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Shielding effects and buckling of steel tanks in tandem arrays under wind pressures
Portela, Genock,Godoy, Luis A. Techno-Press 2005 Wind and Structures, An International Journal (WAS Vol.8 No.5
This paper deals with the buckling behavior of thin-walled aboveground tanks under wind load. In order to do that, the wind pressures are obtained by means of wind-tunnel experiments, while the structural non linear response is computed by means of a finite element discretization of the tank. Wind-tunnel models were constructed and tested to evaluate group effects in tandem configurations, i.e. one or two tanks shielding an instrumented tank. Pressures on the roof and on the cylindrical part were measured by pressure taps. The geometry of the target tank is similar in relative dimensions to typical tanks found in oil storage facilities, and several group configurations were tested with blocking tanks of different sizes and different separation between the target tank and those blocking it. The experimental results show changes in the pressure distributions around the circumference of the tank for half diameter spacing, with respect to an isolated tank with similar dimensions. Moreover, when the front tank of the tandem array has a height smaller than the target tank, increments in the windward pressures were measured. From the computational analysis, it seems that the additional stiffness provided by the roof prevents reductions in the buckling load for cases even when increments in pressures develop in the top region of the cylinder.
Wind pressure and buckling of grouped steel tanks
Portela, Genock,Godoy, Luis A. Techno-Press 2007 Wind and Structures, An International Journal (WAS Vol.10 No.1
Wind tunnel experiments on small scale groups of tanks are reported in the paper, with the aim of evaluating the pressure patterns due to group effects. A real tank configuration is studied in detail because one tank buckled during a hurricane category 3. Three configurations are studied in a wind tunnel, two with several tanks and different wind directions, and a third one with just one blocking tank. The pressures were measured in the cylindrical part and in the roof of the tank, in order to obtain pressure coefficients. Next, computational buckling analyses were carried out for the three configurations to evaluate the buckling pressure of the target structure. Finally, imperfection-sensitivity was investigated for one of the configurations, and moderate sensitivity was found, with reductions in the maximum load of the order of 25%. The results help to explain the buckling of the tank for the levels of wind experienced during the hurricane.
Wind pressure and buckling of grouped steel tanks
Genock Portela,Luis A. Godoy 한국풍공학회 2007 Wind and Structures, An International Journal (WAS Vol.10 No.1
Wind tunnel experiments on small scale groups of tanks are reported in the paper, with the aim of evaluating the pressure patterns due to group effects. A real tank configuration is studied in detail because one tank buckled during a hurricane category 3. Three configurations are studied in a wind tunnel, two with several tanks and different wind directions, and a third one with just one blocking tank. The pressures were measured in the cylindrical part and in the roof of the tank, in order to obtain pressure coefficients. Next, computational buckling analyses were carried out for the three configurations to evaluate the buckling pressure of the target structure. Finally, imperfection-sensitivity was investigated for one of the configurations, and moderate sensitivity was found, with reductions in the maximum load of the order of 25%. The results help to explain the buckling of the tank for the levels of wind experienced during the hurricane.
Patino-Portela, Melissa C.,Arciniegas-Grijalba, Paola A.,Mosquera-Sanchez, Lyda P.,Sierra, Beatriz E. Guerra,Munoz-Florez, Jaime E.,Erazo-Castillo, Luis A.,Rodriguez-Paez, Jorge E. Techno-Press 2021 Advances in nano research Vol.10 No.2
To compare the antifungal effect of two nanomaterials (NMs), nanoparticles of zinc oxide were synthesized by a chemical route and zinc oxide-based nanobiohybrids were obtained using green synthesis in an extract of garlic (Allium sativum). The techniques of X-Ray Diffraction (XRD), Infrared (IR) and Ultraviolet Visible (UV-Vis) absorption spectroscopies and Scanning (SEM) and Transmission Electron Microscopies (TEM) were used to determine the characteristics of the nanomaterials synthesized. The results showed that the samples obtained were of nanometric size (< 100 nm). To compare their antifungal capacity, their effect on Cercospora sp. was evaluated. Test results showed that both nanomaterials had an antifungal capacity. The nanobiohybrids (green route) gave an inhibition of fungal growth of ~72.4% while with the ZnO-NPs (chemical route), inhibition was ~87.1%. Microstructural studies using High Resolution Optical Microscopy (HROM) and ultra-structural analysis using TEM carried out on the treated strains demonstrated the effect of the nanofungicides on the vegetative and reproductive structures, as well as on their cell wall. To account for the antifungal effect presented by ZnO-NPs and ZnO nanobiohybrids on the fungi tested, effects reported in the literature related to the action of nanomaterials on biological entities were considered. Specifically, we discuss the electrical interaction of the ZnO-NPs with the cell membrane and the biomolecules (proteins) present in the fungi, taking into account the n-type nature of the ZnO semiconductor and the electrical behavior of the fungal cell membrane and that of the proteins that make up the protein crown.
A simple and effective method for addition silicone impression disinfection
Azevedo, Maria Joao,Correia, Ines,Portela, Ana,Sampaio-Maia, Benedita The Korean Academy of Prosthodonitics 2019 The Journal of Advanced Prosthodontics Vol.11 No.3
PURPOSE. Although dental impression disinfection is determinant to reduce the cross-infection risk, some studies have shown that, in real practice, the disinfection procedures vary considerably. Thus, the aim of this study was to evaluate the antimicrobial effectiveness and the impact on the dimensional stability of addition silicone' impressions of water wash and the most clinically used disinfection solutions: 3% hydrogen peroxide, commercial disinfectant MD520 (Durr) and 1% and 5.25% sodium hypochlorite. MATERIALS AND METHODS. For this investigation, dental impressions were taken on 16 volunteer dental students. The antimicrobial effectiveness of each procedure was evaluated by pour plate method. The dimensional stability was evaluated using a standardized stainless-steel model, according to ANSI/ADA nº19 specification. RESULTS. The study results showed that water wash does not alter the dimensional stability of addition silicone impressions but doesn't reduce the microbial load of the material (P>.05). On the other hand, addition silicone disinfection by immersion with 3% hydrogen peroxide, MD520 (Durr), or sodium hypochlorite at 1% and 5.25% does not alter the dimensional stability significantly but reduces > 99.9% of the microbial load of the impressions (P<.001). CONCLUSION. Addition silicone impressions should always be disinfected after water wash in order to reduce effectively the cross-infection risk. All disinfectants tested showed high antimicrobial efficiency without significant changes in three-dimensional shape of impressions. Hydrogen peroxide and sodium hypochlorite are of particular importance because are easily accessible in dental setting. The less explored hydrogen peroxide could be a valuable alternative for silicone impressions disinfection.
부소영(Soyoung Bu),Stefan Boehm,Miguel Portela,조현제(Hyunjei Jo) 한국정보과학회 2007 한국정보과학회 학술발표논문집 Vol.34 No.1C
본 논문에서는 제품 공정에서 스타일링과 디자인 과정에서 제작하게 되는 다양한 재질의 Digital-Mockup을 품평하기 위한 시스템을 제안한다. 타일드 디스플레이, 워크벤치, 혼합현실 디스플레이, 데스크탑 디스플레이와 같은 여러 가상 환경에서의 다자간 연결을 통해 원거리 참여자들이 공유된 시각 작업공간상에서 원활한 협업을 수행할 수 있도록 지원한다. 또한 모바일을 이용하여 씬-그래프(scenegraph)에 나타나는 3차원 제품 모델의 재질 정보를 실시간으로 변경이 가능하다.
Use of supercritical methanol/carbon dioxide mixtures for biodiesel production
María Belén García-Jarana,Jezabel Sánchez-Oneto,Juan Ramón Portela,Lourdes Casas,Casimiro Mantell,Enrique Martínez de la Ossa 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.8
The use of supercritical conditions for the production of biodiesel from both vegetables oils and waste-oils may be of great industrial interest because it can be carried out without those catalysts necessary in the conventional transesterification process, therefore avoiding a complex separation between the product and the catalyst. However, the use of supercritical alcohol requires higher operating temperatures and pressures. In this work, CO2 was added to the reaction mixture in order to reduce the operating conditions (temperature, pressure and molar ratio of alcohol to vegetable oil). The novelty of using CO2 may have two advantages: a possible combination of supercritical CO2 extraction of the oil and its subsequent transesterification reaction without CO2 depressurization, and a reduction of the supercritical temperature and pressure of the mixture. The effects of temperature (280-350 oC), pressure (140-280 bar), methanol- to-oil molar ratio (20-30), CO2-to-methanol molar ratio (0.05-0.2) and residence time (0-45minutes) on the yield of methyl esters (biodiesel) were studied in a batch reactor, obtaining in all cases a relatively low increase in the yield when CO2 was present in the medium. The yields of biodiesel were tested with three vegetable oils used as model compounds (palm, sunflower and borage), obtaining similar results.