Vietnam Academy of Science and Technology: Journals Online
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An enhanced genetic algorithm based courses timetabling method for maximal enrollments using maximum matching on bipartite graphs
Get PDFUniversities usually use academic credit systems for holding all training courses. They have to establish a suitable timetable for enrollment by students at beginning of every semester. This timetable must be met to all hard constraints and it is satisfied to soft constraints as high as possible. In some universities, students can enroll to the established timetable so that among of their courses is as much as possible. This leads to finish their studying program earlier than normally cases. In addition, this also leads to well-utilized resources such as facilities, teachers and so forth in universities. However, a timetable usually has so many courses and some its courses have same subjects but different time-slots. These may cause difficulties for manually enrolling by students. It may be fall into conflict of time when choosing two courses at same time-slots. It is difficult for enrollment with high satisfied. In this paper, we design a genetic algorithm based method for university timetable with maximal enrollments by using maximum matching on bipartite graph
CHARACTERIZATION AND ADSORPTION CAPACITY OF AMINE-SIO2 MATERIAL FOR NITRATE AND PHOSPHATE REMOVAL
Get PDFAmine-SiO2 material was synthesized and applied as a novel adsorbent for nitrate and phosphate removal from aqueous solution. The characterization of Amine-SiO2 were done by using TGA, FTIR, BET, and SEM analyses. Results showed that Amine-SiO2 had higher nitrate and phosphate adsorption capacity of 1.14 and 4.16 times, respectively, than commercial anion exchange resin (Akualite A420). In addition, Amine-SiO2 also had good durability with stable performance after at least 10 regeneration times, indicating that this material is very promising for commercialization in the future as an adsorbent for water treatment
A study on the relationship between gas-geochemical field and tectonic fault activities in the rivermouth area of northwestern Gulf of Tonkin
Get PDFThe article mentions the results of the new analysis of gas-geochemical and high resolution shallow seismic data acquired by the sea surveys in 2016, which revealed a remarkable coincidence between the seabed gas anomalies at river mouth area of Gulf of Tonkin and the gas distortion/accumulation phenomena in the near-surface sediment layers, especially right above the large tectonic fault systems, such as Red river, Lo river and Chay river. The gas-geochemical analysis reveals the existences of thermogenic and metamorphic methane and carbon dioxide gases within the faults of Red river and on Cat Ba island, anomalies of helium and hydrogen as well as the “heavy” isotopic carbon signals of methane and carbon dioxide in the areas of near-surface active faults. These new results suggest the initial conclusions about the relationship between gas-geochemical field and tectonic fault activities in study area
Homogenization of very rough three-dimensional interfaces for the poroelasticity theory with Biot's model
No full textIn this paper, we carry out the homogenization of a very rough three-dimensional interface separating two dissimilar generally anisotropic poroelastic solids modeled by the Biot theory. The very rough interface is assumed to be a cylindrical surface that rapidly oscillates between two parallel planes, and the motion is time-harmonic. Using the homogenization method with the matrix formulation of the poroelasicity theory, the explicit homogenized equations have been derived. Since the obtained homogenized equations are totally explicit, they are very convenient for solving various practical problems. As an example proving this, the reflection and transmission of SH waves at a very rough interface of tooth-comb type is considered. The closed-form analytical expressions of the reflection and transmission coefficients have been derived. Based on them, the effect of the incident angle and some material parameters on the reflection and transmission coefficients are examined numerically
RETRACTED: Manufacturing and evaluation of elastic properties of glass fiber reinforced polymers material
No full textVJMech’s Editors have decided to retract this article because it duplicates significant parts of papers that had previously published in other journals. The authors have misconduct concerning plagiarism of papers without citation.We really apologies to readers of the journal that this was not detected during the submission and review process
Utilization of Schizochytrium mangrovei PQ6 as feed for rotifer Brachionus plicatilis in rearing black sleeper’s larvae (Bostrichthys sinensis, Lacepede, 1881)
Get PDF Schizochytrium mangrovei PQ6 contains many important polyunsaturated fatty acids, such as docosahexaenoic acid (DHA, C22: 6w-3), eicosahexaenoic acid (EPA, C20: 5w-3) and docosapentaenoic acid (DPA, C22: 5w-6). These fatty acids are essential for survival and growth of many marine fish larvae. In this paper, fresh biomass of S. mangrovei PQ6 was used for culturing rotifer Brachionus plicatilis. In the first formula (L1), rotifers were fed on baker’s yeast; in second formula (L2), rotifers were fed on mixed two microalgae, Nannochloropsis oculata and Chaetoceros gracilis; in the third formula (L3), rotifers were fed on S. mangrovei PQ6 biomass. The results indicated that S. mangrovei PQ6 biomass can replace baker’s yeast and autotrophic microalgae in feeding rotifers. Total lipid, total fatty acid and polyunsaturated fatty acid contents of rotifers fed on formula 3 (S. mangrovei PQ6) were higher than those within others. High polyunsaturated fatty acid (C ≥ 20) in omega-3 and 6 groups; DHA and DPA contents of rotifers fed on S. mangrovei PQ6 were the highest, accounting for 39.81% of total fatty acid; 41.95% and 8.24% polyunsaturated fatty acids, corresponding to 20.52; 12.15 and 2.4 mg/g of dried weight, respectively.The survival rate of black sleeper’s larvae was highest when they were fed on rotifers grown on L3 formula (51.20 ± 0.89%), followed by L2 formula (48.70 ± 2.67%) and the lowest with L1 formula (43.44 ± 1.54%) (P 0.05). However, among three formulas, no significant difference was found in the growth of black sleeper’s larvae (P 0.05). These results suggest that biomass of S. mangrovei PQ6 can replace traditional feed like autotrophic microalgae or baker’s yeast for biomass culture of the Brachionus plicatilis rotifer for rearing black sleeper’s larvae to enhance seed quality to meet demands of market.
Safety assessment and the effect of squalene isolated from schizochytrium mangrovei pq6 on serum hdl - cholesterol levels in animal models
Get PDFIn this paper, the acute and subchronic toxicity and the effect of squalene isolated from heterotrophic marine microalga Schizochytrium mangrovei PQ6 on the serum levels of HDL-C were investigated using animal models. The results of acute toxicity study showed that by oral administration of the squalene on albino mice at the highest dose of 58.25 g/kg of whole body of mice/day, the LD50 was not determined. Squalene at doses of 400 mg and 1,200 mg/kg/day for 60 consecutive days have allowed the normal behavior, body weight, hematological and biochemical parameters, liver and kidney functions, morphology of liver, kidney and spleen, total plasma cholesterol content, however, HDL-C level was higher in squalene treated mices compared to control group (p 0.05). In addition, at doses of 600 and 1,200 mg/kg/day for 60 continuous days, squalene treated mice showed the increase in HDL-C level and HDL-C/total cholesterol ratio and the decrease in the contents of LDL-C and VLDL-C without affecting the body and liver weights and levels of total cholesterol and triglyceride.
Studies on the disinfection efficiency of hoa sen medical instrument sterilizing equipment at the general, obstetrics and paediatrics hospitals in TraVinh Province
Get PDFThis research aims to study on the disinfection efficiency of Hoa Sen medical instrument sterilizing equipment based on the application of ECA technology at General Hospital and Obstetrics and Paediatrics Hospitals in Tra Vinh. Disinfection using ECA technology is a method that does not require the introduction of special oxidizing agents except of water and salt. ECA solution - Anolyte solution has very strong oxidants, which oxidize components such as protein, lipid, etc. (usually of the bacterial cell membrane) that make the cell membrane decomposed, reducing 77−93% of the respiratory ability of bacterial cells, weakening them and eventually being destroyed. Hoa Sen medical instrument sterilizing equipment has a similar construction form as a regular double washing table with two wash basins, wherein one sink with a faucet which produces purified water, while other one has a faucet that gives anolyte solution for sterilization. Both faucets are based on a touch support. At the bottom of the sink an anolyte solution production system was installed. Valorization of the disinfection ability of the Hoa Sen medical instrument sterilizing equipment was based on the determination of the number of microorganisms on the surface of the instrument before and after being soaked with an antiseptic washing table. Microbiological criteria are the number of aerobic bacteria, E. Coli and Coliforms. Analytical samples were quantified by culture method on agar plates. Analysis of total aerobic bacteria, E. Coli and Coliforms bacteria according to Vietnam Standard TCVN 4884:2015, TCVN 6846:2007 and TCVN 6848:2007, respectively. The results showed that bacterial removal efficiency was elevated with a novel Hoa Sen sterilizing equipment anolyte. In laboratory scale, E. Coli and Coliforms bacteria with a density of 105 CFU/mL were completely removed in 30 sec contact with an anolyte solution of 300 mg/L active chlorine concentration. In hospital scale, the removal efficiency of total aerobic bacteria on the surface of medical instruments after surgery was 99% for one minute disinfection time. For E. Coli and Coliforms bacteria, the results of the analysis were not detected in both cases before and after sterilization.
ĐẶC ĐIỂM FRONT NHIỆT MẶT BIỂN VÙNG BIỂN ĐÔNG NAM VIỆT NAM
No full textThis paper presents an investigation of sea surface temperature front in the Southeast region of Vietnam using daily NOAA satellite images in April (dry season) and September (rainy season) for a period from 1985 to 2009. The method of Cayula and Cornilon (1992) for detecting the thermal front from satellite images was applied to evaluate the characteristics of the sea surface temperature front in the study area. The main features in front distribution, seasonal variations were described, and the relationship between front locations and fresh water discharge from Mekong river was qualitatively analyzed.Dựa trên nguồn dữ liệuảnh vệ tinh của NOAA trung bình ngàycủa các tháng 4(mùa kiệt) và các tháng 9 (mùa lũ) trong khoảng thời gian 25 năm (từ năm 1985 - 2009), bài báo này trình bày một nghiên cứucơ bản ứng dụng phương pháp xác định front nhiệt mặt biển từ ảnh vệ tinh (Cayula Cornillon, 1992) để đánh giá đặc điểm frontnhiệt mặt biển vùng Đông Nam Việt Nam. Các đặc trưng phân bố của front theo mùacũng như theo năm đã được phân tích và đánh giá định tính trong mối tương quanvới các trường khí tượng - hải văn cũng như với đặc trưng lưu lượng nước của hệthống sông Mê Kông
TIDAL ASYMMETRY IN MANGROVE FOREST - CASE STUDY IN SOUTHERN VIETNAM
No full textThe study aims to analyse the tidal asymmetry in mangrove forest by using the numerical modelling and the measured data in two mangrove forest areas: Can Gio (Ho Chi Minh city) and Cu Lao Dung (Soc Trang province). The results of 2D model in the mangrove forest show that there is the asymmetry in current velocity: Two velocity peaks exist at flood tide and two at ebb tide. The current velocity is the sum of the tidal flows from the channel and from the tidal exchange between the creek and the swamp. The calculated velocity depends strongly on drag force, which is due to the mangrove vegetation. Furthermore, the results from analysing the measured data in February 2012 in Can Gio, Ho Chi Minh city and in Sept–October 2014 in Cu Lao Dung (Soc Trang) also prove the existence of the tidal asymmetry: The current velocity in the mangrove at flood tide is more dominant than velocity at ebb tide. The water level also has the asymmetry, changes in the tidal cycles but does not get so dominant as the velocity does