177 research outputs found
Eastland pictured with O.B. Crocker
No full textInscribed: To a very/special friend,/O.B. Crockerhttps://egrove.olemiss.edu/joephoto_e/1348/thumbnail.jp
Cortisol response and immune-related effects of Atlantic salmon (Salmo salar Linnaeus) subjected to short- and long-term stress
No full textIt is generally considered that stress causes decreased immune function in fish. In this study we examined in Atlantic salmon (Salmo salar Linnaeus) the effects of both short- (a single 15 s out of water) and long-term (4 weeks of daily handling 15 s out of water) stress on plasma cortisol (free and total) and glucose levels, expression of interleukin-1\u3b2 (IL-1\u3b2) and survival of head kidney (HK) macrophages under culture with Aeromonas salmonicida. In the short-term study, samples were collected prior to the application of the stressor, and at 1, 3, 6, 12 and 24 h post stress. Free and total plasma cortisol levels and the percentage of free cortisol increased significantly in the stressed group at 1 and 3 h post stress. Plasma glucose levels were significantly higher than those of control fish at 1, 3 and 6 h post stress. Constitutive expression of IL-1\u3b2 in macrophages isolated from head kidneys in stressed fish was significantly higher at 1 and 3 h post stress. However, lipopolysaccharide (LPS) stimulated expression of IL-1\u3b2 in HK macrophages, exhibited significantly higher fold increases in unstressed fish compared to stressed fish. In the long-term study, with the exception of an increase in plasma glucose levels at 1 week, there were no significant differences in stress parameters between groups. There was a significantly higher constitutive IL-1\u3b2 expression in macrophages isolated from stressed fish over the first 2 weeks. At weeks 1, 2 and 3 the magnitude of IL-1\u3b2 response of isolated HK macrophages to LPS stimulation was reduced in >90% of the stressed fish. At 4 weeks there was no significant difference in inducible IL-1\u3b2 expression between the groups. Macrophages isolated from stressed fish also showed significantly decreased survival when exposed to A. salmonicida. This study shows a clear pattern from repeated handling stress, whereby effects on immune cells begin with increased constitutive expression of IL-1\u3b2, followed by decreased stimulation of leucocytes by extracellular antigen, and finally decreased leukocyte survival when exposed to A. salmonicida. The implications of these changes in the immune system will be discussed with respect to the use of classical indicators of stress to predict possible effects on the immune system of fish.Peer reviewed: YesNRC publication: Ye
Effects of Tafel slope, exchange current density and electrode potential on the corrosion of steel in concrete
No full textA Hierarchical Preconditioner For The Mortar Finite Element Method
No full textMortar elements form a family of nonconforming finite element methods that are more flexible than conforming finite elements and are known to be as accurate as their conforming counterparts. A fast iterative method is developed for linear, second order elliptic equations in the plane. Our algorithm is modeled on a hierarchical basis preconditioner previously analyzed and tested, for the conforming case, by Barry Smith and the second author. A complete analysis and results of numerical experiments are given for lower order mortar elements and geometrically conforming decompositions of the region into subregions. Copyright ©1996, Kent State University.47588Achdou, Y., Kuznetsov, Y.A., Substructuring preconditioners for finite element methods on nonmatching grids (1995) East-West J. Numer. Math., 3, pp. 1-28Achdou, Y., Kuznetsov, Y.A., Pironneau, O., Substructuring preconditioners for the Qi mortar element method (1995) Numer. Math., 71, pp. 419-449Achdou, Y., Maday, Y., Widlund, O.B., Methode iterative de sous-structuration pour les elements avec joints (1996) C.R. Acad. Sci. Paris, 322, pp. 185-190Achdou, Y., Maday, Y., Widlund, O.B., Iterative Substructuring preconditioners for the mortar finite element method in two dimensions (1996) Tech. Rep., Courant Institute of Mathematical Sciences, , In preparationBen Belgacem, F., Discretisations 3D Non Conformes pour la Methode de Decomposition de Domaine des Element avec Joints: Analyse Mathematique et Mise en vre pour le Probleme de Poisson (1993) Tech. Rep. HI-72/93017, , PhD thesis, Universite Pierre et Marie Curie, Paris, France, January Electricite de FranceBen Belgacem, F., Maday, Y., Adaption de la methode des elements avec joints au couplage spectral elments finis en dimension 3: Etude de l'erreur pour l'equation de Poisson, tech. rep., Electricite de France, April 1992 Tech. Rep. HI-72/7095.The mortar element method for three dimensional finite elements (1993) Unpublished Paper Based on Yvon Maday's Talk at the Seventh International Conference of Domain Decomposition Methods in Scientific and Engineering Computing, Held at Penn State University, , October 27-30Bernardi, C., Maday, Y., Mesh adaptivity in finite elements by the mortar method (1995) Tech. Rep. R94029, , Laboratoire d'Analyse Numerique, Universite Pierre et Marie Curie -Centre National de la Recherche Scientifique, JanuaryBernardi, C., Maday, Y., Patera, A.T., A new non conforming approach to domain decomposition: The mortar element method (1994) Collège De France Seminar, , H. Brezis and J.-L. Lions, eds., PitmanBjrstad, P.E., Wldlund, O.B., Iterative methods for the solution of elliptic problems on regions partitioned into substructures (1986) SIAM J. Numer. Anal., 23, pp. 1093-1120Bramble, J.H., A second order finite difference analogue of the first biharmonic boundary value problem (1966) Numer. Math., 9, pp. 236-249Casarin, M.A., Diagonal edge preconditioners in p-version and spectral element methods (1995) Tech. Rep., 704. , Department of Computer Science, Courant Institute, September SIAM J. Sci. ComputClarlet, P.G., (1978) The Finite Element Method for Elliptic Problems, , North-Holland, AmsterdamDryja, M., Additive Schwarz methods for elliptic mortar finite element problems (1996) Modeling and Optimization of Distributed Parameter Systems with Applications to Engineering, , K. Malanowski, Z. Nahorski, and M. Peszynska, eds., IFIP, Chapman & Hall, London, To appearDryja, M., Wldlund, O.B., Schwarz methods of Neumann-Neumann type for threedimensional elliptic finite element problems (1995) Comm. Pure Appl. Math., 48, p. 121155Tallec, P.L.E., Neumann-Neumann domain decomposition algorithms for solving 2D elliptic problems with nonmatching grids (1993) East-West J. Numer. Math., 1, pp. 129-146Maday, Y., Wldlund, O.B., Some iterative sub structuring methods for mortar finite elements: The lower order case (1996) Tech. Rep., Courant Institute of Mathematical Sciences, , In preparationSmith, B.F., Domain Decomposition Algorithms for the Partial Differential Equations of Linear Elasticity Tech. Rep., 517. , PhD thesis, Courant Institute of Mathematical Sciences, September 1990. Department of Computer Science, Courant InstituteSmith, B.F., Wldlund, O.B., A domain decomposition algorithm using a hierarchical basis (1990) SIAM J. Sci. Stat. Comput., 11, pp. 1212-1220Wldlund, O.B., Iterative sub structuring methods: Algorithms and theory for elliptic problems in the plane (1988) First International Symposium on Domain Decomposition Methods for Partial Differential Equations, , R. Glowinski, G. H. Golub, G. A. Meurant, and J. Periaux, eds., Philadelphia, PA, SIAMYserentant, H., On the multi-level splitting of finite element spaces (1986) Numer. Math., 49, pp. 379-41
Megafaunal distribution and biodiversity in a heterogeneous landscape: the iceberg scoured Rockall Bank, NE Atlantic
No full textSpecies distributions are influenced by spatial structure in environmental factors, but the scales at which these dependencies occur and the effect of habitat patch diversity, connectivity and spatial arrangement have rarely been investigated in deep-sea settings. In this study, spatially-limited photographic transects collected from Rockall Bank, Northeast Atlantic, were combined with sidescan and multibeam sonar maps to model spatial patterns in species distribution and biodiversity. Sediment interpretation maps were created and canonical ordination techniques were used to examine relationships between fine-scale sediment characteristics extracted from the digital stills as well as landscape metrics describing the patch mosaic structure of the surrounding areas. Fine-scale sediment characteristics explained 45.1% and 63.8% of the variation in species composition and biodiversity (H′) respectively. This survey effectively captured variation in species distribution resulting from iceberg ploughmarks, occurring at a scale of < 50 m which would normally go undetected by traditional ship-based studies. Our study suggests that fine-scale environmental information is required to capture the spatial heterogeneity of complex seafloor areas in sufficient detail to model species distributions and biodiversity
Parallelization of recurrent loops due to the preliminary computation of superpositions
No full textОлег БорисовичШтейнберг, кандидат физико-математических наук, старший научный сотрудник, лаборатория ≪Вычислительная механика≫, Институт математики,
механики и компьютерных наук им. И.И. Воровича, Южный федеральный университет (г. Ростов-на-Дону, Российская Федерация), [email protected]. O.B. Steinberg, South Federal University, Rostov-on-Don, Russian Federation,
[email protected]Как правило, именно циклы являются участками кода, вычисление которых занимает много времени. Поэтому, именно на них направляются особые усилия при ускорении программ, в частности, через распараллеливание.
В статье описывается алгоритм распараллеливания циклов, вычисляющих элементы рекуррентно заданной последовательности. Рекуррентные циклы, рассматриваемые в статье, непосредственно распараллелены быть не могут. С помощью вспомогательных преобразований иногда их можно привести к циклам, допускающим параллельное выполнение. Ранее автором статьи был опубликован другой алгоритм распараллеливания циклов, вычисляющих элементы рекурсивно заданной последовательности. В современных процессорах время выполнения арифметических операций оказывается на порядок меньше, чем считывание аргументов этих операций из оперативной
памяти. В данной статье приводятся оценки сложности по обращению к памяти, для
описываемого алгоритма. Представленный в статье параллельный алгоритм оказывается более эффективным по обращениям к памяти, чем алгоритм, описанный автором
ранее. As a rule, sections of code that take a lot of time to compute are loops. Therefore, it is
precisely on them that special efforts are directed when accelerating programs, in particular,
through parallelization.
The article describes the parallelization algorithm for loops calculating the elements
of a recursively given sequence. The recurrent loops considered in the article cannot be
directly parallelized. With the help of auxiliary transformations, they can sometimes be
reduced to loops that allow parallel execution. Earlier, the author of the article published
another algorithm for parallelizing loops that calculate the elements of a recursively given
sequence.
In modern processors, the execution time of arithmetic operations is an order of
magnitude faster than reading the arguments of these operations from RAM. This article
provides estimates of the complexity of accessing memory for the described algorithm. The
parallel algorithm presented in the article is more efficient in accessing memory than the
algorithm described by the author earlier.Работа поддержана грантом Правительства РФ № 075-15-2019-1928
Experimental uncertainty of measured entropy production with pulsed laser PIV and planar laser induced fluorescence
No full textThe article develops an uncertainty analysis for a newly measured variable of local entropy production. Entropy production is measured with post-processing and spatial differencing of measured velocities from particle image velocimetry (PIV), as well as temperatures obtained from planar laser induced fluorescence (PLIF). Measurement uncertainties of fluid velocity depend on the time interval between laser pulses, width of the camera view and other factors. Bias errors are related to elementary bias components and sensitivity coefficients in the uncertainty analysis. The precision errors use a confidence coefficient of 2 for a 95% confidence interval. The newly developed measurement technique and uncertainty analysis are successfully applied to pressure-driven channel flow and buoyancy-driven free convection in a square enclosure.Natural Sciences and Engineering Research Council of CanadaUniversity of Manitoba Graduate FellowshipCFI (Canada Foundation for Innovation)WED (Western Economic Diversification
Optimization correlation for entropy production and energy availability in film condensation
No full textThis article investigates the physical significance of entropy production in plate film condensation. An irreversibility distribution ratio yields similar trends as previous studies, whereby the Prandtl number has suggested the relevant influence of inertial effects. Results for the optimized entropy production and plate size are expressed in terms of a duty parameter. It is observed that entropy production provides a useful parameter in the optimization of a two-phase system
Spanningsverloop in dunne amorfe Mo/Si-multilagen tijdens een gloeibehandeling onder de glastemperatuur
No full textFysische en Chemische MetaalkundeTechnische MateriaalwetenschappenMechanical, Maritime and Materials Engineerin
Improvement and Adaption of Bearing Monitoring System
No full textWith the ongoing developments in the offshore wind turbine industry, weight reduction is an important aspect. With these weight reduction, manufacturers are trying to increase the effciency and size of their turbines. An example of such a technique is a single bearing drive train. These designs use a special bearing which is extra stiff due to the support of axial raceways. Manufacturers are still proving the robustness of this promising design. At the moment, some manufacturers already constructed a prototype. An example of this prototype is the XD115 of XEMC Darwind. This turbine is permanently monitored with the use of a health monitoring system. This system mainly consists of accelerometers which are located throughout the whole turbine. This monitoring system can be extended by performing spectral analysis on the measured generator current. The purpose of this thesis is to investigate if it is possible to measure mechanical vibrations in the current output of a generator with full converter. The bearing is one of the most complex elements in this single bearing drive train. There- fore, the focus is put on monitoring the bearing. In order to investigate in this topic, two types of tests are performed, lab tests and full scale tests. During the lab tests, a small set-up is made and some bearings are tested. The full scale tests are performed on the XD115 prototype. During the tests in the lab most of the characteristic bearing frequen- cies could be measured. An increase in the amplitude of these frequencies was measured after damaging the bearing. In these lab tests, an increase in friction was also measurable. The characteristic bearing frequencies could be identied much easier in the frequency spectrum of the current than in the frequency spectrum of the accelerometer. The re- sults of the tests in the full scale turbine were less promising. Neither in the frequency spectrum of the accelerometer and current, a characteristic bearing frequency could be identied. However, when the rotational speed synchronisation algorithm is used, some mechanical vibrations could be identied. The shaft speed and each time a blade passes the tower were identied in the frequency spectrum of the current. This means that a mechanical vibration was measured in the generator current.EPPElectrical Engineering, Mathematics and Computer Scienc
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