A three dimensional numerical model for a micro proton exchange membrane fuel cell was developed to simulate the concentration distribution of the fuel gas, and analyze the flow field and current field in the fuel cell. Finite control volume scheme with SIMPLEC algorithm was employed in the numerical method. Various operating conditions on the performance of the fuel cell were studied. It was shown that the concentration of oxygen at the cathode can strongly influence the cell performance. Increase the operating temperature and the pressure of the inlet gas can improve the performance of the fuel cell.

The process of fish migration within rivers and streams is important, especially during the spawning season which often coincides with peak spring discharges in Manitoba. Current environmental regulations for fish passage through culverts require that the average velocity be limited to the prolonged swimming speed of the fish species present. In order to examine the validity of this approach, physical model results were used to calibrate and test a commercially available Computational Fluid Dynamics (CFD) model. Detailed analysis showed that CFD models and the empirical equations used were both able to give a better representation of the flow field than the average velocity. However, the empirical equations were able to provide a more accurate velocity distribution within the fully developed region. A relationship was then developed, to estimate the cumulative percent area less than a threshold velocity within CSP culverts, to be used as a guideline during the design phase.

The process of fish migration within rivers and streams is important, especially during the spawning season which often coincides with peak spring discharges in Manitoba. Current environmental regulations for fish passage through culverts require that the average velocity be limited to the prolonged swimming speed of the fish species present. In order to examine the validity of this approach, physical model results were used to calibrate and test a commercially available Computational Fluid Dynamics (CFD) model. Detailed analysis showed that CFD models and the empirical equations used were both able to give a better representation of the flow field than the average velocity. However, the empirical equations were able to provide a more accurate velocity distribution within the fully developed region. A relationship was then developed, to estimate the cumulative percent area less than a threshold velocity within CSP culverts, to be used as a guideline during the design phase.

The geometry and mineralization features of small left-lateral strike-slip faults and associated fractures in Lake Edison Granodiorite of the central Sierra Nevada, California, were examined in order to model the three-dimensional structure of strike-slip faults. These faults, which are reactivated joints, were also examined to determine fault sizes, starting joint size, and evidence for fluid flow. The associated secondary fractures are usually found in the dilational quadrants of fault-tip regions. The longest fault-segment trace is 32.14 m; the longest joint trace is 22 m. The joint population length (l) is represented by a power-law distribution (l-n) and it is l-1.22. The fault-segment distributions are l-0.23~0.79, and the compiled fault-segment distribution is l-1.18. The data on fracture and fault spacing, along with the joint power-law distribution, will aid in the simulation and analysis of fault evolution. The splay-fracture traced in the faults are linear at depth and the average splay-fracture angle is 39° ± 13°. The dihedral angle of the splay plane and fault plane ranges from 20° to 65°. There is a high concentration of splay fractures near the fault. As distance increases perpendicular form the fault, the splay-fracture spacing increases and splay-fracture frequency decreases. The splay tracelength distributions have a high short tracelength concentration with a rapid decrease of long tracelengths. The maximum tracelength of multiple splay-fracture groups is restricted by their distance orthogonal to the fault trace. The three-dimensional relationship between the splay-fracture plane and fault plane can be inferred from these data. When present, mineralized quartz appears largely as lenses and few as single continuous veins along the faults. No consistent pattern exists between fault displacement and the locations and dimensions of quartz cavities. There is no visible damage zone near the fault termination or around the faults. Microstructures in the fault zone consist of cataclasites and patchy gouges, and zones of dynamically recrystallized fault walls. The three-dimensional geometry, along with quartz cavity distribution and thin section analysis, has led to the conclusion that fluid migrates vertically among the faults and fractures.

BACKGROUND: Calcific aortic valve disease (CAVD) is the most prevalent heart valve disease in the developed world, claiming almost 17,000 deaths annually in the United States. The lack of noninvasive therapeutics to slow or halt the disease warrants the need for further understanding of the pathobiological mechanisms of CAVD. A tri-laminar structure of aortic valve determines the biomechanical properties of its leaflets. Valvular endothelial cells (VECs) and interstitial cells (VICs) are responsible for valve structural integrity. Traditional two-dimensional culture conditions spontaneously activate the pathological differentiation of VICs making in vitro studies challenging. A monolayered three-dimensional (3D) hydrogel platform was recently developed as a novel in vitro culture system to study the phenotypic changes of VICs leading to microcalcification (early stages of calcification). This system, however, did not fully recapitulate the microenvironment of native valve tissues because of the lack of individual layer representations and endothelial coverage. Bioprinting technology, which allows precise and integrated positioning of cells, matrix, and biomolecules, may provide an innovative approach toward building a more biologically relevant 3D culture platform. OBJECTIVE: This study aims to lay the groundwork for building a multilayered 3D-bioprinted culture platform to study CAVD by first validating the use of bioprinting in monolayered cell-laden 3D hydrogel constructs. METHODS: Human VICs were isolated from patients undergoing valve replacement surgeries at Brigham and Women’s Hospital (Boston, MA) according to Institutional Review Board (IRB) protocols. VICs were expanded in culture medium containing growth factors for up to 6 passages and then encapsulated in hydrogels using 3D bioprinting technology. After encapsulation, VIC-laden 3D constructs were cultured in either normal or osteogenic conditions for 21 days. Microcalcification, cell proliferation, and cell apoptosis were evaluated using fluorescent staining and confocal microscopy. Results were compared with results from VIC-laden hydrogels made manually. RESULTS: An increase in microcalcification was observed throughout bioprinted VIC-laden hydrogel constructs cultured in osteogenic conditions for 21 days, whereas normal conditions developed negligible calcification signals. Cell proliferation and apoptosis were not significantly different between normal and osteogenic groups in bioprinted hydrogels. Cell-free hydrogels did not exhibit any microcalcification. Overall, bioprinted hydrogels showed less nonspecific background staining than handmade hydrogels, thus providing a better means for quantitative assessments of 3D culture platforms. CONCLUSION: Based on bioprinting technology, an improved monolayered cell-laden hydrogel platform was successfully established as a first step toward building an in vitro multilayered disease model for studying the pathobiological mechanisms of CAVD. The results in this study were consistent with current literature that proposes calcification as a cell-dependent, apoptotic-independent, and proliferation-independent pathway. / 2019-07-13T00:00:00Z

Oceanic lithosphere constitutes the upper boundary layer of the Earth’s convecting mantle. Its structure and evolution provide a vital window on the dynamics of the mantle and important clues to how the motions of Earth’s surface plates are coupled to convection in the mantle below. The three-dimensional shear-velocity structure of the upper mantle beneath the Atlantic Ocean is investigated to gain insight into processes that drive formation of oceanic lithosphere. Travel times are measured for approximately 10,000 fundamental-mode Rayleigh waves, in the period range 30-130 seconds, traversing the Atlantic basin. Paths with >30% of their length through continental upper mantle are excluded to maximize sensitivity to the oceanic upper mantle. The lateral distribution of Rayleigh wave phase velocity in the Atlantic upper mantle is explored with two approaches. One, phase velocity is allowed to vary only as a function of seafloor age. Two, a general two-dimensional parameterization is utilized in order to capture perturbations to age-dependent structure. Phase velocity shows a strong dependence on seafloor age, and removing age-dependent velocity from the 2-D maps highlights areas of anomalously low velocity, almost all of which are proximal to locations of hotspot volcanism. Depth-dependent variations in vertically-polarized shear velocity (Vsv) are determined with two sets of 3-D models: a layered model that requires constant VSV in each depth layer, and a splined model that allows VSV to vary continuously with depth. At shallow depths (~75 km) the seismic structure shows the expected dependence on seafloor age. At greater depths (~200 km) high-velocity lithosphere is found only beneath the oldest seafloor; velocity variations beneath younger seafloor may result from temperature or compositional variations within the asthenosphere. The age-dependent phase velocities are used to constrain temperature in the mantle and show that, in contrast to previous results for the Pacific, phase velocities for the Atlantic are not consistent with a half-space cooling model but are best explained by a plate-cooling model with thickness of 75 km and mantle temperature of 1400oC. Comparison with data such as basalt chemistry and seafloor elevation helps to separate thermal and compositional effects on shear velocity.

Yes / In this study, a new three-dimensional (3-D) model was developed to provide better understanding of the mechanism for wave-induced seabed response around mono-pile. Based on poro-elastic theory, the fully dynamic (FD) formulations were adopted in the present model to simulate pore water pressure, soil stresses, displacements of both soil and mono-pile. Good agreement between numerical simulation and experimental results was obtained. Based on parametric study, numerical results indicated: (1) wave diffraction and reflection have significant effects on pore water pressure and soil displacements around mono-pile; (2) the most sensitive position for seabed parameter to pore water pressure around mono-pile locates in front of mono-pile while the least sensitive position is at the position of angle 3π/4 with respect to the incident wave direction; and (3) the increase of mono-pile horizontal displacement corresponds to the increase of wave height and the decrease of seabed Young's modulus. / National Science Fund for Distinguished Young Scholars (51425901), the National Natural Science Foundation of China (51209082, 51379071, 41176073), the Specialized Research Fund for the Doctoral Program of Higher Education of China (20120094120006, 20130094110014), the 111 project (B12032), the 333 project of Jiangsu Province (2013Ⅲ-1882)

Medidas atualmente em curso no país, encaminhadas por agentes do setor elétrico, reforçam a expectativa do desenvolvimento de um mercado fotovoltaico sólido em alguns anos. A flexibilidade dos sistemas fotovoltaicos permite a construção de usinas de diferentes capacidades, estas podem estar concentradas, cobrindo vastas áreas de solo, ou distribuídas em pequenas unidades integradas na arquitetura em meio urbano. Entretanto, pesquisas demonstraram que em países com grande capacidade instalada de sistemas fotovoltaicos, o sombreamento parcial de módulos fotovoltaicos é responsável por perdas médias de 10%. Visando agregar conhecimento ao setor energético e contribuir com o desenvolvimento do mercado fotovoltaico nacional, esse texto tem o objetivo de apresentar os resultados de uma pesquisa, em que foi estabelecido um modelo utilizado para construir um plug-in, que transforma o Google SketchUp em uma ferramenta gratuita para estimar o fator de sombreamento e a irradiação em superfícies selecionadas em um modelo tridimensional de uma edificação. Assim, foi conduzida uma pesquisa bibliográfica responsável por identificar e selecionar modelos utilizados nas diversas etapas envolvidas com a estimativa do fator de sombreamento e irradiação. Realizadas algumas alterações, esses modelos convergiram para um modelo único que foi aplicado ao desenvolvimento de um plug-in, denominado Solar3DBR. O desempenho do Solar3DBR foi avaliado através de comparações com os softwares PVsyst e Ecotect, e também por meio de medições reais realizadas em um experimento onde foi monitorada a irradiância em uma célula fotovoltaica parcialmente sombreada e a irradiação horária em plano inclinado. Os resultados das medições permitiram determinar o fator de sombreamento da célula e estes foram comparados aos resultados da simulação de um modelo tridimensional do sistema através do Solar3DBR. Essas confrontações demonstraram que as simulações realizadas com o Solar3DBR apresentam grande proximidade com os resultados apresentados por PVsyst, Ecotect e medições reais. / Measures that are currently underway in the country, forwarded by agents of the electricity sector, reinforce the expectation of developing a solid photovoltaic market in a few years. The photovoltaic systems flexibility, allows plant\'s construction of different capacities, these may be concentrated, covering vast areas of land, as divided into small units, integrated into urban architecture. However, researches have shown that in countries with a large capacity of photovoltaic systems installed, the partial shading of photovoltaic modules is responsible for average losses of 10%. Aiming to add knowledge to the energy sector and contribute to the development of the domestic photovoltaic market, this text aims to present the results of a research, in which was established a model used to build a plug-in that turns Google SketchUp into a free tool, with the ability to estimate the shading factor and irradiation in selected surfaces in a three-dimensional model of a building. Thus, was realized a literature research, responsible for identifying and selecting models used in the various steps, involved in estimating the shading factor and irradiation. After some changes have been implemented, these models converged to a single model that was applied to the development of a plug-in called Solar3DBR. The performance of the Solar3DBR was evaluated through comparisons with the softwares PVsyst and Ecotect, and in actual measurements performed in an experiment. In this experiment irradiance in a partially shaded PV cell and hourly irradiation on inclined plane were monitored. Measurement results allowed to determine the shading factor of the cell, and were compared to simulation results of a three-dimensional model of the system through Solar3DBR. The result of these confrontations demonstrated that the results obtained from the Solar3DBR are similar to the ones presented by PVsyst, Ecotect and actual measurements.

Medidas atualmente em curso no país, encaminhadas por agentes do setor elétrico, reforçam a expectativa do desenvolvimento de um mercado fotovoltaico sólido em alguns anos. A flexibilidade dos sistemas fotovoltaicos permite a construção de usinas de diferentes capacidades, estas podem estar concentradas, cobrindo vastas áreas de solo, ou distribuídas em pequenas unidades integradas na arquitetura em meio urbano. Entretanto, pesquisas demonstraram que em países com grande capacidade instalada de sistemas fotovoltaicos, o sombreamento parcial de módulos fotovoltaicos é responsável por perdas médias de 10%. Visando agregar conhecimento ao setor energético e contribuir com o desenvolvimento do mercado fotovoltaico nacional, esse texto tem o objetivo de apresentar os resultados de uma pesquisa, em que foi estabelecido um modelo utilizado para construir um plug-in, que transforma o Google SketchUp em uma ferramenta gratuita para estimar o fator de sombreamento e a irradiação em superfícies selecionadas em um modelo tridimensional de uma edificação. Assim, foi conduzida uma pesquisa bibliográfica responsável por identificar e selecionar modelos utilizados nas diversas etapas envolvidas com a estimativa do fator de sombreamento e irradiação. Realizadas algumas alterações, esses modelos convergiram para um modelo único que foi aplicado ao desenvolvimento de um plug-in, denominado Solar3DBR. O desempenho do Solar3DBR foi avaliado através de comparações com os softwares PVsyst e Ecotect, e também por meio de medições reais realizadas em um experimento onde foi monitorada a irradiância em uma célula fotovoltaica parcialmente sombreada e a irradiação horária em plano inclinado. Os resultados das medições permitiram determinar o fator de sombreamento da célula e estes foram comparados aos resultados da simulação de um modelo tridimensional do sistema através do Solar3DBR. Essas confrontações demonstraram que as simulações realizadas com o Solar3DBR apresentam grande proximidade com os resultados apresentados por PVsyst, Ecotect e medições reais. / Measures that are currently underway in the country, forwarded by agents of the electricity sector, reinforce the expectation of developing a solid photovoltaic market in a few years. The photovoltaic systems flexibility, allows plant\'s construction of different capacities, these may be concentrated, covering vast areas of land, as divided into small units, integrated into urban architecture. However, researches have shown that in countries with a large capacity of photovoltaic systems installed, the partial shading of photovoltaic modules is responsible for average losses of 10%. Aiming to add knowledge to the energy sector and contribute to the development of the domestic photovoltaic market, this text aims to present the results of a research, in which was established a model used to build a plug-in that turns Google SketchUp into a free tool, with the ability to estimate the shading factor and irradiation in selected surfaces in a three-dimensional model of a building. Thus, was realized a literature research, responsible for identifying and selecting models used in the various steps, involved in estimating the shading factor and irradiation. After some changes have been implemented, these models converged to a single model that was applied to the development of a plug-in called Solar3DBR. The performance of the Solar3DBR was evaluated through comparisons with the softwares PVsyst and Ecotect, and in actual measurements performed in an experiment. In this experiment irradiance in a partially shaded PV cell and hourly irradiation on inclined plane were monitored. Measurement results allowed to determine the shading factor of the cell, and were compared to simulation results of a three-dimensional model of the system through Solar3DBR. The result of these confrontations demonstrated that the results obtained from the Solar3DBR are similar to the ones presented by PVsyst, Ecotect and actual measurements.

Matematinis dantų lanko modeliavimas leidžia įvertinti funkcinę tam tikro paciento dantų lanko būklę ir analizuoti racionalius gydymo variantus. Dabar mechaninė žmogaus kramtomosios sistemos analizė sujungia daugiau anatominių detalių ir todėl žmogui gali atrodyti, jog pagrindinės mechaninės problemos yra išsprendžiamos. Deja, tai nėra tiesa. Viena iš pagrindinių problemų susieta su raumenų stiprinimu - ar turime mes aktyvinti savo kramtymo raumenis ir kodėl. Pradžioje ištyrėme probleminę sritį ir iki šiol gautus pasiekimus žmogaus kramtymo sistemos trimačiame modeliavime. Vėliau parinkome tinkamą programinę įrangą bei susipažinome su jos galimybėmis. Tada įvairių bandymų metu nustatėme kaip įvairios naudojamų programų funkcijos ir jų parametrai įtakoja duomenų apdorojimą ir remdamiesi šiais duomenimis sudarėme žmogaus kramtymo sistemos trimačio modeliavimo algoritmą. Pasinaudodami juo sukūrėme trimatį paciento kramtymo sistemos modelį. Šio darbo tikslas buvo pasirinkti įrankius bei sukurti naujus, kurie gali pagelbėti sudarant trimatį modelį iš tomografijos būdu gaut�� vaizdų. Turėjome atsižvelgti į taisykles ir apribojimus. Pagrindinis šio darbo rezultatas yra makro komanda sukurta „Image-Pro Plus“ programai, kuri yra naudojama koordinačių gavimui iš tomografijos būdu gautų vaizdų. Buvo daryti eksperimentai skirti apibrėžti faktoriams, įtakojantiems sukuriamo modelio kokybę. / Relationships between muscle tensions, jaw motions, bite and joint forces, and craniofacial morphology are not fully understood, and critical information is often difficult or impossible to obtain in experiments on living humans. The inaccessibility of the mandible and its related structures is a major obstacle to measure their internal forces and stresses, and understanding their effects. Computer modeling offers an alternative method for doing this. Despite its limitations, modeling appears to provide a useful conceptual framework for developing hypotheses regarding the role of stresses during human masticatory system function. Three-dimensional model of main elements of masticatory system was created from computed tomography images. Later this model will be improved with physical characteristics. The objective of this work is to select the set of tools and create the new ones which could be used to acquire the three dimensional model from tomography images. The rules and restrictions of using medical hardware should be taken into account. The main outcome of this work is a macro-command created for the “Image Pro Plus”, which is used to capture object coordinates from the tomography pictures. Experiments were made to define the factors which are influencing the quality of the created model.