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Artykuły w czasopismach na temat "Conditions de charge variables"
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Wisawapipat, W., I. Kheoruenromne, A. Suddhiprakarn i R. J. Gilkes. "Surface charge characteristics of variable charge soils in Thailand". Soil Research 48, nr 4 (2010): 337. http://dx.doi.org/10.1071/sr09151.
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Surface charge characteristics were investigated using a charge fingerprinting procedure for 90 samples from 32 profiles of highly weathered Oxisols and Ultisols derived from shale/limestone, basalt, granite, local alluvium, sedimentary, and metasedimentary rocks under tropical savanna and tropical monsoonal climates in Thailand. The charge fingerprints of 5 whole soils, after removal of organic matter and of kaolin and ion oxides from these soils, were also measured to clarify factors contributing to the variable charge behaviour. Phosphate sorption was determined and related to charge properties. Kaolin was the dominant mineral of the clay fraction with moderate amounts of goethite and hematite. Gibbsite was present in Oxisols formed on limestone and basalt under more humid conditions. All soils exhibited variable charge behaviour but the magnitude and rate of change in variable charge with pH varied greatly between Oxisols and Ultisols. Oxisols had higher amounts of variable charge than Ultisols, reflecting the differences in amounts of clay and extractable Fe and Al. Oxisols formed on basalt and limestone under more humid conditions had high values of anion exchange capacity (AEC) due to the contributions of goethite, gibbsite, and boehmite. The relationships of base cation exchange capacity (CECB) and AEC with pH were linear. Rates of change with pH of both negative and positive variable charge (Ac, Aa) were closely related to CEC, specific surface area (SSA), pH(NaF), and various forms of extractable Fe, Al, and Mn. The charge fingerprints of soil after removal of organic matter indicated that organic matter exerted a strong influence on both the magnitude of negative charge and rate of change with pH. Kaolin had permanent and variable charge, with SSA and crystal size (MCD001) being highly predictive of the rate of change in variable negative charge with pH. Iron oxide concentrates exhibited strongly pH-dependent charge and the mean coherently diffracting length (MCD110) of hematite was highly predictive of both the magnitude and rate of change in variable positive charge with pH. Charge coefficients (Ac, Ba) had highly significant (P = 0.005) positive relationships with Langmuir and Freundlich phosphate sorption maximum coefficients (Xm, k), indicating that the surfaces of amorphous, poorly ordered, and crystalline Fe and Al oxides are prime sites for both P sorption and variable charge.
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Juban, Rusty, i Lara Gardner. "To File or Not to File? How EEOC Claims Change with the Economy". Labor Studies Journal 45, nr 3 (6.01.2020): 296–318. http://dx.doi.org/10.1177/0160449x19897403.
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Discrimination and sexual harassment are pervasive problems in today’s organizations. Traditionally, individual variables such as justice and power are used to study an employee’s response to discrimination or sexual harassment. In this study, we propose the use of economic variables (unemployment and economic health) to explain when an individual is more likely to make a discrimination or sexual harassment charge. Using monthly data from the U.S. Equal Employment Opportunity Commission on discrimination charges, we find there is strong evidence that U.S. economic conditions play an important role in the number and types of complaints filed.
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Shingne, Prasad S., Jeff Sterniak, Dennis N. Assanis, Claus Borgnakke i Jason B. Martz. "Thermodynamic model for homogeneous charge compression ignition combustion with recompression valve events and direct injection: Part II—Combustion model and evaluation against transient experiments". International Journal of Engine Research 18, nr 7 (26.08.2016): 677–700. http://dx.doi.org/10.1177/1468087416665052.
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This two-part article presents a combustion model for boosted and moderately stratified homogeneous charge compression ignition combustion for use in thermodynamic engine cycle simulations. The model consists of two parts: one an ignition model for the prediction of auto-ignition onset and the other an empirical combustion rate model. This article focuses on the development of the combustion model which is algebraic in form and is based on the key physical variables affecting the combustion process. The model is fit with experimental data collected from 290 discrete automotive homogeneous charge compression ignition operating conditions with moderate stratification resulting from both the direct injection and negative valve overlap valve events. Both the ignition model from part 1 and the combustion model from this article are implemented in GT-Power and validated against experimental homogeneous charge compression ignition data under steady-state and transient conditions. The ignition and combustion model are then exercised to identify the dominant variables affecting the homogeneous charge compression ignition and combustion processes. Sensitivity analysis reveals that ignition timing is primarily a function of the charge temperature, and that combustion duration is largely a function of ignition timing.
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Wohaib, Ameer Zuhair, i Nidhal Khazaal Maraie. "Variables affecting sulfasalazine - ion exchange resin complexation". Al Mustansiriyah Journal of Pharmaceutical Sciences 19, nr 4 (1.12.2019): 140–50. http://dx.doi.org/10.32947/ajps.v19i4.645.
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The aim of this work is studying the effect of different variables on the loading of sulfasalazine on DEAE sephadex A 25 ion exchange resin as a carrier for systemic action. Different drug: resin complexes (resinate) of different ratios (2:1, 1:1, 1:2, 1:4, 1:6) were prepared, dionized distilled
water used to prepare sulfasalazine solution, and their entrapment efficiency was estimated through changing variable conditions including temperature of stirring, stirring time, stirring speed, pH. The best complex was formed using 1:6 drug: resin ratio prepared at 50 ºC, stirring speed 400 rpm for 120 minutes in deionized water (pH 7). The prepared complex gave 77.8% drug release within 15 minute and continued up to 97.613% within 75 minute upon exchanging the drug with ions of similar charge in the dissolution medium (phosphate buffer pH 7.4).
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Edström, K., i S. T. Glad. "Algorithmic, physically based mode initialization when simulating hybrid systems". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 216, nr 1 (1.02.2002): 65–72. http://dx.doi.org/10.1243/0959651021541435.
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In the simulation of hybrid systems, discontinuities can appear at mode changes. An algorithm is presented that gives initial values for the continuous state variables in a new mode. The algorithm is based on a switched bond graph representation of the system, and it handles discontinuities introduced by a changed number of state variables at a mode change. The algorithm is obtained by integrating the bond graph relations over the mode change and assuming that the physical variables are bounded. This gives a relation between the variables before and after the mode change. It is proved here that the equations for the new initial conditions are solvable. The algorithm is related to a singular perturbation theory by replacing the discontinuity by a fast continuous change. The action is considered of a single switch and the corresponding continuous change, tuned by a single parameter. By letting this parameter tend to zero, the same initial state values are achieved as those derived by the presented algorithm. The algorithm is also related to physical principles such as charge conservation.
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Marchi, Giuliano, Cesar Crispim Vilar, George O’Connor i Marx Leandro Naves Silva. "Surface Complexation Modeling in Variable Charge Soils: Charge Characterization by Potentiometric Titration". Revista Brasileira de Ciência do Solo 39, nr 5 (październik 2015): 1387–94. http://dx.doi.org/10.1590/01000683rbcs20140528.
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ABSTRACT Intrinsic equilibrium constants of 17 representative Brazilian Oxisols were estimated from potentiometric titration measuring the adsorption of H+ and OH− on amphoteric surfaces in suspensions of varying ionic strength. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. The former was fitted by calculating total site concentration from curve fitting estimates and pH-extrapolation of the intrinsic equilibrium constants to the PZNPC (hand calculation), considering one and two reactive sites, and by the FITEQL software. The latter was fitted only by FITEQL, with one reactive site. Soil chemical and physical properties were correlated to the intrinsic equilibrium constants. Both surface complexation models satisfactorily fit our experimental data, but for results at low ionic strength, optimization did not converge in FITEQL. Data were incorporated in Visual MINTEQ and they provide a modeling system that can predict protonation-dissociation reactions in the soil surface under changing environmental conditions.
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Liu, Wei, Zhirun Yuan, Changbin Mao, Qingxi Hou i Kecheng Li. "Removal of hemicelluloses by NaOH pre-extraction from aspen chips prior to mechanical pulping". BioResources 6, nr 3 (28.07.2011): 3469–80. http://dx.doi.org/10.15376/biores.6.3.3469-3480.
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chips prior to mechanical pulping, which would offer new feedstocks for the production of chemicals and fuels. The aim of this study was to evaluate pre-extraction to maximize pre-extraction yield, while minimizing negative impacts on wood chips. The effects of three independent process variables (NaOH charge, pre-extraction temperature, and time) on three dependent variables (pre-extraction yield, xylan extraction yield, and cellulose content based on original wood) were studied using a Box-Behnken experimental design. The mathematical models were obtained and validated well. It was found that NaOH charge, time, interaction between NaOH charge and time, and interaction between temperature and time have significant effects on xylan extraction yield. The xylan extraction yield was 22.55%; i.e., about 37.3 kg of xylan could be extracted from one ton of oven-dried aspen chips under the conditions of 5.68% NaOH charge, 100 °C, and 35 min.
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Robertson, Kevin, Raynald Gauvin i James Finch. "Charge Contrast Imaging of Gibbsite Using the Variable Pressure SEM". Microscopy and Microanalysis 10, nr 6 (grudzień 2004): 721–32. http://dx.doi.org/10.1017/s1431927604040590.
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The variable pressure scanning electron microscope (VP-SEM) allows imaging of insulators without the need for a conductive coating, due to charge neutralization at the surface from recombination of positive ions and surface electrons. Varying certain parameters such as pressure, bias, and working distance creates incomplete neutralization, and localized charging develops called charge contrast. Although the exact mechanism creating charge contrast imaging (CCI) is unknown, it is agreed that it is related to an optimum charge compensation. The behavior of the CCI is still vague, which presents a problem for determining the mechanisms. This article provides user-friendly methods of finding the optimum levels of charge contrast in the VP-SEM. We show that the CCI is obtained at optimum operating conditions where the specimen current is between 2.5 nA and 3.5 nA. The specimen current is a function of secondary electrons (SE) emission and ionization potential, producing an ion flux. Therefore an optimum specimen current represents the balanced conditions of SE emission and ion flux. Controlling the pressure, working distance, bias, scan rate, and beam current allows the microscopist to set the specimen current at this optimum level for charge contrast imaging. All the work was performed on gibbsite using the S3000N VP-SEM from Hitachi.
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Suárez-Carreño, Franyelit, i Luis Rosales-Romero. "Anisotropy Induced by Electric Charge: A Computational Analytical Approach". Physics 6, nr 2 (16.05.2024): 780–92. http://dx.doi.org/10.3390/physics6020048.
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This paper presents a novel class of interior solutions for anisotropic stars under the imposition of a self-similar symmetry. This means proposing exact solutions to the Einstein field equations to describe charged matter distribution with radiation flow. The Einstein–Maxwell system by employing specific choices of mass function is formulated to describe the gravitational collapse of charged, anisotropic, spherically symmetric distributions using the Schwarzschild metric. Two ordinary differential equations governing the dynamics are derived by matching a straightforward solution of the symmetry equations to the charged exterior (Reissner–Nordström–Vaidya). Models with satisfactory physical behavior are constructed by extensively exploring self-similar solutions for a set of parameters and initial conditions. Finally, the paper presents the evolution of physical variables and the collapsing radius, demonstrating the inevitable collapse of the matter distribution.
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Osmolovskii, Nikolai P., Meizhi Qian i Jan Sokołowski. "Network optimality conditions". Control and Cybernetics 52, nr 2 (1.06.2023): 129–80. http://dx.doi.org/10.2478/candc-2023-0035.
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Abstract Optimality conditions for optimal control problems arising in network modeling are discussed. We confine ourselves to the steady state network models. Therefore, we consider only control systems described by ordinary differential equations. First, we derive optimality conditions for the nonlinear problem for a single beam. These conditions are formulated in terms of the local Pontryagin maximum principle and the matrix Riccati equation. Then, the optimality conditions for the control problem for networks posed on an arbitrary planar graph are discussed. This problem has a set of independent variables x i varying within their intervals [0, l i], associated with the corresponding beams at network edges. The lengths l i of intervals are not specified and must be determined. So, the optimization problem is non-standard, it is a combination of control and design of networks. However, using a linear change of the independent variables, it can be reduced to a standard one, and we show this. Two simple numerical examples for the single-beam problem are considered.
Rozprawy doktorskie na temat "Conditions de charge variables"
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Royer-Gaspard, Paul. "De la robustesse des modèles hydrologiques face à des conditions climatiques variables". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS466.
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L'un des défis pour les modèles hydrologiques utilisés pour simuler les effets du changement climatique sur les cours d’eau est d'être suffisamment robuste pour être performant dans des conditions climatiques variées. Cependant, les modèles actuels manquent généralement de robustesse. Les causes sont encore incertaines et potentiellement multiples (calage, données, structures). Cette thèse présente une recherche de solutions pour améliorer la robustesse des modèles hydrologiques, à travers plusieurs diagnostics menés sur un grand échantillon de bassins versants. Après une étape d’identification des changements climatiques les plus défavorables aux modèles, une comparaison de différentes méthodes de calage a abouti au constat que le choix de la fonction objectif avait une influence faible mais non négligeable sur la robustesse des modèles. Un choix adapté de la formulation de l'évaporation potentielle est également un facteur d'amélioration, bien que les résultats soient assez hétérogènes sur l'échantillon d'étude. Une méthodologie de diagnostic des lacunes structurelles des modèles hydrologiques, fondée sur une analyse des compétitions entre les performances, a ensuite été proposée et appliquée au modèle GR4J. Deux défauts majeurs ont ainsi pu être identifiés dans la structure du modèle, limitant sa capacité à se montrer robuste pour la simulation simultanée de plusieurs gammes d'écoulement. Une tentative de modification via l'ajout d'un paramètre au modèle s'est révélée encourageante. Malgré la modestie des progrès auxquels ils ont abouti, nous espérons que ces travaux pourront susciter de futurs développements de la structure des modèles hydrologiquesAmong the many challenges that climate change poses, the ability of hydrological models to adequately perform over a large range of climatic conditions is key its impacts on the regime of rivers. However, modern hydrological models still lack of robustness. The causes are yet uncertain and may be manifold: (calibration, measurement errors, model structure). This thesis aims at identifying solutions for model improvement by a series of diagnoses conducted on a large catchment set. After a study of the types of climatic changes challenging model robustness the most, we set up a comparison of different calibration methods. It revealed that the choice of the optimized objective function had a significant impact on model robustness. The way potential evaporation is computed also influences model robustness, although our comparison of a few potential evaporation models show rather heterogeneous results across the catchment set. A method specifically designed to diagnose structural weaknesses impacting model robustness, based on an analysis of performance trade-offs in a multi-objective framework, was then proposed and applied to the GR4J model. A couple of major structural deficiencies was identified. These deficiencies likely prevent the model from providing robust simulations in different streamflow ranges simultaneously. An attempt to modify the structure of GR4J yielded to an encouraging yet modest improvement of its performance. Despite the light enhancement of hydrological model robustness achieved in this work, it may pave the way to further advances toward model structural development
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Wang, Chu. "Deep learning-based prognostics for fuel cells under variable load operating conditions". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0530.
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Les systèmes de piles à combustible à membrane d'échange de protons (PEMFC) conviennent à diverses applications dans le domaine des transports, mais leur coût élevé et leur manque de durabilité restent les principaux facteurs limitant leur commercialisation à grande échelle. Dans les applications de transport, la détérioration des PEMFC est aggravée par des conditions de charge variables, ce qui entraîne une diminution de leur durée de vie utile restante (RUL). La gestion des pronostics et de la santé (PHM) est un outil efficace pour prévoir les risques du système, gérer les calendriers de contrôle/maintenance du système, améliorer la sécurité et la fiabilité du système, prolonger la durée de vie du système et réduire les coûts d'exploitation/maintenance. Le pronostic est une base importante et un support clé pour le PHM, et ses tâches principales incluent l'extraction d'indicateurs de santé, la prédiction des tendances de dégradation et l'estimation de la RUL. Les caractéristiques de dégradation à long terme des PEMFC sont dissimulées dans des conditions de charge variables, ce qui augmente la difficulté d'extraction des indicateurs de santé, réduit la précision de la prédiction de la dégradation et inhibe la fiabilité de l'estimation de la durée de vie. Dans cette optique, le travail de thèse part de la modélisation du comportement de dégradation des PEMFC dans des conditions de charge variables et mène des travaux de recherche sur l'extraction d'indicateurs de santé, la prédiction des tendances de dégradation à court/long terme, l'estimation RUL et l'évaluation de la fiabilitéProton exchange membrane fuel cell (PEMFC) systems are suitable for various transportation applications thanks to their compact structure, high power density, low start/running temperature, and zero carbon emissions. High cost and lack of durability of PEMFC are still the core factors limiting their large-scale commercialization. In transportation applications, the deterioration of PEMFCs is aggravated by variable load conditions, resulting in a decrease in their Remaining Useful Life (RUL). Prognostics and health management (PHM) is an effective tool to forecast potential system risks, manage system control/maintenance schedules, improve system safety and reliability, extend system life, and reduce operation/maintenance costs. Prognostics is an important foundation and key support for PHM, and its core tasks include health indicator extraction, degradation trend prediction, and RUL estimation. The long-term degradation characteristics of PEMFC are concealed in variable load conditions, which increases the difficulty of health indicator extraction, reduces the accuracy of degradation prediction, and inhibits the reliability of life estimation. In view of this, the thesis work starts from modeling the degradation behavior of PEMFC under variable load conditions and carries out research work on health indicator extraction, short/long-term degradation trend prediction, RUL estimation and reliability evaluation
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Mernik, Luka. "Positivity Conditions in Several Complex Variables". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586522855649564.
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Daussin, Frédéric Piquard François. "Effets d'un entraînement en endurance à charge constante, à charge variable ou à haute intensité chez l'homme étude intégrative du systémique au cellulaire /". Strasbourg : Université Louis Pasteur, 2008. http://eprints-scd-ulp.u-strasbg.fr:8080/1000/01/DAUSSIN__Frédéric_2007.pdf.
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Daussin, Frédéric. "Effets d'un entraînement en endurance à charge constante, à charge variable ou à haute intensité chez l'homme : Etude intégrative du systémique au cellulaire". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/DAUSSIN_Frederic_2007.pdf.
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L’entraînement en endurance fait partie des programmes de réhabilitation des patients atteints de maladies chroniques, il améliore les performances aérobies et participe à l’amélioration de la qualité de vie des ces patients. Deux modalités sont principalement utilisées : l’entraînement en intervalles, associé à des variations d’intensité au cours de la séance, et l’entraînement à charge constante dont l’intensité reste identique pendant toute la durée de la séance. Ce travail de thèse se propose dans une première partie de comparer les effets de ces deux modalités d’entraînement à travers une étude intégrée, allant des paramètres systémiques aux paramètres musculaires. Pour cela, seize sujets ont effectué les deux modalités d’entraînement ayant comme caractéristiques principales : une durée d’entraînement et une dépense énergétique identiques. Les deux modalités permettent l’amélioration des performances aérobies à travers des adaptations différentes. L’entraînement en intervalles induit des adaptations centrales (débit cardiaque) et périphériques (densité capillaire et capacités oxydatives musculaires) tandis que l’entraînement à charge constante augmente de manière plus importante la densité capillaire. L’effet de l’entraînement en endurance à haute intensité, sur la fonction mitochondriale, est étudié à travers la comparaison de populations de sédentaires et de sportifs de haut niveau. Les sportifs en endurance présentent des modifications à la fois quantitatives et qualitatives de la fonction mitochondriale, en particulier en majorant leur capacité à oxyder les hydrates de carbone. Ces résultats contribuent à la compréhension des mécanismes adaptatifs en réponse à l’entraînement en endurance. Ils favoriseront d’une part l’amélioration de la prescription de l’entraînement en endurance, en ciblant la modalité d’entraînement en fonction des pathologies, et d’autre part l’amélioration de la qualité de vie des patients atteints de maladies chroniquesEndurance training is currently used in chronical diseases to improved aerobic performance and quality of life of these patients. Continuous endurance training and interval training are the both modalities used in rehabilitation. In a first part, we compared the effects of these two trainings modalities from systemic to cellular adaptations. Sixteen subjects performed the both trainings modalities which are characterized by same energy expenditure and training duration. Aerobic performance was improved by both trainings modalities throughout different adaptations. Interval training improved central adaptations (cardiac output) and peripheral adaptations (capillary density and mitochondrial function) whereas continuous training enhanced capillary density. In the second part, we compared sedentary subjects and endurance athletes to determine the effect of endurance training at high intensity on mitochondrial function. Athletes presented quantitative and qualitative modifications toward a greater capacity to oxidize carbohydrate. Our results improve the knowledge about the endurance training induced adaptation. They favorite the endurance training prescriptions for chronical disease patients and allow to choose the training modality in function of patient’s disease. Finally, it will improve quality of life of chronical disease patients
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ALI, MOHAMED ABDEREMANE. "Validite des cinetiques de sechage sous des conditions d'air variables". Poitiers, 1992. http://www.theses.fr/1992POIT2311.
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Le but de ce travail est de definir les limites de validite des cinetiques de sechage lorsque les caracteristiques locales de l'air dans un sechoir, varient fortement d'un endroit a un autre. L'etude est menee aussi bien numeriquement qu'experimentalement sur un materiau poreux non hygroscopique: la brique. Apres une revue bibliographique des principaux modeles de transfert de chaleur et de masse, c'est un modele de prise de moyenne qui est retenu: celui de whitaker. Ce dernier est resolu en monodimensionnel par la methode numerique des volumes de controle (methode de patankar). Le paradoxe de whitaker est revu et discute, et une etude de sensibilite de certains parametres est effectuee. Cette etude montre que, l'amelioration du modele passe par la connaissance precise de la permeabilite relative au liquide specialement aux faibles saturations, de la saturation irreductible en fonction de la distribution des pores et des coefficients d'echange en fonction de la saturation en surface. L'outil numerique ci-dessus etant mis en place, l'examen des cinetiques globales de sechage avec des conditions d'air variables est alors aborde, l'etude experimentale etant completee par la simulation numerique des variations des caracteristiques de l'air sous differentes formes. En vue de la gestion d'un sechoir, la simulation a ete reprise en utilisant un modele theorique simple de diffusion ou le coefficient global de migration de l'humidite est obtenu a partir des cinetiques experimentales. Les resultats montrent que, si la variation d'une des caracteristiques de l'air est relativement rapide, la cinetique perd momentanement son sens
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Nguyen, Thi Minh Phuong. "Lead acid batteries in extreme conditions : accelerated charge, maintaining the charge with imposed low current, polarity inversions : Introducing non-conventional charge methods". Montpellier 2, 2009. http://www.theses.fr/2009MON20063.
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Les trois grands domaines d'application de batteries au plomb sont les batteries de démarrage, les batteries de traction et les batteries stationnaires. Les évolutions des marchés, notamment celui de l'énergie, ouvrent de nouvelles applications de stockage par accumulateur au plomb: transports électriques, énergies renouvelables dont éolien et photovoltaïque, stockage réseau, qualité, secours. Dans la plupart des cas, les contraintes de l'application mènent à revoir profondément les algorithmes de charge. Nous avons mené différentes études sur les batteries au plomb dans des conditions extrêmes: charge rapide pour batteries ouvertes, maintien en charge pour batteries stationnaires, décharge profonde avec inversion de polarité. À partir de ces travaux, un nouvel algorithme de charge rapide avec une phase de déstratification précoce a été mis au point. De plus, une nouvelle méthode de maintien en charge par faible courant imposé a été testée sur différentes technologies de batteries au plomb. Elle montre plusieurs avantages en termes de réduction importante de la corrosion, de diminution de la perte d'eau due à la corrosion et de besoin de charges périodiquesThree main applications of lead acid batteries are: starting, lighting and ignition batteries (SLI batteries), motive batteries and stationary batteries. Increasing attention to the global climate change and the sustainable development open new applications for the energy storage using lead acid batteries: electric transport, renewable energies such as photovoltaic and wind, grid storage, quality and emergency supplies. In some cases, new applications need new charge algorithms. Various studies were conducted with lead acid batteries in extreme conditions: accelerated charge for vented batteries, maintaining the charge with imposed low current for stationary batteries and deep discharge with polarity inversion. A new charge method for accelerated and fast charges of flooded lead acid batteries is developed. A new method of maintaining the charge with imposed low currents and periodical charges is tested on different technologies of lead acid batteries. It has the advantages of reducing drastically corrosion, of limiting water loss due to corrosion and the need of periodical charges
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Johnson, Stephen E. "Response of mat conditions and flakeboard properties to steam- injection variables". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03242009-040404/.
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Carlsson, Sandra J. E. "Experimental studies of spin, charge and orbital order at extreme conditions". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3169.
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Spin, charge and orbital ordering in various crystalline compounds have been studied under extreme conditions. The main techniques used were synchrotron X-ray and neutron powder diffraction. High-pressure conditions were obtained by using a diamond anvil cell and the Paris-Edinburgh cell. Changes in the valence state of BiNiO3 perovskite under pressure have been investigated by a neutron powder diffraction study and bond valence sum (BVS) calculations. At ambient pressure, BiNiO3 has the unusual charge distribution Bi3+0.5Bi5+0.5Ni2+O3 with ordering of Bi3+ and Bi5+ charges on the A sites of a highly distorted perovskite structure. High pressure neutron diffraction measurements show that the pressure-induced melting of the charge disproportionated state leads to a simultaneous charge transfer from Ni to Bi, so that the high pressure phase is metallic Bi3+Ni3+O3. This exceptional charge transfer between A and B site cations coupled to electronic instabilities at both sites gives rise to a remarkable variety of ground states. Furthermore, Rietveld analysis of low temperature neutron powder diffraction data shows that the structure of BiNiO3 remains triclinic (space grp 1P) throughout the temperature range 5 to 300 K. BVS calculations confirm that the charge distribution is Bi3+0.5Bi5+0.5Ni2+O3 down to 5 K. The magnetic cell is identical to that of the triclinic superstructure and a G-type antiferromagnetic model gives a good fit to the magnetic intensities, with an ordered Ni2+ moment of 1.76(3) μB at 5 K. However, BiNiO3 is ferrimagnetic due to the inexact cancellation of opposing, inequivalent moments in the low symmetry cell. The effect of high pressure on the structural properties of (EDT-TTF-CONH2)6[Re6Se8(CN)6], a conducting, molecular, mixed-valence, π-conjugated radical, cation salt has been examined using synchrotron X-ray diffraction and a diamond anvil cell set-up. It has previously been shown that this compound undergoes a low temperature phase transition from a rhombohedral (space group 3R) to a triclinic (space group1P) structure at ~150 K. This transition is caused by a charge ordering. A LeBail profile fitting of powder diffraction data revealed a change in compressibility at 0.7 GPa indicative of a phase transition. This was confirmed by single crystal data which showed that the structure remains rhombohedral )3(R, up i to 0.4 GPa but is triclinic )1(P at 0.8, 1.2 and 1.8 GPa. Hence, high pressure, as well as low temperature, can drive the charge ordering in (EDT-TTF-CONH2)6 [Re6Se8(CN)6]. The transition pressure is between 0.5-0.7 GPa at 300 K. The crystal and magnetic structures of the orbitally ordered perovskite KCrF3 have been determined from neutron powder diffraction measurement at temperatures from 3.5 to 300 K. A phase transition from a tetragonal to a monoclinic structure occurs at 250 K but the orbital ordering is sustained. Long range antiferromagnetic order of the A-type occurs below TN = 46 K and the refined magnetic moment for the Cr2+ sites was found to be 4.39(7) μB.
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Pimouguet, Clement. "Prise en charge des démences : pertinence et conditions d’efficacité du Case Management et de la prise en charge usuelle". Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21894/document.
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Les démences représentent un enjeu majeur de santé publique. Les carences organisationnelles de notre système de santé ne garantissent pas la qualité et la cohérence du parcours de soins des malades et de leurs familles. Le plan national Alzheimer 2008-2012 a introduit de nouveaux dispositifs ayant pour objectifs de mieux prendre en compte les besoins des malades et des familles et de mettre en place des offres adaptées. L’objectif général de cette thèse était d’étudier la prise en charge des démences en s'intéressant à la fois à une prise en charge pouvant être qualifiée d'optimale (le case management) et à la prise en charge effective en pratique courante. Dans une première partie, nous avons donc étudié l’efficacité du case management dans la démence et caractérisé les conditions d’optimisation de ce modèle de soins collaboratifs. Tout d’abord, nous nous sommes intéressés aux conditions d’efficacité dans un domaine où le niveau de preuve était élevé (le diabète) puis nous avons cherché à caractériser les points saillants pouvant conditionner l’efficacité du case management dans la démence. Quelques essais contrôlés randomisés de case management rapportent des résultats encourageants dans la démence sur des critères cliniques (troubles du comportement du malade, qualité de vie ou fardeau de l’aidant) ou sur l’institutionnalisation. L’efficacité est démontrée principalement auprès de patients inclus à des stades plutôt modérés. L’efficacité d’une intervention préventive dès le diagnostic est inconnue et mérite d’être testée. C’est pourquoi l’essai AIDALZ a été envisagé et est actuellement mené auprès de déments nouvellement diagnostiqués. Dans une deuxième partie, nous avons étudié la prise en charge telle qu'elle est actuellement réalisée en France. Nous avons d'abord décrit cette prise en charge et analysé les déterminants d’un recours aux soins dès le début de la maladie. Puis nous avons évalué les bénéfices de ce recours aux soins sur la survie des déments. Les différentes analyses de survie menées n’ont pas démontré de bénéfice d’un recours aux soins dès le début de la maladie chez des déments incidents des cohortes populationnelles des 3 Cités et de PAQUID. Ce travail témoigne de la difficulté de prendre en compte tous les facteurs pouvant influer sur l’accès aux soins et/ou sur la survie dans des études observationnelles. De nouvelles recherches doivent être menées pour étudier les bénéfices d’un diagnostic dès le début de la maladie sur des indicateurs variés du pronostic. Des essais d’intervention seraient nécessaires pour évaluer plus précisément l’intérêt du diagnostic et de la prise en charge dans la démenceDementia represents a major public health issue. The organisational carencies of our health system do not guarantee the quality of the care channels for patients and families. The national Alzheimer plan 2008-2012 has introduced new health facilities whose objectives are to better take into account patients and families needs and to implement tailored care. The main aim of this thesis was to evaluate care of demented patients, both optimal care (the case management) and usual care. In the first part we studied case management effectiveness and delineated conditions to optimize the effectiveness of this collaborative model of care. Firstly, we concentrated our attention on effectiveness conditions in diabetes and we studied case management in dementia. Some randomized controlled trials of case management reported promising impacts on clinical criteria (patient’s behavioural troubles, caregiver burden or quality of life) or patient’s institutionalization. Case management effectiveness is reported mainly for patients at moderate stages. The effectiveness of a preventive intervention early in the disease process is unknown, but it deserves further investigation; that is why, the AIDALZ trial has been planned and is currently under way. In a second part, we studied the real care of demented patients in France. We firstly described the care and analysed the determinants of an early recourse to care for incident dementia patients. Then, we evaluated the benefits of recourse to care at the onset of dementia on survival. The different survival analyses performed did not report any benefit of an early recourse to care on incident dementia patients from the PAQUID or the 3 City population-based cohorts. These findings underlie the difficulties to take into account factors interfering with recourse to care and/or survival in observational studies. Further studies should be planned to investigate the benefits of early dementia diagnosis on various prognostic indicators. Intervention trials would be necessary to conclude on the relevance of early diagnosis in dementia
Książki na temat "Conditions de charge variables"
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Se prendre en charge ou disparaître. Port-au-Prince, Haïti: Bibliothèque Nationale, 2004.
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Asociación de Investigación y Estudios Sociales (Guatemala), red. Análisis coyuntural de las principales variables económicas. Guatemala: ASIES, 1997.
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Salvador, Soledad. Series de largo plazo de algunas variables económicas y sociales, Uruguay. Montevideo, Uruguay: CIEDUR, 1996.
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Kouassi, Eugène. Effects of inflation on Ivorian fiscal variables: An econometric investigation. Nairobi: African Economic Research Consortium, 1996.
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Taking charge of your life. Grand Rapids, Mich: F.H. Revell, 1999.
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A charge for the angels: A memoir. Stanville, Ky: Vantage Point, 2010.
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Zarnowitz, Victor. Major macroeconomic variables and leading indexes: Some estimates of their interrelations, 1886-1982. Cambridge, MA: National Bureau of Economic Research, 1989.
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F, Nalepa T., i Great Lakes Environmental Research Laboratory, red. Physical and chemical variables of Saginaw Bay, Lake Huron, in 1991-93. Ann Arbor, Mich: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Great Lakes Environmental Research Laboratory, 1996.
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P, Hoffmeyer-Zlotnik Jürgen H., i Wolf Christof, red. Advances in cross-national comparison: A European working book for demographic and socio-economic variables. New York: Kluwer Academic / Plenum Publishers, 2003.
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Joydeep, Dutta, red. Optimality conditions in convex optimization: A finite-dimensional view. Boca Raton: CRC Press, 2012.
Znajdź pełny tekst źródłaCzęści książek na temat "Conditions de charge variables"
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Germann, Thiemo, Daniel M. Martin, Christian Kubik i Peter Groche. "Mastering Uncertain Operating Conditions in the Development of Complex Machine Elements by Validation Under Dynamic Superimposed Operating Conditions". W Lecture Notes in Mechanical Engineering, 236–51. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_19.
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AbstractMachine elements produced in large quantities undergo several development cycles and can be adapted from generation to generation. Thus, experiences from real operation can be taken into account in further development. This is not possible for innovative investment goods such as special purpose machines, as these are usually individual items. Therefore, functionality and quality of newly developed components must be assured by previous investigations.Conventional methods are inadequate at this point, as they cannot represent the actual, complex operating conditions in the later application. A reliable statement about the behavior of the system through a comprehensive validation in laboratory tests under standardized conditions is not achievable in this way due to a multitude of diversified load cases.In previous work, a method was developed to allow testing of machine elements in the laboratory under detuned operating conditions. For this purpose, disturbance variables are applied to the system using paraffin wax phase change actuators in order to simulate real operation states and to analyze the behavior of the machine element under these conditions. The investigated disturbance variables are fluctuations and asymmetries of the operating load through superimposed temperature gradients. Complex interactions between the machine element and the adjacent components or the overall system can thus be taken into account.The functionality of the methodology has been developed and briefly demonstrated so far. This paper presents the next level within the development process of the methodology. The necessary components are explained in detail and an AI black box evaluation tool is discussed. This work is based on a test bench that applies dynamically changing states of detuning under superimposed disturbances. Additionally, energy efficiency and performance of the test setup is advanced. As presented, the method opens up the possibility of validating new machine elements in the laboratory under realistic conditions.
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Wagener, Thorsten. "On the Evaluation of Climate Change Impact Models for Adaptation Decisions". W Springer Climate, 33–40. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-86211-4_5.
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AbstractDetailed understanding of the potential local or regional implications of climate change is required to guide decision- and policy-makers when developing adaptation strategies and designing infrastructure solutions suitable for potential future conditions. Impact models that translate potential future climate conditions into variables of interest (such as drought or flood risk) are needed to create the required causal connection between climate and impact for scenario-based analyses. Recent studies suggest that the main strategy for the validation of such models (and hence the justification for their use) still heavily relies on the comparison with historical observations. In this short paper, the author suggests that such a comparison alone is insufficient and that global sensitivity analysis provides additional possibilities for model evaluation to ensure greater transparency and better robustness of model-based analyses. Global sensitivity analysis can be used to demonstrate that the parameters defining intervention options (such as land use choices) adequately control the model output (even under potential future conditions); it can be used to understand the robustness of model outputs to input uncertainties over different projection horizons, the relevance of model assumptions, and how modelled environmental processes change with climatic boundary conditions. Such additional model evaluation would strengthen the stakeholder confidence in model projections and therefore into the adaptation strategies derived with the help of these model outputs.
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Balogun, R. Ayodeji, E. Adesanya Adefisan, Z. Debo Adeyewa i E. Chilekwu Okogbue. "Thermodynamic Environment During the 2009 Burkina Faso and 2012 Nigeria Flood Disasters: Case Study". W African Handbook of Climate Change Adaptation, 1705–20. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_143.
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AbstractCritical or extreme atmospheric conditions which could result in flood disasters are important output for numerical weather forecast. This research applied thermodynamic variables to investigate the environment of two flood scenarios in West Africa as captured by the Tropical Rainfall Measurement Mission (TRMM) satellite. Results from the two case studies of flood events, in (i) Burkina Faso and (ii) Nigeria savannah, investigated in this research work, indicated that the September 1st 2009 flood, which was as a result of a single volumetric rainfall event of 408,070.60 ((mm/h)*km2) with 65% convective region in Burkina Faso, was initiated by interactions between extremely large lower tropospheric wind shear and cold pool dynamics. The case of the Nigeria savannah floods between July and September, 2012, was triggered by both continuous rainfall and release of water from the lagdo dam in Cameroon, which affected most of the communities in the river Benue axis. The continuous rainfalls were found to be as a result of extremely high convergence of moisture in the river Benue axis at different locations and periods. One of such rainfall events, as captured by TRMM satellite during September 29, 2012 in the Nigeria rainforest zone, indicated that the volumetric rainfall is 351,310.9 ((mm/h)*km2) with only 34% convective portion. From these results, it can be deduced that a combination of thermodynamic environmental variables, volume rainfall, and other satellite-derived convective parameters could provide important information for flood forecasting.
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Garrett, Steven L. "Ideal Gas Laws". W Understanding Acoustics, 333–56. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_7.
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Abstract This is the first chapter to explicitly address fluid media. For springs and solids, Hooke’s law, or its generalization using stress, strain, and elastic moduli provided an equation of state. In fluids, we have an equation of state that relates changes in pressure (stresses) to changes in density (strain). The simplest fluidic equations of state are the Ideal Gas Laws. Our presentation of these laws will combine microscopic models that treat gas atoms as hard spheres with phenomenological (thermodynamic) models that combine the variables that describe the gas with conservation laws that restrict those variables. The combination of microscopic and phenomenological models will give us the important characteristics of gas behavior under isothermal or adiabatic conditions and will provide relationships between gas heat capacities and their constituent particles when augmented with elementary concepts from quantum mechanics. The chapter ends by adding a velocity field to the pressure, temperature, and density, thus providing the equations of hydrodynamics that will guide all of the subsequent development of acoustics in fluids.
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Adeleke, Lydia, Jacob Victor Jerry, Desalegn Ayal, Akinola Joshua Oluwatobi, Ayodele Idowu Sunday i Ajibefun Igbekele Amos. "Climate Variability on Fishing Activities in Inland Waters: Case of Owena River in Ondo and Osun States, Nigeria". W African Handbook of Climate Change Adaptation, 1919–36. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_91.
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AbstractThis chapter examined the effects of climate variability on fishing activities in inland waters: the case of Owena River in Ondo and Osun States, Nigeria. The particular inland water body (Owena) was selected purposively because the Owena River crosses across the two States (Ondo and Osun States). A total of 100 respondents/fisher folks were selected randomly. Primary data was used to get information from the respondents with the aid of the structured questionnaire. Secondary data was used to get information on the climate variability existing in the locations in order to achieve the set objectives. Specifically, the effects of climatic variables such as temperature, rainfall, and wind were determined on fisher folk, fishing duration, fish catch, fishing techniques, and fishing equipment/gears. Descriptive survey design was used to examine the demographic characteristics of respondents. The result revealed that most of the respondents (96%) were male. This chapter established that climate variability particularly strong wind, rainfall, and temperature has adverse effects on fishing activities such as reduction in fish catch, long duration of fishing, loss of fishing gear, change in fishing techniques, and effect on health; hence, the livelihoods of the residence are adversely affected on the long run. In addition to the adverse effect of poverty and loss of life for the fisher folks. Although, the fisher folks livelihoods depend mainly on fisheries resources and optimum fishing depends on favorable climate/weather conditions. Therefore, proper preventive coping strategies against the adverse effect of climate variables should be paramount in both States (Ondo and Ekiti) to improve livelihoods and food security.
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Lydia, Adeleke Mosunmola, Jacob Victor Jerry, Desalegn Yayeh Ayal, Akinola Joshua Oluwatobi, Ayodele Idowu Sunday i Ajibefun Igbekele Amos. "Climate Variability on Fishing Activities in Inland Waters: Case of Owena River in Ondo and Osun States, Nigeria". W African Handbook of Climate Change Adaptation, 1–18. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-42091-8_91-1.
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AbstractThis chapter examined the effects of climate variability on fishing activities in inland waters: the case of Owena River in Ondo and Osun States, Nigeria. The particular inland water body (Owena) was selected purposively because the Owena River crosses across the two States (Ondo and Osun States). A total of 100 respondents/fisher folks were selected randomly. Primary data was used to get information from the respondents with the aid of the structured questionnaire. Secondary data was used to get information on the climate variability existing in the locations in order to achieve the set objectives. Specifically, the effects of climatic variables such as temperature, rainfall, and wind were determined on fisher folk, fishing duration, fish catch, fishing techniques, and fishing equipment/gears. Descriptive survey design was used to examine the demographic characteristics of respondents. The result revealed that most of the respondents (96%) were male. This chapter established that climate variability particularly strong wind, rainfall, and temperature has adverse effects on fishing activities such as reduction in fish catch, long duration of fishing, loss of fishing gear, change in fishing techniques, and effect on health; hence, the livelihoods of the residence are adversely affected on the long run. In addition to the adverse effect of poverty and loss of life for the fisher folks. Although, the fisher folks livelihoods depend mainly on fisheries resources and optimum fishing depends on favorable climate/weather conditions. Therefore, proper preventive coping strategies against the adverse effect of climate variables should be paramount in both States (Ondo and Ekiti) to improve livelihoods and food security.
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Ishikawa-Ishiwata, Yuki, i Jun Furuya. "Economic Evaluation and Climate Change Adaptation Measures for Rice Production in Vietnam Using a Supply and Demand Model: Special Emphasis on the Mekong River Delta Region in Vietnam". W Interlocal Adaptations to Climate Change in East and Southeast Asia, 45–53. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-81207-2_4.
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AbstractVietnam is one of the most affected countries in terms of monetary losses or mortality of extreme events due to climate change in the world. Since agriculture is directly affected by the climate conditions in Vietnam, several adaptation measures such as shifting transplanting dates and/or using different cultivars have been taken to mitigate the loss of rice production because of climate change. In this chapter, we introduce the econometric evaluation methods of the adaptation measures with the supply and demand models. The supply and demand models each consist of yield, planted area, exports, imports, stock changes, and food demand functions of rice. By measuring the yield and planted area functions with climate variables, the effect of climate change on future rice production and food demand can be estimated. By inserting a mathematical model of dissemination of new cultivars, the possible outlook of the adaptation measure can be assessed as scenarios. In the case of the Mekong Delta Region, farmers in the coastal to central areas have been shifting the aquaculture-based farming style. We also discuss these transitions of farming style.
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Kafaei, Mohsen, Jane Burry, Mehrnoush Latifi i Joseph Ciorciari. "Designing a Systematic Experiment to Investigate the Effect of Ambient Smell on Human Emotions in the Indoor Space; Introducing a Mixed-Method Approach". W Computational Design and Robotic Fabrication, 235–47. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8405-3_20.
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AbstractStudies have indicated that built environments affect all aspects of human life such as emotion, perception, behavior, health, and well-being (Cooper et al. 2011). Built environments are formed from the combination and juxtaposition of visible and invisible environmental variables. In recent years, common techniques such as virtual reality, augmented reality, digital twins, and artificial intelligence have enabled researchers in the field of architecture and urban design to simulate environmental conditions to investigate the impacts of environmental variables on humans. However, the studies conducted in this field of human comfort are mostly focused on the impact of environmental variables such as form, temperature, humidity, and sound, and in fewer studies, up-to-date methods and technologies have been used to simulate and investigate the impact of smell on humans. Most of the studies that have investigated the effect of ambient smell on humans, carried out in the discipline of architecture and urban design, have used traditional tools and methods (questionnaire, interview, observation) rather than advanced technology and tools drawing on neuroscientific knowledge and technique to measure the effectiveness of the ambient smell on human. They have used unmasked scents or real-world environments rather than being able to simulate environmental conditions. This article highlights the significance and necessity of employing simulation methods to investigate the impact of environmental smells on humans. Additionally, it presents the methodology of an experiment for studying the effect of indoor environment smells (with a case study of an office environment in the initial phases) on human emotions, utilizing a mixed-method approach. Analysis of some parts of the data from this experiment showed that exposure to the fragrance of the jasmine flower pleasant (flower) and the odor of the rotten orange peel (unpleasant) can cause changes in the electroencephalography (EEG) power across different bands among participants.
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Konovalov, Dmytro, Eugeniy Trushliakov, Mykola Radchenko, Halina Kobalava i Vitaliy Maksymov. "Research of the Aerothermopressor Cooling System of Charge Air of a Marine Internal Combustion Engine Under Variable Climatic Conditions of Operation". W Lecture Notes in Mechanical Engineering, 520–29. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40724-7_53.
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Calì, Michele, Salvatore Massimo Oliveri i Marco Evangelos Biancolini. "Thread Couplings Stress Analysis by Radial Basis Functions Mesh Morphing". W Lecture Notes in Mechanical Engineering, 114–20. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_19.
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AbstractTraditional analytical methods are approximate and need to be validated when it comes to predict the tensional behavior of thread coupling. Numerical finite element simulations help engineers come up with the optimum design, although the latter depends on the constraints and load conditions of the thread couplings which are often variable during the system functioning. The present work illustrates a new method based on Radial Basis Functions Mesh Morphing formulation to optimize the stress concentration in thread couplings which is subject to variable loads and constraints. In particular, thread root and fillet under-head drawings for metric ISO thread, which are the most commonly used thread connection, are optimized with Radial Basis Functions Mesh Morphing. In metric ISO threaded connection, the root shape and the fillet under the head are circular, and from shape optimization for minimum stress concentration it is well known that the circular shape becomes seldom optimal. The study is carried out to enhance the stress concentration factor with a simple geometric parameterization using two design variables. Radial Basis Functions Mesh Morphing formulation, performed with a simple geometric parameterization, has allowed to obtain a stress reduction of up to 12%; some similarities are found in the optimized designs leading to the proposal of a new standard. The reductions in the stress are achieved by rather simple changes made to the cutting tool.
Streszczenia konferencji na temat "Conditions de charge variables"
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Aitio, Antti, i David Howey. "Combining Non-Parametric and Parametric Models for Stable and Computationally Efficient Battery Health Estimation". W ASME 2020 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/dscc2020-3180.
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Abstract Equivalent circuit models for batteries are commonly used in electric vehicle battery management systems to estimate state of charge and other important latent variables. They are computationally inexpensive, but suffer from a loss of accuracy over the full range of conditions that may be experienced in real-life. One reason for this is that the model parameters, such as internal resistance, change over the lifetime of the battery due to degradation. However, estimating long term changes is challenging, because parameters also change with state of charge and other variables. To address this, we modelled the internal resistance parameter as a function of state of charge and degradation using a Gaussian process (GP). This was performed computationally efficiently using an algorithm [1] that interprets a GP to be the solution of a linear time-invariant stochastic differential equation. As a result, inference of the posterior distribution of the GP scales as 𝒪(n) and can be implemented recursively using a Kalman filter.
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Kivelä, Tuomo, i Jouni Mattila. "Internal Leakage Fault Detection for Variable Displacement Axial Piston Pump". W ASME/BATH 2013 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fpmc2013-4445.
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In mobile machines, reliable condition monitoring (CM) of hydraulic system would be very beneficial because it could decrease the maintenance costs in case of a failure. It should also foresee potentially harmful, slight defects in the system, before they lead to system downtime. Very often the focus of the CM is in short term performance. For example, a neural network-based CM solutions require an extensive data collection and teaching phase. A model-based CM on the other hand an accurate model of the process which is tuned into a known operation points. However, it is typical that the operation conditions change. As a result, the process models become outdated and cause-action definitions do not apply to the changed situation. Therefore, a new model structure, Multi-Variable Histogram (MVH), for CM purposes is introduced. The MVH model is statistical nonlinear model of variable relations. The model is based on schematics where the system operation point changes are taken into account. The system input variables, as explanatory variables, define the operation point for the variable being observed. When the effects of the system input variables excluding faults are taken into account, faults can be seen as operation point changes. MVH model based CM solution includes the key elements of a long-term manageable CM solution. Furthermore, the experimental tests are carried-out with a variable displacement axial piston pump to verify the performance of the solution.
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Haber, Benjamin, i Junmin Wang. "Robust Control Approach on Diesel Engines With Dual-Loop Exhaust Gas Recirculation Systems". W ASME 2010 Dynamic Systems and Control Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/dscc2010-4135.
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This paper presents a robust control approach to achieve an independent control authority over the intake manifold conditions of a medium-duty, V8, Diesel engine with the use of a complex air-path system. The intake manifold conditions in question include gas temperature, pressure, and oxygen mass fraction. The purpose of achieving such a high control authority over these intake manifold conditions is to explore the possibilities of extending the operating ranges of advanced combustion modes like low temperature diffusion combustion (LTDC), homogenous charge compression ignition (HCCI), and pre-mixed charge compression ignition (PCCI). Independent control of these air-path variables is made possible by using a dual-loop exhaust gas recirculation (EGR) system with a two-stage, variable geometry turbocharging (VGT) system. A multi-input-multi-output robust air-path controller was designed based on a control-oriented model identified using a high-fidelity GT-Power model of a medium-duty Diesel engine. Simulation results illustrate the effectiveness of the controller over a limited engine operating range.
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Cagan, Jonathan, i Brian C. Williams. "First-Order Necessary Conditions for Robust Optimality". W ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0344.
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Abstract The first-order necessary conditions of optimality are extended to include information about robust design — cost insensitivity to model inaccuracies and changes in design specification, as well as the manufacturing tolerances treated in more traditional approaches. In these extended conditions, the Lagrangian is formulated as a tradeoff between cost and cost variability, where variability is measured as the flatness and curvature of the objective relative to local variations in design variables and constraints. During optimization these conditions allow cost and robustness to be considered simultaneously at each iteration.
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Zavadinka, Peter, i Robert Grepl. "Energy Saving Potential of a Hydrostatic Drivetrain With Variable Charge Pump". W 8th FPNI Ph.D Symposium on Fluid Power. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fpni2014-7844.
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This paper deals with the power saving prediction of hydrostatic drivetrains achieved with a variable roller charge pump. Focusing on the charge pump in a hydrostatic transmission, shows, that fixed pumps don’t act in all operating conditions very efficient. The charge pump delivers in some conditions a higher flow than required. The unused energy is dissipated into heat. According to this assumption, using variable charge pump is another possible way to save energy. In the end it means reduce fuel consumption. Generally, the power saving potential is depending on the application, but two main factors can be highlighted: the first one is the charge pump size and the second is the application of an intelligent loop flushing system. The standard loop flushing system demands more cooling flow than required in some conditions, but a variable charge pump is able to more efficiently cover demands of intelligent loop flushing system. The power saving potential will be analyzed for two different example systems/vehicles in their typical operation conditions. All analyses are made with simulation models, which include simplified thermal behavior of the hydraulic circuit, also. The results in this paper confirmed the power saving potential for different applications with bigger charge pumps with an intelligent loop flushing function could be the most interesting applications.
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Zhou, Xin, Jeffrey L. Stein i Tulga Ersal. "Battery State of Health Monitoring by Estimation of the Number of Cyclable Li-Ions". W ASME 2016 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/dscc2016-9730.
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This paper introduces a method to monitor battery state of health (SOH) by estimating the number of cyclable Li-ions, a health-relevant electrochemical variable. SOH monitoring is critical to battery management in particular for balancing the trade-off between maximizing system performance and minimizing battery degradation. However, SOH-related electrochemical variables cannot be directly measured non-invasively. Hence, estimation algorithms are needed to track those variables non-destructively while the battery is in use. In this paper, the extended Kalman filter (EKF) is used to estimate the number of cyclable Li-ions as an unknown battery parameter. Simulations are performed using an example parameter set for a hybrid-electric-vehicle battery whose cathode material is LiMn2O4 mixed with other Li-compounds to obtain estimation results under a typical electric vehicle current profile that consists of a 1 C constant current charge mode and a discharge current profile for an electric vehicle subject to the Urban Dynamometer Driving Schedule cycle. The simulations show promising results in estimation of the number of cyclable Li-ions using the EKF under the ideal conditions. Next, robustness of the algorithm under non-ideal conditions (i.e., with SOC estimation error, modeling error, and measurement noise) is analyzed, and it is shown that estimation of the number of cyclable Li-ions using the EKF preserves high accuracy even under these non-ideal conditions. The proposed estimation technique for the number of cyclable Li-ions can also be applied to other parameter sets and batteries with other cathode materials to monitor the SOH change resulting from any degradation mechanism that consumes cyclable Li-ions.
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Nobari, Soroush, Rosaire Mongrain, Ian Campbell, Richard Leask i Raymond Cartier. "Derivation of Surrogate Variables to Assess Pathological Conditions Using a 3D Model of the Aortic Valve". W ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-205087.
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The aortic valve has received much attention in the biomedical research community during recent years. As a critical part of the cardiovascular system, any alteration in its structure or in the surrounding area directly or because of pathologies would change the flow pattern of that region as a consequence. Numerous studies have been done and regardless of the approach, the aim of all these studies is the same: to understand the intricacies of the healthy aortic valve and, perhaps, to mimic it in the realm of prosthetics.
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Krikkis, Rizos N., Stratis V. Sotirchos i Panagiotis Razelos. "Bifurcation Analysis for Horizontal Longitudinal Fins Under Multi-Boiling Conditions". W ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33632.
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A numerical bifurcation analysis is carried out in order to determine the solution structure of a fin subject to multi-boiling heat transfer mode. The thermal analysis can no longer performed independently of the working fluid since the heat transfer coefficient is temperature dependent and includes the nucleate, the transition and the film boiling regime where the boiling curve is obtained experimentally for a specific fluid. The heat transfer process is modeled using one-dimensional heat conduction with or without heat transfer from the fin tip. Furthermore, five fin profiles are considered: the constant thickness, the trapezoidal, the triangular, the convex parabolic and the parabolic. The multiplicity structure is obtained in order to determine the different types of bifurcation diagrams, which describe the dependence of a state variable of the system (for instance the fin temperature or the heat dissipation) on a design (CCP) or operation parameter (base TD). Specifically the effects of the base TD, of CCP and of the Biot number are analyzed and presented in several diagrams since it is important to know the behavioral features of the heat rejection mechamism such as the number of the possible steady states and the influence of a change in one or more operating variables to these states. Stability analysis is carried out using the “resonance integral” technique and the Sturm-liouville eigen system analysis.
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Nour Eldin, H. A., i I. El-Nashar. "A Micro State Dynamic Model and Compatibility Conditions for the One Dimensional Non-Stationary Compressible Flow in Pressure Wave Machines". W ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62549.
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Shock tube like applications such as the pressure wave machines are subjected to the possible build up of moving discontinuities in the material, temperature and pressure. The method of characteristics offered a suitable platform to take these aspects into consideration. Jenny [1,2,3] has applied this method to obtain the direction and the corresponding compatibility conditions for the isentropic non-stationary one dimensional gas flow. Following Jenny’s derivation, it was possible to derive the general compatibility conditions [4–8] along the corresponding characteristic directions. The variable grid method [4–8] used a second order approximation of the direction and compatibility conditions. A system of non-linear equations [4–8] for the local states and the grid positions was obtained. In spite of the accurate results achieved by the variable grid method, the obligation to grid reorganization -while numerically tractable- have drawn the attention to the possibility that there may be persistent and inherent analytical/physical inadequacy with respect to the resulting compatibility equations that are numerically reflected by inhomogeneous build up of the variable grid. This paper, therefore, revisits the formulation of the dynamics of the one dimensional non stationary compressible flow and develops a new micro state dynamic model. The micro state equations of continuity, momentum and energy are derived. A micro state variable such as Θ or P represents the micro state dynamics, while the corresponding flow variables of temperature T or density ρ are to be regarded as observed measurement variables. Further, the micro state compatibility conditions are derived. The resulting micro state total differentials dS0 & dS± along the particle path & sound propagation ± Lines are linear functions of the micro state differentials. It is shown that dS0 is the total differential of the micro state energy equation along the particle path. It is proportional to the “Clausius”-entropy differential ds through the gas constant R and to the differential of the number of micro states dΩ* in “Boltzmann”-relation by the Avogadro number NA. For isentropic flow, dS± is proportional — through κ and the sound speed a — to the transformed micro state “Riemann”-differential dR±. Otherwise, the relation ±ΔbaR± = [Δ,baS± + ΔbaS0] holds along the ± Lines where ±ΔbaR± & ΔbaS± are the weighted change of the micro state differential of Riemann-Invariants and the change of dS± along the ± Lines respectively. δ baS0 is the “jump” along the ± Lines of dS0. Beside providing novel micro state compatibility conditions for the variable grid method, the presented formulation clears the existence as well as the sign of entropy change (reversibility/irreversibility) within the second law of thermodynamics.
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Nguyen, Ducduy, Renston Fernandes i James W. G. Turner. "Variable Compression Ratio Hydrogen-Fueled Homogeneous Charge Compression Ignition Engine". W 16th International Conference on Engines & Vehicles. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-24-0067.
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<div class="section abstract"><div class="htmlview paragraph">Hydrogen-fueled homogeneous charge compression ignition (HCCI) engines have shown the ability to provide a cleaner and more efficient alternative to conventional fossil fuels. The use of hydrogen as a fuel has the potential to reduce greenhouse gas and promote sustainability.</div><div class="htmlview paragraph">In this study, a modified single-cylinder Cooperative Fuel Research (CFR) engine was utilised to operate on hydrogen in a HCCI combustion mode under various compression ratio (CR) conditions. In the experiments, the amount of hydrogen injected was adjusted at each CR to maintain the crank angle at 50% mass fraction burned (CA50) combustion phasing at 3±1 crank angle degrees after top dead center or as lean as possible. The engine speed was fixed at 600 rpm, and the impact of different intake air temperatures was also investigated.</div><div class="htmlview paragraph">The results indicated that as the compression ratio increases, the air-fuel ratio needs to be increased to maintain the desired CA50 value, i.e., the engine needs to operate leaner. The net indicated mean effective pressure of the engine reached a value of 2.9 bar at a compression ratio of 14 and an intake air temperature of 150<sup>O</sup>C. The effects of CR and intake temperature on engine performance metrics, such as power output and the rate of heat release, were also investigated. The experimental data showed that the intake air temperature did not have a significant effect on engine performance and power output. At a compression ratio of 16:1 and 600 rpm, the engine's indicated thermal efficiency was found to be approximately 33% across the range of intake temperatures investigated. Furthermore, the fact that the engine effectively produced zero NOx emissions under the various CR conditions tested further highlights the potential for hydrogen HCCI engines to be adopted as a cleaner and more efficient alternative to internal combustion engines using conventional fuels, provided the available range of operation is acceptable and can be made large enough for practical applications.</div></div>
Raporty organizacyjne na temat "Conditions de charge variables"
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Behrman, Jere R., Miguel Székely i Suzanne Duryea. Schooling Investments and Aggregate Conditions: A Household Survey-Based Approach for Latin America and the Caribbean. Inter-American Development Bank, listopad 1999. http://dx.doi.org/10.18235/0010768.
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Schooling is a major factor in economic development. There is extensive empirical literature on what determines schooling attainment. But most of this literature uses micro data to explore connections between schooling attainment and family background and experiences, local markets, local schools and other community characteristics. These studies generally have not linked schooling attainment closely to changes in aggregate economic conditions. This paper uses a new high quality data set for 18 Latin American and Caribbean countries to assess the effects of macro conditions on schooling attainment. Household survey data are used to construct a quasi panel with information on attainment for birth cohorts born between 1930 and 1970, which is merged with country-specific aggregate data. We use the data to document schooling progress in Latin America and estimate multivariate relations for schooling attainment by birth cohorts as related to sets of variables for macroeconomic stability, factor endowments, demographic developments, institutions and culture and religion. These estimates are used to decompose the change in schooling progress by decade, and to explore the causes of the slowdown in schooling accumulation in the region since the 1980s debt crisis.
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Matthews, Stephen N., Louis Iverson, Matthew Peters i Anantha Prasad. Assessing potential climate change pressures across the conterminous United States. United States Department of Agriculture Forest Service, marzec 2018. http://dx.doi.org/10.32747/2018.6941248.ch.
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The maps and tables presented here represent potential variability of projected climate change across the conterminous United States during three 30-year periods in this century and emphasizes the importance of evaluating multiple signals of change across large spatial domains. Maps of growing degree days, plant hardiness zones, heat zones, and cumulative drought severity depict the potential for markedly shifting conditions and highlight regions where changes may be multifaceted across these metrics. In addition to the maps, the potential change in these climate variables are summarized in tables according to the seven regions of the fourth National Climate Assessment to provide additional regional context. Viewing these data collectively further emphasizes the potential for novel climatic space under future projections of climate change and signals the wide disparity in these conditions based on relatively near-term human decisions of curtailing (or not) greenhouse gas emissions.
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Tarif, Kheira. Climate Change and Violent Conflict in West Africa: Assessing the Evidence. Stockholm International Peace Research Institute, luty 2022. http://dx.doi.org/10.55163/vhiy5372.
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West Africa is widely cited as a hotspot of climate change and insecurity. This SIPRI Insights uses a systematic literature review of academic research to build a better understanding of the relationship between climate change and violent conflict in the region. Its findings are structured around four established ‘pathways’ of climate insecurity: (a) worsening livelihood conditions; (b) increasing migration and changing pastoral mobility patterns; (c) tactical considerations by armed groups; and (d) elite exploitation of local grievances. The literature review highlights a number of important variables in the relationship between climate change and violent conflict in West Africa: maladaptation to livelihood insecurity; migration away from climate-exposed areas; escalating farmer–herder conflicts; and sometimes weak, sometimes divisive, sometimes exploitative governance. Despite these findings, the literature review reveals current research and policy discussions on climate change and violent conflict in West Africa are informed by a very limited amount of academic research.
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Goldhaber, A. S. Fractional Charge Definitions and Conditions. Office of Scientific and Technical Information (OSTI), czerwiec 2004. http://dx.doi.org/10.2172/826963.
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Agüero, Jorge M., i Verónica Frisancho. Systematic Bias in Sensitive Health Behaviors and Its Impact on Treatment Effects: An Application to Violence against Women. Inter-American Development Bank, kwiecień 2017. http://dx.doi.org/10.18235/0007031.
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Violence against women takes place mainly in the private sphere and isperpetrated by people close to the victim. These features can introduce large biases into its reporting in specialized surveys as well as to the authorities. We test for the existence of measurement error in the reporting of such violence using experimental methods in Peru, a country with several specialized surveys but one lacking reliable administrative data. We ask women to report past experiences of violent acts by randomly assigning them one of two questionnaires, one that replicates current surveys and another that relies on list experiments to provide a more private setting. We find no significant reporting bias on average. However, we uncover strong evidence of non-random measurement error by education level. For highly educated women, an increase in privacy leads to higher reporting of violence, while no change is observed for the less educated. The increase is large enough to reverse the education gradient in violence. We discuss how nonclassical error in the outcome variable affects the estimation of the role of risk factors on violence. In particular, randomized controlled trials underperform instrumental variables estimates and, under certain conditions, the former could lead to even larger biases compared to cross-sectional studies.
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Shiu, Ji-Liang, i Yingyao Hu. Nonparametric identification using instrumental variables: sufficient conditions for completeness. Institute for Fiscal Studies, czerwiec 2011. http://dx.doi.org/10.1920/wp.cem.2011.2511.
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Gohin, Alex, i Thomas Hertel. A Note on the CES Functional Form and Its Use in the GTAP Model. GTAP Research Memoranda, październik 2003. http://dx.doi.org/10.21642/gtap.rm02.
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The purpose of this note is to provide an exhaustive reference for those interested in learning more about the Constant Elasticity of Substitution (CES) function and its use in the representation of producer behavior in the GTAP model. Particular attention is paid to the role of technical change variables and their effect on cost minimizing demands and input shares. This note is divided into three sections. In the first section, the basic cost minimization problem is laid out and conditional factor demands, as well as the unit cost function, are derived. In section two, this system of equations is expressed in terms of proportional changes, as currently specified in GTAP. This greatly facilitates decomposition of predicted changes in demands and costs between three effects, namely expansion, substitution, and technical change effects. Section two also shows the relationship between changes in cost shares and changes in prices and factor-biased technical change variables. Finally, section three relates these derivations to the notation employed in GTAP.
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Freund, F. Charge distribution analysis of catalysts under simulated reaction conditions. Office of Scientific and Technical Information (OSTI), styczeń 1992. http://dx.doi.org/10.2172/6850561.
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Day, Christopher M., Hiromal Premachandra i Darcy M. Bullock. Characterizing the Impacts of Phasing, Environment, and Temporal Factors on Pedestrian Demand at Traffic Signals. Purdue University, 2011. http://dx.doi.org/10.5703/1288284317352.
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There is a need for more and higher quality data on pedestrian demand patterns for a number of applications in planning, transportation engineering, public health, and other areas. It is particularly desirable to better characterize the influence of daily, weekly, and annual variations; the impact of weather and special events; and the effects of changes in pedestrian phasing. This paper proposes and demonstrates a methodology for quantifying the relative demand for pedestrian service at a signalized intersection by using the percent of signal cycles per hour in which the pedestrian phase was actuated. Although this performance measure does not by itself provide a pedestrian count, it can be used as a surrogate to characterize how pedestrian volumes vary due to operating conditions. More importantly, since this technique does not require new sensors, the data can be collected at thousands of intersections across the nation where pedestrian push buttons are in use. This paper documents findings from over a year of data collection at a signalized intersection on a college campus. The effects of daily/weekly/annual variations, special events, weather (temperature and precipitation), seasonal changes in activity patterns, and changes in pedestrian signal phasing are documented. A Tobit model is used to account for the influences of these variables and understand how they co-influence pedestrian activity. The implementation of an exclusive pedestrian phase is associated with a 9% increase in pedestrian phase utilization at the intersection. This change is associated with a decrease in user cost relative to performing midblock crossings. The modeled impact of snowfall events adds further insight by showing that as the user cost of making midblock crossings increases, pedestrian activity at the intersection increases.
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Vargas, Fernando, Gustavo Crespi i Ezequiel Tacsir. Innovation and Productivity in Services: Empirical Evidence from Latin America. Inter-American Development Bank, sierpień 2014. http://dx.doi.org/10.18235/0009215.
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This paper analyzes and compares the determinants of innovation in the service industry and its impact on labor productivity at the firm level in three countries of Latin America (Chile, Colombia, and Uruguay). The main findings show that, similar to what is observed in manufacturing industry, service firms that invest the most in innovation activities are more likely to introduce changes or improvements in their production process and/or product mix, and those firms that innovate have higher labor productivity than non-innovative firms. Size was found to be a less relevant determinant of innovation in services than in manufacturing, suggesting that the need for infrastructure and associated sunk costs are lower in services. Conversely, cooperation was found to be far more important for innovation in services than in manufacturing, in line with the more interactive nature of innovation in services. Yet, large differences in statistical significance and size of the coefficients of explanatory variables among the countries studied suggest that the framework conditions where a firm operates have an important role in innovation decisions.