gamma-spectrometry. The new procedure based on the R/T-T relationship is a developed version of the R/T-method based on R/T-M Pu calibration curve described in [C.T. Nguyen, J. Bagi, L. Lakosi, A novel method of quantitative assay of PuBe neutron sources by neutron coincidence technique, Nucl. Instr. and Meth. B 246 (2006) 409], utilizing Pu isotopic correlations; here R, T, M Pu are double count rate, single count rate and total Pu content, respectively. Accuracy of the method was found to be about 2-3% and 15% for 239 Pu component and Pu content, respectively. Measurement time as a function of detector efficiency is treated in detail. It is shown that in a system of frame, a transuranium neutron source can be characterized by a pair of coordinates [R/T, T].
... nanofluids. In general, it was noticed that the mean Nusselt number increases with particle v... more ... nanofluids. In general, it was noticed that the mean Nusselt number increases with particle volume fraction and Reynolds number and decreases with an increase in disk spacing. ... insulated. An inlet tube of l of 4 cm is considered in all cases. ...
In this work, we study numerically the heat transfer and fluid flow inside a circular inclined tu... more In this work, we study numerically the heat transfer and fluid flow inside a circular inclined tube. The thermal boundary condition is that of a constant and uniform (axially and circumferentially) heat flux on the tube wall. A finite volume method is used to solve, in dimensionless form, the parabolic equations of mixed convection. The results, obtained for water with
A study of Taka-amylase A of conidia from Aspergillus oryzae RIB40 was done. During the research,... more A study of Taka-amylase A of conidia from Aspergillus oryzae RIB40 was done. During the research, proteins from conidia and germinated conidia were analyzed using SDS-PAGE, 2-D gel electrophoresis, Western blot analysis, MALDI-TOF Mass spectrometry, and native-PAGE combined with activity staining of TAA. The results showed that TAA exists not only in germinated conidia but also in conidia. Some bands representing degraded products of TAA were detected. Conidia, which formed on starch (SCYA), glucose (DCYA), and glycerol (GCYA) plates, contained mature TAA. Only one active band of TAA was detected after native-PAGE activity staining. In addition, TAA activity was detected in cell extracts of conidia using 0.5 M acetate buffer, pH 5.2, as extraction buffer, but was not detected in whole conidia or cell debris. The results indicate that TAA exists in conidia in active form even when starch, glucose, or glycerol is used as carbon source. TAA might belong to a set of basal proteins inside conidia, which helps in imbibition and germination of conidia.
In 2003, the authors conducted a population-based, cross-sectional survey to determine the preval... more In 2003, the authors conducted a population-based, cross-sectional survey to determine the prevalence of osteoporosis and related factors in Vietnamese adult women by using quantitative ultrasound at the heel bone (calcaneus). A total of 2,232 adult women aged 20 years, living in Hanoi City, and free of illnesses affecting bone metabolism were randomly selected to participate in the study. Subjects' bone mass was assessed by speed of sound at the calcaneus, referred to as quantitative ultrasound measurement. The T-score threshold, defined as ÿ1.8, was used to identify subjects with osteoporosis. The crude prevalence of osteoporosis in Hanoi City was 15.4%; after adjustment for age, it was 9.0%. Among premenopausal women, the crude prevalence of osteoporosis was higher in the urban areas compared with the rural areas. By contrast, postmenopausal women in the rural areas had a higher prevalence of osteoporosis. Multiple logistic regression analysis revealed that factors associated with low speed of sound were age, menopause, educational level, lifelong occupation, recreational weight-bearing exercise, number of births, and height. Results suggest that osteoporosis is a noteworthy problem in Vietnam, and intervention strategies should be considered to control it, especially in high-risk populations.
International Journal of Thermal Sciences, Aug 1, 2011
This paper presents a comparison of experimental data and numerical predictions for the hydrodyna... more This paper presents a comparison of experimental data and numerical predictions for the hydrodynamic and thermal fields in a two-channel plate heat exchanger. The temperature distributions on the first and the last of the three plates, the friction factor and the Nusselt number for each channel as well as the outlet temperatures of the two streams are compared. The laminar model has satisfactorily been validated for Reynolds numbers less than 400. For the turbulent flow regime, several two-equation models were tested and the Realizable ke3 model with non-equilibrium wall functions has been found to give the closest results to the experimental data. The flow distribution in cross-sections of the channels was studied numerically. Streams of higher velocities on the channels' sides, where two narrow vertical smooth passages are located, were observed.
It is recognized that recycling and reuse of waste can result in significant savings in materials... more It is recognized that recycling and reuse of waste can result in significant savings in materials and energy. In this research, the adsorption of methyl blue (MB) using waste rice husk ash (Rha) and mesoporous silica materials made from Rha (R-MCM) were analyzed. Mesoporous silica materials were synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and Rha as the silica source. The prepared samples were characterized by Brunnaur-Emmet-Teller (BET) adsorption isotherm analyzer and transmission electron microscope (TEM) analysis. The results showed the surface area of R-MCM materials was 1347 m2g−1 and the pore volume was 0.906 cm3g−1. TEM analysis showed that the mesoporous materials generally exhibited ordered hexagonal arrays of mesopores with a uniform pore size. The effects on adsorption performance under different initial dye concentrations, different pH values and different dosages of adsorbent were also studied. Both Langmuir and Freundlich adsorpti...
International Journal of Thermal Sciences, Aug 1, 2004
... Workshop on Solar Ponds, Tunis, Tunisia, December 20, 2001, 5 p. [6] K Al-Jamal and S Khashan... more ... Workshop on Solar Ponds, Tunis, Tunisia, December 20, 2001, 5 p. [6] K Al-Jamal and S Khashan, Effect of energy extraction on solar pond performance. ... [20] R. Ben Mansour, CT Nguyen, N. Galanis, Transient heat and mass transfer of a salt-gradient solar pond, in: Proc. ...
A breakthrough biosorbent namely multi-metal binding biosorbent (MMBB) made from a combination of... more A breakthrough biosorbent namely multi-metal binding biosorbent (MMBB) made from a combination of tea wastes, maple leaves and mandarin peels, was prepared to evaluate their biosorptive potential for removal of Cd(II), Cu(II), Pb(II) and Zn(II) from multi-metal aqueous solutions. FTIR and SEM were conducted, before and after biosorption, to explore the intensity and position of the available functional groups and changes in adsorbent surface morphology. Carboxylic, hydroxyl and amine groups were found to be the principal functional groups for the sorption of metals. MMBB exhibited best performance at pH5.5 with maximum sorption capacities of 31.73, 41.06, 76.25 and 26.63mg/g for Cd(II), Cu(II), Pb(II) and Zn(II), respectively. Pseudo-first and pseudo-second-order models represented the kinetic experimental data in different initial metal concentrations very well. Among two-parameter adsorption isotherm models, the Langmuir equation gave a better fit of the equilibrium data. For Cu(I...
This paper presents an overview of physical (PHY) and medium access control (MAC) layers for IEEE... more This paper presents an overview of physical (PHY) and medium access control (MAC) layers for IEEE 802.11a, which is a standard of a broadband high-speed wireless local area network (WLAN). IEEE 802.11a uses 5 GHz frequency band and its PHY is based on orthogonal frequency division multiplexing (OFDM). In this paper, we evaluate the OFDMbased PHY and MAC performance of IEEE 802.11a under various practical wideband channel models, which are abstracted from actual propagation measurements. The effects of different transmission modes defined in PHY on the IEEE 802.11 system performance are investigated. We also discuss the impact of link adaptation, which attempts to choose the best-suited transmission mode according to channel conditions, on the overall system performance.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
The paper describes a pure neutron method for determining both Pu content and Pu isotopic composi... more The paper describes a pure neutron method for determining both Pu content and Pu isotopic composition of PuBe neutron sources by neutron coincidence technique, without using gamma-spectrometry. The new procedure based on the R/T-T relationship is a developed version of the R/T-method based on R/T-M Pu calibration curve described in [C.T. Nguyen, J. Bagi, L. Lakosi, A novel method of quantitative assay of PuBe neutron sources by neutron coincidence technique, Nucl. Instr. and Meth. B 246 (2006) 409], utilizing Pu isotopic correlations; here R, T, M Pu are double count rate, single count rate and total Pu content, respectively. Accuracy of the method was found to be about 2-3% and 15% for 239 Pu component and Pu content, respectively. Measurement time as a function of detector efficiency is treated in detail. It is shown that in a system of frame, a transuranium neutron source can be characterized by a pair of coordinates [R/T, T].
... nanofluids. In general, it was noticed that the mean Nusselt number increases with particle v... more ... nanofluids. In general, it was noticed that the mean Nusselt number increases with particle volume fraction and Reynolds number and decreases with an increase in disk spacing. ... insulated. An inlet tube of l of 4 cm is considered in all cases. ...
In this work, we study numerically the heat transfer and fluid flow inside a circular inclined tu... more In this work, we study numerically the heat transfer and fluid flow inside a circular inclined tube. The thermal boundary condition is that of a constant and uniform (axially and circumferentially) heat flux on the tube wall. A finite volume method is used to solve, in dimensionless form, the parabolic equations of mixed convection. The results, obtained for water with
A study of Taka-amylase A of conidia from Aspergillus oryzae RIB40 was done. During the research,... more A study of Taka-amylase A of conidia from Aspergillus oryzae RIB40 was done. During the research, proteins from conidia and germinated conidia were analyzed using SDS-PAGE, 2-D gel electrophoresis, Western blot analysis, MALDI-TOF Mass spectrometry, and native-PAGE combined with activity staining of TAA. The results showed that TAA exists not only in germinated conidia but also in conidia. Some bands representing degraded products of TAA were detected. Conidia, which formed on starch (SCYA), glucose (DCYA), and glycerol (GCYA) plates, contained mature TAA. Only one active band of TAA was detected after native-PAGE activity staining. In addition, TAA activity was detected in cell extracts of conidia using 0.5 M acetate buffer, pH 5.2, as extraction buffer, but was not detected in whole conidia or cell debris. The results indicate that TAA exists in conidia in active form even when starch, glucose, or glycerol is used as carbon source. TAA might belong to a set of basal proteins inside conidia, which helps in imbibition and germination of conidia.
In 2003, the authors conducted a population-based, cross-sectional survey to determine the preval... more In 2003, the authors conducted a population-based, cross-sectional survey to determine the prevalence of osteoporosis and related factors in Vietnamese adult women by using quantitative ultrasound at the heel bone (calcaneus). A total of 2,232 adult women aged 20 years, living in Hanoi City, and free of illnesses affecting bone metabolism were randomly selected to participate in the study. Subjects' bone mass was assessed by speed of sound at the calcaneus, referred to as quantitative ultrasound measurement. The T-score threshold, defined as ÿ1.8, was used to identify subjects with osteoporosis. The crude prevalence of osteoporosis in Hanoi City was 15.4%; after adjustment for age, it was 9.0%. Among premenopausal women, the crude prevalence of osteoporosis was higher in the urban areas compared with the rural areas. By contrast, postmenopausal women in the rural areas had a higher prevalence of osteoporosis. Multiple logistic regression analysis revealed that factors associated with low speed of sound were age, menopause, educational level, lifelong occupation, recreational weight-bearing exercise, number of births, and height. Results suggest that osteoporosis is a noteworthy problem in Vietnam, and intervention strategies should be considered to control it, especially in high-risk populations.
Uploads
Papers by cong nguyen