WorldWideScience

Sample records for providing open porosity

  1. Reducing the open porosity of pyroboroncarbon articles

    Science.gov (United States)

    Martyushov, G. G.; Zakharevich, A. M.; Pichkhidze, S. Ya.; Koshuro, V. A.

    2016-02-01

    It is established that a decrease in the open porosity of pyroboroncarbon, a pyrolytic glassy composite material of interest for manufacturing prosthetic heart valves (PHVs), can be achieved via impregnation of articles with an alcohol solution of 3-aminopropyltriethoxysilane and subsequent thermal treatment. The maximum roughness height and linear size of open pores on the surface of PHV parts made of pyroboroncarbon can additionally be reduced by final mechanical processing of a silicon oxide film formed on the surface.

  2. Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs.

    Directory of Open Access Journals (Sweden)

    Kohei Tanaka

    Full Text Available Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1 covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes, and 2 open nests, in which eggs are exposed in the nest and brooded (as in most birds. Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1 covered nests are likely the primitive condition for dinosaurs (and probably archosaurs, and 2 open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment

  3. Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs.

    Science.gov (United States)

    Tanaka, Kohei; Zelenitsky, Darla K; Therrien, François

    2015-01-01

    Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1) covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes), and 2) open nests, in which eggs are exposed in the nest and brooded (as in most birds). Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity) of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1) covered nests are likely the primitive condition for dinosaurs (and probably archosaurs), and 2) open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids) were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment. Open nests

  4. METHODS AND DEVICES FOR CONTROL OF OPEN MICROSCOPIC POROSITY OF PORCELAIN INSULATORS

    OpenAIRE

    Galagan, Roman

    2014-01-01

    Examined the methods and devices of control of porcelain insulators for presence of defects such as open microscopic porosity. It is shown that open microscopic porosity is the most dangerous defect production origin and is responsible for over 80% of failures of porcelain support insulators. Considered methods of control are divided into two groups: destructive and non-destructive. For each method are highlighted their advantages and disadvantages. The analysis showed that most of the existi...

  5. Cooling capacity of high porosity open-cell metal foams as passive cryogenic radiators

    Science.gov (United States)

    Dixit, Tisha; Ghosh, Indranil

    2017-06-01

    This work presents an innovative avenue for employment of high porosity open-cell metal foams as extended heat transfer surfaces in passive cryogenic radiators. Metal foams are known for being light in weight and possess high surface area density. In contrast to a solid surface, porosity of metal foams makes it feasible for penetration of radiation thereby resulting in higher radiatively interactive surface area. Two 20 PPI metal foams made of copper and aluminum with 94.9% and 90.3% porosity respectively have been chosen for this study. A laboratory-scale test rig measures the radiative cooling capacity of metal foams in vacuum (10-6 mbar) subjected to liquid nitrogen environment. Heat load to the foam has been provided by means of convective fluid loop. Simultaneously, a theoretical model based on radiation-conduction fin analysis has been developed to predict the foam cooling capacity at a specified temperature. The required radiation heat transfer coefficient has been obtained from a previous experiment wherein the foam samples are freely suspended in similar conditions but with no heat load. Lastly, performance of the foams under study has been expressed in terms of a commonly used performance parameter (surface area/cooling capacity) for passive cryogenic radiators.

  6. Open die forging of large shafts with porosity defects – physical and numerical modelling

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Bay, Niels

    2013-01-01

    The aim and scope of this paper is centered to analyze the influence of the geometry of V-shaped dies on the closure of internal centerline porosity defects in ingots during multistep open-die forging. The investigation is performed with small scale physical models made from lead using V-shaped d......The aim and scope of this paper is centered to analyze the influence of the geometry of V-shaped dies on the closure of internal centerline porosity defects in ingots during multistep open-die forging. The investigation is performed with small scale physical models made from lead using V...

  7. Development of сertified reference materials set for opened porosity of solid substances and materials (imitators

    Directory of Open Access Journals (Sweden)

    E. P. Sobina

    2016-01-01

    Full Text Available The article deals with data of research for development of certified reference materials set for opened porosity of solid substances and materials (imitators (OPTB SO UNIIM Set Certified Reference Materials GSO 10583-2015. The certified values of opened porosity of metal cylinders were established by the method of hydrostatic weighing before and after boring of holes in. The certified reference materials are intended for calibration and verification of measuring instruments of opened porosity, based on the Boyle - Mariotte's law.

  8. An Open Service Provider Concept for Enterprise Complex Automation

    Science.gov (United States)

    Ivaschenko, A. V.; Sitnikov, P. V.; Tanonykhina, M. O.

    2017-01-01

    The paper introduces a solution for IT services representation and management in the integrated information space of distributed enterprises. It is proposed to develop an Open Service Provider as a software platform for interaction between IT services providers and their users. Implementation of the proposed concept and approach is illustrated by an after-sales customer support system for a large manufacturing corporation delivered by SEC “Open Code”.

  9. Daylighting provided by horizontal openings using the illumination vector

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, J.; Sendra, J.J. [Instituto Universitario de Ciencias de la Construccion, Universidad de Sevilla (Spain)

    2006-12-15

    Stemming from the expressions of the illumination vector provided by vertical openings at any point of the interior space, this article proposes and solves the equivalent expressions for openings in horizontal planes, thus completing the expressions of Navarro [Sobre iluminacion natural en arquitectura. Ed. Secretariado de Publicaciones de la Universidad de Sevilla; 1983] and offering algorithms which give the value of the illumination vector for CIE skies [Natural daylight official recommendations. Paris: CIE COMMITE 3.2.; 1955] at any point of the interior space and for any size of window whether vertical or horizontal. This constitutes a highly potential tool of computerized calculation of the direct component of natural illumination which is eminently more flexible and precise than those systems which are based on finite elements. (author)

  10. Sustainable Business Models for Public Sector Open Data Providers

    NARCIS (Netherlands)

    Welle Donker, F.M.; van Loenen, B.

    2016-01-01

    Since 2009, Open Government Data initiatives have been launched worldwide and the concept of open data is gaining momentum. Open data are often associated with realizing ambitions, such as a more transparent and efficient government, solving societal problems and increased economic value. However,

  11. Microparticles with hierarchical porosity

    Science.gov (United States)

    Petsev, Dimiter N; Atanassov, Plamen; Pylypenko, Svitlana; Carroll, Nick; Olson, Tim

    2012-12-18

    The present disclosure provides oxide microparticles with engineered hierarchical porosity and methods of manufacturing the same. Also described are structures that are formed by templating, impregnating, and/or precipitating the oxide microparticles and method for forming the same. Suitable applications include catalysts, electrocatalysts, electrocatalysts support materials, capacitors, drug delivery systems, sensors and chromatography.

  12. Liquids with permanent porosity

    Science.gov (United States)

    Giri, Nicola; Del Pópolo, Mario G.; Melaugh, Gavin; Greenaway, Rebecca L.; Rätzke, Klaus; Koschine, Tönjes; Pison, Laure; Gomes, Margarida F. Costa; Cooper, Andrew I.; James, Stuart L.

    2015-11-01

    Porous solids such as zeolites and metal-organic frameworks are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption-desorption cycles, but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages, but permanent porosity is not associated with conventional liquids. Here we report free-flowing liquids whose bulk properties are determined by their permanent porosity. To achieve this, we designed cage molecules that provide a well-defined pore space and that are highly soluble in solvents whose molecules are too large to enter the pores. The concentration of unoccupied cages can thus be around 500 times greater than in other molecular solutions that contain cavities, resulting in a marked change in bulk properties, such as an eightfold increase in the solubility of methane gas. Our results provide the basis for development of a new class of functional porous materials for chemical processes, and we present a one-step, multigram scale-up route for highly soluble ‘scrambled’ porous cages prepared from a mixture of commercially available reagents. The unifying design principle for these materials is the avoidance of functional groups that can penetrate into the molecular cage cavities.

  13. Porosity Assessment for Different Diameters of Coir Lignocellulosic Fibers

    Science.gov (United States)

    da Luz, Fernanda Santos; Paciornik, Sidnei; Monteiro, Sergio Neves; da Silva, Luiz Carlos; Tommasini, Flávio James; Candido, Verônica Scarpini

    2017-10-01

    The application of natural lignocellulosic fibers (LCFs) in engineering composites has increased interest in their properties and structural characteristics. In particular, the inherent porosity of an LCF markedly affects its density and the adhesion to polymer matrices. For the first time, both open and closed porosities of a natural LCF, for different diameter ranges, were assessed. Fibers extracted from the mesocarp of the coconut fruit were investigated by nondestructive methods of density measurements and x-ray microtomography (microCT). It was found that, for all diameter ranges, the closed porosity is significantly higher than the open porosity. The total porosity increases with diameter to around 60% for coir fibers with more than 503 μm in diameter. The amount and characteristics of these open and closed porosities were revealed by t test and Weibull statistics as well as by microCT.

  14. Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes

    Science.gov (United States)

    Martin, Thomas E.; Boyce, Andy J.; Fierro-Calderon, Karolina; Mitchell, Adam E.; Armstad, Connor E.; Mouton, James C.; Bin Soudi, Evertius E.

    2017-01-01

    Nest structure is thought to provide benefits that have fitness consequences for several taxa. Traditionally, reduced nest predation has been considered the primary benefit underlying evolution of nest structure, whereas thermal benefits have been considered a secondary or even non-existent factor. Yet, the relative roles of these factors on nest structures remain largely unexplored.Enclosed nests have a constructed or natural roof connected to sides that allow a restricted opening or tube entrance that provides cover in all directions except the entrance, whereas open nests are cups or platforms that are open above. We show that construction of enclosed nests is more common among songbirds (Passeriformes) in tropical and southern hemisphere regions than in north temperate regions. This geographic pattern may reflect selection from predation risk, under long-standing assumptions that nest predation rates are higher in southern regions and that enclosed nests reduce predation risk compared with open cup nests. We therefore compared nest predation rates between enclosed vs. open nests in 114 songbird species that do not nest in tree holes among five communities of coexisting birds, and for 205 non-hole-nesting species from the literature, across northern temperate, tropical, and southern hemisphere regions.Among coexisting species, enclosed nests had lower nest predation rates than open nests in two south temperate sites, but not in either of two tropical sites or a north temperate site. Nest predation did not differ between nest types at any latitude based on literature data. Among 319 species from both our field studies and the literature, enclosed nests did not show consistent benefits of reduced predation and, in fact, predation was not consistently higher in the tropics, contrary to long-standing perspectives.Thermal benefits of enclosed nests were indicated based on three indirect results. First, species that built enclosed nests were smaller than species using

  15. Scaffolding open inquiry: How a teacher provides students with structure and space

    Directory of Open Access Journals (Sweden)

    Birgitte Bjønness

    2015-11-01

    Full Text Available The present case study examines a teacher’s scaffolding strategies supporting his students during a twelve-week open inquiry project at an upper secondary school. We use interaction analysis to identify how he provides structure and space in the different phases of open inquiry as well as how it constitutes the students’ inquiry process. The study reveals that the teacher scaffolded this open inquiry in two opposing ways; he created space for the students to make their own experiences and ideas, which eventually set up the need for more directed scaffolding to discuss the challenges students experienced, and directing students’ ideas in certain directions in phases with structure. We suggest that the interplay between structure and space creates what can be seen as a driving force providing both exploration and direction for open inquiry. Moreover, we propose that the dual concept of ‘structure and space’ can work as a thinking tool to promote teachers’ competence on how to scaffold more authentic versions of scientific inquiry in schools.

  16. Porosity variation in chalk

    DEFF Research Database (Denmark)

    Lind, Ida; Grøn, Peter

    1996-01-01

    Vertical porosity variations in chalk are generally assumed to result from either a vaguely defined combination of primary sedimentary and diagenetic processes or solely to diagenetic processes. In this study, image analysis of backscatter electron images of polished samples and geochemical...

  17. Providing open hydrological data for decision making and research - hypeweb.smhi.se

    Science.gov (United States)

    Strömbäck, Lena; Andersson, Jafet; Donnelly, Chantal; Gustafsson, David; Isberg, Kristina; Pechlivanidis, Ilias; Strömqvist, Johan; Arheimer, Berit

    2015-04-01

    Following the EU open data strategy the Swedish Meteorological and Hydrological Institute (SMHI) is providing large parts of their databases openly available. These data are ranging from historical observations to climate predictions in various areas such as weather, oceanography and hydrology. In this presentation we will focus on the work on making hydrological data openly available. Hydrological modelling demands large amounts of spatial data, such as soil properties, land use, topography, lakes and reservoirs, ice and snow coverage, water management (e.g. irrigation patterns and regulations), meteorological data and observed water discharge in rivers. By using such data, the hydrological model will in turn provide new data that can be used for new purposes (i.e. re-purposing). In the presentation we will focus on how readily available open data from public portals have been re-purposed by using the Hydrological Predictions for the Environment (HYPE) model in a number of large-scale model applications covering numerous subbasins and rivers. HYPE is a dynamic, semi-distributed, process-based, and integrated catchment model. So far, the following regional domains have been modelled with different resolutions (number of subbasins within brackets): Sweden (37 000), Europe (35 000), Arctic basin (30 000), La Plata River (6 000), Niger River (800), Middle-East North-Africa (31 000), and the Indian subcontinent (6 000). The model output is launched as new Open Data at the web site www.hypeweb.smhi.se. The web site provides several interactive applications for exploring results from the models. The user can explore an overview of various water variables for historical and future conditions. Moreover the user can explore and download historical time series of discharge for each basin and explore the performance of the model towards observed river flow. The available results can be used for many different purposes including; (i) Climate change impact assessments on water

  18. Investment in Open Innovation Service Providers: NASA's Innovative Strategy for Solving Space Exploration Challenges

    Science.gov (United States)

    Fogarty, Jennifer A.; Rando, Cynthia; Baumann, David; Richard, Elizabeth; Davis, Jeffrey

    2010-01-01

    In an effort to expand routes for open communication and create additional opportunities for public involvement with NASA, Open Innovation Service Provider (OISP) methodologies have been incorporated as a tool in NASA's problem solving strategy. NASA engaged the services of two OISP providers, InnoCentive and Yet2.com, to test this novel approach and its feasibility in solving NASA s space flight challenges. The OISPs were chosen based on multiple factors including: network size and knowledge area span, established process, methodology, experience base, and cost. InnoCentive and Yet2.com each met the desired criteria; however each company s approach to Open Innovation is distinctly different. InnoCentive focuses on posting individual challenges to an established web-based network of approximately 200,000 solvers; viable solutions are sought and granted a financial award if found. Based on a specific technological need, Yet2.com acts as a talent scout providing a broad external network of experts as potential collaborators to NASA. A relationship can be established with these contacts to develop technologies and/or maintained as an established network of future collaborators. The results from the first phase of the pilot study have shown great promise for long term efficacy of utilizing the OISP methodologies. Solution proposals have been received for the challenges posted on InnoCentive and are currently under review for final disposition. In addition, Yet2.com has identified new external partners for NASA and we are in the process of understanding and acting upon these new opportunities. Compared to NASA's traditional routes for external problem solving, the OISP methodologies offered NASA a substantial savings in terms of time and resources invested. In addition, these strategies will help NASA extend beyond its current borders to build an ever expanding network of experts and global solvers.

  19. The Hellenic Open University: providing opportunities for personal and professional development

    Directory of Open Access Journals (Sweden)

    Barbara Koziori

    2011-02-01

    Full Text Available This paper examines and discusses the position of the Hellenic Open University (HOU as the main provider of higher adult education via Open and Distance Education (ODE in Greece, and the role it plays both locally and internationally. It also attempts a clear, albeit brief, presentation of the structure and organisation of the MEd course for English as a Foreign Language (EFL teachers provided by the HOU, which along with a postgraduate course in ODE, were the first courses offered by the HOU in 1998 when it admitted its first students. Such presentation is followed by a discussion of the true training and developmental nature of the course based on the elements constituting O’Brien’s EROTI model. Finally, suggestions are made with regard to the improvement of the postgraduate course under examination so as the effects thereof are granted permanence status and, therefore, being really beneficial for its participants, who then will not only be able to constantly pursue their personal and professional development through a reflective approach to teacher education, but also integrate more learner-centred techniques in their daily practice for the benefit of their students.

  20. On providing the fault-tolerant operation of information systems based on open content management systems

    Science.gov (United States)

    Kratov, Sergey

    2018-01-01

    Modern information systems designed to service a wide range of users, regardless of their subject area, are increasingly based on Web technologies and are available to users via Internet. The article discusses the issues of providing the fault-tolerant operation of such information systems, based on free and open source content management systems. The toolkit available to administrators of similar systems is shown; the scenarios for using these tools are described. Options for organizing backups and restoring the operability of systems after failures are suggested. Application of the proposed methods and approaches allows providing continuous monitoring of the state of systems, timely response to the emergence of possible problems and their prompt solution.

  1. 47 CFR 76.1503 - Carriage of video programming providers on open video systems.

    Science.gov (United States)

    2010-10-01

    ... shall be “Open Video System Notice of Intent” and “Attention: Media Bureau.” This wording shall be... Notice of Intent with the Office of the Secretary and the Bureau Chief, Media Bureau. The Notice of... capacity through a fair, open and non-discriminatory process; the process must be insulated from any bias...

  2. Testing Open-Air Storage of Stumps to Provide Clean Biomass for Energy Production

    Directory of Open Access Journals (Sweden)

    Luigi Pari

    2017-10-01

    Full Text Available When orchards reach the end of the productive cycle, the stumps removal becomes a mandatory operation to allow new soil preparation and to establish new cultivations. The exploitation of the removed stump biomass seems a valuable option, especially in the growing energy market of the biofuels; however, the scarce quality of the material obtained after the extraction compromises its marketability, making this product a costly waste to be disposed. In this regard, the identification of affordable strategies for the extraction and the cleaning of the material will be crucial in order to provide to plantation owners the chance to sell the biomass and offset the extraction costs. Mechanical extraction and cleaning technologies have been already tested on forest stumps, but these systems work on the singular piece and would be inefficient in the conditions of an intensive orchard, where stumps are small and numerous. The objective of this study was to test the possibility to exploit a natural stumps cleaning system through open-air storage. The tested stumps were obtained from two different vineyards, extracted with an innovative stump puller specifically designed for continuous stump removal in intensively-planted orchards. The effects of weathering were evaluated to determine the fuel quality immediately after the extraction and after a storage period of six months with respect to moisture content, ash content, and heating value. Results indicated interesting storage performance, showing also different dynamics depending on the stumps utilized.

  3. Providing Open-Access Know How for Directors of Quantitative and Mathematics Support Centers

    Directory of Open Access Journals (Sweden)

    Michael Schuckers

    2017-01-01

    Full Text Available The purpose of this editorial is to introduce the quantitative literacy community to the newly published A Handbook for Directors of Quantitative and Mathematics Centers. QMaSCs (pronounced “Q-masks” can be broadly defined as centers that have supporting students in quantitative fields of study as part of their mission. Some focus only on calculus or mathematics; others concentrate on numeracy or quantitative literacy, and some do all of that. A QMaSC may be embedded in a mathematics department, or part of a learning commons, or a stand-alone center. There are hundreds of these centers in the U.S. The new handbook, which is the outgrowth of a 2013 NSF-sponsored, national workshop attended by 23 QMaSC directors from all quarters of the U.S., is available open access on the USF Scholar Commons and in hard copy from Amazon.com. This editorial by the handbook’s editors provides background and overview of the 20 detailed chapters on center leadership and management; community interactions; staffing, hiring and training; center assessment; and starting a center; and then a collection of ten case studies from research universities, four-year state colleges, liberal arts colleges, and a community college. The editorial ends by pointing out the need and potential benefits of a professional organization for QMaSC directors.

  4. Permeability-porosity relationships in sedimentary rocks

    Science.gov (United States)

    Nelson, Philip H.

    1994-01-01

    In many consolidated sandstone and carbonate formations, plots of core data show that the logarithm of permeability (k) is often linearly proportional to porosity (??). The slope, intercept, and degree of scatter of these log(k)-?? trends vary from formation to formation, and these variations are attributed to differences in initial grain size and sorting, diagenetic history, and compaction history. In unconsolidated sands, better sorting systematically increases both permeability and porosity. In sands and sandstones, an increase in gravel and coarse grain size content causes k to increase even while decreasing ??. Diagenetic minerals in the pore space of sandstones, such as cement and some clay types, tend to decrease log(k) proportionately as ?? decreases. Models to predict permeability from porosity and other measurable rock parameters fall into three classes based on either grain, surface area, or pore dimension considerations. (Models that directly incorporate well log measurements but have no particular theoretical underpinnings from a fourth class.) Grain-based models show permeability proportional to the square of grain size times porosity raised to (roughly) the fifth power, with grain sorting as an additional parameter. Surface-area models show permeability proportional to the inverse square of pore surface area times porosity raised to (roughly) the fourth power; measures of surface area include irreducible water saturation and nuclear magnetic resonance. Pore-dimension models show permeability proportional to the square of a pore dimension times porosity raised to a power of (roughly) two and produce curves of constant pore size that transgress the linear data trends on a log(k)-?? plot. The pore dimension is obtained from mercury injection measurements and is interpreted as the pore opening size of some interconnected fraction of the pore system. The linear log(k)-?? data trends cut the curves of constant pore size from the pore-dimension models

  5. Gas-solid reaction with porosity change

    Directory of Open Access Journals (Sweden)

    Ivar Stakgold

    2000-10-01

    Full Text Available For a gas diffusing through a porous solid and reacting with it isothermally and irreversibly, the mathematical formulation consists of a nonlinear parabolic PDE for the gas concentration coupled with an ODE for the solid concentration. Under the assumption of constant porosity, a fairly complete analysis was provided by Diaz and Stakgold, [3]. Here some of the results are extended to the case when the porosity increases as the solid is consumed. In particular, estimates are given for the time to full conversion of the solid when the reaction rate is proportional to the product of the gas concentration and a fractional power of the solid concentration.

  6. OpenStax: Microbiology Provides a Cost-Effective and Accessible Resource for Undergraduate Microbiology Students

    Directory of Open Access Journals (Sweden)

    Amanda Lyn Gunn

    2016-05-01

    Full Text Available This is a review of Openstax: Microbiology, a textbook that has been put together by a collaborative effort between Openstax College and the American Society for Microbiology.  The text will be offered in a variety of formats including web-based, PDF, and hardcopy, and is set for publication Spring 2016. Review of: OpenStax: Microbiology. Nina Parker, Mark Schneegurt, and Anh-Hue Tu; (2016. OpenStax and ASM. 1100 pages. (Note: At time of journal printing, this book was not yet published. Certain publication details may change slightly.

  7. Setting-up a European Cross-Provider Data Collection on Open Online Courses

    Science.gov (United States)

    Kalz, Marco; Kreijns, Karel; Walhout, Jaap; Castaño-Munoz, Jonatan; Espasa, Anna; Tovar, Edmundo

    2015-01-01

    While MOOCS have emerged as a new form of open online education around the world, research is stilling lagging behind to come up with a sound theoretical basis that can cover the impact of socio-economic background variables, ICT competences, prior experiences and lifelong learning profile, variance in intentions, environmental influences, outcome…

  8. Open Source Database and Website to Provide Free and Open Access to Inactive U.S. Patents in the Public Domain

    Directory of Open Access Journals (Sweden)

    Yuenyong Nilsiam

    2016-11-01

    Full Text Available Although theoretically the patent system is meant to bolster innovation, the current United States Patent and Trademark Office (USPTO is cumbersome and involves a significant time investment to locate inactive patents less than 20 years old. This article reports on the development of an open source database to find these public domain ideas. First, a search strategy is explained. Then the operation and use of free and open source software are detailed to meet the needs of open hardware innovators. Finally, a case study is presented to demonstrate the utility of the approach with 3-D printing. The results showed how the Free Inactive Patent Search enables users to search using plain language text to find public domain concepts and then provides a hyperlinked list of ideas that takes users to the USPTO database for the patent for more information. All of the source code to operate the search and the website are open source themselves and provided in the public domain for free. In the case study on 3-D printing the time to identify public domain patents was cut by a factor of more than 1500. This tool has the potential for accelerating the development of open hardware technologies to create high value for the public.

  9. Multiple Problem-Solving Strategies Provide Insight into Students' Understanding of Open-Ended Linear Programming Problems

    Science.gov (United States)

    Sole, Marla A.

    2016-01-01

    Open-ended questions that can be solved using different strategies help students learn and integrate content, and provide teachers with greater insights into students' unique capabilities and levels of understanding. This article provides a problem that was modified to allow for multiple approaches. Students tended to employ high-powered, complex,…

  10. Experimental Study on the Porosity Creep Properties of Broken Limestone

    Directory of Open Access Journals (Sweden)

    Li Shun-cai

    2016-01-01

    Full Text Available In the underground engineering, the long-term stability of the surrounding rocks (especially the broken rocks containing water and the ground settlement resulted from the seepage-creep coupling above goaf have been the important research subjects concerning the deep mining. For the broken rock, its porosity is an important structural parameter determining its creep properties, and the porosity change rate is more superior to describe the creep characteristics compared with the strain change rate at a certain direction. In this paper, MTS815.02 Rock Mechanics Test System is used to carry out the creep experiments on water-saturated broken limestone, and then the time curves of porosity and of the porosity change rate are obtained. By regression, we have got the relation equation between the porosity change rate with the instant porosity and the stress level during the creep. The study indicates that when the stress retains a constant level, the relation between the porosity change rate and the instant porosity can be fitted with a cubical polynomial. The obtained creep relation equation between the porosity change rate and the instant porosity and the instant stress provides a necessary state equation for studying the coupling between the seepage and the creep of the broken rock. Furthermore, the seepage in the broken rock has been verified to satisfy the Forchheimer’s non-Darcy flow according to our previous studies, and its seepage properties, k, β and ca can all be expressed respectively as the polynomial of the porosity, so, by combining with these three state equations we have obtained the four essential state equations for solving the coupling problems of the seepage and the creep for the broken rocks.

  11. Open communication: Recommendations for enhancing communication among primary care and mental health providers, services, and systems.

    Science.gov (United States)

    Wong, Shale L; Talmi, Ayelet

    2015-06-01

    Comments on the article "Please break the silence: Parents' views on communication between pediatric primary care and mental health providers" by Greene et al. (see record 2015-14521-001). The article highlights the need to improve communication between primary care and mental health care providers to better serve children and families. The report reaffirms that parents understand the value and necessity of collaborative care, as evidenced by the identification of gaps in consistency of bidirectional communication between providers in traditional and separate practice settings and the desire for improved care coordination. (c) 2015 APA, all rights reserved).

  12. Opening cultural doors: providing culturally sensitive healthcare to Arab American and American Muslim patients.

    Science.gov (United States)

    Hammoud, Maya M; White, Casey B; Fetters, Michael D

    2005-10-01

    Differences in the social and religious cultures of Arab Americans and American Muslims raise challenges to healthcare access and delivery. These challenges go far beyond language to encompass entire world views, concepts of health, illness, and recovery and even death. Medical professionals need a more informed understanding and consideration of the rich and diverse array of beliefs, expectations, preferences, and behavioral make up of the social cultures of these patients to ensure that they are providing the best and most comprehensive care possible. Improved understanding will enhance a provider's ability to offer quality healthcare and to build trusting relationships with patients. Here, we provide a broad overview of Arab culture and Islamic religious beliefs that will assist providers in delivering culturally sensitive healthcare to these groups. We offer insight into the behaviors, requirements, and preferences of Arab American and American Muslim patients, especially as they apply to women's health.

  13. Selective fracturing completion in horizontal open hole provides a new horizon in the Chicontepec Basin

    Energy Technology Data Exchange (ETDEWEB)

    Terrazas, Martin; Huidobro, Efrain [Petroleos Mexicanos (PEMEX), Mexico, DF (Mexico); Bernechea, Jose Maria; Kalinin, Daniel [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    Over the past few years, production has declined in Mexico's main producing field (Cantarell). Because of this decline and increasing oil prices, the operating company has sought to increase oil production from other fields, such as the Chicontepec field, which is located in Veracruz. It is 3,815 k m2 in area and has over 139 billion b bl of original oil in place, from which an estimated 12 billion b bl are recoverable with existing technology. Chicontepec is not naturally as prolific as Cantarell, which forces the operating company and service companies to find new and more creative solutions to unlock the economic potential of this low-permeability basin. Over the past two years, the operating company and the service companies have collaborated to find unconventional solutions to maximize hydrocarbon recovery in Chicontepec. Most recently, the operating company started drilling a multilateral well with two horizontal lateral sections to boost production. After disappointing initial oil rates from the naturally completed open hole section in the first arm, engineers were called upon to design a novel completion and fracturing program that would facilitate multiple propped hydraulic fractures to effectively stimulate the well. Two arms of the multilateral well were stimulated and auspicious results were obtained. Our simulations indicate that commingled production from multiple efficient treatments is the key to unlock Chicontepec potential and change project economics. (author)

  14. AGRIS: providing access to agricultural research data exploiting open data on the web.

    Science.gov (United States)

    Celli, Fabrizio; Malapela, Thembani; Wegner, Karna; Subirats, Imma; Kokoliou, Elena; Keizer, Johannes

    2015-01-01

    AGRIS is the International System for Agricultural Science and Technology. It is supported by a large community of data providers, partners and users. AGRIS is a database that aggregates bibliographic data, and through this core data, related content across online information systems is retrieved by taking advantage of Semantic Web capabilities. AGRIS is a global public good and its vision is to be a responsive service to its user needs by facilitating contributions and feedback regarding the AGRIS core knowledgebase, AGRIS's future and its continuous development. Periodic AGRIS e-consultations, partner meetings and user feedback are assimilated to the development of the AGRIS application and content coverage. This paper outlines the current AGRIS technical set-up, its network of partners, data providers and users as well as how AGRIS's responsiveness to clients' needs inspires the continuous technical development of the application. The paper concludes by providing a use case of how the AGRIS stakeholder input and the subsequent AGRIS e-consultation results influence the development of the AGRIS application, knowledgebase and service delivery.

  15. Processing and properties of Titanium alloy based materials with tailored porosity and composition

    Science.gov (United States)

    Cabezas-Villa, Jose Luis; Olmos, Luis; Lemus-Ruiz, Jose; Bouvard, Didier; Chavez, Jorge; Jimenez, Omar; Manuel Solorio, Victor

    2017-06-01

    This paper deals with powder processing of Ti6Al4V titanium alloy based materials with tailored porosity and composition. Ti6Al4V powder was mixed either with salt particles acting as space holder, so as to provide two-scale porosity, or with hard TiN particles that significantly modified the microstructure of the material and increased its hardness. Finally an original three-layer component was produced. Sample microstructure was observed by SEM and micro-tomography with special interest in pore size and shape, inclusion distribution and connectivity. Compression tests provided elastic modulus and yield stress as functions of density. These materials are representative of bone implants subjected to complex biological and mechanical conditions. These results thus open avenues for processing personalized implants by powder metallurgy.

  16. Data Qualification Report: Calculated Porosity and Porosity-Derived Values for Lithostratigraphic Units for use on the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    P. Sanchez

    2001-05-30

    report uses technical assessment and corroboration to evaluate the original subject DTN. Rael (1999) provides many technical details of the technical assessment and corroboration methods and partially satisfies the intent of the qualification plan for this analysis. Rael presents a modified method based on Nelson (1996) to recompute porosity and porosity-derived values and uses some of the same inputs. Rael's (1999) intended purpose was to document porosity output relatively free of biases introduced by differing computational methods or parameter selections used for different boreholes. The qualification report necessarily evaluates the soundness of the pre-Process Validation and Re-engineering (PVAR) analyses and methodology, as reported in Rael (1999).

  17. Control of Volume and Porosity on Pumice Floatation Time: A Case Study with Pumice from the Havre Submarine Caldera Volcano

    Science.gov (United States)

    Hosseini, B.; Fauria, K.; Manga, M.; Carey, R.; Soule, S. A.

    2016-12-01

    During the 2015 MESH (Mapping, Exploration, and Sampling at Havre) expedition to the submarine Havre caldera volcano, we collected pumice from the 2012 eruption. Here, we report pumice volume, porosity, and floatation time from measurements on 32 clasts (0.2-16 g) that provide insight into the eruption dynamics and mechanisms that deposited these clasts on the seafloor. We measured pumice volume using photogrammetry, capturing 100-180 images per sample. We used a series of open-source software—VisualSFM and MeshLab—to process the images and construct volume models. Combined with measurements of mass, we can determine pumice porosity. We calculated a mean porosity of 0.86+/-0.03 for the 32 samples. The lowest measured porosity of 0.78 was from a fragment of a giant 1.5-m diameter pumice clast. In addition to quantifying pumice volume and porosity, we conducted floatation experiments in which we cleaned, dried, and set the 32 samples on water and measured the time required for each clast to sink. Pumice floatation times varied from 0.8-226 days. We found that pumice floatation time scales with both pumice volume and porosity. These trends are consistent with a gas trapping mechanism for cold pumice floatation and suggest that pumice porosity, in addition to pumice volume, exerts an important control on the floatation time and fate of floating pumice. Despite the wide range of floatation times for these clasts, the proximal to vent collection suggests that these pumice (with the possible exception of the giant pumice fragment) were deposited on the seafloor soon after the 2012 eruption and never reached the ocean surface.

  18. Effects of sintering temperature on the density and porosity

    African Journals Online (AJOL)

    2013-03-01

    Mar 1, 2013 ... perative. Hence the aim of this paper is to critically investi- gate the effects of sintering temperature on the density and porosity of salt bead preforms used in the liquid infiltration of aluminium for open cell foam manufac- turing. 2. Sintering Mechanism. Sintering occurs by atomic diffusion processes that.

  19. Influence of porosity on mechanical properties of tetragonal stabilized zirconia

    DEFF Research Database (Denmark)

    Boccaccini, Dino; Frandsen, Henrik Lund; Soprani, Stefano

    2017-01-01

    3YSZ specimens with variable open porosity (1–57%) were fabricated, and the stiffness, strength and fracture properties (fracture toughness and R-curve) were measured to investigate their potential use as support structures for solid oxide fuel or electrolysis cells. The ball-on-ring test was use...

  20. Effect of paper porosity on OCT images: Monte Carlo study

    Science.gov (United States)

    Kirillin, Mikhail Yu.; Priezzhev, Alexander V.; Myllylä, Risto

    2008-06-01

    Non-invasive measurement of paper porosity is an important problem for papermaking industry. Presently used techniques are invasive and require long time for processing the sample. In recent years optical coherence tomography (OCT) has been proved to be an effective tool for non-invasive study of optically non-uniform scattering media including paper. The aim of present work is to study the potential ability of OCT for sensing the porosity of a paper sample by means of numerical simulations. The paper sample is characterized by variation of porosity along the sample while numerical simulations allow one to consider the samples with constant porosity which is useful for evaluation of the technique abilities. The calculations were performed implementing Monte Carlo-based technique developed earlier for simulation of OCT signals from multilayer paper models. A 9-layer model of paper consisting of five fiber layers and four air layers with non-planar boundaries was considered. The porosity of the samples was varied from 30 to 80% by varying the thicknesses of the layers. The simulations were performed for model paper samples without and with optical clearing agents (benzyl alcohol, 1-pentanol, isopropanol) applied. It was shown that the simulated OCT images of model paper with various porosities significantly differ revealing the potentiality of the OCT technique for sensing the porosity. When obtaining the images of paper samples with optical clearing agents applied, the inner structure of the samples is also revealed providing additional information about the samples under study.

  1. Soil surface roughness and porosity under different tillage systems

    Science.gov (United States)

    Rodriguez-Gonzalez, J.; Saa-Requejo, A.; Gómez, J. A.; Valencia, J. L.; Zarco, P.; Tarquis, A. M.

    2012-04-01

    Both soil porosity and surface elevation can be altered by tillage operation. Even though the surface porosity is an important parameter of a tilled field, however, no practical technique for rapid and non-contact measurement of surface porosity has been developed yet. On the contrary, the surface elevation of tilled soil can be quickly determined with a laser profiler. Working under the assumption that the surface elevation of a tilled field is a complicated superposition of the soil terrain profile at a larger-scale and the roughness at a fine-scale, this study included three aspects: (i) to establish an index (Roughness Index, RI) at a fine-scale to associate the surface roughness with porosity; (ii) to examine the correlation between surface porosity and the proposed RI by three types of tillage treatment in the field; and (iii) to check the scaling/multiscaling behavior among different grid sizes of calculating RI on predicting surface porosity. Consequently, the statistical results from each tilled plot show a strong correlation between the surface porosity and the defined RI in an early stage (ca. 2 days) after tillage. Acknowledgements Funding provided by CEIGRAM (Research Centre for the Management of Agricultural and Environmental Risks)and Spanish Ministerio de Ciencia e Innovación (MICINN) through project AGL2010-21501/AGR is greatly appreciated.

  2. The Wildland Fire Emissions Information System: Providing information for carbon cycle studies with open source geospatial tools

    Science.gov (United States)

    French, N. H.; Erickson, T.; McKenzie, D.

    2008-12-01

    A major goal of the North American Carbon Program is to resolve uncertainties in understanding and managing the carbon cycle of North America. As carbon modeling tools become more comprehensive and spatially oriented, accurate datasets to spatially quantify carbon emissions from fire are needed, and these data resources need to be accessible to users for decision-making. Under a new NASA Carbon Cycle Science project, Drs. Nancy French and Tyler Erickson, of the Michigan Technological University, Michigan Tech Research Institute (MTRI), are teaming with specialists with the USDA Forest Service Fire and Environmental Research Applications (FERA) team to provide information for mapping fire-derived carbon emissions to users. The project focus includes development of a web-based system to provide spatially resolved fire emissions estimates for North America in a user-friendly environment. The web-based Decision Support System will be based on a variety of open source technologies. The Fuel Characteristic Classification System (FCCS) raster map of fuels and MODIS-derived burned area vector maps will be processed using the Geographic Data Abstraction Library (GDAL) and OGR Simple Features Library. Tabular and spatial project data will be stored in a PostgreSQL/PostGIS, a spatially enabled relational database server. The browser-based user interface will be created using the Django web page framework to allow user input for the decision support system. The OpenLayers mapping framework will be used to provide users with interactive maps within the browser. In addition, the data products will be made available in standard open data formats such as KML, to allow for easy integration into other spatial models and data systems.

  3. Supporting diverse data providers in the open water data initiative: Communicating water data quality and fitness of use

    Science.gov (United States)

    Larsen, Sara; Hamilton, Stuart; Lucido, Jessica M.; Garner, Bradley D.; Young, Dwane

    2016-01-01

    Shared, trusted, timely data are essential elements for the cooperation needed to optimize economic, ecologic, and public safety concerns related to water. The Open Water Data Initiative (OWDI) will provide a fully scalable platform that can support a wide variety of data from many diverse providers. Many of these will be larger, well-established, and trusted agencies with a history of providing well-documented, standardized, and archive-ready products. However, some potential partners may be smaller, distributed, and relatively unknown or untested as data providers. The data these partners will provide are valuable and can be used to fill in many data gaps, but can also be variable in quality or supplied in nonstandardized formats. They may also reflect the smaller partners' variable budgets and missions, be intermittent, or of unknown provenance. A challenge for the OWDI will be to convey the quality and the contextual “fitness” of data from providers other than the most trusted brands. This article reviews past and current methods for documenting data quality. Three case studies are provided that describe processes and pathways for effective data-sharing and publication initiatives. They also illustrate how partners may work together to find a metadata reporting threshold that encourages participation while maintaining high data integrity. And lastly, potential governance is proposed that may assist smaller partners with short- and long-term participation in the OWDI.

  4. A Model of Network Porosity

    Science.gov (United States)

    2016-11-09

    standpoint remains more of an art than a science . Even when well executed, the ongoing evolution of the network may violate initial, security-critical design...from a security standpoint remains more of an art than a science . Even when well executed, the ongoing evolution of the network may violate initial...is outside the scope of this paper. As such, we focus on event probabilities. The output of the network porosity model is a stream of timestamped

  5. Brazilian urban porosity : Treat or threat?

    NARCIS (Netherlands)

    Moreno Pessoa, I.; Tasan-Kok, M.T.; Korthals Altes, W.K.

    2016-01-01

    Urban areas have spatial discontinuities, such as disconnected neighbourhoods, brownfield areas and leftover places. They can be captured by the metaphor of urban porosity. This paper aims to highlight the potential social consequences of urban porosity by creating a ‘porosity index’. The authors

  6. Acoustic methods for measuring the porosities of porous materials incorporating dead-end pores.

    Science.gov (United States)

    Dupont, Thomas; Leclaire, Philippe; Panneton, Raymond

    2013-04-01

    The acoustic properties of porous materials containing dead-end (DE) pores have been proposed by Dupont et al. [J. Appl. Phys. 110, 094903 (2011)]. In the theoretical description, two physical parameters were defined (the dead-end porosity and the average length of the dead-end pores). With the knowledge of the open porosity (measured with non-acoustic methods), and the measurement of kinematic porosity (also called the Biot porosity in this article), it is possible to deduce the dead-end porosity. Two acoustic methods for measuring the Biot porosity for a wide range of porosities are proposed. These methods are based on acoustic transmission and on the low and high frequency behaviors of acoustic indicators. The low frequency method is valid for high porosities. It involves measurements in a transmission tube and the knowledge of the theoretical asymptotic behavior of the phase velocity at high frequencies. The high frequency method is based on ultrasonic measurements and on the high frequency asymptotic behavior of the transmission coefficient. It is well adapted for material with relatively low values of porosity. Good precision was found for both methods and materials containing dead end porosity were tested.

  7. OPEN

    DEFF Research Database (Denmark)

    Nickelsen, Anders; Paterno, Fabio; Grasselli, Agnese

    2010-01-01

    One important aspect of ubiquitous environments is to provide users with the possibility to freely move about and continue to interact with the available applications through a variety of interactive devices such as cell phones, PDAs, desktop computers, intelligent watches or digital television...

  8. Effect of Porosity on Particle Erosion Wear Behavior of Lab. Scale SICF/SIC Composites

    Science.gov (United States)

    Suh, Min-Soo; Kohyama, Akira

    The use of silicon-based ceramics and composites as combustor liners and turbine vanes provides the potential of improving next-generation turbine engine performance, through lower emissions and higher cycle efficiency, relative to today's use of super alloy hot-section components. As a series of research for FOD resistant, a particle erosion wear test was carried out for continuous Pre-SiC fiber-reinforced SiC matrix composites with a new concept of lab. scale fabrication by LPS process. The result shows that aperture (some form of porosity) between fiber and interface has a deleterious effect on erosion resistance. Aperture along the fiber interfaces consequently causes a severe wear in the form of fiber detachment. Wear rate increase proportional as contents of open porosity increases. For nearly full dense composite materials of about 0.5 % porosity, are about 200 % more wear-resistant than about 5 % porous composites. Grain growth and consolidate condition of matrix which directly affects to FOD resistant are also discussed.

  9. Effect of SCM on porosity

    DEFF Research Database (Denmark)

    Canut, Mariana

    and connectivity of pores affect durability. Supplementary cementitious materials (SCMs) are being increasingly used as a substitute for Portland cement in the interests of sustainability and to improve the engineering properties of concrete as strength and durability. SCMs are by-products such as slag from iron...... blast furnaces, fly ash from coal fired power stations, and silica fume from ferrosilicon production. Studies suggest that the improvement of the strength and durability using SCMs are governed by refinement of the pores in the cement paste. Both the chemical and physical properties of the SCMs......Pores are an inherent part of cement-based materials. The pores range from nm to cm varying in shape and distribution. The amount, size and distribution of pores affect the engineering properties. As a first approximation, the total porosity affects the mechanical behavior, whereas the size...

  10. Use of Information and Communication Technologies in India's First Open University: Experience and Perceptions of Learners and Learner Support Providers

    Science.gov (United States)

    Satyanarayana, P.; Meduri, Emmanuel D. K.

    2015-01-01

    Dr. B. R. Ambedkar Open University (BRAOU), the first distance teaching university in India, was a great educational event. It started a new chapter in the history of India's distance higher education. The general objects this research studies are: (1) to identify the information and communication technologies used in open distance education…

  11. Determination of the Porosity Surfaces of the Disposal Room Containing Various Waste Inventories for WIPP PA.

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoung; Hansen, Francis D.

    2005-07-01

    This report develops a series of porosity surfaces for the Waste Isolation Pilot Plant. The concept of a porosity surface was developed for performance assessment and comprises calculation of room closure as salt creep processes are mitigated by gas generation and back stress created by the waste packages within the rooms. The physical and mechanical characteristics of the waste packaging that has already been disposed--such as the pipe overpack--and new waste packaging--such as the advanced mixed waste compaction--are appreciably different than the waste form upon which the original compliance was based and approved. This report provides structural analyses of room closure with various waste inventories. All of the underlying assumptions pertaining to the original compliance certification including the same finite element code are implemented; only the material parameters describing the more robust waste packages are changed from the certified baseline. As modeled, the more rigid waste tends to hold open the rooms and create relatively more void space in the underground than identical calculations run on the standard waste packages, which underpin the compliance certification. The several porosity surfaces quantified within this report provide possible ranges of pressure and porosity for performance assessment analyses.3 Intentionally blank4 AcknowledgementsThis research is funded by WIPP programs administered by the U.S. Department of Energy. The authors would like to acknowledge the valuable contributions to this work provided by others. Dr. Joshua S. Stein helped explain the hand off between these finite element porosity surfaces and implementation in the performance calculations. Dr. Leo L. Van Sambeek of RESPEC Inc. helped us understand the concepts of room closure under the circumstances created by a rigid waste inventory. Dr. T. William Thompson and Tom W. Pfeifle provided technical review and Mario J. Chavez provided a Quality Assurance review. The paper

  12. Acoustics of a Mixed Porosity Felt Airfoil

    Science.gov (United States)

    2016-06-06

    NUWC-NPT Technical Report 12,212 6 June 2016 Acoustics of a Mixed Porosity Felt Airfoil Aren M. Hellum Undersea Warfare Weapons...Research project “ Acoustics and Performance of Lifting Surfaces with Mixed Porosity.” The technical reviewer for this report was Dr. Jesse Belden...MM-YYYY) 06-06-2016 2. REPORT TYPE Technical Report 3. DATES COVERED (From – To) 4. TITLE AND SUBTITLE Acoustics of a Mixed Porosity

  13. Measuring tablet porosity using multispectral imaging system

    Science.gov (United States)

    Nippolainen, Ervin; Ervasti, Tuomas; Ketolainen, Jarkko; Kamshilin, Alexei A.

    2010-05-01

    A multispectral imaging system with computer controlled light source of 16 light emitting diodes is applied for measuring of tablet porosity. The system is based on a subspace vector model of surface reflection. The measured spectral data are compressed on the stage of measurement and used directly for the discrimination of tablets with different porosity. The experimental results demonstrate that the multispectral imaging system is a potential method for tablet porosity measurement.

  14. Flow dynamics of dacite lava flow - AMS, microstructure and porosity case study

    Science.gov (United States)

    Závada, Prokop; Kusbach, Vladimír; Machek, Matěj; Staněk, Martin; Špičák, Aleš

    2017-04-01

    -size distribution corresponds to four distinct intervals reflected by: (I) distributed porosity in matrix (0.02-0.1 µm), (II) microcracks in matrix and microfractures in the phenocrysts (0.4-2 µm), (III) larger microcracks in matrix that likely represent coalesced microcracks (3-10 µm) and (IV) large microcracks (10-300 µm), including the macroscopic, irregular openings in the matrix and in the vicinity of the clasts/phenocrysts. The highest porosity characterizes the layer C which, unlike the other layers, features important porosity (up to 5 %) accessible by large (10-300 µm) pore throats corresponding to class IV. Results of the MIP measurements of the bulk and the mineralogical densities suggest that an important part (40%) of the total porosity is isolated and becomes progressively connected with the increasing volume of microcracks. Data suggests that the abundant shear fractures oriented at high angles to shear planes developed as mechanical instabilities during the flow, propagated in distinct layers and were modified to sigmoidal fractures. The dilatancy provides the „shear thickening rheology" and likely plays a significant role in frontal collapse of crystal-rich lava flows.

  15. The steady aerodynamics of aerofoils with porosity gradients

    Science.gov (United States)

    Hajian, Rozhin; Jaworski, Justin W.

    2017-09-01

    This theoretical study determines the aerodynamic loads on an aerofoil with a prescribed porosity distribution in a steady incompressible flow. A Darcy porosity condition on the aerofoil surface furnishes a Fredholm integral equation for the pressure distribution, which is solved exactly and generally as a Riemann-Hilbert problem provided that the porosity distribution is Hölder-continuous. The Hölder condition includes as a subset any continuously differentiable porosity distributions that may be of practical interest. This formal restriction on the analysis is examined by a class of differentiable porosity distributions that approach a piecewise, discontinuous function in a certain parametric limit. The Hölder-continuous solution is verified in this limit against analytical results for partially porous aerofoils in the literature. Finally, a comparison made between the new theoretical predictions and experimental measurements of SD7003 aerofoils presented in the literature. Results from this analysis may be integrated into a theoretical framework to optimize turbulence noise suppression with minimal impact to aerodynamic performance.

  16. The steady aerodynamics of aerofoils with porosity gradients.

    Science.gov (United States)

    Hajian, Rozhin; Jaworski, Justin W

    2017-09-01

    This theoretical study determines the aerodynamic loads on an aerofoil with a prescribed porosity distribution in a steady incompressible flow. A Darcy porosity condition on the aerofoil surface furnishes a Fredholm integral equation for the pressure distribution, which is solved exactly and generally as a Riemann-Hilbert problem provided that the porosity distribution is Hölder-continuous. The Hölder condition includes as a subset any continuously differentiable porosity distributions that may be of practical interest. This formal restriction on the analysis is examined by a class of differentiable porosity distributions that approach a piecewise, discontinuous function in a certain parametric limit. The Hölder-continuous solution is verified in this limit against analytical results for partially porous aerofoils in the literature. Finally, a comparison made between the new theoretical predictions and experimental measurements of SD7003 aerofoils presented in the literature. Results from this analysis may be integrated into a theoretical framework to optimize turbulence noise suppression with minimal impact to aerodynamic performance.

  17. Designed porosity materials in nuclear reactor components

    Science.gov (United States)

    Yacout, A. M.; Pellin, Michael J.; Stan, Marius

    2016-09-06

    A nuclear fuel pellet with a porous substrate, such as a carbon or tungsten aerogel, on which at least one layer of a fuel containing material is deposited via atomic layer deposition, and wherein the layer deposition is controlled to prevent agglomeration of defects. Further, a method of fabricating a nuclear fuel pellet, wherein the method features the steps of selecting a porous substrate, depositing at least one layer of a fuel containing material, and terminating the deposition when the desired porosity is achieved. Also provided is a nuclear reactor fuel cladding made of a porous substrate, such as silicon carbide aerogel or silicon carbide cloth, upon which layers of silicon carbide are deposited.

  18. Opening Minds Stigma Scale for Health Care Providers (OMS-HC): Examination of psychometric properties and responsiveness

    Science.gov (United States)

    2014-01-01

    Background Diminishing stigmatization for those with mental illnesses by health care providers (HCPs) is becoming a priority for programming and policy, as well as research. In order to be successful, we must accurately measure stigmatizing attitudes and behaviours among HCPs. The Opening Minds Stigma Scale for Health Care Providers (OMS-HC) was developed to measure stigma in HCP populations. In this study we revisit the factor structure and the responsiveness of the OMS-HC in a larger, more representative sample of HCPs that are more likely to be targets for anti-stigma interventions. Methods Baseline data were collected from HCPs (n = 1,523) during 12 different anti-stigma interventions across Canada. The majority of HCPs were women (77.4%) and were either physicians (MDs) (41.5%), nurses (17.0%), medical students (13.4%), or students in allied health programs (14.0%). Exploratory factor analysis (EFA) was conducted using complete pre-test (n = 1,305) survey data and responsiveness to change analyses was examined with pre and post matched data (n = 803). The internal consistency of the OMS-HC scale and subscales was evaluated using the Cronbach’s alpha coefficient. The scale’s sensitivity to change was examined using paired t-tests, effect sizes (Cohen’s d), and standardized response means (SRM). Results The EFA favored a 3-factor structure which accounted for 45.3% of the variance using 15 of 20 items. The overall internal consistency for the 15-item scale (α = 0.79) and three subscales (α = 0.67 to 0.68) was acceptable. Subgroup analysis showed the internal consistency was satisfactory across HCP groups including physicians and nurses (α = 0.66 to 0.78). Evidence for the scale’s responsiveness to change occurred across multiple samples, including student-targeted interventions and workshops for practicing HCPs. The Social Distance subscale had the weakest level of responsiveness (SRM ≤ 0.50) whereas the more attitudinal

  19. Procedure for Uranium-Molybdenum Density Measurements and Porosity Determination

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-08-13

    The purpose of this document is to provide guidelines for preparing uranium-molybdenum (U-Mo) specimens, performing density measurements, and computing sample porosity. Typical specimens (solids) will be sheared to small rectangular foils, disks, or pieces of metal. A mass balance, solid density determination kit, and a liquid of known density will be used to determine the density of U-Mo specimens using the Archimedes principle. A standard test weight of known density would be used to verify proper operation of the system. By measuring the density of a U-Mo sample, it is possible to determine its porosity.

  20. Fabrication of (U,Am)O2 pellet with controlled porosity from oxide microspheres

    Science.gov (United States)

    Ramond, Laure; Coste, Philippe; Picart, Sébastien; Gauthé, Aurélie; Bataillea, Marc

    2017-08-01

    U1-xAmxO2±δ mixed-oxides are considered as promising compounds for americium heterogeneous transmutation in Sodium Fast Neutron Reactor. Porous microstructure is envisaged in order to facilitate helium and fission gas release and to reduce pellet swelling during irradiation and under self-irradiation. In this study, the porosity is created by reducing (U,Am)3O8 microspheres into (U,Am)O2 during the sintering. This reduction is accompanied by a decrease of the lattice volume that leads to the creation of open porosity. Finally, an (U0.90Am0.10)O2 porous ceramic pellet (D∼89% of the theoretical density TD) with controlled porosity (≥8% open porosity) was obtained from mixed-oxide microspheres obtained by the Weak Acid Resin (WAR) process.

  1. Porosity Prediction of Plain Weft Knitted Fabrics

    Directory of Open Access Journals (Sweden)

    Muhammad Owais Raza Siddiqui

    2014-12-01

    Full Text Available Wearing comfort of clothing is dependent on air permeability, moisture absorbency and wicking properties of fabric, which are related to the porosity of fabric. In this work, a plug-in is developed using Python script and incorporated in Abaqus/CAE for the prediction of porosity of plain weft knitted fabrics. The Plug-in is able to automatically generate 3D solid and multifilament weft knitted fabric models and accurately determine the porosity of fabrics in two steps. In this work, plain weft knitted fabrics made of monofilament, multifilament and spun yarn made of staple fibers were used to evaluate the effectiveness of the developed plug-in. In the case of staple fiber yarn, intra yarn porosity was considered in the calculation of porosity. The first step is to develop a 3D geometrical model of plain weft knitted fabric and the second step is to calculate the porosity of the fabric by using the geometrical parameter of 3D weft knitted fabric model generated in step one. The predicted porosity of plain weft knitted fabric is extracted in the second step and is displayed in the message area. The predicted results obtained from the plug-in have been compared with the experimental results obtained from previously developed models; they agreed well.

  2. Reflectance analysis of porosity gradient in nanostructured silicon layers

    Science.gov (United States)

    Jurečka, Stanislav; Imamura, Kentaro; Matsumoto, Taketoshi; Kobayashi, Hikaru

    2017-12-01

    In this work we study optical properties of nanostructured layers formed on silicon surface. Nanostructured layers on Si are formed in order to reach high suppression of the light reflectance. Low spectral reflectance is important for improvement of the conversion efficiency of solar cells and for other optoelectronic applications. Effective method of forming nanostructured layers with ultralow reflectance in a broad interval of wavelengths is in our approach based on metal assisted etching of Si. Si surface immersed in HF and H2O2 solution is etched in contact with the Pt mesh roller and the structure of the mesh is transferred on the etched surface. During this etching procedure the layer density evolves gradually and the spectral reflectance decreases exponentially with the depth in porous layer. We analyzed properties of the layer porosity by incorporating the porosity gradient into construction of the layer spectral reflectance theoretical model. Analyzed layer is splitted into 20 sublayers in our approach. Complex dielectric function in each sublayer is computed by using Bruggeman effective media theory and the theoretical spectral reflectance of modelled multilayer system is computed by using Abeles matrix formalism. Porosity gradient is extracted from the theoretical reflectance model optimized in comparison to the experimental values. Resulting values of the structure porosity development provide important information for optimization of the technological treatment operations.

  3. Fabrication of dual porosity electrode structure

    Science.gov (United States)

    Smith, J.L.; Kucera, E.H.

    1991-02-12

    A substantially entirely fibrous ceramic is described which may have dual porosity of both micro and macro pores. Total porosity may be 60-75% by volume. A method of spraying a slurry perpendicularly to an ambient stream of air is disclosed along with a method of removing binders without altering the fiber morphology. Adding fine ceramic particulates to the green ceramic fibers enhances the sintering characteristics of the fibers. 3 figures.

  4. Simulating a Range of Regolith Porosities in the Lab: An Investigation into the Effects of Porosity on Spectral Measurements of Olivine

    Science.gov (United States)

    Evans, R.; Bowles, N. E.; Donaldson Hanna, K. L.

    2016-12-01

    Our current understanding of the composition of planetary bodies primarily comes from remote sensing spectroscopic observations. The interpretation of spectroscopic data requires analogue mineral spectra measured in the lab under appropriate environmental conditions.This is particularly true in the thermal infrared. At these wavelengths porosity, particle size, and near-surface environmental conditions have significant effects on the wavelength position and spectral contrast of diagnostic features. To isolate the effects due to porosity, diffuse reflectance measurements were made from 2.5 to 25 µm of a fine particulate San Carlos olivine sample (University of Oxford's Simulated Lunar Environment Chamber. When measured in diffuse reflectance, we find that as the porosity increases the Christiansen feature (CF, a reflection minimum or emissivity maximum near 8 µm) shifts to longer wavelengths. In the thermal emissivity spectral measurements, we see no discernible shift in the CF position as the porosity changes. In both reflectance and emission the strength and position of the transparency feature (the spectral region from 11 to 13 µm where volume scattering dominates) behaves as expected, as the strength of the feature increases with porosity. In reflectance the relative strength of the reststrahlen bands (RB) were not observed to change systematically with porosity. In this presentation we provide details of our experimental set-up, the range of porosities simulated in the lab, and our spectroscopic results. These new measurements place important constraints for interpreting remote sensing measurements of planetary bodies.

  5. A Novel Porosity Model for Use in Hydrocode Simulations

    Science.gov (United States)

    Wuennemann, K.; Collins, G. S.; Melosh, H. J.

    2005-01-01

    Introduction: Numerical modeling of impact cratering has reached a high degree of sophistication; however, the treatment of porous materials still poses a large problem in hydrocode calculations. Porosity plays only a minor role in the formation of large craters on most planetary objects, but impacts on comets are believed to be highly affected by the presence of porosity, which may be as much as 80%. The upcoming Deep Impact Mission (launched January 2005) will provide more detailed data about the composition of a comet (Tempel 1) by shooting a approx.370 kg projectile onto the surface of its nucleus. The numerical simulations of such impact events requires an appropriate model for how pore space in the comet is crushed out during the violent initial stage of the impact event. Most hydro-codes compute the pressure explicitly using an "equation of state" (EOS) for each material, which relates changes in density and internal energy to changes in pressure. The added complication introduced by porosity is that changes in a material s density are due to both the closing of pore space (compaction) and compression of the matrix. The amount of resistance to volume change and the amount of irreversible work done during these two processes is very different; it is far easier to compact a porous material sample than to compress a non-porous sample of the same material. As an alternative to existing porosity models, like the Pdot(alpha) model [1], we present a novel approach for dealing with the compaction of porosity in hydrocode calculations.

  6. Quantifying porosity, compressibility and permeability in Shale

    DEFF Research Database (Denmark)

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Frykman, Peter

    The Fjerritslev Formation in the Norwegian-Danish Basin forms the main seal to Upper Triassic-Lower Jurassic sandstone reservoirs. In order to estimate rock properties Jurassic shale samples from deep onshore wells in Danish basin were studied. Mineralogical analysis based on X-ray diffractometry...... (XRD) of shale samples show about 50% silt and high content of kaolinite in the clay fraction when compared with offshore samples from the Central Graben. Porosity measurements from helium porosimetry-mercury immersion (HPMI), mercury injection capillary pressure (MICP) and nuclear magnetic resonance...... (NMR) show that, the MICP porosity is 9-10% points lower than HPMI and NMR porosity. Compressibility result shows that deep shale is stiffer in situ than normally assumed in geotechnical modelling and that static compressibility corresponds with dynamic one only at the begining of unloading stress...

  7. Plant fibre composites - porosity and stiffness

    DEFF Research Database (Denmark)

    Madsen, Bo; Thygesen, Anders; Lilholt, Hans

    2009-01-01

    Plant fibre composites contain typically a relatively large amount of porosity which influences their performance. A model, based on a modified rule of mixtures, is presented to include the influence of porosity on the composite stiffness. The model integrates the volumetric composition...... of the composites with their mechanical properties. The fibre weight fraction is used as an independent parameter to calculate the complete volumetric composition. A maximum obtainable stiffness of the composites is calculated at a certain transition fibre weight fraction, which is characterised by a best possible...... combination of high fibre volume fraction and low porosity. The model is validated with experimental data from the literature on several types of composites. A stiffness diagram is presented to demonstrate that the calculations can be used for tailoring and design of composites with a given profile...

  8. Remaining porosity and permeability of compacted crushed rock salt backfill in a HLW repository. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jobmann, M.; Mueller, C.; Schirmer, S.

    2015-11-15

    The safe containment of radioactive waste is to be ensured by the geotechnical barriers in combination with the containment-providing rock zone (CRZ). The latter is a key element of the recently developed concept of demonstrating the integrity of the geologic barrier (Krone et al., 2013). As stipulated in the safety requirements of the regulating body the CRZ has to have strong barrier properties, and evidence needs to be provided that it retains its integrity throughout the reference period (BMU, 2010). The underground openings excavated in the rock salt will close over time due to the creep properties of the rock salt. This process causes deformations in the surrounding rock salt, which leads to a change in stress state in the virgin rock and may impair the integrity of the containment-providing rock zone. In order to limit the effects of these processes, all underground openings will be backfilled with crushed salt. Immediately after backfilling, the crushed salt will have an initial porosity of approx. 35%, which - over time - will be reduced to very low values due to the creep properties of the rock salt. The supporting pressure that builds up in the crushed salt with increasing compaction slows down the creeping of the salt. Major influencing factors are the temperature (with higher temperatures accelerating the salt creeping) and the moisture of the salt, which - due to the related decrease in the resistance of the crushed salt - facilitates its compaction. The phenomenology of these processes and dependencies is understood to a wide extent. This project investigated the duration until compaction is completed and when and under what circumstances the crushed salt will have the sealing properties necessary to ensure safe containment. Thermo-hydro-mechanical (THM) processes play a crucial role in determining whether solutions which might enter the mine could reach the radioactive waste. This includes changes in material behaviour due to a partial or complete

  9. High-porosity Cenozoic carbonate rocks of South Florida: Progressive loss of porosity with depth

    Science.gov (United States)

    Halley, Robert B.; Schmoker, James W.

    1983-01-01

    Porosity measurements by borehole gravity meter in subsurface Cenozoic carbonates of south Florida reveal an extremely porous mass of limestone and dolomite which is transitional in total pore volume between typical porosity values for modern carbonate sediments and ancient carbonate rocks. A persistent decrease of porosity with depth, similar to that of chalks of the Gulf Coast, occurs in these rocks. We make no attempt to differentiate depositional or diagenetic facies which produce scatter in the porosity-depth relationship; the dominant data trends thus are functions of carbonate rocks in general rather than of particular carbonate facies. Carbonate strata with less than 20% porosity are absent from the rocks studied here.Aquifers and aquicludes cannot be distinguished on the basis of porosity. Although aquifers are characterized by great permeability and well-developed vuggy and even cavernous porosity in some intervals, they are not exceptionally porous when compared to other Tertiary carbonate rocks in south Florida. Permeability in these strata is governed more by the spacial distribution of pore space and matrix than by the total volume of porosity present.Dolomite is as porous as, or slightly less porous than, limestones in these rocks. This observation places limits on any model proposed for dolomitization and suggests that dolomitization does not take place by a simple ion-for-ion replacement of magnesium for calcium. Dolomitization may be selective for less porous limestone, or it may involve the incorporation of significant amounts of carbonate as well as magnesium into the rock.The great volume of pore space in these rocks serves to highlight the inefficiency of early diagenesis in reducing carbonate porosity and to emphasize the importance of later porosity reduction which occurs during the burial or late near-surface history of limestones and dolomites.

  10. Use of the TRPV1 Agonist Capsaicin to Provide Long-Term Analgesia in a Rat Limb Fracture/Open Repair, Internal Fixation Model

    Science.gov (United States)

    2011-10-01

    been no published works evaluating the efficacy of locally applied capsaicin for analgesia in fracture pain or its effects on bone healing and local...term analgesia for postsurgical pain after total knee arthroplasty. Pain Med 10 (2005): 1. 9. Diamond E, Richards PT, Miller T. ALGRX 4975 reduces...Provide Long-Term Analgesia in a Rat Limb Fracture/Open Repair, Internal Fixation Model PRINCIPAL INVESTIGATOR: Michael J. Buys, M.D

  11. Optimization and Development of Swellable Controlled Porosity ...

    African Journals Online (AJOL)

    Purpose: To develop swellable controlled porosity osmotic pump tablet of theophylline and to define the formulation and process variables responsible for drug release by applying statistical optimization technique. Methods: Formulations were prepared based on Taguchi Orthogonal Array design and Fraction Factorial ...

  12. Acoustic properties of double-porosity granular polymers

    Science.gov (United States)

    Alevizaki, A.; Sainidou, R.; Rembert, P.; Morvan, B.; Stefanou, N.

    2017-06-01

    Using an extension of the full elastodynamic layer-multiple-scattering method to structures of fluid-saturated poroelastic spherical bodies, a comprehensive theoretical study of the acoustic response of double-porosity submerged liquid-saturated granular polymeric materials of specific morphology consisting of touching porous polymer spheres arranged in a fcc lattice, beyond the long-wavelength effective-medium description, is presented. Calculated transmission and absorption spectra of finite slabs of these materials are analyzed by reference to the acoustic modes of the constituent porous spherical grains as well as to relevant dispersion diagrams of corresponding infinite crystals, and a consistent interpretation of the results is provided. In particular, it is shown that resonant modes with very long lifetime, localized in the spheres in the form of slow longitudinal waves, which are peculiar to poroelastic materials, are formed when the viscous length is much shorter than the radius of the inner pores of the spheres. These modes, which can be easily tuned in frequency by adjusting the intrinsic porosity of the spheres, induce some remarkable features in the acoustic behavior of these double-porosity materials, such as narrow dispersionless absorption bands and directional transmission gaps.

  13. Modeling flow in porous media with double porosity/permeability: Mathematical model, properties, and analytical solutions

    CERN Document Server

    Nakshatrala, K B; Ballarini, R

    2016-01-01

    Geo-materials such as vuggy carbonates are known to exhibit multiple spatial scales. A common manifestation of spatial scales is the presence of (at least) two different scales of pores, which is commonly referred to as double porosity. To complicate things, the pore-network at each scale exhibits different permeability, and these networks are connected through fissure and conduits. Although some models are available in the literature, they lack a strong theoretical basis. This paper aims to fill this lacuna by providing the much needed theoretical foundations of the flow in porous media which exhibit double porosity/permeability. We first obtain a mathematical model for double porosity/permeability using the maximization of rate of dissipation hypothesis, and thereby providing a firm thermodynamic underpinning. We then present, along with mathematical proofs, several important mathematical properties that the solutions to the double porosity/permeability model satisfy. These properties are important in their...

  14. APPROPRIATE MODELS FOR SIMULATING OPEN-POROUS MATERIALS

    Directory of Open Access Journals (Sweden)

    Tomasz Wejrzanowski

    2017-06-01

    Full Text Available In the present paper two representative models applied for modeling of two types of porous materials - open-cell foams and open-porosity tapes - are addressed. Algorithms presented here base on Laguerre-Voronoi tessellations (open-cell foams and the sphere representation (open-porosity tapes and enable creating the desired porosity and pore size distribution. The geometrical features of the models, such as: porosity, mean pore size, cell diameter distribution and number of faces per cell were compared with those obtained by 3D micro-computed tomography and good agreement was obtained.

  15. The development and psychometric properties of a new scale to measure mental illness related stigma by health care providers: The opening minds scale for Health Care Providers (OMS-HC)

    Science.gov (United States)

    2012-01-01

    Background Research on the attitudes of health care providers towards people with mental illness has repeatedly shown that they may be stigmatizing. Many scales used to measure attitudes towards people with mental illness that exist today are not adequate because they do not have items that relate specifically to the role of the health care provider. Methods We developed and tested a new scale called the Opening Minds Scale for Health Care Providers (OMS-HC). After item-pool generation, stakeholder consultations and content validation, focus groups were held with 64 health care providers/trainees and six people with lived experience of mental illness to develop the scale. The OMS-HC was then tested with 787 health care providers/trainees across Canada to determine its psychometric properties. Results The initial testing OMS-HC scale showed good internal consistency, Cronbach’s alpha = 0.82 and satisfactory test-retest reliability, intraclass correlation = 0.66 (95% CI 0.54 to 0.75). The OMC-HC was only weakly correlated with social desirability, indicating that the social desirability bias was not likely to be a major determinant of OMS-HC scores. A factor analysis favoured a two-factor structure which accounted for 45% of the variance using 12 of the 20 items tested. Conclusions The OMS–HC provides a good starting point for further validation as well as a tool that could be used in the evaluation of programs aimed at reducing mental illness related stigma by health care providers. The OMS-HC incorporates various dimensions of stigma with a modest number of items that can be used with busy health care providers. PMID:22694771

  16. The development and psychometric properties of a new scale to measure mental illness related stigma by health care providers: The opening minds scale for Health Care Providers (OMS-HC

    Directory of Open Access Journals (Sweden)

    Kassam Aliya

    2012-06-01

    Full Text Available Abstract Background Research on the attitudes of health care providers towards people with mental illness has repeatedly shown that they may be stigmatizing. Many scales used to measure attitudes towards people with mental illness that exist today are not adequate because they do not have items that relate specifically to the role of the health care provider. Methods We developed and tested a new scale called the Opening Minds Scale for Health Care Providers (OMS-HC. After item-pool generation, stakeholder consultations and content validation, focus groups were held with 64 health care providers/trainees and six people with lived experience of mental illness to develop the scale. The OMS-HC was then tested with 787 health care providers/trainees across Canada to determine its psychometric properties. Results The initial testing OMS-HC scale showed good internal consistency, Cronbach’s alpha = 0.82 and satisfactory test-retest reliability, intraclass correlation = 0.66 (95% CI 0.54 to 0.75. The OMC-HC was only weakly correlated with social desirability, indicating that the social desirability bias was not likely to be a major determinant of OMS-HC scores. A factor analysis favoured a two-factor structure which accounted for 45% of the variance using 12 of the 20 items tested. Conclusions The OMS–HC provides a good starting point for further validation as well as a tool that could be used in the evaluation of programs aimed at reducing mental illness related stigma by health care providers. The OMS-HC incorporates various dimensions of stigma with a modest number of items that can be used with busy health care providers.

  17. Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

    Science.gov (United States)

    Zou, C.; Marrow, T. J.; Reinhard, C.; Li, B.; Zhang, C.; Wang, S.

    2016-03-01

    The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a "node-bond" geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1~ 9.3% closed micropores.

  18. Air filled porosity in composting processes

    Energy Technology Data Exchange (ETDEWEB)

    Ruggieri, L.; Gea, T.; Artola, A.; Sanchez, A.

    2009-07-01

    As it is widely known, the composting process consists in the aerobic decomposition of the biodegradable organic matter present in different types of solid wastes. Water and oxygen are necessary for the biological activity of microorganisms involved in the composting process and their availability is directly related to the total and the air filled porosity (AFP). Maintaining adequate AFP level satisfies the oxygen content requirement to achieve the desired composting conditions and thus, tho enhance biological activity. (Author)

  19. Soil plasticity with a different porosity

    Directory of Open Access Journals (Sweden)

    Klovanych Sergii

    2017-01-01

    Full Text Available The model of soils with different porosity in the framework of the associated theory of plasticity is presented The single analytical function describes the loading surface in the stress space. The deformational hardening/softening and the phenomenon of dilatancy during plastic flow are incorporated in the model. The triaxial compression tests are simulated and compared with the experimental results for different values of the void ratio and initial hydrostatic stresses.

  20. Mathematical aspects of multi-porosity continua

    CERN Document Server

    Straughan, Brian

    2017-01-01

    This book is devoted to describing theories for porous media where such pores have an inbuilt macro structure and a micro structure. For example, a double porosity material has pores on a macro scale, but additionally there are cracks or fissures in the solid skeleton. The actual body is allowed to deform and thus the underlying theory is one of elasticity. Various different descriptions are reviewed. Chapter 1 introduces the classical linear theory of elastodynamics together with uniqueness and continuous dependence results. Chapters 2 and 3 review developments of theories for double and triple porosity using a pressure-displacement structure and also using voids-displacement. Chapter 4 compares various aspects of the pressure-displacement and voids-displacement theories via uniqueness studies and wave motion analysis. Mathematical analyses of double and triple porosity materials are included concentrating on uniqueness and stability studies in chapters 5 to 7. In chapters 8 and 9 the emphasis is on wa...

  1. Characterization of porosity via secondary reactions. Final technical report, 1 September 1991--30 November 1995

    Energy Technology Data Exchange (ETDEWEB)

    Calo, J.M.; Zhang, L.; Hall, P.J.; Antxustegi, M. [Brown Univ., Providence, RI (United States). Div. of Engineering

    1997-09-01

    A new approach to the study of porosity and porosity development in coal chars during gasification was investigated. This approach involves the establishment of the relationships between the amount and type of surface complexes evolved during post-activation temperature programmed desorption (TPD), and the porosity, as measured by gas adsorption and small angle neutron scattering (SANS) techniques. With this new method, the total surface area and micropore volume can be determined by the interpretation of post-activation TPD spectra. The primary conclusion of this work is that it is possible to predict total surface area and micropore volume from TPD spectra. From the extended random pore model, additional information about the micropore surface area, the nonmicroporous surface area, and the mean micropore size development as a function of reaction time (or burn-off) can also be predicted. Therefore, combining the TPD technique and the extended random pore model provides a new method for the characterization of char porosity.

  2. Monte Carlo Study on Gas Pressure Response of He-3 Tube in Neutron Porosity Logging

    Directory of Open Access Journals (Sweden)

    TIAN Li-li;ZHANG Feng;WANG Xin-guang;LIU Jun-tao

    2016-10-01

    Full Text Available Thermal neutrons are detected by (n,p reaction of Helium-3 tube in the compensated neutron logging. The helium gas pressure in the counting area influences neutron detection efficiency greatly, and then it is an important parameter for neutron porosity measurement accuracy. The variation law of counting rates of a near detector and a far one with helium gas pressure under different formation condition was simulated by Monte Carlo method. The results showed that with the increasing of helium pressure the counting rate of these detectors increased firstly and then leveled off. In addition, the neutron counting rate ratio and porosity sensitivity increased slightly, the porosity measurement error decreased exponentially, which improved the measurement accuracy. These research results can provide technical support for selecting the type of Helium-3 detector in developing neutron porosity logging.

  3. Assessing treatment-as-usual provided to control groups in adherence trials: Exploring the use of an open-ended questionnaire for identifying behaviour change techniques.

    Science.gov (United States)

    Oberjé, Edwin J M; Dima, Alexandra L; Pijnappel, Frank J; Prins, Jan M; de Bruin, Marijn

    2015-01-01

    Reporting guidelines call for descriptions of control group support in equal detail as for interventions. However, how to assess the active content (behaviour change techniques (BCTs)) of treatment-as-usual (TAU) delivered to control groups in trials remains unclear. The objective of this study is to pre-test a method of assessing TAU in a multicentre cost-effectiveness trial of an HIV-treatment adherence intervention. HIV-nurses (N = 21) completed a semi-structured open-ended questionnaire enquiring about TAU adherence counselling. Two coders independently coded BCTs. Completeness and clarity of nurse responses, inter-coder reliabilities and the type of BCTs reported were examined. The clarity and completeness of nurse responses were adequate. Twenty-three of the 26 identified BCTs could be reliably coded (mean κ = .79; mean agreement rate = 96%) and three BCTs scored below κ = .60. Total number of BCTs reported per nurse ranged between 7 and 19 (M = 13.86, SD = 3.35). This study suggests that the TAU open-ended questionnaire is a feasible and reliable tool to capture active content of support provided to control participants in a multicentre adherence intervention trial. Considerable variability in the number of BCTs provided to control patients was observed, illustrating the importance of reliably collecting and accurately reporting control group support.

  4. Condensation Enhancement by Surface Porosity: Three-Stage Mechanism.

    Science.gov (United States)

    Yarom, Michal; Marmur, Abraham

    2015-08-18

    Surface defects, such as pores, cracks, and scratches, are naturally occurring and commonly found on solid surfaces. However, the mechanism by which such imperfections promote condensation has not been fully explored. In the current paper we thermodynamically analyze the ability of surface porosity to enhance condensation on a hydrophilic solid. We show that the presence of a surface-embedded pore brings about three distinct stages of condensation. The first is capillary condensation inside the pore until it is full. This provides an ideal hydrophilic surface for continuing the condensation. As a result, spontaneous condensation and wetting can be achieved at lower vapor pressure than on a smooth surface.

  5. Influence of Chemical Composition on Porosity in Aluminium Alloys

    OpenAIRE

    Kucharčík L.; Brůna M.; Sládek A.

    2014-01-01

    Porosity is one of the major defects in aluminum castings, which results is a decrease of a mechanical properties. Porosity in aluminum alloys is caused by solidification shrinkage and gas segregation. The final amount of porosity in aluminium castings is mostly influenced by several factors, as amount of hydrogen in molten aluminium alloy, cooling rate, melt temperature, mold material, or solidification interval. This article deals with effect of chemical composition on porosity in Al-Si alu...

  6. Mechanical properties and porosity of polylactide for biomedical applications

    NARCIS (Netherlands)

    Sawalha, H.I.M.; Schroën, C.G.P.H.; Boom, R.M.

    2008-01-01

    In this study, the strength, ductility, and porosity of polylactide films prepared by immersion precipitation and film casting in air were investigated. To induce extra porosity in the films, dodecane was added to the polymer casting solution. The structure, porosity, and mechanical properties of

  7. UNESCO's HOPE Initiative—Providing Free and Open-Source Hydrologic Software for Effective and Sustainable Management of Africa's Water Resources Temporary Title

    Science.gov (United States)

    Barlow, P. M.; Filali-Meknassi, Y.; Sanford, W. E.; Winston, R. B.; Kuniansky, E.; Dawson, C.

    2015-12-01

    UNESCO's HOPE Initiative—the Hydro Free and (or) Open-source Platform of Experts—was launched in June 2013 as part of UNESCO's International Hydrological Programme. The Initiative arose in response to a recognized need to make free and (or) open-source water-resources software more widely accessible to Africa's water sector. A kit of software is being developed to provide African water authorities, teachers, university lecturers, and researchers with a set of programs that can be enhanced and (or) applied to the development of efficient and sustainable management strategies for Africa's water resources. The Initiative brings together experts from the many fields of water resources to identify software that might be included in the kit, to oversee an objective process for selecting software for the kit, and to engage in training and other modes of capacity building to enhance dissemination of the software. To date, teams of experts from the fields of wastewater treatment, groundwater hydrology, surface-water hydrology, and data management have been formed to identify relevant software from their respective fields. An initial version of the HOPE Software Kit was released in late August 2014 and consists of the STOAT model for wastewater treatment developed by the Water Research Center (United Kingdom) and the MODFLOW-2005 model for groundwater-flow simulation developed by the U.S. Geological Survey. The Kit is available on the UNESCO HOPE website (http://www.hope-initiative.net/).Training in the theory and use of MODFLOW-2005 is planned in southern Africa in conjunction with UNESCO's study of the Kalahari-Karoo/Stampriet Transboundary Aquifer, which extends over an area that includes parts of Botswana, Namibia, and South Africa, and in support of the European Commission's Horizon 2020 FREEWAT project (FREE and open source software tools for WATer resource management; see the UNESCO HOPE website).

  8. Generating Porosity in the Critical Zone: Does Volumetric Strain Dominate Chemical Mass Loss?

    Science.gov (United States)

    Hayes, J. L.; Riebe, C. S.; Holbrook, W. S.; Hartsough, P. C.

    2015-12-01

    The opening of pore space by weathering near Earth's surface influences a broad array of hydrological and biogeochemical processes, including water storage, surface-groundwater interactions, and nutrient cycling. Understanding how porosity is generated by physical and chemical processes is therefore a fundamental challenge in critical zone science. However, the relative importance and spatial variability of mechanisms that generate porosity remain poorly understood, because the subsurface is hidden from direct observation except by drilling and geophysical measurements. Here we use observations from both drilling and geophysics to quantify the relative importance of volumetric strain and chemical mass loss in the Southern Sierra Critical Zone Observatory. Our results from cores of saprolite show that porosity decreases with depth from 0.65 to 0.35 in the top 11 meters of saprolite. Although seismic refraction surveys reveal velocities that correctly predict the porosity variations, they cannot distinguish between volumetric strain and chemical mass losses. To overcome this limitation, we quantified bulk density and immobile element concentrations in our samples of saprolite. We found that volumetric strain decreases with depth from 1.1 to 0.3. Conversely, the overall mass loss due to chemical weathering shows no trend with depth. Together these results suggest that the changes in porosity are due to physical rather than chemical processes in the upper 11 meters. However neither bioturbation nor frost cracking are likely to extend so deep. Moreover, the paucity of hydrous minerals in the bedrock implies that mineral expansion cannot explain the high volumetric strain in the saprolite. Our results are consistent with porosity generated by the opening of fractures due to the release of confining stress during exhumation of bedrock.

  9. OnabotulinumtoxinA (Botox) nerve blocks provide durable pain relief for men with chronic scrotal pain: a pilot open-label trial.

    Science.gov (United States)

    Khambati, Aziz; Lau, Susan; Gordon, Allan; Jarvi, Keith A

    2014-12-01

    Chronic scrotal pain (CSP) is a common, often debilitating, condition affecting approximately 4.75% of men. While nerve blocks using local anesthetics usually provide temporary pain relief, there are no publications on the use of longer acting nerve blocks to provide more durable pain relief for men with CSP. The aim of this study was to determine if onabotulinumtoxinA (Botox) cord blocks provide durable pain relief for men with CSP. In this pilot open-label study, men with CSP who had failed medical management but experienced temporary pain relief from a standard cord block underwent a cord block with 100U Botox. The outcomes measured were changes 1, 3, and 6 months post-Botox injection in (i) a 10-point visual analog scale (VAS) pain score; (ii) scrotal tenderness on a three-point scale as rated by physical examination; and (iii) the Chronic Epididymitis Symptom Index (CESI) to measure the severity and impact of scrotal pain on men. Paired t-tests were used to compare groups. Eighteen patients with CSP seen between April and September 2013 had Botox injected as a cord block. At the 1-month follow-up, pain reduction was reported by 72% of patients (mean VAS score: 7.36 vs. 5.61, P Botox cord blocks provide pain reduction for 3 months or more for most men with CSP. © 2014 International Society for Sexual Medicine.

  10. Experiences with HPTN 067/ADAPT Study-Provided Open-Label PrEP Among Women in Cape Town: Facilitators and Barriers Within a Mutuality Framework.

    Science.gov (United States)

    Amico, K Rivet; Wallace, Melissa; Bekker, Linda-Gail; Roux, Surita; Atujuna, Millicent; Sebastian, Elaine; Dye, Bonnie J; Elharrar, Vanessa; Grant, Robert M

    2017-05-01

    Placebo-controlled trials of pre-exposure prophylaxis (PrEP) have reported challenges with study-product uptake and use, with the greatest challenges reported in studies with young women in sub-Saharan Africa. We conducted a qualitative sub-study to explore experiences with open-label PrEP among young women in Cape Town, South Africa participating in HTPN 067/Alternative Dosing to Augment Pre-Exposure Prophylaxis Pill Taking (ADAPT). HPTN 067/ADAPT provided open label oral FTC/TDF PrEP to young women in Cape Town, South Africa who were randomized to daily and non-daily PrEP regimens. Following completion of study participation, women were invited into a qualitative sub-study including focus groups and in-depth interviews. Interviews and groups followed a semi-structured guide, were recorded, transcribed, and translated to English from isiXhosa, and coded using framework analysis. Sixty of the 179 women enrolled in HPTN 067/ADAPT participated in either a focus group (six groups for a total of 42 participants) or an in-depth interview (n = 18). This sample of mostly young, unmarried women identified facilitators of and barriers to PrEP use, as well as factors influencing study participation. Cross-cutting themes characterizing discourse suggested that women placed high value on contributing to the well-being of one's community (Ubuntu), experienced a degree of skepticism towards PrEP and the study more generally, and reported a wide range of approaches towards PrEP (ranging from active avoidance to high levels of persistence and adherence). A Mutuality Framework is proposed that identifies four dynamics (distrust, uncertainty, alignment, and mutuality) that represent distinct interactions between self, community and study and serve to contextualize women's experiences. Implications for better understanding PrEP use, and non-use, and intervention opportunities are discussed. In this sample of women, PrEP use in the context of an open-label research trial was heavily

  11. Porosity estimation by semi-supervised learning with sparsely available labeled samples

    Science.gov (United States)

    Lima, Luiz Alberto; Görnitz, Nico; Varella, Luiz Eduardo; Vellasco, Marley; Müller, Klaus-Robert; Nakajima, Shinichi

    2017-09-01

    This paper addresses the porosity estimation problem from seismic impedance volumes and porosity samples located in a small group of exploratory wells. Regression methods, trained on the impedance as inputs and the porosity as output labels, generally suffer from extremely expensive (and hence sparsely available) porosity samples. To optimally make use of the valuable porosity data, a semi-supervised machine learning method was proposed, Transductive Conditional Random Field Regression (TCRFR), showing good performance (Görnitz et al., 2017). TCRFR, however, still requires more labeled data than those usually available, which creates a gap when applying the method to the porosity estimation problem in realistic situations. In this paper, we aim to fill this gap by introducing two graph-based preprocessing techniques, which adapt the original TCRFR for extremely weakly supervised scenarios. Our new method outperforms the previous automatic estimation methods on synthetic data and provides a comparable result to the manual labored, time-consuming geostatistics approach on real data, proving its potential as a practical industrial tool.

  12. Self-Assembling Sup-porosity: The Effect On Fluid Flow And Seismic Wave Propagation

    Energy Technology Data Exchange (ETDEWEB)

    Pyrak-Nolte, Laura J. [Purdue University

    2013-04-27

    Fractures and joints in the field often contain debris within the void spaces. Debris originates from many different mechanisms: organic and/or inorganic chemical reactions/mineralization, sediment transport, formation of a fracture, mechanical weathering or combinations of these processes. In many cases, the presence of debris forms a sub-porosity within the fracture void space. This sub-porosity often is composed of material that differs from the fracture walls in mineralogy and morphology. The sub-porosity may partially fill voids that are on the order of hundreds of microns and thereby reduce the local porosity to lengths scales on the order of sub-microns to tens of microns. It is quite clear that a sub-porosity affects fracture porosity, permeability and storativity. What is not known is how the existence/formation of a sub-porosity affects seismic wave propagation and consequently our ability to probe changes in the subsurface caused by the formation or alteration of a sub-porosity. If seismic techniques are to be developed to monitor the injection and containment of phases in sequestration reservoirs or the propping of hydraulically induced fracture to enhance oil & gas production, it is important to understand how a sub-porosity within a fracture affects macroscopic seismic and hydraulic measurements. A sub-porosity will directly affect the interrelationship between the seismic and hydraulic properties of a fracture. This reports contains the results of the three main topics of research that were performed (1) to determine the effect of a sub-porosity composed of spherical grains on seismic wave propagation across fractures, (2) to determine the effect of biofilm growth in pores and between grains on seismic wave propagation in sediment, and (3) to determine the effect of the scale of observation (field-of-view) on monitoring alteration the pore space within a fracture caused by reactive flow. A brief summary of the results for each topic is contained in

  13. 3D Membrane Imaging and Porosity Visualization

    KAUST Repository

    Sundaramoorthi, Ganesh

    2016-03-03

    Ultrafiltration asymmetric porous membranes were imaged by two microscopy methods, which allow 3D reconstruction: Focused Ion Beam and Serial Block Face Scanning Electron Microscopy. A new algorithm was proposed to evaluate porosity and average pore size in different layers orthogonal and parallel to the membrane surface. The 3D-reconstruction enabled additionally the visualization of pore interconnectivity in different parts of the membrane. The method was demonstrated for a block copolymer porous membrane and can be extended to other membranes with application in ultrafiltration, supports for forward osmosis, etc, offering a complete view of the transport paths in the membrane.

  14. Porosity and liquid absorption of cement paste

    DEFF Research Database (Denmark)

    Krus, M.; Hansen, Kurt Kielsgaard; Kunzel, H. M.

    1997-01-01

    be a slowing-down effect which is related to water because the absorption of organic liquids, such as hexane, is quite normal. Measurements of the porosity of hardened cement paste determined by helium pycnometry and water saturation show that water molecules can enter spaces in the microstructure which...... are not accessible to the smaller helium atoms. Considering the results of dilatation tests both before and after water and hexane saturation, it seems possible that a contraction of capillary pores due to moisture-related swelling of the cement gel leads to the non-linear water absorption over the square root...

  15. Results from a new Cocks-Ashby style porosity model

    Science.gov (United States)

    Barton, Nathan

    2017-01-01

    A new porosity evolution model is described, along with preliminary results. The formulation makes use of a Cocks-Ashby style treatment of porosity kinetics that includes rate dependent flow in the mechanics of porosity growth. The porosity model is implemented in a framework that allows for a variety of strength models to be used for the matrix material, including ones with significant changes in rate sensitivity as a function of strain rate. Results of the effect of changing strain rate sensitivity on porosity evolution are shown. The overall constitutive model update involves the coupled solution of a system of nonlinear equations.

  16. Porosity of additive manufacturing parts for process monitoring

    Science.gov (United States)

    Slotwinski, J. A.; Garboczi, E. J.

    2014-02-01

    Some metal additive manufacturing processes can produce parts with internal porosity, either intentionally (with careful selection of the process parameters) or unintentionally (if the process is not well-controlled.) Material porosity is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants, since surface-breaking pores allow for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the process. We are developing an ultrasonic sensor for detecting changes in porosity in metal parts during fabrication on a metal powder bed fusion system, for use as a process monitor. This paper will describe our work to develop an ultrasonic-based sensor for monitoring part porosity during an additive build, including background theory, the development and detailed characterization of reference additive porosity samples, and a potential design for in-situ implementation.

  17. Fabrication of slag-glass composite with controlled porosity

    Directory of Open Access Journals (Sweden)

    Ranko Adziski

    2008-06-01

    Full Text Available The preparation and performance of porous ceramics made from waste materials were investigated. Slag from thermal electrical plant Kakanj (Bosnia and Herzegovina with defined granulations: (0.500÷0.250 mm; (0.250÷0.125 mm; (0.125÷0.063 mm; (0.063÷0.045 mm and 20/10 wt.% of the waste TV screen glass with a granulation <0.063 mm were used for obtaining slag-glass composites with controlled porosity. The one produced from the slag powder fraction (0.125÷0.063 mm and 20 wt.% TV screen glass, sintered at 950°C/2h, was considered as the optimal. This system possesses open porosity of 26.8±1.0%, and interconnected pores with the size of 250–400 μm. The values of E-modulus and bending strength of this composite were 10.6±0.6 GPa and 45.7±0.7 MPa, respectively. The coefficient of thermal expansion was 8.47·10-6/°C. The mass loss in 0.1M HCl solution after 30 days was 1.2 wt.%. The permeability and the form coefficient of the porous composite were K0=0.12 Da and C0=4.53·105 m-1, respectively. The porous composite shows great potential to be used as filters, diffusers for water aeration, dust collectors, acoustic absorbers, etc.

  18. Effect of porosity, tissue density, and mechanical properties on radial sound speed in human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Eneh, C. T. M., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi; Töyräs, J., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi; Jurvelin, J. S., E-mail: jukka.jurvelin@uef.fi [Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland and Diagnostic Imaging Center, Kuopio University Hospital, P.O. Box 100, Kuopio FI-70029 (Finland); Malo, M. K. H., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi; Liukkonen, J., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi [Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211 (Finland); Karjalainen, J. P., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi [Bone Index Finland Ltd., P.O. Box 1188, Kuopio FI-70211 (Finland)

    2016-05-15

    Purpose: The purpose of this study was to investigate the effect of simultaneous changes in cortical porosity, tissue mineral density, and elastic properties on radial speed of sound (SOS) in cortical bone. The authors applied quantitative pulse-echo (PE) ultrasound techniques that hold much potential especially for screening of osteoporosis at primary healthcare facilities. Currently, most PE measurements of cortical thickness, a well-known indicator of fracture risk, use a predefined estimate for SOS in bone to calculate thickness. Due to variation of cortical bone porosity, the use of a constant SOS value propagates to an unknown error in cortical thickness assessment by PE ultrasound. Methods: The authors conducted 2.25 and 5.00 MHz focused PE ultrasound time of flight measurements on femoral diaphyses of 18 cadavers in vitro. Cortical porosities of the samples were determined using microcomputed tomography and related to SOS in the samples. Additionally, the effect of cortical bone porosity and mechanical properties of the calcified matrix on SOS was investigated using numerical finite difference time domain simulations. Results: Both experimental measurements and simulations demonstrated significant negative correlation between radial SOS and cortical porosity (R{sup 2} ≥ 0.493, p < 0.01 and R{sup 2} ≥ 0.989, p < 0.01, respectively). When a constant SOS was assumed for cortical bone, the error due to variation of cortical bone porosity (4.9%–16.4%) was about 6% in the cortical thickness assessment in vitro. Conclusions: Use of a predefined, constant value for radial SOS in cortical bone, i.e., neglecting the effect of measured variation in cortical porosity, propagated to an error of 6% in cortical thickness. This error can be critical as characteristic cortical thinning of 1.10% ± 1.06% per yr decreases bending strength of the distal radius and results in increased fragility in postmenopausal women. Provided that the cortical porosity can be estimated

  19. Evaluation of concrete mechanical strength through porosity

    Directory of Open Access Journals (Sweden)

    Olivares, M.

    2004-03-01

    Full Text Available The increasing on voids or pores in any material - if the rest of characteristics remains equal -always causes a decrease in their mechanical strength since the ratio volume/resistant mass is lower Following all these fact a well known conclusion rises: there is a relationship between compacity/porosity and mechanical strengths. The purpose of this research is to establish a new possible correlation between both concrete properties with independence of the proportions, type of cement, size of grain, age, use. etc. So it can be concluded that the results of this research allow the engineer or architect in charge of a restoration or reparation to determine the compression strength of a concrete element. A first step is to determine the porosity through a rather short number of tests. Subsequently, compression strength will be obtained applying just a mathematical formula.

    El aumento de huecos o poros de cualquier material, lo mismo que en otras circunstancias, redunda siempre en una merma de sus resistencias mecánicas, al haber menor volumen-masa resistente. En consecuencia, puede deducirse, que hay una relación entre la compacidad/porosidad y las resistencias mecánicas. En el presente trabajo se estudia una posible correlación entre ambas propiedades del hormigón con independencia de su dosificación, tipo de cemento, granulometría, edad, uso, etc. Las conclusiones obtenidas en la presente investigación permiten al técnico, encargado de una restauración o rehabilitación, determinar la resistencia a compresión de un elemento de hormigón, una vez hallada, de una forma sencilla, la porosidad de una muestra no muy voluminosa, mediante la aplicación de una simple fórmula matemática.

  20. Plastic Foam Porosity Characterization by Air-Borne Ultrasound

    Science.gov (United States)

    Hoffrén, H.; Karppinen, T.; Hæggström, E.

    2006-03-01

    We continue to develop an ultrasonic burst-reflection method for estimating porosity and tortuosity of solid materials. As a first step we report on method design considerations and measurements on polyurethane foams (Sylomer® vibration dampener) with well-defined porosity. The ultrasonic method is experimentally tested by measuring 235 kHz and 600 kHz air-borne ultrasound reflection from a foam surface at two incidence angles. The reflected sound wave from different foam samples (32% - 64% porosity) was compared to a wave that had traveled from the transmitter to the detector without reflection. The ultrasonically estimated sample porosities coincided within 8% with the porosity estimates obtained by a gravimetric reference method. This parallels the uncertainty of the gravimetric method, 8%. The repeatability of the ultrasonic porosity measurements was better than 5%.

  1. Towards assessing cortical bone porosity using low-frequency quantitative acoustics: A phantom-based study.

    Directory of Open Access Journals (Sweden)

    Florian Vogl

    shown the capability of low-frequency quantitative acoustics to reflect changes in porosity and individual pore characteristics and demonstrated that additive manufacturing is an appropriate method that allows the influence of individual bone properties on the wave propagation to be systematically assessed. The results of this work opens perspectives for the efficient development of a multi-frequency, multi-mode approach to screen, diagnose, and monitor bone pathologies in individuals.

  2. Towards assessing cortical bone porosity using low-frequency quantitative acoustics: A phantom-based study.

    Science.gov (United States)

    Vogl, Florian; Bernet, Benjamin; Bolognesi, Daniele; Taylor, William R

    2017-01-01

    capability of low-frequency quantitative acoustics to reflect changes in porosity and individual pore characteristics and demonstrated that additive manufacturing is an appropriate method that allows the influence of individual bone properties on the wave propagation to be systematically assessed. The results of this work opens perspectives for the efficient development of a multi-frequency, multi-mode approach to screen, diagnose, and monitor bone pathologies in individuals.

  3. Acti-Tape™ (elastic therapeutic tape as compared with a knee guard in providing support to the knee joint: an open-label, randomized, crossover study

    Directory of Open Access Journals (Sweden)

    Hui HK

    2014-04-01

    Full Text Available Hoong Keong Hui,1 Narayan J Karne,2 Navneet Sonawane31Nutriworks Ltd, Kowloon, Hong Kong; 2Karne Hospital, Pune, India; 3Vedic Lifesciences Pvt Ltd, Mumbai, IndiaStudy design: Randomized, open-label, crossover, controlled study.Background: Elastic taping methods are used to provide support to the musculoskeletal system in athletes. Acti-Tape™ (an elastic therapeutic tape has been marketed for the last 2–3 years and has shown good results in providing support to the joints. This pilot study was planned to collect data on the clinical outcomes and to assess if a single tape application of Acti-Tape over the knee joint could provide benefits similar to a traditionally used knee guard.Methods: Thirteen subjects aged 30–65 years visiting an orthopedic center in Pune, India who were suffering from osteoarthritis were randomly assigned to either Acti-Tape (n=6 or a knee guard (n=7 in the first intervention period (6 days and were crossed over to the other group in the second intervention period (6 days after a washout of 1 day. Main outcome measures were change from day 0 to day 6 in pain visual analog score (VAS; timed up and go (TUG, medial step down (MSD, and unilateral anterior reach (UAR tests; and subject's preference.Results: Data for all the 13 subjects were pooled and analyzed by Student's t-test as treatment-by-period interaction was not significant by analysis of variance (P>0.05. The changes (mean ± standard deviation after using Acti-Tape and a knee guard, respectively, were pain VAS, –10±5.4 versus (vs –11.5±5.83; TUG, –0.62±1.33 vs –0.46±1.56; UAR, 0.15±1.07 vs 0.75±0.44; and MSD, 1.08±095 vs 0.85±1.14. These were statistically significant with both devices for pain VAS, UAR, and MSD, but not for TUG. Between the treatments however, no statistically significant difference was seen. Eleven of 13 (85% subjects preferred Acti-Tape for future use (P<0.05 by McNemar’s χ2 test. No safety concerns were reported by the

  4. Effectiveness of artemether-lumefantrine provided by community health workers in under-five children with uncomplicated malaria in rural Tanzania: an open label prospective study

    Directory of Open Access Journals (Sweden)

    Blessborn Daniel

    2011-03-01

    Full Text Available Abstract Background Home-management of malaria (HMM strategy improves early access of anti-malarial medicines to high-risk groups in remote areas of sub-Saharan Africa. However, limited data are available on the effectiveness of using artemisinin-based combination therapy (ACT within the HMM strategy. The aim of this study was to assess the effectiveness of artemether-lumefantrine (AL, presently the most favoured ACT in Africa, in under-five children with uncomplicated Plasmodium falciparum malaria in Tanzania, when provided by community health workers (CHWs and administered unsupervised by parents or guardians at home. Methods An open label, single arm prospective study was conducted in two rural villages with high malaria transmission in Kibaha District, Tanzania. Children presenting to CHWs with uncomplicated fever and a positive rapid malaria diagnostic test (RDT were provisionally enrolled and provided AL for unsupervised treatment at home. Patients with microscopy confirmed P. falciparum parasitaemia were definitely enrolled and reviewed weekly by the CHWs during 42 days. Primary outcome measure was PCR corrected parasitological cure rate by day 42, as estimated by Kaplan-Meier survival analysis. This trial is registered with ClinicalTrials.gov, number NCT00454961. Results A total of 244 febrile children were enrolled between March-August 2007. Two patients were lost to follow up on day 14, and one patient withdrew consent on day 21. Some 141/241 (58.5% patients had recurrent infection during follow-up, of whom 14 had recrudescence. The PCR corrected cure rate by day 42 was 93.0% (95% CI 88.3%-95.9%. The median lumefantrine concentration was statistically significantly lower in patients with recrudescence (97 ng/mL [IQR 0-234]; n = 10 compared with reinfections (205 ng/mL [114-390]; n = 92, or no parasite reappearance (217 [121-374] ng/mL; n = 70; p ≤ 0.046. Conclusions Provision of AL by CHWs for unsupervised malaria treatment at home

  5. Demineralized dentin 3D porosity and pore size distribution using mercury porosimetry.

    Science.gov (United States)

    Vennat, Elsa; Bogicevic, Christine; Fleureau, Jean-Marie; Degrange, Michel

    2009-06-01

    The objectives of this study were to assess demineralized dentin porosity and quantify the different porous features distribution within the material using mercury intrusion porosimetry (MIP) technique. We compared hexamethyldisilazane (HMDS) drying and lyophilization (LYO) (freeze-drying) in sample preparation. Fifty-six dentin discs were assigned into three groups. The control (CTR) group discs were superficially acid-etched (15s 37% H(3)PO(4)) to remove the smear layer and then freeze-dried whereas LYO and HMDS groups samples were first totally demineralized using EDTA 0.5M and then freeze-dried and HMDS-dried respectively. MIP was used to determine open porosity and pore size distribution of each pair of samples. Field emission scanning electron microscopy (FESEM) was used to illustrate the results. The results showed two types of pores corresponding either to tubules and micro-branches or to inter-fibrillar spaces created by demineralization. Global porosity varied from 59% (HMDS-dried samples) to 70% (freeze-dried samples). Lyophilization drying technique seems to lead to less shrinkage than HMDS drying. FESEM revealed that collagen fibers of demineralized lyophilized samples are less melted together than in the HMDS-dried samples. Demineralized dentin porosity is a key parameter in dentin bonding that will influence the hybrid layer quality. Its characterization could be helpful to improve the monomers infiltration.

  6. Pore-level determination of spectral reflection behaviors of high-porosity metal foam sheets

    Science.gov (United States)

    Li, Yang; Xia, Xin-Lin; Ai, Qing; Sun, Chuang; Tan, He-Ping

    2018-03-01

    Open cell metal foams are currently attracting attention and their radiative behaviors are of primary importance in high temperature applications. The spectral reflection behaviors of high-porosity metal foam sheets, bidirectional reflectance distribution function (BRDF) and directional-hemispherical reflectivity were numerically investigated. A set of realistic nickel foams with porosity from 0.87 to 0.97 and pore density from 10 to 40 pores per inch were tomographied to obtain their 3-D digital cell network. A Monte Carlo ray-tracing method was employed in order to compute the pore-level radiative transfer inside the network within the limit of geometrical optics. The apparent reflection behaviors and their dependency on the textural parameters and strut optical properties were comprehensively computed and analysed. The results show a backward scattering of the reflected energy at the foam sheet surface. Except in the cases of large incident angles, an energy peak is located almost along the incident direction and increases with increasing incident angles. Through an analytical relation established, the directional-hemispherical reflectivity can be related directly to the porosity of the foam sheet and to the complex refractive index of the solid phase as well as the specularity parameter which characterizes the local reflection model. The computations show that a linear decrease in normal-hemispherical reflectivity occurs with increasing porosity. The rate of this decrease is directly proportional to the strut normal reflectivity. In addition, the hemispherical reflectivity increases as a power function of the incident angle cosine.

  7. Porosity and Salt Content Determine if Subduction Can Occur in Europa's Ice Shell

    Science.gov (United States)

    Johnson, Brandon C.; Sheppard, Rachel Y.; Pascuzzo, Alyssa C.; Fisher, Elizabeth A.; Wiggins, Sean E.

    2017-12-01

    Motivated by recent evidence for subduction in Europa's ice shell, we explore the geophysical feasibility of this process. Here we construct a simple model to track the evolution of porosity and temperature within a slab that is forced to subduct. We also vary the initial salt content in Europa's ice shell and determine the buoyancy of our simulated subducting slab. We find that porosity and salt content play a dominant role in determining whether the slab is nonbuoyant and subduction in Europa's ice shell is actually possible. Generally, we find that initially low porosities and high salt contents within the conductive lid are more conducive to subduction. If salt contents are laterally homogenous, and Europa has a reasonable surface porosity of ϕ0 = 0.1, the conductive portion of Europa's shell must have salt contents exceeding 22% for subduction to occur. However, if salt contents are laterally heterogeneous, with salt contents varying by a few percent, subduction may occur for a surface porosity of ϕ0 = 0.1 and overall salt contents of 5%. Thus, we argue that under plausible conditions, subduction in Europa's ice shell is possible. Moreover, assuming that subduction is actively occurring or has occurred in Europa's recent past provides important constraints on the structure and composition of the ice shell.

  8. Porosity and Health: Perspective of Traditional Persian Medicine.

    Science.gov (United States)

    Tafazoli, Vahid; Nimrouzi, Majid; Daneshfard, Babak

    2016-05-01

    The authors of this manuscript aimed to show the importance of porosity and condensation in health according to traditional Persian medicine (TPM) with consideration of new evidence in conventional medicine. Cardinal traditional medical and pharmacological texts were searched for the traditional terms of takhalkhol (porosity) and takassof (condensity) focused on preventive methods. The findings were classified and compared with new medical findings. According to traditional Persian medicine, porosity and condensity are the two crucial items that contribute to human health. Somatotype is a taxonomy based on embryonic development, which may be considered in parallel with porosity and condensation. However, these terms are not completely the same. There are many causes for acquired porosity comprising hot weather, too much intercourse, rage, starvation, and heavy exercises. In general, porosity increases the risk of diseases as it makes the body organs vulnerable to external hot and cold weather. On the other hand, the porose organs are more susceptible to accumulation of morbid matters because the cellular wastes cannot be evacuated in the normal way. There are some common points between traditional and conventional medicine in the context of porosity and condensity. The relation between diet and somatotype is an example. Condensity and porosity are the two basic items cited in the TPM resources and contribute to health maintenance and disease prevention of body organs. Creating a balance between these two states in different body organs, strongly contributes to disease prevention, treatment and diminishing chronic diseases period. Choosing proper modality including diet, drug therapy, and manual therapy depends on the amount porosity and stiffness of the considered organ and the preferred porosity of the affected organ keeping in a normal healthy state.

  9. Reconciling the discrepancies between crystallographic porosity and guest access as exemplified by Zn-HKUST-1.

    Science.gov (United States)

    Feldblyum, Jeremy I; Liu, Ming; Gidley, David W; Matzger, Adam J

    2011-11-16

    There are several compounds for which there exists a disconnect between porosity as predicted by crystallography and porosity measured by gas sorption analysis. In this paper, the Zn-based analogue of Cu(3)(btc)(2) (HKUST-1), Zn(3)(btc)(2) (Zn-HKUST-1; btc = 1,3,5-benzenetricarboxylate) is investigated. Conventional analysis of Zn-HKUST-1 by powder X-ray diffraction and gas sorption indicates retention of crystalline structure but negligible nitrogen uptake at 77 K. By using positron annihilation lifetime spectroscopy, a densified surface layer preventing the entry of even small molecular species into the crystal framework is revealed. The material is shown to have inherent surface instability after solvent removal, rendering it impermeable to molecular guests irrespective of handling and processing methods. This previously unobserved surface instability may provide insight into the failure of other microporous coordination polymers to exhibit significant porosity despite crystal structures indicative of regular, interconnected, microporous networks.

  10. An Adaptable Analytical Ergun-Type Equation For High Porosity Spongelike Porous Media

    Science.gov (United States)

    Woudberg, Sonia; Prieur du Plessis, J.

    2010-05-01

    An analytical Ergun-type equation for spongelike media is introduced in which developing flow in the short ducts of high porosity metallic foams are accounted for. Instead of the customary procedure of adjusting the empirical coefficients of the Ergun equation to apply to consolidated spongelike media, a pore scale model is introduced and the physical flow conditions remodelled. The pore-scale linear dimensions are expressed as a function of porosity and the dependence of the form drag coefficient on porosity is incorporated into the model which leads to satisfactory predictions for the inertial coefficient. The model predictions are compared to experimental data from the literature and the satisfactory correspondence provides confidence in the physical adaptability of the model.

  11. Laser Carbonization of PAN-Nanofiber Mats with Enhanced Surface Area and Porosity.

    Science.gov (United States)

    Go, Dennis; Lott, Philipp; Stollenwerk, Jochen; Thomas, Helga; Möller, Martin; Kuehne, Alexander J C

    2016-10-26

    Here we present a novel laser process to generate carbon nanofiber nonwovens from polyacrylonitrile. We produce carbon nanofabrics via electrospinning followed by infrared laser-induced carbonization, facilitating high surface area and well-controlled hierarchical porosity. The process allows precise control of the carbonization conditions and provides high nanoscale porosity. In comparison with classical thermal carbonization, the laser process produces much higher surface areas and smaller pores. Furthermore, we investigate the carbonization performance and the morphology of polyacrylonitrile nanofibers compounded with graphene nanoplatelet fillers.

  12. Waste-to-resource preparation of a porous ceramic membrane support featuring elongated mullite whiskers with enhanced porosity and permeance

    NARCIS (Netherlands)

    Zhu, Li; Dong, Yingchao; Hampshire, Stuart; Cerneaux, Sophie; Winnubst, Aloysius J.A.

    2015-01-01

    Different from traditional particle packing structure, a porous structure of ceramic membrane support was fabricated, featuring elongated mullitewhiskers with enhanced porosity, permeance and sufficient mechanical strength. The effect of additives (MoO3and AlF3) and sintering procedureon open

  13. Porosity effects during a severe accident

    Energy Technology Data Exchange (ETDEWEB)

    Cazares R, R. I. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Posgrado en Energia y Medio Ambiente, San Rafael Atlixco 186, Col. Vicentina, 09340 Ciudad de Mexico (Mexico); Espinosa P, G.; Vazquez R, A., E-mail: ricardo-cazares@hotmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, San Rafael Atlixco 186, Col. Vicentina, 09340 Ciudad de Mexico (Mexico)

    2015-09-15

    The aim of this work is to study the behaviour of porosity effects on the temporal evolution of the distributions of hydrogen concentration and temperature profiles in a fuel assembly where a stream of steam is flowing. The analysis considers the fuel element without mitigation effects. The mass transfer phenomenon considers that the hydrogen generated diffuses in the steam by convection and diffusion. Oxidation of the cladding, rods and other components in the core constructed in zirconium base alloy by steam is a critical issue in LWR accident producing severe core damage. The oxygen consumed by the zirconium is supplied by the up flow of steam from the water pool below the uncovered core, supplemented in the case of PWR by gas recirculation from the cooler outer regions of the core to hotter zones. Fuel rod cladding oxidation is then one of the key phenomena influencing the core behavior under high-temperature accident conditions. The chemical reaction of oxidation is highly exothermic, which determines the hydrogen rate generation and the cladding brittleness and degradation. The heat transfer process in the fuel assembly is considered with a reduced order model. The Boussinesq approximation was applied in the momentum equations for multicomponent flow analysis that considers natural convection due to buoyancy forces, which is related with thermal and hydrogen concentration effects. The numerical simulation was carried out in an averaging channel that represents a core reactor with the fuel rod with its gap and cladding and cooling steam of a BWR. (Author)

  14. Casting Porosity-Free Grain Refined Magnesium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Schwam, David [Case Western Reserve University

    2013-08-12

    The objective of this project was to identify the root causes for micro-porosity in magnesium alloy castings and recommend remedies that can be implemented in production. The findings confirm the key role played by utilizing optimal gating and risering practices in minimizing porosity in magnesium castings. 

  15. Tailoring the porosity of hierarchical zeolites by carbon-templating

    DEFF Research Database (Denmark)

    Zhu, Kake; Egeblad, Kresten; Christensen, Claus H.

    2008-01-01

    We report the synthesis and characterization of a series of hierarchical porous zeolite single crystal materials with a range of porosities made available by carbon-templating using differently-sized carbon particles as templates for the additional non-micropore porosity. The materials were...

  16. Porosity prediction from seismic inversion, Lavrans Field, Halten Terrace

    Energy Technology Data Exchange (ETDEWEB)

    Dolberg, David M.

    1998-12-31

    This presentation relates to porosity prediction from seismic inversion. The porosity prediction concerns the Lavrans Field of the Halten Terrace on the Norwegian continental shelf. The main themes discussed here cover seismic inversion, rock physics, statistical analysis - verification of well trends, upscaling/sculpting, and implementation. 2 refs., 6 figs.

  17. Porosity variabilities along a forest – grassland mosaic in Ibeku ...

    African Journals Online (AJOL)

    Variation existed in the porosity characteristics of pedons located on forestland and grassland. Percent coefficient of variation (CV) was greater in forest soils for both bulk density and porosity (% CV = 29.99 and 13.2) than as found in grassland soils (% CV = 2.6 and. 4.1). These results were explained by wide variations in ...

  18. Application of small-angle neutron scattering (SANS) to the study of coal porosity

    Energy Technology Data Exchange (ETDEWEB)

    Tricker, M.J.; Grint, A.; Audley, G.J.; Church, S.M. (British Petroleum Co. Ltd., Sunbury-on-Thames); Rainey, V.S.; Wright, C.J. (UKAEA Atomic Energy Research Establishment, Harwell)

    1983-09-01

    Pore size distribution functions of coals of different rank obtained from small-angle neutron scattering data are quantitatively consistent with data obtained from adsorption measurements. The agreement will provide a firm foundation for using SANS to probe coal porosity under conditions where conventional gas adsorption techniques are inappropriate.

  19. Application of small-angle neutron scattering (SANS) to the study of coal porosity

    Energy Technology Data Exchange (ETDEWEB)

    Tricker, M.J.; Grint, A.; Audley, G.J.; Church, S.M.; Rainey, V.S.; Wright, C.J.

    1983-09-01

    Pore size distribution functions of coals of different rank obtained from small-angle neutron scattering data are quantitatively consistent with data obtained from adsorption measurements. The agreement will provide a firm foundation for using SANS to probe coal porosity under conditions where conventional gas adsorption techniques are inappropriate. (14 refs.)

  20. Constraints on Porosity and Mass Loss in O-star Winds from the Modeling of X-ray Emission Line Profile Shapes

    Science.gov (United States)

    Leutenegger, Maurice A.; Cohen, David H.; Sundqvist, Jon O.; Owocki, Stanley P.

    2013-01-01

    We fit X-ray emission line profiles in high resolution XMM-Newton and Chandra grating spectra of the early O supergiant Zeta Pup with models that include the effects of porosity in the stellar wind. We explore the effects of porosity due to both spherical and flattened clumps. We find that porosity models with flattened clumps oriented parallel to the photosphere provide poor fits to observed line shapes. However, porosity models with isotropic clumps can provide acceptable fits to observed line shapes, but only if the porosity effect is moderate. We quantify the degeneracy between porosity effects from isotropic clumps and the mass-loss rate inferred from the X-ray line shapes, and we show that only modest increases in the mass-loss rate (40%) are allowed if moderate porosity effects (h(sub infinity) less than approximately R(sub *)) are assumed to be important. Large porosity lengths, and thus strong porosity effects, are ruled out regardless of assumptions about clump shape. Thus, X-ray mass-loss rate estimates are relatively insensitive to both optically thin and optically thick clumping. This supports the use of X-ray spectroscopy as a mass-loss rate calibration for bright, nearby O stars

  1. Formation of a p-n heterojunction on GaP photocathodes for H-2 production providing an open-circuit voltage of 710 mV

    DEFF Research Database (Denmark)

    Malizia, Mauro; Seger, Brian; Chorkendorff, Ib

    2014-01-01

    Photocatalytic water splitting for the sustainable production of hydrogen using a two-photon tandem device requires careful optimization of the semiconductors used as photon absorbers. In this work we show how the open-circuit voltage of photocathodes for the hydrogen evolution reaction based on ...

  2. 3D Porosity Estimation of the Nankai Trough Sediments from Core-log-seismic Integration

    Science.gov (United States)

    Park, J. O.

    2015-12-01

    The Nankai Trough off southwest Japan is one of the best subduction-zone to study megathrust earthquake fault. Historic, great megathrust earthquakes with a recurrence interval of 100-200 yr have generated strong motion and large tsunamis along the Nankai Trough subduction zone. At the Nankai Trough margin, the Philippine Sea Plate (PSP) is being subducted beneath the Eurasian Plate to the northwest at a convergence rate ~4 cm/yr. The Shikoku Basin, the northern part of the PSP, is estimated to have opened between 25 and 15 Ma by backarc spreading of the Izu-Bonin arc. The >100-km-wide Nankai accretionary wedge, which has developed landward of the trench since the Miocene, mainly consists of offscraped and underplated materials from the trough-fill turbidites and the Shikoku Basin hemipelagic sediments. Particularly, physical properties of the incoming hemipelagic sediments may be critical for seismogenic behavior of the megathrust fault. We have carried out core-log-seismic integration (CLSI) to estimate 3D acoustic impedance and porosity for the incoming sediments in the Nankai Trough. For the CLSI, we used 3D seismic reflection data, P-wave velocity and density data obtained during IODP (Integrated Ocean Drilling Program) Expeditions 322 and 333. We computed acoustic impedance depth profiles for the IODP drilling sites from P-wave velocity and density data. We constructed seismic convolution models with the acoustic impedance profiles and a source wavelet which is extracted from the seismic data, adjusting the seismic models to observed seismic traces with inversion method. As a result, we obtained 3D acoustic impedance volume and then converted it to 3D porosity volume. In general, the 3D porosities show decrease with depth. We found a porosity anomaly zone with alteration of high and low porosities seaward of the trough axis. In this talk, we will show detailed 3D porosity of the incoming sediments, and present implications of the porosity anomaly zone for the

  3. Establishment of metrological traceability in porosity measurements by x-ray computed tomography

    Science.gov (United States)

    Hermanek, Petr; Carmignato, Simone

    2017-09-01

    Internal porosity is an inherent phenomenon to many manufacturing processes, such as casting, additive manufacturing, and others. Since these defects cannot be completely avoided by improving production processes, it is important to have a reliable method to detect and evaluate them accurately. The accurate evaluation becomes even more important concerning current industrial trends to minimize size and weight of products on one side, and enhance their complexity and performance on the other. X-ray computed tomography (CT) has emerged as a promising instrument for holistic porosity measurements offering several advantages over equivalent methods already established in the detection of internal defects. The main shortcomings of the conventional techniques pertain to too general information about total porosity content (e.g. Archimedes method) or the destructive way of testing (e.g. microscopy of cross-sections). On the contrary, CT is a nondestructive technique providing complete information about size, shape and distribution of internal porosity. However, due to the lack of international standards and the fact that it is relatively a new measurement technique, CT as a measurement technology has not yet reached maturity. This study proposes a procedure for the establishment of measurement traceability in porosity measurements by CT including the necessary evaluation of measurement uncertainty. The traceability transfer is carried out through a novel reference standard calibrated by optical and tactile coordinate measuring systems. The measurement uncertainty is calculated following international standards and guidelines. In addition, the accuracy of porosity measurements by CT with the associated measurement uncertainty is evaluated using the reference standard.

  4. Air-filled porosity and permeability relationships during solid-state fermentation.

    Science.gov (United States)

    Richard, Tom L; Veeken, Adrie H M; de Wilde, Vinnie; Hamelers, H V M Bert

    2004-01-01

    An experimental apparatus was constructed to measure the structural parameters of organic porous media, i.,e. mechanical strength, air-filled porosity, air permeability, and the Ergun particle size. These parameters are critical to the engineering of aerobic bioconversion systems and were measured for a straw--manure mixture before and after 13 days of in-vessel composting. Porosity was measured using air pycnometry at four (day 0) and five (day 13) moisture levels, with each moisture level tested at a range of different densities. Tested wet bulk densities varied with moisture level, but dry bulk densities generally ranged from 100 to 200 kg m(-3). At each moisture/density combination, pressure drop was measured at airflow rates ranging from 0.001 to 0.05 m sec(-1), representing the range of airflow rates found in both intensive and extensive composting. Measured air-filled porosities were accurately predicted from measurements of bulk density, moisture, and organic matter content. Reductions in air-filled porosity at increasing moisture content were accompanied by an increase in permeability, apparently due to aggregations of fines. This aggregation was quantified by calculating an effective particle size from the Ergun permeability relationship, which increased from 0.0002 m at 50% moisture to 0.0021 m at 79% moisture. The range of airflow velocities reported in composting systems requires consideration of the second-order drag force term, particularly at velocities approaching 0.05 m s(-1) for the higher moisture treatments tested. Calculated permeabilities for the matrix ranged from 10(-10) to 10(-7) m2, varying with both air-filled porosity and moisture. Mechanical strength characterization provided a means to predict the effects of compaction on air-filled porosity and permeability of porous media beds. The results of this investigation extend porous media theory to the organic matrices common in solid-state fermentations and help build a framework for

  5. Full-waveform inversion of Crosshole GPR data: Implications for porosity estimation in chalk

    Science.gov (United States)

    Keskinen, Johanna; Klotzsche, Anja; Looms, Majken C.; Moreau, Julien; van der Kruk, Jan; Holliger, Klaus; Stemmerik, Lars; Nielsen, Lars

    2017-05-01

    The Maastrichtian-Danian chalk is a widely distributed hydrocarbon and groundwater reservoir rock in north-western Europe. Knowledge of lateral and vertical heterogeneity and porosity variation in this type of rock is essential, since they critically determine the reservoir properties. We have collected a densely sampled crosshole ground-penetrating radar (GPR) dataset from a highly heterogeneous section of the chalk and inverted it with a full-waveform inversion (FWI) approach. To date, successful crosshole FWI has only been reported for a handful of GPR field data, none of which include strongly heterogeneous environments like the one considered in this study. Testing different starting models shows that all FWI results converge to very similar subsurface structures indicating that the results are robust with regard to local variations in the permittivity starting models and are not very sensitive to the conductivity starting models. Compared to their ray-based counterparts, the obtained FWI models show significantly higher resolution and improved localization of fine-scale heterogeneity. The final FWI permittivity tomogram was converted to a bulk porosity model using the Complex Refractive Index Model (CRIM) and comparisons with plug sample porosities and televiewer image logs verify that variations in the obtained permittivity are related to facies and lithology changes. The inferred porosity varies from 30 to 54%, which is consistent with values in the chalk cores from the investigated boreholes and in agreement with other studies conducted in similar rocks onshore. Moreover, porosities vary significantly over scales of less than a meter both laterally and vertically. The FWI constrains porosity variation with decimeter scale resolution in our 5 m (horizontally) by 10 m (vertically) model section bridging the gap between what is measured on the core sample scale and the scale typical of hydrogeophysical field experiments conducted to characterize fluid flow in

  6. Variations in Multiscale (nano to mm) Porosity in the Eagle Ford Shale as a Function of Maturity through the Oil Window

    Science.gov (United States)

    Anovitz, L. M.; Cole, D. R.; Swift, A.; Sheets, J.; Elston, H. W.; Gutierrez, M. A.; Cook, A.; Chipera, S.; Littrell, K. C.; Mildner, D. F.; Wasbrough, M.

    2013-12-01

    Porosity and permeability are key variables that link the thermal-hydrologic, geomechanical and geochemical behavior in rock systems and are thus important input parameters for transport models. Recent neutron scattering studies have indicated that the scales of pore sizes in rocks extend over many orders of magnitude from nanometer pores with huge amounts of total surface area to large open fracture systems (multiscale porosity, cf. Anovitz et al., 2009, 2011, 2013a,b). However, despite a considerable amount of effort combining conventional rock petrophysics with more sophisticated neutron scattering and electron microscopy studies, the quantitative nature of this porosity in tight gas shales, especially at smaller scales and over larger rock volumes, remains largely unknown (Clarkson, 2011). We lack a quantitative understanding of the multiscale porosity regime (i.e., pore size, shape, and volume, pore size distribution, pore connectivity, pore wall roughness) in rocks. Nor is it understood how porosity is affected by regional variation, thermal changes across the oil window, and, most critically, hydraulic fracturing operations. In order to begin to provide a quantitative understanding of porosity at nanometer to core scales in these shale formations and how it relates to gas storage and recovery we have used a combination of small and ultrasmall angle neutron scattering measurments made on the GP-SANS instrument at ORNL/HFIR, and the NG3-SANS and BT5-USANS instruments and NIST/NCNR, with SEM/BSE and X-ray Computed Tomographic imaging to analyze the pore structure of both clay and carbonate-rich samples of the Eagle Ford Shale. The Eagle Ford Shale is a late Cretaceous unit underlying much of southeast Texas and probably adjacent sections of Mexico. It outcrops in an arc from north of Austin, through San Antonio and then west towards Kinney County. It is hydrocarbon rich, and buried portions straddle the oil window. The Eagle Ford is currently one of the most

  7. Saturated hydraulic conductivity and porosity within macroaggregates modified by tillage

    Energy Technology Data Exchange (ETDEWEB)

    Park, E.J.; Smucker, A.J.M. (MSU)

    2010-07-20

    Greater knowledge of intraaggregate porosity modifications by tillage conveys new information for identifying additional hydrologic, ion retention, and aggregate stability responses to specific management practices. Macroaggregates, 2 to 4, 4 to 6.3, and 6.3 to 9.5 mm across, were separated into multiple concentric layers and their porosities were determined. Saturated hydraulic conductivity (K{sub s}) of multiple aggregate fractions from two soil types subjected to conventional tillage (CT), no tillage (NT), and native forest (NF) soils were measured individually to identify the effects of tillage on aggregate structure, porosity, and K{sub s}. Intraaggregate porosities were the highest in NF aggregates. Greater porosities were identified in exterior layers of soil aggregates from all treatments. Lowest intraaggregate porosities were observed in the central regions of CT aggregates. Soil aggregates, 6.3 to 9.5 mm across, had the greatest total porosities, averaging 37.5% for both soil types. Long-term CT reduced intraaggregate porosities and K, within macroaggregates, of the same size fraction, from both the Hoytville silty clay loam and Wooster silt loam soil types. Values for K, of NF aggregates, 5.0 x 10{sup -5} cm s{sup -1}, were reduced 50-fold by long-term CT treatments of the Hoytville series. The K, values through Wooster aggregates from NF, 16.0 x 10{sup -5} cm s{sup -1}, were reduced 80-fold by long-term CT treatments. The K{sub s} values through NF and NT aggregates were positively correlated with their intraaggregate porosities (R{sup 2} = 0.84 for NF and R{sup 2} = 0.45 for NT at P < 0.005). Additional studies are needed to identify rates at which pore geometries within macroaggregates are degraded by CT or improved by NT.

  8. Effect of Travel Speed and Beam Focus on Porosity in Alloy 690 Laser Welds

    Science.gov (United States)

    Tucker, Julie D.; Nolan, Terrance K.; Martin, Anthony J.; Young, George A.

    2012-12-01

    Advances in laser welding technology, including fiber optic delivery and high power density, are increasing the applicability of this joining technique. The inherent benefits of laser welding include small heat-affected zones, minimal distortion, and limited susceptibility to cracking. These advantages are of special interest to next-generation nuclear power systems where welding solute-rich alloys is expected to increase. Alloy 690 (A690) is an advanced corrosion-resistant structural material used in many replacement components and in construction of new commercial power plants. However, the application of A690 is hindered by its difficult weldability using conventional arc welding, and laser welding is a promising alternate. This work studies the effects of travel speed and beam focus on porosity formation in partial penetration, autogenous A690 laser welds. Porosity has been characterized by light optical microscopy and x-ray computed tomography to quantify its percent volume in the welds. This work describes the tradeoff between weld penetration and defect density as a function of beam defocus and travel speed. Additionally, the role of shield gas in porosity formation is discussed to provide a mitigation strategy for A690 laser welding. A process map is provided that shows the optimal combinations of travel speed and beam defocus to minimize porosity and maximize weld penetration at a laser power of 4 kW.

  9. Recovery of Porosity and Permeability for High Plasticity Clays

    DEFF Research Database (Denmark)

    Krogsbøll, Anette; Foged, Niels Nielsen

    Clays, which have been loaded to a high stress level, will under certain conditions keep low porosity and permeability due to the high degree of compression. In some situations it seems that porosity and permeability will recover to a very high extent when the clay is unloaded. This seems...... to be the case for high plasticity clays that are uncemented, and with a high content of clay minerals, especially smectite. Oedometer tests on samples from the Paleogene period show that 80% or more of the compaction will recover when unloaded, and if unloaded to a stress lower than in situ stress level...... the clay will expand to an even higher porosity....

  10. A Permeability-Porosity Relationship for Surface Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Weir, G.J.; White, S.P.

    1995-01-01

    The changes to porosity and permeability resulting from surface deposition and early dissolution in an initial rhombohedral array of uniform spheres are calculated. Very rapid decreases of permeability result from early deposition, with 48% reduction predicted in permeability from 8% reduction in porosity. After deposition has caused about a 1% increase in the radii of the spherical array, relative permeability reductions vary approximately as the square of relative changes in porosity. These theoretical results are matched with experimental data of Ioti et al. and shown to be satisfactory in some cases, but for others, a more complex model of the porous medium is needed.

  11. The impact of kaolin dehydroxylation on the porosity and mechanical integrity of kaolin based ceramics using different pore formers

    Directory of Open Access Journals (Sweden)

    David O. Obada

    Full Text Available Thermally induced lattice defects in kaolin play a key role in the mechanical integrity of kaolin based ceramics during heat treatment due to their phase transformations. The effects of three types of pore formers (sawdust, styrofoam and powdery high density polyethylene on the porosity and mechanical integrity of kaolin based ceramics have been studied based on their batch formulations. The porosity of the ceramic bodies was experimentally determined, while the structure and chemistry of the materials were elucidated via X-ray diffraction (XRD, scanning electron microscopy (SEM, FTIR, DSC/TG/DTA, and zeta potential. The kaolin-based porous samples sintered at 1150 °C exhibited mullite phase transformation attributed to recrystallization effects. Morphologically, open pores were distributed on the sample surfaces due to larger pathways and available channels of eviction of the pore formers. Compressive strength decreased linearly as apparent porosity increased signifying its correlation. The compressive strength showed to be much more sensitive to defects created by dehydroxylation as micro cracks were observed on the sample with HDPE as pore former which could be as a result of large volume change accompanying phase transformations and sensitivity to the dehydroxylation phase. It is noted that the new pore former (HDPE used in this study produced ceramic bodies with porosity as high as 67% and hence the least compressive strength. Keywords: Porosity, Kaolin clay, Mechanical property, Lattice defects, Calcination

  12. Porosity and Mechanical Strength of an Autoclaved Clayey Cellular Concrete

    Directory of Open Access Journals (Sweden)

    P. O. Guglielmi

    2010-01-01

    Full Text Available This paper investigates the porosity and the mechanical strength of an Autoclaved Clayey Cellular Concrete (ACCC with the binder produced with 75 wt% kaolinite clay and 25 wt% Portland cement. Aluminum powder was used as foaming agent, from 0.2 wt% to 0.8 wt%, producing specimens with different porosities. The results show that the specimens with higher content of aluminum presented pore coalescence, which can explain the lower porosity of these samples. The porosities obtained with the aluminum contents used in the study were high (approximately 80%, what accounts for the low mechanical strength of the investigated cellular concretes (maximum of 0.62 MPa. Nevertheless, comparing the results obtained in this study to the ones for low temperature clayey aerated concrete with similar compositions, it can be observed that autoclaving is effective for increasing the material mechanical strength.

  13. Porosity-dependent fractal nature of the porous silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Rahmani, N.; Dariani, R. S., E-mail: dariani@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran, 1993893973 (Iran, Islamic Republic of)

    2015-07-15

    Porous silicon films with porosity ranging from 42% to 77% were fabricated by electrochemical anodization under different current density. We used atomic force microscopy and dynamic scaling theory for deriving the surface roughness profile and processing the topography of the porous silicon layers, respectively. We first compared the topography of bare silicon surface with porous silicon and then studied the effect of the porosity of porous silicon films on their scaling behavior by using their self-affinity nature. Our work demonstrated that silicon compared to the porous silicon films has the highest Hurst parameter, indicating that the formation of porous layer due to the anodization etching of silicon surface leads to an increase of its roughness. Fractal analysis revealed that the evolution of the nanocrystallites’ fractal dimension along with porosity. Also, we found that both interface width and Hurst parameter are affected by the increase of porosity.

  14. Permeability and porosity models of bi-fractal porous media

    Science.gov (United States)

    Tan, Xiao-Hua; Kui, Ming-Qing; Li, Xiao-Ping; Mao, Zheng-Lin; Xiao, Heng

    2017-11-01

    In previous studies, it is found that the frame and pore in porous media both possess the fractal geometric character. So the permeability and porosity models of bi-fractal porous media are derived based on the assumption that a porous media consists of fractal solid clusters and capillary bundles. The expressions of presented models are constituted by the fractal parameters of solid cluster and those of capillary bundle. Good agreement between model predictions and experimental data is obtained. This verifies the validity of the permeability and porosity models for bi-fractal porous media. The sensitive parameters that influence the permeability and porosity are specified, and their effects on the relationship between permeability and porosity are discussed.

  15. Influence of Chemical Composition on Porosity in Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Kucharčík L.

    2014-06-01

    Full Text Available Porosity is one of the major defects in aluminum castings, which results is a decrease of a mechanical properties. Porosity in aluminum alloys is caused by solidification shrinkage and gas segregation. The final amount of porosity in aluminium castings is mostly influenced by several factors, as amount of hydrogen in molten aluminium alloy, cooling rate, melt temperature, mold material, or solidification interval. This article deals with effect of chemical composition on porosity in Al-Si aluminum alloys. For experiment was used Pure aluminum and four alloys: AlSi6Cu4, AlSi7Mg0, 3, AlSi9Cu1, AlSi10MgCu1.

  16. Effects of Porosity and Thermal Treatment on Hydration of Mushrooms

    OpenAIRE

    Paudel, Ekaraj; Boom, R.M.; Sman, van der, R.G.M.

    2016-01-01

    In this study, hydration of mushroom as a porous food material has been studied considering their biphasic character. It consists of a solid phase that consists of intertwined hyphae and having cell walls with a swellable polymeric matrix and a pore phase made up by the space in between the hyphae. We have investigated the hydration of mushrooms as a function of initial porosity and thermal treatment. Variation in porosity is induced by the natural variation in the growth of mushroom. Porosit...

  17. The Albedo of Pervious Cement Concrete Linearly Decreases with Porosity

    OpenAIRE

    Rui Zhang; Guosheng Jiang; Jia Liang

    2015-01-01

    Pervious pavements have been advocated as a potential countermeasure to the urban heat island effect. To understand if pervious pavements stay cooler than conventional pavements, the albedo of the pervious concrete must be understood. This study measured the albedo of pervious concrete with different porosity. Four Portland cement concrete mixes were casted, using designed amounts of sand to vary the porosity of the pervious concrete samples. The samples were sliced and the spectral reflectan...

  18. Modulus Dependence on Large Scale Porosity of Powder Metallurgy Steel

    Science.gov (United States)

    Allison, P. G.; Horstemeyer, M. F.; Brown, H. R.

    2012-07-01

    This article compares the existing theoretical expressions for the porosity dependence on elastic constants to experimental data for a commercially available material, FC-0205 powder metallurgy (PM) steel. The modulus of compression, tension, effective torsion, and ultrasound-based data at varying porosity levels are plotted graphically against the theoretical expressions. An equation by McAdam ( J. Iron Steel Inst. Lond., 1950, 168, p 346) was able to most accurately predict the experimental data with the adjustment of only one material constant.

  19. Porosity Variation in Cenozoic and Upper Chalk from the Ontong Java Pleateau

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine

    1997-01-01

    Porosity was obtained from matrix- and intraparticle porosity assessed from image analysis of backscattered electron micrographs of 3000x and 300x magnification. Comparing porosity assessed from image analysis with porosity measured by index properties, it was seen that image analysis data at 3000x...... magnification overestimates the dominating phase where images are resolved well, because of transparency in the upper few microns of the sample. Thus image analysis porosity in the upper ooze interval (porosities more than 65%) show a good correspondence, because of the combined effect of porosity being...... the domination phase and insufficient resolution leading to porosity underestimation. In chalk samples (porosities around 50% or more) the lowest estimate of image analysis porosity corresponded because of the transparency, whereas in limestone samples (porosities less than 25%) highest image porosity estimate...

  20. Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control.

    Science.gov (United States)

    Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

    2014-01-01

    Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented.

  1. Numerical study of porosity in titanium dental castings.

    Science.gov (United States)

    Wu, M; Sahm, P R; Augthun, M; Spiekermann, H; Schädlich-Stubenrauch, J

    1999-09-01

    A commercial software package, MAGMASOFT (MAGMA Giessereitechnologie GmbH, Aachen, Germany), was used to study shrinkage and gas porosity in titanium dental castings. A geometrical model for two simplified tooth crowns connected by a connector bar was created. Both mold filling and solidification of this casting model were numerically simulated. Shrinkage porosity was quantitatively predicted by means of a built-in feeding criterion. The risk of gas pore formation was investigated using the numerical filling and solidification results. The results of the numerical simulations were compared with experiments, which were carried out on a centrifugal casting machine with an investment block mold. The block mold was made of SiO2 based slurry with a 1 mm thick Zr2 face coat to reduce metal-mold reactions. Both melting and casting were carried out under protective argon (40 kPa). The finished castings were sectioned and the shrinkage porosity determined. The experimentally determined shrinkage porosity coincided with the predicted numerical simulation results. No apparent gas porosity was found in these model castings. Several running and gating systems for the above model casting were numerically simulated. An optimized running and gating system design was then experimentally cast, which resulted in porosity-free castings. Copyright 1999 Kluwer Academic Publishers

  2. Quantifying porosity and permeability of fractured carbonates and fault rocks in natural groundwater reservoirs

    Science.gov (United States)

    Pirmoradi, Reza; Wolfmayr, Mariella; Bauer, Helene; Decker, Kurt

    2017-04-01

    This study presents porosity and permeability data for a suite of different carbonate rocks from two major groundwater reservoirs in eastern Austria that supply more than 60% of Vienna`s drinking water. Data includes a set of lithologically different, unfractured host rocks, fractured rocks with variable fracture intensities, and fault rocks such as dilation breccias, different cataclasites and dissolution-precipitation fault rocks. Fault rock properties are of particular importance, since fault zones play an important role in the hydrogeology of the reservoirs. The reservoir rocks are exposed at two major alpine karst plateaus in the Northern Calcareous Alps. They comprise of various Triassic calcareous strata of more than 2 km total thickness that reflect facies differentiation since Anisian times. Rocks are multiply deformed resulting in a partly dense network of fractures and faults. Faults differ in scale, fault rock content, and fault rock volumes. Methods used to quantify the porosity and permeability of samples include a standard industry procedure that uses the weight of water saturated samples under hydrostatic uplift and in air to determine the total effective (matrix and fracture) porosity of rocks, measurements on plugs with a fully automated gas porosity- and permeameter using N2 gas infiltrating plugs under a defined confining pressure (Coreval Poro 700 by Vinci technologies), and percolation tests. The latter were conducted in the field along well known fault zones in order to test the differences in fractured rock permeability in situ and on a representative volume, which is not ensured with plug measurements. To calculate hydraulic conductivity by the Darcy equation the measured elapsed time for infiltrating a standard volume of water into a small borehole has been used. In general, undisturbed host rock samples are all of low porosity (average around 1%). The open porosity of the undisturbed rocks belonging to diverse formations vary from 0

  3. Increasing Magnetoplasticity in Polycrystalline Ni-Mn-Ga by Reducing Internal Constraints through Porosity

    Science.gov (United States)

    Boonyongmaneerat, Yuttanant; Chmielus, Markus; Dunand, David C.; Müllner, Peter

    2007-12-01

    Foams with 55% and 76% open porosity were produced from a Ni-Mn-Ga magnetic shape-memory alloy by replication casting. These polycrystalline martensitic foams display a fully reversible magnetic-field-induced strain of up to 0.115% without bias stress, which is about 50 times larger than nonporous, fine-grained Ni-Mn-Ga. This very large improvement is attributed to the bamboolike structure of grains in the foam struts which, due to reduced internal constraints, deform by magnetic-field-induced twinning more easily than equiaxed grains in nonporous Ni-Mn-Ga.

  4. Etude de la diagraphie neutron du granite de Beauvoir. Effet neutron des altérations et de la matrice du granite. Calibration granite. Porosité totale à l'eau et porosité neutron Analysis of the Beauvoir Granite Neutron Log. Neutron Effect of Alterations and of the Granite Matrix. Granite Calibration. Total Water Porosity and Neutron Porosity

    Directory of Open Access Journals (Sweden)

    Galle C.

    2006-11-01

    carottes (n. Nous montrons que, pour le granite de Beauvoir, l'effet neutron de la matrice est important (en moyenne proche de 7% et ne peut être négligé lorsque l'on mesure des porosités voisines de 0,5% sur carottes. La calibration de l'outil neutron dans le granite et non pas dans des calcaires est d'autre part capitale quant à la précision quantitative des résultats. This article describes the research done on the Beauvoir granite (Echassières GPF 1 borehole, French Massif Central range. The aim of this project was to obtain representative values of the water saturation (n total free water porosity of the Beauvoir granite from PorosityN neutron porosity (BRGM neutron log. The exact knowledge of the porosity of a crystalline block is effectively fundamental to determine its possibilities for being used as a waste storage site. With this goal, neutron logging provides indispensable information concerning the characterization of a porous medium. Our procedure was experimental, and we tried to go more deeply into various problems linked to the use of neutron logging in a granitic rock. Two main factors governed the neutron response : (i the hydrogen concentration of the formation (free water and combined water of various minerals and (ii the presence of absorber elements with a large capture cross-section such as gadolinium, cadmium, boron as well as lithium for the Beauvoir granite. After measuring the Beauvoir granite n total (free water porosity on core samples, we evaluated the combined water content of each sample tested on the basis of fire loss tests on rock powder at 900°C. From the hydrogen atoms volumic concentration, we determined a hydrogen index that we directly converted into the PorosityN(OH- neutron porosity, (by definition, pure water at 20°C has a hydrogen index of 1 which is equivalent to a 100% porosity. For the Beauvoir granite, the matrix combined water represents an average neutron porosity (Table 1 of about 4%. In the second phase, we used

  5. Computation of porosity and water content from geophysical logs, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, P.H.

    1996-12-31

    Neutron and density logs acquired in boreholes at Yucca Mountain, Nevada are used to determine porosity and water content as a function of depth. Computation of porosity requires an estimate of grain density, which is provided by core data, mineralogical data, or is inferred from rock type where neither core nor mineralogy are available. The porosity estimate is merged with mineralogical data acquired by X-ray diffraction to compute the volumetric fractions of major mineral groups. The resulting depth-based portrayal of bulk rock composition is equivalent to a whole rock analysis of mineralogy and porosity. Water content is computed from epithermal and thermal neutron logs. In the unsaturated zone, the density log is required along with a neutron log. Water content can also be computed from dielectric logs, which were acquired in only a fraction of the boreholes, whereas neutron logs were acquired in all boreholes. Mineralogical data are used to compute a structural (or bound) water estimate, which is subtracted from the total water estimate from the neutron-density combination. Structural water can be subtracted only from intervals where mineralogical analyses are available; otherwise only total water can be reported. The algorithms and procedures are applied to logs acquired during 1979 to 1984 at Yucca Mountain. Examples illustrate the results. Comparison between computed porosity and core measurements shows systematic differences ranging from 0.005 to 0.04. These values are consistent with a sensitivity analysis using uncertainty parameters for good logging conditions. Water content from core measurements is available in only one borehole, yielding a difference between computed and core-based water content of 0.006.

  6. Cognitive-behavioral therapy: How medical providers can increase patient and family openness and access to evidence-based multimodal therapy for pediatric migraine

    Science.gov (United States)

    Ernst, Michelle M.; O’Brien, Hope; Powers, Scott W.

    2015-01-01

    While evidence supports the recommendation for cognitive behavioral therapy (CBT) for pediatric migraine, few children actually receive this evidence-based intervention. In this article we briefly review the most recent empirical evidence supporting CBT. We then identify both provider/system-related barriers as well as patient-related barriers. Finally, we provide practical solutions to addressing these barriers in the service of facilitating children receiving optimal comprehensive management of their headaches. PMID:26198185

  7. Porosity and packing of Holocene river, dune, and beach sands

    Energy Technology Data Exchange (ETDEWEB)

    Atkins, J.E. (Conoco, Inc., Oklahoma City, OK (United States)); McBride, E.F. (Univ. of Texas, Austin (United States))

    1991-03-01

    The porosity and packing of 174 samples of well-sorted surficial and shallowly buried (to 17 m), unconsolidated Holocene sands were determined by point counting the upper surface of thin sections of epoxy-impregnated samples in reflected light. Average depositional porosity for 124 surficial beach sands, river point-bar and braid-bar sands, and eolian dune sands is between 40% and 58%. Beach sands exhibit an average packing value (contact index = CI) of 0.79, river sands an average IC of 0.91, and eolian dune sands an average CI of 1.02. Packing gets tighter with depth, but the authors found no decrease in porosity with depth for river and beach sands buried to 17 m. Thus, packing is more sensitive to small changes in fabric than is porosity. Beach sands typically contain 5.5% oversized pores (OSP), river sands 3.8% OSP, and eolian dune sands 4.0% OSP. Most OSP are packing defects rather than dissolution pores, although trapped air bubbles are common in some beach sands. OSP decrease linearly with depth to 17 m, our deepest sample. Extrapolation of our data indicates that they will be destroyed at a depth less than 100 m. Significant differences in porosity, oversized-pore, and packing values exist between most point-bar and braid-bar deposits and between two heavily sampled point bars, but no significant differences in these values exist when braid-bar sands are compared to other braid-bar sands. Sands form different beaches have significant differences in porosity, oversized pores, and packing. The average porosity is 46% for eolian ripple strata, 50% for grain-fall strata, and 51% for grain-flow strata. Ripple strata are tighter packed than grain-fall and grain-flow strata.

  8. Minimally invasive esophagectomy provides significant survival advantage compared with open or hybrid esophagectomy for patients with cancers of the esophagus and gastroesophageal junction.

    Science.gov (United States)

    Palazzo, Francesco; Rosato, Ernest L; Chaudhary, Asadulla; Evans, Nathaniel R; Sendecki, Jocelyn A; Keith, Scott; Chojnacki, Karen A; Yeo, Charles J; Berger, Adam C

    2015-04-01

    Minimally invasive esophagectomy (MIE) is increasingly being used to treat patients with cancer of the esophagus and gastroesophageal junction. We previously reported that oncologic efficacy may be improved with MIE compared with open or hybrid esophagectomy (OHE). We compared survival of patients undergoing MIE and OHE. Our contemporary series of patients who underwent MIE (2008 to 2013) was compared with a cohort undergoing OHE (3-hole [n = 39], Ivor Lewis [n = 16], hybrid [n = 13], 2000 to 2013). Summary statistics were calculated by operation type; Kaplan-Meier methods were used to compare survival. Cox regression was used to assess the impact of operation type (MIE vs OHE) on mortality, adjusting for age, sex, total lymph nodes, lymph node ratio (LNR), neoadjuvant chemoradiotherapy (CRT), and stage. The MIE (n = 104) and OHE (n = 68) groups were similar with respect to age and sex. The MIE group tended to have higher BMI, earlier stage disease, and was less likely to receive CRT. The MIE group experienced lower operative mortality (3.9% vs 8.8%, p = 0.35) and significantly fewer major complications. Five-year survival between groups was significantly different (MIE, 64%, OHE, 35%, p analysis demonstrated that patients undergoing OHE had a significantly worse survival compared with MIE independent of age, LNR, CRT, and pathologic stage (hazard ratio 2.00, p = 0.019). This study supports MIE for EC as a superior procedure with respect to overall survival, perioperative mortality, and severity of postoperative complications. Several biases may have affected these results: earlier stage in the MIE group and disparity in timing of the procedures. These results will need to be confirmed in future prospective studies with longer follow-up. Copyright © 2015 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  9. Testing Mercury Porosimetry with 3D Printed Porosity Models

    Science.gov (United States)

    Hasiuk, F.; Ewing, R. P.; Hu, Q.

    2014-12-01

    Mercury intrusion porosimetry is one of the most widely used techniques to study the porous nature of a geological and man-made materials. In the geosciences, it is commonly used to describe petroleum reservoir and seal rocks as well as to grade aggregates for the design of asphalt and portland cement concretes. It's wide utility stems from its ability to characterize a wide range of pore throat sizes (from nanometers to around a millimeter). The fundamental physical model underlying mercury intrusion porosimetry, the Washburn Equation, is based on the assumption that rock porosity can be described as a bundle of cylindrical tubes. 3D printing technology, also known as rapid prototyping, allows the construction of intricate and accurate models, exactly what is required to build models of rock porosity. We evaluate the applicability of the Washburn Equation by comparing properties (like porosity, pore and pore throat size distribution, and surface area) computed on digital porosity models (built from CT data, CAD designs, or periodic geometries) to properties measured via mercury intrusion porosimetry on 3D printed versions of the same digital porosity models.

  10. Dual integral porosity shallow water model for urban flood modelling

    Science.gov (United States)

    Guinot, Vincent; Sanders, Brett F.; Schubert, Jochen E.

    2017-05-01

    With CPU times 2 to 3 orders of magnitude smaller than classical shallow water-based models, the shallow water equations with porosity are a promising tool for large-scale modelling of urban floods. In this paper, a new model formulation called the Dual Integral Porosity (DIP) model is presented and examined analytically and computationally with a series of benchmark tests. The DIP model is established from an integral mass and momentum balance whereby both porosity and flow variables are defined separately for control volumes and boundaries, and a closure scheme is introduced to link control volume- and boundary-based flow variables. Previously developed Integral Porosity (IP) models were limited to a single set of flow variables. A new transient momentum dissipation model is also introduced to account for the effects of sub-grid scale wave action on porosity model solutions, effects which are validated by fine-grid solutions of the classical shallow-water equations and shown to be important for achieving similarity in dam-break solutions. One-dimensional numerical test cases show that the proposed DIP model outperforms the IP model, with significantly improved wave propagation speeds, water depths and discharge calculations. A two-dimensional field scale test case shows that the DIP model performs better than the IP model in mapping the floods extent and is slightly better in reproducing the anisotropy of the flow field when momentum dissipation parameters are calibrated.

  11. Porosity Distribution in Composite Structures with Infrared Thermography

    Directory of Open Access Journals (Sweden)

    Cinzia Toscano

    2013-01-01

    Full Text Available Composite structures are increasingly used in the transport industry especially in the aeronautical sector thanks to their favorable strength-to-weight ratio with respect to metals. However, this is true if the final part is defects free and complies with quality requirements. A main weakness in composites is porosity, which is likely to be introduced during manufacturing processes and which may knock down the material characteristics affecting its performance in service. Porosity plays a key role in sandwich structures, which involve novel metal foams as core, since the foam performance strongly depends on size and distribution of pores. The determination of porosity is mostly attained by destructive methods, which supply only a general indication linked to the production part number. Conversely, composites may entail local significant variation of porosity, which may be discovered only with effective nondestructive techniques. The attention of the present work is focused on the possibility to use infrared thermography to get information about the amount and distribution of porosity. In particular, two techniques: flash thermography and lock-in thermography are used to comply with requirements of both monolithic composites and metal foams.

  12. AGRIS: providing access to agricultural research data exploiting open data on the web [v1; ref status: indexed, http://f1000r.es/599

    Directory of Open Access Journals (Sweden)

    Fabrizio Celli

    2015-05-01

    Full Text Available AGRIS is the International System for Agricultural Science and Technology. It is supported by a large community of data providers, partners and users. AGRIS is a database that aggregates bibliographic data, and through this core data, related content across online information systems is retrieved by taking advantage of Semantic Web capabilities. AGRIS is a global public good and its vision is to be a responsive service to its user needs by facilitating contributions and feedback regarding the AGRIS core knowledgebase, AGRIS’s future and its continuous development. Periodic AGRIS e-consultations, partner meetings and user feedback are assimilated to the development of the AGRIS application and content coverage. This paper outlines the current AGRIS technical set-up, its network of partners, data providers and users as well as how AGRIS’s responsiveness to clients’ needs inspires the continuous technical development of the application. The paper concludes by providing a use case of how the AGRIS stakeholder input and the subsequent AGRIS e-consultation results influence the development of the AGRIS application, knowledgebase and service delivery.

  13. A comparison of porosity analysis using 2D stereology estimates and 3D serial sectioning for additively manufactured Ti 6Al 2Sn 4Zr 2Mo alloy; Vergleich der Porositaetsanalyse einer Ti 6Al 2Sn 4Zr 2Mo-Legierung aus additiver Fertigung mittels stereologischer Schaetzungen (2D) und mit Serienschnitten (3D)

    Energy Technology Data Exchange (ETDEWEB)

    Ganti, Satya R.; Velez, Michael A.; Geier, Brian A.; Hayes, Brian J.; Turner, Bryan J.; Jenkins, Elizabeth J. [UES Inc., Dayton, OH (United States)

    2017-02-15

    Porosity is a typical defect in additively manufactured (AM) parts. Such defects limit the properties and performance of AM parts, and therefore need to be characterized accurately. Current methods for characterization of defects and microstructure rely on classical stereological methods that extrapolate information from two dimensional images. The automation of serial sectioning provides an opportunity to precisely and accurately quantify porosity in three dimensions in materials. In this work, we analyzed the porosity of an additively manufactured Ti 6Al 2Sn 4Zr 2Mo sample using Robo-Met.3D {sup registered}, an automated serial sectioning system. Image processing for three dimensional reconstruction of the serial-sectioned two dimensional images was performed using open source image analysis software (Fiji/ImageJ, Dream.3D, Paraview). The results from this 3D serial sectioning analysis were then compared to classical 2D stereological methods (Saltykov stereological theory). We found that for this dataset, the classical 2D methods underestimated the porosity size and distributions of the larger pores; a critical attribute to fatigue behavior of the AM part. The results suggest that acquiring experimental data with equipment such as Robo-Met.3D {sup registered} to measure the number and size of particles such as pores in a volume irrespective of knowing their shape is a better choice.

  14. Processing and characterization of high porosity aerogel films

    Energy Technology Data Exchange (ETDEWEB)

    Hrubesh, L.W.; Poco, J.F.

    1994-11-22

    Aerogels are highly porous solids having unique morphology among materials because both the pores and particles making up the material have sizes less than wavelengths of visible light. Such a unique morphology modifies the normal molecular transport mechanisms within the material, resulting in exceptional thermal, acoustical, mechanical, and electrical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. Special methods are required to make aerogel films with high porosity. In this paper, we discuss the special conditions needed to fabricate aerogel films having porosities greater than 75% and we describe methods of processing inorganic aerogel films having controllable thicknesses in the range 0.5 to 200 micrometers. We report methods and results of characterizing the films including thickness, refractive index, density (porosity), and dielectric constant. We also discuss results of metallization and patterning on the aerogel films for applications involving microminiature electronics and thermal detectors.

  15. Evaluation of porosity in Al alloy die castings

    Directory of Open Access Journals (Sweden)

    M. Říhová

    2012-01-01

    Full Text Available Mechanical properties of an Al-alloy die casting depend significantly on its structural properties. Porosity in Al-alloy castings is one of the most frequent causes of waste castings. Gas pores are responsible for impaired mechanical-technological properties of cast materials. On the basis of a complex evaluation of experiments conducted on AlSi9Cu3 alloy samples taken from the upper engine block which was die- cast with and without local squeeze casting it can be said that castings manufactured without squeeze casting exhibit maximum porosity in the longitudinal section. The area without local squeeze casting exhibits a certain reduction in mechanical properties and porosity increased to as much as 5%. However, this still meets the norms set by SKODA AUTO a.s.

  16. [Improvement and application of digitized measure on shelterbelt porosity].

    Science.gov (United States)

    Guan, Wenbin; Li, Chunping; Li, Shifeng; Fan, Zhiping; Xie, Chunhua

    2002-06-01

    Based on the lots of investigation on farmland shelterbelts, we used digital camera to take pictures of shelterbelt and apply CIAS software to improve "digital image processing" for determining shelterbelt porosity so as to thoroughly analyze the rule of porosity in farmland shelterbelts. Compared with the old digital image processing, the improved method possesses high accuracy, and it is more economical and more convenient to apply. The relationship between porosity of shelterbelts (beta) and relative clear bole height (x) can be expressed as beta = 0.672x0.469 (r = 0.9851, r0.01 = 0.4073, 0 better than the rectangle one among the same tree species. UPPU and SPPS of mixed structure have the optimal effect in popular-willow-elm mixed shelterbelts.

  17. Limitation of Shrinkage Porosity in Aluminum Rotor Die Casting

    Science.gov (United States)

    Kim, Young-Chan; Choi, Se-Weon; Kim, Cheol-Woo; Cho, Jae-Ik; Lee, Sung-Ho; Kang, Chang-Seog

    Aluminum rotor prone to have many casting defects especially large amount of air and shrinkage porosity, which caused eccentricity, loss and noise during motor operation. Many attempts have been made to develop methods of shrinkage porosity control, but still there are some problems to solve. In this research, the process of vacuum squeeze die casting is proposed for limitation of defects. The 6 pin point gated dies which were in capable of local squeeze at the end ring were used. Influences of filling patterns on HPDC were evaluated and the important process control parameters were high injection speed, squeeze length, venting and process conditions. By using local squeeze and vacuum during filling and solidification, air and shrinkage porosity were significantly reduced and the feeding efficiency at the upper end ring was improved 10%. As a result of controlling the defects, the dynamometer test showed improved motor efficiency by more than 4%.

  18. Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

    2009-09-27

    Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

  19. Modified porosity rate frost heave model and tests verification

    Science.gov (United States)

    Ji, Zhi-qiang; Xu, Xue-yan

    2008-11-01

    To avoid the complexity of modeling frost heave from microscope, porosity rate function has been used in predication of frost heave phenomenon. The approach explored in this paper is based on frost heave tests and the concept of the segregated potential which has been widely accepted by researchers in order to find the proper form of the porosity rate function. In the frozen fringe the porosity rate function was derived: n•=Be(-aPe) (gradT)2 (1-n) , (Tstests were carried out to verify the model, and the comparison between test results and analog results shows that the modified model is efficient for the prediction of frost heave, and it can be used in engineering practice.

  20. Chalk porosity and sonic velocity versus burial depth

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Gommesen, Lars; Krogsbøll, Anette Susanne

    2008-01-01

    but not pore-structure stiffening cementation in this presumably water-wet chalk. These results should improve the modeling of chalk background velocity for seismic inversion analysis. When describing the porosity-reducing process, pore-volume compressibility should probably be disregarded when correcting...... so that smectite-bearing chalk has a high Poisson's ratio in the water-saturated case, but a low value in the dry case. Oil-bearing chalk has up to 25 units higher porosity than water-saturated chalk at similar depth but similar velocity, probably because hydrocarbons prevent pore-filling cementation...

  1. Modeling the Relationship Between Porosity and Permeability During Oxidation of Ablative Materials

    Science.gov (United States)

    Thornton, John M.; Panerai, Francesco; Ferguson, Joseph C.; Borner, Arnaud; Mansour, Nagi N.

    2017-01-01

    The ablative materials used in thermal protection systems (TPS) undergo oxidation during atmospheric entry which leads to an in-depth change in both permeability and porosity. These properties have a significant affect on heat transfer in a TPS during entry. X-ray micro-tomography has provided 3D images capturing the micro-structure of TPS materials. In this study, we use micro-tomography based simulations to create high-fidelity models relating permeability to porosity during oxidation of FiberForm, the carbon fiber preform of the Phenolic Impregnated Carbon Ablator (PICA) often used as a TPS material. The goal of this study is to inform full-scale models and reduce uncertainty in TPS modeling.

  2. Timing of porosity destruction related to pressure-solution in limestones

    Science.gov (United States)

    Beaudoin, Nicolas; Koehn, Daniel; Aharonov, Einat; Boyce, Adrian; Billi, Andrea; Hamilton, Andrea

    2017-04-01

    Among effects that affect sedimentary rocks during diagenesis, pressure-solution has a very strong impact on the physical properties of rocks such as porosity and permeability. Intergranular pressure-solution results in rough or wavy surfaces called stylolites, which are very common in sedimentary basins, especially in limestone. According to the opening of the system, dissolved material can precipitate locally, leading to the destruction of the porosity around the stylolite. That can namely occur during the development of sedimentary stylolites, when no fracture of fault can allow dissolved material to flow away before precipitating again. This contribution aims at unravelling the depth at which the material dissolved during compaction precipitated in the open porosity, adding new data to discuss when pressure-solution starts to be an efficient mechanism of deformation in limestone during strata burial in sedimentary basins. We report the results of the study of cements that fill the fractures developed at the tips of stylolites in a sample of dolostone from the Jurassic Calcare Massiccio formation, coming from the Umbria-Marche area (Italy). The fractures developed from stylolite-induced stress, and the filling cements' oxygen and carbon isotopic values range between 10.6‰ to -6.1‰ PDB and -8.2‰ to -0.6‰ PDB, respectively. Considering a closed system, we use fractionation equations to convert δ18O values into temperature, which shows that the material put in solution during pressure-solution precipitated at a temperature ranging from 18°C to 39°C. Temperature range and geothermal gradient estimates suggest that the mechanism of pressure-solution actually was primarily active at depth as low as 1 km. In the studied sample, up to 18% of the original volume has been dissolved on stylolites, and that volume loss would have occurred in the first 2 km of the burial history. This natural example feeds the growing body of evidence that stylolites can start

  3. Porosity of free boundaries in the obstacle problem for quasilinear ...

    Indian Academy of Sciences (India)

    Indian Acad. Sci. (Math. Sci.) Vol. 123, No. 3, August 2013, pp. 373–382. c Indian Academy of Sciences. Porosity of free boundaries in the obstacle problem ... 2School of Mathematical Sciences, University of Electronic Science and Technology of China, Chengdu ... conditions for some positive constants γ0,γ1, namely. N. ∑.

  4. Relating wood properties to handsheet porosity and mechanical strength

    CSIR Research Space (South Africa)

    Maharaj, S

    2006-11-01

    Full Text Available to hand- sheet porosity and mechanical strength S. Maharaj1,3, J. Wesley-Smith2 and T. Bush3 1School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban, 4041 2Electron Microscope Unit, University of KwaZulu-Natal, Durban...

  5. Tuning porosity via control of interpenetration in a zinc isonicotinate ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 5. Tuning porosity via control of interpenetration in a zinc isonicotinate metal organic framework. Shyamapada Nandi Ramanathan Vaidhyanathan. Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1393-1398 ...

  6. A dual porosity model of nutrient uptake by root hairs

    KAUST Repository

    Zygalakis, K. C.

    2011-08-09

    Summary: • The importance of root hairs in the uptake of sparingly soluble nutrients is understood qualitatively, but not quantitatively, and this limits efforts to breed plants tolerant of nutrient-deficient soils. • Here, we develop a mathematical model of nutrient uptake by root hairs allowing for hair geometry and the details of nutrient transport through soil, including diffusion within and between soil particles. We give illustrative results for phosphate uptake. • Compared with conventional \\'single porosity\\' models, this \\'dual porosity\\' model predicts greater root uptake because more nutrient is available by slow release from within soil particles. Also the effect of soil moisture is less important with the dual porosity model because the effective volume available for diffusion in the soil is larger, and the predicted effects of hair length and density are different. • Consistent with experimental observations, with the dual porosity model, increases in hair length give greater increases in uptake than increases in hair density per unit main root length. The effect of hair density is less in dry soil because the minimum concentration in solution for net influx is reached more rapidly. The effect of hair length is much less sensitive to soil moisture. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  7. [Aortobifemoral prostheses with "0" porosity. Results after 2 years' experience].

    Science.gov (United States)

    Escudero, J R; Llagostera, S; Riambau, V; Latorre, E; Upegui, L; Pastor, O; Viver, E

    1990-01-01

    During the last years diverse types of Dacron prosthesis without porosity (because to be impregnated by different materials) have appeared. In the presented study, outcomes from three different types of prosthesis (differentiated by the impregnated material) were evaluated and a comparison with classical prosthesis was made.

  8. Estimation of porosity and hydraulic conductivity of shallow ...

    African Journals Online (AJOL)

    In this study, two theoretical methods based respectively on Archie-Kozeny equations and Ohm's-Darcy's laws were used to determine porosity and hydraulic conductivity of shallow aquifer in Yenagoa, Southern Nigeria. Fourteen Vertical Electrical Soundings (VES) using the Schlumberger configuration were carried out ...

  9. Effects of sintering temperature on the density and porosity

    African Journals Online (AJOL)

    2013-03-01

    Mar 1, 2013 ... Abstract. Effects of sintering temperature on the density and porosity of sodium chloride preforms for alu- minium foam manufacturing have been investigated. Cold pressed salt preforms were sintered at. 730Й, 760Й and 790Й and different times ranging between 6- 18 hours in a carbolite furnace at.

  10. Effects of Sintering Temperature on the Density And Porosity of ...

    African Journals Online (AJOL)

    Effects of sintering temperature on the density and porosity of sodium chloride preforms for alu- minium foam manufacturing have been investigated. Cold pressed salt preforms were sintered at 30, 760 and 790 and di erent times ranging between 6- 18 hours in a carbolite furnace at a heating rate of 5/minute. The Results of ...

  11. Measurements of the evolution of porosity in a mushy layer

    Science.gov (United States)

    Jahrling, Katia; Tait, Stephen

    1996-09-01

    We suggest improvements to an experimental technique designed to make local measurements of liquid volume fraction, or porosity, in a mushy layer that forms during dynamic solidification of a multicomponent melt. In a set of control experiments we measured the electrical resistance of a medium of known porosity in which the solid particles were Fontainebleau sand, and the electrolytes were aqueous solutions of ammonium chloride. The results confirm that an appropriate description can be obtained using Archie's law with a cementation exponent of 1.5. In a second set of experiments we solidified aqueous solutions of ammonium chloride by cooling from below under conductive conditions. The solid phase formed was ice with a plate-like morphology, and we compared values of porosity obtained from the electrical measurements with those deduced from temperature measurements assuming local thermodynamic equilibrium. The results indicate that this progressively solidifying porous medium can also be described by Archie's law, and good agreement between electrical and thermal porosities is obtained for a cementation exponent of 1.72. We interpret this higher value as implying a higher tortuosity for this porous medium when compared with that made of Fontainebleau sand.

  12. Direct synthesis of metal nanoparticles with tunable porosity

    NARCIS (Netherlands)

    Detsi, Eric; Punzhin, Sergey; Onck, Patrick R.; De Hosson, Jeff Th. M.

    2012-01-01

    Herein, we report a facile one-step synthesis route of porous bimetallic Au-Ag nanoparticles involving two parallel processes: alloying during nanocrystal growth and dealloying via galvanic replacement reaction. Further, we show that porosity in these nanoparticles can be tuned via their alloy

  13. Porosity and compaction trend in Okan field (Western Niger Delta ...

    African Journals Online (AJOL)

    The main hydrocarbon trap results from vertical stacking of porous reservoirs sands while the stratigraphic trap is evident from reservoir Pinchouts. Global Journal of Pure and Applied Sciences Volume , No 1 January (2001) pp. 91-96. KEY WORDS: Porosity, Reservoir, Sedimentation, Overpressure, Hydrocarbon.

  14. Compaction and Porosity Based Pore Pressure Prediction in the ...

    African Journals Online (AJOL)

    Three wells of the “Cappe” Field in the offshore part of the Coastal Swamp depobelt I, Niger Delta, were evaluated primarily to determine the impact of compaction on reservoir quality and to determine possible over-pressured zones in the Benin and Agbada formations. Sandstone porosity-depth plots of the three wells show ...

  15. Mechanisms and mechanics of porosity formation in ductile iron castings

    Directory of Open Access Journals (Sweden)

    M. Perzyk

    2007-12-01

    Full Text Available Shrinkage defects in ductile iron castings can be of two basic types: shrinkage cavities associated with the liquid contraction prior to the expansion period of the iron as well as the porosity, which may appear even if the liquid shrinkage is fully compensated. In the present paper two possible mechanisms of the porosity are presented and analyzed. The first one is the Karsay’s mechanism based on the secondary shrinkage concept. The second one is the mechanism acting during the expansion period of the iron, first suggested by Ohnaka and co-authors and essentially modified by the present authors. The mechanical interactions between casting and mould are determined for the both mechanisms. Their analysis leads to the conclusion, that porosity forms during expansion period of the melt. The direct cause is the negative pressure which appears in the central part of the casting due to the differences in expansion coefficients of the fast cooling surface layer and slow cooling inner region. Observations concerning feeding behavior of ductile iron castings, based on this mechanism, agree well with industrial practice. The secondary shrinkage is not only needless to induce the porosity, but the corresponding mechanism of its occurrence, proposed by Karsay, does not seem to be valid.

  16. The porosity in a fluidized bed heat transfer model

    NARCIS (Netherlands)

    Visser, G; Visser, G.; Valk, M.

    1993-01-01

    A mathematical model of heat transfer between a fluidized bed and an immersed surface and a model of gas flow and porosity, both recently published, were combined and further modified in the area of low velocities where the particle convective component of heat transfer is low or neglectable.

  17. Understanding age-induced cortical porosity in women

    DEFF Research Database (Denmark)

    Andreasen, Christina Møller; Delaisse, Jean-Marie; van der Eerden, Bram C J

    2018-01-01

    of a histomorphometric analysis of sections of iliac bone specimens from 35 women (age 16-78 years). Firstly, the study shows that the aging-induced cortical porosity reflects an increased pore size rather than an increased pore density. Secondly, it establishes a novel histomorphometric classification of the pores...

  18. Increased cortical porosity in women with hip fracture.

    Science.gov (United States)

    Sundh, D; Nilsson, A G; Nilsson, M; Johansson, L; Mellström, D; Lorentzon, M

    2017-05-01

    Hip fractures cause increased mortality and disability and consume enormous healthcare resources. Only 46% of hip fracture patients have osteoporosis at the total hip according to dual-energy X-ray absorptiometry (DXA) measurement. Cortical porosity increases with ageing and is believed to be important for bone strength. To investigate whether older women with hip fracture have higher cortical porosity than controls, and if so whether this difference is independent of clinical risk factors and areal bone mineral density (aBMD). From an ongoing population-based study, we identified 46 women with a prevalent X-ray-verified hip fracture and 361 control subjects without any fractures. aBMD was measured with DXA. High-resolution peripheral quantitative computed tomography was used to measure bone microstructure at the standard (ultradistal) site and at 14% (distal) of the tibial length. Women with a previous hip fracture had lower aBMD at the femoral neck (-11.8%) and total hip (-14.6%) as well as higher cortical porosity at the ultradistal (32.1%) and distal (29.3%) tibia compared with controls. In multivariable logistic regression analysis, with adjustment for covariates (age, height, weight, smoking, calcium intake, physical activity, walk time, oral glucocorticoids, parental hip fracture, rheumatoid arthritis, previous fall, current bisphosphonate treatment and femoral neck aBMD), cortical porosity at the ultradistal [odds ratio per standard deviation increase (95% confidence interval) 2.61 (1.77-3.85)] and distal [1.57 (1.12-2.20)] sites was associated with prevalent hip fracture. Cortical porosity was associated with prevalent hip fracture in older women independently of femoral neck aBMD and clinical risk factors. © 2017 The Authors. Journal of Internal Medicine published by John Wiley & Sons Ltd on behalf of Association for Publication of The Journal of Internal Medicine.

  19. Effect of Fin Porosity on Wake Geometry for Flapping Fins at Intermediate Reynolds Number

    Science.gov (United States)

    Chen, J.; Xia, B.; Krueger, P. S.

    2017-11-01

    Low aspect ratio flapping fins generate interesting 3-dimensional flow structures as has been observed, for example, in studies of fish swimming. As the Reynolds number is reduced, the exact geometry of the fin is less important and even certain amounts of porosity might be allowed without significantly affecting propulsive performance. These effects are investigated experimentally using flapping rectangular fins of aspect ratio 2 at Reynolds numbers in the range 100 - 1000. The experiments were conducted using a water tunnel to supply the free stream flow and the fin flapping parameters were set to provide a Strouhal number (based on amplitude of the fin tip motion) in the range 0.15 - 0.35. Phase-averaged measurements were made of the 3-dimensional, volumetric flow field, allowing visualization of the typical shed vortex structure behind the fin and calculation of time averaged thrust and propulsive efficiency. Results comparing the flow structure in the fin wake and the resulting propulsive performance will be presented for several fins with different planform porosities where the porosities are set using arrays of holes in the fins. This material is based on the work supported by the National Science Foundation under Grant No. 1510707.

  20. Porosity of an Anhydrous Chondritic Interplanetary Dust Particle

    Science.gov (United States)

    Strait, M. M.; Thomas, K. L.; McKay, D. S.

    1995-09-01

    Determination of the density and porosity of Interplanetary Dust Particles (IDPs) is important in the dynamics of collisional and orbital evolution of small-sized particles. These measurements are also useful to suggest possible sources for IDPs based on comparisons with known extraterrestrial materials (e.g., chondrites). Previous work on IDPs shows a wide range of densities from very low (0.08 g/cm3 [1]) through low (0.3 g/cm3 [2]) to high (6.2 g/cm3 [3]), with an average density at 2.0 g/cm3 for 150 particles [2]. In another study, IDPs fall into two distinct density groups with mean values of 0.6 g/cm3 and 1.9g/cm3 [3]. In general, chondritic IDPs with lower density values most likely have appreciable porosity, suggesting they are primitive, uncompacted particles. It is believed that porosities greater than 70% are rare [2]. Sample In this study, porosity measurements were determined for one IDP, Clu17. This chondritic particle is a fragment of a large-sized IDP (L2008#5) known as a cluster particle. The cluster is composed of 53 fragments >5 micrometers in diameter; a detailed description of the cluster is given in [4]. IDP Clu17 has ~12 wt.% C and contains chondritic abundances (within 2xCI) for major elements. This fragment is dominated by fine-grained aggregates, also known as GEMS (glass with embedded metal and sulfide [5]), and contains some olivine, pyroxene, Fe-Ni sulfides, and carbonaceous material. Methods IDP Clu17 was analyzed for light elements quantitatively analysis using scanning electron microscopy and thin-window energy dispersive spectrometry [details of technique in 4]. Following the initial bulk chemical analysis, the particle was embedded in epoxy, thin sectioned using an ultramicrotome, and examined with a JEOL 2000 FX transmission electron microscope. Many of the sections were not complete; individual grains in some sections are lost during microtoming. Photos from nine of the best sections were digitized by scanning at 1200 dpi. The

  1. Quantification of Meso-Scale Porosity From Borehole Wall Images. Example From the ALIANCE Campos Experimental Site, Mallorca, Spain.

    Science.gov (United States)

    Pezard, P.; Gaillot, P.; Maria-Sube, Y.; Gouze, P.; Lotz, G.

    2004-12-01

    The porosity distribution in carbonates from reefal origin is controlled both by primary and diagenetic processes (fracturing, dolomitisation and dissolution). The study and characterisation of porosity in reservoirs therefore requires a multi-scale and multidisciplinary approach. The analysis of mm-scale digital borehole wall images provides a reliable and practical method to identify mesoscale (vuggy to karstic) porosity and/or fracture porosity, and a new method providing a quantitative analysis of such images is presented here. This new method is based on the analysis of borehole acoustic and optical images. These images have been collected from the MC2 corehole that penetrates the Miocene reefal carbonates of the Campos Coastal site (Mallorca, Baleares, Spain). These sites were drilled in the framework of the Advance Logging Investigations of Aquifers iN Coastal Environment (ALIANCE) European Community Program aimed at developing new techniques to investigate salt-water intrusion in coastal regions. This new method (i) is insensitive to potential eccentering bias of the borehole image logging tools, (ii) analyses vugs and background based on the greyscale colour of each digital images and (iii) calculates the percentage of vuggy/fracture porosity and its attributes in terms of pores size, shape and orientation distributions. Experimentation and comparison with classical porosity determinations (triple weight and Mercury (Hg) porosity) on core, image analysis of slabbed-core samples and thin sections showed that a simple greyscale threshold would not realistically differentiate between greyscale contrast of vugs and background. A moving average calculated around the circumference of the borehole and expressed as the background greyscale intensity is identified as a baseline from which to identify a local greyscale threshold for vugs. Once identified, the characterization of the pores intersected by the borehole as a function of depth and azimuth allow (i) to

  2. Establishing Porosity Gradients within Metal-Organic Frameworks Using Partial Postsynthetic Ligand Exchange.

    Science.gov (United States)

    Liu, Chong; Zeng, Chenjie; Luo, Tian-Yi; Merg, Andrea D; Jin, Rongchao; Rosi, Nathaniel L

    2016-09-21

    Crystalline 3-D materials bearing interlinked domains of differential porosity and functionality offer the potential for organizing and shuttling molecular and nanoscale matter to specific locations within 3-D space. Here, we present methods for creating prototype MOF materials that have such structural features. Specifically, the process of pore expansion via ligand exchange was studied for an isoreticular series of mesoporous MOFs based on bMOF-100. It was found that pore expansion occurs incrementally in small steps and that it proceeds gradually in an "outside→in" fashion within individual crystals. The ligand exchange reaction can be terminated prior to complete crystal conversion to yield intermediate product MOFs, denoted bMOF-100/102 and bMOF-102/106, which bear descending porosity gradients from the crystal periphery to the crystal core. As a proof of concept, size-sensitive incorporation of a gold-thiolate nanocluster, Au133(SR)52, selectively in the bMOF-102/106 crystal periphery region was accomplished via cation exchange. These new methods open up the possibility of controlling molecular organization and transport within porous MOF materials.

  3. Carbon composition with hierarchical porosity, and methods of preparation

    Science.gov (United States)

    Mayes, Richard T; Dai, Sheng

    2014-10-21

    A method for fabricating a porous carbon material possessing a hierarchical porosity, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic component, (iii) a dione component in which carbonyl groups are adjacent, and (iv) an acidic component, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a carbon material possessing a hierarchical porosity comprised of mesopores and macropores. Also described are the resulting hierarchical porous carbon material, a capacitive deionization device in which the porous carbon material is incorporated, as well as methods for desalinating water by use of said capacitive deionization device.

  4. Elastic Equilibrium of Porous Cosserat Media with Double Porosity

    Directory of Open Access Journals (Sweden)

    Roman Janjgava

    2016-01-01

    Full Text Available The static equilibrium of porous elastic materials with double porosity is considered in the case of an elastic Cosserat medium. The corresponding three-dimensional system of differential equations is derived. Detailed consideration is given to the case of plane deformation. A two-dimensional system of equations of plane deformation is written in the complex form and its general solution is represented by means of three analytic functions of a complex variable and two solutions of Helmholtz equations. The constructed general solution enables one to solve analytically a sufficiently wide class of plane boundary value problems of the elastic equilibrium of porous Cosserat media with double porosity. A concrete boundary value problem for a concentric ring is solved.

  5. Prediction of Surface Porosity Defects in High Pressure Die Casting

    Science.gov (United States)

    Saeedipour, Mahdi; Schneiderbauer, Simon; Pirker, Stefan; Bozorgi, Salar

    High pressure die casting (HPDC) is a novel manufacturing method with capability of mass production with higher accuracy. Porosity is one of the challenging defects in final product and may be affected by jet instability and atomization during injection phase. In case of atomization a large number of droplets with high velocity impinges the colder confining walls of the casting mold and might solidify consecutively. Different time scales of the impingement of the droplets and their solidification may result in heterogeneous structures near the surface of final product. A numerical framework using volume of fluid method (VOF) and an Eulerian-Lagrangian approach is established to simulate the liquid metal jet breakup and droplet formation during the injection phase. An analytical model for droplet impact on mold walls and solidification is studied and implemented in the numerical framework. The latter enables the prediction of porosity formation near the surface of final product.

  6. Porosity and Inclusion Detection in CFRP by Infrared Thermography

    Directory of Open Access Journals (Sweden)

    C. Toscano

    2012-01-01

    Full Text Available The ever wide use of composite materials in the aeronautical industry has evidenced the need for development of ever more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production costs. Infrared thermography has been recently enclosed amongst the standardized non destructive testing techniques, but its usefulness needs still complete assessment since it can be employed in several different arrangements and for many purposes. In this work, the possibility to detect slag inclusions and porosity is analyzed with both lock-in themography and pulse thermography in the transmission mode. To this end, carbon-fiber-peinforced polymers different specimens are specifically fabricated of several different stacking sequences and with embedded slag inclusions and porosity percentages. As main results, both of the techniques are found definitely able to reveal the presence of the defects above mentioned. Moreover, these techniques could be considered complementary in order to better characterize the nature of the detected defects.

  7. Using low porosity refractory materials in coke ovens

    Energy Technology Data Exchange (ETDEWEB)

    Narita, Y.; Sudzuki, T.

    1982-02-19

    Refractory bricks with porosity (KP) of less than or equal to 17 percent, which contain less than 1 percent iron oxide and are resiliant at temperatures of more than 1,000/sup 0/C, are made through caking or electrosmelting of materials with a high aluminum content (chamotte, sillimanite, cordierite, pagodite) and silicon content (magnesial chromite, alumina, magnesite, calcite and zircon). In a refractory material with a seeming porosity of less than or equal to 17 percent the deposition of carbon in the pores is reduced which promotes a constant heat conductivity and strength of the refractory material in the operation of coke ovens. Normally the carbon is formed with the reduction of CO under the catalytic action of iron oxide.

  8. Metals Ions Removal by Polymer Membranes of Different Porosity

    Directory of Open Access Journals (Sweden)

    Katarzyna Jasiewicz

    2013-01-01

    Full Text Available The effect of the amount of pore generating agent (polyvinylpyrrolidone added to standard polymer membranes containing 18 wt.% of polyethersulfone on the physicochemical properties of the membranes and their capacity for removal of iron and copper ions from the liquid phase was studied. The membranes were obtained by the phase inversion method. The results have shown that the modification of polymer membranes by the use of different amounts of the pore forming agent in their syntheses leads to significant changes in porosity and has beneficial effect on equilibrium water content. The membranes studied were found to show different acid-base surface character, but for all membranes studied, a significant dominance of oxygen groups of acidic character was evidenced. The most effective were the membranes of the lowest content of polyvinylpyrrolidone, while the lowest values of resistance showed the membranes of the highest content of PVP, and so the ones of the greatest porosity.

  9. Microstructure, porosity and mineralogy around fractures in Olkiluoto bedrock

    Energy Technology Data Exchange (ETDEWEB)

    Kuva, J. (ed.); Myllys, M.; Timonen, J. [Jyvaeskylae Univ. (Finland); Kelokaski, M.; Ikonen, J.; Siitari-Kauppi, M. [Helsinki Univ. (Finland); Lindberg, A. [Geological Survey of Finland, Espoo (Finland); Aaltonen, I.

    2012-01-15

    3D distributions of minerals and porosities were determined for samples that included waterconducting fractures. The analysis of these samples was performed using conventional petrography methods, electron microscopy, C-14-PMMA porosity analysis and X-ray tomography. While X-ray tomography proved to be a very useful method when determining the inner structure of the samples, combining tomography results with those obtained by other methods turned out to be difficult without very careful sample preparation design. It seems that the properties of rock around a water-conducting fracture depend on so many uncorrelated factors that no clear pattern emerged even for rock samples with a given type of fracture. We can conclude, however, that a combination of different analysis methods can be useful and used to infer novel structural information about alteration zones adjacent to fracture surfaces. (orig.)

  10. Porosity Evolution in a Creeping Single Crystal (Preprint)

    Science.gov (United States)

    2012-08-01

    mechanism. Our analyses focus on the role of stress state on deformation and void growth in ductile single crystals in the dislocation creep regime. We also...orientation effects on void growth and coalescence in fcc single crystals . International Journal of Plasticity, 22, 921-942. [27] Kysar J.W., Gan Y.X...AFRL-RX-WP-TP-2012-0373 POROSITY EVOLUTION IN A CREEPING SINGLE CRYSTAL (PREPRINT) A. Srivastava and A. Needleman University of North

  11. Injectable PolyHIPEs as High Porosity Bone Grafts

    Science.gov (United States)

    Moglia, Robert S.; Holm, Jennifer L.; Sears, Nicholas A.; Wilson, Caitlin J.; Harrison, Dawn M.; Cosgriff-Hernandez, Elizabeth

    2011-01-01

    Polymerization of high internal phase emulsions (polyHIPEs) is a relatively new method for the production of high porosity scaffolds. The tunable architecture of these polyHIPE foams make them attractive candidates for tissue engineered bone grafts. Previously studied polyHIPE systems require either toxic diluents or high cure temperatures which prohibit their use as an injectable bone graft. In contrast, we have developed an injectable polyHIPE that cures at physiological temperatures to a rigid, high-porosity foam. First, a biodegradable macromer, propylene fumarate dimethacrylate (PFDMA), was synthesized that has appropriate viscosity and hydrophobicity for emulsification. The process of surfactant selection is detailed with particular focus on the key structural features of both polymer (log P values, hydrogen bond acceptor sites) and surfactant (HLB values, hydrogen bond donor sites) that enable stable HIPE formation. Incubation of HIPEs at 37°C was used to initiate radical crosslinking of the unsaturated double bond of the methacrylate groups to polymerize the continuous phase and lock in the emulsion geometry. The resulting polyHIPEs exhibited ~75% porosity, pore sizes ranging from 4 to 29 μm, and an average compressive modulus and strength of 33 and 5 MPa, respectively. These findings highlight the great potential of these scaffolds as injectable, tissue engineered bone grafts. PMID:21861465

  12. Injectable polyHIPEs as high-porosity bone grafts.

    Science.gov (United States)

    Moglia, Robert S; Holm, Jennifer L; Sears, Nicholas A; Wilson, Caitlin J; Harrison, Dawn M; Cosgriff-Hernandez, Elizabeth

    2011-10-10

    Polymerization of high internal phase emulsions (polyHIPEs) is a relatively new method for the production of high-porosity scaffolds. The tunable architecture of these polyHIPE foams makes them attractive candidates for tissue engineered bone grafts. Previously studied polyHIPE systems require either toxic diluents or high cure temperatures which prohibit their use as an injectable bone graft. In contrast, we have developed an injectable polyHIPE that cures at physiological temperatures to a rigid, high-porosity foam. First, a biodegradable macromer, propylene fumarate dimethacrylate (PFDMA), was synthesized that has appropriate viscosity and hydrophobicity for emulsification. The process of surfactant selection is detailed with particular focus on the key structural features of both polymer (logP values, hydrogen bond acceptor sites) and surfactant (HLB values, hydrogen bond donor sites) that enable stable HIPE formation. Incubation of HIPEs at 37 °C was used to initiate radical cross-linking of the unsaturated double bond of the methacrylate groups to polymerize the continuous phase and lock in the emulsion geometry. The resulting polyHIPEs exhibited ~75% porosity, pore sizes ranging from 4 to 29 μm, and an average compressive modulus and strength of 33 and 5 MPa, respectively. These findings highlight the great potential of these scaffolds as injectable, tissue engineered bone grafts.

  13. The Albedo of Pervious Cement Concrete Linearly Decreases with Porosity

    Directory of Open Access Journals (Sweden)

    Rui Zhang

    2015-01-01

    Full Text Available Pervious pavements have been advocated as a potential countermeasure to the urban heat island effect. To understand if pervious pavements stay cooler than conventional pavements, the albedo of the pervious concrete must be understood. This study measured the albedo of pervious concrete with different porosity. Four Portland cement concrete mixes were casted, using designed amounts of sand to vary the porosity of the pervious concrete samples. The samples were sliced and the spectral reflectance and albedo of the sliced samples were measured and analyzed. It is found that the albedo of pervious concrete decreases linearly with the increase of the porosity. The albedo of a pervious Portland concrete varies from 0.25 to 0.35, which is 0.05~0.15 lower than the albedo of conventional cement concrete. Due to this lower albedo, it should be cautious to develop pervious concrete to battle with urban heat island unless the evaporation of pervious concrete is promoted to compensate the additional solar absorption caused by the low albedo.

  14. Compost addition reduces porosity and chlordecone transfer in soil microstructure.

    Science.gov (United States)

    Woignier, Thierry; Clostre, Florence; Fernandes, Paula; Rangon, Luc; Soler, Alain; Lesueur-Jannoyer, Magalie

    2016-01-01

    Chlordecone, an organochlorine insecticide, pollutes soils and contaminates crops and water resources and is biomagnified by food chains. As chlordecone is partly trapped in the soil, one possible alternative to decontamination may be to increase its containment in the soil, thereby reducing its diffusion into the environment. Containing the pesticide in the soil could be achieved by adding compost because the pollutant has an affinity for organic matter. We hypothesized that adding compost would also change soil porosity, as well as transport and containment of the pesticide. We measured the pore features and studied the nanoscale structure to assess the effect of adding compost on soil microstructure. We simulated changes in the transport properties (hydraulic conductivity and diffusion) associated with changes in porosity. During compost incubation, the clay microstructure collapsed due to capillary stresses. Simulated data showed that the hydraulic conductivity and diffusion coefficient were reduced by 95 and 70% in the clay microstructure, respectively. Reduced transport properties affected pesticide mobility and thus helped reduce its transfer from the soil to water and to the crop. We propose that the containment effect is due not only to the high affinity of chlordecone for soil organic matter but also to a trapping mechanism in the soil porosity.

  15. A functionally gradient variational porosity architecture for hollowed scaffolds fabrication.

    Science.gov (United States)

    Khoda, A K M; Ozbolat, Ibrahim T; Koc, Bahattin

    2011-09-01

    This paper presents a novel continuous tool-path planning methodology for hollowed scaffold fabrication in tissue engineering. A new functionally gradient porous architecture is proposed with a continuous material deposition planning scheme. A controllable variational pore size and hence the porosity have been achieved with a combination of two geometrically oriented consecutive layers. The desired porosity has been achieved with consecutive layers by geometrically partitioning each layer into sub-regions based on the area and the tissue scaffold design constraints. A continuous, interconnected and optimized tool-path for layers has been generated for a three-dimensional biomaterial deposition/printing process. A zigzag pattern tool-path has been proposed for an accumulated sub-region layer, and a concentric spiral-like optimal tool-path pattern has been generated for the successive layer to ensure continuity along the structure. Three-dimensional layers, formed by the proposed tool-path plan, vary the pore size and the porosity based on the biological and mechanical requirements. Several examples demonstrate the proposed methodology along with illustrative results. Also a comparative study between the proposed design and conventional Cartesian coordinate scaffolds has been performed. The results demonstrate a significant reduction in design error with the proposed method. Moreover, sample examples have been fabricated using a micro-nozzle biomaterial deposition system, and characterized for validation.

  16. Porosity Defect Remodeling and Tensile Analysis of Cast Steel

    Directory of Open Access Journals (Sweden)

    Linfeng Sun

    2016-02-01

    Full Text Available Tensile properties on ASTM A216 WCB cast steel with centerline porosity defect were studied with radiographic mapping and finite element remodeling technique. Non-linear elastic and plastic behaviors dependent on porosity were mathematically described by relevant equation sets. According to the ASTM E8 tensile test standard, matrix and defect specimens were machined into two categories by two types of height. After applying radiographic inspection, defect morphologies were mapped to the mid-sections of the finite element models and the porosity fraction fields had been generated with interpolation method. ABAQUS input parameters were confirmed by trial simulations to the matrix specimen and comparison with experimental outcomes. Fine agreements of the result curves between simulations and experiments could be observed, and predicted positions of the tensile fracture were found to be in accordance with the tests. Chord modulus was used to obtain the equivalent elastic stiffness because of the non-linear features. The results showed that elongation was the most influenced term to the defect cast steel, compared with elastic stiffness and yield stress. Additional visual explanations on the tensile fracture caused by void propagation were also given by the result contours at different mechanical stages, including distributions of Mises stress and plastic strain.

  17. A functionally gradient variational porosity architecture for hollowed scaffolds fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Khoda, A K M [Department of Industrial Engineering, University at Buffalo, Buffalo, NY 14260 (United States); Ozbolat, Ibrahim T [Department of Mechanical and Industrial Engineering, Center for Computer Aided Design, University of Iowa, Iowa City, IA 52242-1527 (United States); Koc, Bahattin, E-mail: bahattinkoc@sabanciuniv.edu [Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956 (Turkey)

    2011-09-15

    This paper presents a novel continuous tool-path planning methodology for hollowed scaffold fabrication in tissue engineering. A new functionally gradient porous architecture is proposed with a continuous material deposition planning scheme. A controllable variational pore size and hence the porosity have been achieved with a combination of two geometrically oriented consecutive layers. The desired porosity has been achieved with consecutive layers by geometrically partitioning each layer into sub-regions based on the area and the tissue scaffold design constraints. A continuous, interconnected and optimized tool-path for layers has been generated for a three-dimensional biomaterial deposition/printing process. A zigzag pattern tool-path has been proposed for an accumulated sub-region layer, and a concentric spiral-like optimal tool-path pattern has been generated for the successive layer to ensure continuity along the structure. Three-dimensional layers, formed by the proposed tool-path plan, vary the pore size and the porosity based on the biological and mechanical requirements. Several examples demonstrate the proposed methodology along with illustrative results. Also a comparative study between the proposed design and conventional Cartesian coordinate scaffolds has been performed. The results demonstrate a significant reduction in design error with the proposed method. Moreover, sample examples have been fabricated using a micro-nozzle biomaterial deposition system, and characterized for validation.

  18. THE EFFECT OF POROSITY ON THE STRUCTURE AND PROPERTIES OF CALCIUM POLYPHOSPHATE BIOCERAMICS

    Directory of Open Access Journals (Sweden)

    CHANGXIU WAN

    2011-03-01

    Full Text Available Calcium polyphosphate (CPP bioceramic with different porosities were prepared by controlling the concentration of the pore-foaming agent. Effect of porosity (0%, 15%, 30%, 45% and 60% on the microstructure, pores interconnection, dissolution behavior and compressive strength of CPP bioceramic were investigated. Scanning electron microscope (SEM and capillarity test results indicated that CPP with higher porosity (45% and 60% exhibited three-dimensional interconnected pore structure with a pore size of about 200–400 μm, while the pores of lower porosity scaffold (0%, 15% and 30% were isolated. The dissolution behavior in vitro indicated that the dissolution rate accelerated with the porosity increasing and the CPP with 60% porosity showed the highest dissolution velocity. The compressive strength of porosity CPP scaffolds were as much as the human cancellous bone, which decreased with the increase of porosity. While the dense CPP scaffolds lie in the same order of magnitude as compact bone.

  19. Diametral compression behavior of biomedical titanium scaffolds with open, interconnected pores prepared with the space holder method.

    Science.gov (United States)

    Arifvianto, B; Leeflang, M A; Zhou, J

    2017-04-01

    Scaffolds with open, interconnected pores and appropriate mechanical properties are required to provide mechanical support and to guide the formation and development of new tissue in bone tissue engineering. Since the mechanical properties of the scaffold tend to decrease with increasing porosity, a balance must be sought in order to meet these two conflicting requirements. In this research, open, interconnected pores and mechanical properties of biomedical titanium scaffolds prepared by using the space holder method were characterized. Micro-computed tomography (micro-CT) and permeability analysis were carried out to quantify the porous structures and ascertain the presence of open, interconnected pores in the scaffolds fabricated. Diametral compression (DC) tests were performed to generate stress-strain diagrams that could be used to determine the elastic moduli and yield strengths of the scaffolds. Deformation and failure mechanisms involved in the DC tests of the titanium scaffolds were examined. The results of micro-CT and permeability analyses confirmed the presence of open, interconnected pores in the titanium scaffolds with porosity over a range of 31-61%. Among these scaffolds, a maximum specific surface area could be achieved in the scaffold with a total porosity of 5-55%. DC tests showed that the titanium scaffolds with elastic moduli and yield strengths of 0.64-3.47GPa and 28.67-80MPa, respectively, could be achieved. By comprehensive consideration of specific surface area, permeability and mechanical properties, the titanium scaffolds with porosities in a range of 50-55% were recommended to be used in cancellous bone tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Tailoring of porosity of yttria-stabilized zirconia tubes as supports for oxygen separation membranes

    DEFF Research Database (Denmark)

    Bjørnetun Haugen, Astri; Kothanda Ramachandran, Dhavanesan; Gurauskis, Jonas

    straightforward sealing. The active oxygen separation layer in the membrane should be as thin as possible and therefore supported on a highly porous tubular substrate. In this work tubular porous supports of yttria-stabilized zirconia have been manufactured using thermoplastic extrusion. Two types of poreformers...... deformation during debinding. The influence of the amount of pore formers (relative to the amount of ceramic and thermoplastics) on the microstructure of sintered samples, as well as the extrudability and ease of debinding of the feedstock, has been studied. Ceramics with 1-20 μm pores, open porosities...... exceeding 55 % and gas permeabilities close to 10-14 m2 could be produced, demonstrating that thermoplastic extrusion is suitable for fabrication of porous and permeable tubes....

  1. Improved dual-porosity models for petrophysical analysis of vuggy reservoirs

    Science.gov (United States)

    Wang, Haitao

    2017-08-01

    A new vug interconnection, isolated vug (IVG), was investigated through resistivity modeling and the dual-porosity model for connected vug (CVG) vuggy reservoirs was tested. The vuggy models were built by pore-scale modeling, and their electrical resistivity was calculated by the finite difference method. For CVG vuggy reservoirs, the CVG reduced formation factors and increased the porosity exponents, and the existing dual-porosity model failed to match these results. Based on the existing dual-porosity model, a conceptual dual-porosity model for CVG was developed by introducing a decoupled term to reduce the resistivity of the model. For IVG vuggy reservoirs, IVG increased the formation factors and porosity exponents. The existing dual-porosity model succeeded due to accurate calculation of the formation factors of the deformed interparticle porous media caused by the insertion of the IVG. Based on the existing dual-porosity model, a new porosity model for IVG vuggy reservoirs was developed by simultaneously recalculating the formation factors of the altered interparticle pore-scale models. The formation factors and porosity exponents from the improved and extended dual-porosity models for CVG and IVG vuggy reservoirs well matched the simulated formation factors and porosity exponents. This work is helpful for understanding the influence of connected and disconnected vugs on resistivity factors—an issue of particular importance in carbonates.

  2. Relationships between permeability, porosity and pore throat size in carbonate rocks using regression analysis and neural networks

    Science.gov (United States)

    Rezaee, M. R.; Jafari, A.; Kazemzadeh, E.

    2006-12-01

    Accurate estimation of permeability from other data has been a challenge for many years. The aim of this study was to establish relationships between permeability, porosity and pore throat size, and apply these relationships in a predictive sense. Regression analysis was utilized to achieve a set of relationships between permeability, porosity and pore throat size for 144 carbonate samples. These relationships can be used to estimate permeability from porosity and pore throat radii. Also in this study, a fully-connected multi-layer perceptron network was used to predict permeability from porosity and pore throat radii. An artificial neural network, a biologically inspired computing method which has an ability to learn, self-adjust, and be trained, provides a powerful tool in solving complex problems. These characteristics have enabled artificial neural networks to be more successful in predicting permeability when compared to regression analysis. This study also indicates that pore throat radii corresponding to a mercury saturation of 50% (r50) is the best permeability predictor for carbonates with complex pore networks.

  3. Adobe photoshop quantification (PSQ) rather than point-counting: A rapid and precise method for quantifying rock textural data and porosities

    Science.gov (United States)

    Zhang, Xuefeng; Liu, Bo; Wang, Jieqiong; Zhang, Zhe; Shi, Kaibo; Wu, Shuanglin

    2014-08-01

    Commonly used petrological quantification methods are visual estimation, counting, and image analyses. However, in this article, an Adobe Photoshop-based analyzing method (PSQ) is recommended for quantifying the rock textural data and porosities. Adobe Photoshop system provides versatile abilities in selecting an area of interest and the pixel number of a selection could be read and used to calculate its area percentage. Therefore, Adobe Photoshop could be used to rapidly quantify textural components, such as content of grains, cements, and porosities including total porosities and different genetic type porosities. This method was named as Adobe Photoshop Quantification (PSQ). The workflow of the PSQ method was introduced with the oolitic dolomite samples from the Triassic Feixianguan Formation, Northeastern Sichuan Basin, China, for example. And the method was tested by comparing with the Folk's and Shvetsov's "standard" diagrams. In both cases, there is a close agreement between the "standard" percentages and those determined by the PSQ method with really small counting errors and operator errors, small standard deviations and high confidence levels. The porosities quantified by PSQ were evaluated against those determined by the whole rock helium gas expansion method to test the specimen errors. Results have shown that the porosities quantified by the PSQ are well correlated to the porosities determined by the conventional helium gas expansion method. Generally small discrepancies (mostly ranging from -3% to 3%) are caused by microporosities which would cause systematic underestimation of 2% and/or by macroporosities causing underestimation or overestimation in different cases. Adobe Photoshop could be used to quantify rock textural components and porosities. This method has been tested to be precise and accurate. It is time saving compared with usual methods.

  4. Impact of silica diagenesis on the porosity of fine-grained strata: An analysis of Cenozoic mudstones from the North Sea

    Science.gov (United States)

    Wrona, Thilo; Taylor, Kevin G.; Jackson, Christopher A.-L.; Huuse, Mads; Najorka, Jens; Pan, Indranil

    2017-04-01

    Silica diagenesis has the potential to drastically change the physical and fluid flow properties of its host strata and therefore plays a key role in the development of sedimentary basins. The specific processes involved in silica diagenesis are, however, still poorly explained by existing models. This knowledge gap is addressed by investigating the effect of silica diagenesis on the porosity of Cenozoic mudstones of the North Viking Graben, northern North Sea through a multiple linear regression analysis. First, we identify and quantify the mineralogy of these rocks by scanning electron microscopy and X-ray diffraction, respectively. Mineral contents and host rock porosity data inferred from wireline data of two exploration wells are then analyzed by multiple linear regressions. This robust statistical analysis reveals that biogenic opal-A is a significant control and authigenic opal-CT is a minor influence on the porosity of these rocks. These results suggest that the initial porosity of siliceous mudstones increases with biogenic opal-A production during deposition and that the porosity reduction during opal-A/CT transformation results from opal-A dissolution. These findings advance our understanding of compaction, dewatering, and lithification of siliceous sediments and rocks. Moreover, this study provides a recipe for the derivation of the key controls (e.g., composition) on a rock property (e.g., porosity) that can be applied to a variety of problems in rock physics.

  5. Examining the Social Porosity of Environmental Features on Neighborhood Sociability and Attachment

    Science.gov (United States)

    Hipp, John R.; Corcoran, Jonathan; Wickes, Rebecca; Li, Tiebei

    2014-01-01

    The local neighborhood forms an integral part of our lives. It provides the context through which social networks are nurtured and the foundation from which a sense of attachment and cohesion with fellow residents can be established. Whereas much of the previous research has examined the role of social and demographic characteristic in relation to the level of neighboring and cohesion, this paper explores whether particular environmental features in the neighborhood affect social porosity. We define social porosity as the degree to which social ties flow over the surface of a neighborhood. The focus of our paper is to examine the extent to which a neighborhood's environmental features impede the level of social porosity present among residents. To do this, we integrate data from the census, topographic databases and a 2010 survey of 4,351 residents from 146 neighborhoods in Australia. The study introduces the concepts of wedges and social holes. The presence of two sources of wedges is measured: rivers and highways. The presence of two sources of social holes is measured: parks and industrial areas. Borrowing from the geography literature, several measures are constructed to capture how these features collectively carve up the physical environment of neighborhoods. We then consider how this influences residents' neighboring behavior, their level of attachment to the neighborhood and their sense of neighborhood cohesion. We find that the distance of a neighborhood to one form of social hole–industrial areas–has a particularly strong negative effect on all three dependent variables. The presence of the other form of social hole–parks–has a weaker negative effect. Neighborhood wedges also impact social interaction. Both the length of a river and the number of highway fragments in a neighborhood has a consistent negative effect on neighboring, attachment and cohesion. PMID:24427288

  6. Examining the social porosity of environmental features on neighborhood sociability and attachment.

    Directory of Open Access Journals (Sweden)

    John R Hipp

    Full Text Available The local neighborhood forms an integral part of our lives. It provides the context through which social networks are nurtured and the foundation from which a sense of attachment and cohesion with fellow residents can be established. Whereas much of the previous research has examined the role of social and demographic characteristic in relation to the level of neighboring and cohesion, this paper explores whether particular environmental features in the neighborhood affect social porosity. We define social porosity as the degree to which social ties flow over the surface of a neighborhood. The focus of our paper is to examine the extent to which a neighborhood's environmental features impede the level of social porosity present among residents. To do this, we integrate data from the census, topographic databases and a 2010 survey of 4,351 residents from 146 neighborhoods in Australia. The study introduces the concepts of wedges and social holes. The presence of two sources of wedges is measured: rivers and highways. The presence of two sources of social holes is measured: parks and industrial areas. Borrowing from the geography literature, several measures are constructed to capture how these features collectively carve up the physical environment of neighborhoods. We then consider how this influences residents' neighboring behavior, their level of attachment to the neighborhood and their sense of neighborhood cohesion. We find that the distance of a neighborhood to one form of social hole-industrial areas-has a particularly strong negative effect on all three dependent variables. The presence of the other form of social hole-parks-has a weaker negative effect. Neighborhood wedges also impact social interaction. Both the length of a river and the number of highway fragments in a neighborhood has a consistent negative effect on neighboring, attachment and cohesion.

  7. Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering.

    Science.gov (United States)

    Vikingsson, L; Claessens, B; Gómez-Tejedor, J A; Gallego Ferrer, G; Gómez Ribelles, J L

    2015-08-01

    In tissue engineering the design and optimization of biodegradable polymeric scaffolds with a 3D-structure is an important field. The porous scaffold provide the cells with an adequate biomechanical environment that allows mechanotransduction signals for cell differentiation and the scaffolds also protect the cells from initial compressive loading. The scaffold have interconnected macro-pores that host the cells and newly formed tissue, while the pore walls should be micro-porous to transport nutrients and waste products. Polycaprolactone (PCL) scaffolds with a double micro- and macro-pore architecture have been proposed for cartilage regeneration. This work explores the influence of the micro-porosity of the pore walls on water permeability and scaffold compliance. A Poly(Vinyl Alcohol) with tailored mechanical properties has been used to simulate the growing cartilage tissue inside the scaffold pores. Unconfined and confined compression tests were performed to characterize both the water permeability and the mechanical response of scaffolds with varying size of micro-porosity while volume fraction of the macro-pores remains constant. The stress relaxation tests show that the stress response of the scaffold/hydrogel construct is a synergic effect determined by the performance of the both components. This is interesting since it suggests that the in vivo outcome of the scaffold is not only dependent upon the material architecture but also the growing tissue inside the scaffold׳s pores. On the other hand, confined compression results show that compliance of the scaffold is mainly controlled by the micro-porosity of the scaffold and less by hydrogel density in the scaffold pores. These conclusions bring together valuable information for customizing the optimal scaffold and to predict the in vivo mechanical behavior. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Effect of Porosity Content of Arc-Sprayed Alloy 625 Skins on the Flexural Behavior of Nickel Foam Core Sandwich Structures

    Science.gov (United States)

    Salavati, S.; Pershin, L.; Coyle, T. W.; Mostaghimi, J.

    2015-01-01

    Metallic foam core sandwich structures have been of particular interest for engineering applications in recent decades because of their unique mechanical and physical properties. Thermal spraying techniques have been recently introduced as a novel low-cost method for production of these structures with complex shapes. One of the potential applications of the metallic foam core sandwich structures prepared by thermal spray techniques is as heat shield devices. Open porosity in the microstructure of the coating may allow the cooling efficiency of the heat shield to be improved through the film cooling phenomenon. A modified twin wire-arc spraying process was employed to deposit high temperature resistant alloy 625 coatings with a high percentage of the open porosity. The effect of skin porosity on the mechanical properties (flexural rigidity) of the sandwich structures was studied using a four-point bending test. It was concluded from the four-point bending test results that increase in the porosity content of the coatings leads to decrease in the flexural rigidity of the sandwich panels. The ductility of the porous and conventional arc-sprayed alloy 625 coatings was improved after heat treatment at 1100 °C for 3 h.

  9. Effect of shelter porosity on downwind flow characteristics

    Science.gov (United States)

    Nosek, Š.; Kellnerová, R.; Jurčáková, K.; Jaňour, Z.; Chaloupecká, H.; Jakubcová, M.

    2016-03-01

    Previous wind-tunnel studies were focused mainly on lonely standing windbreaks or wind fences with respect to their wind velocity reduction efficiency and effective shelter distance. In presented wind-tunnel study, we investigated the effects of a three different fence porosities (0.5, 0.25 and 0) embodied in a shelter-like building for coal convey by means of two-component Laser Doppler Anemometry (LDA). The turbulent flow characteristics behind the fences were compared with those performed without the fence. For characterization of the fence effectiveness we used following quantities: wind-speed and turbulence kinetic energy reduction, and time fractions of the turbulent coherent structures associated with the sediment transport (sweeps and outward interactions). Results from mentioned quantities revealed that for the case of embodied fence the shelter construction has significant impact on the flow characteristics behind. The fence of the 0.5 porosity has been indicated as the most shelter effective considering the studied quantities.

  10. Increased Cortical Porosity in Type-2 Diabetic Postmenopausal Women with Fragility Fractures

    Science.gov (United States)

    Patsch, Janina M.; Burghardt, Andrew J.; Yap, Samuel P.; Baum, Thomas; Schwartz, Ann V.; Joseph, Gabby B.; Link, Thomas M.

    2012-01-01

    The primary goal of this study was to assess peripheral bone microarchitecture and strength in diabetic postmenopausal women with fragility fractures (DMFx) and to compare them with diabetic women without fracture (DM). Secondary goals were to assess differences in non-diabetic women with (Fx) and without fragility fractures (Co) and in women with (DM) and without diabetes (Co). Eighty women (mean age 61.3±5.7 yrs) were recruited into these groups (n=20 per group). Participants underwent DXA and high-resolution peripheral quantitative computed tomography (HR-pQCT) of the ultradistal and distal radius and tibia. In the HR-pQCT images volumetric bone mineral density, cortical and trabecular structure measures, including cortical porosity, were calculated. Bone strength was estimated using micro-finite element analysis (μFEA). Differential strength estimates were obtained with and without open cortical pores. At the ultradistal and distal tibia, DMFx had greater intracortical pore volume (+52.6%, p=0.009; +95.4%, p=0.020), relative porosity (+58.1%; p=0.005; +87.9%, p=0.011) and endocortical bone surface (+10.9%, p=0.031; +11.5%, 0.019) than DM. At the distal radius DMFx had 4.7-fold greater relative porosity (p=0.000) than DM. At the ultradistal radius, intracortical pore volume was significantly higher in DMFx than DM (+67.8%, p=0.018). DMFx also displayed larger trabecular heterogeneity (ultradistal radius; +36.8%, p=0.035), and lower total and cortical BMD (ultradistal tibia: −12.6%, p=0.031; −6.8%, p=0.011) than DM. DMFx exhibited significantly higher pore-related deficits in stiffness, failure load and cortical load fraction at the ultradistal and distal tibia, and the distal radius than DM. Comparing non-diabetic Fx and Co, we only found a non-significant trend with increase in pore volume (+38.9%, p=0.060) at the ultradistal radius. The results of our study suggest that severe deficits in cortical bone quality are responsible for fragility fractures in

  11. Opening education.

    Science.gov (United States)

    Smith, Marshall S

    2009-01-02

    Spurred by the publication of Massachusetts Institute of Technology OpenCourseWare in 2002, the open educational resources (OER) movement, which has rapidly expanded and captured the imagination and energy of millions of creators and users throughout the world, now faces many opportunities and substantial challenges as it moves to become an integral part of the world's educational environment. The confluence of the Web and a spirit of sharing intellectual property have fueled a worldwide movement to make knowledge and education materials open to all for use. OER are content (courses, books, lesson plans, articles, etc.), tools (virtual laboratories, simulations, and games), and software that support learning and educational practice. OER are free on the Web, and most have licenses that allow copyright holders to retain ownership while providing specified rights for use in original and modified forms. At the least, OER have helped to level the distribution of knowledge across the world. A second promise of OER is to help transform educational practices. This article explores the history of and promises and challenges for OER.

  12. Providing affinity

    DEFF Research Database (Denmark)

    Guglielmi, Michel; Johannesen, Hl

    2004-01-01

    This paper will introduce a project sourced by an ideas competition called Landmark East England. It was open to anyone with the ability to develop and deliver a visionary idea for a landmark. A sustainable icon representing a new region in England, which comprises Bedfordshire, Cambridgeshire, E...

  13. A comparison of estimated and calculated effective porosity

    Science.gov (United States)

    Stephens, Daniel B.; Hsu, Kuo-Chin; Prieksat, Mark A.; Ankeny, Mark D.; Blandford, Neil; Roth, Tracy L.; Kelsey, James A.; Whitworth, Julia R.

    Effective porosity in solute-transport analyses is usually estimated rather than calculated from tracer tests in the field or laboratory. Calculated values of effective porosity in the laboratory on three different textured samples were compared to estimates derived from particle-size distributions and soil-water characteristic curves. The agreement was poor and it seems that no clear relationships exist between effective porosity calculated from laboratory tracer tests and effective porosity estimated from particle-size distributions and soil-water characteristic curves. A field tracer test in a sand-and-gravel aquifer produced a calculated effective porosity of approximately 0.17. By comparison, estimates of effective porosity from textural data, moisture retention, and published values were approximately 50-90% greater than the field calibrated value. Thus, estimation of effective porosity for chemical transport is highly dependent on the chosen transport model and is best obtained by laboratory or field tracer tests. Résumé La porosité effective dans les analyses de transport de soluté est habituellement estimée, plutôt que calculée à partir d'expériences de traçage sur le terrain ou au laboratoire. Les valeurs calculées de la porosité effective au laboratoire sur trois échantillons de textures différentes ont été comparées aux estimations provenant de distributions de taille de particules et de courbes caractéristiques sol-eau. La concordance était plutôt faible et il semble qu'il n'existe aucune relation claire entre la porosité effective calculée à partir des expériences de traçage au laboratoire et la porosité effective estimée à partir des distributions de taille de particules et de courbes caractéristiques sol-eau. Une expérience de traçage de terrain dans un aquifère de sables et de graviers a fourni une porosité effective calculée d'environ 0,17. En comparaison, les estimations de porosité effective de données de

  14. An Efficient Modelling Approach for Prediction of Porosity Severity in Composite Structures

    Science.gov (United States)

    Bedayat, Houman; Forghani, Alireza; Hickmott, Curtis; Roy, Martin; Palmieri, Frank; Grimsley, Brian; Coxon, Brian; Fernlund, Goran

    2017-01-01

    Porosity, as a manufacturing process-induced defect, highly affects the mechanical properties of cured composites. Multiple phenomena affect the formation of porosity during the cure process. Porosity sources include entrapped air, volatiles and off-gassing as well as bag and tool leaks. Porosity sinks are the mechanisms that contribute to reducing porosity, including gas transport, void shrinkage and collapse as well as resin flow into void space. Despite the significant progress in porosity research, the fundamentals of porosity in composites are not yet fully understood. The highly coupled multi-physics and multi-scale nature of porosity make it a complicated problem to predict. Experimental evidence shows that resin pressure history throughout the cure cycle plays an important role in the porosity of the cured part. Maintaining high resin pressure results in void shrinkage and collapse keeps volatiles in solution thus preventing off-gassing and bubble formation. This study summarizes the latest development of an efficient FE modeling framework to simulate the gas and resin transport mechanisms that are among the major phenomena contributing to porosity.

  15. Open Hardware Business Models

    Directory of Open Access Journals (Sweden)

    Edy Ferreira

    2008-04-01

    Full Text Available In the September issue of the Open Source Business Resource, Patrick McNamara, president of the Open Hardware Foundation, gave a comprehensive introduction to the concept of open hardware, including some insights about the potential benefits for both companies and users. In this article, we present the topic from a different perspective, providing a classification of market offers from companies that are making money with open hardware.

  16. OpenGrey

    OpenAIRE

    Pejšová, Petra; Stock, Christiane

    2012-01-01

    OpenGrey is a unique repository providing open access to European grey literature references, the result of 25 years of cooperation. OpenGrey is based on the OpenSIGLE/SIGLE database which contains almost 700 thousand records of grey literature. As a multidisciplinary database it covers Science, Technology, Biomedical Science, Economics, Social Science and Humanities. This paper presents new search functionality, design, logo and vision. The cooperation with GreyNet on GL conference preprints...

  17. Insights into the dolomitization process and porosity modification in sucrosic dolostones, Avon Park Formation (Middle Eocene), East-Central Florida, U.S.A.

    KAUST Repository

    Maliva,, Robert G.

    2011-03-01

    The Avon Park Formation (middle Eocene) in central Florida, U.S.A., contains shallow-water carbonates that have been replaced by dolomite to varying degrees, ranging from partially replaced limestones, to highly porous sucrosic dolostones, to, less commonly, low-porosity dense dolostones. The relationships between dolomitization and porosity and permeability were studied focusing on three 305-m-long cores taken in the City of Daytona Beach. Stable-isotope data from pure dolostones (mean δ 18O = +3.91% V-PDB) indicate dolomite precipitation in Eocene penesaline pore waters, which would be expected to have been at or above saturation with respect to calcite. Nuclear magnetic log-derived porosity and permeability data indicate that dolomitization did not materially change total porosity values at the bed and formation scale, but did result in a general increase in pore size and an associated substantial increase in permeability compared to limestone precursors. Dolomitization differentially affects the porosity and permeability of carbonate strata on the scale of individual crystals, beds, and formations. At the crystal scale, dolomitization occurs in a volume-for-volume manner in which the space occupied by the former porous calcium carbonate is replaced by a solid dolomite crystal with an associated reduction in porosity. Dolomite crystal precipitation was principally responsible for calcite dissolution both at the actual site of dolomite crystal growth and in the adjoining rock mass. Carbonate is passively scavenged from the formation, which results in no significant porosity change at the formation scale. Moldic pores after allochems formed mainly in beds that experienced high degrees of dolomitization, which demonstrates the intimate association of the dolomitization process with carbonate dissolution. The model of force of crystallization-controlled replacement provides a plausible explanation for key observations concerning the dolomitization process in the

  18. Spark plasma sintering and porosity studies of uranium nitride

    Science.gov (United States)

    Johnson, Kyle D.; Wallenius, Janne; Jolkkonen, Mikael; Claisse, Antoine

    2016-05-01

    In this study, a number of samples of UN sintered by the SPS method have been fabricated, and highly pure samples ranging in density from 68% to 99.8%TD - corresponding to an absolute density of 14.25 g/cm3 out of a theoretical density of 14.28 g/cm3 - have been fabricated. By careful adjustment of the sintering parameters of temperature and applied pressure, the production of pellets of specific porosity may now be achieved between these ranges. The pore closure behaviour of the material has also been documented and compared to previous studies of similar materials, which demonstrates that full pore closure using these methods occurs near 97.5% of relative density.

  19. Monolithic SiOC ceramics with tailored porosity

    Energy Technology Data Exchange (ETDEWEB)

    Berndt, F.; Jahn, P.; Motz, G.; Ziegler, G. [Bayreuth Univ. (Germany). Inst. for Materials Research; Rendtel, A. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2002-07-01

    Mixing two catalytically cross-linking liquid polysiloxanes leads to porous but crack-free bodies after pyrolysis at 1100 C in nitrogen. The low viscosity of the polysiloxanes allows the application of polymer-based moulding techniques like casting of complex-shaped SiOC components. Porosity and pore formation can be varied by changing the mixing ratio of the polysiloxanes. Pore formation affects strength, elastic modulus, fracture toughness, and creep behaviour. Four point bending strength varies between about 125 and 150 MPa (specimen size 3.5 x 3.0 x 50 mm{sup 3}). Analysis of fracture surfaces shows crack deflection at the pores leading to fracture toughness values of up to 2.0 MPa m{sup 1/2}. Investigation of the creep behaviour in compression revealed an improved creep resistance compared to silica glass depending on the thermal history of the amorphous material. (orig.)

  20. Controlling porosity in bridged polysilsesquioxanes through elimination reactions

    Energy Technology Data Exchange (ETDEWEB)

    McClain, M.D.; Loy, D.A. [Sandia National Labs., Albuquerque, NM (United States); Prabakar, S. [Univ. of New Mexico, Albuquerque, NM (United States). Advanced Materials Lab.

    1996-06-01

    The retro Diels-Alder reaction was used to modify porosity in hydrocarbon-bridged polysilsesquioxane gels. Microporous polysilsesquioxanes incorporating a thermally labile Diels-Alder adduct as the hydrocarbon bridging group were prepared by sol-gel polymerization of trans-2,3-bis(triethoxysilyl)norbornene. Upon heating the 2,3-norbornenylene-bridges polymers at temperatures above 250 C, the norbornenylene-bridging group underwent a retro Diels-Alder reaction losing cyclopentadiene and leaving behind a ethenylene-bridged polysilsesquioxane. Less than theoretical quantities of cyclopentadiene were volatilized indicating that some of the diene was either reacting with the silanol and olefinic rich material or undergoing oligomerization. Both scanning electron microscopy and nitrogen sorption porosimetry revealed net coarsening of pores (and reduction of surface area) in the materials with thermolysis.

  1. Modeling Flow in Porous Media with Double Porosity/Permeability.

    Science.gov (United States)

    Seyed Joodat, S. H.; Nakshatrala, K. B.; Ballarini, R.

    2016-12-01

    Although several continuum models are available to study the flow of fluids in porous media with two pore-networks [1], they lack a firm theoretical basis. In this poster presentation, we will present a mathematical model with firm thermodynamic basis and a robust computational framework for studying flow in porous media that exhibit double porosity/permeability. The mathematical model will be derived by appealing to the maximization of rate of dissipation hypothesis, which ensures that the model is in accord with the second law of thermodynamics. We will also present important properties that the solutions under the model satisfy, along with an analytical solution procedure based on the Green's function method. On the computational front, a stabilized mixed finite element formulation will be derived based on the variational multi-scale formalism. The equal-order interpolation, which is computationally the most convenient, is stable under this formulation. The performance of this formulation will be demonstrated using patch tests, numerical convergence study, and representative problems. It will be shown that the pressure and velocity profiles under the double porosity/permeability model are qualitatively and quantitatively different from the corresponding ones under the classical Darcy equations. Finally, it will be illustrated that the surface pore-structure is not sufficient in characterizing the flow through a complex porous medium, which pitches a case for using advanced characterization tools like micro-CT. References [1] G. I. Barenblatt, I. P. Zheltov, and I. N. Kochina, "Basic concepts in the theory of seepage of homogeneous liquids in fissured rocks [strata]," Journal of Applied Mathematics and Mechanics, vol. 24, pp. 1286-1303, 1960.

  2. Correlation between triple phase boundary and the microstructure of Solid Oxide Fuel Cell anodes: The role of composition, porosity and Ni densification

    Science.gov (United States)

    Lu, Xuekun; Heenan, Thomas M. M.; Bailey, Josh J.; Li, Tao; Li, Kang; Brett, Daniel J. L.; Shearing, Paul R.

    2017-10-01

    This study aims to correlate the active triple phase boundaries (TPBs) to the variation of as-prepared anode microstructures and Ni densifications based on the reconstructed 3D volume of an SOFC anode, providing a point of comparison with theoretical studies that reveal the relationship of TPBs and the material microstructure using randomly packed spheres models. The TPB degradation mechanisms are explained using a particle network model. The results indicate that in low porosity regime, the TPBs sharply increase with the porosity until the percolation threshold (10%); at intermediate porosity (10%-25%), a balance of surface area between three phases is more critical than that of volume fraction to reach the optimal TPB density; in the high porosity regime (>25%), the TPBs start to drop due to the shrinkage and detachment of Ni/YSZ interfaces. The TPB density is inversely proportional to the degree of Ni densification as long as the Ni content is above the percolation threshold (35%) and can be improved by 70% within 7% change of porosity provided that the over-densification is mitigated. This has implications for the design of SOFC microstructures as well for electrode durability, where Ni agglomeration is known to deleteriously impact long-term operation.

  3. Matrix diffusion coefficients in volcanic rocks at the Nevada test site: Influence of matrix porosity, matrix permeability, and fracture coating minerals

    Science.gov (United States)

    Reimus, Paul W.; Callahan, Timothy J.; Ware, S. Doug; Haga, Marc J.; Counce, Dale A.

    2007-08-01

    Diffusion cell experiments were conducted to measure nonsorbing solute matrix diffusion coefficients in forty-seven different volcanic rock matrix samples from eight different locations (with multiple depth intervals represented at several locations) at the Nevada Test Site. The solutes used in the experiments included bromide, iodide, pentafluorobenzoate (PFBA), and tritiated water ( 3HHO). The porosity and saturated permeability of most of the diffusion cell samples were measured to evaluate the correlation of these two variables with tracer matrix diffusion coefficients divided by the free-water diffusion coefficient ( Dm/ D*). To investigate the influence of fracture coating minerals on matrix diffusion, ten of the diffusion cells represented paired samples from the same depth interval in which one sample contained a fracture surface with mineral coatings and the other sample consisted of only pure matrix. The log of ( Dm/ D*) was found to be positively correlated with both the matrix porosity and the log of matrix permeability. A multiple linear regression analysis indicated that both parameters contributed significantly to the regression at the 95% confidence level. However, the log of the matrix diffusion coefficient was more highly-correlated with the log of matrix permeability than with matrix porosity, which suggests that matrix diffusion coefficients, like matrix permeabilities, have a greater dependence on the interconnectedness of matrix porosity than on the matrix porosity itself. The regression equation for the volcanic rocks was found to provide satisfactory predictions of log( Dm/ D*) for other types of rocks with similar ranges of matrix porosity and permeability as the volcanic rocks, but it did a poorer job predicting log( Dm/ D*) for rocks with lower porosities and/or permeabilities. The presence of mineral coatings on fracture walls did not appear to have a significant effect on matrix diffusion in the ten paired diffusion cell experiments.

  4. Effective porosity and density of carbonate rocks (Maynardville Limestone and Copper Ridge Dolomite) within Bear Creek Valley on the Oak Ridge Reservation based on modern petrophysical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Dorsch, J.

    1997-02-01

    The purpose of this study is to provide quantitative data on effective porosity of carbonate rock from the Maynardville Limestone and Copper Ridge Dolomite within Bear Creek Valley based on modern petrophysical techniques. The data will be useful for groundwater-flow and contaminant-flow modeling in the vicinity of the Y-12 Plant on the Oak Ridge Reservation (ORR). Furthermore, the data provides needed information on the amount of interconnected pore space potentially available for operation of matrix diffusion as a transport process within the fractured carbonate rock. A second aspect of this study is to compare effective porosity data based on modern petrophysical techniques to effective porosity data determined earlier by Goldstrand et al. (1995) with a different technique. An added bonus of the study is quantitative data on the bulk density and grain density of dolostone and limestone of the Maynardville Limestone and Copper Ridge Dolomite which might find use for geophysical modeling on the ORR.

  5. The usage of velocity deviation log (VDL) in order to recognize porosity types and trends in permeability of the Asmari and Jahrum reservoirs units in the KHESHT oil field (Kazeroon)

    Science.gov (United States)

    Morshedi Pour, Amin; Lotfpour, Masoud; Enayati, Aliasghar

    2010-05-01

    Porosity value is one of the most important factors which determine the oil volume and also basis of economical or uneconomical calculation of a distinct oil field. By combining the logs, nowadays, very detailed and precise issues could be recognized, for instance we could point examining of porosity types and trends in permeability by using the velocity deviation log (VDL). Velocity devotion log which is calculated by combination sonic log with the Norton porosity or density log provides tool to obtain down hole information on the predominate pore type in carbonates the log can be use to trace the down hole distribution of digenetic processes and to estimate trends in permeability. Generally speaking, porosity and velocity have inverted relationship; nevertheless the type of porosity changes this relationship. In order to establish the velocity deviation log at first; by using the Wyllie equation, porosity log was exchanged to synthetic velocity log, acquired real velocity difference from sonic log and the acquired synthetic velocity from the porosity log is expressed as velocity deviation log. With log being deviated to left and right, the type of porosity would be identified .this method is applied for the Asmari and Jahrum reservoirs units of the Khesht oil field in Kazeroon (Fars),And in one of the wells. This log approves the boundary of Formations which is along with unconformities and even zoning whether is based on porosity value or change of lithology, and also the results which are gotten from the log have close similarities with the results of thin section studies in terms of porosity. Drawing of log and calculation of petrophysic parameters are done by Geolog software.

  6. Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

    Directory of Open Access Journals (Sweden)

    Sebastian Spath

    2015-07-01

    Full Text Available 3D printing is a promising method for the fabrication of scaffolds in the field of bone tissue engineering. To date, the mechanical strength of 3D printed ceramic scaffolds is not sufficient for a variety of applications in the reconstructive surgery. Mechanical strength is directly in relation with the porosity of the 3D printed scaffolds. The porosity is directly influenced by particle size and particle-size distribution of the raw material. To investigate this impact, a hydroxyapatite granule blend with a wide particle size distribution was fractioned by sieving. The specific fractions and bimodal mixtures of the sieved granule blend were used to 3D print specimens. It has been shown that an optimized arrangement of fractions with large and small particles can provide 3D printed specimens with good mechanical strength due to a higher packing density. An increase of mechanical strength can possibly expand the application area of 3D printed hydroxyapatite scaffolds.

  7. Double porosity models for the description of water infiltration in wood

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Damkilde, Lars

    2004-01-01

    In this paper some of the possibilities of applying double porosity and permeability models to the problem of water infiltration in wood are explored. It is shown that the double porosity model can capture a number of commonly reported anomalies including two-stage infiltration/sorption and appar......In this paper some of the possibilities of applying double porosity and permeability models to the problem of water infiltration in wood are explored. It is shown that the double porosity model can capture a number of commonly reported anomalies including two-stage infiltration...

  8. Prediction of soil water retention properties using pore-size distribution and porosity

    National Research Council Canada - National Science Library

    Beckett, Christopher T.S; Augarde, Charles E

    2013-01-01

    .... This paper presents a method that builds on previous techniques by incorporating porosity and particles of different sizes, shapes, and separation distances to predict soil water retention properties...

  9. Effect of shrinkage porosity on mechanical properties of ferritic ductile iron

    Directory of Open Access Journals (Sweden)

    Wang Zehua

    2013-05-01

    Full Text Available Casting defects could largely affect the mechanical properties of casting products. A number of test pieces made of ductile iron (EN-GJS-400-18-LT with different levels of shrinkage porosity were prepared and then tensile and fatigue tests were performed to investigate the impact of shrinkage porosity on their mechanical properties. The results showed that the tensile strength decreases linearly with increasing of the shrinkage porosity. The tensile elongation decreases sharply with the increase of the shrinkage porosity mainly due to the non-uniform plastic deformation. The fatigue life also dramatically declines with increasing of the porosity and follows a power law relationship with the area percentage of porosity. The existence of the shrinkage porosity made the fatigue fracture complex. The shrinkage pores, especially those close to the surface usually became the crack initiation sites. For test pieces with less porosity, the fatigue fracture was clearly composed of crack initiation, propagation, and overloading. While for samples with high level of porosity, multiple crack initiation sites were observed.

  10. Double Porosity Models For the Description of Water Infiltration In Wood

    DEFF Research Database (Denmark)

    Kristian, Krabbenhøft; Damkilde, Lars

    2004-01-01

    In this paper some of the possibilities of applying double porosity and permeability models to the problem of water infiltration in wood are explored. It is shown that the double porosity model can capture a number of commonly reported anomalies including two-stage infiltration/sorption and appar......In this paper some of the possibilities of applying double porosity and permeability models to the problem of water infiltration in wood are explored. It is shown that the double porosity model can capture a number of commonly reported anomalies including two-stage infiltration...

  11. Medicare Provider Data - Hospice Providers

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Hospice Utilization and Payment Public Use File provides information on services provided to Medicare beneficiaries by hospice providers. The Hospice PUF...

  12. Eggshell porosity covaries with egg size among female House Wrens (Troglodytes aedon) but is unrelated to incubation onset and egg-laying order within clutches

    Science.gov (United States)

    Bowers, E.K.; White, A.; Lang, A.; Podgorski, L.; Thompson, C.F.; Sakaluk, S.K.; Jaeckle, W.B.; Harper, R.G.

    2015-01-01

    In birds, the duration of egg incubation (the time from incubation onset to hatching) can affect multiple components of nest success, but what affects incubation duration? Previous studies suggest that incubation duration is affected by both parental behavior and components of the egg, which have yet to be determined. One egg component that may be related to incubation behavior and the time until hatching is eggshell porosity, which affects the exchange of metabolic gasses and water vapor across the shell and, thus, the speed of embryonic development and incubation duration. We tested whether eggshell porosity was associated with the timing of incubation onset by female House Wrens (Troglodytes aedon Vieillot, 1809), and whether porosity varied within clutches in a manner that might be associated with incubation periods and hatching patterns (i.e., synchronous vs. asynchronous hatching). Eggshell porosity was unrelated to the onset of maternal incubation and did not differ between early and later-laid eggs within clutches, but differed significantly among females and covaried with egg size. We conclude that producing all eggshells of similar porosity within clutches, while adjusting incubation onset once most or all eggs are laid, provide facultative maternal control over variation in hatching patterns. PMID:26146408

  13. Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

    Directory of Open Access Journals (Sweden)

    Y. Luna-Galiano

    2016-09-01

    Full Text Available The main contribution of this paper relates to the development of a systematic study involving a set of parameters which could potentially have an impact on geopolymer properties: curing temperature, type of activating solution, alkali metal in solution, incorporation of slag (Ca source and type of slag used. The microstructures, degrees of reaction, porosities and compressive strengths of geopolymers have been evaluated. Geopolymers prepared with soluble silicate presented a more compacted and closed structure, a larger amount of gel, lower porosity and greater compressive strength than those prepared with hydroxides. On the other hand, Na-geopolymers were more porous but more resistant than K-geopolymers. Although there is an inverse relation between degree of reaction and porosity, between compressive strength and porosity it is not always inversely proportional and could, in some cases, be masked by changes produced in other influencing parameters.

  14. Titanium-Phosphonate-Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

    KAUST Repository

    Li, Hui

    2018-02-01

    Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. Herein a new photocatalyst of hierarchically mesoporous titanium-phosphonate-based metal-organic frameworks, featuring well-structured spheres, periodic mesostructure and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemical field.

  15. Investigation of the mechanical properties and porosity relationships in selective laser-sintered polyhedral for functionally graded scaffolds.

    Science.gov (United States)

    Sudarmadji, N; Tan, J Y; Leong, K F; Chua, C K; Loh, Y T

    2011-02-01

    An important requirement for a bone tissue engineering scaffold is a stiffness gradient that mimics that of native bone. Such scaffolds can be achieved by controlling their structure and porosity and are termed functionally graded scaffolds (FGS). Currently, the main challenges in FGS fabrication include the iterative and tedious design process as well as a heavy reliance on the user's CAD/CAM skills. This work aims to bring automated FGS production a step closer by providing a database that correlates scaffold porosity values and the corresponding compressive stiffness and integrating it into the design process. To achieve this goal, scaffolds with different structural configurations were designed using CASTS (Computer Aided System for Tissue Scaffolds), an in-house developed library system consisting of 13 different polyhedral units that can be assembled into scaffold structures. Polycaprolactone (PCL) was chosen as the scaffold material, while selective laser sintering, a powder-based rapid prototyping or additive manufacturing system was employed to fabricate the scaffolds. Mathematical relations correlating scaffold porosity and compressive stiffness readings were formulated and compiled. In addition, cytotoxicity assessment was conducted to evaluate the toxicity of the fabricated PCL scaffolds. Lastly, a brief demonstration of how the formulated relations are used in the FGS design process is presented. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Open access

    NARCIS (Netherlands)

    Valkenburg, P.M.

    2015-01-01

    Open access week Van 19 tot en met 25 oktober 2015 vond wereldwijd de Open Access Week plaats. Tijdens deze week werden er over de hele wereld evenementen georganiseerd waar open access een rol speelt. Ook in Nederland zijn er diverse symposia, workshops en debatten georganiseerd zoals het debat in

  17. Plasma sintering of unalloyed iron: a study of surface porosity

    Directory of Open Access Journals (Sweden)

    Lourenço Jorge Magner

    2004-01-01

    Full Text Available Samples of unalloyed iron powder were compacted and sintered in an abnormal glow discharge, generated in a gas mixture of 80% Ar + 20% H2 by using a pulsed power source. The samples were placed on a holder, acting as the discharge cathode, and were heated by the bombardment of ions, strongly accelerated in the cathode sheath. Sintering was performed at temperatures of 1173, 1273 and 1373 K for 30 min, varying the voltage applied to the cathode from 400 to 700 V and pressure ranging from 470 to 2650 Pa. It is shown that the kinetic energy of ions striking the sample surface increased approximately three times, when the voltage changed from 400 to 700 V, with a corresponding reduction of surface porosity. The surface sealing is related to the ion bombardment, which produced a high mobility of surface atoms and consequent enhanced diffusion as well as sputtering and condensation on the concave surface, resulting in an activation of surface sintering.

  18. The Porosity of the neutral ISM in 20 THINGS Galaxies

    Science.gov (United States)

    Bagetakos, I.; Brinks, E.; Walter, F.; de Blok, W. J. G.; Usero, A.; Leroy, A. K.; Rich, J. W.; Kennicutt, R. C.

    2011-11-01

    We present an analysis of the properties of H i holes detected in 20 galaxies that are part of "The H i Nearby Galaxy Survey". We detected more than 1000 holes in total in the sampled galaxies. The holes are found throughout the disks of the galaxies, out to the edge of the H i disk. We find that shear limits the age of holes in spirals. Shear is less important in dwarf galaxies which explains why H i holes in dwarfs are rounder, on average than in spirals. Shear is particularly strong in the inner part of spiral galaxies, limiting the lifespan of holes there and explaining why we find that holes outside R25 are larger and older. We proceed to derive the surface and volume porosity and find that this correlates with the type of the host galaxy: later Hubble types tend to be more porous. The size distribution of the holes in our sample follows a power law with a slope of aν ~ -2.9. Assuming that the holes are the result of massive star formation, we derive values for the supernova rate (SNR) and star formation rate (SFR) which scales with the SFR derived based on other tracers. If we extrapolate the observed number of holes to include those that fall below our resolution limit, down to holes created by a single supernova, we find that our results are compatible with the hypothesis that H i holes result from star formation.

  19. Boiling radial flow in fractures of varying wall porosity

    Energy Technology Data Exchange (ETDEWEB)

    Barnitt, Robb Allan

    2000-06-01

    The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials. Nonporous and impermeable aluminum, highly porous and permeable Berea sandstone, and minimally porous and permeable graywacke from The Geysers geothermal field. On nonporous surfaces, the heat flux was not strongly coupled to injection rate into the fracture. However, for porous surfaces, heat flux, and associated values of excess temperature and a boiling convection coefficient exhibited variation with injection rate. Nucleation was shown to occur not upon the visible surface of porous materials, but a distance below the surface, within the matrix. The depth of boiling was a function of injection rate, thermal power supplied to the fracture, and the porosity and permeability of the rock. Although matrix boiling beyond fracture wall may apply only to a finite radius around the point of injection, higher values of heat flux and a boiling convection coefficient may be realized with boiling in a porous, rather than nonporous surface bounded fracture.

  20. Thermochemistry of zeolitic imidazolate frameworks of varying porosity.

    Science.gov (United States)

    Hughes, James T; Bennett, Thomas D; Cheetham, Anthony K; Navrotsky, Alexandra

    2013-01-16

    The first thermochemical analysis by room-temperature aqueous solution calorimetry of a series of zeolite imidazolate frameworks (ZIFs) has been completed. The enthalpies of formation of the evacuated ZIFs-ZIF-zni, ZIF-1, ZIF-4, CoZIF-4, ZIF-7, and ZIF-8-along with as-synthesized ZIF-4 (ZIF-4·DMF) and ball-milling amorphized ZIF-4 (a(m)ZIF-4) were measured with respect to dense components: metal oxide (ZnO or CoO), the corresponding imidazole linker, and N,N dimethylformamide (DMF) in the case of ZIF-4·DMF. Enthalpies of formation of ZIFs from these components at 298 K are exothermic, but the ZIFs are metastable energetically with respect to hypothetical dense components in which zinc is bonded to nitrogen rather than oxygen. These enthalpic destabilizations increase with increasing porosity and span a narrow range from 13.0 to 27.1 kJ/mol, while the molar volumes extend from 135.9 to 248.8 cm(3)/mol; thus, almost doubling the molar volume results in only a modest energetic destabilization. The experimental results are supported by DFT calculations. The series of ZIFs studied tie in with previously studied MOF-5, creating a broader trend that mirrors a similar pattern by porous inorganic oxides, zeolites, zeotypes, and mesoporous silicas. These findings suggest that no immediate thermodynamic barrier precludes the further development of highly porous materials.

  1. Patterning of dispenser cathode surfaces to a controlled porosity

    Science.gov (United States)

    Garner, Charles E.; Deininger, William D.; Gibson, John; Thomas, Richard

    1989-01-01

    A process to pattern slots approximately 1.25 microns in width into 25-micron-thick W films that have been deposited onto flat or concave surfaces is discussed. A 25-micron-thick W film with a high degree of (100) orientation is chemically vapor deposited (CVD) onto a flat or concave Mo mandrel. A 5-micron-thick Al film is deposited onto the CVD W, followed by 2 microns of photoresist. On concave cathodes, XeCl2 laser ablation or X-ray lithography is used to pattern the photoresist, whereas on flat cathodes deep UV lithography can be used. The patterned photoresist serves as the mask in a Cl ion-beam-assisted etching (IBAE) process to pattern the Al. An alternative process is to deposit Al2O3 films onto the W and pattern the Al2O3 using laser ablation. The W film is then patterned to 3-6-micron slot widths using IBAE + ClF3 with the patterned Al or Al2O3 as the mask. Finally, a sputter deposition step is required to close up the slots to approximately 1 micron. The process described is capable of patterning concave dispenser cathodes to a controlled and precise porosity.

  2. Compaction and gas loss in welded pyroclastic deposits as revealed by porosity, permeability, and electrical conductivity measurements of the Shevlin Park Tuff

    Science.gov (United States)

    Wright, Heather M.; Cashman, Katharine V.

    2014-01-01

    Pyroclastic flows produced by large volcanic eruptions commonly densify after emplacement. Processes of gas escape, compaction, and welding in pyroclastic-flow deposits are controlled by the physical and thermal properties of constituent material. Through measurements of matrix porosity, permeability, and electrical conductivity, we provide a framework for understanding the evolution of pore structure during these processes. Using data from the Shevlin Park Tuff in central Oregon, United States, and from the literature, we find that over a porosity range of 0%–70%, matrix permeability varies by almost 10 orders of magnitude (from 10–20 to 10–11 m2), with over three orders of magnitude variation at any given porosity. Part of the variation at a given porosity is due to permeability anisotropy, where oriented core samples indicate higher permeabilities parallel to foliation (horizontally) than perpendicular to foliation (vertically). This suggests that pore space is flattened during compaction, creating anisotropic crack-like networks, a geometry that is supported by electrical conductivity measurements. We find that the power law equation: k1 = 1.3 × 10–21 × ϕ5.2 provides the best approximation of dominant horizontal gas loss, where k1 = permeability, and ϕ = porosity. Application of Kozeny-Carman fluid-flow approximations suggests that permeability in the Shevlin Park Tuff is controlled by crack- or disk-like pore apertures with minimum widths of 0.3 and 7.5 μm. We find that matrix permeability limits compaction over short times, but deformation is then controlled by competition among cooling, compaction, water resorption, and permeable gas escape. These competing processes control the potential for development of overpressure (and secondary explosions) and the degree of welding in the deposit, processes that are applicable to viscous densification of volcanic deposits in general. Further, the general relationships among porosity, permeability, and

  3. Olive Crown Porosity Measurement Based on Radiation Transmittance: An Assessment of Pruning Effect

    Directory of Open Access Journals (Sweden)

    Francisco J. Castillo-Ruiz

    2016-05-01

    Full Text Available Crown porosity influences radiation interception, air movement through the fruit orchard, spray penetration, and harvesting operation in fruit crops. The aim of the present study was to develop an accurate and reliable methodology based on transmitted radiation measurements to assess the porosity of traditional olive trees under different pruning treatments. Transmitted radiation was employed as an indirect method to measure crown porosity in two olive orchards of the Picual and Hojiblanca cultivars. Additionally, three different pruning treatments were considered to determine if the pruning system influences crown porosity. This study evaluated the accuracy and repeatability of four algorithms in measuring crown porosity under different solar zenith angles. From a 14° to 30° solar zenith angle, the selected algorithm produced an absolute error of less than 5% and a repeatability higher than 0.9. The described method and selected algorithm proved satisfactory in field results, making it possible to measure crown porosity at different solar zenith angles. However, pruning fresh weight did not show any relationship with crown porosity due to the great differences between removed branches. A robust and accurate algorithm was selected for crown porosity measurements in traditional olive trees, making it possible to discern between different pruning treatments.

  4. Effect of porosity and pore morphology on the low-frequency ...

    Indian Academy of Sciences (India)

    the imperfections, e.g. porosity, impurities, grain boundaries, micro-cracks, ran- dom crystal orientations etc. It is evident from the earlier studies [1–3] that the losses in sintered polycrystalline ceramics are strongly affected by these extrinsic factors. Few of the earlier work deals with the effect of only total porosity on the. 309 ...

  5. Investigation of surface porosity measurements and compaction pressure as means to ensure consistent contact angle determinations

    DEFF Research Database (Denmark)

    Holm, René; Borkenfelt, Simon; Allesø, Morten

    2016-01-01

    .g. increase the wetting from a solid dosage form. Since surface roughness of the compact has been suggested to influence the measurement this study investigated if the surface quality, in terms of surface porosity, had an influence on the measured contact angle. A correlation to surface porosity was observed...

  6. Porosity testing methods for the quality assessment of selective laser melted parts

    NARCIS (Netherlands)

    Wits, Wessel W.; Carmignato, Simone; Zanini, Filippo; Vaneker, Thomas H.J.

    2016-01-01

    This study focuses on the comparison of porosity testing methods for the quality assessment of selective laser melted parts. Porosity is regarded as important quality indicator in metal additive manufacturing. Various destructive and non-destructive testing methods are compared, ranging from global

  7. Geometry Properties of Porosity Waves during Magma Migration: The Influence of Viscosities and Damage

    Science.gov (United States)

    Cai, Z.; Bercovici, D.

    2014-12-01

    Partial melting occurs along grain boundaries and migrates through porous flow, leading to magma segregation in the mantle. Solitary porosity waves created by a perturbation in melting have been studied in the flow of a low viscosity fluid in a deformable matrix (McKenzie 1984, Scott and Stevenson 1986, Barcilon and Richter 1986, Spiegelman 1993, Wiggins and Spiegelman 1995). However, in a fairly complicated multi-physics, multi-scale process of magma migration, the geometry and instability of porosity waves can be affected by both mechanical and thermal factors, leaving different propagation signatures. In this work we develop a two-dimensional, two-phase damage model of magma-fracturing, and study the influence of viscosities and damage (void generation and microcracking) on the geometry properties of porosity waves. We first benchmark our solitary solutions with previous works and solve 2-D finite-amplitude waves numerically using spectral and semi-spectral method. We show that damage, decompaction weakening of the matrix and porosity-driven viscosities can alter the geometry of stable porosity waves, and result in an elongated or flattened wave front with a trail of smaller porosity. Such trails may localize subsequent waves and form porosity passage in the matrix. Scaling analysis of the time-dependent porosity waves are conducted and amount of magma reaching to the top of the melting region are estimated. Future work will include evaluating the thermal and seismic signatures during and after melt migration in two-phase porous flow.

  8. Ultrasonic velocities of North Sea chalk samples: influence of porosity, fluid content and texture

    DEFF Research Database (Denmark)

    Rogen, B.; Fabricius, Ida Lykke; Japsen, P.

    2005-01-01

    a porosity-reducing effect and that samples rich in large grains have a relatively low porosity for a given P-wave modulus. The clay content in the samples is low and is mainly represented by either kaolinite or smectite; samples with smectite have a lower P-wave modulus than samples with kaolinite at equal...

  9. Effect of static porosity fluctuations on reactive transport in a porous medium

    Science.gov (United States)

    L'Heureux, Ivan

    2018-02-01

    Reaction-diffusive transport phenomena in porous media are ubiquitous in engineering applications, biological and geochemical systems. The porosity field is usually random in space, but most models consider the porosity field as a well-defined deterministic function of space and time and ignore the porosity fluctuations. They use a reaction-diffusion equation written in terms of an average porosity and average concentration fields. In this contribution, we treat explicitly the effect of spatial porosity fluctuations on the dynamics of a concentration field for the case of a one-dimensional reaction-transport system with nonlinear kinetics. Three basic assumptions are considered. (i) The porosity fluctuations are assumed to have Gaussian properties and an arbitrary variance; (ii) we assume that the noise correlation length is small compared to the relevant macroscopic length scale; (iii) and we assume that the kinetics of the reactive term in the equations for the fluctuations is a self-consistently determined constant. Elimination of the fluctuating part of the concentration field from the dynamics leads to a renormalized equation involving the average concentration field. It is shown that the noise leads to a renormalized (generally smaller) diffusion coefficient and renormalized kinetics. Within the framework of the approximations used, numerical simulations are in agreement with our theory. We show that the porosity fluctuations may have a significant effect on the transport of a reactive species, even in the case of a homogeneous average porosity.

  10. Effect of porosity on the tensile properties of low ductility aluminum alloys

    Directory of Open Access Journals (Sweden)

    Gustavo Waldemar Mugica

    2004-06-01

    Full Text Available The literature contains reports of several studies correlating the porosity and mechanical properties of aluminum alloys. Most of these studies determine this correlation based on the parameter of global volumetric porosity. These reports, however, fail to separate the effects of microstructural features and porosity on alloys, though recognizing the influence of the latter on their mechanical properties. Thus, when the decrease in tensile strength due to the porosity effect is taken into account, the findings are highly contradictory. An analysis was made of the correlation between mechanical properties and global volumetric porosity and volumetric porosity in the fracture, as well as of the beta-Al5FeSi phase present in 380 aluminum alloy. Our findings indicate that mechanical properties in tension relating to global volumetric porosity lead to overestimations of the porosity effect in detriment to the mechanical properties. Moreover, the proposed models that take into account the effects of particles, both Si and beta-Al5FeSi, are unapplicable to low ductility alloys.

  11. Open algebraic surfaces

    CERN Document Server

    Miyanishi, Masayoshi

    2000-01-01

    Open algebraic surfaces are a synonym for algebraic surfaces that are not necessarily complete. An open algebraic surface is understood as a Zariski open set of a projective algebraic surface. There is a long history of research on projective algebraic surfaces, and there exists a beautiful Enriques-Kodaira classification of such surfaces. The research accumulated by Ramanujan, Abhyankar, Moh, and Nagata and others has established a classification theory of open algebraic surfaces comparable to the Enriques-Kodaira theory. This research provides powerful methods to study the geometry and topology of open algebraic surfaces. The theory of open algebraic surfaces is applicable not only to algebraic geometry, but also to other fields, such as commutative algebra, invariant theory, and singularities. This book contains a comprehensive account of the theory of open algebraic surfaces, as well as several applications, in particular to the study of affine surfaces. Prerequisite to understanding the text is a basic b...

  12. Open Access @ DTU

    DEFF Research Database (Denmark)

    Ekstrøm, Jeannette

    Open Access is high on the agenda in Denmark and internationally. Denmark has announced a national strategy for Open Access that aims to achieve Open Access to 80% in 2017 and 100% in 2022 to peer review research articles. All public Danish funders as well as H2020 requires that all peer review...... articles that is an outcome of their funding will be Open Access. Uploading your full texts (your final author manuscript after review ) to DTU Orbit is a fundamental part of providing Open Access to your research. We are here to answer all your questions with regards to Open Access and related topics...... such as copyright, DTU Orbit, Open Access journals, APCs, Vouchers etc....

  13. Predicting Frost Resistance of Concrete with Different Coarse Aggregate Concentration by Porosity Parameters

    Directory of Open Access Journals (Sweden)

    Džigita NAGROCKIENĖ

    2011-07-01

    Full Text Available Frost resistance is one of the key indicators of concrete quality. Frost resistance can be determined by direct testing; however it is time-consuming and labour-intensive method. Concrete decomposition is a complex process (from initial signs of degradation to complete failure of the surface subjected to freezing involving many factors. Frost resistance of concrete can be predicted from porosity parameters after determining their relation to frost resistance. Test results showed the relation between the closed porosity of concrete and frost resistance factor. Closed porosity of concrete was found to have a significant influence on frost resistance factor. It is shown that closed porosity depends on the concentration of coarse aggregate in concrete, the closed porosity and predicted frost resistance of concrete increase with lower concentration of coarse aggregate.http://dx.doi.org/10.5755/j01.ms.17.2.493

  14. Open port sampling interface

    Science.gov (United States)

    Van Berkel, Gary J

    2017-04-25

    A system for sampling a sample material includes a probe which can have an outer probe housing with an open end. A liquid supply conduit within the housing has an outlet positioned to deliver liquid to the open end of the housing. The liquid supply conduit can be connectable to a liquid supply for delivering liquid at a first volumetric flow rate to the open end of the housing. A liquid exhaust conduit within the housing is provided for removing liquid from the open end of the housing. A liquid exhaust system can be provided for removing liquid from the liquid exhaust conduit at a second volumetric flow rate, the first volumetric flow rate exceeding the second volumetric flow rate, wherein liquid at the open end will receive sample, liquid containing sample material will be drawn into and through the liquid exhaust conduit, and liquid will overflow from the open end.

  15. Open port sampling interface

    Energy Technology Data Exchange (ETDEWEB)

    Van Berkel, Gary J.

    2018-01-16

    A system for sampling a sample material includes a probe which can have an outer probe housing with an open end. A liquid supply conduit within the housing has an outlet positioned to deliver liquid to the open end of the housing. The liquid supply conduit can be connectable to a liquid supply for delivering liquid at a first volumetric flow rate to the open end of the housing. A liquid exhaust conduit within the housing is provided for removing liquid from the open end of the housing. A liquid exhaust system can be provided for removing liquid from the liquid exhaust conduit at a second volumetric flow rate, the first volumetric flow rate exceeding the second volumetric flow rate, wherein liquid at the open end will receive sample, liquid containing sample material will be drawn into and through the liquid exhaust conduit, and liquid will overflow from the open end.

  16. Evolution of porosity and diffusivity associated with chemical weathering of a basalt clast

    Energy Technology Data Exchange (ETDEWEB)

    Navarre-Sitchler, A.; Steefel, C.I.; Yang, L.; Tomutsa, L.; Brantley, S.L.

    2009-02-15

    Weathering of rocks as a result of exposure to water and the atmosphere can cause significant changes in their chemistry and porosity. In low-porosity rocks, such as basalts, changes in porosity, resulting from chemical weathering, are likely to modify the rock's effective diffusivity and permeability, affecting the rate of solute transport and thus potentially the rate of overall weathering to the extent that transport is the rate limiting step. Changes in total porosity as a result of mineral dissolution and precipitation have typically been used to calculate effective diffusion coefficients through Archie's law for reactive transport simulations of chemical weathering, but this approach fails to account for unconnected porosity that does not contribute to transport. In this study, we combine synchrotron X-ray microcomputed tomography ({mu}CT) and laboratory and numerical diffusion experiments to examine changes in both total and effective porosity and effective diffusion coefficients across a weathering interface in a weathered basalt clast from Costa Rica. The {mu}CT data indicate that below a critical value of {approx}9%, the porosity is largely unconnected in the basalt clast. The {mu}CT data were further used to construct a numerical pore network model to determine upscaled, effective diffusivities as a function of total porosity (ranging from 3 to 30%) for comparison with diffusivities determined in laboratory tracer experiments. By using effective porosity as the scaling parameter and accounting for critical porosity, a model is developed that accurately predicts continuum-scale effective diffusivities across the weathering interface of the basalt clast.

  17. Porosity and distribution of water in perlite from the island of Milos, Greece.

    Science.gov (United States)

    Kaufhold, Stephan; Reese, Anke; Schwiebacher, Werner; Dohrmann, Reiner; Grathoff, Georg H; Warr, Laurence N; Halisch, Matthias; Müller, Cornelia; Schwarz-Schampera, Ulrich; Ufer, Kristian

    2014-01-01

    A perlite sample representative of an operating mine in Milos was investigated with respect to the type and spatial distribution of water. A set of different methods was used which finally provided a consistent view on the water at least in this perlite. Infrared spectroscopy showed the presence of different water species (molecular water and hydroxyl groups / strongly bound water). The presence of more than 0.5 mass% smectite, however, could be excluded considering the cation exchange capacity results. The dehydration measured by thermal analysis occurred over a wide range of temperatures hence confirming the infrared spectroscopical results. Both methods point to the existence of a continuous spectrum of water binding energies. The spatial distribution of water and/or pores was investigated using different methods (CT: computer tomography, FIB: scanning electron microscopy including focused ion beam technology, IRM: infrared microscopy). Computer tomography (CT) showed large macropores (20 - 100 μm) and additionally revealed a mottled microstructure of the silicate matrix with low density areas up to a few μm in diameter. Scanning electron microscopy (FIB) confirmed the presence of μm sized pores and IRM showed the filling of these pores with water. In summary, two types of pores were found. Airfilled 20 - 100 μm pores and μm-sized pores disseminated in the glass matrix containing at least some water. Porosity measurements indicate a total porosity of 26 Vol%, 11 Vol% corresponding to the μm-sized pores. It remains unsolved wether the water in the μm-sized pores entered after or throughout perlite formation. However, the pores are sealed and no indications of cracks were found which indicated a primary source of the water, i.e. water was probably entrapped by quenching of the lava. The water in these pores may be the main reason for the thermal expandability which results in the extraordinarily porous expanded perlite building materials.

  18. Critical porosity of gas enclosure in polar firn independent of climate

    Science.gov (United States)

    Florian Schaller, Christoph; Freitag, Johannes; Eisen, Olaf

    2017-11-01

    In order to interpret the paleoclimatic record stored in the air enclosed in polar ice cores, it is crucial to understand the fundamental lock-in process. Within the porous firn, bubbles are sealed continuously until the respective horizontal layer reaches a critical porosity. Present-day firn air models use a postulated temperature dependence of this value as the only parameter to adjust to the surrounding conditions of individual sites. However, no direct measurements of the firn microstructure could confirm these assumptions. Here we show that the critical porosity is a climate-independent constant by providing an extensive data set of micrometer-resolution 3-D X-ray computer tomographic measurements for ice cores representing different extremes of the temperature and accumulation ranges. We demonstrate why indirect measurements suggest a climatic dependence and substantiate our observations by applying percolation theory as a theoretical framework for bubble trapping. The incorporation of our results significantly influences the dating of trace gas records, changing gas-age-ice-age differences by up to more than 1000 years. This may further help resolve inconsistencies, such as differences between East Antarctic δ15N records (as a proxy for firn height) and model results. We expect our findings to be the basis for improved firn air and densification models, leading to lower dating uncertainties. The reduced coupling of proxies and surrounding conditions may allow for more sophisticated reinterpretations of trace gas records in terms of paleoclimatic changes and will benefit the development of new proxies, such as the air content as a marker of local insolation.

  19. Hydrodynamics of mangrove-type root models: the effect of porosity, spacing ratio and flexibility.

    Science.gov (United States)

    Kazemi, Amirkhosro; Van de Riet, Keith; Curet, Oscar M

    2017-09-21

    Mangrove trees play a prominent role in coastal tropic and subtropical regions, providing habitats for many organisms and protecting shorelines against high energy flows. In particular, the species Rhizophora mangle (red mangrove) exhibits complex cluster roots interacting with different hydrological flow conditions. To better understand the resilience of mangrove trees, we modeled the roots as a collection of cylinders with a circular pattern subject to unidirectional flow. We investigated the effect of porosity and spacing ratio between roots by varying both the diameter of the patch, D, and inset cylinders, d. In addition, we modeled hanging roots of red mangroves as cantilevered rigid cylinders on a hinge. Force and velocity measurements were performed in a water tunnel (Reynolds numbers from 2200 to 11 000). Concurrently, we performed 2D flow visualization using a flowing soap film. We found that the frequency of the vortex shedding increases as the diameter of the small cylinders decreases while the patch diameter is constant, therefore increasing the Strouhal number, [Formula: see text]. By comparing the change of Strouhal numbers with a single solid cylinder, we introduced a new length scale, the effective diameter. The effective diameter of the patch decreases as the porosity increases. In addition, we found that patch drag scales linearly with the patch diameter but decreases linearly as the spacing ratio increases. After a spacing ratio of ([Formula: see text]), the force scales linearly with the free stream velocity, and the mean velocity behind the patch is independent of the Reynolds number and the patch effect disappears. For flexible cylinders, we found that a decrease in stiffness increases both patch drag and the wake deficit behind the patch in a similar fashion as increasing the blockage of the patch. This information has the potential to help in the development of methods to design resilient bio-inspired coastline structures.

  20. Geochemical and Mineralogical Evaluation of CO2-Brine-Rock Experiments: Characterizing Porosity and Permeability Variations in the Cambrian Mount Simon Sandstone

    Science.gov (United States)

    Gonzalez, A. B.; Bowen, B. B.

    2012-12-01

    in major ion and trace element concentration suggesting that dissolution of soluble phases occurred during the experiment. 174 precisely placed SEM/EDX measurements of overall elemental composition and 144 pores from the interior of the samples (presumably not in contact with the CO2 and brine) and the exterior edges of the samples (in direct contact with the CO2 and brine) show variations in cation concentration and pore-filling textures. In general, the sample interiors have more open pores and the edges have higher cation concentrations and pores filled with secondary minerals. Current results indicate carbon dioxide injection into samples from the same formation but dissimilar textural and mineral compositions can have variable affects on overall permeability and porosity.

  1. Visualizing bone porosities using a tabletop scanning electron microscope

    Science.gov (United States)

    Krishnamoorthy, D.; DaPonte, J.; Broadbridge, C. C.; Daniel, D.; Alter, L.

    2010-04-01

    Pores are naturally occurring entities in bone. Changes in pore size and number are often associated with diseases such as Osteoporosis and even microgravity during spaceflight. Studying bone perforations may yield great insight into bone's material properties, including bone density and may contribute to identifying therapies to halt or potentially reverse bone loss. Current technologies used in this field include nuclear magnetic resonance, micro-computed tomography and the field emission scanning electron microscope (FE-SEM) 2, 5. However, limitations in each method limit further advancement. The objective of this study was to assess the effectiveness of using a new generation of analytical instruments, the TM-1000 tabletop, SEM with back-scatter electron (BSE) detector, to analyze cortical bone porosities. Hind limb unloaded and age-based controlled mouse femurs were extracted and tested in vitro for changes in pores on the periosteal surface. An important advantage of using the tabletop is the simplified sample preparation that excludes extra coatings, dehydration and fixation steps that are otherwise required for conventional SEM. For quantitative data, pores were treated as particles in order to use an analyze particles feature in the NIH ImageJ software. Several image-processing techniques for background smoothing, thresholding and filtering were employed to produce a binary image suitable for particle analysis. It was hypothesized that the unloaded bones would show an increase in pore area, as the lack of mechanical loading would affect bone-remodeling processes taking place in and around pores. Preliminary results suggest only a slight different in frequency but not in size of pores between unloaded and control femurs.

  2. Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?

    Science.gov (United States)

    Torstrick, F Brennan; Evans, Nathan T; Stevens, Hazel Y; Gall, Ken; Guldberg, Robert E

    2016-11-01

    Despite its widespread use in orthopaedic implants such as soft tissue fasteners and spinal intervertebral implants, polyetheretherketone (PEEK) often suffers from poor osseointegration. Introducing porosity can overcome this limitation by encouraging bone ingrowth; however, the corresponding decrease in implant strength can potentially reduce the implant's ability to bear physiologic loads. We have previously shown, using a single pore size, that limiting porosity to the surface of PEEK implants preserves strength while supporting in vivo osseointegration. However, additional work is needed to investigate the effect of pore size on both the mechanical properties and cellular response to PEEK. (1) Can surface porous PEEK (PEEK-SP) microstructure be reliably controlled? (2) What is the effect of pore size on the mechanical properties of PEEK-SP? (3) Do surface porosity and pore size influence the cellular response to PEEK? PEEK-SP was created by extruding PEEK through NaCl crystals of three controlled ranges: 200 to 312, 312 to 425, and 425 to 508 µm. Micro-CT was used to characterize the microstructure of PEEK-SP. Tensile, fatigue, and interfacial shear tests were performed to compare the mechanical properties of PEEK-SP with injection-molded PEEK (PEEK-IM). The cellular response to PEEK-SP, assessed by proliferation, alkaline phosphatase activity, vascular endothelial growth factor production, and calcium content of osteoblast, mesenchymal stem cell, and preosteoblast (MC3T3-E1) cultures, was compared with that of machined smooth PEEK and Ti6Al4V. Micro-CT analysis showed that PEEK-SP layers possessed pores that were 284 ± 35 µm, 341 ± 49 µm, and 416 ± 54 µm for each pore size group. Porosity and pore layer depth ranged from 61% to 69% and 303 to 391 µm, respectively. Mechanical testing revealed tensile strengths > 67 MPa and interfacial shear strengths > 20 MPa for all three pore size groups. All PEEK-SP groups exhibited > 50% decrease

  3. Investigation of the influence of the open cell foam models geometry on hydrodynamic calculation

    Science.gov (United States)

    Soloveva, O. V.; Solovev, S. A.; Khusainov, R. R.; Popkova, O. S.; Panenko, D. O.

    2018-01-01

    A geometrical model of the open cell foam was created as an ordered set of intersecting spheres. The proposed model closely describes a real porous cellular structure. The hydrodynamics flow was calculated on the basis of a simple model in the ANSYS Fluent software package. A pressure drop was determined, the value of which was compared with the experimental data of other authors. As a result of the conducted studies, we found that a porous structure with smoothed faces provides the smallest pressure drop with the same porosity of the package. Analysis of the calculated data demonstrated that the approximation of an elementary porous cell substantially distorts the flow field. This is undesirable in detailed modeling of the open cell foam.

  4. Effect of Matrix-Wellbore Flow and Porosity on Pressure Transient Response in Shale Formation Modeling by Dual Porosity and Dual Permeability System

    Directory of Open Access Journals (Sweden)

    Daolun Li

    2015-01-01

    Full Text Available A mathematical dual porosity and dual permeability numerical model based on perpendicular bisection (PEBI grid is developed to describe gas flow behaviors in shale-gas reservoirs by incorporating slippage corrected permeability and adsorbed gas effect. Parametric studies are conducted for a horizontal well with multiple infinite conductivity hydraulic fractures in shale-gas reservoir to investigate effect of matrix-wellbore flow, natural fracture porosity, and matrix porosity. We find that the ratio of fracture permeability to matrix permeability approximately decides the bottom hole pressure (BHP error caused by omitting the flow between matrix and wellbore and that the effect of matrix porosity on BHP is related to adsorption gas content. When adsorbed gas accounts for large proportion of the total gas storage in shale formation, matrix porosity only has a very small effect on BHP. Otherwise, it has obvious influence. This paper can help us understand the complex pressure transient response due to existence of the adsorbed gas and help petroleum engineers to interpret the field data better.

  5. Characterization of the porosity distribution in the upper part of the karst Biscayne aquifer using common offset ground penetrating radar, Everglades National Park, Florida

    Science.gov (United States)

    Mount, Gregory J.; Comas, Xavier; Cunningham, Kevin J.

    2014-07-01

    the direct porosity values from the whole-core samples confirms the ability of GPR common offset surveys to provide rapid characterization of porosity variability in the Biscayne aquifer. The common offset survey method has several advantages: (1) improved time efficiency in comparison to other GPR acquisition modes such as common midpoints; and (2) enhanced lateral continuity of porosity estimates, particularly when compared to porosity measurements on 1-D samples such as rock cores. The results also support the presence of areas of low EM wave velocity or high porosity under saturated conditions, causing velocity pull-down areas and apparent sag features in the reflection record. This study shows that GPR can be a useful tool for improving understanding of the petrophysical properties of highly heterogeneous systems such as karst aquifers, and thus may assist with the development of more accurate groundwater flow models, such as those used for restoration efforts in the Everglades.

  6. Characterization of the porosity distribution in the upper part of the karst Biscayne aquifer using common offset ground penetrating radar, Everglades National Park, Florida

    Science.gov (United States)

    Mountain, Gregory S.; Cunningham, Kevin J.; Comas, Xavier

    2014-01-01

    the direct porosity values from the whole-core samples confirms the ability of GPR common offset surveys to provide rapid characterization of porosity variability in the Biscayne aquifer.The common offset survey method has several advantages: (1) improved time efficiency in comparison to other GPR acquisition modes such as common midpoints; and (2) enhanced lateral continuity of porosity estimates, particularly when compared to porosity measurements on 1-D samples such as rock cores. The results also support the presence of areas of low EM wave velocity or high porosity under saturated conditions, causing velocity pull-down areas and apparent sag features in the reflection record. This study shows that GPR can be a useful tool for improving understanding of the petrophysical properties of highly heterogeneous systems such as karst aquifers, and thus may assist with the development of more accurate groundwater flow models, such as those used for restoration efforts in the Everglades.

  7. Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

    Science.gov (United States)

    Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

    2015-03-01

    With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and

  8. Open innovation

    DEFF Research Database (Denmark)

    Bogers, Marcel; Chesbrough, Henry; Moedas, Carlos

    2018-01-01

    Open innovation is now a widely used concept in academia, business, and policy making. This article describes the state of open innovation at the intersection of research, practice, and policy. It discusses some key trends (e.g., digital transformation), challenges (e.g., uncertainty......), and potential solutions (e.g., EU funding programs) in the context of open innovation and innovation policy. With this background, the authors introduce select papers published in this Special Section of California Management Review that were originally presented at the second annual World Open Innovation...

  9. Creating Open Source Conversation

    Science.gov (United States)

    Sheehan, Kate

    2009-01-01

    Darien Library, where the author serves as head of knowledge and learning services, launched a new website on September 1, 2008. The website is built with Drupal, an open source content management system (CMS). In this article, the author describes how she and her colleagues overhauled the library's website to provide an open source content…

  10. Pro OpenSSH

    CERN Document Server

    Stahnke, Michael

    2006-01-01

    SSH, acronym for Secure Socket Shell, is for users and administrators wishing to establish secure communication between disparate networks. 'Pro OpenSSH', authored by two Fortune 100 system administrators, provides readers with a highly practical reference for configuring and deploying OpenSSH in their own environment.

  11. Open nanoporous morphologies from polymeric blends by carbon dioxide foaming

    NARCIS (Netherlands)

    Krause, B.; Diekmann, K.; van der Vegt, N.F.A.; Wessling, Matthias

    2002-01-01

    We report the formation of open nanoporous polymer films composed of homogeneous polysulfone/polyimide blends. Porosity is introduced by expansion of carbon dioxide-saturated films at elevated temperatures. To interpret details of the porous morphologies in terms of the experimental conditions

  12. The Effects of Temperature and Pressure on the Porosity Evolution of Flechtinger Sandstone

    Science.gov (United States)

    Hassanzadegan, Alireza; Blöcher, Guido; Milsch, Harald; Urpi, Luca; Zimmermann, Günter

    2014-03-01

    A porosity change influences the transport properties and the elastic moduli of rock while circulating water in a geothermal reservoir. The static and dynamic elastic moduli can be derived from the slope of stress-strain curves and velocity measurements, respectively. Consequently, the acoustic velocities were measured while performing hydrostatic drained tests. The effect of temperature on static and dynamic elastic moduli and porosity variations of Flechtinger sandstone was investigated in a wide range of confining pressure from 2 to 55 MPa. The experiments were carried out in a conventional triaxial system whereas the pore pressure remained constant, confining pressure was cycled, and temperature was increased step wise (25, 60, 90, 120, and 140 °C). The porosity variation was calculated by employing two different theories: poroelasticity and crack closure. The porosity variation and crack porosity were determined by the first derivative of stress-strain curves and the integral of the second derivative of stress-strain curves, respectively. The crack porosity analysis confirms the creation of new cracks at high temperatures. The porosity variation was increasing with an increase in temperature at low effective pressures and was decreasing with a rise in temperature at high effective pressures. Both compressional and shear wave velocities were increasing with increasing pressure due to progressive crack closure. Furthermore, the thermomechanical behavior of Flechtinger sandstone was characterized by an inversion effect where the sign of the temperature derivative of the drained bulk modulus changes.

  13. Examining the influence of heterogeneous porosity fields on conservative solute transport

    Science.gov (United States)

    Hu, B.X.; Meerschaert, M.M.; Barrash, W.; Hyndman, D.W.; He, C.; Li, X.; Guo, Laodong

    2009-01-01

    It is widely recognized that groundwater flow and solute transport in natural media are largely controlled by heterogeneities. In the last three decades, many studies have examined the effects of heterogeneous hydraulic conductivity fields on flow and transport processes, but there has been much less attention to the influence of heterogeneous porosity fields. In this study, we use porosity and particle size measurements from boreholes at the Boise Hydrogeophysical Research Site (BHRS) to evaluate the importance of characterizing the spatial structure of porosity and grain size data for solute transport modeling. Then we develop synthetic hydraulic conductivity fields based on relatively simple measurements of porosity from borehole logs and grain size distributions from core samples to examine and compare the characteristics of tracer transport through these fields with and without inclusion of porosity heterogeneity. In particular, we develop horizontal 2D realizations based on data from one of the less heterogeneous units at the BHRS to examine effects where spatial variations in hydraulic parameters are not large. The results indicate that the distributions of porosity and the derived hydraulic conductivity in the study unit resemble fractal normal and lognormal fields respectively. We numerically simulate solute transport in stochastic fields and find that spatial variations in porosity have significant effects on the spread of an injected tracer plume including a significant delay in simulated tracer concentration histories.

  14. Increased cortical porosity and reduced cortical thickness of the proximal femur are associated with nonvertebral fracture independent of Fracture Risk Assessment Tool and Garvan estimates in postmenopausal women.

    Science.gov (United States)

    Kral, Rita; Osima, Marit; Borgen, Tove T; Vestgaard, Roald; Richardsen, Elin; Bjørnerem, Åshild

    2017-01-01

    The Fracture Risk Assessment Tool (FRAX) and Garvan Calculator have improved the individual prediction of fracture risk. However, additional bone measurements that might enhance the predictive ability of these tools are the subject of research. There is increasing interest in cortical parameters, especially cortical porosity. Neither FRAX nor Garvan include measurements of cortical architecture, important for bone strength, and providing independent information beyond the conventional approaches. We tested the hypothesis that cortical parameters are associated with fracture risk, independent of FRAX and Garvan estimates. This nested case-control study included 211 postmenopausal women aged 54-94 years with nonvertebral fractures, and 232 controls from the Tromsø Study in Norway. We assessed FRAX and Garvan 10-year risk estimates for fragility fracture, and quantified femoral subtrochanteric cortical porosity, thickness, and area from computed tomography images using StrAx1.0 software. Per standard deviation higher cortical porosity, thinner cortices, and smaller cortical area, the odds ratio (95% confidence interval) for fracture was 1.71 (1.38-2.11), 1.79 (1.44-2.23), and 1.52 (1.19-1.95), respectively. Cortical porosity and thickness, but not area, remained associated with fracture when adjusted for FRAX and Garvan estimates. Adding cortical porosity and thickness to FRAX or Garvan resulted in greater area under the receiver operating characteristic curves. When using cortical porosity (>80th percentile) or cortical thickness (20%), 45.5% and 42.7% of fracture cases were identified, respectively. Using the same cutoffs for cortical porosity or thickness combined with Garvan (threshold >25%), 51.2% and 48.3% were identified, respectively. Specificity for all combinations ranged from 81.0-83.6%. Measurement of cortical porosity or thickness identified 20.4% and 17.5% additional fracture cases that, were unidentified using FRAX alone, and 16.6% and 13.7% fracture

  15. Increased cortical porosity and reduced cortical thickness of the proximal femur are associated with nonvertebral fracture independent of Fracture Risk Assessment Tool and Garvan estimates in postmenopausal women.

    Directory of Open Access Journals (Sweden)

    Rita Kral

    Full Text Available The Fracture Risk Assessment Tool (FRAX and Garvan Calculator have improved the individual prediction of fracture risk. However, additional bone measurements that might enhance the predictive ability of these tools are the subject of research. There is increasing interest in cortical parameters, especially cortical porosity. Neither FRAX nor Garvan include measurements of cortical architecture, important for bone strength, and providing independent information beyond the conventional approaches. We tested the hypothesis that cortical parameters are associated with fracture risk, independent of FRAX and Garvan estimates. This nested case-control study included 211 postmenopausal women aged 54-94 years with nonvertebral fractures, and 232 controls from the Tromsø Study in Norway. We assessed FRAX and Garvan 10-year risk estimates for fragility fracture, and quantified femoral subtrochanteric cortical porosity, thickness, and area from computed tomography images using StrAx1.0 software. Per standard deviation higher cortical porosity, thinner cortices, and smaller cortical area, the odds ratio (95% confidence interval for fracture was 1.71 (1.38-2.11, 1.79 (1.44-2.23, and 1.52 (1.19-1.95, respectively. Cortical porosity and thickness, but not area, remained associated with fracture when adjusted for FRAX and Garvan estimates. Adding cortical porosity and thickness to FRAX or Garvan resulted in greater area under the receiver operating characteristic curves. When using cortical porosity (>80th percentile or cortical thickness (20%, 45.5% and 42.7% of fracture cases were identified, respectively. Using the same cutoffs for cortical porosity or thickness combined with Garvan (threshold >25%, 51.2% and 48.3% were identified, respectively. Specificity for all combinations ranged from 81.0-83.6%. Measurement of cortical porosity or thickness identified 20.4% and 17.5% additional fracture cases that, were unidentified using FRAX alone, and 16.6% and 13

  16. Wave propagation speeds and source term influences in single and integral porosity shallow water equations

    Directory of Open Access Journals (Sweden)

    Ilhan Özgen

    2017-10-01

    Full Text Available In urban flood modeling, so-called porosity shallow water equations (PSWEs, which conceptually account for unresolved structures, e.g., buildings, are a promising approach to addressing high CPU times associated with state-of-the-art explicit numerical methods. The PSWE can be formulated with a single porosity term, referred to as the single porosity shallow water model (SP model, which accounts for both the reduced storage in the cell and the reduced conveyance, or with two porosity terms: one accounting for the reduced storage in the cell and another accounting for the reduced conveyance. The latter form is referred to as an integral or anisotropic porosity shallow water model (AP model. The aim of this study was to analyze the differences in wave propagation speeds of the SP model and the AP model and the implications of numerical model results. First, augmented Roe-type solutions were used to assess the influence of the source terms appearing in both models. It is shown that different source terms have different influences on the stability of the models. Second, four computational test cases were presented and the numerical models were compared. It is observed in the eigenvalue-based analysis as well as in the computational test cases that the models converge if the conveyance porosity in the AP model is close to the storage porosity. If the porosity values differ significantly, the AP model yields different wave propagation speeds and numerical fluxes from those of the BP model. In this study, the ratio between the conveyance and storage porosities was determined to be the most significant parameter.

  17. Inclusions, Porosity, and Fatigue of AlSi10Mg Parts Produced by Selective Laser Melting

    Science.gov (United States)

    Tang, Ming

    dendrite arm spacings in metal powder particles of different diameters were measured and also agree with literature correlations, showing the expected increase in secondary dendrite arm spacing with increasing particle diameter. It is well-known that the fatigue behavior of cast aluminum alloy parts is largely determined by the internal defects, particularly pores and inclusions, such as oxides. This study shows that such imperfections are also present in AlSi10Mg parts produced by SLM, and serve as sites for failure initiation. The effect of hatch spacing and building orientation on tensile and fatigue properties was tested. Similar defects were found both on polished cross-sections and on fracture surfaces. The results imply that the oxide-driven pores dominate the fatigue resistance of the samples in this work. The larger oxide particles which are associated with the crack initiation likely form by oxidation of metal vapor during part manufacture. Residual porosity in parts produced by SLM mainly results from lack-of-fusion, entrapped gas, pores left in powder, evaporation of elements, and collapse of key-holes. Lack-of-fusion porosity is caused by the the insufficient overlap of melt pools in powder bed fusion and is particularly detrimental to fatigue performance due to the stress concentration at the sharp edges of the pores. The third part of this work deals with predicting lack-of-fusion porosity quantitatively by a geometrically-based model and designing processing parameters for build rate improvement without introducing porosity. The inputs into the simulation are hatch spacing, layer thickness, melt-pool cross-sectional area, and hatch rotation angle. Comparison with several data sets from the literature shows that the simulations correctly predict process conditions at which lack-of-fusion porosity becomes apparent, as well as the rate at which porosity increases with changes in process conditions such as beam speed, layer thickness, and hatch spacing

  18. Open hardware for open science

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    Inspired by the open source software movement, the Open Hardware Repository was created to enable hardware developers to share the results of their R&D activities. The recently published CERN Open Hardware Licence offers the legal framework to support this knowledge and technology exchange.   Two years ago, a group of electronics designers led by Javier Serrano, a CERN engineer, working in experimental physics laboratories created the Open Hardware Repository (OHR). This project was initiated in order to facilitate the exchange of hardware designs across the community in line with the ideals of “open science”. The main objectives include avoiding duplication of effort by sharing results across different teams that might be working on the same need. “For hardware developers, the advantages of open hardware are numerous. For example, it is a great learning tool for technologies some developers would not otherwise master, and it avoids unnecessary work if someone ha...

  19. Dual control of flow field heterogeneity and immobile porosity on non‐Fickian transport in Berea sandstone

    National Research Council Canada - National Science Library

    Gjetvaj, Filip; Russian, Anna; Gouze, Philippe; Dentz, Marco

    2015-01-01

    ...) and diffusion in the microporous phase (immobile domain) where the effective diffusion coefficient is calculated from the measured local porosity using a phenomenological model that includes a porosity threshold ( ϕ θ...

  20. Open Access

    Science.gov (United States)

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder…

  1. Permeability, porosity and compressive strength of self-compacting concrete

    Directory of Open Access Journals (Sweden)

    Valcuende, M.O.

    2005-12-01

    Full Text Available Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive strength and pore size distribution showed that self-compacting concrete has lower capillary porosity than traditional concrete, which would explain its greater resistance to water penetration. Such concrete likewise reached higher strength values, except where large proportions of lime powder with low sand equivalents were used in its manufacture, when lower strength was recorded. Lastly, the depth of water penetration and compressive strength were found to be linearly correlated. That correlation was seen to depend, in turn, on the type of concrete, since for any given strength level, self-compacting concrete was less permeable than the traditional material.

    En este trabajo experimental se estudia la penetración de agua en hormigones autocompactables, analizando al mismo tiempo su estructura porosa, pues gran parte de los procesos de deterioro que afectan a la durabilidad de las estructuras están condicionados por estos dos aspectos. Para ello se han fabricado dos tipos de hormigones, uno autocompactable y otro tradicional vibrado, con diferentes relaciones A/C y distintos tipos de cemento. Tras determinar la permeabilidad al agua bajo presión, la resistencia a compresión y las distribuciones de tamaño de poro, los resultados obtenidos ponen de manifiesto que los hormigones autocompactables presentan menor porosidad capilar que los tradicionales, lo que les confiere mejores prestaciones frente a la penetración de agua. Asimismo, dichos hormigones

  2. Feasibility of optimizing trimetazidine dihydrochloride release from controlled porosity

    Directory of Open Access Journals (Sweden)

    Basant A. Habib

    2014-05-01

    Full Text Available The aim of this study was to develop and optimize Trimetazidine dihydrochloride (TM controlled porosity osmotic pump (CPOP tablets of directly compressed cores. A 23 full factorial design was used to study the influence of three factors namely: PEG400 (10% and 25% based on coating polymer weight, coating level (10% and 20% of tablet core weight and hole diameter (0 “no hole” and 1 mm. Other variables such as tablet cores, coating mixture of ethylcellulose (4% and dibutylphthalate (2% in 95% ethanol and pan coating conditions were kept constant. The responses studied (Yi were cumulative percentage released after 2 h (Q%2h, 6 h (Q%6h, 12 h (Q%12h and regression coefficient of release data fitted to zero order equation (RSQzero, for Y1, Y2, Y3, and Y4, respectively. Polynomial equations were used to study the influence of different factors on each response individually. Response surface methodology and multiple response optimization were used to search for an optimized formula. Response variables for the optimized formula were restricted to 10% ⩽ Y1 ⩽ 20%, 40% ⩽ Y2 ⩽ 60%, 80% ⩽ Y3 ⩽ 100%, and Y4 > 0.9. The statistical analysis of the results revealed that PEG400 had positive effects on Q%2h, Q%6h and Q%12h, hole diameter had positive effects on all responses and coating level had positive effect on Q%6h, Q%12h and negative effect on RSQzero. Full three factor interaction (3FI equations were used for representation of all responses except Q%2h which was represented by reduced (3FI equation. Upon exploring the experimental space, no formula in the tested range could satisfy the required constraints. Thus, direct compression of TM cores was not suitable for formation of CPOP tablets. Preliminary trials of CPOP tablets with wet granulated cores were promising with an intact membrane for 12 h and high RSQzero. Further improvement of these formulations to optimize TM release will be done in further studies.

  3. Openness initiative

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, S.S. [Los Alamos National Lab., NM (United States)

    1995-12-31

    Although antinuclear campaigns seem to be effective, public communication and education efforts on low-level radioactive waste have mixed results. Attempts at public information programs on low-level radioactive waste still focus on influencing public opinion. A question then is: {open_quotes}Is it preferable to have a program focus on public education that will empower individuals to make informed decisions rather than trying to influence them in their decisions?{close_quotes} To address this question, a case study with both quantitative and qualitative data will be used. The Ohio Low-Level Radioactive Waste Education Program has a goal to provide people with information they want/need to make their own decisions. The program initiated its efforts by conducting a statewide survey to determine information needed by people and where they turned for that information. This presentation reports data from the survey and then explores the program development process in which programs were designed and presented using the information. Pre and post data from the programs reveal attitude and knowledge shifts.

  4. Controlling the porosity of powder metallurgy products by a laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Uglov, A.A.; Grebennikov, V.A.; Panaetov, V.G.; Ignatev, M.B.

    1986-08-01

    Experimental results obtained for powder metallurgy products based on nickel, bronze, and molybdenum are used to establish a relationship between the porosity of a material and the parameters of the beam-affected zone and also between the characteristics of a laser erosion plasma. The approach proposed here makes it possible to control the porosity of powder metallurgy alloys in the porosity range 0-60 percent for products based on high-melting powders and in the range 0-25 percent for products based on metals with a melting temperature below 2000 C. 9 references.

  5. Evidence of second order transition induced by the porosity in the thermal conductivity of sintered metals

    Directory of Open Access Journals (Sweden)

    Aïmen E. Gheribi

    2014-07-01

    Full Text Available In this paper, using both experimental data and theoretical modelling, we investigate the degradation of the thermal conductivity of sintered metals due simultaneously to the grain boundary thermal resistance and the porosity. We show that the porosity dependence of the thermal conductivity of sintered material from spherical particle powder, exhibits a critical behaviour associated with a second order phase transition. An analytical model with a single parameter is proposed to describe the critical behaviour of the thermal conductivity of sintered metals versus porosity.

  6. Oxygen plasma treatment of HKUST-1 for porosity retention upon exposure to moisture.

    Science.gov (United States)

    Bae, Jaeyeon; Jung, Jin-Woo; Park, Hyo Yul; Cho, Chang-Hee; Park, Jinhee

    2017-10-26

    Despite their remarkable properties, metal-organic frameworks (MOFs) present vulnerable structures that are sensitive to moisture; therefore, their application to real field situations is challenging. Herein, an O2 plasma technique was introduced as a new method for the activation and protection of porosity in HKUST-1. In an unprecedented manner, O2 plasma-treated HKUST-1 retains its porosity after a long exposure to moisture as compared to pristine HKUST-1. Porosity retention was examined by N2 adsorption/desorption measurements of non-activated HKUST-1 after exposure to moisture.

  7. Open Science

    Directory of Open Access Journals (Sweden)

    Süreyya Çankırı

    2017-10-01

    Full Text Available Science is based on the confirmation of phenomena and events in a continuum. In the development of science; the cumulative progress and effective sharing of information comes to the forefront. Within the scope of science, producing new information requires a social approach. Because science has more participants every day so the meaning and importance of science also becomes different. In this sense, the idea of open science, which is based on open access, open data and open source, continues to mediate the socialization of information as well as the purpose of the rapid spread of scientific research results among scientists. In the editorial section, the approach of open science, which has gained momentum in recent years, is evaluated in the context of information retrieval and interaction.

  8. Numerical simulation of casting processes: coupled mould filling and solidification using VOF and enthalpy-porosity method

    Science.gov (United States)

    Richter, Ole; Turnow, Johann; Kornev, Nikolai; Hassel, Egon

    2017-06-01

    Within the scope of industrial casting applications a numerical model for the simultaneous mould filling and solidification process has been formulated, implemented in a finite volume code and successfully validated using analytical and experimental data. In order to account for the developing of free surface flow and the liquid/solid phase change, respectively, the volume-of-fluid and enthalpy-porosity method have been coupled under a volume averaging framework on a fixed Eulerian grid. The coupled method captures the basic physical effects of a combined mould filling and solidification process and provides a trustful method for comprehensive casting simulations.

  9. Open Government Data Publication Methodology

    National Research Council Canada - National Science Library

    Jan Kucera

    2015-01-01

    .... Open Government Data (OGD) initiatives aim at increasing availability of machine-readable data provided under an open license and therefore these initiatives might facilitate re-use of the government data which in turn might...

  10. Open Source and Open Standards

    NARCIS (Netherlands)

    Koper, Rob

    2006-01-01

    Publication reference: Koper, R. (2008). Open Source and Open Standards. In J. M. Spector, M. Merrill, J. van Merriënboer & M. P. Driscol (Eds.), Handbook of Research on Educational Communications and Technology (3rd ed., pp. 355-368). New York: Routledge.

  11. Dynamical Transition of 4He Crystallization in a Very High Porosity Aerogel

    Science.gov (United States)

    Masumoto, Ryota; Ueno, Ken-Ichi; Matsuda, Hirofumi; Nomura, Ryuji; Okuda, Yuichi

    2011-03-01

    Crystallization of 4He in aerogels of 90 and 96% porosities shows a dynamical phase transition at around 600 mK due to the competition between thermal fluctuation and disorder: crystals grow via creep at high temperatures and via avalanche at low temperatures. In a very high porosity 99.5% aerogel, however, the transition had not been observed in our previous publication (Nomura et al. in Phys. Rev. Lett. 101:175703, 2008). We improved the spatial resolution of the video image and found that the 99.5% aerogel did have the transition at around 200 mK, which is much lower than those of the lower porosities. The avalanche size is significantly smaller in the 99.5% aerogel. The reduction in the transition temperature and avalanche size may be the consequence of weaker disorder for the crystallization in the very high porosity aerogel.

  12. Image Analysis and Estimation of Porosity and Permeability of Arnager Greensand, Upper Cretaceous, Denmark

    DEFF Research Database (Denmark)

    Solymar, Mikael; Fabricius, Ida

    1999-01-01

    Arnager Greensand consists of unconsolidated, poorly sorted fine-grained, glauconitic quartz sand, often silty or clayey, with a few horizons of cemented coarse-grained sand. Samples from the upper part of the Arnager Greensand were used for this study to estimate permeability from microscopic...... images. Backscattered Scanning Electron Microscope images from polished thin-sections were acquired for image analysis with the software PIPPIN(R). Differences in grey levels owing to density differences allowed us to estimate porosity, clay and particle content. The images were simplified into two...... magnification of the image can not resolve the microporosity within the clay fraction, so we suggest that the imaged porosity at 150x magnification is close to the effective porosity for permeability assessment. The Heporosity, however, represents the total porosity of the Arnager Greensand. For permeability...

  13. The formation and evolution of layered structures in porous media: effects of porosity and mechanical dispersion

    NARCIS (Netherlands)

    Schoofs, Stan; Trompert, Ron A.; Hansen, Ulrich

    1999-01-01

    Horizontally layered structures can develop in porous or partially molten environments, such as hydrothermal systems, magmatic intrusions and the early Earth's mantle. The porosity f of these natural environments is typically small. Since dissolved chemical elements unlike heat cannot diffuse

  14. A CFD-Model for prediction of unintended porosities in metal matrix composites

    DEFF Research Database (Denmark)

    Li, Shizhao; Spangenberg, Jon; Hattel, Jesper Henri

    2013-01-01

    This paper presents a numerical method that simulates the flow through the porous corridors of the preform, which in theory enables the prediction of unintended porosities at the end of the process....

  15. Investigation on Porosity and Microhardness of 316L Stainless Steel Fabricated by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Shahir Mohd Yusuf

    2017-02-01

    Full Text Available This study investigates the porosity and microhardness of 316L stainless steel samples fabricated by selective laser melting (SLM. The porosity content was measured using the Archimedes method and the advanced X-ray computed tomography (XCT scan. High densification level (≥99% with a low average porosity content (~0.82% were obtained from the Archimedes method. The highest porosity content in the XCT-scanned sample was ~0.61. However, the pores in the SLM samples for both cases (optical microscopy and XCT were not uniformly distributed. The higher average microhardness values in the SLM samples compared to the wrought manufactured counterpart are attributed to the fine microstructures from the localised melting and rapid solidification rate of the SLM process.

  16. The effects of porosity in friction performance of brake pad using waste tire dust

    Directory of Open Access Journals (Sweden)

    İbrahim Mutlu

    2015-10-01

    Full Text Available Abstract This research is focused on the effect of porosity on the friction-wear properties of automotive brake pads. Waste Tire Dust (WTD was used as a new friction material in brake pads. Newly formulated brake pad materials with five different components have been produced by conventional techniques. In the experimental studies, the change of the friction coefficient, the temperature of the friction surface, the specific wear rate, and the hardness, density and porosity were measured. In addition, the micro-structural characterizations of brake pads are determined using Scanning Electron Microscopy (SEM. The mean coefficient of friction, porosity and specific wear are increased due to a WTD rate increases, on the other hand, hardness and density are decreased. As a result, WTD can be considered as an alternative to revalorize this kind of waste products in the brake pads and the amount of porosity of the brake pad affected the friction coefficient and wear behavior of the pad.

  17. Total and methyl mercury, moisture, and porosity in Lake Michigan surficial sediment

    Data.gov (United States)

    U.S. Environmental Protection Agency — Total and methyl mercury, moisture content (%), and porosity were measured in Lake Michigan sediment by the U.S. Environmental Protection Agency/Office of Research...

  18. Optical method for in situ monitoring of electrospinning process and porosity characterization of microporous membrane

    Science.gov (United States)

    Chen, Chung-Han; Huang, Chieh-Tse; Fuh, Yiin-Kuen

    2017-04-01

    We present an optical-based, rapid method for the in situ porosity measurement of membranes through the electrospinning process. The method was developed by combining an optical method with in situ monitoring of the porosity of the electrospun membranes based on the measured reflected power density. The results showed that the area of bright and dark ratio is consistently proportional to the porosity of the electrospun membranes, which can potentially be used for actual characterization of the membranes. In addition, the effect of different incident angles of a laser beam was performed and compared. The porosity ratio of the electrospun membranes can be empirically evaluated as the determination coefficient R2=0.9945 to 0.9876 can be obtained. The proposed method is successfully demonstrated and validated by the SEM images of the binary method. The potential applications include the in situ monitoring of the electrospinning process for the bioassembly and biomimicking of a human tissue with a great accuracy.

  19. Visualization and prediction of porosity in roller compacted ribbonswith near infrared chemical imaging (NIR-CI)

    DEFF Research Database (Denmark)

    Khorasani, Milad Rouhi; Amigo Rubio, Jose Manuel; Sonnergaard, Jørn

    2015-01-01

    reference methods that ribbons compressed at a higher pressure resulted in a lower mean porosity. Using NIR-CI in combination with multivariate data analysis it was possible to visualize and predict the porosity distribution of the ribbons. This approach is considered important for process monitoring......The porosity of roller compacted ribbon is recognized as an important critical quality attribute which has a huge impact on the final product quality. The purpose of this study was to investigate the use of near-infrared chemical imaging (NIR-CI) for porosity estimation of ribbons produced...... at different roll pressures. Two off-line methods were utilized as reference methods. The relatively fast method (oil absorption) was comparable with the more time-consuming mercury intrusion method (R2 = 0.98). Therefore, the oil method was selected as the reference off line method. It was confirmed by both...

  20. Modeling porosity reductions caused by mineral fouling in continuous-wall permeable reactive barriers.

    Science.gov (United States)

    Li, Lin; Benson, Craig H; Lawson, Elizabeth M

    2006-02-01

    A study was conducted to assess key factors to include when modeling porosity reductions caused by mineral fouling in permeable reactive barriers (PRBs) containing granular zero valent iron. The public domain codes MODFLOW and RT3D were used and a geochemical algorithm was developed for RT3D to simulate geochemical reactions occurring in PRBs. Results of simulations conducted with the model show that the largest porosity reductions occur between the entrance and mid-plane of the PRB as a result of precipitation of carbonate minerals and that smaller porosity reductions occur between the mid-plane and exit face due to precipitation of ferrous hydroxide. These findings are consistent with field and laboratory observations, as well as modeling predictions made by others. Parametric studies were conducted to identify the most important variables to include in a model evaluating porosity reduction. These studies showed that three minerals (CaCO3, FeCO3, and Fe(OH)2 (am)) account for more than 99% of the porosity reductions that were predicted. The porosity reduction is sensitive to influent concentrations of HCO3-, Ca2+, CO3(2-), and dissolved oxygen, the anaerobic iron corrosion rate, and the rates of CaCO3 and FeCO3 formation. The predictions also show that porosity reductions in PRBs can be spatially variable and mineral forming ions penetrate deeper into the PRB as a result of flow heterogeneities, which reflects the balance between the rate of mass transport and geochemical reaction rates. Level of aquifer heterogeneity and the contrast in hydraulic conductivity between the aquifer and PRB are the most important hydraulic variables affecting porosity reduction. Spatial continuity of aquifer hydraulic conductivity is less significant.

  1. Micro-CT analysis of filling ability and porosity of root-end filling materials

    Directory of Open Access Journals (Sweden)

    Mário TANOMARU-FILHO

    2017-12-01

    Full Text Available Abstract Introduction Filling ability of retrograde cavity and porosity are important properties for root-end filling materials and may be evaluated by using microcomputed tomography (micro-CT. Objective To evaluate filling ability and porosity of root-end filling materials using microcomputed tomography (micro-CT. Material and method Cavities with 1 mm internal diameter and 3 mm depth were prepared in bovine dentin sections by using ultrasonic tips (CVD No. 6.1107-6, and filled by Mineral Trioxide Aggregate (MTA; Sealer 26 (S26 and zinc oxide and eugenol cement (ZOE. Before and after filling, cavities were scanned by using micro-CT (SkyScan 1176. Filling and porosity were analyzed by using CTAn software. Filling ability was calculated based on volumetric percentage of the filled cavity. The number and percentage of closed pores were measured throughout entire extension of the filled cavity (total and in each third (cervical, middle and apical, by using bi and tridimensional analyses. The filling data were submitted to ANOVA and Tukey statistical tests, and porosity data to Kruskall-Wallis and Dunn tests, at a 5% significance level. Result S26 and ZOE presented higher filling ability than MTA (p<0.05. S26 showed the highest total porosity (number and percentage (p<0.05. In all thirds after 2D and 3D analyses, porosity was higher for S26 in comparison to MTA and ZOE (p<0.05. Conclusion Although Sealer 26 presented more porosity, the material was associated with a great filling ability. Micro-CT analysis showed no correlation between filling ability and porosity.

  2. Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

    Energy Technology Data Exchange (ETDEWEB)

    B.M. Freifeild

    2001-10-18

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  3. Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing

    Energy Technology Data Exchange (ETDEWEB)

    Freifeld, Barry Mark [Univ. of California, Berkeley, CA (United States)

    2001-12-01

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  4. Effects of compositions of filler, binder and porosity on elastic and fracture properties of nuclear graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kyaw, S.T., E-mail: si.kyaw@nottingham.ac.uk; Sun, W.; Becker, A.A.

    2015-02-15

    Highlights: • Micromechanics based homogenisation method is used for graphite microstructures. • Elastic and fracture properties are estimated based on graphite microstructures. • Fracture behaviours are studied using compact tension simulation. • Fracture behaviours are studied using four point bending simulation. • Flexural strengths were obtained and compared to experimental results from literature. - Abstract: Physical mechanisms at different length scales have to be taken into account while predicting the overall failure of nuclear graphite structures of advanced gas cooled graphite reactors. In this paper, the effect of composition of meso graphite phases and porosity on the aggregate elastic properties is predicted using the Eshelby homogenisation method. Results indicate an overall decrease in elastic modulus with an increase in porosity. Subsequently, the moduli at different porosity levels are used to predict the critical strain energy release rates for crack propagation of graphite, and fracture behaviour is studied using compact tension and four point bending tests. Compared to flexural strength at zero porosity level, significant reduction in strength of up to 80% at 30% porosity level is observed. Evolution of flexural strength due to porosity is also compared against available experimental values of graphite from UK nuclear plants.

  5. Effect of increased strut porosity of calcium phosphate bone graft substitute biomaterials on osteoinduction.

    Science.gov (United States)

    Coathup, Melanie J; Hing, Karin A; Samizadeh, Sorousheh; Chan, Oliver; Fang, Yvette S; Campion, Charlie; Buckland, Thomas; Blunn, Gordon W

    2012-06-01

    The effect of increasing strut porosity on the osteoinductivity of porous calcium phosphate (CaP) and silicate-substituted calcium phosphate (SiCaP) bone substitute materials was investigated in an ovine ectopic model. One to two millimeter-sized granules or block implants with strut porosities of 10, 20, or 30% were inserted into the left and right paraspinalis muscle. At 12 weeks, histological sections were prepared through the center of each implant and bone contact, bone area and implant area quantified. Backscattered scanning electron microscopy (bSEM) was used to visualize bone within small pores in the struts of the scaffolds. Increased bone formation was measured in the SiCaP with 30% strut porosity (5.482% ± 1.546%) when compared with the nonsilicate CaP with the same morphology (1.160% ± 0.502%, p = 0.02), indicating that silicate substitution may increase osteoinduction. Greater bone formation was seen in scaffolds with increased strut porosity. No bone growth was found in any of the SiCaP scaffold with 10% porosity. There was no significant difference between block and granule specimens. Scanning electron microscopy and EDX in combination with histology demonstrated bone formation within pores <5 μm in size. The use of silicate-substituted CaP material with increased strut porosity may further augment repair and regeneration in bony sites. Copyright © 2012 Wiley Periodicals, Inc.

  6. Porosity measurement of solid pharmaceutical dosage forms by gamma-ray transmission

    Energy Technology Data Exchange (ETDEWEB)

    Martins de Oliveira, Jose, E-mail: jose.oliveira@prof.uniso.b [Universidade de Sorocaba, UNISO, Campus Seminario, Caixa Postal 578, Avenue, Dr. Eugenio Salermo, 100, Centro, 18035-430 Sorocaba, SP (Brazil); Andreo Filho, Newton; Vinicius Chaud, Marco; Angiolucci, Tatiana; Aranha, Norberto [Universidade de Sorocaba, UNISO, Campus Seminario, Caixa Postal 578, Avenue, Dr. Eugenio Salermo, 100, Centro, 18035-430 Sorocaba, SP (Brazil); Germano Martins, Antonio Cesar [Universidade Estadual Paulista Julio de Mesquita Filho, UNESP, GAGI, Avenue, 3 de Marco, 511, Alto da Boa Vista, 18087-180 Sorocaba, SP (Brazil)

    2010-12-15

    The aim of the present work is the determination of porosity in tablets by using the gamma-ray transmission technique. Tablet dissolution depends on some inherent characteristics of the manufacturing process, such as compression force, tablet volume, density and porosity, nature of excipients, preparation methods and its physical-chemical properties. Porosity is a measure of empty spaces in a material and can be determined by various techniques. In this paper, we propose the use of a gamma-ray transmission technique to obtain the porosity of experimental formulation of tablets. The results of porosity were compared with those obtained by using conventional methodology (density and mercury intrusion). The experimental setup for gamma-ray transmission consists of a gamma-ray source of {sup 241}Am (photons of 59.6 keV and an activity of 3.7x10{sup 9} Bq), an NaI(Tl) scintillation detector, collimators and a standard gamma-ray spectrometry electronics. Our results suggest that the gamma-ray transmission technique is a powerful tool for non-destructive porosity quantification of solid pharmaceutical forms and presents smaller errors than those obtained with conventional methodologies.

  7. Influence of shrinkage porosity on fatigue performance of iron castings and life estimation method

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2016-01-01

    Full Text Available Shrinkage porosity exists more or less in heavy castings, and it plays an important role in the fatigue behavior of cast materials. In this study, fatigue tests were carried out on the QT400-18 cast iron specimens containing random degrees of shrinkage porosity defect. Experimental results showed that the order of magnitude of life scattered from 103 to 106 cycles when the shrinkage percentage ranged from 0.67% to 5.91%. SEM analyses were carried out on the shrinkage porosity region. The inter-granular discontinuous, micro cracks and inclusions interfered with the fatigue sliding or hindering process. The slip in shrinkage porosity region was not as orderly as the ordinary continuous medium. The shrinkage porosity area on fracture surface (SPAFS and alternating stress intensity factor (ASIF were applied to evaluate the tendency of residual life distribution; their relationship was fitted by negative exponent functions. Based on the intermediate variable of ASIF, a fatigue life prediction model of nodular cast iron containing shrinkage porosity defects was established. The modeling prediction was in agreement with the experimental results.

  8. Study of the effects of stress sensitivity on the permeability and porosity of fractal porous media

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Xiao-Hua, E-mail: xiaohua-tan@163.com; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Fan, Zhou

    2015-10-16

    Flow in porous media under stress is very important in various scientific and engineering fields. It has been shown that stress plays an important role in effect of permeability and porosity of porous media. In this work, novel predictive models for permeability and porosity of porous media considering stress sensitivity are developed based on the fractal theory and mechanics of materials. Every parameter in the proposed models has clear physical meaning. The proposed models are evaluated using previously published data for permeability and porosity measured in various natural materials. The predictions of permeability and porosity show good agreement with those obtained by the available experimental data and illustrate that the proposed models can be used to characterize the flow in porous media under stress accurately. - Highlights: • Predictive models for permeability and porosity of porous media considering stress sensitivity are developed. • The fractal theory and mechanics of materials are used in these models. • The predictions of permeability and porosity show good agreement with those obtained by the available experimental data. • The proposed models can be used to characterize the flow in porous media under stress accurately.

  9. Porosity-dependent nonlinear forced vibration analysis of functionally graded piezoelectric smart material plates

    Science.gov (United States)

    Qing Wang, Yan; Zu, Jean W.

    2017-10-01

    This work investigates the porosity-dependent nonlinear forced vibrations of functionally graded piezoelectric material (FGPM) plates by using both analytical and numerical methods. The FGPM plates contain porosities owing to the technical issues during the preparation of FGPMs. Two types of porosity distribution, namely, even and uneven distribution, are considered. A modified power law model is adopted to describe the material properties of the porous FGPM plates. Using D’Alembert’s principle, the out-of-plane equation of motion is derived by taking into account the Kármán nonlinear geometrical relations. After that, the Galerkin method is used to discretize the equation of motion, resulting in a set of ordinary differential equations with respect to time. These ordinary differential equations are solved analytically by employing the harmonic balance method. The approximate analytical results are verified by using the adaptive step-size fourth-order Runge-Kutta method. By means of the perturbation technique, the stability of approximate analytical solutions is examined. An interesting nonlinear broadband vibration phenomenon is detected in the FGPM plates with porosities. Nonlinear frequency-response characteristics of the present smart structures are investigated for various system parameters including the porosity type, the porosity volume fraction, the electric potential, the external excitation, the damping and the constituent volume fraction. It is found that these parameters have significant effects on the nonlinear vibration characteristics of porous FGPM plates.

  10. Shallow-water models with anisotropic porosity and merging for flood modelling on Cartesian grids

    Science.gov (United States)

    Bruwier, M.; Archambeau, P.; Erpicum, S.; Pirotton, M.; Dewals, B.

    2017-11-01

    Shallow-water models with porosity are used to compute floods at a relatively coarse resolution while accounting indirectly for detailed topographic data through porosity parameters. In many practical applications, these models enable a significant reduction of the computational time while maintaining an acceptable level of accuracy. In this paper, we improve the use of porosity models on Cartesian grids by three original contributions. First, a merging technique is used to handle cells with low porosity values which tend otherwise to seriously hamper computational efficiency. Next, we show that the optimal method for the determination of the porosity parameters depends on the modelling scale, i.e. the grid resolution compared to the characteristic size of obstacles and flow ways. Finally, we investigate the potential benefit of using a different porosity parameter in each term of the shallow-water equations. Five test cases, two of them being original, are used to validate the model and assess each contribution. In particular, we obtained speedup values between 10 and 100 while the errors on water depths remain around few percent.

  11. Porosity Gradient Development Around Karst Features due to Tidal Pumping in Eastern Yucatan Peninsula

    Science.gov (United States)

    Maqueda, A.; Renard, P.

    2016-12-01

    Water exchange between karst features and the porous matrix around them has been observed in karst aquifers by previous research. The exchange is driven by hydraulic head gradients caused by stormwater runoff or sea tides and may cause mineral dissolution. The authors of this work proposed a conceptual model of porosity development under tidal variations of hydraulic head is proposed. Simulations of reactive transport and porosity evolution were conducted to explore the porosity gradient development around a karst feature. Simulations account for petrophysical properties of porous media and groundwater geochemical characteristics. Data used in simulations corresponds to an eogenetic karst aquifer found on the eastern coast of Yucatan Peninsula in Mexico. Simulations include both analytical and numerical solutions of porosity increase caused by mineral dissolution. The estimated rate of porosity development and associated wall retreat (3-30 cm/100 yr) are large enough to develop karst cavities on time periods relevant to karst formation in the study area (10K yr). The analytical solution could be used to assess porosity increase in rock samples and can be also applied to model slow reactions in porous media under flow driven by sinusoidal hydraulic boundary conditions. The results show a possible alternative mechanism of karst cavity development in a high conductive limestone rock matrix aquifer.

  12. Impact of surface porosity and topography on the mechanical behavior of high strength biomedical polymers.

    Science.gov (United States)

    Evans, Nathan T; Irvin, Cameron W; Safranski, David L; Gall, Ken

    2016-06-01

    The ability to control the surface topography of orthopedic implant materials is desired to improve osseointegration but is often at the expense of mechanical performance in load bearing environments. Here we investigate the effects of surface modifications, roughness and porosity, on the mechanical properties of a set of polymers with diverse chemistry and structure. Both roughness and surface porosity resulted in samples with lower strength, failure strain and fatigue life due to stress concentrations at the surface; however, the decrease in ductility and fatigue strength were greater than the decrease in monotonic strength. The fatigue properties of the injection molded polymers did not correlate with yield strength as would be traditionally observed in metals. Rather, the fatigue properties and the capacity to maintain properties with the introduction of surface porosity correlated with the fracture toughness of the polymers. Polymer structure impacted the materials relative capacity to maintain monotonic and cyclic properties in the face of surface texture and porosity. Generally, amorphous polymers with large ratios of upper to lower yield points demonstrated a more significant drop in ductility and fatigue strength with the introduction of porosity compared to crystalline polymers with smaller ratios in their upper to lower yield strength. The latter materials have more effective dissipation mechanisms to minimize the impact of surface porosity on both monotonic and cyclic damage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

    2017-10-01

    The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

  14. The Open Access Divide

    Directory of Open Access Journals (Sweden)

    Jingfeng Xia

    2013-10-01

    Full Text Available This paper is an attempt to review various aspects of the open access divide regarding the difference between those academics who support free sharing of data and scholarly output and those academics who do not. It provides a structured description by adopting the Ws doctrines emphasizing such questions as who, what, when, where and why for information-gathering. Using measurable variables to define a common expression of the open access divide, this study collects aggregated data from existing open access as well as non-open access publications including journal articles and extensive reports. The definition of the open access divide is integrated into the discussion of scholarship on a larger scale.

  15. Innovation with open data : Essential elements of open data ecosystems

    NARCIS (Netherlands)

    Zuiderwijk, A.M.G.; Janssen, M.F.W.H.A.; Davis, C.B.

    2014-01-01

    Open data ecosystems are expected to bring many advantages, such as stimulating citizen participation and innovation. However, scant attention has been given to what constitutes an open data ecosystem. The objective of this paper is to provide an overview of essential elements of open data

  16. Open access

    CERN Document Server

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder consent, and many authors, musicians, filmmakers, and other creators who depend on royalties are understandably unwilling to give their consent. But for 350 years, scholars have written peer-reviewed journal articles for impact, not for money, and are free to consent to open access without losing revenue. In this concise introduction, Peter Suber tells us what open access is and isn't, how it benefits authors and readers of research, how we pay for it, how it avoids copyright problems, how it has moved from the periphery to the mainstream, and what its future may hold. Distilling a decade of Suber's influential writing and thinking about open access, this is the indispe...

  17. Wind Tunnel Investigation of the Effects of Surface Porosity and Vertical Tail Placement on Slender Wing Vortex Flow Aerodynamics at Supersonic Speeds

    Science.gov (United States)

    Erickson, Gary E.

    2007-01-01

    A wind tunnel experiment was conducted in the NASA Langley Research Center (LaRC) Unitary Plan Wind Tunnel (UPWT) to determine the effects of passive surface porosity and vertical tail placement on vortex flow development and interactions about a general research fighter configuration at supersonic speeds. Optical flow measurement and flow visualization techniques were used that featured pressure sensitive paint (PSP), laser vapor screen (LVS), and schlieren, These techniques were combined with conventional electronically-scanned pressure (ESP) and six-component force and moment measurements to quantify and to visualize the effects of flow-through porosity applied to a wing leading edge extension (LEX) and the placement of centerline and twin vertical tails on the vortex-dominated flow field of a 65 cropped delta wing model. Test results were obtained at free-stream Mach numbers of 1.6, 1.8, and 2.1 and a Reynolds number per foot of 2.0 million. LEX porosity promoted a wing vortex-dominated flow field as a result of a diffusion and weakening of the LEX vortex. The redistribution of the vortex-induced suction pressures contributed to large nose-down pitching moment increments but did not significantly affect the vortex-induced lift. The trends associated with LEX porosity were unaffected by vertical tail placement. The centerline tail configuration generally provided more stable rolling moments and yawing moments compared to the twin wing-mounted vertical tails. The strength of a complex system of shock waves between the twin tails was reduced by LEX porosity.

  18. Effect of porosity and tortuosity of electrodes on carbon polymer soft actuators

    Science.gov (United States)

    S, Sunjai Nakshatharan; Punning, Andres; Johanson, Urmas; Aabloo, Alvo

    2018-01-01

    This work presents an electro-mechanical model and simulation of ionic electroactive polymer soft actuators with a porous carbon electrode, polymer membrane, and ionic liquid electrolyte. An attempt is made to understand the effects of specific properties of the porous electrodes such as porosity and tortuosity on the charge dynamics and mechanical performance of the actuator. The model uses porous electrode theory to study the electrochemical response of the system. The mechanical response of the whole laminate is attributed to the evolution of local stresses caused by diffusion of ions (diffusion-induced stresses or chemical stresses). The model indicates that in actuators with porous electrode, the diffusion coefficient of ions, conductivity of the electrodes, and ionic conductivity in both electrodes and separator are altered significantly. In addition, the model leads to an obvious deduction that the ions that are highly active in terms of mobility will dominate the whole system in terms of resulting mechanical deformation direction and rate of deformation. Finally, to validate the model, simulations are conducted using the finite element method, and the outcomes are compared with the experimental data. Significant effort has been put forward to experimentally measure the key parameters essential for the validation of the model. The results show that the model developed is able to well predict the behavior of the actuator, providing a comprehensive understanding of charge dynamics in ionic polymer actuator with porous electrodes.

  19. A review on controlled porosity osmotic pump tablets and its evaluation

    Directory of Open Access Journals (Sweden)

    Chinmaya Keshari Sahoo

    2015-12-01

    Full Text Available Conventional drug delivery system provides an immediate release of drug which does not control the release of the drug and does not maintain effective concentration at target site for a longer period of time. Hence to avoid the shortcomings there is development of various controlled drug delivery systems. Among these osmotic drug delivery system (ODDS utilizes the principle of osmotic pressure and delivers drug dose in an optimized manner to maintain drug concentration within the therapeutic window and minimizes toxic effects. ODDS releases drug at a controlled rate that is independent of the pH and thermodynamics of dissolution medium. The release of drug from ODDS follows zero order kinetics. The release of drug from osmotic system depends upon various formulation factors such as solubility, osmotic pressure of the core components, size of the delivery orifice and nature of the rate controlling membrane. Controlled porosity osmotic pump (CPOP contains drug, osmogens, excipients in core and a coating of semipermeable membrane with water soluble additives. In CPOP water soluble additives dissolve after coming in contact with water, resulting in an in situ formation of a microporous membrane. The present study gives an idea about osmosis, CPOP, components of CPOP and its evaluation.

  20. OpenGrey = nová OpenSIGLE

    OpenAIRE

    Pejšová, Petra

    2012-01-01

    OpenGrey is based on the OpenSIGLE/SIGLE database which contains almost 700 thousand records of grey literature. OpenGrey is a unique repository providing open access to European grey literature references, the result of 25 years of cooperation. As a multidisciplinary database it covers Science, Technology, Biomedical Science, Economics, Social Science and Humanities. This paper presents new search functionality, design and vision. The cooperation with GreyNet on GL conference preprints will ...

  1. Open Access, Open Source and Digital Libraries: A Current Trend in University Libraries around the World

    Science.gov (United States)

    Krishnamurthy, M.

    2008-01-01

    Purpose: The purpose of this paper is to describe the open access and open source movement in the digital library world. Design/methodology/approach: A review of key developments in the open access and open source movement is provided. Findings: Open source software and open access to research findings are of great use to scholars in developing…

  2. Open for entrepreneurship

    DEFF Research Database (Denmark)

    Eftekhari, Nazanin; Bogers, Marcel

    2015-01-01

    This paper explores how an open approach to new venture creation – purposefully managing knowledge flows across the venture's organizational boundary – can be beneficial for start-up entrepreneurs. Our inductive case study, of both failure and success, identifies the key attributes of this open a...... for entrepreneurship and innovation research and practice, providing some attention points for researchers, entrepreneurs, investors and policy makers interested in developing successful new ventures....

  3. Open Education and the Open Science Economy

    Science.gov (United States)

    Peters, Michael A.

    2009-01-01

    Openness as a complex code word for a variety of digital trends and movements has emerged as an alternative mode of "social production" based on the growing and overlapping complexities of open source, open access, open archiving, open publishing, and open science. This paper argues that the openness movement with its reinforcing structure of…

  4. OpenSHS: Open Smart Home Simulator

    Science.gov (United States)

    Alshammari, Nasser; Alshammari, Talal; Sedky, Mohamed; Champion, Justin; Bauer, Carolin

    2017-01-01

    This paper develops a new hybrid, open-source, cross-platform 3D smart home simulator, OpenSHS, for dataset generation. OpenSHS offers an opportunity for researchers in the field of the Internet of Things (IoT) and machine learning to test and evaluate their models. Following a hybrid approach, OpenSHS combines advantages from both interactive and model-based approaches. This approach reduces the time and efforts required to generate simulated smart home datasets. We have designed a replication algorithm for extending and expanding a dataset. A small sample dataset produced, by OpenSHS, can be extended without affecting the logical order of the events. The replication provides a solution for generating large representative smart home datasets. We have built an extensible library of smart devices that facilitates the simulation of current and future smart home environments. Our tool divides the dataset generation process into three distinct phases: first design: the researcher designs the initial virtual environment by building the home, importing smart devices and creating contexts; second, simulation: the participant simulates his/her context-specific events; and third, aggregation: the researcher applies the replication algorithm to generate the final dataset. We conducted a study to assess the ease of use of our tool on the System Usability Scale (SUS). PMID:28468330

  5. OpenSHS: Open Smart Home Simulator.

    Science.gov (United States)

    Alshammari, Nasser; Alshammari, Talal; Sedky, Mohamed; Champion, Justin; Bauer, Carolin

    2017-05-02

    This paper develops a new hybrid, open-source, cross-platform 3D smart home simulator, OpenSHS, for dataset generation. OpenSHS offers an opportunity for researchers in the field of the Internet of Things (IoT) and machine learning to test and evaluate their models. Following a hybrid approach, OpenSHS combines advantages from both interactive and model-based approaches. This approach reduces the time and efforts required to generate simulated smart home datasets. We have designed a replication algorithm for extending and expanding a dataset. A small sample dataset produced, by OpenSHS, can be extended without affecting the logical order of the events. The replication provides a solution for generating large representative smart home datasets. We have built an extensible library of smart devices that facilitates the simulation of current and future smart home environments. Our tool divides the dataset generation process into three distinct phases: first design: the researcher designs the initial virtual environment by building the home, importing smart devices and creating contexts; second, simulation: the participant simulates his/her context-specific events; and third, aggregation: the researcher applies the replication algorithm to generate the final dataset. We conducted a study to assess the ease of use of our tool on the System Usability Scale (SUS).

  6. OpenSHS: Open Smart Home Simulator

    Directory of Open Access Journals (Sweden)

    Nasser Alshammari

    2017-05-01

    Full Text Available This paper develops a new hybrid, open-source, cross-platform 3D smart home simulator, OpenSHS, for dataset generation. OpenSHS offers an opportunity for researchers in the field of the Internet of Things (IoT and machine learning to test and evaluate their models. Following a hybrid approach, OpenSHS combines advantages from both interactive and model-based approaches. This approach reduces the time and efforts required to generate simulated smart home datasets. We have designed a replication algorithm for extending and expanding a dataset. A small sample dataset produced, by OpenSHS, can be extended without affecting the logical order of the events. The replication provides a solution for generating large representative smart home datasets. We have built an extensible library of smart devices that facilitates the simulation of current and future smart home environments. Our tool divides the dataset generation process into three distinct phases: first design: the researcher designs the initial virtual environment by building the home, importing smart devices and creating contexts; second, simulation: the participant simulates his/her context-specific events; and third, aggregation: the researcher applies the replication algorithm to generate the final dataset. We conducted a study to assess the ease of use of our tool on the System Usability Scale (SUS.

  7. Open data

    DEFF Research Database (Denmark)

    Bodum, Lars

    2017-01-01

    Everyone wants open data, but the road towards it can be both difficult and long. Implementation of data portals and ICT solutions for support of the data infrastructure can be initiated from the central government through legislation, regulation and public procurement. This is what you would call...

  8. Open Images

    DEFF Research Database (Denmark)

    Sanderhoff, Merete

    2013-01-01

    Museums around the world hold enormous troves of public domain artworks. In digitized form, they can be powerful tools for research and learning, as well as building blocks, in the hands of students, teachers, scholars, developers, and creative people. By opening up their digitized assets for reuse...

  9. Opening Address

    Science.gov (United States)

    John T. Shannon

    2001-01-01

    I am glad to be here today to help open the symposium on Arkansas' forests. It is gratifying to see so many forestry leaders in attendance. I am particulary pleased to welcome my brother, State Forester from Oklahoma, Roger Davis; and representatives of the State Foresters from Tennessee and Louisiana.

  10. opened capsule

    African Journals Online (AJOL)

    by the opened capsule method is bioequivalent to a proprietary formulation approved by regulatory agencies. In the future, paediatric fixed-drug combination (FDC) antiretroviral formulations will greatly accelerate the roll-out of antiretrovirals to children in rural resource-limited settings. However, no paediatric antiretroviral ...

  11. Open IS

    DEFF Research Database (Denmark)

    Germonprez, Matt; Crowston, Kevin; Avital, Michel

    2013-01-01

    The collective intelligence and collective action of “open” communities have produced a variety of complex knowledge goods and radical social change. The Information Systems (IS) community has invested significant effort into researching open communities and the ecosystems in which they operate, ...

  12. Experimental Investigation of Closed Porosity of Inorganic Solidified Foam Designed to Prevent Coal Fires

    Directory of Open Access Journals (Sweden)

    Yi Lu

    2015-01-01

    Full Text Available In order to overcome the deficiency of the existing fire control technology and control coal spontaneous combustion by sealing air leakages in coal mines, inorganic solidified foam (ISF with high closed porosity was developed. The effect of sodium dodecyl sulfate (SDS concentration on the porosity of the foams was investigated. The results showed that the optimized closed porosity of the solidified foam was 38.65 wt.% for an SDS concentration of approximately 7.4×10-3 mol/L. Based on observations of the microstructure of the pore walls after solidification, it was inferred that an equilibrium between the hydration process and the drainage process existed. Therefore, the ISF was improved using three different systems. Gelatin can increase the viscosity of the continuous phase to form a viscoelastic film around the air cells, and the SDS + gelatin system can create a mixed surfactant layer at gas/liquid interfaces. The accelerator (AC accelerates the hydration process and coagulation of the pore walls before the end of drainage. The mixed SDS + gelatin + AC systems produced an ISF with a total porosity of 79.89% and a closed porosity of 66.89%, which verified the proposed stabilization mechanism.

  13. Report on Evaluation, Verification, and Assessment of Porosity Migration Model in Fast Reactor MOX Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Novascone, Stephen Rhead [Idaho National Lab. (INL), Idaho Falls, ID (United States); Peterson, John William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    Abstract This report documents the progress of simulating pore migration in ceramic (UO2 and mixed oxide or MOX) fuel using BISON. The porosity field is treated as a function of space and time whose evolution is governed by a custom convection-diffusion-reaction equation (described here) which is coupled to the heat transfer equation via the temperature field. The porosity is initialized to a constant value at every point in the domain, and as the temperature (and its gradient) are increased by application of a heat source, the pores move up the thermal gradient and accumulate at the center of the fuel in a time-frame that is consistent with observations from experiments. There is an inverse dependence of the fuel’s thermal conductivity on porosity (increasing porosity decreases thermal conductivity, and vice-versa) which is also accounted for, allowing the porosity equation to couple back into the heat transfer equation. Results from an example simulation are shown to demonstrate the new capability.

  14. Calculation of porosity from nuclear magnetic resonance and conventional logs in gas-bearing reservoirs

    Science.gov (United States)

    Xiao, Liang; Mao, Zhi-qiang; Li, Gao-ren; Jin, Yan

    2012-08-01

    The porosity may be overestimated or underestimated when calculated from conventional logs and also underestimated when derived from nuclear magnetic resonance (NMR) logs due to the effect of the lower hydrogen index of natural gas in gas-bearing sandstones. Proceeding from the basic principle of NMR log and the results obtained from a physical rock volume model constructed on the basis of interval transit time logs, a technique of calculating porosity by combining the NMR log with the conventional interval transit time log is proposed. For wells with the NMR log acquired from the MRIL-C tool, this technique is reliable for evaluating the effect of natural gas and obtaining accurate porosity in any borehole. In wells with NMR log acquired from the CMR-Plus tool and with collapsed borehole, the NMR porosity should be first corrected by using the deep lateral resistivity log. Two field examples of tight gas sandstones in the Xujiahe Formation, central Sichuan basin, Southwest China, illustrate that the porosity calculated by using this technique matches the core analyzed results very well. Another field example of conventional gas-bearing reservoir in the Ziniquanzi Formation, southern Junggar basin, Northwest China, verifies that this technique is usable not only in tight gas sandstones, but also in any gas-bearing reservoirs.

  15. Black bear femoral geometry and cortical porosity are not adversely affected by ageing despite annual periods of disuse (hibernation).

    Science.gov (United States)

    McGee, Meghan E; Miller, Danielle L; Auger, Janene; Black, Hal L; Donahue, Seth W

    2007-02-01

    Disuse (i.e. inactivity) causes bone loss, and a recovery period that is 2-3 times longer than the inactive period is usually required to recover lost bone. However, black bears experience annual disuse (hibernation) and remobilization periods that are approximately equal in length, yet bears maintain or increase cortical bone material properties and whole bone mechanical properties with age. In this study, we investigated the architectural properties of bear femurs to determine whether cortical structure is preserved with age in bears. We showed that cross-sectional geometric properties increase with age, but porosity and resorption cavity density do not change with age in skeletally immature male and female bears. These findings suggest that structural properties substantially contribute to increasing whole bone strength with age in bears, particularly during skeletal maturation. Porosity was not different between skeletally immature and mature bears, and showed minimal regional variations between anatomical quadrants and radial positions that were similar in pattern and magnitude between skeletally immature and mature bears. We also found gender dimorphisms in bear cortical bone properties: females have smaller, less porous bones than males. Our results provide further support for the idea that black bears possess a biological mechanism to prevent disuse osteoporosis.

  16. A comparison of discrete versus continuous adjoint states to invert groundwater flow in heterogeneous dual porosity systems

    Science.gov (United States)

    Delay, Frederick; Badri, Hamid; Fahs, Marwan; Ackerer, Philippe

    2017-12-01

    Dual porosity models become increasingly used for simulating groundwater flow at the large scale in fractured porous media. In this context, model inversions with the aim of retrieving the system heterogeneity are frequently faced with huge parameterizations for which descent methods of inversion with the assistance of adjoint state calculations are well suited. We compare the performance of discrete and continuous forms of adjoint states associated with the flow equations in a dual porosity system. The discrete form inherits from previous works by some of the authors, as the continuous form is completely new and here fully differentiated for handling all types of model parameters. Adjoint states assist descent methods by calculating the gradient components of the objective function, these being a key to good convergence of inverse solutions. Our comparison on the basis of synthetic exercises show that both discrete and continuous adjoint states can provide very similar solutions close to reference. For highly heterogeneous systems, the calculation grid of the continuous form cannot be too coarse, otherwise the method may show lack of convergence. This notwithstanding, the continuous adjoint state is the most versatile form as its non-intrusive character allows for plugging an inversion toolbox quasi-independent from the code employed for solving the forward problem.

  17. Characterisation and evaluation of metal-loaded iminodiacetic acid-silica of different porosity for the selective enrichment of phosphopeptides.

    Science.gov (United States)

    Trojer, L; Stecher, G; Feuerstein, I; Lubbad, S; Bonn, G K

    2005-06-24

    Silica particles of different porosity were functionalised with iminodiacetic acid (IDA) and loaded with Fe(III) to yield immobilised metal affinity chromatography stationary phases (Fe(III)-IDA-silica) for phosphopeptide enrichment. The elution step of bound phosphopeptides was optimised with a 32P radioactive labelled peptide by a comprehensive study. Several elution systems, including phosphate buffers of different pH and concentration and ethylenediaminetetraacetic acid solutions were employed. Furthermore the effect of support porosity on elution behaviour was investigated. Under best conditions recoveries higher than 90% were achieved. A solid-phase extraction (SPE) protocol was developed for fractionation of phosphorylated and non-phosphorylated peptides and desalting of the fractions which is essential for subsequent mass spectrometric analysis by the combination of Fe(III)-IDA-silica and C18-silica particles. The pH of the loading buffer was found to be a critical parameter for the efficiency of the SPE protocol. As tryptic digests of alpha-lactalbumin, lysozyme and ribonuclease A mixed with three synthetic phosphopeptides were fractionated, pH 2.5 provided minimal proportion of unspecific bound peptides when comparing the fractions after mu-LC-electrospray ionization MS separation. The effect of a sample derivatisation reaction (methylation) on the efficiency of phosphopeptide enrichment was further investigated. Blocking carboxylate groups by methyl ester formation totally prevented unspecific interaction with the immobilised Fe(III) ions, but generated partially methylated phosphopeptides that increased the complexity of the phosphorylated fraction.

  18. Open Source, Open Access, Open Review, Open Data. Initiativen zu mehr Offenheit in der digitalen Welt

    OpenAIRE

    Herb, Ulrich

    2011-01-01

    The article discusses the principles of openess, open access and open availability of information based on the examples of open access to scientific information, open government data, open geographical data and open source software.

  19. Porous silicon carbide and aluminum oxide with unidirectional open porosity as model target materials for radioisotope beam production

    CERN Document Server

    Czapski, M; Tardivat, C; Stora, T; Bouville, F; Leloup, J; Luis, R Fernandes; Augusto, R Santos

    2013-01-01

    New silicon carbide (SiC) and aluminum oxide (Al2O3) of a tailor-made microstructure were produced using the ice-templating technique, which permits controlled pore formation conditions within the material. These prototypes will serve to verify aging of the new advanced target materials under irradiation with proton beams. Before this, the evaluation of their mechanical integrity was made based on the energy deposition spectra produced by FLORA codes. (C) 2013 Elsevier B.V. All rights reserved.

  20. Prediction and improvement of shrinkage porosity in TiAl based alloy

    Directory of Open Access Journals (Sweden)

    Gao Yong

    2011-02-01

    Full Text Available The present research has developed a novel investment casting process for ingot production of TiAl alloys through forming a small vertical temperature gradient on the mold. The advantage of this process is to guarantee that the castings solidify sequentially from bottom to top. The analysis of numerical simulation and experimental results showed that the shrinkage porosity of Ti-47Al-2Cr-2Nb alloy was significantly improved by forming a vertical temperature gradient of 3 ℃/mm on the mold, while the increase of pouring temperature and pressure on the molten alloys had no apparent effect on the reduction of shrinkage porosity. The critical value of the Niyama criterion that can reliably predict the shrinkage porosity in Ti-47Al-2Cr-2Nb alloy was identified by the comparison of experimental and simulated results.

  1. In silico modeling of structural and porosity properties of additive manufactured implants for regenerative medicine.

    Science.gov (United States)

    Brünler, Ronny; Aibibu, Dilbar; Wöltje, Michael; Anthofer, Anna-Maria; Cherif, Chokri

    2017-07-01

    Additive manufacturing technologies are a promising technology towards patient-specific implants for applications in regenerative medicine. The Net-Shape-Nonwoven technology is used to manufacture structures from short fibers with interconnected pores and large functional surfaces that are predestined for cell adhesion and growth. The present study reports on a modeling approach with a particular focus on the specific structural properties. The overall porosities and mean pore-sizes of the digital models are simulated according to liquid-displacement porosity in a tool implemented in the modeling software. This allows adjusting the process parameters fiber length and fiber diameter to generate biomimetic structures with pore-sizes adapted to the requirements of the tissue that is to be replaced. Modeling the structural and porosity properties of scaffolds and implants leads to an efficient use of the processed biomaterials as the trial-and-error method is avoided. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Permeability, compressibility and porosity of Jurassic shale from the Norwegian-Danish Basin

    DEFF Research Database (Denmark)

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Krogsbøll, Anette

    2014-01-01

    . Porosity measurements obtained using helium porosimetry-mercury immersion (HPMI), mercury injection capillary pressure (MICP) and nuclear magnetic resonance (NMR) techniques on the shale samples show that MICP porosity is 6-10% lower than HPMI or NMR porosity. Compressibility, from uniaxial loading......, and from combined MICP and NMR data. The permeability predicted from Brunauer-Emmett-Teller (BET)-specific surface-area measurements using Kozeny's formulation for these shales, being rich in silt and kaolinite, falls in the same order of magnitude as permeability measured from constant rate of strain (CRS...... studied and compared to samples from Skjold Flank-1in the Central North Sea. Mineralogical analyses based on X-ray diffractometry (XRD) show that onshore shales from the Norwegian-Danish Basin are siltier than offshore shales from the Central Graben. Illite and kaolinite dominate the clay fraction...

  3. Comparison of results from different NDE techniques from ceramic matrix composites with varying porosity levels

    Science.gov (United States)

    Smyth, Imelda; Ojard, Greg; Santhosh, Unni; Ahmad, Jalees; Gowayed, Yasser

    2015-03-01

    Ceramic matrix composites (CMC's) are attractive materials for use in advanced turbine engines. Due to the nature of available processing techniques, however, the amount and distribution of porosity in CMC's can vary greatly. This can be particularly true in parts with complex geometries. It is therefore important to characterize the porosity with non-destructive techniques and understand its effect on properties. A series of CMC samples were fabricated with varying levels of porosity and analyzed with different NDE techniques. The results were categorized and analyzed with respect to ease of interpretation and degree to which they could be quantified and used in models to determine the effects of defects. The results were also correlated with microstructural examination and mechanical properties.

  4. The Production of Porous Hydroxyapatite Scaffolds with Graded Porosity by Sequential Freeze-Casting.

    Science.gov (United States)

    Lee, Hyun; Jang, Tae-Sik; Song, Juha; Kim, Hyoun-Ee; Jung, Hyun-Do

    2017-03-31

    Porous hydroxyapatite (HA) scaffolds with porosity-graded structures were fabricated by sequential freeze-casting. The pore structures, compressive strengths, and biocompatibilities of the fabricated porous HA scaffolds were evaluated. The porosities of the inner and outer layers of the graded HA scaffolds were controlled by adjusting the initial HA contents of the casting slurries. The interface between the dense and porous parts was compact and tightly adherent. The porosity and compressive strengths of the scaffold were controlled by the relative thicknesses of the dense/porous parts. In addition, the porous HA scaffolds showed good biocompatibility in terms of preosteoblast cell attachment and proliferation. The results suggest that porous HA scaffolds with load-bearing parts have potential as bone grafts in hard-tissue engineering.

  5. Pore former induced porosity in LSM/CGO cathodes for electrochemical cells for flue gas purification

    DEFF Research Database (Denmark)

    Skovgaard, M.; Andersen, Kjeld Bøhm; Kammer Hansen, Kent

    2012-01-01

    In this study the effect of the characteristics of polymethyl methacrylate (PMMA) pore formers on the porosity, pore size distribution and the air flow through the prepared lanthanum strontium manganate/gadolinium-doped cerium oxide (LSM/CGO) cathodes was investigated. Porous cathodes were obtained...... and the highest porosity measured was 46.4% with an average pore diameter of 0.98 μm. The air flow through this cathode was measured to 5.8 ml/(min mm2). Also the effect of exposure time to the solvent was tested for the most promising PMMA pore former and it was found that the average pore diameter decreases...... as a result of elongated exposure. Also prolong milling of the LSM powder was found to decrease the porosity of the final cathode and milling time should be highly controlled in order to obtain as porous cathodes as possible....

  6. Secondary carbonate porosity as related to early teritiary depositional facies, Zelten field, Libya

    Energy Technology Data Exchange (ETDEWEB)

    Bebout, D.G.; Pendexter, C.

    1975-04-01

    Production from the Zelten field, Libya, is from the highly porous shelf limestones of the Zelten Member (Main Pay) of the Paleocene and lower Eocene Ruaga Limestone. Fifteen facies are recognized, mapped, and predicted. Seven of the facies comprise the larger part of the Zelten Member. These include miliolid-foraminiferal micrite, argillaceous bryozoan/echinoid micrite, argillaceous-molluscan micrite, coralgal micrite. Discocyclina-foraminiferal calcarenite, foraminiferal calcarenite and micrite, and Discocyclina-foraminiferal micrite. In the Zelten field secondary porosity is recorded as much as 40%; this porosity is related to the original depositional fabric of the sediment and, therefore, is facies controlled. Porosity is highest in the coralgal micrite and Discocyclina-foraminiferal calcarenite, which together form a NW.-SE. trend across the N. part of the field, and in the formaniniferal calcarenite and micrite. (10 refs.)

  7. Analyze of the Possible Causes of Porosity Type Deffects in Aluminium High Pressure Diecast Parts

    Directory of Open Access Journals (Sweden)

    Ferencz Peti

    2011-06-01

    Full Text Available Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mold during the process. Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.Die castings are characterized by a very good surface finish (by casting standards and dimensional consistency.The most common deffect that appear in castings is the porosity type of deffect, which can be gas porosity, shrinkage porosity or leaker.

  8. The influence of the deposition parameters on the porosity of thin alumina films on steel

    Directory of Open Access Journals (Sweden)

    DUSAN KICEVIC

    2004-03-01

    Full Text Available The influence of the deposition parameters on the porosity of thin alumina films electrophoretically deposited on steel from aqueous suspensions was investigated. The effects of the applied voltage, deposition time, suspension temperature and the solid content of the aqueous suspension on the porosity of the obtained alumina films have been determined using optical microscopy coupled with image analysis. It was shown that the lowest film porosity was obtained from a suspension containing 20 wt.% alumina powder at the lowest applied voltage (30 V, for a longer deposition time (10 min using a suspension temperature of 30 ºC. This behavior can be explained by the smaller amount of hydrogen evolved on the cathode during the electrophoretic deposition process.

  9. The Production of Porous Hydroxyapatite Scaffolds with Graded Porosity by Sequential Freeze-Casting

    Directory of Open Access Journals (Sweden)

    Hyun Lee

    2017-03-01

    Full Text Available Porous hydroxyapatite (HA scaffolds with porosity-graded structures were fabricated by sequential freeze-casting. The pore structures, compressive strengths, and biocompatibilities of the fabricated porous HA scaffolds were evaluated. The porosities of the inner and outer layers of the graded HA scaffolds were controlled by adjusting the initial HA contents of the casting slurries. The interface between the dense and porous parts was compact and tightly adherent. The porosity and compressive strengths of the scaffold were controlled by the relative thicknesses of the dense/porous parts. In addition, the porous HA scaffolds showed good biocompatibility in terms of preosteoblast cell attachment and proliferation. The results suggest that porous HA scaffolds with load-bearing parts have potential as bone grafts in hard-tissue engineering.

  10. Open innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2017-01-01

    Interest in open innovation (OI) as a field of research has grown exponentially since the phrase was coined by Chesbrough in his 2003 book, with numerous articles, special issues, books, and conference sessions. Various reviews of the literature have summarized prior work, offered new frameworks,...... is rejected, abandoned, or fails. Finally, we consider how OI can be better linked to prior theoretical research, including topics such as absorptive capacity, user innovation, resources, dynamic capabilities, business models, and the definition of the firm....

  11. Providing Compassion through Flow

    Directory of Open Access Journals (Sweden)

    Lydia Royeen

    2015-07-01

    Full Text Available Meg Kral, MS, OTR/L, CLT, is the cover artist for the Summer 2015 issue of The Open Journal of Occupational Therapy. Her untitled piece of art is an oil painting and is a re-creation of a photograph taken while on vacation. Meg is currently supervisor of outpatient services at Rush University Medical Center. She is lymphedema certified and has a specific interest in breast cancer lymphedema. Art and occupational therapy serve similar purposes for Meg: both provide a sense of flow. She values the outcomes, whether it is a piece of art or improved functional status

  12. Preparation of open-cell metal foams by investment cast

    Directory of Open Access Journals (Sweden)

    Lucai WANG

    2005-02-01

    Full Text Available Metal foams are a new kind of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They can be divided into closed and open cell structures. In this paper the open cell structures, called sponges, were treated. A new technique to manufacture sponges by plaster investment casting was described. Experimental results show that it is essential to make a sound plaster mould by casting plaster slurry into the polyurethane foams and infiltrate the open channels of the baked plaster mold by molten metal. The optimal processes include plaster slurry preparation, plaster mold baking, and molten metal infiltration. The sponge sample with porosity of 97% is presented.

  13. Formation of shrinkage porosity during solidification of steel: Numerical simulation and experimental validation

    Science.gov (United States)

    Riedler, M.; Michelic, S.; Bernhard, C.

    2016-07-01

    The phase transformations in solidification of steel are accompanied by shrinkage and sudden changes in the solubility of alloying elements, resulting in negative side effects as micro- and macrosegregation and the formation of gas and shrinkage porosities. This paper deals with the numerical and experimental simulation of the formation of shrinkage porosity during the solidification of steel. First the physical basics for the mechanism of shrinkage pore formation will be discussed. The main reason for this type of porosity is the restraint of fluid flow in the mushy zone which leads to a pressure drop. The pressure decreases from the dendrite tip to the root. When the pressure falls below a critical value, a pore can form. The second part of the paper deals with different approaches for the prediction of the formation of shrinkage porosity. The most common one according to these models is the usage of a simple criterion function, like the Niyama criterion. For the computation of the porosity criterion the thermal gradient, cooling rate and solidification rate must be known, easily to determine from numerical simulation. More complex simulation tools like ProCAST include higher sophisticated models, which allow further calculations of the shrinkage cavity. Finally, the different approaches will be applied to a benchmark laboratory experiment. The presented results deal with an ingot casting experiment under variation of taper. The dominant influence of mould taper on the formation of shrinkage porosities can both be demonstrated by the lab experiment as well as numerical simulations. These results serve for the optimization of all ingot layouts for lab castings at the Chair of Ferrous Metallurgy.

  14. Effects of porosity on corrosion resistance of Mg alloy foam produced by powder metallurgy technology

    Energy Technology Data Exchange (ETDEWEB)

    Aghion, E., E-mail: egyon@bgu.ac.il; Perez, Y.

    2014-10-15

    Magnesium alloy foams have the potential to serve as structural material for regular light-weight applications as well as for biodegradable scaffold implants. However, their main disadvantage relates to the high reactivity of magnesium and consequently their natural tendency to corrode in regular service conditions and in physiological environments. The present study aims at evaluating the effect of porosity on the corrosion resistance of MRI 201S magnesium alloy foams in 0.9% NaCl solution and in phosphate buffer saline solution as a simulated physiological electrolyte. The magnesium foams were produced by powder metallurgy technology using space-holding particles to control the porosity content. Machined chips were used as raw material for the production of Mg alloy powder by milling process. The microstructure of the foams was examined using optical and scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. The corrosion behavior was evaluated by immersion test and potentiodynamic polarization analysis. The results obtained clearly demonstrate that the porosity has a significant effect on the corrosion resistance of the tested foams. Foams with 14–19% porosity have a corrosion rate of 4–10 mcd and 7–15 mcd in NaCl and phosphate buffer saline solution, respectively, compared to only 0.10 mcd for the same alloy in as cast conditions. This increased corrosion degradation of the Mg foams by more than one order of magnitude compared to the cast alloy may limit their potential application in regular and physiological environments. - Highlights: • Porosity has a detrimental effect on corrosion resistance of MRI 201S Mg foams. • 14–19% porosity increases the corrosion rate by more than one order of magnitude. • Accelerated corrosion limits the use of foams in regular/physiological environments.

  15. Effects of porosity on the fatigue performance of polymethyl methacrylate bone cement: an analytical investigation.

    Science.gov (United States)

    Evans, S L

    2006-01-01

    Porosity has been shown to affect the fatigue life of bone cements, but, although vacuum mixing is widely used to reduce porosity in the clinical setting, results have been mixed and the effects of porosity are not well understood. The aim of this study was to investigate the effects of porosity using stress analysis and fracture mechanics techniques. The stress concentrations arising at voids in test specimens were found using analytical solutions and boundary element methods. The fatigue life of specimens containing voids of various sizes was predicted using fracture mechanics techniques. For spherical voids that do not occupy a significant proportion of the cross-section, the resulting stress concentration is independent of void size and too small to account for the observed crack initiation. Cracks must therefore initiate at additional stress raisers such as radiopacifier particles or additional voids. For large voids, the stress increases as the remaining cross-section of the specimen decreases, and this may account for much of the observed reduction in fatigue strength in hand-mixed cement. Although crack initiation may be largely independent of void size, there is an effect on crack growth rate. Cracks are predicted to grow faster around larger voids, since they remain in the stress concentration around the void for longer. This effect may account for the relationship between porosity and fatigue life that has been observed in samples without large voids. Since porosity appears to affect crack growth more than initiation, it may be less damaging in high-cycle clinical fatigue, which may be predominantly initiation controlled, than in short laboratory tests.

  16. Compressive strength and porosity tests on bovine hydroxyapatite-gelatin-chitosan scaffolds

    Directory of Open Access Journals (Sweden)

    Nadia Kartikasari

    2016-09-01

    Full Text Available Background: Degenerative diseases, aggressive periodontitis, trauma, jaw resection, and congenital abnormalities can cause defects in jaw bone. The surgical procedure for bone reconstruction currently performed is bone regeneration graft (BRG. Unfortunately, this procedure still has many disadvantages. Thus, tissue engineering approach is necessary to be conducted. The main component used in this tissue engineering is scaffolds. Scaffolds used in bone regeneration is expected to have appropriate characteristics with bone, such as high porosity and swelling ratio, low degradation rates, and good mechanical properties. For those reasons, this research used scaffolds made from bovine hydroxyapatite (BHA, gelatin (GEL, and chitosan (K/BHA-GEL-K as one of biomaterial candidates for bone regeneration. Purpose: This study aimed to determine compressive strength value and porosity size of BHA-GEL-K scaffolds. Method: Compressive strength of BHA-GEL-K scaffolds was tested using autograph with speed 10 mm/ min with a load cell compress machine of 100 kN. Compressive strength was calculated by force divided to surface area. Porosity test was measured using SEM. Scaffold were coated with Pb and Au, then the porosity size is calculated with SEM at 100x magnification. Result: BHA-GEL-K scaffolds had a mean compressive strength value of 174.29 kPa and a porosity size of 31.62 + 147.06 lm. Conclusion: It can be concluded that BHA-GEL-K scaffolds has a good compressive strength, but not yet resemble real bone mass, while porosity of BHA-GEL-K scaffold is appropriate for bone tissue regeneration application.

  17. Fractal dimensions and porosities of Zoogloea ramigera and Saccharomyces cerevisae aggregates.

    Science.gov (United States)

    Logan, B E; Wilkinson, D B

    1991-08-05

    The fractal nature microbial aggregates is a function of the type of microorganism and mixing conditions used to develop aggregates. We determined fractal dimensions from length-projected area (D(2)) and length-number scaling (D(3)) relationships. Aggregates of Zoogloea ramigera developed in rotating test tubes were both surface and mass fractals, with fractal dimensions of D(2) = 1.69 +/- 0.11 and D(3)= 1.79 +/- 0.28 (+/-standard deviation), respectively. When we grew this bacteria in a bench-top fermentor, aggregates maintained their surface fractal characteristics (D(2) = 1.78 +/- 0.11) but lost their mass fractal characteristics (D(3) = 2.99 +/- 0.36). Yeast aggregates (Saccharomyces cerevisae) grown in rotating tests tubes had higher average fractal dimensions than bacterial aggregates grown under physically identical conditions, and were also considered fractal (D(2) = 1.92 +/- 0.08 and D(3) = 2.66 +/- 0.34). Aggregates porosity can be expressed in term of a fractal dimensions, but average porosities are higher than expected. The porosities of yeast aggregates (0.9250-0.9966) were similar to porosities of bacterial aggregates (0.9250-0.9966) cultured under the same physical conditions, although bacterial aggregates developed in the reactor had higher average porosities (0.9857-0.9980). These results suggest that that scaling relationships based on fractal geometry may be more useful than equations derived from Euclidean geometry for quantifying the effects of different fluid mechanical environments on aggregates morphology and characteristics such as density, porosity, and projected surface area.

  18. Trade-off between root porosity and mechanical strength in species with different types of aerenchyma.

    Science.gov (United States)

    Striker, G G; Insausti, P; Grimoldi, A A; Vega, A S

    2007-05-01

    The objective of this work was to study the existence of a trade-off between aerenchyma formation and root mechanical strength. To this end, relationships among root anatomical traits and mechanical properties were analysed in plant species with contrasting root structural types: Paspalidium geminatum (graminaceous type), Cyperus eragrostis (cyperaceous type), Rumex crispus (Rumex type) and Plantago lanceolata (Apium type). Variations in anatomical traits and mechanical strength were assessed as a function of root diameter by exposing plants to 0, 7, 15 and 30 d of control and flooded conditions. For each species, the proportion of root cortex was positively associated with the increment of root diameter, contributing to the increase in root porosity under both control and flooded conditions. Moreover, cell lysis produced an additional increase in root porosity in most species under flooded conditions (except R. crispus). Both structural types that presented a uniseriate layer (epidermis) to cope with compression (Rumex and Apium types) were progressively weakened as root porosity increased. This effect was significant even when the increment of root porosity was solely because of increased root diameter (R. crispus), as when both processes (root diameter and cell lysis) added porosity to the roots (P. lanceolata). Conversely, structural types that presented a multiseriate ring of cells in the outer cortex (graminaceous and cyperaceous types) maintained mechanical strength over the whole range of porosity, in spite of lysogenic processes registered in the inner cortex. In conclusion, our study demonstrates a strong trade-off between aerenchyma formation and mechanical strength in root structural types that lacked a multiseriate ring of tissue for mechanical protection in the outer cortex. The results suggest that this ring of tissue plays a significant role in maintaining the mechanical strength of roots when flooding induces the generation of additional aerenchyma

  19. Push-pull tests for estimating effective porosity: expanded analytical solution and in situ application

    Science.gov (United States)

    Paradis, Charles J.; McKay, Larry D.; Perfect, Edmund; Istok, Jonathan D.; Hazen, Terry C.

    2017-10-01

    The analytical solution describing the one-dimensional displacement of the center of mass of a tracer during an injection, drift, and extraction test (push-pull test) was expanded to account for displacement during the injection phase. The solution was expanded to improve the in situ estimation of effective porosity. The truncated equation assumed displacement during the injection phase was negligible, which may theoretically lead to an underestimation of the true value of effective porosity. To experimentally compare the expanded and truncated equations, single-well push-pull tests were conducted across six test wells located in a shallow, unconfined aquifer comprised of unconsolidated and heterogeneous silty and clayey fill materials. The push-pull tests were conducted by injection of bromide tracer, followed by a non-pumping period, and subsequent extraction of groundwater. The values of effective porosity from the expanded equation (0.6-5.0%) were substantially greater than from the truncated equation (0.1-1.3%). The expanded and truncated equations were compared to data from previous push-pull studies in the literature and demonstrated that displacement during the injection phase may or may not be negligible, depending on the aquifer properties and the push-pull test parameters. The results presented here also demonstrated the spatial variability of effective porosity within a relatively small study site can be substantial, and the error-propagated uncertainty of effective porosity can be mitigated to a reasonable level (< ± 0.5%). The tests presented here are also the first that the authors are aware of that estimate, in situ, the effective porosity of fine-grained fill material.

  20. Open traffic : A toolbox for traffic research

    NARCIS (Netherlands)

    Tamminga, G.F.; Knoppers, P.; Van Lint, J.W.C.

    2014-01-01

    Open Traffic is an open source software project that provides a transport modeling software environment. While most transport model packages offer ready-to-use modules for end-users, Open Traffic provides open access to a modelling environment for the (further) development of methods and algorithms

  1. Porosity effect of 3D-printed polycaprolactone membranes on calvarial defect model for guided bone regeneration.

    Science.gov (United States)

    Shim, Jin-Hyung; Jeong, Jae-Hyang; Won, Joo-Yun; Bae, Ji-Hyeon; Ahn, Geunseon; Jeon, Hojun; Yun, Won-Soo; Bae, Eun-Bin; Choi, Jae-Won; Lee, So-Hyoun; Jeong, Chang-Mo; Chung, Ho Yun; Huh, Jung-Bo

    2017-12-15

    The appropriate porosity and pore size of barrier membranes were associated with the transportation of biomolecules required for new bone formation and angiogenesis. In this study, we fabricated three-dimensional (3D)-printed resorbable polycaprolactone (PCL) membranes with different porosities (30%, 50%, and 70%) to evaluate the effective pore size for guided bone regeneration (GBR) membranes. To analyze mechanical properties and cytocompatibility, PCL membranes prepared using extrusion-based 3D printing technology were compared in dry and wet conditions and tested in vitro. The proliferation rates and pattern of fibroblasts and preosteoblasts on PCL membranes with different porosities were determined using a cell counting kit-8 assay and scanning electron microscopy. PCL membrane porosity did not affect cell proliferation, but osteogenic differentiation and mechanical properties were increased with lower porosity (30%) on day 14 (p membranes with lower porosity (p GBR membranes.

  2. Prevention of Porosities in Insert-type Electron Beam Welding for Nodular Cast Iron

    OpenAIRE

    Fumio, SHIBATA; SEIICHI, ANDO; College of Science and Technology, Nihon University; College of Industrial Technology, Nihon University

    1983-01-01

    This paper reports about investigations in regard to the influences of the welding conditions mainly on porosities in insert-type electron beam welding for 50 Kgf/mm^2 class nodular cast iron (plate thickness: 6, 12, 18mm) with austenitic stainless steel SUS304 (thickness: 0.5 mm) as insert metal. Bead appearances, shape of fusion zone, porosities, state of weld cracks, and tensile test of weld joint have been carefully observed under the influences of welding conditions, that is, pretreatmen...

  3. Porosity Dependence of Piezoelectric Properties for Porous Potassium Niobate System Ceramics

    Science.gov (United States)

    Wada, S.; Mase, Y.; Shimizu, S.; Maeda, K.; Fujii, I.; Nakashima, K.; Pulpan, P.; Miyajima, N.

    2011-10-01

    Porous potassium niobate (KNbO3, KN) system ceramics were prepared by a conventional sintering method using carbon black (CB) nanoparticles. First, KN nanoparticles with a size of 100 nm was mixed with CB nanoparticles and binder using ball milling with ethanol. The mixture was dried, and pressed into pellets using uniaxial pressing. After binder burnout, these ceramics was sintered in air. Their piezoelectric properties were measured and discussed a relationship between porosity and piezoelectric properties. As the results, with increasing porosity, piezoelectric g33 constant increased significantly, which suggested that porous ceramics were effective for stress sensor application.

  4. Study of the influence of agricultural waste on the porosity of clay brick

    Directory of Open Access Journals (Sweden)

    Chelouah Nasser

    2015-02-01

    Full Text Available This paper deals with the influence of two organic residues on the porosity of clay bricks. The insulation capacity of the brick increases with increasing the porosity. Combustible organic additions are often used to form pores. The formation of the more homogenous porous structure is favourably impacted by using the crushed rough olive stones containing oil. Plasticity, bulk density and mechanical properties were studied. The additions of organic residues have proved successful to form pores while maintaining the mechanical properties in the limits of the Algerian norms.

  5. Nano-porosity in GaSb induced by swift heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kluth, P., E-mail: patrick.kluth@anu.edu.au; Schnohr, C. S.; Giulian, R.; Araujo, L. L.; Lei, W.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Ridgway, M. C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Sullivan, J.; Weed, R. [ARC Centre for Antimatter-Matter Studies, AMPL, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Li, W.; Ewing, R. C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States)

    2014-01-13

    Nano-porous structures form in GaSb after ion irradiation with 185 MeV Au ions. The porous layer formation is governed by the dominant electronic energy loss at this energy regime. The porous layer morphology differs significantly from that previously reported for low-energy, ion-irradiated GaSb. Prior to the onset of porosity, positron annihilation lifetime spectroscopy indicates the formation of small vacancy clusters in single ion impacts, while transmission electron microscopy reveals fragmentation of the GaSb into nanocrystallites embedded in an amorphous matrix. Following this fragmentation process, macroscopic porosity forms, presumably within the amorphous phase.

  6. Determination of bleb capsule porosity with an experimental glaucoma drainage device and measurement system.

    Science.gov (United States)

    Ross, Craig; Pandav, Surinder Singh; Li, Yu Qin; Nguyen, Dan Q; Beirne, Stephen; Wallace, Gordon G; Shaarawy, Tarek; Crowston, Jonathan G; Coote, Michael

    2015-05-01

    Control of intraocular pressure after implantation of a glaucoma drainage device (GDD) depends on the porosity of the capsule that forms around the plate of the GDD. To compare capsular porosity after insertion of 2 different GDDs using a novel implant and measurement system. We performed an experimental interventional study at an eye research facility in a tertiary eye care center. Testing was performed on 22 adult New Zealand white rabbits that received the experimental GDD or an existing GDD. A new experimental GDD, the Center for Eye Research Australia (CERA) implant, was created using computer-aided design and a 3-dimensional printer. The CERA GDDs were implanted in the eyes of rabbits randomized into 1 of the following 3 groups: with no connection to the anterior chamber (n = 7), with connection to the anterior chamber for 1 week (n = 5), and with connection to the anterior chamber for 4 weeks (n = 5). In a control group (n = 5), a pediatric GDD was implanted without connection to the anterior chamber. We measured the capsular porosity using a pressure-gated picoliter pump at a driving pressure of 12 mm Hg. The animals were killed humanely for histologic study. Porosity of the fibrous capsule around the implant. We found no difference in mean (SEM) capsular porosity between the CERA (3.39 [0.76; 95% CI, 1.43-5.48] µL/min) and pediatric (4.52 [0.52; 95% CI, 3.19-5.95] µL/min) GDDs (P = .28, unpaired t test) at 4 weeks without aqueous exposure. Mean (SEM) capsular porosity of CERA GDDs connected to the anterior chamber at 1 week was 2.46 (0.36; 95% CI, 1.55-3.44) µL/min but decreased to 0.67 (0.07; 95% CI, 0.49-0.86) µL/min at 4 weeks (P = .001, unpaired t test). Our experimental method permits direct measurement of capsular porosity of an in situ GDD. In a comparison between an experimental (CERA) and an existing GDD, no differences were identified in capsular porosity or histologic reaction between the implants. These results suggest that the CERA GDD

  7. Effects of Passive Porosity on Interacting Vortex Flows at Supersonic Speeds

    Science.gov (United States)

    Erickson, Gary E.

    2000-01-01

    A wind tunnel experiment was conducted in the NASA Langley Research Center (LaRC) Unitary Plan Wind Tunnel (UPW7) to determine the effects of passive surface porosity on vortex flow interactions about a general research fighter configuration at supersonic speeds. Optical flow measurement and flow visualization techniques were used and included pressure-sensitive paint (PSP), schlieren, and laser vapor screen (LVS). These techniques were combined with force and moment and conventional electronically-scanned pressure (ESP) measurements to quantify and to visualize the effects flow-through porosity applied to a wing leading-edge extension (LEX) mounted to a 65 deg cropped delta wing model.

  8. Porosity and Permeability Evolution Accompanying Hot fluid Injection into Diatomite, SUPRI TR-123

    Energy Technology Data Exchange (ETDEWEB)

    Diabira, I.; Castanier, L.M.; Kovscek, A.R.

    2001-04-19

    An experimental study of silica dissolution was performed to probe the evolution of permeability and porosity in siliceous diatomite during hot fluid injection such as water or steam flooding. Two competing mechanisms were identified. Silica solubility in water at elevated temperature causes rock dissolution thereby increasing permeability; however, the rock is mechanically weak leading to compressing of the solid matrix during injection. Permeability and porosity can decrease at the onset of fluid flow. A laboratory flow apparatus was designed and built to examine these processes in diatomite core samples.

  9. Preparation of high porosity xerogels by chemical surface modification.

    Science.gov (United States)

    Deshpande, Ravindra; Smith, Douglas M.; Brinker, C. Jeffrey

    1996-01-01

    This invention provides an extremely porous xerogel dried at vacuum-to-below supercritical pressures but having the properties of aerogels which are typically dried at supercritical pressures. This is done by reacting the internal pore surface of the wet gel with organic substances in order to change the contact angle of the fluid meniscus in the pores during drying. Shrinkage of the gel (which is normally prevented by use of high autoclave pressures, such that the pore fluid is at temperature and pressure above its critical values) is avoided even at vacuum or ambient pressures.

  10. Adhesive Layer Thickness and Porosity Criteria for Bonded Joints

    Science.gov (United States)

    1982-12-01

    ALUMINUM REPRESENTING ADHESIVE SHEAR FAILURES JADHERENDS 20 3 SPECIAL DAMMIN4G DURING FABRICATIONABOVE~~ 0 010I 80 IN ALUMINUM DOUBE LP 6R9!1AOHE RE NOS 16...the problem than to provide quality assurance r- *standards. TENSION IN BAG SQUEEZES OUT )II ADHESIVE SPLICE OR DOUBLER WIRE A BAG, SPLICE OR DOUBE ...MOOULUSE C POISSON S RATIO (10 JOINT GEOMETRY ... .. . - - -- T WVY PEEL STRESS DISTRIBU rION £ A A & A A £ V THROUGH THICKNESS (Ec ACCOUNTS FOR

  11. Dual-porosity analysis of conservative tracer testing in saturated volcanic rocks at Yucca Mountain in Nye County, Nevada

    Science.gov (United States)

    Fahy, M.F.

    1997-01-01

    A radially convergent conservative tracer injection test was conducted between boreholes UE-25 #2 and UE-25 c #3 of the C-hole complex at Yucca Mountain to determine effective porosity and longitudinal dispersivity. Approximately 47% of the tracer mass was recovered and a dual-porosity analytical model replicates the breakthrough curve. Fractured-rock analyses focus on the fracture-porosity and geometry as the controlling factors in transport.

  12. Investigation on Formation Mechanism of Irregular Shape Porosity in Hypoeutectic Aluminum Alloy by X-Ray Real Time Observation

    Science.gov (United States)

    Liao, Hengcheng; Zhao, Lei; Wu, Yuna; Fan, Ran; Wang, Qigui; Pan, Ye

    2012-08-01

    The formation mechanism of irregular shape porosity in hypoeutectic aluminum silicon alloy (A356) was investigated by X-ray real time observation on porosity evolution during solidification and re-melting. Porosity in the hypoeutectic aluminum A356 alloy with high hydrogen content (>0.3 mL/100 g Al) first forms in the liquid as small spherical gas bubbles, then expands along with the pressure drop in the mushy zone due to shrinkage and lack of feeding, and finally deforms into irregular morphology by the impingement of aluminum dendrite network. Degassing is a key to eliminate porosity in aluminum alloy castings.

  13. Porosity study of synthetic sandstones by non-destructive nuclear techniques; Estudo da porosidade de arenitos sinteticos por tecnicas nucleares nao-destrutivas

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Leonardo Carmezini

    2008-07-01

    In this paper, nuclear techniques have been used to describe structural characteristics of ceramic samples. These samples were produced to serve as simulates of sandstones and their mainly component was silica (SiO{sub 2}). Three sets of these samples with different characteristics were analyzed with the gamma ray transmission and the X-ray microtomography. They had the function to describe parameters as porosity point to point and total average porosity, for the transmission case, and 2D sections average porosity, total average porosity and size porous distribution for microtomography, as well as to investigate possible irregularities in bulk sample. The experimental set up for the Gamma Ray Transmission technique consisted of: a 2'' x 2'' crystal NaI(Tl) detector, an {sup 241}Am radioactive source (59.54 keV, 100 mCi), an automatic micrometric table for the sample XZ movement and standard gamma spectrometry electronics. Lead collimators with 2 mm diameter were placed on the source way out and on the detector entrance. The microtomographic measurements were done with a Skyscan system, model 1172, with a X -ray tube with 20 - 100 kV of voltage range and a CCD camera. Employing gamma ray transmission method was possible to obtain overall porosity values from 25.8 to 34.0 % and from 24.8 to 29.2 % for samples with parallelepiped and cylinder shape, respectively, for ceramic I set; from 58.5 to 61.0 % and from 57.1 to 61.7 % for the same geometric shape of ceramic II set. The samples analyzed by the microtomography achieved resolutions of 1.73 {mu}m, 0.64 {mu}m and 1.28 {mu}m for samples of ceramic set I, II and III, respectively. This methodology provided average total porosity values from 26.6 to 29.4 %, from 48.4 to 51.0 % and from 28.2 to 30.6 % to I, II and III ceramic sets, respectively. The porous size profiles of each ceramic sample were also measured. (author)

  14. Study of the porosity of synthetic sandstones by nondestructive nuclear techniques; Estudo da porosidade de arenitos sinteticos por tecnicas nucleares nao destrutivas

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Leonardo Carmezini

    2008-07-01

    In this paper, nuclear techniques have been used to describe structural characteristics of ceramic samples. These samples were produced to serve as simulates of sandstones and their mainly component was silica (SiO{sub 2}). Three sets of these samples with different characteristics were analyzed with the gamma ray transmission and the X-ray microtomography. They had the function to describe parameters as porosity point to point and total average porosity, for the transmission case, and 2D sections average porosity, total average porosity and size porous distribution for microtomography, as well as to investigate possible irregularities in bulk sample. The experimental set up for the gamma ray transmission technique consisted of: a 2 x 2 crystal NaI(Tl) detector, an {sup 241}Am radioactive source (59.54 keV, 100 mCi), an automatic micrometric table for the sample XZ movement and standard gamma spectrometry electronics. Lead collimators with 2 mm diameter were placed on the source way out and on the detector entrance. The microtomographic measurements were done with a Skyscan system, model 1172, with a X-ray tube with 20-100 kV of voltage range and a CCD camera. Employing gamma ray transmission method was possible to obtain overall porosity values from 25.8 to 34.0 % and from 24.8 to 29.2 % for samples with parallelepiped and cylinder shape, respectively, for ceramic I set; from 58.5 to 61.0 % and from 57.1 to 61.7 % for the same geometric shape of ceramic II set. The samples analyzed by the microtomography achieved resolutions of 1.73 {mu}m, 0.64 {mu}m and 1.28 {mu}m for samples of ceramic set I, II and III, respectively. This methodology provided average total porosity values from 26.6 to 29.4 %, from 48.4 to 51.0 % and from 28.2 to 30.6 % to I, II and III ceramic sets, respectively. The porous size profiles of each ceramic sample were also measured. (author)

  15. Digital Scholarship and Open Access

    Science.gov (United States)

    Losoff, Barbara; Pence, Harry E.

    2010-01-01

    Open access publications provide scholars with unrestricted access to the "conversation" that is the basis for the advancement of knowledge. The large number of open access journals, archives, and depositories already in existence demonstrates the technical and economic viability of providing unrestricted access to the literature that is the…

  16. Open University

    CERN Multimedia

    Pentz,M

    1975-01-01

    Michel Pentz est née en Afrique du Sud et venu au Cern en 1957 comme physicien et président de l'associaion du personnel. Il est également fondateur du mouvement Antiapartheid de Genève et a participé à la fondation de l'Open University en Grande-Bretagne. Il nous parle des contextes pédagogiques, culturels et nationaux dans lesquels la méthode peut s'appliquer.

  17. Timed bisimulation and open maps

    DEFF Research Database (Denmark)

    Hune, Thomas; Nielsen, Mogens

    1998-01-01

    Open maps have been used for defining bisimulations for a range of models, but none of these have modelled real-time. We define a category of timed transition systems, and use the general framework of open maps to obtain a notion of bisimulation. We show this to be equivalent to the standard notion...... of timed bisimulation. Thus the abstract results from the theory of open maps apply, e.g. the existence of canonical models and characteristic logics. Here, we provide an alternative proof of decidability of bisimulation for finite timed transition systems in terms of open maps, and illustrate the use...... of open maps in presenting bisimulations....

  18. Discrete-dual-porosity model for electric current flow in fractured rock

    Science.gov (United States)

    Roubinet, Delphine; Irving, James

    2014-02-01

    The identification of fractures and the characterization of their properties are of critical importance in a wide variety of research fields and applications. To this end, geophysical methods are of significant interest as they can provide information regarding the spatial distribution of a number of subsurface physical properties in a rapid and noninvasive manner. Electrical resistivity surveying, in particular, has been shown in several previous investigations to exhibit sensitivity to the presence of fractures, suggesting that geoelectrical experiments may contain important information regarding how fractures are distributed and connected in the subsurface. However, a lack of suitable numerical modeling tools for electric current flow in fractured media has prevented a detailed and systematic exploration of this concept. To address this issue, we present a novel discrete-dual-porosity modeling approach that is specifically tailored to the electrical resistivity problem. With our approach, an analytical formulation for fracture-matrix current flow exchange at the fracture scale is integrated into a discrete-fracture-network model, which is then combined with a block-scale finite-volume representation of the rock matrix. Our methodology allows for low-cost and accurate simulation of electric current flow through both the fractures and matrix, and is readily applicable to complex fracture networks at relatively large scales. Although formulated here in two dimensions, this work represents an important first step toward investigating the effect of fracture-network characteristics on bulk electrical properties, as well as toward the simulation of geoelectrical survey data in realistic fractured-rock environments.

  19. Consistency and bicharacteristic analysis of integral porosity shallow water models. Explaining model oversensitivity to mesh design

    Science.gov (United States)

    Guinot, Vincent

    2017-09-01

    The Integral Porosity and Dual Integral Porosity two-dimensional shallow water models have been proposed recently as efficient upscaled models for urban floods. Very little is known so far about their consistency and wave propagation properties. Simple numerical experiments show that both models are unusually sensitive to the computational grid. In the present paper, a two-dimensional consistency and characteristic analysis is carried out for these two models. The following results are obtained: (i) the models are almost insensitive to grid design when the porosity is isotropic, (ii) anisotropic porosity fields induce an artificial polarization of the mass/momentum fluxes along preferential directions when triangular meshes are used and (iii) extra first-order derivatives appear in the governing equations when regular, quadrangular cells are used. The hyperbolic system is thus mesh-dependent, and with it the wave propagation properties of the model solutions. Criteria are derived to make the solution less mesh-dependent, but it is not certain that these criteria can be satisfied at all computational points when real-world situations are dealt with.

  20. Biot's coefficient as an indicator of strength and porosity reduction: Calcareous sediments from Kerguelen Plateau

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Borre, Mai Kirstine; Fabricius, Ida Lykke

    2010-01-01

    β to fall, even when porosity remains constant. Biot's coefficient correlates with strength-indicating properties: compressional and shear modulus, oedometer modulus, yield strength, strain from direct loading and creep strain. Our data indicate that β may be used for predicting the diagenetic...

  1. Crystalline niobia with tailored porosity as support for cobalt catalysts for the Fischer–Tropsch synthesis

    NARCIS (Netherlands)

    Hernández Mejía, C.; den Otter, J. H.; Weber, J. L.; de Jong, K. P.

    2017-01-01

    Structure and catalytic performance of niobia-supported cobalt catalysts were studied based on crystal phase, porosity and cobalt loading. Crystalline niobia as support proved to be a prerequisite to obtain highly active and selective Co/niobia Fischer–Tropsch catalysts, whereas amorphous niobia

  2. Passively Aerated Composting of Straw-Rich Pig Manure : Effect of Compost Bed Porosity

    NARCIS (Netherlands)

    Veeken, A.H.M.; Wilde, de V.; Hamelers, H.V.M.

    2002-01-01

    Straw-rich manure from organic pig farming systems can be composted in passively aerated systems as the high application of straw results in a compost bed with good structure and porosity. The passively aerated composting process was simulated in one-dimensional reactors of 2 m3 for straw-rich

  3. Self-supported ceramic substrates with directional porosity by mold freeze casting

    DEFF Research Database (Denmark)

    Gurauskis, Jonas; Graves, Christopher R.; Moreno, R.

    2016-01-01

    in a mold and applying directional freeze casting. Use of optimized suspension, cryoprotector additive and mold proved to deliver defect free ceramic films with high dimensional control. Microstructure analysis demonstrated the formation of desirable aligned porosity at macro-structural scale and resulted...

  4. Air-Filled porosity and permeability relationships during solid-waste fermentation

    NARCIS (Netherlands)

    Richard, T.L.; Veeken, A.H.M.; Wilde, de V.; Hamelers, H.V.M.

    2004-01-01

    An experimental apparatus was constructed to measure the structural parameters of organic porous media, i.,e. mechanical strength, air-filled porosity, air permeability, and the Ergun particle size. These parameters are critical to the engineering of aerobic bioconversion systems and were measured

  5. Effect of porosity and pore morphology on the low-frequency ...

    Indian Academy of Sciences (India)

    It has been observed that the real and the imaginary parts of the complex dielectric permittivity, for the specimens, depend not only on the porosity but also on the pore size distribution and pore morphology significantly. Unlike normal Debye relaxation process, where the loss tangent vis-à-vis the imaginary part of the ...

  6. Impedance Spectroscopic Characterisation of Porosity in 3D Cell Culture Scaffolds with Different Channel Networks

    DEFF Research Database (Denmark)

    Canali, Chiara; Mohanty, Soumyaranjan; Heiskanen, Arto

    2015-01-01

    We present the application of electrochemical impedance spectroscopy (EIS) as a method for discriminating between different polydimethylsiloxane (PDMS) scaffolds for three-dimensional (3D) cell cultures. The validity of EIS characterisation for scaffolds having different degree of porosity...... serve as means of single-frequency measurements for fast scaffold characterization combined with in vitro monitoring of 3D cell cultures....

  7. Effect of recasting of nickel-chromium alloy on its porosity

    Directory of Open Access Journals (Sweden)

    Jayant Palaskar

    2010-01-01

    Full Text Available Statement of Problem: As per the review of literature very few studies have been carried on recasting of dental casting alloy and in particlular its effect on occurrence of porosities. Purpose of Study: This study was designed to find out occurrence of porosities in new alloy and recasted alloy using a scanning electron microscope. Materials and Methods: Different percentage combinations of new and once casted alloy were used to produce twenty five samples. Castings obtained from new alloy were used as control group. All the samples were scanned under scanning electron mocroscope and photographs were taken from three specific sites for comparison. Results: There is no significant difference in occurrence of porosities in casting obtained by using new alloy and recasted alloy. Conclusion: With in the limitations of the study it is conducted that the prorosities will not be affected by recasting of neckel-chromium alloy. Clinical Implication: Porosities in dental casting alloy can alter physical and mechanical properties of the mental which inturn may lead to failure of crown and bridge, and also cast partial denture prosthesis.

  8. Correlation between Shear Wave Velocity and Porosity in Porous Solids and Rocks

    Directory of Open Access Journals (Sweden)

    J. Kováčik

    2013-01-01

    Full Text Available The shear wave velocity dependence on porosity was modelled using percolation theory model for the shear modulus porosity dependence. The obtained model is not a power law dependence (no simple scaling with porosity, but a more complex equation. Control parameters of this equation are shear wave velocity of bulk solid, percolation threshold of the material and the characteristic power law exponent for shear modulus porosity dependence. This model is suitable for all porous materials, mortars and porous rocks filled with liquid or gas. In the case of pores filled with gas the model can be further simplified: The term for the ratio of the gas density to the density of solid material can be omitted in the denominator (the ratio is usually in the range of (10−4, 10−3 for all solids. This simplified equation was then tested on the experimental data set for porous ZnO filled with air. Due to lack of reasonable data the scientists are encouraged to test the validity of proposed model using their experimental data.

  9. Easily recoverable titanosilicate zeolite beads with hierarchical porosity: Preparation and application as oxidation catalysts

    NARCIS (Netherlands)

    Cheng, Wenjing; Jiang, Yanqiu; Xu, Xianzhu; Wang, Yan; Lin, Kaifeng; Pescarmona, Paolo P.

    2016-01-01

    Titanosilicate zeolite beads with hierarchical porosity and 0.2-0.5 mm diameter (HPB-TS-1) have been synthesized from a titanosilicate solution, employing a porous anion-exchange resin as shape- and structure-directing template. The characterization results showed the existence of crystalline TS-1

  10. High throughput vegetable oil-in-water emulsification with a high porosity micro-engineered membrane

    NARCIS (Netherlands)

    Wagdare, N.A.; Marcelis, A.T.M.; Ho, O.B.; Boom, R.M.; Rijn, van C.J.M.

    2010-01-01

    Emulsification with high porosity micro-engineered membranes leads to stable emulsions with a low droplet span when, besides a surfactant in the continuous phase, an additional, suitable surfactant is used in the dispersed phase. This surfactant should exhibit relatively fast adsorption dynamics,

  11. Effect of spherical porosity on co-fired dense/porous zirconia bi-layers cambering

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Marani, Debora; Kiebach, Wolff-Ragnar

    2018-01-01

    behavior during sintering by thermo-mechanical analysis, using cyclic loading dilatometry. The camber development of the bi-layers is measured by in-situ optical dilatometry. In accordance with the model prediction, cambering can be controlled tuning the porosity while achieving a synergetic effect between...

  12. Modifying the Hierarchical Porosity of SBA-15 via Mild-Detemplation Followed by Secondary Treatments

    NARCIS (Netherlands)

    Zhang, Zheng; Melian-Cabrera, Ignacio

    2014-01-01

    Fenton-chemistry-based detemplation combined with secondary treatments offers options to tune the hierarchical porosity of SBA-15. This approach has been studied on a series of SBA-15 mesophases and has been compared to the conventional calcination. The as-synthesized and detemplated materials were

  13. Porous polymer networks: synthesis, porosity, and applications in gas storage/separation

    NARCIS (Netherlands)

    Lu, W.; Yuan, D.; Zhao, D.; Schilling, C.I.; Plietzsch, O.; Muller, T.; Bräse, S.; Guenther, J.; Blümel, J.; Krishna, R.; Li, Z.; Zhou, H.C.

    2010-01-01

    Three porous polymer networks (PPNs) have been synthesized by the homocoupling of tetrahedral monomers. Like other hyper-cross-linked polymer networks, these materials are insoluble in conventional solvents and exhibit high thermal and chemical stability. Their porosity was confirmed by N2 sorption

  14. Effect of ultrasonic excitation on the porosity of glass ionomer cement: a scanning electron microscope evaluation.

    Science.gov (United States)

    Coldebella, Cármen Regina; Santos-Pinto, Lourdes; Zuanon, Angela Cristina Cilense

    2011-01-01

    Ultrasonic excitation (US) was applied to glass ionomer cement (GIC) during early set time to increase the advantageous properties of this material. The aim of this in vitro study was to assess the inner porosity of GIC after US. A total of 16 specimens, for each material, were prepared from high-viscosity GIC Fuji IX GP, Ketac Molar, and Ketac Molar Easymix. Half of these specimens (n = 8) received 30 s of US during the initial cement setting. After completion of the material setting, specimens were fractured and observed by scanning electronic microscopy to quantitatively assay porosity inside the material using Image J software. Statistical data analysis revealed that US reduced the porosity for all tested materials (P ≤ 0.05). The following reductions (expressed in percentages) were achieved: Fuji IX--from 3.9% to 2.8%; Ketac Molar Easy Mix--from 4.4% to 2.6%, and Ketac Molar--from 2.4% to 1.6%. Under the tested conditions, US was an effective method for porosity reduction inside the material. © 2010 Wiley-Liss, Inc.

  15. On Ionization and Porosity in MHD Couette Flow of a Two ...

    African Journals Online (AJOL)

    The effect of ionization and porosity on the field structure of two-component plasma is studied. The flow is initiated by a relative motion of two horizontal flat plates in the presence of a uniformly applied magnetic field. A fully developed, viscous, incompressible flow with no convection current applies and the profile together ...

  16. Investigation on the Accuracy of CT Porosity Analysis of Additive Manufactured Metallic Parts

    NARCIS (Netherlands)

    Zanini, Filippo; Hermanek, Petr; Rathore, Jitendra; Wits, Wessel W; Carmignato, Simone

    2015-01-01

    Additive manufacturing (AM) is emerging as an important manufacturing sector, due to its almost unlimited design freedom, the capability to produce personalized parts and the efficient material use. A reliable knowledge about material porosity of manufactured parts is crucial for optimizing AM

  17. Porosity prediction of I-field in the Niger delta area using well-log ...

    African Journals Online (AJOL)

    -statistical analysis and seismic attributes to determine porosity values in order to overcome the problem of multiple well drilling. The study area, I-field, is located between latitudes 4.7950oN and 4.8186oN, longitudes 6.9595oE and 6.9800oE.

  18. Investigation of the effect of temperature, porosity, and microstructure on the strength of meteoric and planetary materials

    Science.gov (United States)

    Chen, Laura; Swift, Damian; Herbold, Eric; Tear, Gareth; Zick, Tom; Brugman, Ben; Remington, Tane; Bruck Syal, Megan; Strang, Eric

    2017-06-01

    Laser-driven shock experiments have been performed at the Trident Laser facility at Los Alamos National Laboratory and at the Janus laser at the Lawrence Livermore National Laboratory, investigating Fe, Fe-Ni metals, silicates, Fe-rich meteorites and chondrites under high strain-rate, dynamic loading at a range of initial temperatures. Material strength as a function of temperature, porosity, and microstructure is studied to reveal the kinetics attributed to the deformation of each material. Post-shock recovery analyses including x-ray diffraction, SEM/EBSD, and x-ray tomography help characterize microstructural and mesoscale changes in the constituent materials. The ultimate goal is to account for varying material and microstructure within meteors subjected to shock wave induced thermal gradients to predict how a bolide will break-up and ablate under high strain-rate loading, such as atmospheric entry, as well as provide reliable models for asteroid deflection methods.

  19. Open-Ended Evolution

    DEFF Research Database (Denmark)

    Taylor, Tim; Bedau, Mark A.; Channon, Alastair

    2016-01-01

    This report describes the First Workshop on Open-Ended Evolution: Recent Progress and Future Milestones (OEE1), held during the ECAL 2015 conference at the University of York, U.K., in July 2015. We briefly summarise the content of the talks and discussions and the workshop, and provide links...

  20. Studying Exchange with Less-mobile Porosity at the Laboratory Scale: Experimentation and Multiphysics Simulations

    Science.gov (United States)

    MahmoodPoorDehkordy, F.; House, B.; Briggs, M. A.; Singha, K.; Day-Lewis, F. D.; Zarnetske, J. P.; Lane, J. W., Jr.

    2016-12-01

    Exchange between mobile and less-mobile porosity zones in heterogeneous porous media can impact redox zonation and contaminant transport in the hyporheic zone and near-stream aquifer. Field and laboratory-scale experiments have shown that pairing geoeletrical methods with fluid sampling enables the quantification of paired more- and less-mobile porosity, including less-mobile zones dominated by advection or diffusion. Specifically, geoelectrical methods are sensitive to solute tracer dynamics throughout the total porosity of the porous medium whereas fluid sampling is more sensitive to the more-mobile domain. Simultaneous measurements of the combination of bulk and fluid conductivity improves quantification of less-mobile solute dynamics compared to traditional fluid-only sampling approaches that rely on fluid conductivity alone. Upon injection of a tracer into the porous medium, exchange of solute between more- and less-mobile zones causes a lag (hysteresis) between the change in the bulk conductivity of the sample and fluid conductivity in the more-mobile zone. In this study, we used controlled laboratory column experiments, combined with numerical modeling, to explore the hysteretic relationship between bulk conductivity and fluid conductivity in sandy sediments with embedded cobbles. These column results inform the design and interpretation of field experiments in glacial kettle ponds with similar bed material. A plastic disk placed within the sand column normal to flow direction was used to represent the effect of embedded cobbles. A hydraulic shadow, or dead zone, formed downgradient of the plastic disk and causing previously well-connected sand pores to function as less-mobile porosity within the column. Experiments were run at varied pressure gradients to assess the response of natural fluid flux perturbations on less-mobile dead zones dominated by advective exchange. The experimental configuration was also modeled in COMSOL Multiphysics to simulate coupled

  1. Evolution of Anode Porosity under Air Oxidation: The Unveiling of the Active Pore Size

    Directory of Open Access Journals (Sweden)

    Francois Chevarin

    2017-03-01

    Full Text Available The carbon anode, used in aluminum electrolysis (Hall–Héroult process, is over-consumed by air oxidation and carboxy-reaction (with CO2. Several anode features may affect this over-consumption, such as impurity content, graphitization level and anode porosity features (e.g., porosity volume fraction or pore size distribution. The two first parameters are basically related to the quality of raw materials and coke calcination conditions. Anode porosity is, however, greatly affected by anode manufacturing conditions, and is possible to be modified, to some extent, by adjusting the anode recipe and the processing parameters. This work aims to investigate the effect of anode porosity on its air reactivity. Baked anode samples were prepared in laboratory scale and then crushed into powder form (−4760 + 4000 µm. The recipe for anode preparation was similar to a typical industrial recipe, except that in the lab scale no butt particles were used in the recipe. Anode particles were then gasified at six different conversion levels (0, 5, 15, 25, 35 and 50 wt % under air at 525 °C. The porosity was characterized in several pore size ranges, measured by nitrogen adsorption and mercury intrusion (0.0014–0.020, 0.002–0.025, 0.025–0.100, 0.1–40.0 and superior at 40 µm. The volume variation of each pore range, as a function of carbon conversion, was assessed and used to determine the size of the most active pores for air oxidation. The most active pore size was found to be the pores inferior at 40 µm before 15 wt % of gasification and pores superior at 40 µm between 15 and 50 wt % of carbon conversion. Limitation of pore size range could be used as an additional guideline, along with other targets such as high homogeneity and density, to set the optimum anode manufacturing parameters.

  2. Reliability of a method for evaluating porosity in denture base resins.

    Science.gov (United States)

    Pero, Ana Carolina; Marra, Juliê; Paleari, André Gustavo; de Souza, Raphael Freitas; Ruvolo-Filho, Adhemar; Compagnoni, Marco Antonio

    2011-06-01

    The method of porosity analysis by water absorption has been carried out by the storage of the specimens in pure water, but it does not exclude the potential plasticising effect of the water generating unreal values of porosity. The present study evaluated the reliability of this method of porosity analysis in polymethylmethacrylate denture base resins by the determination of the most satisfactory solution for storage (S), where the plasticising effect was excluded. Two specimen shapes (rectangular and maxillary denture base) and two denture base resins, water bath-polymerised (Classico) and microwave-polymerised (Acron MC) were used. Saturated anhydrous calcium chloride solutions (25%, 50%, 75%) and distilled water were used for specimen storage. Sorption isotherms were used to determine S. Porosity factor (PF) and diffusion coefficient (D) were calculated within S and for the groups stored in distilled water. anova and Tukey tests were performed to identify significant differences in PF results and Kruskal-Wallis test and Dunn multiple comparison post hoc test, for D results (α=0.05). For Acron MC denture base shape, FP results were 0.24% (S 50%) and 1.37% (distilled water); for rectangular shape FP was 0.35% (S 75%) and 0.19% (distilled water). For Classico denture base shape, FP results were 0.54% (S 75%) and 1.21% (distilled water); for rectangular shape FP was 0.7% (S 50%) and 1.32% (distilled water). FP results were similar in S and distilled water only for Acron MC rectangular shape (p>0.05). D results in distilled water were statistically higher than S for all groups. The results of the study suggest that an adequate solution for storing specimens must be used to measure porosity by water absorption, based on excluding the plasticising effect. © 2009 The Gerodontology Society and John Wiley & Sons A/S.

  3. Porosity determination from 2-D resistivity method in studying the slope failures

    Science.gov (United States)

    Maslinda, Umi; Nordiana, M. M.; Bery, A. A.

    2017-07-01

    Slope failures have become the main focus for infrastructures development on hilly areas in Malaysia especially the development of tourism and residential. Lack of understanding and information of the subsoil conditions and geotechnical issues are the main cause of the slope failures. The failures happened are due to a combination of few factors such as topography, climate, geology and land use. 2-D resistivity method was conducted at the collapsed area in Selangor. The 2-D resistivity was done to study the instability of the area. The collapsed occurred because of the subsurface materials was unstable. Pole-dipole array was used with 5 m minimum electrode spacing for the 2-D resistivity method. The data was processed using Res2Dinv software and the porosity was calculated using Archie's law equation. The results show that the saturated zone (1-100 Ωm), alluvium or highly weathered rock (100-1000 Ωm), boulders (1600-7000 Ωm) and granitic bedrock (>7000 Ωm). Generally, the slope failures or landslides occur during the wet season or after rainfall. It is because of the water infiltrate to the slope and cause the saturation of the slope which can lead to landslides. Then, the porosity of saturated zone is usually high because of the water content. The area of alluvium or highly weathered rock and saturated zone have high porosity (>20%) and the high porosity also dominated at almost all the collapsed area which means that the materials with porosity >20% is potential to be saturated, unstable and might trigger slope failures.

  4. Systematic characterization of porosity and mass transport and mechanical properties of porous polyurethane scaffolds.

    Science.gov (United States)

    Wang, Yu-Fu; Barrera, Carlos M; Dauer, Edward A; Gu, Weiyong; Andreopoulos, Fotios; Huang, C-Y Charles

    2017-01-01

    One of the key challenges in porous scaffold design is to create a porous structure with desired mechanical function and mass transport properties which support delivery of biofactors and development of function tissue substitute. In recent years, polyurethane (PU) has become one of the most popular biomaterials in various tissue engineering fields. However, there are no studies fully investigating the relations between porosity and both mass transport and mechanical properties of PU porous scaffolds. In this paper, we fabricated PU scaffolds by combining phase inversion and salt (sodium chloride) leaching methods. The tensile and compressive moduli were examined on PU scaffolds fabricated with different PU concentrations (25%, 20% and 15% w/v) and salt/PU weight ratios (9/1, 6/1, 3/1 and 0/1). The mass transport properties of PU scaffolds including hydraulic permeability and glucose diffusivity were also measured. Furthermore, the relationships between the porosity and mass transport and mechanical properties of porous PU scaffold were systemically investigated. The results demonstrated that porosity is a key parameter which governs both mass transport and mechanical properties of porous PU scaffolds. With similar pore sizes, the mass transport and mechanical properties of porous PU scaffold can be described as single functions of porosity regardless of initial PU concentration. The relationships between scaffold porosity and properties can be utilized to facilitate porous PU scaffold fabrication with specific mass transport and mechanical properties. The systematic approach established in this study can be applied to characterization of other biomaterials for scaffold design and fabrication. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Depolarized haze of nano-porous AAO film via porosity and aspect control

    Science.gov (United States)

    Tseng, Chun-Wei; Lin, Yung-Hsiang; Cheng, Chih-Hsien; Lin, Gong-Ru

    2018-01-01

    Multiple scattering induced haze and depolarization effects of nano-porous AAO films controlled by detuning the porosity and aspect ratio of the nano holes are investigated. The nano-porous AAO film with its porosity increasing from 12.6% to 19.3% enhances the scattering of the incident laser beam with its maximal scattering angle enlarged from 5° to 8° under TM-mode incidence and from 6° to 10° under TE-mode incidence. Because of multiple scattering within the porous holes of the AAO, the depolarization on the reflected beam by transferring its electric field from horizontal to the vertical such that the polarization ratio is degraded with a randomized haze. The porosity of AAO surface broadens from 12.6% to 19.3% when increasing the bias voltage from 40 to 60 V during the second-step of the electro-chemical anodization process, which essentially adjusts the polarization ratio under TM-mode and TE-mode incidences raise from 0.31 to 0.35 and from 0.32 to 0.48, respectively. The depolarized haze of the nano-porous AAO film is correlated with its porosity and aspect ratio controlled by the pore size and etched depth of the AAO. Under TM-mode incidence, the simulated polarization ratio increases from 0.35 to 0.38, which correlates well with experimental results. In contrast, the experiment result slightly deviates from the theoretical prediction as the TE-mode field interacts more surface area than the TM-mode field does. Such a nano-porous AAO exhibits tunable depolarized haze via the control porosity and aspect ratio, which is particularly suitable to serve as the catalytic buffer for synthesizing the hydrophobic and hazed solar energy converters.

  6. Tailoring Zeolite ZSM-5 Crystal Morphology/Porosity through Flexible Utilization of Silicalite-1 Seeds as Templates: Unusual Crystallization Pathways in a Heterogeneous System.

    Science.gov (United States)

    Zhang, Hongbin; Zhao, Yang; Zhang, Hongxia; Wang, Peicheng; Shi, Zhangping; Mao, Jianjiang; Zhang, Yahong; Tang, Yi

    2016-05-17

    Diffusion limitation in micropores of zeolites leads to a demand for optimization of zeolite morphology and/or porosity. However, tailoring crystallization processes to realize targeted morphology/porosity is a major challenge in zeolite synthesis. On the basis of previous work on the salt-aided, seed-induced route, the template effect of seeds on the formation of micropores, mesopores and even macropores was further explored to selectively achieve desired hierarchical architectures. By carefully investigating the crystallization processes of two typical samples with distinct crystal morphologies, namely, 1) nanocrystallite-oriented self-assembled ZSM-5 zeolite and 2) enriched intracrystal mesoporous ZSM-5 zeolite, a detailed mechanism is proposed to clarify the role of silicalite-1 seeds in the formation of diverse morphologies in a salt-rich heterogeneous system, combined with the transformation of seed-embedded aluminosilicate gel. On the basis of these conclusions, the morphologies/porosities of products were precisely tailored by deliberately adjusting the synthesis parameters (KF/Si, tetrapropylammonium bromide/Si and H2 O/Si ratios and type of organic template) to regulate the kinetics of seed dissolution and seed-induced recrystallization. This work may not only provide a practical route to control zeolite crystallization for tailoring crystal morphology, but also expands the knowledge of crystal growth mechanisms in a heterogeneous system. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. To what extent can cortical bone millimeter-scale elasticity be predicted by a two-phase composite model with variable porosity?

    Science.gov (United States)

    Granke, Mathilde; Grimal, Quentin; Parnell, William J; Raum, Kay; Gerisch, Alf; Peyrin, Françoise; Saïed, Amena; Laugier, Pascal

    2015-01-01

    An evidence gap exists in fully understanding and reliably modeling the variations in elastic anisotropy that are observed at the millimeter scale in human cortical bone. The porosity (pore volume fraction) is known to account for a large part, but not all, of the elasticity variations. This effect may be modeled by a two-phase micromechanical model consisting of a homogeneous matrix pervaded by cylindrical pores. Although this model has been widely used, it lacks experimental validation. The aim of the present work is to revisit experimental data (elastic coefficients, porosity) previously obtained from 21 cortical bone specimens from the femoral mid-diaphysis of 10 donors and test the validity of the model by proposing a detailed discussion of its hypotheses. This includes investigating to what extent the experimental uncertainties, pore network modeling, and matrix elastic properties influence the model's predictions. The results support the validity of the two-phase model of cortical bone which assumes that the essential source of variations of elastic properties at the millimeter-scale is the volume fraction of vascular porosity. We propose that the bulk of the remaining discrepancies between predicted stiffness coefficients and experimental data (RMSE between 6% and 9%) is in part due to experimental errors and part due to small variations of the extravascular matrix properties. More significantly, although most of the models that have been proposed for cortical bone were based on several homogenization steps and a large number of variable parameters, we show that a model with a single parameter, namely the volume fraction of vascular porosity, is a suitable representation for cortical bone. The results could provide a guide to build specimen-specific cortical bone models. This will be of interest to analyze the structure-function relationship in bone and to design bone-mimicking materials. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All

  8. New frontiers in open innovation

    CERN Document Server

    Vanhaverbeke, Wim; West, Joel

    2014-01-01

    Companies have to innovate to stay competitive, and they have to collaborate with other organizations to innovate effectively. Although the benefits of "open innovation" have been described in detail before, mechanisms underlying how companies can be successful "open innovators" have not be understood well. A growing community of innovation management researchers started to develop different frameworks to understand open innovation in a more systematic way. This book provides a thorough examination of research conducted to date on open innovation, as well as a comprehensive overview of what will be the most important, most promising and most relevant research topics in this area during the next decade. "Open Innovation: Researching a new paradigm" (OUP 2006) was the first initiative to bring open innovation closer to the academic community. Open innovation research has since then been growing in an exponential way and research has evolved in different and unexpected directions. As the research field is growin...

  9. Age, double porosity, and simple reaction modifications for the MOC3D ground-water transport model

    Science.gov (United States)

    Goode, Daniel J.

    1999-01-01

    This report documents modifications for the MOC3D ground-water transport model to simulate (a) ground-water age transport; (b) double-porosity exchange; and (c) simple but flexible retardation, decay, and zero-order growth reactions. These modifications are incorporated in MOC3D version 3.0. MOC3D simulates the transport of a single solute using the method-ofcharacteristics numerical procedure. The age of ground water, that is the time since recharge to the saturated zone, can be simulated using the transport model with an additional source term of unit strength, corresponding to the rate of aging. The output concentrations of the model are in this case the ages at all locations in the model. Double porosity generally refers to a separate immobilewater phase within the aquifer that does not contribute to ground-water flow but can affect solute transport through diffusive exchange. The solute mass exchange rate between the flowing water in the aquifer and the immobile-water phase is the product of the concentration difference between the two phases and a linear exchange coefficient. Conceptually, double porosity can approximate the effects of dead-end pores in a granular porous media, or matrix diffusion in a fractured-rock aquifer. Options are provided for decay and zero-order growth reactions within the immobilewater phase. The simple reaction terms here extend the original model, which included decay and retardation. With these extensions, (a) the retardation factor can vary spatially within each model layer, (b) the decay rate coefficient can vary spatially within each model layer and can be different for the dissolved and sorbed phases, and (c) a zero-order growth reaction is added that can vary spatially and can be different in the dissolved and sorbed phases. The decay and growth reaction terms also can change in time to account for changing geochemical conditions during transport. The report includes a description of the theoretical basis of the model, a

  10. Porosity and permeability evolution of vesicular basalt reservoirs with increasing depth: constraints from the Big Island of Hawai'i

    Science.gov (United States)

    Millett, John; Haskins, Eric; Thomas, Donald; Jerram, Dougal; Planke, Sverre; Healy, Dave; Kück, Jochem; Rossetti, Lucas; Farrell, Natalie; Pierdominici, Simona

    2017-04-01

    Volcanic reservoirs are becoming increasingly important in the targeting of petroleum, geothermal and water resources globally. However, key areas of uncertainty in relation to volcanic reservoir properties during burial in different settings remain. In this contribution, we present results from borehole logging and sampling operations within two fully cored c. 1.5 km deep boreholes, PTA2 and KMA1, from the Humúula saddle region on the Big Island of Hawai'i. The boreholes were drilled as part of the Humu'ula Groundwater Research Project (HGRP) between 2013-2016 and provide unique insights into the evolution of pore structure with increasing burial in a basaltic dominated lava sequence. The boreholes encounter mixed sequences of 'a'ā, pāhoehoe and transitional lava flows along with subsidiary intrusions and sediments from the shield to post-shield phases of Mauna Kea. Borehole wireline data including sonic, spectral gamma and Televiewer imagery were collected along with density, porosity, permeability and ultrasonic velocity laboratory measurements from core samples. A range of intra-facies were sampled for analysis from various depths within the two boreholes. By comparison with core data, the potential for high resolution Televiewer imaging to reveal spectacular intra-facies features including individual vesicles, vesicle segregations, 'a'ā rubble zones, intrusive contacts, and intricate pāhoehoe lava flow lobe morphologies is demonstrated. High quality core data enables the calibration of Televiewer facies enabling improved interpretation of volcanic reservoir features in the more common exploration scenario where core is absent. Laboratory results record the ability of natural vesicular basalt samples to host very high porosity (>50%) and permeability (>10 darcies) within lava flow top facies which we demonstrate are associated with vesicle coalescence and not micro-fractures. These properties may be maintained to depths of c. 1.5 km in regions of limited

  11. Ready to be Open?

    DEFF Research Database (Denmark)

    Monteiro, L. Felipe; Mol, Michael J.; Birkinshaw, Julian

    2016-01-01

    This paper provides new theory and evidence about the benefits of openness on a firm's innovation performance and, more importantly, the specific firm-level contingencies under which those benefits are more (or less) likely to be observed. Building on Dyer and Singh's (1998) relational view, we...... suggest that a firm's lack of resources and absorptive capacity, as well as its use of secrecy, are significant barriers to benefiting from openness to external knowledge. Using responses from 12,152 firms to the fourth and fifth UK versions of the Community Innovation Survey (CIS), we generate findings...

  12. Ready to be Open?

    DEFF Research Database (Denmark)

    Monteiro, L. Felipe; Mol, Michael J.; Birkinshaw, Julian

    This paper provides new theory and evidence about the benefits of openness on a firm's innovation performance and, more importantly, the specific firm-level contingencies under which those benefits are more (or less) likely to be observed. Building on Dyer and Singh's (1998) relational view, we...... suggest that a firm's lack of resources and absorptive capacity, as well as its use of secrecy, are significant barriers to benefiting from openness to external knowledge. Using responses from 12,152 firms to the fourth and fifth UK versions of the Community Innovation Survey (CIS) we generate findings...

  13. Using OpenRefine

    CERN Document Server

    Verborgh, Ruben

    2013-01-01

    The book is styled on a Cookbook, containing recipes - combined with free datasets - which will turn readers into proficient OpenRefine users in the fastest possible way.This book is targeted at anyone who works on or handles a large amount of data. No prior knowledge of OpenRefine is required, as we start from the very beginning and gradually reveal more advanced features. You don't even need your own dataset, as we provide example data to try out the book's recipes.

  14. Open source molecular modeling.

    Science.gov (United States)

    Pirhadi, Somayeh; Sunseri, Jocelyn; Koes, David Ryan

    2016-09-01

    The success of molecular modeling and computational chemistry efforts are, by definition, dependent on quality software applications. Open source software development provides many advantages to users of modeling applications, not the least of which is that the software is free and completely extendable. In this review we categorize, enumerate, and describe available open source software packages for molecular modeling and computational chemistry. An updated online version of this catalog can be found at https://opensourcemolecularmodeling.github.io. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  15. Fish skin provides invisibility in open ocean (image 11)

    National Science Foundation

    2017-02-10

    Full Text Available Skin preparation from fish shows birefringence under cross polarization microscopy Skin preparation from fish shows birefringence under cross polarization microscopySkin preparation from fish shows birefringence under cross polarization microscopy Skin pr

  16. Open access, open education resources and open data in Uganda ...

    African Journals Online (AJOL)

    ... students organized a 3 day workshop Open Access, Open Education Resources and Open Data in Kampala from 15-18 December 2014. One of the aims of the workshop was to engage the Open Access movement in Uganda which encompasses the scientific community, librarians, academia, researchers and students.

  17. Determination of the Porosity of PLGA Microparticles by Tracking Their Sedimentation Velocity Using a Flow Imaging Microscope (FlowCAM).

    Science.gov (United States)

    Sediq, A S; Waasdorp, S K D; Nejadnik, M R; van Beers, M M C; Meulenaar, J; Verrijk, R; Jiskoot, W

    2017-05-01

    To investigate whether particle sedimentation velocity tracking using a flow imaging microscope (FlowCAM) can be used to determine microparticle porosity. Two different methods were explored. In the first method the sedimentation rate of microparticles was tracked in suspending media with different densities. The porosity was calculated from the average apparent density of the particles derived by inter- or extrapolation to the density of a suspending medium in which the sedimentation velocity was zero. In the second method, the microparticle size and sedimentation velocity in one suspending fluid were used to calculate the density and porosity of individual particles by using the Stokes' law of sedimentation. Polystyrene beads of different sizes were used for the development, optimization and validation of the methods. For both methods we found porosity values that were in excellent agreement with the expected values. Both methods were applied to determine the porosity of three PLGA microparticle batches with different porosities (between about 4 and 52%). With both methods we obtained microparticle porosity values similar to those obtained by mercury intrusion porosimetry. We developed two methods to determine average microparticle density and porosity by sedimentation velocity tracking, using only a few milligrams of powder.

  18. Porosity and sonic velocity depth trends of Eocene chalk in Atlantic Ocean: Influence of effective stress and temperature

    DEFF Research Database (Denmark)

    Awedalkarim, Ahmed; Fabricius, Ida Lykke

    2014-01-01

    . This indicates pore-filling cementation via an activation energy mechanism. We proposed a predictive equation for porosity reduction with burial stress. This equation is relevant for basin analysis and hydrocarbon exploration to predict porosity if sonic velocity data for subsurface chalk is available....

  19. Quantitative integration of seismic and GPR reflections to derive unique estimates for water saturation and porosity in subsoil

    NARCIS (Netherlands)

    Ghose, R.; Slob, E.C.

    2006-01-01

    For shallow subsoil, the estimates of in-situ porosity and water saturation are important, but until now it has been difficult to estimate them reliably. We relate seismic and GPR reflection coefficients to porosity and water saturation using a shared earth model. Using this model, we propose a

  20. Effect of impregnation pressure and time on the porosity, structure and properties of polyacrylonitrile-fiber based carbon composites

    Science.gov (United States)

    Venugopalan, Ramani; Roy, Mainak; Thomas, Susy; Patra, A. K.; Sathiyamoorthy, D.; Tyagi, A. K.

    2013-02-01

    Carbon-carbon composites may find applications in critical parts of advanced nuclear reactors. A series of carbon-carbon composites were prepared using polyacrylonitrile (PAN) based carbon fibers. The materials were densified by impregnating two-dimensional (2D) preforms with liquid phenol formaldehyde resin at different pressures and for different periods of time and then carbonizing those by slowly heating at 1000 °C. Effects of the processing parameters on the structure of the composites were extensively studied. The study showed conclusively that open porosity decreased with increasing impregnation pressure, whereas impregnation time had lesser effect. Matrix-resin bonding also improved at higher pressure. d002 spacing decreased and ordering along c-axis increased with concomitant increase in sp2-carbon fraction at higher impregnation pressures. The fiber reinforced composites exhibited short range ordering of carbon atoms and satisfied structural conditions (d002 values) of amorphous carbon according to the turbostratic model for non-graphitic carbon materials. The composites had pellet-density of ˜85% of the theoretical value, low thermal expansion and negligible neutron-poisoning. They maintained structural integrity and retained disordered nature even on heat-treatment at ca. 1800 °C.

  1. KAUST Open Access policy

    KAUST Repository

    Baessa, Mohamed A.

    2017-03-07

    The transition to open access (OA) is being driven by funders, libraries, researchers and publishers around the world, and is having an impact on us all. It is inevitable that different countries, organisations and disciplines are moving at different rates towards an OA model, and it is this that we will focus on in this session. Drawing on experiences from across Europe and the Middle East we will provide perspectives from both a global publisher and institutions based in the region. Taylor & Francis take a flexible, evidence-based approach to open access, providing a choice of publication routes for our authors, and a choice of agreements for our library customers. Carolyn will outline some of the open access developments, opportunities and challenges at Taylor & Francis. The library plays a critical role in facilitating open access for their researchers, from managing a repository to providing support and information on the OA publication process to their authors. Janis Tyhurst and Dr Imad Bachir will each give an overview of how this is being managed by their institution. There will be an opportunity for questions and discussion with the panel.

  2. Air pollution abatement performances of green infrastructure in open road and built-up street canyon environments - A review

    Science.gov (United States)

    Abhijith, K. V.; Kumar, Prashant; Gallagher, John; McNabola, Aonghus; Baldauf, Richard; Pilla, Francesco; Broderick, Brian; Di Sabatino, Silvana; Pulvirenti, Beatrice

    2017-08-01

    Intensifying the proportion of urban green infrastructure has been considered as one of the remedies for air pollution levels in cities, yet the impact of numerous vegetation types deployed in different built environments has to be fully synthesised and quantified. This review examined published literature on neighbourhood air quality modifications by green interventions. Studies were evaluated that discussed personal exposure to local sources of air pollution under the presence of vegetation in open road and built-up street canyon environments. Further, we critically evaluated the available literature to provide a better understanding of the interactions between vegetation and surrounding built-up environments and ascertain means of reducing local air pollution exposure using green infrastructure. The net effects of vegetation in each built-up environment are also summarised and possible recommendations for the future design of green infrastructure are proposed. In a street canyon environment, high-level vegetation canopies (trees) led to a deterioration in air quality, while low-level green infrastructure (hedges) improved air quality conditions. For open road conditions, wide, low porosity and tall vegetation leads to downwind pollutant reductions while gaps and high porosity vegetation could lead to no improvement or even deteriorated air quality. The review considers that generic recommendations can be provided for vegetation barriers in open road conditions. Green walls and roofs on building envelopes can also be used as effective air pollution abatement measures. The critical evaluation of the fundamental concepts and the amalgamation of key technical features of past studies by this review could assist urban planners to design and implement green infrastructures in the built environment.

  3. Quantifying multiscale porosity and fracture aperture distribution in granite cores using computed tomography

    Science.gov (United States)

    Wenning, Quinn; Madonna, Claudio; Joss, Lisa; Pini, Ronny

    2017-04-01

    Knowledge of porosity and fracture (aperture) distribution is key towards a sound description of fluid transport in low-permeability rocks. In the context of geothermal energy development, the ability to quantify the transport properties of fractures is needed to in turn quantify the rate of heat transfer, and, accordingly, to optimize the engineering design of the operation. In this context, core-flooding experiments coupled with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) represent a powerful tool for making direct observations of these properties under representative geologic conditions. This study focuses on quantifying porosity and fracture aperture distribution in a fractured westerly granite core by using two recently developed experimental protocols. The latter include the use of a highly attenuating gas [Vega et al., 2014] and the application of the so-called missing CT attenuation method [Huo et al., 2016] to produce multidimensional maps of the pore space and of the fractures. Prior to the imaging experiments, the westerly granite core (diameter: 5 cm, length: 10 cm) was thermally shocked to induce micro-fractured pore space; this was followed by the application of the so-called Brazilian method to induce a macroscopic fracture along the length of the core. The sample was then mounted in a high-pressure aluminum core-holder, exposed to a confining pressure and placed inside a medical CT scanner for imaging. An initial compressive pressure cycle was performed to remove weak asperities and reduce the hysteretic behavior of the fracture with respect to effective pressure. The CT scans were acquired at room temperature and 0.5, 5, 7, and 10 MPa effective pressure under loading and unloading conditions. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated at the desired pressure with a high precision pump. Highly transmissible krypton and helium gases were used as

  4. OpenLabNotes

    DEFF Research Database (Denmark)

    List, Markus; Franz, Michael; Tan, Qihua

    2015-01-01

    the longevity of the providers. Turning towards free alternatives, however, raises questions about data protection, which are not sufficiently addressed by available solutions. To serve as legal documents, ELNs must prevent scientific fraud through technical means such as digital signatures. It would also......LabFramework, a powerful and flexible laboratory information management system. In contrast to comparable solutions, it allows to protect the intellectual property of its users by offering data protection with digital signatures. OpenLabNotes effectively Closes the gap between research documentation and sample management...... be advantageous if an ELN was Integrated with a laboratory information management system to allow for a comprehensive documentation of experimental work including the location of samples that were used in a particular experiment. Here, we present OpenLabNotes, which adds state-of-the-art ELN capabilities to Open...

  5. The Case for Open Metadata

    OpenAIRE

    Chessell, Mandy

    2017-01-01

    An open source project called Apache Atlas was approved as an incubator project on 5th May 2015. This project aims to provide an open metadata repository and information governance frameworks. The appearance of metadata management in open source offers an exciting opportunity to rethink the way we manage data in data science projects to create trust to both share and consume data. This paper describes the role of Apache Atlas in changing the availability and quality of metadata, which will in...

  6. High Resolution Audiomagnetotelluric Investigation of the Porosity at the Margin of the Hudson Bay Basin, Canada

    Science.gov (United States)

    Craven, J. A.; Roberts, B.

    2012-12-01

    Seismic exploration from 1968 to 1985 within the intracratonic Hudson Bay basin in northern Canada resulted in five dry wells drilled on a structural high in the central part of the basin (Hamblin, 2008). Recent work (Bertrand and Malo, 2012) has indicated successions at margins of the basin are well within the oil and gas "window". To test this conjecture a magnetotelluric (MT) survey was carried out in the vicinity of Churchill, Manitoba, at the margin of the basin. The primary goal of the survey was to identify potential source or reservoir rocks in the Upper Ordovician section of the Palaeozoic strata. MT surveys have been utilized in the northeastern portion of the Williston basin and have successfully imaged lower Palaeozoic carbonate units (Gowan et al., 2009). The MT method provides information on the electrical conductivity of the subsurface though the measurement of the natural time-varying electric and magnetic fields at the surface. Due to the dependence of the depth of investigation of the fields on their frequency, an estimate of conductivity variation with depth can be attained. A total of 46 high frequency audio-magnetotelluric (AMT) sites were collected, 38 along one approximately N-S corridor perpendicular to the coastline and 8 in a more E-W direction closer to the town of Churchill. Simultaneous collection of broadband MT data (BBMT) at a limited number of sites was done in order to calculate a response function over a wider range of frequencies at each AMT site. The combined AMT and BBMT MT data have been edited and processed to produce response functions at all sites, and 1-D modelling has provided resistivity vs. depth curves in the top 200 m of the basin. The 1-D models have been stitched together to create a continuous, approximately N-S resistivity section. In addition, the data have been input to a 3D inversion program and preliminary 3D resistivity and conductivity volumes have been generated along with an estimate of 3-D porosity

  7. Composition, mineralogy, and porosity of multiple asteroid systems from visible and near-infrared spectral data

    Science.gov (United States)

    Lindsay, S. S.; Marchis, F.; Emery, J. P.; Enriquez, J. E.; Assafin, M.

    2015-02-01

    We aim to provide a taxonomic and compositional characterization of Multiple Asteroid Systems (MASs) located in the main belt (MB) using visible (0.45-0.85 μm) and near-infrared (0.7-2.5 μm) spectral data of 42 MB MASs. The compositional and mineralogical analysis is applied to determine meteorite analogs for the MASs, which, in turn, are applied to the MAS density measurements of Marchis et al. (Marchis et al. [2012]. Icarus 221, 1130-1161) to estimate the porosity of the systems. The macroporosities are used to evaluate the primary MAS formation hypotheses. Our spectral survey consists of visible and near-infrared spectral data. The visible observing campaign includes 25 MASs obtained using the Southern Astrophysical Research (SOAR) telescope with the Goodman High Throughput Spectrometer. The infrared observing campaign includes 34 MASs obtained using the NASA Infrared Telescope Facility (IRTF) with the SpeX spectragraph. For completeness, both visible and NIR data sets are supplemented with publicly available data, and the data sets are combined where possible. The MASs are classified using the Bus-DeMeo taxonomic system. In order to determine mineralogy and meteorite analog, we perform a NIR spectral band parameter analysis using a new analysis routine, the Spectral Analysis Routine for Asteroids (SARA). The SARA routine determines band centers, areas, and depths by utilizing the diagnostic absorption features near 1- and 2-μm due to Fe2+ crystal field transitions in olivine + pyroxene and pyroxene, respectively. The band parameter analysis provides the Gaffey subtype for the S-complex MASs; the relative abundance olivine-to-pyroxene ratio; and olivine and pyroxene modal abundances for S-complex and V-type MASs. This mineralogical information is then applied to determine meteorite analogs. Through applying calibration studies, we are able to determine the H, L, and LL meteorite analogs for 15 MASs with ordinary chondrite-like (OC) mineralogies. We observe an

  8. On the use of crystalline admixtures in cement based construction materials: from porosity reducers to promoters of self healing

    Science.gov (United States)

    Ferrara, Liberato; Krelani, Visar; Moretti, Fabio

    2016-08-01

    The project detailed in this paper aims at a thorough characterization of the effects of crystalline admixtures, currently employed as porosity reducing admixtures, on the self-healing capacity of the cementitious composites, i.e. their capacity to completely or partially re-seal cracks and, in case, also exhibit recovery of mechanical properties. The problem has been investigated with reference to both a normal strength concrete (NSC) and a high performance fibre reinforced cementitious composite (HPFRCC). In the latter case, the influence of flow-induced fibre alignment has also been considered in the experimental investigation. With reference to either 3-point (for NSC) or 4-point (for HPFRCC) bending tests performed up to controlled crack opening and up to failure, respectively before and after exposure/conditioning recovery of stiffness and stress bearing capacity has been evaluated to assess the self-healing capacity. In a durability-based design framework, self-healing indices to quantify the recovery of mechanical properties will also be defined. In NSC, crystalline admixtures are able to promote up to 60% of crack sealing even under exposure to open air. In the case of HPFRCCs, which would already feature autogenous healing capacity because of their peculiar mix compositions, the synergy between the dispersed fibre reinforcement and the action of the crystalline admixture has resulted in a likely ‘chemical pre-stressing’ of the same reinforcement, from which the recovery of mechanical performance of the material has greatly benefited, up to levels even higher than the performance of the virgin un-cracked material.

  9. BIB-SEM of representative area clay structures paving towards an alternative model of porosity

    Science.gov (United States)

    Desbois, G.; Urai, J. L.; Houben, M.; Hemes, S.; Klaver, J.

    2012-04-01

    A major contribution to understanding the sealing capacity, coupled flow, capillary processes and associated deformation in clay-rich geomaterials is based on detailed investigation of the rock microstructures. However, the direct characterization of pores in representative elementary area (REA) and below µm-scale resolution remains challenging. To investigate directly the mm- to nm-scale porosity, SEM is certainly the most direct approach, but it is limited by the poor quality of the investigated surfaces. The recent development of ion milling tools (BIB and FIB; Desbois et al, 2009, 2011; Heath et al., 2011; Keller et al., 2011) and cryo-SEM allows respectively producing exceptional high quality polished cross-sections suitable for high resolution porosity SEM-imaging at nm-scale and investigating samples under wet conditions by cryogenic stabilization. This contribution focuses mainly on the SEM description of pore microstructures in 2D BIB-polished cross-sections of Boom (Mol site, Belgium) and Opalinus (Mont Terri, Switzerland) clays down to the SEM resolution. Pores detected in images are statistically analyzed to perform porosity quantification in REA. On the one hand, BIB-SEM results allow retrieving MIP measurements obtained from larger sample volumes. On the other hand, the BIB-SEM approach allows characterizing porosity-homogeneous and -predictable islands, which form the elementary components of an alternative concept of porosity/permeability model based on pore microstructures. Desbois G., Urai J.L. and Kukla P.A. (2009) Morphology of the pore space in claystones - evidence from BIB/FIB ion beam sectioning and cryo-SEM observations. E-Earth, 4, 15-22. Desbois G., Urai J.L., Kukla P.A., Konstanty J. and Baerle C. (2011). High-resolution 3D fabric and porosity model in a tight gas sandstone reservoir: a new approach to investigate microstructures from mm- to nm-scale combining argon beam cross-sectioning and SEM imaging . Journal of Petroleum Science

  10. Opening Address

    Science.gov (United States)

    Crovini, L.

    1994-01-01

    Ladies and Gentlemen To quote Mr Jean Terrien: "Physics must be one step ahead of metrology". A long-serving Director of the BIPM, he said these words when visiting the IMGC in 1970 as a member of the scientific board of our Institute. At that time it was still an open question whether the IMGC should start research work on the absolute measurement of silicon lattice spacing. Mr Terrien underlined the revolutionary character of x-ray interferometry and, eventually, he caused the balance needle to lean towards the ... right direction. Mr Terrien correctly foresaw that, like Michelson's interferometer of 1880, x-ray interferometry could have a prominent place in today's science and technology. And while, in the first case, after more than a century we can see instruments based on electromagnetic wave interaction within every one's reach in laboratories and, sometimes, in workshops, in the second case, twenty-five years since the first development of an x-ray interferometer we can witness its role in nanometrology. Today and tomorrow we meet to discuss how to go beyond the sixth decimal place in the value of the Avogadro constant. We are aware that the quest for this achievement requires the cooperation of scientists with complementary capabilities. I am sure that the present workshop is a very good opportunity to present and discuss results and to improve and extend existing cooperation. The new adjustment of fundamental constants envisaged by the CODATA Task Group is redoubling scientists' efforts to produce competitive values of NA. The results of the measurements of the silicon lattice spacing in terms of an optical wavelength, which were available for the 1986 adjustment, combined with the determination of silicon molar volume, demonstrate how such an NA determination produces a consistent set of other constants and opens the way to a possible redefinition of the kilogram. We shall see in these two days how far we have progressed along this road. For us at the

  11. The open innovation research landscape

    DEFF Research Database (Denmark)

    Bogers, Marcel; Zobel, Ann-Kristin; Afuah, Allan

    2017-01-01

    This paper provides an overview of the main perspectives and themes emerging in research on open innovation (OI). The paper is the result of a collaborative process among several OI scholars – having a common basis in the recurrent Professional Development Workshop on ‘Researching Open Innovation...

  12. Opening the door to innovation.

    Science.gov (United States)

    Schuurman, Janine; Graus, Yvo F; Labrijn, Aran F; Ruuls, Sigrid; Parren, Paul W H I

    2014-01-01

    Open innovation is the new buzz, with initiatives popping up left and right. Here, we give a personal perspective on a very successful, knowledge-driven innovation initiated in an academia- industry alliance, which culminated in technology platforms that enable the generation of therapeutic antibodies with novel properties. To start, we provide a general background on open innovation in the drug development field.

  13. Porosity of spacer-filled channels in spiral-wound membrane systems: Quantification methods and impact on hydraulic characterization

    KAUST Repository

    Siddiqui, Amber

    2017-04-13

    The porosity of spacer-filled feed channels influences the hydrodynamics of spiral-wound membrane systems and impacts the overall performance of the system. Therefore, an exact measurement and a detailed understanding of the impact of the feed channel porosity is required to understand and improve the hydrodynamics of spiral-wound membrane systems applied for desalination and wastewater reuse. The objectives of this study were to assess the accuracy of porosity measurement techniques for feed spacers differing in geometry and thickness and the consequences of using an inaccurate method on hydrodynamic predictions, which may affect permeate production. Six techniques were applied to measure the porosity namely, three volumetric calculations based on spacer strand count together with cuboidal (SC), cylindrical (VCC) and ellipsoidal volume calculation (VCE) and three independent techniques based on volume displacement (VD), weight and density (WD) and computed tomography scanning (CT). The CT method was introduced as an alternative for the other five already existing and applied methods in practice.Six feed spacers used for the porosity measurement differed in filament thickness, angle between the filaments and mesh-size. The results of the studies showed differences between the porosities, measured by the six methods. The results of the microscopic techniques SC, VCC and VCE deviated significantly from measurements by VD, WD and CT, which showed similar porosity values for all spacer types.Depending on the maximum deviation of the porosity measurement techniques from –6% to +6%, (i) the linear velocity deviations were −5.6% and +6.4% respectively and (ii) the pressure drop deviations were –31% and +43% respectively, illustrating the importance of an accurate porosity measurement. Because of the accuracy and standard deviation, the VD and WD method should be applied for the porosity determination of spacer-filled channels, while the CT method is recommended for

  14. Opening Windows

    Science.gov (United States)

    Bennett, Gayle

    2011-01-01

    Beth Kanter is working hard to get the word out about how best to get the word out. Kanter is CEO of Zoetica, which provides word-of-mouth communication services to nonprofits and socially conscious companies; a decade-long blogger on the topic of social media and nonprofits; and a popular conference speaker and trainer. She is also co-author of…

  15. In-situ observation of porosity formation during directional solidification of Al-Si casting alloys

    Directory of Open Access Journals (Sweden)

    Zhao Lei

    2011-02-01

    Full Text Available In-situ observation of porosity formation during directional solidification of two Al-Si alloys (7%Si and 13%Si was made by using of micro-focus X-ray imaging. In both alloys, small spherical pores initially form in the melt far away from the eutectic solid-liquid (S/L interface and then grow and coagulate during solidification. Some pores can float and escape from the solidifying melt front at a relatively high velocity. At the end of solidification, the remaining pores maintain spherical morphology in the near eutectic alloy but become irregular in the hypoeutectic alloy. This is attributed to different solidification modes and aluminum dendrite interactions between the two alloys. The mechanism of the porosity formation is briefly discussed in this paper.

  16. A small angle x-ray scattering study on the porosity of anthracite

    Energy Technology Data Exchange (ETDEWEB)

    Cohaut, N.; Blanche, C.; Duman, D.; Guet, J.M.; Rouzaud, J.N, [University of Orleans, Orleans (France)

    2000-07-01

    The SAXS technique was applied to anthracites to study their heterogeneous microtexture and the mechanism of partial graphitization during thermal treatment up to 2800{degree}C. The effects of heat treatment on the porosity were observed at 1600{degree}C and 2800{degree}C and compared with homogeneous microtextures of mesoporous saccharose-based coke and lamellar anthracene-based coke. The main feature observed on raw anthracites, displaying the least degree of natural maturation and the largest isotropic distribution of aromatic units, is the occurrence of a characteristic distance of 20 Angstrom. The porosity varies respectively from 19%, corresponding to a mean length chord of 97 Angstrom for least graphitized anthracites, to 10% and a mean length chord of 235 Angstrom for the most graphitized one.

  17. Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

    DEFF Research Database (Denmark)

    Sørensen, Morten Kanne; Fabricius, Ida Lykke

    2013-01-01

    Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......, however, show high attenuation and velocity dispersion remaining at high confining stress. Such dispersion is proposed to be caused by pressure gradients induced by compliant porosity within clay inclusions. By modeling the response of two extreme systems we quantify the possible effects of such clay......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...

  18. A new multi-zone model for porosity distribution in Al–Si alloy castings

    DEFF Research Database (Denmark)

    Tiedje, Niels Skat; Taylor, John A.; Easton, Mark A.

    2013-01-01

    A new multi-zone model is proposed that explains how porosity forms in various regions of a casting under different conditions and leads to distinct zonal differences in pore shape, size and distribution. This model was developed by considering the effect of cooling rate on solidification......) a central zone where the thermal gradient is low and equiaxed dendritic grains and eutectic cells grow at the centre of the casting and larger, rounded pores tend to form. The paper discusses how Si content, modification type and cooling conditions influence the location and size (i.e. depth) of each...... and distribution of porosity in Al–Si alloys cast as plates in moulds made with silica, ilmenite or zirconia sand cores or steel chills facing the major plate faces. The alloys cast were Al–7wt.% Si and Al–12.5wt.% Si in unmodified and modified forms, the latter with either Na or Sr addition. It is found that...

  19. A Porosity Method to Describe Complex 3D-Structures Theory and Application to an Explosion

    Directory of Open Access Journals (Sweden)

    M.-F. Robbe

    2006-01-01

    Full Text Available A theoretical method was developed to be able to describe the influence of structures of complex shape on a transient fluid flow without meshing the structures. Structures are considered as solid pores inside the fluid and act as an obstacle for the flow. The method was specifically adapted to fast transient cases.The porosity method was applied to the simulation of a Hypothetical Core Disruptive Accident in a small-scale replica of a Liquid Metal Fast Breeder Reactor. A 2D-axisymmetrical simulation of the MARS test was performed with the EUROPLEXUS code. Whereas the central internal structures of the mock-up could be described with a classical shell model, the influence of the 3D peripheral structures was taken into account with the porosity method. 

  20. Effects of porosity and crystallinity of glass ceramics on the in vivo bioactive response

    Energy Technology Data Exchange (ETDEWEB)

    Xin Renlong [School of Materials Science and Engineering, Chongqing University, Chongqing (China); Zhang Qiyi; Leng Yang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong (China); Chen Jiyong [Engineering Research Center in Biomaterials, Sichuan University, Chengdu (China)], E-mail: rlxin@cqu.edu.cn

    2008-12-15

    Two types of glass ceramics with different porosities and crystallinities were produced by sintering 45S5 Bioglass (registered) particulates. The in vivo bioactive response of the glass ceramics was evaluated by implanting them in rabbit muscle sites. After six weeks implantation, silicon-rich networks were observed on both types of ceramics, but the number of networks was much larger in the poorly crystallized dense ceramics than in the well crystallized porous ones. This indicated that the crystallization of glass ceramics retarded the formation of networks on surfaces. Apatite precipitation was found in pore areas of the porous ceramics, but not on the dense ones, suggesting that porosity was necessary for glass ceramics to induce apatite precipitation in a rabbit model. (communication)

  1. High Structural Stability of Textile Implants Prevents Pore Collapse and Preserves Effective Porosity at Strain

    Directory of Open Access Journals (Sweden)

    Uwe Klinge

    2015-01-01

    Full Text Available Reinforcement of tissues by use of textiles is encouraged by the reduced rate of recurrent tissue dehiscence but for the price of an inflammatory and fibrotic tissue reaction to the implant. The latter mainly is affected by the size of the pores, whereas only sufficiently large pores are effective in preventing a complete scar entrapment. Comparing two different sling implants (TVT and SIS, which are used for the treatment of urinary incontinence, we can demonstrate that the measurement of the effective porosity reveals considerable differences in the textile construction. Furthermore the changes of porosity after application of a tensile load can indicate a structural instability, favouring pore collapse at stress and questioning the use for purposes that are not “tension-free.”

  2. Effect of Temperature and Age of Concrete on Strength – Porosity Relation

    Directory of Open Access Journals (Sweden)

    T. Zadražil

    2004-01-01

    Full Text Available The compressive strengths of unsealed samples of concrete at the age of 180 days and have been measured at temperatures 20 °C, 300 °C, 600 °C and 900 °C. All of tests were performed for cold material. We compared our results with those obtained in [10] for the same type of concrete (age 28, resp. 90 days and measured at temperature ranging from 20 °C to 280 °C. Dependencies of compressive strength and porosity were correlated together and compared for the samples of age 28, 90 and 180 days. Behaviour of concrete of the age 90, resp. 180 days confirms generally accepted hypothesis that with increasing porosity strength of the concrete decreases. It has to be stressed out, howerer, that concrete samples of the age 28 days exhibit totally opposite dependency. 

  3. Robust automatic high resolution segmentation of SOFC anode porosity in 3D

    DEFF Research Database (Denmark)

    Jørgensen, Peter Stanley; Bowen, Jacob R.

    2008-01-01

    anode in 3D. The technique is based on numerical approximations to partial differential equations to evolve a 3D surface to the desired phase boundary. Vector fields derived from the experimentally acquired data are used as the driving force. The automatic segmentation compared to manual delineation......Routine use of 3D characterization of SOFCs by focused ion beam (FIB) serial sectioning is generally restricted by the time consuming task of manually delineating structures within each image slice. We apply advanced image analysis algorithms to automatically segment the porosity phase of an SOFC...... reveals and good correspondence and the two approaches are quantitatively compared. It is concluded that the. automatic approach is more robust, more reproduceable and orders of magnitude quicker than manual segmentation of SOFC anode porosity for subsequent quantitative 3D analysis. Lastly...

  4. Tailoring broadband acoustic energy suppression characteristics of double porosity metamaterials with compression constraints and mass inclusions.

    Science.gov (United States)

    Cui, Shichao; Harne, Ryan L

    2017-06-01

    A metamaterial that capitalizes on a double porosity architecture is introduced for controlling broadband acoustic energy suppression properties. When the metamaterial is subjected to static compressive stress, a global rotation of the internal metamaterial architecture is induced that softens the effective stiffness and results in a considerable means to tailor wave transmission and absorption properties. The influences of mass inclusions and compression constraints are examined by computational and experimental efforts. The results indicate that the mass inclusions and applied constraints can significantly impact the absorption and transmission properties of double porosity metamaterials, while the appropriate utilization of the underlying poroelastic media can further magnify these parametric influences. Based on the widespread implementation of compressed poroelastic media in applications, the results of this research uncover how internal metamaterial architecture and constraints may be exploited to enhance engineering noise control properties while using less poroelastic material mass.

  5. Intrinsic activation: the relationship between biomass inorganic content and porosity formation during pyrolysis.

    Science.gov (United States)

    Stratford, James P; Hutchings, Tony R; de Leij, Frans A A M

    2014-05-01

    The utility of pyrolytic carbons is closely related to their porosity and surface area, there is a clear benefit to the development of biomass pyrolysis processes which produce highly porous carbons. The results presented in this work demonstrate that by using biomass precursors with high inorganic content along with specified process conditions, carbons can be consistently produced with specific surface areas between 900 and 1600 m(2)/g. Results from 12 different source materials show that the formation of increased porosity in pyrolytic carbons is strongly associated with the presence of inorganic elements in the precursors including: magnesium, potassium and sulfur. It was found that pyrolysis of macro-algae can produce especially high specific surface area carbons (mean: 1500 m(2)/g), without externally applied activating agents. Using cheap readily available agricultural residues such as oilseed rape straw, pyrolytic carbons can be produced with specific surface areas of around 950 m(2)/g. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Effect of hierarchical porosity and phosphorus modification on the catalytic properties of zeolite Y

    Science.gov (United States)

    Li, Wenlin; Zheng, Jinyu; Luo, Yibin; Da, Zhijian

    2016-09-01

    The zeolite Y is considered as a leading catalyst for FCC industry. The acidity and porosity modification play important roles in determining the final catalytic properties of zeolite Y. The alkaline treatment of zeolite Y by dealumination and alkaline treatment with NaOH and NaOH&TBPH was investigated. The zeolites were characterized by X-ray diffraction, low-temperature adsorption of nitrogen, transmission electron microscope, NMR, NH3-TPD and IR study of acidity. Accordingly, the hierarchical porosity and acidity property were discussed systematically. Finally, the catalytic performance of the zeolites Y was evaluated in the cracking of 1,3,5-TIPB. It was found that desilication with NaOH&TBPH ensured the more uniform intracrystalline mesoporosity with higher microporosity, while preserving higher B/L ratio and moderate Brønsted acidities resulting in catalysts with the most appropriated acidity and then with better catalytic performance.

  7. Effect of temperature on porosity of iron ore sinter with biochar derived from EFB

    Science.gov (United States)

    Purwanto, H.; Rozhan, A. N.; Zakiyuddin, A.; Mohamad, A. S.

    2018-01-01

    In this research, the replacement of fossil fuel energy (coke) with oil palm empty fruit bunch as a potential energy in sintering of iron ore was investigated. Carbon derived biomass has been produced by using oil palm empty fruit bunch by heat treatment process. In the present investigation, sintering process was carried out by heating the mixed iron ore and biochar at various temperatures. The apparent density and porosity for iron sinter show a significant increase and gradual decrement as the temperature increase, respectively. The porosity of iron sinter shows a gradual decrement from 950 °C to 1050 °C but up to 1150 °C it shows a significant decrement about 44%. Inferring to the micrograph, the agglomeration and assimilation of sinter at high temperature is better compared with low sintering temperature.

  8. Effect of desulphurised waste on long-term porosity and pore structure of blended cement pastes

    Directory of Open Access Journals (Sweden)

    Jamal M. Khatib

    2016-09-01

    Full Text Available This paper presents some results on the porosity and pore size distribution of cement paste containing simulated desulphurised waste (SDW cured for 90 d. The SDW was chosen for the investigation due to the variability in chemical composition of real desulphurised waste as explained in previous papers. The SDW is a combination of 85% fly ash and 15% gypsum. The cement in the pastes was replaced with 0, 20 and 40% SDW. The water to binder ratio was 0.5. The binder consists of cement and SDW (by weight. After 90 d of curing, the porosity and pore size distribution tests were conducted on the pastes. Increasing the amount of SDW leads to an increase in the pore volume of the paste. There is no clear trend on the effect of SDW on the size of the pores.

  9. Providing Southern Perspectives on CSR

    DEFF Research Database (Denmark)

    Jeppesen, Søren; Kothuis, Bas

    The article seeks to contribute to the SMEs and CSR literature in developing countries by providing; a) a ‘Southern’ SME perspective, which includes the voices of managers and workers, b) a perspective of CSR, which opens up to informal CSR practices that SMEs undertake, and c) an analysis...

  10. Towards a Fundamental Understanding of the Evolution of Porosity and Permeability During Mineral Nucleation and Growth

    Science.gov (United States)

    Stack, A. G.; Wang, H. W.; Page, K.

    2016-12-01

    A fundamental understanding of how porosity and permeability evolve in response to geochemical reactions is necessary to accurately predict how the subsurface responds to anthropogenic perturbation. Historically, porosity and permeability occlusion due to mineral precipitation in particular have been treated using empirical expressions based on grain parameters such as Kozeny-Carmen, or a "bundle of tubes" approach that assumes that minerals nucleate and grow homogeneously over all rock surfaces. Recent results have called into question these assumptions by showing that there can be a distinct pore-size preference for precipitation reactions, but there is little agreement over whether a preference for precipitation in small or large pores. Pores with diameters in the nanometers (nanopores) in particular have the potential to display special reactivity and can constitute the majority of pores in fine-grained rocks such as shale. In this talk, I will show our recent results that illustrate the special reactivity of nanopores and discuss the path forward for using what we have learned to start to think about porosity and permeability relationships. In particular, I will show results on using synchrotron-based X-ray scattering (PDF analysis) to examine precipitation of calcium carbonate in nanoporous amorphous silica, as well as X-ray tomography results of barium sulfate precipitation in a glass bead column that show how the pore size in which precipitation occurs depends in part on the interaction between precipitate and substrate. To ground this experimental work in a relevant real-world system, I will lastly show recent results of how the porosity distribution of a nanoporous wellbore cement exposed to CO2 over the course of 30 years evolves during mineralization reactions.

  11. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part One?Porosity, Setting Times and Compressive Strength

    OpenAIRE

    Juliette Fitremann; Ariane Bercier; Olivier Lignon; Stéphane Gonçalves

    2010-01-01

    Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis) and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive str...

  12. Thermal porosity analysis of croscarmellose sodium and sodium starch glycolate by differential scanning calorimetry.

    Science.gov (United States)

    Faroongsarng, Damrongsak; Peck, Garnet E

    2003-12-30

    The aim of the study was to demonstrate the applicability of differential scanning calorimetry (DSC) on porosity analysis for cellulose and starch. Croscarmellose sodium (CCS) and sodium starch glycolate (SSG) were allowed to sorb moisture in 85%, 90%, 95%, and 100% relative humidity (RH) at 40 degrees C for 24 hours. The pretreated samples were then subjected to DSC running temperature ranging from 25 degrees C to -50 degrees C at a cooling rate of 10 degrees C/min. The cooling traces of water crystallization, if present, were transformed to porosity distribution via capillary condensation using Kelvin's equation. The porosity analysis of CCS and SSG was also done using nitrogen adsorption as a reference method. It was found that sorbed water could not be frozen (in cases of 85% and 90% RH) until the moisture content exceeded a cutoff value (in cases of 95% and 100% RH). The nonfreezable moisture content was referred to tightly bound, plasticizing water, whereas the frozen one may be attributed to loosely bound water condensation in pore structure of CCS and SSG surfaces. Not only capillary condensation but also the tightly bound, nonfreezable monolayer water lying along the inner pores of the surface contributed to porosity determination. Good agreement with less than 5% deviation of mean pore size was observed when the results were compared with nitrogen adsorption. The narrower pore size distributions, however, were obtained because of the limitations of the technique. It was concluded that pore analysis by DSC could be successful. Further research needs to be done to account for limitations and to extend the applicability of the technique.

  13. A Reconciliation of Packed Column Permeability Data: Column Permeability as a Function of Particle Porosity

    Directory of Open Access Journals (Sweden)

    Hubert M. Quinn

    2014-01-01

    Full Text Available In his textbook teaching of packed bed permeability, Georges Guiochon uses mobile phase velocity as the fluid velocity term in his elaboration of the Darcy permeability equation. Although this velocity frame makes a lot of sense from a thermodynamic point of view, it is valid only with respect to permeability at a single theoretical boundary condition. In his more recent writings, however, Guiochon has departed from his long-standing mode of discussing permeability in terms of the Darcy equation and has embraced the well-known Kozeny-Blake equation. In this paper, his teaching pertaining to the constant in the Kozeny-Blake equation is examined and, as a result, a new correlation coefficient is identified and defined herein based on the velocity frame used in his teaching. This coefficient correlates pressure drop and fluid velocity as a function of particle porosity. We show that in their experimental protocols, Guiochon et al. have not adhered to a strict material balance of permeability which creates a mismatch of particle porosity and leads to erroneous conclusions regarding the value of the permeability coefficient in the Kozeny-Blake equation. By correcting the experimental data to properly reflect particle porosity we reconcile the experimental results of Guiochon and Giddings, resulting in a permeability reference chart which is presented here for the first time. This reference chart demonstrates that Guiochon’s experimental data, when properly normalized for particle porosity and other related discrepancies, corroborates the value of 267 for the constant in the Kozeny-Blake equation which was derived by Giddings in 1965.

  14. Root porosity and radial oxygen loss related to arsenic tolerance and uptake in wetland plants

    Energy Technology Data Exchange (ETDEWEB)

    Li, H. [State Key Laboratory for Bio-control, and School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 (China); Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Ye, Z.H., E-mail: lssyzhh@mail.sysu.edu.c [State Key Laboratory for Bio-control, and School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 (China); Wei, Z.J. [School of Information and Technology, Guangdong University of Foreign Studies, Guangzhou 510275 (China); Wong, M.H., E-mail: mhwong@hkbu.edu.h [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

    2011-01-15

    The rates of radial oxygen loss (ROL), root porosity, concentrations of arsenic (As), iron (Fe) and manganese (Mn) in shoot and root tissues and on root surfaces, As tolerances, and their relationships in different wetland plants were investigated based on a hydroponic experiment (control, 0.8, 1.6 mg As L{sup -1}) and a soil pot trail (control, 60 mg As kg{sup -1}). The results revealed that wetland plants showed great differences in root porosity (9-64%), rates of ROL (55-1750 mmo1 O{sub 2} kg{sup -1} root d.w. d{sup -1}), As uptake (e.g., 8.8-151 mg kg{sup -1} in shoots in 0.8 mg As L{sup -1} treatment), translocation factor (2.1-47% in 0.8 mg As L{sup -1}) and tolerance (29-106% in 0.8 mg As L{sup -1}). Wetland plants with higher rates of ROL and root porosity tended to form more Fe/Mn plaque, possess higher As tolerance, higher concentrations of As on root surfaces and a lower As translocation factor so decreasing As toxicity. - Research highlights: There is significant correlation between the porosity of roots and rates of ROL. The rates of ROL are significantly correlated with tolerance indices and concentrations of As, Fe, Mn on root surface. The rates of ROL is negatively correlated with As translocation factor. - Wetland plants with high rates of ROL tended to form more Fe plaque on root surfaces and possess higher As tolerance.

  15. A porosity-based Biot model for acoustic waves in snow

    OpenAIRE

    Sidler, Rolf

    2015-01-01

    Phase velocities and attenuation in snow can not be explained by the widely used elastic or viscoelastic models for acoustic wave propagation. Instead, Biot's model of wave propagation in porous materials should be used. However, the application of Biot's model is complicated by the large property space of the underlying porous material. Here the properties of ice and air as well as empirical relationships are used to define the properties of snow as a function of porosity. Based on these rel...

  16. Enhanced pyroelectric and piezoelectric properties of PZT with aligned porosity for energy harvesting applications.

    Science.gov (United States)

    Zhang, Yan; Xie, Mengying; Roscow, James; Bao, Yinxiang; Zhou, Kechao; Zhang, Dou; Bowen, Chris R

    2017-04-14

    This paper demonstrates the significant benefits of exploiting highly aligned porosity in piezoelectric and pyroelectric materials for improved energy harvesting performance. Porous lead zirconate (PZT) ceramics with aligned pore channels and varying fractions of porosity were manufactured in a water-based suspension using freeze-casting. The aligned porous PZT ceramics were characterized in detail for both piezoelectric and pyroelectric properties and their energy harvesting performance figures of merit were assessed parallel and perpendicular to the freezing direction. As a result of the introduction of porosity into the ceramic microstructure, high piezoelectric and pyroelectric harvesting figures of merits were achieved for porous freeze-cast PZT compared to dense PZT due to the reduced permittivity and volume specific heat capacity. Experimental results were compared to parallel and series analytical models with good agreement and the PZT with porosity aligned parallel to the freezing direction exhibited the highest piezoelectric and pyroelectric harvesting response; this was a result of the enhanced interconnectivity of the ferroelectric material along the poling direction and reduced fraction of unpoled material that leads to a higher polarization. A complete thermal energy harvesting system, composed of a parallel-aligned PZT harvester element and an AC/DC converter, was successfully demonstrated by charging a storage capacitor. The maximum energy density generated by the 60 vol% porous parallel-connected PZT when subjected to thermal oscillations was 1653 μJ cm(-3), which was 374% higher than that of the dense PZT with an energy density of 446 μJ cm(-3). The results are beneficial for the design and manufacture of high performance porous pyroelectric and piezoelectric materials in devices for energy harvesting and sensor applications.

  17. Probabilistic Open Set Recognition

    Science.gov (United States)

    Jain, Lalit Prithviraj

    Real-world tasks in computer vision, pattern recognition and machine learning often touch upon the open set recognition problem: multi-class recognition with incomplete knowledge of the world and many unknown inputs. An obvious way to approach such problems is to develop a recognition system that thresholds probabilities to reject unknown classes. Traditional rejection techniques are not about the unknown; they are about the uncertain boundary and rejection around that boundary. Thus traditional techniques only represent the "known unknowns". However, a proper open set recognition algorithm is needed to reduce the risk from the "unknown unknowns". This dissertation examines this concept and finds existing probabilistic multi-class recognition approaches are ineffective for true open set recognition. We hypothesize the cause is due to weak adhoc assumptions combined with closed-world assumptions made by existing calibration techniques. Intuitively, if we could accurately model just the positive data for any known class without overfitting, we could reject the large set of unknown classes even under this assumption of incomplete class knowledge. For this, we formulate the problem as one of modeling positive training data by invoking statistical extreme value theory (EVT) near the decision boundary of positive data with respect to negative data. We provide a new algorithm called the PI-SVM for estimating the unnormalized posterior probability of class inclusion. This dissertation also introduces a new open set recognition model called Compact Abating Probability (CAP), where the probability of class membership decreases in value (abates) as points move from known data toward open space. We show that CAP models improve open set recognition for multiple algorithms. Leveraging the CAP formulation, we go on to describe the novel Weibull-calibrated SVM (W-SVM) algorithm, which combines the useful properties of statistical EVT for score calibration with one-class and binary

  18. Shrinkage Porosity Criterion and Its Application to A 5.5 Ton Steel Ingot

    Directory of Open Access Journals (Sweden)

    Zhang C.

    2016-06-01

    Full Text Available In order to predict the distribution of shrinkage porosity in steel ingot efficiently and accurately, a criterion R√L and a method to obtain its threshold value were proposed. The criterion R√L was derived based on the solidification characteristics of steel ingot and pressure gradient in the mushy zone, in which the physical properties, the thermal parameters, the structure of the mushy zone and the secondary dendrite arm spacing were all taken into consideration. The threshold value of the criterion R√L was obtained with combination of numerical simulation of ingot solidification and total solidification shrinkage rate. Prediction of the shrinkage porosity in a 5.5 ton ingot of 2Cr13 steel with criterion R√L>0.21 m · °C1/2 · s−3/2 agreed well with the results of experimental sectioning. Based on this criterion, optimization of the ingot was carried out by decreasing the height-to-diameter ratio and increasing the taper, which successfully eliminated the centreline porosity and further proved the applicability of this criterion.

  19. Prediction of Shrinkage Porosity Defect in Sand Casting Process of LM25

    Science.gov (United States)

    Rathod, Hardik; Dhulia, Jay K.; Maniar, Nirav P.

    2017-08-01

    In the present worldwide and aggressive environment, foundry commercial enterprises need to perform productively with least number of rejections and create casting parts in shortest lead time. It has become extremely difficult for foundry industries to meet demands of defects free casting and meet strict delivery schedules. The process of casting solidification is complex in nature. Prediction of shrinkage defect in metal casting is one of the critical concern in foundries and is one of the potential research areas in casting. Due to increasing pressure to improve quality and to reduce cost, it is very essential to upgrade the level of current methodology used in foundries. In the present research work, prediction methodology of shrinkage porosity defect in sand casting process of LM25 using experimentation and ANSYS is proposed. The objectives successfully achieved are prediction of shrinkage porosity distribution in Al-Si casting and determining effectiveness of investigated function for predicting shrinkage porosity by correlating results of simulating studies to those obtained experimentally. The real-time application of the research reflects from the fact that experimentation is performed on 9 different Y junctions at foundry industry and practical data obtained from experimentation are used for simulation.

  20. Porosity Effect in the Core Thermal Hydraulics for Ultra High Temperature Gas-cooled Reactor

    Directory of Open Access Journals (Sweden)

    Motoo Fumizawa

    2008-12-01

    Full Text Available This study presents an experimental method of porosity evaluation and a predictive thermal-hydraulic analysis with packed spheres in a nuclear reactor core. The porosity experiments were carried out in both a fully shaken state with the closest possible packing and in a state of non-vibration. The predictive analysis considering the fixed porosity value was applied as a design condition for an Ultra High Temperature Reactor Experiment (UHTREX. The thermal-hydraulic computer code was developed and identified as PEBTEMP. The highest outlet coolant temperature of 1316 oC was achieved in the case of an UHTREX at Los Alamos Scientific Laboratory, which was a small scale UHTR. In the present study, the fuel was changed to a pebble type, a porous media. In order to compare the present pebble bed reactor and UHTREX, a calculation based on HTGR-GT300 was carried out in similar conditions with UHTREX; in other words, with an inlet coolant temperature of 871oC, system pressure of 3.45 MPa and power density of 1.3 w/cm3. As a result, the fuel temperature in the present pebble bed reactor showed an extremely lower value compared to that of UHTREX.

  1. UTILIZATION OF AGARWOOD DISTILLATION WASTE IN OILWELL CEMENT AND ITS EFFECT ON FREE WATER AND POROSITY

    Directory of Open Access Journals (Sweden)

    Arina Sauki

    2013-10-01

    Full Text Available The intent of this research is to utilize the waste produced by distillation process of Agarwood oil and convert it into a profitable oilwell cement additive. Common problem during oilwell cementing is free wáter separation. This problem could weaken cement at the top, gas migration problem and non uniform density of cement slurry that are even worst in cementing deviated well. Another concern on cementing design is the porosity of the hardened cement. If the cement is too porous, it can lead to gas migration and casing corrosion. All tests were conducted according to API Specification-10B. Free water test was determined at different concentrations of Agarwood Waste Additive (AWA, different inclination angles and different temperatures. Based on the findings, it was observed that zero free water was produced when 2% BWOC of AWA was used at all angles. The findings also revealed that AWA can maintain good thermal stability as it could maintain zero free water at increased temperature up to 60˚C.  The porosity of AWA cement was comparable with standard API neat cement as the porosity did not differ much at 2% BWOC of AWA. Therefore, it can be concluded that the AWA is suitable to  be used as an additive in oil well cement (OWC  with 2% BWOC is taken as the optimum concentration.

  2. POROSITY AND BAND-STRENGTH MEASUREMENTS OF MULTI-PHASE COMPOSITE ICES

    Energy Technology Data Exchange (ETDEWEB)

    Bossa, Jean-Baptiste; Fransen, Coen; Cazaux, Stéphanie; Linnartz, Harold [Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Maté, Belén; Ortigoso, Juan [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Pilling, Sergio; Rocha, Will Robson Monteiro [Instituto de Pesquisa and Desenvolvimento, Universidade do Vale do Paraiba, São José dos Campos, SP 12244000 (Brazil)

    2015-11-20

    We use experimental mid-infrared optical constants and extended effective medium approximations to determine the porosity and the band strengths of multi-phase composite ices grown at 30 K. A set of porous H{sub 2}O:CH{sub 4} ices are taken as a prototypical example. As a benchmark and proof of concept, the stoichiometry of the ice constituents is retreived with good accuracy from the refractive indices and the extinction coefficients of the reference binary ice mixtures with known compositions. Accurate band strengths are then calculated from experimental mid-infrared spectra of complex ices. We notice that the presence of pores has only a small effect on the overall band strengths, whereas a water dilution can considerably alter them. Different levels of porosity are observed depending on the abundance of methane used as a gas contaminant premixed with water prior to background deposition. The absorption profiles are also found to vary with deposition rate. To explain this, we use Monte Carlo simulations and we observe that the deposition rate strongly affects the pore size distribution as well as the ice morphology through reorganization processes. Extrapolated to genuine interstellar ices, the methodology presented in this paper can be used to evaluate the porosity and to quantify the relative abundances from observational data.

  3. Fabrication of PLLA/β-TCP nanocomposite scaffolds with hierarchical porosity for bone tissue engineering.

    Science.gov (United States)

    Lou, Tao; Wang, Xuejun; Song, Guojun; Gu, Zheng; Yang, Zhen

    2014-08-01

    Polymer and ceramic composite scaffolds play a crucial role in bone tissue engineering. In an attempt to mimic the architecture of natural extracellular matrix (ECM), poly(l-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) nanocomposite scaffolds with a hierarchical pore structure were fabricated by combining thermal induced phase separation and salt leaching techniques. The nanocomposite scaffold consisted of a nanofibrous PLLA matrix with a highly interconnected, high porosity (>93%) hierarchical pore structure with pore diameters ranging from 500nm to 300μm and a homogeneously distributed β-TCP nanoparticle phase. The nanofibrous PLLA matrix had a fiber diameter of 70-300nm. The nanocomposite scaffolds possess three levels of hierarchical structure: (1) porosity; (2) nanofibrous PLLA struts comprising the pore walls; and (3) β-TCP nanoparticle phase. The β-TCP nanoparticle phase improved the mechanical properties and bioactivity of the PLLA matrix. The nanocomposite scaffolds supported MG-63 osteoblast proliferation, penetration, and ECM deposition, indicating the potential of PLLA/β-TCP nanocomposite scaffolds with hierarchical porosity for bone tissue engineering applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Unsaturated Frozen Soil Permeability Coefficient Test and Analysis Under the Condition of Variable Porosity

    Directory of Open Access Journals (Sweden)

    GAO Yu

    2017-06-01

    Full Text Available Frozen soil permeability is one of the key issues in the process of frozen soil water properties research due to special hydrological phenomenon caused by the change of frozen soil water properties. In order to study the effect of ice content and dry density on non - closed porosity and permeability of unsaturated frozen soils, choose ice content ( 2% ,4% ,6% ,8% ,10% ,12% ,14% ,16% ,18% ,20% and dry sample density ( 1. 4 × 103 kg /m3 ,1. 5 × 103 kg /m3 and 1. 6 × 103 kg /m3 as a single variable factor to measure frozen soil permeability coefficient. The water level test method was used to determine the permeability coefficient of frozen soil,and the experimental study on the permeability coefficient of unsaturated frozen soil was carried out. The results show that the permeability coefficient and the unclosed porosity of the unsaturated frozen soil are smaller with the increase of the ice content and dry sample density,and the range is 0. 19 - 0. 714 and 8. 55 - 19. 18 m / d. When the ice content is 20% and the dry density of the sample is 1. 6 × 103 kg /m3 ,the minimum unsaturated permafrost permeability coefficient is 8. 55 m / d and the minimum unclosed porosity is 0. 19.

  5. Effect of hierarchical porosity and phosphorus modification on the catalytic properties of zeolite Y

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenlin; Zheng, Jinyu; Luo, Yibin; Da, Zhijian, E-mail: dazhijian.ripp@sinopec.com

    2016-09-30

    Highlights: • Hierarchical zeolite Y was prepared by citric acid treatment and alkaline treatment with NaOH&TBPH. • The addition of TBPH during desilication process transferred the bridge bonded OH− to the terminal P−OH group. • Moderate Brønsted acid sites could be created with phosphorus modification. • Zeolite with hierarchical porosity and appropriated acidities favored high conversion of 1,3,5-TIPB. - Abstract: The zeolite Y is considered as a leading catalyst for FCC industry. The acidity and porosity modification play important roles in determining the final catalytic properties of zeolite Y. The alkaline treatment of zeolite Y by dealumination and alkaline treatment with NaOH and NaOH&TBPH was investigated. The zeolites were characterized by X-ray diffraction, low-temperature adsorption of nitrogen, transmission electron microscope, NMR, NH{sub 3}-TPD and IR study of acidity. Accordingly, the hierarchical porosity and acidity property were discussed systematically. Finally, the catalytic performance of the zeolites Y was evaluated in the cracking of 1,3,5-TIPB. It was found that desilication with NaOH&TBPH ensured the more uniform intracrystalline mesoporosity with higher microporosity, while preserving higher B/L ratio and moderate Brønsted acidities resulting in catalysts with the most appropriated acidity and then with better catalytic performance.

  6. How burial diagenesis of chalk sediments controls sonic velocity and porosity

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2003-01-01

    Based on P-wave velocity and density data, a new elastic model for chalk sediments is established. The model allows the construction of a series of isoframe (IF) curves, each representing a constant part of the mineral phase contributing to the solid frame. The IF curves can be related to the pro......Based on P-wave velocity and density data, a new elastic model for chalk sediments is established. The model allows the construction of a series of isoframe (IF) curves, each representing a constant part of the mineral phase contributing to the solid frame. The IF curves can be related...... to the progress of burial diagenesis of chalk, which is revised as follows: Newly deposited carbonate ooze and mixed sediments range in porosity from 60 to 80%, depending on the prevalence of hollow microfossils. Despite the high porosity, these sediments are not in suspension, as reflected in IFs of 0.......1 or higher. Upon burial, the sediments lose porosity by mechanical compaction, and concurrently, the calcite particles recrystallize into progressively more equant shapes. High compaction rates may keep the particles in relative motion, whereas low compaction rates allow the formation of contact cement...

  7. Modeling the Effect of Finite-Rate Hydrogen Diffusion on Porosity Formation in Aluminum Alloys

    Science.gov (United States)

    Carlson, Kent D.; Lin, Zhiping; Beckermann, Christoph

    2007-08-01

    A volume-averaged model for finite-rate diffusion of hydrogen in the melt is developed to predict pore formation during the solidification of aluminum alloys. The calculation of the micro-/macro-scale gas species transport in the melt is coupled with a model for the feeding flow and pressure field. The rate of pore growth is shown to be proportional to the local level of gas supersaturation in the melt, as well as various microstructural parameters. Parametric studies of one-dimensional solidification under an imposed temperature gradient and cooling rate illustrate that the model captures important phenomena observed in porosity formation in aluminum alloys. The transition from gas to shrinkage dominated porosity and the effects of different solubilities of hydrogen in the eutectic solid, capillary pressures at pore nucleation, and pore number densities are investigated in detail. Comparisons between predicted porosity percentages and previous experimental measurements show good correspondence, although some uncertainties remain regarding the extent of impingement of solid on the pores.

  8. Porosity Estimation By Artificial Neural Networks Inversion . Application to Algerian South Field

    Science.gov (United States)

    Eladj, Said; Aliouane, Leila; Ouadfeul, Sid-Ali

    2017-04-01

    One of the main geophysicist's current challenge is the discovery and the study of stratigraphic traps, this last is a difficult task and requires a very fine analysis of the seismic data. The seismic data inversion allows obtaining lithological and stratigraphic information for the reservoir characterization . However, when solving the inverse problem we encounter difficult problems such as: Non-existence and non-uniqueness of the solution add to this the instability of the processing algorithm. Therefore, uncertainties in the data and the non-linearity of the relationship between the data and the parameters must be taken seriously. In this case, the artificial intelligence techniques such as Artificial Neural Networks(ANN) is used to resolve this ambiguity, this can be done by integrating different physical properties data which requires a supervised learning methods. In this work, we invert the acoustic impedance 3D seismic cube using the colored inversion method, then, the introduction of the acoustic impedance volume resulting from the first step as an input of based model inversion method allows to calculate the Porosity volume using the Multilayer Perceptron Artificial Neural Network. Application to an Algerian South hydrocarbon field clearly demonstrate the power of the proposed processing technique to predict the porosity for seismic data, obtained results can be used for reserves estimation, permeability prediction, recovery factor and reservoir monitoring. Keywords: Artificial Neural Networks, inversion, non-uniqueness , nonlinear, 3D porosity volume, reservoir characterization .

  9. Editorial: Open Source in Government

    Directory of Open Access Journals (Sweden)

    Dru Lavigne

    2009-04-01

    Full Text Available Last summer, the Center for Strategic and International Studies published the sixth update to their Open Source Policy survey. The survey "tracks governmental policies on the use of open source software as reported in the press or other media." The report lists 275 open source policy initiatives. It also breaks down by country and by government level whether the policy on the use of open source is considered to be advisory, preferential, or mandatory. The editorial theme for the May issue of the OSBR is "open source in government" and we are pleased that the authors have drawn upon their experiences to provide insight into public policy regarding open source for many parts of the world.

  10. Porosity development in the Copper Ridge Dolomite and Maynardville Limestone, Bear Creek Valley and Chestnut Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    Goldstrand, P.M. [Univ. of Nevada, Reno, NV (United States). Geology Dept.; Menefee, L.S. [Appalachian State Univ., Boone, NC (United States). Dept. of Geology; Dreier, R.B. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

    1995-12-01

    Matrix porosity data from deep core obtained in Bear Creek Valley indicate that porosities in the Maynardville Limestone are lithology and depth dependent. Matrix porosities are greater in the Cooper Ridge Dolomite than in the Maynardville Limestone, yet there is no apparent correlation with depth. Two interrelated diagenetic processes are the major controlling factors on porosity development in the Copper Ridge Dolomite and Maynardville Limestone; dissolution of evaporate minerals and dedolomitization. Both of these diagenetic processes produce matrix porosities between 2.1 and 1.3% in the Copper Ridge Dolomite and upper part of the Maynardville Limestone (Zone 6) to depths of approximately 600 ft bgs. Mean matrix porosities in Zones 5 through 2 of the Maynardville Limestone range from 0.8 to 0.5%. A large number of cavities have been intersected during drilling activities in nearly all zones of the Maynardville Limestone in Bear Creek Valley. Therefore, any maynardville Limestone zone within approximately 200 ft of the ground surface is likely to contain cavities that allow significant and rapid flow of groundwater. Zone 6 could be an important stratigraphic unit in the Maynardville Limestone for groundwater flow and contaminant transport because of the abundance of vuggy and moldic porosities. There are large variations in the thickness and lithology in the lower part of the Maynardville (Zones 2, 3, and 4 in the Burial Grounds region). The direction and velocity of strike-parallel groundwater flow may be altered in this area within the lower Maynardville Limestone.

  11. Open architecture CNC system

    Energy Technology Data Exchange (ETDEWEB)

    Tal, J. [Galil Motion Control Inc., Sunnyvale, CA (United States); Lopez, A.; Edwards, J.M. [Los Alamos National Lab., NM (United States)

    1995-04-01

    In this paper, an alternative solution to the traditional CNC machine tool controller has been introduced. Software and hardware modules have been described and their incorporation in a CNC control system has been outlined. This type of CNC machine tool controller demonstrates that technology is accessible and can be readily implemented into an open architecture machine tool controller. Benefit to the user is greater controller flexibility, while being economically achievable. PC based, motion as well as non-motion features will provide flexibility through a Windows environment. Up-grading this type of controller system through software revisions will keep the machine tool in a competitive state with minimal effort. Software and hardware modules are mass produced permitting competitive procurement and incorporation. Open architecture CNC systems provide diagnostics thus enhancing maintainability, and machine tool up-time. A major concern of traditional CNC systems has been operator training time. Training time can be greatly minimized by making use of Windows environment features.

  12. Opening Address

    Science.gov (United States)

    Yamada, T.

    2014-12-01

    Ladies and Gentlemen, it is my great honor and pleasure to present an opening address of the 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"(SOTANCP3). On the behalf of the organizing committee, I certainly welcome all your visits to KGU Kannai Media Center belonging to Kanto Gakuin University, and stay in Yokohama. In particular, to whom come from abroad more than 17 countries, I would appreciate your participations after long long trips from your homeland to Yokohama. The first international workshop on "State of the Art in Nuclear Cluster Physics", called SOTANCP, was held in Strasbourg, France, in 2008, and the second one was held in Brussels, Belgium, in 2010. Then the third workshop is now held in Yokohama. In this period, we had the traditional 10th cluster conference in Debrecen, Hungary, in 2012. Thus we have the traditional cluster conference and SOTANCP, one after another, every two years. This obviously shows our field of nuclear cluster physics is very active and flourishing. It is for the first time in about 10 years to hold the international workshop on nuclear cluster physics in Japan, because the last cluster conference held in Japan was in Nara in 2003, about 10 years ago. The president in Nara conference was Prof. K. Ikeda, and the chairpersons were Prof. H. Horiuchi and Prof. I. Tanihata. I think, quite a lot of persons in this room had participated at the Nara conference. Since then, about ten years passed. So, this workshop has profound significance for our Japanese colleagues. The subjects of this workshop are to discuss "the state of the art in nuclear cluster physics" and also discuss the prospect of this field. In a couple of years, we saw significant progresses of this field both in theory and in experiment, which have brought better and new understandings on the clustering aspects in stable and unstable nuclei. I think, the concept of clustering has been more important than ever. This is true also in the

  13. Open Standards, Open Source, and Open Innovation: Harnessing the Benefits of Openness

    Science.gov (United States)

    Committee for Economic Development, 2006

    2006-01-01

    Digitization of information and the Internet have profoundly expanded the capacity for openness. This report details the benefits of openness in three areas--open standards, open-source software, and open innovation--and examines the major issues in the debate over whether openness should be encouraged or not. The report explains each of these…

  14. OpenEIS. Users Guide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woohyun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lutes, Robert G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Katipamula, Srinivas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Haack, Jereme N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carpenter, Brandon J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Akyol, Bora A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Monson, Kyle E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Allwardt, Craig H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kang, Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sharma, Poorva [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-02-28

    This document is a users guide for OpenEIS, a software code designed to provide standard methods for authoring, sharing, testing, using and improving algorithms for operational building energy efficiency.

  15. 4D porosity evolution during solid-solid replacement reaction in mineral system (KBr, KCl)

    Science.gov (United States)

    Beaudoin, Nicolas; Hamilton, Andrea; Koehn, Daniel; Shipton, Zoe

    2017-04-01

    An extensive understanding of the controlling mechanisms of phase transformation is key in geosciences to better predicting the evolution of the physical parameters of rocks (porosity, permeability, and rheology) from centimetre-scale (e.g. fingering in siltstones) to kilometer-scale (e.g. Dolostone geobodies), in both the diagenetic and metamorphic domains. This contribution reports the 4D monitoring of a KBr crystal at different time steps during an experimental, fluid-mediated replacement reaction with KCl. Volumes are reconstructed based on density contrast using non-destructive X-ray Computed Tomography (XCT) at a resolution of 3 microns. A sample of KBr was immersed in a static bath of saturated KCl at room temperature and pressure. 5 scans were performed during the reaction at 5, 10, 20, 35 and 55 minutes, until 50% of the original crystal was replaced. As a control experiment, two samples reacted continuously for 15 and 55 minutes, respectively. Each 3D dataset was reconstructed to visualize and quantify the different mineral phases, the porosity distribution and connectivity, along with the reaction front morphology. In the case of successive baths, results show that the front morphology evolves from rough with small fingers to flat and thick during the reaction, suggesting a switch between advection and diffusion controlled reactant distribution through time. This switch is also reflected in the mass evolution and the rate of propagation of the replaced zone, being rapid in the first 20 minutes before reaching steady state. The porosity develops perpendicular to the crystal wall, suggesting a self-organization process governed by advection, before connecting laterally. While the reaction changes from advection controlled to diffusion controlled, the direction of the connected pores becomes parallel to the crystal walls. This phenomenon is not observed when the crystal is reacting discontinuously for 55 minutes. In the latter case, self

  16. Porosity, Mineralization, Tissue Type and Morphology Interactions at the Human Tibial Cortex

    Science.gov (United States)

    Hampson, Naomi A.

    Prior research has shown a relationship between tibia robustness (ratio of cross-sectional area to bone length) and stress fracture risk, with less robust bones having a higher risk, which may indicate a compensatory increase in elastic modulus to increase bending strength. Previous studies of human tibiae have shown higher ash content in slender bones. In this study, the relationships between variations in volumetric porosity, ash content, tissue mineral density, secondary bone tissue, and cross sectional geometry, were investigated in order to better understand the tissue level adaptations that may occur in the establishment of cross-sectional properties. In this research, significant differences were found between porosity, ash content, and tissue type around the cortex between robust and slender bones, suggesting that there was a level of co-adaption occurring. Variation in porosity correlated with robustness, and explained large parts of the variation in tissue mineral density. The nonlinear relationship between porosity and ash content may support that slender bones compensate for poor geometry by increasing ash content through reduced remodeling, while robust individuals increase porosity to decrease mass, but only to a point. These results suggest that tissue level organization plays a compensatory role in the establishment of adult bone mass, and may contribute to differences in bone aging between different bone phenotypes. The results suggest that slender individuals have significantly less remodeled bone, however the proportion of remodeled bone was not uniform around the tibia. In the complex results of the study of 38% vs. 66% sites the distal site was subject to higher strains than the 66% site, indicating both local and global regulators may be affecting overall remodeling rates and need to be teased apart in future studies. This research has broad clinical implications on the diagnosis and treatment of fragility fractures. The relationships that

  17. Fusion zone microstructure and porosity in electron beam welds of an α+β titanium alloy

    Science.gov (United States)

    Mohandas, T.; Banerjee, D.; Kutumba Rao, V. V.

    1999-03-01

    The effect of electron beam welding parameters on fusion zone (FZ) microstructure and porosity in a Ti -6.8 Al -3.42 Mo -1.9 Zr -0.21 Si alloy (Russian designation VT 9) has been investigated. It has been observed that the FZ grain width increased continuously with increase in heat input when the base metal was in the β heat-treated condition, while in the α+β heat-treated base metal welds, the FZ grain width increased only after a threshold energy input. The difference is attributed to both the weld thermal cycle and the pinning effect of equiaxed primary alpha on grain growth in the heat-affected zone (HAZ) of α+β heat-treated base metal. Postweld heat treatment (PWHT) in the subtransus and supertransus regions did not alter the columnar grain morphology in the FZ, possibly due to the lack of enough driving force for the formation of new grains by the breaking up of the columnar grains and grain boundary movement for grain growth. As the PWHTs were conducted in a furnace, the role of thermal gradients can be ruled out. Intragranular microstructure in the aswelded condition consisted of hexagonal martensite. The scale of the martensite laths depended on welding speed. The highest porosity was observed at intermediate welding speeds. At low speeds, a majority of pores formed at the fusion boundary, while at high speeds, occurrence of porosity was maximum at the weld center. The trends on porosity can be explained on the basis of solubility of hydrogen in titanium as a function of temperature and the influence of weld thermal cycle on nucleation, growth, and escape of hydrogen gas bubbles. The porosity at slow welding speeds is low because sufficient time exists for the nucleation, growth, and escape of hydrogen gas bubbles, while insufficient time exists for the nucleation of gas bubbles at high welding speeds. The effect of pickling of joint surface, vacuum annealing of the base metal, and successive remelting of the weld metal has also been investigated.

  18. Nested Open Books And The Binding Sum

    OpenAIRE

    Durst, Sebastian; Klukas, Mirko

    2016-01-01

    We introduce the notion of a \\emph{nested open book}, a submanifold equipped with an open book structure compatible with an ambient open book, and describe in detail the special case of a \\emph{push-off} of the binding of an open book. This enables us to explicitly describe a natural open book decomposition of a fibre connected sum of two open books along their bindings, provided they are diffeomorphic and admit an open book structure themselves. Furthermore, we apply the results to contact o...

  19. Use of SEM and EDS analysis in the investigation of Al-Si-Cu piston alloy cast porosity

    Directory of Open Access Journals (Sweden)

    D. Kakaš

    2009-07-01

    Full Text Available Porosity formation was detected in the casting thinnest section in the proximity of the as cast surface and near the wall centerline. In order to investigate the cause of the porosity formation light microscopy was used to define as cast structure. After initial findings SEM and EDS analyses were performed. Based on the results it is possible to define cause of the observed porosity. A number of pores originates from the mould filling stage and entrainment of the oxide films, while others appear due to insufficient feeding during solidification.

  20. Electrochemical impedance spectroscopy and linear polarization applied to evaluation of porosity of phosphate conversion coatings on electrogalvanized steels

    Science.gov (United States)

    de Freitas Cunha Lins, Vanessa; de Andrade Reis, Geraldo Francisco; de Araujo, Carlos Roberto; Matencio, Tulio

    2006-12-01

    In this work, electrochemical impedance spectroscopy and linear polarization are used in determining porosity of zinc phosphates, and of nickel and manganese modified zinc phosphates on electrogalvanized steel. The porosity of the phosphate layers ranges from 0.1% for the manganese-modified hopeite to 8% for hopeite, using the linear polarization and the electrochemical impedance spectroscopy techniques. The porosity values measured using the two techniques were in agreement. All impedance spectra of coated samples showed two steps, with two capacitive arcs and an inductive looping.

  1. Quantification of porosity evolution from unaltered to propylitic-altered granites: the 14C-PMMA method applied on the hydrothermal system of Lavras do Sul, Brazil

    Directory of Open Access Journals (Sweden)

    Everton M. Bongiolo

    2007-09-01

    Full Text Available This work is an application of the 14C-Polymethylmethacrylate method to compare the porosity evolution between unaltered and propylitic-altered granites, using samples from Lavras do Sul region, Brazil. This method, when coupled with optical and electronic petrography has the advantage over other methods to provide the quantification and identification of total and local porosity of rocks. From petrographic observations, different kinds of porous zones were identified and quantified (microfractures, grain boundaries, alteration of minerals, etc. Results show that unaltered granites have 0.5 to 0.6% porosity and propylitic-altered ones have 1.7 to 1.8% porosity, even between samples with different textures. Porosity of altered rocks increases mainly due to higher porosity of neoformed chlorite, calcite, sericite and microfractures. Field observations show that later phyllic alteration halos are wider in equigranular than in porphyritic granites, which could not be explained by different original porosity between those rocks. The observed differences of phyllic halos diffusion were controlled by structural and fluid/rock ratio variations between the equigranular and porphyritic granitic facies during the later hydrothermal stage.Este trabalho é uma aplicação do método 14C-polimetilmetacrilato na comparação da evolução da porosidade entre granitos não alterados e propilitizados, utilizando amostras da região de Lavras do Sul, Brasil. Este método, quando associado a análises por petrografia ótica, eletrônica e processamento digital de imagens tem a vantagem de fornecer, além da porosidade total, a quantificação e identificação da porosidade em locais específicos das rochas. A partir da petrografia foi possível identificar e quantificar os diferentes tipos de poros presentes nas rochas (microfraturas, limites de grãos, alteração de minerais, etc. Os resultados mostram que granitos não alterados têm porosidade de 0,5 a 0,6% e

  2. Open-Source Colorimeter

    Science.gov (United States)

    Anzalone, Gerald C.; Glover, Alexandra G.; Pearce, Joshua M.

    2013-01-01

    The high cost of what have historically been sophisticated research-related sensors and tools has limited their adoption to a relatively small group of well-funded researchers. This paper provides a methodology for applying an open-source approach to design and development of a colorimeter. A 3-D printable, open-source colorimeter utilizing only open-source hardware and software solutions and readily available discrete components is discussed and its performance compared to a commercial portable colorimeter. Performance is evaluated with commercial vials prepared for the closed reflux chemical oxygen demand (COD) method. This approach reduced the cost of reliable closed reflux COD by two orders of magnitude making it an economic alternative for the vast majority of potential users. The open-source colorimeter demonstrated good reproducibility and serves as a platform for further development and derivation of the design for other, similar purposes such as nephelometry. This approach promises unprecedented access to sophisticated instrumentation based on low-cost sensors by those most in need of it, under-developed and developing world laboratories. PMID:23604032

  3. Open Interiors for Efficiency and Conservation

    Science.gov (United States)

    Modern Schools, 1974

    1974-01-01

    Open plan interiors in school design provide excellent opportunities for cutting costs by optimizing in construction and electric comfort conditioning. Important considerations to keep in mind when planning for the open concept. (Author)

  4. The Open Science Grid

    CERN Document Server

    Pordes, Ruth; Olson, Doug; Livny, Miron; Roy, Alain; Avery, Paul; Blackburn, Kent; Wenaus, Torre; Wuerthwein, Frank K.; Gardner, Rob; Wilde, Mike; Blatecky, Alan; McGee, John; Quick, Rob

    2007-01-01

    The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. OSG provides support for and evolution of the infrastructure through activities that cover operations, security, software, troubleshooting, addition of new capabilities, and support for existing and engagement with new communities. The OSG SciDAC-2 project provides specific activities to manage and evolve the distributed infrastructure and support it's use. The innovative aspects of the project are the maintenance and performance of a collaborative (shared & common) petascale national facility over tens of autonomous computing sites, for many hundreds of users, transferring terabytes of data a day, executing tens of thousands of jobs a day, and providing robust and usable resources for scientific groups of all types and sizes. More information can be found at the OSG web site: www.opensciencegrid.org.

  5. The Open Science Grid

    Energy Technology Data Exchange (ETDEWEB)

    Pordes, Ruth; /Fermilab; Kramer, Bill; Olson, Doug; / /LBL, Berkeley; Livny, Miron; Roy, Alain; /Wisconsin U., Madison; Avery, Paul; /Florida U.; Blackburn, Kent; /Caltech; Wenaus, Torre; /Brookhaven; Wurthwein, Frank; /UC, San Diego; Gardner, Rob; Wilde, Mike; /Chicago U. /Indiana U.

    2007-06-01

    The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. OSG provides support for and evolution of the infrastructure through activities that cover operations, security, software, troubleshooting, addition of new capabilities, and support for existing and engagement with new communities. The OSG SciDAC-2 project provides specific activities to manage and evolve the distributed infrastructure and support its use. The innovative aspects of the project are the maintenance and performance of a collaborative (shared & common) petascale national facility over tens of autonomous computing sites, for many hundreds of users, transferring terabytes of data a day, executing tens of thousands of jobs a day, and providing robust and usable resources for scientific groups of all types and sizes. More information can be found at the OSG web site: www.opensciencegrid.org.

  6. Extracting porosity and modelling permeability from μCT and FIB-SEM data of fractured dolomites from a hydrocarbon reservoir

    Science.gov (United States)

    Voorn, M. H.; Rath, A.; Exner, U.

    2012-04-01

    Currently oil and gas in the Vienna Basin are produced partly from the Upper Triassic Hauptdolomit formation. Various drill-cores were retrieved from densely fractured dolomites from depths between 3000 and 5300 m. Porosity and permeability assessment in specimen from such fractured rocks proves to be difficult by common laboratory methods, and also 2D sample analysis alone is insufficient to this end. In our study, X-ray micro-Computed Tomography (µCT) is used to visualise the inside of core samples of fractured Hauptdolomit. The biggest advantage of µCT is that it provides a 3D view of the fractures and other porosity, without destroying the sample. Core sample descriptions, 2D thin section analysis and standard laboratory measurements are used for extended analysis and cross-calibration of the results. In addition, 3D porosity visualisations at the micro- to nano-scale are obtained from Focussed Ion Beam - Scanning Electron Microscopy (FIB-SEM) on thin sections. The narrow fractures encountered in the Hauptdolomit samples require sufficient resolution µCT scans (i.e. better than ca. 25 µm). Full 10 cm diameter cores of sample prove to be too thick and dense, so that the fracture network cannot be recorded properly. 3 cm sized plugs on the other hand do provide workable results. After obtaining good datasets, the fractures need to be segmented (separated) from the full dataset for further analysis. A large amount of different segmentation routines is available from literature, but very little are applicable for segmenting narrow fractures, especially not in geological literature. Our current best results stem from applying the so-called "Frangi filter" used in segmentation routines in the medical sciences for segmenting blood vessels. After this segmentation, the fracture patterns can be extracted, and quantitative analysis of the bulk porosity and porosity distribution, fracture aperture and length can be performed. The data obtained by FIB-SEM is treated in

  7. CJEP will offer open science badges.

    Science.gov (United States)

    Pexman, Penny M

    2017-03-01

    This editorial announces the decision of the Canadian Journal of Experimental Psychology (CJEP) to offer Open Science Framework (OSF) Badges. The Centre for Open Science provides tools to facilitate open science practices. These include the OSF badges. The badges acknowledge papers that meet standards for openness of data, methods, or research process. They are now described in the CJEP Submission Guidelines, and are provided in the editorial. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  8. Influence of Powder Characteristics on Formation of Porosity in Additive Manufacturing of Ti-6Al-4V Components

    Science.gov (United States)

    Iebba, Maurizio; Astarita, Antonello; Mistretta, Daniela; Colonna, Ivano; Liberini, Mariacira; Scherillo, Fabio; Pirozzi, Carmine; Borrelli, Rosario; Franchitti, Stefania; Squillace, Antonino

    2017-08-01

    This paper aims to study the genesis of defects in titanium components made through two different additive manufacturing technologies: selective laser melting and electron beam melting. In particular, we focussed on the influence of the powders used on the formation of porosities and cavities in the manufactured components. A detailed experimental campaign was carried out to characterize the components made through the two additive manufacturing techniques aforementioned and the powders used in the process. It was found that some defects of the final components can be attributed to internal porosities of the powders used in the manufacturing process. These internal porosities are a consequence of the gas atomization process used for the production of the powders themselves. Therefore, the importance of using tailored powders, free from porosities, in order to manufacture components with high mechanical properties is highlighted.

  9. Comparative analysis of rock porosity in a selected region in the Carpathians based on laboratory data and well logs

    Directory of Open Access Journals (Sweden)

    Barnaś Maciej

    2017-01-01

    Full Text Available A comparative analysis of porosity is presented in the article. This was calculated from laboratory measurements and well logs for rocks from a selected region of the Carpathians. Analysis was performed for samples of sandstones, mudstones, shales and carbonates from four boreholes drilled in the Carpathian Foredeep region near Krakow, Poland. In laboratory measurements, porosity was assessed using two methods: helium pycnometry and nuclear magnetic resonance (NMR. Porosity from well logging was calculated from sonic profiling (SPHI. Cross-plots were used, which allowed for the assessment of the degree of correlation between the laboratory and well log data. The results obtained were analysed paying special attention to the relationship with geological structure. Based on the lithological criterion, the correlations turned out to be strong. The repeatability of the results obtained in different wells was verified. The results of the measurements are significant in relation to estimating porosity from well logs using laboratory data.

  10. Porosity measurement of amorphous materials by gamma ray transmission; Medida de porosidade de materiais amorfos por transmissao de raios gama

    Energy Technology Data Exchange (ETDEWEB)

    Poettker, Walmir Eno

    2000-07-01

    In this work it is presented the measurement of the total porosity of TRe soil, Sandstone Berea rocks and porous ceramics samples. For the determination of the total porosity, the Arquimedes method (conventional) and the gamma ray transmission methodology were employed. The porosity measurement using the gamma methodology has a significant advantage respect to the conventional method due to the fast and non-destructive determination, and also for supplying results with a greater characterization in small scales, in relation to the heterogeneity of the porosity. The conventional methodology presents good results only for homogeneous samples. The experimental set up for the gamma ray transmission technique consisted of a {sup 241} Am source (59,53 keV), a NaI (Tl) scintillation detector, collimators, a XYZ, micrometric table and standard gamma spectrometry electronics connected to a multichannel analyser. (author)

  11. Comparative analysis of rock porosity in a selected region in the Carpathians based on laboratory data and well logs

    Science.gov (United States)

    Barnaś, Maciej; Puskarczyk, Edyta

    2017-11-01

    A comparative analysis of porosity is presented in the article. This was calculated from laboratory measurements and well logs for rocks from a selected region of the Carpathians. Analysis was performed for samples of sandstones, mudstones, shales and carbonates from four boreholes drilled in the Carpathian Foredeep region near Krakow, Poland. In laboratory measurements, porosity was assessed using two methods: helium pycnometry and nuclear magnetic resonance (NMR). Porosity from well logging was calculated from sonic profiling (SPHI). Cross-plots were used, which allowed for the assessment of the degree of correlation between the laboratory and well log data. The results obtained were analysed paying special attention to the relationship with geological structure. Based on the lithological criterion, the correlations turned out to be strong. The repeatability of the results obtained in different wells was verified. The results of the measurements are significant in relation to estimating porosity from well logs using laboratory data.

  12. Effective porosity and pore-throat sizes of Conasauga Group mudrock: Application, test and evaluation of petrophysical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Dorsch, J. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.; Katsube, T.J. [Geological Survey of Canada, Ottawa, Ontario (Canada). Mineral Resources Div.; Sanford, W.E. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.]|[Univ. of Tennessee, Knoxville, TN (United States). Dept. of Civil and Environmental Engineering; Dugan, B.E. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Civil and Mineral Engineering; Tourkow, L.M. [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth and Atmospheric Sciences

    1996-04-01

    Effective porosity (specifically referring to the interconnected pore space) was recently recognized as being essential in determining the effectiveness and extent of matrix diffusion as a transport mechanism within fractured low-permeability rock formations. The research presented in this report was performed to test the applicability of several petrophysical techniques for the determination of effective porosity of fine-grained siliciclastic rocks. In addition, the aim was to gather quantitative data on the effective porosity of Conasauga Group mudrock from the Oak Ridge Reservation (ORR). The quantitative data reported here include not only effective porosities based on diverse measurement techniques, but also data on the sizes of pore throats and their distribution, and specimen bulk and grain densities. The petrophysical techniques employed include the immersion-saturation method, mercury and helium porosimetry, and the radial diffusion-cell method.

  13. Room temperature air oxidation of nanostructured Si thin films with varying porosities as studied by x-ray photoelectron spectroscopy

    Science.gov (United States)

    Yang, D.-Q.; Meunier, M.; Sacher, E.

    2006-04-01

    The room temperature air oxidation of nanostructured Si thin films, with varying porosities, has been followed by x-ray photoelectron spectroscopy (XPS), using films deposited by KrF excimer (248 nm) laser ablation in He gas ambients. The overall oxidation, determined from the Si2p XPS spectrum, was shown to be amenable to time-porosity superposition, with the extracted shift factors indicating that oxidation is controlled by the permeability of air in the pores. A model has been developed to describe the room temperature air oxidation process as a function of time and porosity, in accord with the experimental findings. Efforts to determine O:Si atomic ratios from O1s:Si2p spectral ratios have revealed the effect of porosity on both the photoelectron attenuation lengths and the size-dependent photoemission intensities of the nanoparticles that compose the samples.

  14. Open Achilles tendon lacerations.

    Science.gov (United States)

    Said, M Nader; Al Ateeq Al Dosari, Mohamed; Al Subaii, Nasser; Kawas, Alaa; Al Mas, Ali; Al Ser, Yaser; Abuodeh, Yousef; Shakil, Malik; Habash, Ali; Mukhter, Khalid

    2015-04-01

    In contrast to closed Achilles tendon ruptures, open injuries are rarely reported in the literature. This paper provides information about open Achilles tendon wounds that are eventually seen in the Middle East. The reporting unit, Hamad Medical Corporation, is one of the biggest trauma centers in the Gulf area and the major health provider in Qatar. This is a retrospective study including patients admitted and operated for open Achilles tendon injuries between January 2011 and December 2013. Two hundred and five cases of open Achilles tendon lacerations were operated in Hamad General Hospital in this period. Forty-eight cases showed partial injuries, and the remaining are complete tendons cut. In the same period, fifty-one closed ruptured Achilles tendons were operated in the same trauma unit. In the majority of cases, the open injury resulted from a slip in the floor-leveled traditional toilette seats. Local damage to the toilette seats resulted in sharp edges causing the laceration of the heel if the patient was slipping over the wet floor. This occurrence is the cause in the vast majority of the cases. Wounds were located 1-5 cm proximal to tendon insertion. Standard treatment principles were applied. This included thorough irrigation in the emergency room, intravenous antibiotics, surgical debridement and primary repair within 24 h. Patients were kept in the hospital 1-7 days for intravenous antibiotics and possible dressing changes. Postoperatively below knee slabs were applied in the majority of patients and were kept for about 4 weeks followed by gradual weight bearing and range of motion exercises. Outpatients follow up in 1-2 weeks. Further follow-up visits at around 2-, 4-, 8- and 12-week intervals until complete wound healing and satisfactory rehabilitation outcome. Sixteen cases needed a second procedure. A high incidence of Achilles tendon open injuries is reported. This seems to be related to partially damaged floor-level toilettes in the

  15. From Open Source to Open Collaboration

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Open source is the right to modify, not the right to contribute. Are external contributions absent from your project? Have you ever thought about what is it like to be a new contributor on your project? I challenge you to transform your project from Open Source to an Open Collaboration.

  16. The effect of activation agent on surface morphology, density and porosity of palm shell and coconut shell activated carbon

    Science.gov (United States)

    Leman, A. M.; Zakaria, S.; Salleh, M. N. M.; Sunar, N. M.; Feriyanto, D.; Nazri, A. A.

    2017-09-01

    Activated carbon (AC) has one of the promising alternative technology for filtration and adsorption process. It inexpensive material because the sources is abundant especially in Malaysia. Main purpose of this project is to develop AC by chemical activation process to improve adsorption capacity by improving porosity of AC. AC developed via carbonization using designed burner at temperature of 650°C to 850 °C and activated by Potassium Hydroxide (KOH) in 12 hour and then dried at temperature of 300°C. Characterization and analysis is conducted by Scanning Electron Microscopy (SEM) for surface morphology analysis, Energy Dispersive Spectroscopy (EDS) for composition analysis, density and porosity analysis. Results shows that uneven surface has been observed both of AC and non-AC and also AC shows higher porosity as compared to non-AC materials. Density value of raw material has lower than AC up to 11.67% and 47.54% and porosity of raw material has higher than AC up to 31.45% and 45.69% for palm shell and coconut shell AC. It can be concluded that lower density represent higher porosity of material and higher porosity indicated higher adsorption capacity as well.

  17. Influence of withdrawal rate on the porosity in a third-generation Ni-based single crystal superalloy

    Directory of Open Access Journals (Sweden)

    Quanzhao Yue

    2017-04-01

    Full Text Available The influence of withdrawal rate on the porosity in a third-generation Ni-based single crystal superalloy was investigated by a quantitative evaluation method. The results showed that the withdrawal rate obviously effected on the average area fraction, number and diameter of porosities except their radius ratios. In consideration of the microstructure observation for dendrite arms, an optimized withdrawal rate was obtained with a minimum porosity level as about 125 µm s−1. Simultaneously, a threshold value for the acceptance level of porosities might be set as about 0.1% in order to fulfill the requirements for Ni-based single crystal casting in laboratory scale. Finally, the formation reason of porosity was discussed and it was concluded that the feeding for the volume shrinkage of the last solidified eutectic liquids from the residual liquids and the isolating effect of the morphologies of dendrite arms might be two key factors in controlling the porosities level in Ni-based single crystal superalloy.

  18. Fuzzy model to predict porosity thought conventional well logs; Modelo Fuzzy para predicao de porosidade via perfis convencionais de poco

    Energy Technology Data Exchange (ETDEWEB)

    Mimbela, Renzo R.F.; Silva, Jadir C. [Universidade Estadual do Norte Fluminense (UENF), Macae, RJ (Brazil). Lab. de Engenharia e Exploracao do Petroleo (LENEP)

    2004-07-01

    The well logs have a great applicability in the search and evaluation of hydrocarbon. In this work we calculate porosities of the Namorado field with help of the 'Fuzzy Rule'. This is done segmenting jointly both the neutron ({phi}{sub N}) and density ({phi}{sub d}) porosities logs in groups with better relation of internal linearity. The grouping is processed keeping the best number of groups, which is efficiently chosen by a criterion related to the minimum value of 'Fuzzy Validity' measurement. As a first step, we choose the {phi}{sub N} and {phi}{sub d} values only at that depths where cores exist. To prevent picking measurements errors a previous data filtering is performed by selecting only the and their correspondent values that exhibit a maximum discrepancy with core porosity ({phi}{sub C}) around 5pu (porosity unit). A conventional average porosity {phi}{sub MED}, mixing {phi}{sub N} and {phi}{sub d} is calculated at each point, concerning its own lithological and fluids characteristics. Finally, an inversion algorithm is applied to indicate the best curve curve that fit linearly {phi}{sub C} vs. {phi}{sub MED}, {phi}{sub C} vs. {phi}{sub D} and {phi}{sub C} vs. {phi}{sub N}, and at the same time determines the values of the constants to be extrapolated in order to calculate the porosity of the whole field. (author)

  19. Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

    Directory of Open Access Journals (Sweden)

    Lihua Zuo

    2017-01-01

    Full Text Available Porous media like hydrocarbon reservoirs may be composed of a wide variety of rocks with different porosity and permeability. Our study shows in algorithms and in synthetic numerical simulations that the flow pattern of any particular porous medium, assuming constant fluid properties and standardized boundary and initial conditions, is not affected by any spatial porosity changes but will vary only according to spatial permeability changes. In contrast, the time of flight along the streamline will be affected by both the permeability and porosity, albeit in opposite directions. A theoretical framework is presented with evidence from flow visualizations. A series of strategically chosen streamline simulations, including systematic spatial variations of porosity and permeability, visualizes the respective effects on the flight path and time of flight. Two practical rules are formulated. Rule  1 states that an increase in permeability decreases the time of flight, whereas an increase in porosity increases the time of flight. Rule  2 states that the permeability uniquely controls the flight path of fluid flow in porous media; local porosity variations do not affect the streamline path. The two rules are essential for understanding fluid transport mechanisms, and their rigorous validation therefore is merited.

  20. Black bears with longer disuse (hibernation) periods have lower femoral osteon population density and greater mineralization and intracortical porosity.

    Science.gov (United States)

    Wojda, Samantha J; Weyland, David R; Gray, Sarah K; McGee-Lawrence, Meghan E; Drummer, Thomas D; Donahue, Seth W

    2013-08-01

    Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans. Copyright © 2013 Wiley Periodicals, Inc.