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The livestock industry is one of the important sectors of agriculture in Vietnam. The swine-breeding farms are mainly spontaneous, the common wastewater is treated by biogas technology. However, the actual operation at the farms, shows that the wastewater treatment by biogas has been high content and still exceeded the standards of national regulation QCVN 62-MT:2016/BTNMT of COD, BOD5, TN, PO43-, leading to affect the environment. An empirical study was carried out to treat swine-breeding wastewater after biogas technology using Sagittaria sagittifolia and Enydra fluctuans. The results showed that the swine-breeding farming wastewater treatment model with Enydra fluctuans has an efficiency of 73.3% of COD content, 89.2% of BOD5, 88.3% of TN, and 89.6% of PO43-. Sagittaria sagittifolia showed a yield of 66.7% of COD content, 78.7% of BOD5, 69.5% of TN, and 85.1% of PO43-. With the same conditions and the same experimental design method, Enydra fluctuans showed better treatment results than Sagittaria sagittifolia. However, wastewater is treated by Sagittaria sagittifolia and Enydra fluctuans meeting the regulations QCVN 62-MT:2016/BTNMT, column B for pH, COD, BOD5, TN, PO43- parameters after 30 days. The treatmen model shows great potential for using aquatic plants to remove pollutants from swine-breeding wastewater. However, further studies should be carried out to evaluate the model's stability and applicability in practice.

This paper aims to investigate the nonlinear buckling and post-buckling of eccentrically oblique stiffened sandwich functionally graded double curved shallow shells resting on elastic foundations in thermal environment. The shells are reinforced by functionally graded eccentrically oblique stiffeners with deviation angles. Two types of sandwich functionally graded double curved shallow shells with the differences of distribution of functionally graded face sheets and homogeneous core are considered. Material properties of the sandwich shells and stiffeners are assumed to vary continuously and smoothly in the thickness direction according to Sigmoid power law. The formula of force and moment resultants and the nonlinear equilibrium equations are established based on the improved Donnell theory and Lekhnitskii's smeared stiffeners technique. The analytical displacement solutions are chosen based on the trigonometric forms satisfying the boundary conditions. The value of critical buckling loads and the load – deflection curves of the shells are obtained by using the Bubnov – Galerkin method. In numerical results; effect of geometrical parameters, elastic foundations, temperature increment, compressive load and oblique stiffeners on the critical buckling loads and post-buckling load – deflection curves of the shells are studied specifically. The obtained results are also compared with others from literature to validate the accuracy of the present method and approach.

This work presents the nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by single-walled carbon nanotubes resting on elastic foundations based on the higher order shear deformation theory with geometrical nonlinearity in von Karman–Donnell sense. The composite shells are made of various amorphous polymer matrices: poly(methyl methacrylate) (PMMA) and poly{(m-phenylenevinylene)-co-[(2,5-dioctoxy-p-phenylene) vinylene]} (PmPV). The governing equations are solved by the Galerkin method and Airy's stress function to achieve mechanical and thermal post-buckling behaviors of nanocomposite double-curved shallow shells. Various types of distributions of carbon nanotubes, both uniform distributions, and functionally graded distributions are examined. The material properties of nanocomposite double-curved shallow shells are assumed to be temperature dependent. Detailed parametric studies are carried out on the effect of various types of distribution and volume fractions of carbon nanotubes, temperature increments, elastic foundations, edge to radius and edge to thickness ratios on the nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by CNTs.

Based on Reddy's third order shear deformation shell theory and Galerkin method, this paper introduces analytical solutions to study nonlinear buckling behaviors of imperfect carbon nanotube reinforced composite cylindrical panels on elastic foundations in thermal environments. The panels are reinforced by single-walled carbon nanotubes and the eccentrically longitudinal and transversal stiffeners. The effects of geometrical parameters, eccentrically stiffeners, elastic foundations, initial imperfection, temperature increment and nanotube volume fraction on the mechanical behaviors of the nanocomposite cylindrical panels are also examined in numerical results. Some comparisons with results of other authors show the accuracy of the present theory and approach.

Предложена схема водоснабжения с сопутствующими магистральным трубопроводам линиями с меньшим диаметром труб для решения задачи оптимального потокораспределения в крупных городах Вьетнама. В результате гидравлического расчета предложенной схемы водоснабжения стабилизировано потокораспределение и подача воды потребителям при необходимом давлении, в т.ч. и при аварии на сети. Актуальность задачи в том, что в крупных городах сложилась серьезная проблема с обеспечением населения и промышленных предприятий доброкачественной питьевой водой в необходимом количестве и с достаточным напором. Хаотичная застройка отдельных районов городов привела к образованию достаточно сложной системы водоснабжения, состоящей из магистральных трубопроводов большого сечения и множества тупиковых участков. Из-за недостаточного напора воды в водопроводной сети большинство потребителей вынуждены устанавливать индивидуальные резервуары и емкости на крышах зданий. Неравномерный отбор воды из сети и ее нерациональное использование нарушают гидравлический режим подачи и распределения воды, а также влияют на ее качество.

Few epidemiologic surveys have been performed to assess the prevalence of diabetes in representative samples, and few data are available on the epidemiologic features of diabetes in Southeast Asia. We report the results of a 1990 study performed in the Hanoi area (Vietnam) on 4,912 subjects (95.0% of the eligible population), aged 15 years or over, selected by a stratified random cluster procedure using the 1989 census list. A two-step design was used: 1) screening for diabetes by measuring capillary blood glucose (CBG) before dinner with a Glucometer II device; and 2) for subjects with a CBG measurement ofor = 105 mg/dl, a diagnostic test on the following morning, using a 75-g oral glucose tolerance test and World Health Organization criteria (93.9% of the positive screenees took this test). CBG values before dinner were unimodally distributed and skewed to the right, increasing with age in both sexes. Women had a significantly higher level of age-adjusted CBG than did men before dinner (p0.0001) as well as when fasting (p0.0001) and 2 hours after the oral glucose tolerance test (p = 0.013). The prevalence of diabetes was 1.2% (95% confidence interval (CI) 0.9-1.5) and of impaired glucose tolerance, 1.6% (95% CI 1.3-2.0). Women had a significantly higher age-adjusted prevalence of diabetes than did men (relative risk = 2.3; 95% CI 1.3-4.1). Of the 63 diabetic subjects, nine (14.3%) had been diagnosed before the study, only one was obviously insulin dependent, and only one was obese with a body mass index ofor = 27 kg/m2. The subjects living in the urban areas had higher levels of fasting and 2-hour CBG and a higher diabetes prevalence than did the rural inhabitants (relative risk = 1.3; 95% CI 1.04-3.23). Diabetes appears to be a rare disease in the Hanoi area (1.4% for subjects aged 30-64 years, after age standardization using the Segi distribution), affecting women two times as often as men. Typical insulin-dependent (type I) or obese non-insulin-dependent (type II) diabetes mellitus patients are uncommon.