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Search Results: 1 - 10 of 202353 matches for " La?d "
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Crack initiation in steel parts working in boilers and steam pipelines
D. Renowicz,M. Cie?la
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: The purpose of this paper is to identify the influence of loading history and the processes of material degradation on the crack initiation and on durability under thermo-mechanical fatigue conditions.Design/methodology/approach: Based on the operation data, the conditions of laboratory examinations of specimens were determined. A specialist apparatus unit was used for the examination, enabling the simulation of any spectrum of mechanical load and temperature changes.Findings: The material durability criterion has been defined based on an energy related approach to the problem of crack initiation in steels which work under thermal fatigue conditions.Research limitations/implications: In the case discussed, i.e. a pipeline part, the present criteria should be expanded with critical values describing the total length of cracks initiated on the internal surface of a specimen.Practical implications: The paper refers to the research on steel 10H2M (10CrMo.910) used in the conventional boilers, superheaters and pipelines in power plants.Originality/value: Originality of the paper is the methodology of the lifetime prediction of steam pipeline parts working in thermo-mechanical fatigue conditions.
Formulation des besoins informationnels dans une activité complexe et dynamique: l’audit et le conseil en Système d’Information et Nouvelles Technologies
Boulesnane Sabrina,Bouzidi Lad
Communications of the IBIMA , 2009,
Abstract: De nos jours, l’exploitation des Technologies de l’Information et de la Communication (TIC) pour l’optimisation des Systèmes d’Information (SI) est plus que nécessaire. L’intégration de ces outils permet de renforcer les SI au sein des organisations et d’améliorer les processus fonctionnels. Afin de faciliter cette démarche, bon nombre d’organisations et notamment les Petites et Moyennes Entreprises (PME) s’appuient sur des cabinets d’audit et de conseil en SI et en TIC. Nous proposons dans cet article d’aborder les problèmes d’expression et d’interprétation des besoins rencontrés dans une cadre d’audit et de conseil en SI et en TIC. En effet, l’intégration massive des TIC au sein des PME s’accompagne par des difficultés en matière de précision et de qualité des informations contenues dans les cahiers de charges élaborés. Notre objectif consiste à analyser les particularités de ce cadre d’étude, tout en proposant un Système d’Aide à l’Interprétation des Besoins SAIB . Ce système est fondé sur plusieurs dimensions que nous considérons comme le socle du management moderne.
A note on the invariant distribution of a quasi-birth-and-death process
Manuel D. de la Iglesia
Mathematics , 2010, DOI: 10.1088/1751-8113/44/13/135201
Abstract: The aim of this paper is to give an explicit formula of the invariant distribution of a quasi-birth-and-death process in terms of the block entries of the transition probability matrix using a matrix-valued orthogonal polynomials approach. We will show that the invariant distribution can be computed using the squared norms of the corresponding matrix-valued orthogonal polynomials, no matter if they are or not diagonal matrices. We will give an example where the squared norms are not diagonal matrices, but nevertheless we can compute its invariant distribution.
Some examples of matrix-valued orthogonal functions having a differential and an integral operator as eigenfunctions
Manuel D. de la Iglesia
Mathematics , 2010,
Abstract: The aim of this paper is to show some examples of matrix-valued orthogonal functions on the real line which are simultaneously eigenfunctions of a second-order differential operator of Schr\"{o}dinger type and an integral operator of Fourier type. As a consequence we derive integral representations of these functions as well as other useful structural formulas. Some of these functions are plotted to show the relationship with the Hermite or wave functions.
Spectral methods for bivariate Markov processes with diffusion and discrete components and a variant of the Wright-Fisher model
Manuel D. de la Iglesia
Mathematics , 2011,
Abstract: The aim of this paper is to study differential and spectral properties of the infinitesimal operator of two dimensional Markov processes with diffusion and discrete components. The infinitesimal operator is now a second-order differential operator with matrix-valued coefficients, from which we can derive backward and forward equations, a spectral representation of the probability density, study recurrence of the process and the corresponding invariant distribution. All these results are applied to an example coming from group representation theory which can be viewed as a variant of the Wright-Fisher model involving only mutation effects.
Evaluation of an intensive insulin transition protocol in the intensive care unit setting: a before and after study
Jacobson LA,Jerguson K,Spiva LA,Fraser D
Pharmacy Practice (Granada) , 2012,
Abstract: The benefits of controlling blood glucose levels in intensive care units (ICUs) are well documented.Objective: This study determined the effectiveness and safety of a standardized transition order set for converting a continuous insulin infusion to a subcutaneous insulin regimen in non-cardiovascular surgery ICUs patient population.Methods: A retrospective study was conducted. Patients presenting with diabetic ketoacidosis or hyperosmolar hyperglycemic syndrome were excluded. One hundred patients were included prior to and 100 patients were included after initiating the transition order set. Blood glucose control was reviewed for up to 72 hours following the transition.Results: A total of 115 patients were included in data analysis: 85 prior to and 30 after transition protocol. All patients transitioned using the protocol were transitioned to basal insulin, compared to only 40% of the prior to protocol group. Patients transitioned correctly per the transition order set, “per protocol,” had 54% of blood sugars within the desired range, no increase in hypoglycemic events, and on average 5.56 hyperglycemic events (blood glucose >180 mg/dL) per person during the 72 hours compared to 6.68 and 9.00 for the prior to protocol group and the “off protocol” group (transitioned different than the protocol recommended), respectively (p= 0.05). There were significant differences in blood sugar control at 48 and 72 hours between the “per protocol” and “off protocol” groups (p= 0.01) and a 40% reduction in sliding scale or correctional insulin coverage.Conclusion: The addition of basal insulin to transition regimens resulted in fewer hyperglycemic events with no increase in hypoglycemic events. Patients transitioned “per protocol” had better glucose control demonstrated by: less hyperglycemic events, lower mean blood glucose levels at 48 and 72 hours, and lower need for correctional insulin. These findings showed benefits of glycemic control in the ICU by following a standardized transition protocol.
Use of Oat Bran in Bread: Fiber and Oil Enrichment and Technological Performance  [PDF]
Sofia Beccerica, María A. de la Torre, Hugo D. Sanchez, Carlos A. Osella
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.26079
Abstract: The effect of different amounts of oat bran on breadmaking was studied using also additives in the formulation. The aim of this experimental work was to evaluate the technological performance of oat bran in bread and the nutritional improvement resulting from the increased content of fiber and oil. Data were analyzed by ANOVA and the results were compared by Duncan’s test at a significance level of 0.05. With the addition of oat bran, the specific volume varied in such a way that the greater the amount of bran in the mixture, the lower the specific volume of bread. The addition of the proposed additives, however, helped significantly increase the volume. Besides, a change in the fatty acid profile, with a higher content in unsaturated fatty acids, as well as larger amounts of dietary fiber, was observed.
The Effects of Sample Matrices on Immunoassays to Detect Microcystin-LR in Water  [PDF]
Armah A. de la Cruz, Trevor J. Lynch, Dionysios D. Dionysiou
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.310145
Abstract: Immunoassays are widely used biochemical techniques to detect microcystins in environmental samples. The use of immunoassays for the detection of microcystins is vulnerable to matrix components and other interferents. This study is an evaluation of the effects of interfering substances commonly found in drinking and ambient water samples using commercially-available immunoassay kits for microcystin toxins. The microplate and strip test immunoassay formats were tested in the study. For the microplate ELISA, the following were found to inhibit microcystin-LR (MC-LR) detection: 250 μg/mL Ca2+ or Mg2+, 0.01% ascorbic acid, 0.1% EDTA chelating agent, 0.05 M glycine-HCl, pH 3. The following exhibited no effect: sodium chloride (NaCl, 1% to 4%) and sodium thiosulfate (0.001% and 0.01%), 0.01 to 0.1 M phosphate buffers (PB), pH 7 and 0.067 M PB at pH 5, 6, 7 and 8. Overall, up to 50 μg/mL of standard and reference natural organic matter (NOM) from various sources did not interfere in the assay system (without MC-LR) but diminished the detection of MC-LR at varying degrees. This is the first study evaluating standard and reference humic and fulvic acids from various sources in immunoassays for microcystins. The strip test also showed variable effects on MC-LR detection in the presence of NOM. This assay format was also sensitive to varying pHs and ionic strengths. MC-LR binding was inhibited at low pH (0.05 M glycine-HCl, pH 3), whereas, 0.067 M PB with pH 6, 7 and 8 can yield false positive results. Lower ionic strength of 0.01 M PB, pH 7 showed no interference in MC-LR binding whereas higher ionic strengths can interfere with MC-LR detection. NaCl at 3% and 4% can interfere with the analysis giving false positive results. Mg2+ at 50 and 250 μg/mL showed no effect on the analysis while the same concentration of Ca2+ can yield false positive results. The performance in marine, brackish and hard waters should be tested given the potential sensitivity to salinity. Results of this study may assist in the further refinement of existing assays and the development of practical antibody-based methods to clean-up samples and detect cyanotoxins in water.
Sirviendo a la Patria: Las maestras kindergarterinas en los albores del sistema de educación parvulario en Chile (1905-1915)
Abett de la Torre Díaz,Paloma;
Historia de la educaci?3n - anuario , 2011,
Abstract: this paper focuses on reconstructing the conformation of the nursery school system in chile between the years 1905 and 1915 and its consequences for feminine teachers. it will investigate from a gender perspective the type of formation of the nursery school teacher and the consequences for such subsequent development at this level. furthermore, it will explain what the intentions to generate a public kindergarten in santiago were, and if it is lacking compulsory education for primary school. for this essay, we consulted sources such as the educational magazine "el kindergarten nacional" as well as congressional proceedings.the first kindergarten will have two purposes: welfare and education. the aforementioned duality of the program marks the development of the system and will condition the teachers that work in this level. however, along with these changes, the nursery teachers are concerned to pass on the ideals of the modern state to reference a motherland and nation.
Determinación de la Efectividad de la Remediación de Suelos Accidentalmente Contaminados con ácido Sulfúrico mediante Métodos Geofísicos
Coria,Ignacio D; de la Vega,Matías;
Información tecnológica , 2011, DOI: 10.4067/S0718-07642011000100002
Abstract: this work demonstrates that the diagnosis of soils that have been contaminated with dangerous substances after remediation can be done with non invasive techniques, with cost and time reduction, and avoiding the sample cross contamination risks of invasive methods. the non-invasive methods used in this particular case of accidental contamination with concentrated sulphuric acid were electromagnetic induction and geoelectric. according to the results, it is concluded that the complementary use of both methods allows making a correct diagnosis of the remediation effectiveness.
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