2,591 research outputs found
2D Soil Springs for Elastic Settlements of Mat Foundation under Vertically Uniform Loads
No full textThis paper intends to introduce a two-dimensional soil spring model that can be used to predict the settlements of a mat under uniformly vertical loads. The model was incorporated into a two dimensional numerical analysis of the mat settlements using FD method. Solutions comparable to 3D FEM analysis will be presented.補正完
Het creëren van een vastgoedportfolio in de beleveniseconomie; over een mogelijke toekomst van vastgoedmanagement
No full textIn het onderzoek wordt gezocht naar een verband tussen ontwikkelingen in de economie en filosofie en veranderingen in het vakgebied vastgoedmanagement. Het resultaat van dit onderzoek is een model dat verwachtingen beschrijft hoe organisaties in de toekomst in de beleveniseconomie een vastgoedportfolio zullen gaan creëren. Beleveniseconomie is het fenomeen van een verschuiving van aandacht in de economie op drie thema's: de toename van de waardering van de immateriële aspect, de actievere rol van de klant in het creëren van de belevenis en de toename van de individualiteit van de belevenis. De Nederlandse filosoof Arnold Cornelis beschrijft in zijn boek "Logica van het gevoel" eenzelfde soort verschuiving van aandacht. Echter richt hij zich niet op de economie, maar op mens en maatschappij als geheel: een hoger abstractieniveau. Hij beschrijft dat mens en maatschappij in een transitie leven van het sociaal regelsysteem naar communicatieve zelfsturing. In het sociaal regelsysteem, zo beschrijft Cornelis, wordt veel waarde gehecht aan feiten, materiële en wetenschappelijke aspecten van de werkelijkheid. Mensen zoeken naar een vervulling van materiële behoeften en het individu wordt gestuurd door de buitenwereld, de mens wordt gevormd door de cultuur. Het individu neemt een passieve rol aan. Een communicatief zelfsturend individu hecht veel waarde aan persoonlijke waarden, het niet tast-bastbare innerlijke van de mens. Een communicatief zelfsturend individu is in staat haar eigen cultuur te vormen door communicatie op een gelijkwaardige basis. Het volgt niet zwijgzaam alle regels op die de individu van buitenaf krijgt opgelegd, maar gaat in discussie over het "waarom". Op zowel economisch gebied als in de mens en maatschappij is dus sprake van een transformatie. In de oude systemen wordt veel aandacht wordt gehecht aan materiele zaken en feiten, vindt weinig communicatie op een gelijkwaardige basis plaats en de mens en maatschappij worden gevormd door de regels die van buitenaf worden opgelegd. Het nieuwe systeem kenmerkt zich door communicatie op een gelijkwaardige basis met alle partijen, er wordt veel waarde gehecht aan persoonlijke waarden en de mens begint weer haar eigen cultuur te vormen in plaats van andersom. In vastgoedmanagement wordt ook veel waarde gehecht aan feiten en materialistische zaken, zo blijkt uit een intensieve literatuurstudie. Ook blijkt uit die studie dat er weinig aandacht lijkt voor communicatie. Maar enkele case studies, waarin bedrijven zijn onderzocht die vooruitstrevend zijn in de beleveniseconomie, tonen aan dat binnen die bedrijven de manier waarop vastgoedmanagement bedreven wordt overeenkomt met de kenmerken van de beleveniseconomie en het communicatief zelfsturend systeem. Aan de hand van deze nieuwe theoretische en praktische kennis is het "Model voor het creëren van een vastgoedportfolio met Mensen" ontworpen. Dit model geeft dus aan wat de verwachtingen zijn van de kernpunten van vastgoedmanagement in de toekomst. Wanneer deze verschuiving binnen het vastgoedmanagement precies plaats zal gaan plaatsvinden is onbekend. Het is ook niet gegarandeerd dat deze verschuiving precies op deze manier plaats zal gaan vinden. Het "Model voor het Creëren van een Vastgoedportfolio met Mensen" kan voor de vastgoedmanager die geïnteresseerd is in deze theorie een leidraad en inspiratiebron zijn om in zijn werk toe te passen. -Cornelis, A., Logica van het gevoel, stabiliteitslagen in de cultuur als nesteling der emoties, 1993, Amsterdam / Brussel / Middelburg, Uitgave Stichting Essence, 747 pag., ISBN 90-72258-02-9Architectur
Author Correction: New perspectives on Neanderthal dispersal and turnover from Stajnia Cave (Poland)
Get PDFThe Author contributions section now reads:“W.N., A.N. and S.T. designed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. performed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. analysed data; A.P., M.H., S.T., W.N. and S.B. wrote the paper with the collaboration of all the co-authors.
Announcement of the National Academy of Science's establishment of an office at Camp Kilmer
No full textAfter the Soviets suppressed the Revolution in Hungary in 1956, approximately 200,000 Hungarians fled the country. Many Hungarian refugees came to New Jersey, some of whom were housed at Camp Kilmer, a military post near New Brunswick. Many members of the nearby Rutgers University community worked to help the refugees. In this document, the National Academy of Sciences announces its establishment of an office at the refugee center at Camp Kilmer. The point of the office is to interview Hungarian scientists and engineers in order to evaluate their areas and levels of expertise. Based on the evaluations, the Hungarians will be assisted with employment and research opportunities
Temperature effects on decomposition of Posidonia oceanica mat.
No full text14 páginas, 5 tablas, 4 figuras ,1 apéndice con 3 tablas.Posidonia oceanica mats act as an important carbon (C) sink in the Mediterranean by
accumulating roots, rhizomes and leaf sheaths, and allochthonous organic matter over millennia
due to low rates of decomposition of organic matter. Thus far, rates of decomposition have only
been modeled, whereas few attempts have been made to measure decomposition rates under in
situ conditions in P. oceanica mats. We studied decomposition of P. oceanica mats by simulating in
situ conditions at different temperatures. Samples from 5 different depths in a 3 m thick vertical
profile of a P. oceanica mat were each incubated under anoxic conditions for 7 mo at 5 different
temperatures (15, 20, 25, 30, and 35°C). Our measured low mat mineralization rates confirm slow
decomposition and support that P. oceanica mats act as important long-term C sinks in the
Mediterranean. However, between 15 and 25°C, both C and nitrogen (N) mineralization increased
with increasing temperature, and generally declined above 25°C, probably due to unbalanced
bacterial growth in the mat. Relatively, N mineralization was stimulated more than CO2 release
(i.e. up to 14.3 and 4.5 times, respectively), suggesting that regeneration of N in P. oceanica mats
is enhanced with increasing temperatures up to 25°C. This may affect the nutrient dynamics in
this oligotrophic ecosystem. Our data suggest that CO2 release due to decomposition of the mat is
potentially enhanced under a scenario of climate change, thus reducing the C sequestration
capacity of the mats during this century.M.Á.M. and O.S. together with the cruise were supported by
CSIC and the project SUMARII (CTM2006-12492), funded
by the Spanish Ministerio de Ciencia e Innovación. M.Ø.P.
and M.H. were supported by the Danish Natural Science
foundation (09-071369). M.Á.M. and O.S. belong to the
group ‘Ecología Bentónica’ SGR655.Peer reviewe
Microbial aspects of anaerobic methane oxidation with sulfate as electron acceptor
No full textAnaerobic oxidation of methane (AOM) is an important methane sink in the ocean but the microbes responsible for AOM are as yet resilient to cultivation. It was shown that AOM was coupled to sulfate reduction (SR) and this gave rise to current research which aims to develop a biotechnological process in which methane is used an electron donor for SR. This thesis describes the microbial analysis of an enrichment capable of high rate AOM (286 µmol.gdry weight-1.day-1) coupled to SR using a novel submerged membrane bioreactor system. Initially AOM rates were extremely low (0.004 mmol L-1 d-1), but AOM and SR increased exponential over the course of 884 days to 0.60 mmol L-1 d-1. The responsible organisms doubled every 3.8 months. By constructing a clone library with subsequent sequencing and fluorescent in situ hybridization (FISH), we showed that the responsible methanotrophs belong to the ANME-2a subgroup of anaerobic methanotrophic archaea, and that sulfate reduction is most likely performed by sulfate reducing bacteria commonly found in association with other ANME related archaea in marine sediments. Another relevant portion of the bacterial sequences can be clustered within the order of Flavobacteriales but their role remains to be elucidated. FISH analyses showed that the ANME-2a cells occur as single cells without close contact to the bacterial syntrophic partner. Incubation with 13C labeled methane showed substantial incorporation of 13C label in the bacterial C16 fatty acids (bacterial; 20, 44 and 49%) and in archaeal lipids, archaeol and hydroxyl-archaeol (21 and 20%, respectively). This confirms that both archaea and bacteria are responsible for the anaerobic methane oxidation in a bioreactor enrichment inoculated with Eckernförde bay sediment. To unravel the pathway of this syntrophic conversion, the effect of possible intermediates on AOM and SR was assessed. To investigate which kind of waste and process streams can be treated by the methanotrophic sulfate-reducing enrichment, the effect of environmental conditions and different substrates was assessed. The optimum pH, salinity and temperature for SR with methane by the enrichment were 7.5, 30‰ and 20°C, respectively. The biomass had a good affinity for sulfate (Km 75 KPa) and AOM was completely inhibited at 2.4 (±0.1) mM sulfide. The enrichment utilized sulfate, thiosulfate, sulfite and elemental sulfur as alternative electron acceptors for methane oxidation and formate, acetate and hydrogen as alternative electron donors for sulfate reduction. As a co-substrate for methane oxidation only methanol stimulated the conversion of 13C labeled CH4 to 13CO2 in batch incubations of Eckernförde bay sediment, other possible co-substrates had a negative effect on the AOM rate. The research described in this thesis shows the possibility of enriching slow growing methane oxidizing communities but also shows the difficulties in applying this process for a biotechnological purpose because of the extreme slow doubling times and the lack of understanding of the metabolic routes used by these organisms. <br/
Cohomogeneity One Manifolds And Hypersurfaces Of Revolution
No full text[No abstract available]11 BSUPPL. 2199215Alekseevsky, D.V., Riemannian manifolds of cohomogeneity one (1989) Col- Loq. Math. Soc. J. Bolyai, 56, pp. 9-22Alekseevsky, A.V., Alekseevsky, D.V., G-manifold with one dimensional orbit space (1992) Adv. Soc. Math., 8, pp. 1-31Besse, A., Einstein manifolds (1987) Ergeb. Math. Grenzgeb, 10 (3). , Springer- Verlag, BerlinBredon, G.E., (1972) Introduction to Compact Transformation Groups, , Acad. Press, New York, LondonDo Carmo, M., Dajczer, M., Rotation hypersurfaces in spaces of constant curvature (1983) Trans. A.M.S., 277, pp. 685-709Carmo, M.D., Dajczer, M., Mercuri, F., Compact conformally flat hypersurfaces (1985) Trans. A.M.S., 288, pp. 189-203Derdzinski, A., Mercuri, F., Noronha, M.H., Manifolds with nonnegative pure curvature operator (1987) Bol. Soc. Bras. Mat., 18, pp. 13-22Jensen, G.R., Homogeneous einstein spaces of dimension 4 (1969) J. Diff. Geom, 3, pp. 309-349Kobayashi, S., Compact homogeneous hypersurfaces (1958) Trans. A.M.S, 88, pp. 137-143Kobayashi, S., Nomizu, K., (1963) Foundations of Differential Geometry, , Wiley, New YorkKulkarni, R.S., Curvature structure and conformal transformations (1970) J. Diff. Geom, 4, pp. 425-451Noronha, M.H., Conformally flat immersions in codimension two (1987) Geometriae Dedicata, 23, pp. 115-130O'Neill, B., Stiel, E., Isometric immersions of constant curvature manifolds (1963) Mich. Math. J., 10, pp. 335-339Podestá, F., Spiro, A., Cohomogeneity one hypersurfaces of the Euclidean space (1995) Ann. Global Anal. Geom., 13, pp. 169-18
A design tool for timber gridshells: The development of a grid generation tool
No full textIn the last few years the timber gridshell has gained popularity. Recently two gridshells were constructed: the Weald and Downland gridshell in 2002 and the Savill Garden gridshell in 2006. These structures are examples from which the benefits of timber gridshells become apparent. A gridshell can display elegance and style, with its slender ribs curved into shape. It is also a sustainable structure, as the use of material is small, due to the shell behaviour. Also the timber can source from sustainable resources. Despite the advantages of the timber gridshell and the interest in sustainable engineering and free form architecture, the gridshell is not used very often. What can be seen as an important reason for this is the fact that the design process for a free form gridshell is rather complicated. An iterative design process is used to determine the grid geometry, which is only known to a few people. Main goal of this Master’s thesis is a study into the application of a design tool based on the geometrical properties of the grid of a grid shell, i.e. equal distance between the nodes on the quadrangle grid. The gridshell structure is a structure built with long slender laths. The laths are positioned in a flat quadrangle mat with one or more layers in two directions. This mat is then pushed and pulled into the desired shape by bending the laths and deforming the quadrangle meshes into rhombic shapes. When the desired shape is achieved, the laths are attached to edge supports and the structure is stiffened by diagonal bracing or applying a continuous layer on top of the laths. Timber is outstandingly suitable for this kind of building method. It is lightweight compared to its strength and can be bent and twisted relatively easy. Timber has always been used in structures by mankind. It was not until the twentieth century for timber to be used in large scale shell structures. In 1975 the first large scale timber gridshell was finished. This structure is the Multihalle in Mannheim. The structure can be seen as true pioneers work. The geometry of the structure was determined by physical form finding and it was constructed by pushing up the flat mat of laths by aid of scaffolding towers and fork lifts. More recently the Weald and Downland Gridshell and the Savill Garden gridshell were constructed. The former was constructed by lowering down the flat mat into shape on a special movable scaffolding. The latter was constructed by simply laying out the grid on a pre-shaped formwork. The gridshells were designed by aid of a computer form finding technique. The gridshell design tool has been set up to generate a gridshell grid on an arbitrary surface. The method used to generate the gridshell geometry uses two spheres to determine the intersection points of the gridshell laths. If the two spheres are positioned in such a way that their midpoints are located on the surface and that the two spheres are intersecting, there will be two intersection points between the two spheres and the surface. Together with the sphere midpoints, these four points form a mesh in the gridshell grid. A script has been created to execute this determination of points in a sequence which locates all possible intersection points on the surface. The sequence starts from start-off sections, interpolated on the surface. This implies that the correctness of the grid is dependent on the correctness of these start-off sections. Although the results of the grid generation tool look promising, further testing is advised to prove this. The design tool has been set up having the possibility to check the curve angles of the generated grid. From these angles the bending stresses can be calculated and checked if the bending or torsion stress criteria are exceeded. If this is the case, the checked element is given a colour. The generated structure can be checked visually for stress levels exceeding the stress criteria.Design and ConstructionCivil Engineering and Geoscience
Experimental study on premixed flame acceleration in closed pipe
No full textAn experimental study has been carried out to investigate the flame acceleration in closed pipe. A horizontal steel pipe, with 2 m long and 0.1 m diameter, giving L/D ratio of 20 was used in this project. For test with 90 degree bends, the bend has a radius of 0.1 m and added a further 1 m to the length of the pipe (based on the centerline length of the segment). Ignition was affected at one end of the vessel while the other end was closed. Natural gas/oxygen mixtures were studied with equivalence ratio, ? ranges from 0.5 to 1.8. It was demonstrated that bending pipe gave three times higher in overpressure (5.5 bars) compared to 2.0 bars of straight pipe. It is also shown that the flame speed is 63 m s-1, greater by factor of ~ 3 for explosion in bending pipe in comparison with straight pipe (23 m s-1). This is due to bending acting similar to obstacles. This mechanism could induce and create more turbulence, initiating the combustion of unburned pocket at the corner region, causing high mass burning rate and hence, increasing the flame speed
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