The influence of service solutions on longitudinal and circumferential tensile properties of glass-polyester composite pipes

Traditionally used metals and alloys as constructive materials in process equipment can nowadays be successfully replaced in many cases by non-metallic composite materials. The influence of service solutions on the state of stress and tensile properties in longitudinal and circumferential direction of glass-polyester pipes is studied in this paper. These analyses are of great importance for the use of examined pipes in chemical industry. The pipes were produced by Corporation “Poliester” Priboj. The influence of two solutions, methanol and ammonia, was studied. The samples were treated in solutions for three, seven and ten days. After that, the samples were subjected to tensile testing by the standard procedure. The stresses and strengths were determined in longitudinal direction (testing on flat test specimens) and in circumferential direction (ring test). The analysis of test results, according to the type of solution and period of exposure, was done in comparison with the results obtained by virgin pipes testing (without the influence of the solution). Micromechanical analysis on broken samples helped to determine the influence of the solution on the structure of composite pipe and to find out the models and mechanisms which produced decrease of strength.Композиційні матеріали – перспективні замінники металів та сплавів, які традиційно використовують для виготовлення технологічного обладнання хімічної промисловості. Вивчено вплив розчинів метанолу та аміаку на напруження та механічні властивості склополіефірних труб за їх розтягу в поздовжньому та круговому напрямках. Плоскі та кільцеподібні зразки вирізали із труб та випробовували на розтяг за стандартною методикою. Одержані результати порівнювали з даними для труб у вихідному стані. За допомогою мікромеханічного аналізу зруйнованих зразків встановлено характер впливу розчинів на структуру композиційної труби. Розкрито особливості механізму зниження її міцності.Композиционные материалы – перспективные заменители металлов и сплавов, которые традиционно используют для изготовления технологического оборудования химической промышленности. Изучено влияние растворов метанола и аммиака на напряжение и механические свойства стеклополиэфирных труб при их растяжении в продольном и круговом направлениях. Плоские и кольцевидные образцы вырезали из труб и испытывали на растяжение по стандартной методике. Полученные результаты сравнивали с данными для труб в исходном состоянии. С помощью микромеханического анализа разрушенных образцов установлен характер влияния растворов на структуру композиционной трубы. Раскрыты особенности механизма снижения ее прочности

Recent Advances Concerning Certain Class of Geophysical Flows

This paper is devoted to reviewing several recent developments concerning certain class of geophysical models, including the primitive equations (PEs) of atmospheric and oceanic dynamics and a tropical atmosphere model. The PEs for large-scale oceanic and atmospheric dynamics are derived from the Navier-Stokes equations coupled to the heat convection by adopting the Boussinesq and hydrostatic approximations, while the tropical atmosphere model considered here is a nonlinear interaction system between the barotropic mode and the first baroclinic mode of the tropical atmosphere with moisture. We are mainly concerned with the global well-posedness of strong solutions to these systems, with full or partial viscosity, as well as certain singular perturbation small parameter limits related to these systems, including the small aspect ratio limit from the Navier-Stokes equations to the PEs, and a small relaxation-parameter in the tropical atmosphere model. These limits provide a rigorous justification to the hydrostatic balance in the PEs, and to the relaxation limit of the tropical atmosphere model, respectively. Some conditional uniqueness of weak solutions, and the global well-posedness of weak solutions with certain class of discontinuous initial data, to the PEs are also presented.Comment: arXiv admin note: text overlap with arXiv:1507.0523

ASSESMENT OF INTEGRITY OF THE WELDED PIPES

The subject of work includes an analysis of integrity of the welded pipes made of steel API J55 of the high frequency contact welding (HF). Experimental testings of the mechanical properties of the based materials are performed on tubes removed from exploitation after 70 000 hours of work. The impact of damage type of the surface of crack on the integrity of pipe is tested by hydrostatically pressure of tube with an axial surface crack in the base material. The behaviour of fracture was tested using a modified compact testing tubes on tightening (CT), with an initial crack in the base material, welded joint and heat affected zone (HAZ). The critical value of the stress intensity factor CIc is determined on the basis of the critical value of J integral of the JIc. In addition to the experimental research, based on the obtained values for Cr and Sr using the fracture analysis diagram (FAD) is carried out an assessment of the integrity of welded pipes with an axial surface crack on the outer surface

« L'utilisation des prévisions climatiques pour l'agriculture : vers une révolution verte en Afrique de l'Ouest ? »

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Plasma chemical functionalisation of a Cameroonian kaolinite clay for a greater hydrophilicity

A Cameroonian kaolinite powder was treated with gliding arc plasma in order to increase the amount of hydroxyl functional groups present on its external surfaces. The functional changes that occurred were monitored by Fourier transform infrared spectroscopy. The crystalline changes were followed by the X-ray diffraction. The ionisation effect, acid effect, and water solubility of the treated samples were also evaluated. Results showed that there is breaking of the bonds in the Si–O–Si and Si–O–Al groups, followed by the formation of new aluminol (Al–OH) and silanol (Si–OH) groups at the external surface of kaolinite after exposing the clay to the gliding arc plasma. The increase in hydroxyl groups on the surface of kaolinite leads to the increase of its hydrophilicity. Moreover, new charges appear on its surfaces and no significant change in crystallinity has occurred. This study shows that clays in powder form being can effectively be functionalised by gliding arc plasma in spatial post discharge processing mode. Knowing that the treatment in spatial post discharge offers the possibility to process large amounts of clay, this work is of great interest to the industry

La question de la vulnérabilité et de l’adaptation de l’agriculture sahélienne au climat au sein du programme AMMA

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