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Search Results: 1 - 10 of 9836 matches for " Laurent Bernard "
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A Sparse Flat Extension Theorem for Moment Matrices
Monique Laurent,Bernard Mourrain
Mathematics , 2008,
Abstract: In this note we prove a generalization of the flat extension theorem of Curto and Fialkow for truncated moment matrices. It applies to moment matrices indexed by an arbitrary set of monomials and its border, assuming that this set is connected to 1. When formulated in a basis-free setting, this gives an equivalent result for truncated Hankel operators.
Explicit factors of some iterated resultants and discriminants
Laurent Busé,Bernard Mourrain
Mathematics , 2006,
Abstract: In this paper, the result of applying iterative univariate resultant constructions to multivariate polynomials is analyzed. We consider the input polynomials as generic polynomials of a given degree and exhibit explicit decompositions into irreducible factors of several constructions involving two times iterated univariate resultants and discriminants over the integer universal ring of coefficients of the entry polynomials. Cases involving from two to four generic polynomials and resultants or discriminants in one of their variables are treated. The decompositions into irreducible factors we get are obtained by exploiting fundamental properties of the univariate resultants and discriminants and induction on the degree of the polynomials. As a consequence, each irreducible factor can be separately and explicitly computed in terms of a certain multivariate resultant. With this approach, we also obtain as direct corollaries some results conjectured by Collins and McCallum which correspond to the case of polynomials whose coefficients are themselves generic polynomials in other variables. Finally, a geometric interpretation of the algebraic factorization of the iterated discriminant of a single polynomial is detailled.
Les accrus de frêne dans les Pyrénées Centrales : un avenir énergétique local ?
Bernard Elyakime,Laurent Larrieu,Alain Cabanettes,Laurent Burnel
Revue de Géographie Alpine , 2012, DOI: 10.4000/rga.1534
Abstract: Alors que l’économie agricole de la montagne pyrénéenne centrale régresse, des peuplements forestiers naturels ont progressé sur des terres agricoles abandonnées, plus précisément sur d’anciennes prairies d’altitude. Nous définissons les conditions d’un usage énergétique de peuplements d’accrus de frênes installés sur ces terres. Un agriculteur propriétaire forestier d’accrus peut prendre en charge lui-même leur exploitation, y compris le transport jusqu’à sa ferme et la fente de ses bois, afin de satisfaire ses propres besoins de b ches de chauffage. Le propriétaire pourrait ainsi récupérer une valeur résiduelle unitaire maximale variant de 11,2 à 22,3 €/st (euros par stère), soit une valeur moyenne d’environ 16,8 €/st, tous co ts déduits. L’exploitation des accrus en bois b che pour le chauffage est donc financièrement possible. Une politique de développement d’une telle filière serait alors envisageable. Elle stimulerait les initiatives des agriculteurs propriétaires d’accrus forestiers. While the agricultural economy of Central Pyrenean is steadily declining, natural forest stands progress on agricultural mountainous meadows. For these forest extensions, we define the economic conditions of a new fuel-wood local economy. But it is possible that the forest owner makes himself logging, hauling and carriage to meet his heating needs, for a highest benefit from 11.2 to 22.3 €/st. So, an economy based on wood energy, with woods coming from private natural extension forests, is possible. It is based on an appropriate regional policy that will stimulate the necessary initiatives of forest owners of spontaneous ash reforestations to harvest these forest extensions.
Spontaneous ash tree reforestation in the Central Pyrenees: a future local energy source?
Bernard Elyakime,Laurent Larrieu,Alain Cabanettes,Laurent Burnel
Revue de Géographie Alpine , 2012, DOI: 10.4000/rga.1585
Abstract: With the agricultural economy of the Central Pyrenees in steady decline, natural forest stands are colonising abandoned agricultural meadows. The present study seeks to define the economic conditions for a new fuel-wood local economy based on these extensions of the forest cover. Farmer/forest owners are capable of exploiting this resource, involving logging, hauling and cutting the wood to size, to meet their own heating needs. In this way, owners could thus recuperate a maximum unit value estimated at 11.2 to 22.3 € per stere (1 cubic metre), or an average value of 16.8 € per stere after deduction of all costs. An economy based on wood energy, using wood from spontaneously generated forest growth on private land, is therefore possible. A development policy for such an activity could be envisaged with appropriate initiatives to stimulate the owners of land where spontaneous ash reforestation has occurred to harvest this potential resource.
Long Term Survival after Resection of a Small Bowel Metastasis of Lung Adenocarcinoma: A Case Report  [PDF]
Laurent Sulpice, Emanuele D’Errico, Alexis Arnaud, Michel Rayar, Karim Boudjema, Bernard Meunier
Journal of Cancer Therapy (JCT) , 2011, DOI: 10.4236/jct.2011.25092
Abstract: Background: Small bowel metastases of lung adenocarcinoma represent a rare clinical entity, often diagnosed after complications due to obstruction, bleeding or bowel perforation. Case Report: We report a case of ileal metastasis discovered during an intestinal perforation. The patient was a 47-year-old man hospitalized in emergency for acute abdominal pain, with right lower quadrant abdominal defense and a clinical history of left lower pulmonary lobectomy for lung adenocarcinoma 6 months before. Exploratory laparotomy for peritonitis revealed a single ileal tumor which was resected with lymph nodes excision. Pathology finding revealed that it was compatible with an ileal metastasis of his lung adenocarcinoma. Conclusions: The suspicion of a small bowel metastasis of lung carcinoma, although rare, must be taken in consideration and to carry out an extensive surgery, because only this will have an improvement on the survival of these patients. The purpose of this investigation is to add a new case report to the few that exist in order to provide a therapeutic approach to these exceptional cases.
How to Reduce Unnecessary Invasive Angiograms When Patients Are Initially Evaluated by Coronary Computed Tomography?  [PDF]
Edouard Cheneau, Brunot Vahda, Noémie Resseguier, Laurent Bernard, Annamaria Molon, Roch Giorgi, Dimitri Panagides
Advances in Computed Tomography (ACT) , 2013, DOI: 10.4236/act.2013.21003
Abstract: Purpose:When Coronary Computed Tomography (CCT) detects coronary obstruction, patients are regularly referred to invasive angiogram. With higher sensitivity than specificity, CCT might induce unnecessary angiograms (“false positive CCT”). We sought to determine the patients and CCT findings associated with false positive CCT. Methods: Patients were prospectively referred to CCT with a 64-slice CT scan for suspected CAD. Inclusion criteria were: 1) clinically suspected angina pectoris; or 2) suspected silent ischemia on resting EKG. Exclusion criteria were acute coronary syndrome and non sinus rhythm. Invasive coronary angiogram (ICA) was performed on the basis of CCT findings (stenosis >50%). Analysis was performed on a per patient basis. Results: Out of 702 patients, 228 had suspected significant stenosis by CCT and ICA was performed in 176 patients. Coronary stenosis >50% was not confirmed by ICA in 44 (25%). In multivariate analysis, we observed that atypical angina (OR 3.63,CI 1.43-9.66), silent ischemia (OR 5.11, CI 1.89-14.6) and number of suspected stenosed arteries by CCT (OR 1.81, CI 1.15-2.94) were independently predictive of false positive CCT (p < 0.05). Lesion location and coronary plaque characteristics did not impact on CCT accuracy. Conclusions:Performing CCT for atypical angina or silent ischemia is associated with higher rate of unnecessary invasive coronary angiograms. We failed to identify lesions characteristics prone to be “false positive” of CCT.
Thermal Activation of Asymetrical Composites for Vibration Control  [PDF]
Axel Imbert, Gildas L’Hostis, David Rigel Rigel, Fabrice Laurent, Bernard Durand
Modern Mechanical Engineering (MME) , 2013, DOI: 10.4236/mme.2013.33A001
Abstract:

The CBCM (Controlled Behaviour Composite Material) is a thermal active composite, which has been developed for morphing applications. The thermal activation is made by a source of heating generated within the composite structure. The coupling between the induced thermal field and the thermomechanical properties of the various components of the composite structure leads to the change of the structure shape. The heat source is generated by Joule effect, Carbon yarns inserted in the composite, are connected to a power supply. The application field of CBCM technology is the domain of shape modification and active assembly. The objective of this work is to illustrate the capabilities of CBCM in the domain of vibration control. We will study several reference plates with different constitution. The influences of these different constitutions, of the CBCM effect and the loss of stiffness for the matrix will be highlighted, for two boundary conditions, free/free and embedded/embedded.

Phosphorus Mass Balance of the Illinois River Watershed in Arkansas and Oklahoma  [PDF]
Bernard Engel, Meagan Smith, John Berton Fisher, Roger Olsen, Laurent Ahiablame
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.56060
Abstract:

Water quality degradation in the Illinois River Watershed (IRW) has been linked to excess nutrients, primarily phosphorus (P). A mass balance study was performed on the IRW in Oklahoma and Arkansas to quantify the magnitude of P entering the watershed between the closure of Lake Tenkiller’s dam in 1954 to 2006. Results showed that a substantial mass of P was, and is, being imported into the watershed relative to the mass of P leaving the watershed. The study demonstrated that poultry production has been the major contributor of P imported to the watershed since 1964, and is currently responsible for more than 76% of the net annual P additions to the IRW. Between 1949 and 2002, more than 200,000 tonnes of P was added to the IRW. A P delivery ratio for the IRW was computed from the mass balance results and observed loads indicating that 4% of annual P applied to the IRW landscape reached Lake Tenkiller between 1999 and 2006. Allocation of P loads from 1949 to 2002 to Lake Tenkiller computed with the delivery ratio showed that wastewater treatment plant (WWTP) discharges were responsible for more than 50% of P reaching Lake Tenkiller in 1949, followed by dairy cattle (32% of loads). Poultry contribution to P reaching Lake Tenkiller was 5% in 1949 but increased rapidly to become the largest source in 1969 at approximately 49%, and in 2002 at 54%. Both dairy and WWTP portions of the loads declined from 1949 levels with less than 4% attributable to dairy and less than 34% assigned to WWTP in 2002.

Modeling Water Quality Impacts of Growing Corn, Switchgrass, and Miscanthus on Marginal Soils  [PDF]
Mark A. Thomas, Laurent M. Ahiablame, Bernard A. Engel, Indrajeet Chaubey
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.614125
Abstract: The goal of the study was to model water quality impacts of growing perennial grasses on marginal soils. The GLEAMS-NAPRA and RUSLE models were used to simulate long-term surface runoff, percolation, erosion, total phosphorus (TP), and nitrate (NO3-N) losses associated with the production of corn-based bioenergy systems (i.e. conventional tillage corn and corn grain plus stover removal), switchgrass and Miscanthus on three marginal quality soils and one good quality soil in Indiana. Simulations showed that switchgrass and Miscanthus had no effect on annual runoff, but decreased percolation by at least 17%. Results also suggested a potential for reduction in erosion for Miscanthus across the soil types examined when compared to corn-based bioenergy production. The production of switchgrass and Miscanthus did not have significant effects on the simulated TP and NO3-N losses in runoff compared to corn production systems. Nitrates leached from fertilized Miscanthus production were approximately 90% lower than NO3-N leached from the production of fertilized switchgrass and corn systems. Additional studies are needed to better understand the hydrology, erosion and nutrient responses of Miscanthus and switchgrass production to meet bioenergy demands.
Improving Water Supply Systems for Domestic Uses in Urban Togo: The Case of a Suburb in Lomé
Laurent Ahiablame,Bernard Engel,Taisha Venort
Water , 2012, DOI: 10.3390/w4010123
Abstract: The rapid urbanization facing developing countries is increasing pressure on public institutions to provide adequate supplies of clean water to populations. In most developing countries, the general public is not involved in strategies and policies regarding enhancement, conservation, and management of water supply systems. To assist governments and decision makers in providing potable water to meet the increasing demand due to the rapid urbanization, this study sought to characterize existing water supply systems and obtain public opinion for identifying a community water supply system model for households in a residential neighborhood in Lomé, Togo. Existing water supply systems in the study area consist of bucket-drawn water wells, mini water tower systems, rainwater harvesting, and public piped water. Daily domestic water consumption in the study area compared well with findings on water uses per capita from Sub-Saharan Africa, but was well below daily water usage in developed nations. Based on the surveys, participants thought highly of a large scale community water tower and expressed interest in maintaining it. Even though people rely on water sources deemed convenient for drinking, they also reported limited confidence in the quality of these sources.
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