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Search Results: 1 - 10 of 116 matches for " Costanza "
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Estimating pure diffusion contributions in alkaline pulping processes
Costanza,Vicente; Costanza,Pedro;
Latin American applied research , 2002,
Abstract: a model that predicts isothermal alkali diffusion and reaction with acetyl groups in moist wood chips was derived and approximated. system parameters were estimated from unsteady-state experimental data. simulation results reinforce the idea that the diffusion effect is not fully exploited in pulping processes. traditionally, digestion is conducted at high temperature, where delignification reaction kinetics is enhanced and the reaction effect is predominant. this approach is being reviewed by modern industry since energy and environmental savings associated with low temperature operation might compensate for high-yield productivity. the concentration of alkali at the center of the chip is a measure of the completeness of wood deacetylation, which translates into the aptitude of the final product for pulping purposes. this concentration is predicted here from the solution to a pair of coupled ode's. since alternatives combining both low and high-temperature processes are being studied, the results in this paper provide basic data for optimization analysis.
Estimating pure diffusion contributions in alkaline pulping processes
Vicente Costanza,Pedro Costanza
Latin American applied research , 2002,
Abstract: A model that predicts isothermal alkali diffusion and reaction with acetyl groups in moist wood chips was derived and approximated. System parameters were estimated from unsteady-state experimental data. Simulation results reinforce the idea that the diffusion effect is not fully exploited in pulping processes. Traditionally, digestion is conducted at high temperature, where delignification reaction kinetics is enhanced and the reaction effect is predominant. This approach is being reviewed by modern industry since energy and environmental savings associated with low temperature operation might compensate for high-yield productivity. The concentration of alkali at the center of the chip is a measure of the completeness of wood deacetylation, which translates into the aptitude of the final product for pulping purposes. This concentration is predicted here from the solution to a pair of coupled ODE's. Since alternatives combining both low and high-temperature processes are being studied, the results in this paper provide basic data for optimization analysis.
Optimal state-feedback regulation of the hydrogene evolution reactions
Costanza,V.;
Latin American applied research , 2005,
Abstract: a control strategy is developed in order to keep processes based on the hydrogen evolution reactions (her) near operational steady states. the problem is treated in the context of optimal control for nonlinear systems subject to quadratic cost objectives. the original dynamics is shown to be accurately approximated by a bilinear model without increasing the dimension, so the state variables retain their physical meaning. finite and infinite horizon optimal control strategies are developed, based on the hamiltonian formalism, and introducing a novel approach for working on-line with generalized riccati differential equations and the associated costate dynamics. when there exists a final penalty on the state deviation, then a first order quasi-linear partial differential equation is discovered and solved for the riccati matrix. the observability problem is also treated, since the natural state (electrode surface coverage) can not be measured continuously. the output variable (current density) is fed into a high-gain nonlinear observer based on lyapunov's stability considerations. the whole approach allows for (in general time-dependent) state-feedback control.
Visions of Alternative (Unpredictable) Futures and Their Use in Policy Analysis
Robert Costanza
Ecology and Society , 2000,
Abstract: The most critical task facing humanity today is the creation of a shared vision of a sustainable and desirable society, one that can provide permanent prosperity within the biophysical constraints of the real world in a way that is fair and equitable to all of humanity, to other species, and to future generations. Recent work with businesses and communities indicates that creating a shared vision is the most effective engine for change in the desired direction, yet most effort in "futures modeling" has focused on extrapolating past trends rather than envisioning alternative futures. Science and economics as applied to policy are in conflict more often over alternative visions of the world than purely "scientific" disagreements. Likewise, governance has gotten bogged down in mediating short term conflicts between special interests rather than its more basic role of creating broadly shared visions that can guide dispute resolution. This paper addresses the question of what policies are most appropriate for society now, given alternative visions of the future and the enormous uncertainty about the reality of the assumptions underlying these visions. Four specific visions are laid out as being representative of the major alternatives. For each vision the benefits of achieving the vision, the assumptions that would have to be true in order for it to be achieved, and the implications of it being attempted but not achieved are explored. It is argued that dealing with uncertainty about the nature of the world, its carrying capacity for humans, the impacts of climate change, and other aspects of its future can best be done at this level of future visions and assumptions, not at more detailed levels (like the parameter uncertainty in models). Application of this vision/uncertainty analysis can help us both to design the future society we want and to maximize the chances of our getting there safely.
Optimal state-feedback regulation of the hydrogene evolution reactions
V. Costanza
Latin American applied research , 2005,
Abstract: A control strategy is developed in order to keep processes based on the hydrogen evolution reactions (HER) near operational steady states. The problem is treated in the context of Optimal Control for nonlinear systems subject to quadratic cost objectives. The original dynamics is shown to be accurately approximated by a bilinear model without increasing the dimension, so the state variables retain their physical meaning. Finite and infinite horizon optimal control strategies are developed, based on the Hamiltonian formalism, and introducing a novel approach for working on-line with generalized Riccati differential equations and the associated costate dynamics. When there exists a final penalty on the state deviation, then a first order quasi-linear partial differential equation is discovered and solved for the Riccati matrix. The observability problem is also treated, since the natural state (electrode surface coverage) can not be measured continuously. The output variable (current density) is fed into a high-gain nonlinear observer based on Lyapunov's stability considerations. The whole approach allows for (in general time-dependent) state-feedback control.
MicroRNAs in Postischemic Vascular Repair
Andrea Caporali,Costanza Emanueli
Cardiology Research and Practice , 2012, DOI: 10.1155/2012/486702
Abstract: The term angiogenesis describes the growth of endothelial sprouts from preexisting postcapillary venules. More recently, this term has been used to generally indicate the growth and remodeling process of the primitive vascular network into a complex network during development. In adulthood, angiogenesis is activated as a reparative process during wound healing and following ischemia, and it plays a key role in tumor growth and metastasis as well as in inflammatory diseases and diabetic retinopathy. MicroRNAs (miRNAs) are endogenous, small, noncoding RNAs that negatively control gene expression of target mRNAs. In this paper, we aim at describing the role of miRNAs in postischemic angiogenesis. First, we will describe the regulation and the expression of miRNAs in endothelial cells. Then, we will analyze the role of miRNAs in postischemic vascular repair. Finally, we will discuss the role of circulating miRNAs as potential biomarkers in ischemic diseases. 1. Introduction Postnatal neovascularization occurs in pathological diseases, including diabetic retinopathy, arthritis, and tumor growth and metastasis, as well as during wound healing and postischemic repair [1]. Following occlusion of a major artery, two different types of vascular regrowth responses are activated to contrast the ischemic condition and salvage of injured ischaemic tissue: sprouting of capillaries (angiogenesis) and growth of collateral arteries from preexisting arterioles (arteriogenesis) [2]. Angiogenesis is the process of growth of endothelial sprouts from preexisting postcapillary venules. It is initiated by the vasodilation of venules leading to increased permeability, followed by the proliferation and migration of endothelial cells (ECs). Then, venules are divided by periendothelial cells (intussusception) or are separated by transendothelial cell bridges (bridging) to form capillaries [3, 4]. Arteriogenesis was originally defined as the process of collateral arteries formation which follows the occlusion of a major artery [5]. Arteriogenesis is partly driven by shear stress and involves the proliferation and migration of vascular endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). It leads to the production of mature arteries with a fully developed tunica media, which may provide alternative blood perfusion to ischemic areas [6]. microRNAs (miRNAs) are inhibitory regulators of gene expression which act by binding to complementary messenger RNA (mRNA) transcripts. Following initial studies in developmental biology and cancer, miRNAs have recently come into focus of
Riflettendo sull’andare a piedi Thinking about Going on Foot
Costanza Caniglia Rispoli
TeMA : Journal of Land Use, Mobility and Environment , 2008,
Abstract: La mobilità pedonale non è che una componente della mobilità, fenomeno tramite cui una società si “impadronisce” del proprio territorio. Da tempo mobilità è sinonimo di traffico e circolazione ed è classico tema ingegneristico di pianificazione dei trasporti, mentre già con la Carta di Atene è una della quattro funzioni base dell’insediamento umano. Nella cultura più avanzata oggi l’attenzione in campo urbanistico converge sui perché della mobilità e in quello ingegneristico si è spostata dalla mobility-oriented analysis alla accessibility-based analysis. L’andare a piedi integra in modo determinante il sistema urbano dei trasporti. Ma spesso, non solo in Italia, c’è confusione sul concetto di pedone: nella classificazione delle strade urbane prevale una separazione rigida degli usi mentre piani dei trasporti e piani urbanistici restano operazioni separate. Interessanti esempi anche italiani dimostrano che perseguire migliori condizioni di vita in un territorio richiede attenzione ai problemi di mobilità unitamente a quelli di uso dello spazio. Occorre uno studio convergente tra competenze che vanno anche oltre trasporti e urbanistica e capire che c’è un rapporto ecologico tra soggetti e luoghi, tra società umane e ambiente della loro vita. The pedestrian mobility is only a component of mobility, a phenomenon through which a society “takes possession” of her territory. Since a long time mobility has become the synonym of traffic and circulation as well as the classic engineering subject of transport planning, while already in the Athens Charter it is considered one of the four basic functions of human settlement. In the most advanced culture, the attention is paid, from the town planning point of view, to the causes of mobility and in the engineering one it has been shifted from the mobility oriented- analysis to the accessibility-based analysis. Walking integrates the urban transport system in a crucial way. But often, not only in Italy, there is confusion about the concept of pedestrian: in the classification of urban roads there is a strict separation of the uses, while transport plans and town planning ones remain separate tools. Interesting examples, also of Italian case-studies, highlight that pursuing better conditions of life in a territory asks for attention to mobility problems together with those related to the use of space. There is a need for a study which would join competences that go also beyond transports and town planning and it is necessary to understand that there is an ecological relationship between people and places, between human
EL INTERéS SUPERIOR DEL NI O TRABAJADOR Y LA PROTECCIóN EFECTIVA DE SUS DERECHOS EN ARGENTINA
Paula Costanza Sardegna
Cognitio Juris : Revista Jurídica , 2012,
Abstract: RESUMOEn el marco de la Teoría General y la Filosofía del Derecho, el Derecho Constitucional y, en particular el Derecho del Trabajo, el desarrollo de la teoría y praxis de los Derechos Humanos, ha llevado a plasmar primero en el ámbito del Derecho Internacional y luego en las Constituciones locales una serie de compromisos tanto de garantías de protección de los ni os que implican no sólo la abstención por parte del Estado de actuar en perjuicio de aquéllos, sino también la obligación positiva de remover los obstáculos que interfieren en su desarrollo y de generar las condiciones para que éste florezca.El mundo de los ni os y adolescentes exige normas específicas e instituciones propias, dinámicas y permanentemente alertas a los cambios sociales que se generan.Esta presentación es un aporte para la reflexión que pone en evidencia el peligro que implica el vaciamiento conceptual del que puede ser víctima el principio del “interés superior del ni o” y todo lo que ello puede llegar a implicar en la tutela de los derechos del ni o, ni a, adolescente trabajador. Palavras- chave: Ni o, ni as y adolescentes, Derecho del Trabajo, Interés Superior del Ni o. THE INTERESTS OF THE CHILD LABOR AND EFFECTIVE PROTECTION OF RIGHTS IN ARGENTINA ABSTRACT As part of the General Theory and Philosophy of Law, Constitutional Law and in particular labor law, the development of theory and praxis of human rights has led to the first capture in the field of international law and then local constitutions in a series of commitments both guaranteed protection of children involve not only the abstention by the State to act to their detriment, but also a positive obligation to remove obstacles that interfere with their development and to generate the conditions for it to flourish.The world of children and adolescents requires specific rules and institutions, dynamic and constantly alert to the social changes that are generated.This presentation is a contribution to the reflection that highlights the danger of conceptual emptying may be a victim of the principle of "best interests" and all that it can imply in the protection of child rights , girl, young workers. Key-words: Children and adolescents, Labor Law, Interest of the Child. SUMáRIOI – INTRODUCCIóN. II - EL NI O COMO SUJETO DE DERECHO. III – TUTELA DEL NI O TRABAJADOR. IV – CONCEPTUALIZACIóN DEL INTERéS SUPERIOR DEL NI O. a) Designación y denotación de los términos. b) Designación. c) Denotación. d) Interpretación. V – CARACTERíSTICAS DEL PRINCIPIO DEL INTERéS SUPERIOR DEL NI O EN ARGENTINA. VI – DISCRECIONALIDAD NO REGLADA.
On the reproduction properties of non-stationary subdivision schemes
Costanza Conti,Lucia Romani
Mathematics , 2010,
Abstract: We present an accurate investigation of the algebraic conditions that the symbols of a convergent, univariate, binary, non-stationary subdivision scheme should fulfill in order to reproduce spaces of exponential polynomials. A subdivision scheme is said to possess the property of reproducing exponential polynomials if, for any initial data uniformly sampled from some exponential polynomial function, the scheme yields the same function in the limit. The importance of this property is due to the fact that several functions obtained as combinations of exponential polynomials (such as conic sections, spirals or special trigonometric and hyperbolic functions) are of great interest in graphical and engineering applications. Since the space of exponential polynomials trivially includes standard polynomials, the results in this work extend the recently developed theory on polynomial reproduction to the non-stationary context. A significant application of the derived algebraic conditions on the subdivision symbols is the construction of new non-stationary subdivision schemes with specified reproduction properties.
From full rank subdivision schemes to multichannel wavelets: A constructive approach
Mariantonia Cotronei,Costanza Conti
Mathematics , 2013,
Abstract: In this paper, we describe some recent results obtained in the context of vector subdivision schemes which possess the so-called full rank property. Such kind of schemes, in particular those which have an interpolatory nature, are connected to matrix refinable functions generating orthogonal multiresolution analyses for the space of vector-valued signals. Corresponding multichannel (matrix) wavelets can be defined and their construction in terms of a very efficient scheme is given. Some examples illustrate the nature of these matrix scaling functions/wavelets.
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