Quotient p-Schatten metrics on spheres

Let S(H) be the unit sphere of a Hilbert space H and Up(H) thegroup of unitary operators in H such that u−1 belongs to the p-Schatten idealBp(H). This group acts smoothly and transitively in S(H) and endows it witha natural Finsler metric induced by the p-norm kzkp = tr(zz∗)p/21/p. Thismetric is given bykvkx,p = min{kz − ykp : y ∈ gx},where z ∈ Bp(H)ah satisfies that (dπx)1(z) = z · x = v and gx denotes theLie algebra of the subgroup of unitaries which fix x. We call z a lifting of v.A lifting z0 is called a minimal lifting if additionally kvkx,p = kz0kp. Inthis paper we show properties of minimal liftings and we treat the problemof finding short curves α such that α(0) = x and ˙α(0) = v with x ∈ S(H)and v ∈ TxS(H) given. Also we consider the problem of finding short curveswhich join two given endpoints x, y ∈ S(H).Fil: Andruchow, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Antunez, Andrea. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentin

Fros, Weaves, and Kinks: The Social and Political Significance of Hair for Black and Coloured Women in Cape Town

This project seeks to explore and understand hair performance by black and coloured females in Cape Town and understand 1) its possible political significance and 2) its social role. This ISP will attempt to explore the construction of hair as a symbol of class and beauty by looking at its historical significance. In this paper, I will investigate how young women in Cape Town, specifically black and coloured women, choose to represent themselves through hair and explore the connotations attached to their particular hairstyle choice. Furthermore, in this paper I will try to answer the following questions 1) Do black women feel societal pressures to straighten their hair, 2) If, so, why? And 3) Do their personal choice in regards to their hair, whether natural or straightened, reflect any political or social stance or movement

EFFECT OF REDUCED SODIUM CHEESE ON THE GROWTH OF PATHOGENIC BACTERIA AND INACTIVATION OF LISTERIA INNOCUA USING SUPERCRITICAL FLUID EXTRACTION WITH CO2

Listeria monocytogenes continues to challenge the dairy industry in causing post-process contamination of cheeses. To reduce risk of contamination, it is crucial to understand the growth and survival of pathogenic bacteria in cheese products and to develop post-process mitigation strategies. This study evaluated the fate of pathogens in reduced and regular sodium Mozzarella cheese, and the potential of Supercritical Fluid Extraction with CO2 (SFE) to reduce Listeria innocua on Mozzarella and Queso Fresco. The survival of L. monocytogenes, Salmonella, and E.coli O157:H7 (2-3 log CFU/g) in reduced sodium Mozzarella (1.62%), compared to regular sodium Mozzarella cheese (2.15%) at 4ºC and 12ºC for 90 and 30 days, respectively, was evaluated. Salmonella and E. coli O157:H7 populations decreased over incubation time at both temperatures and no difference (pListeria monocytogenes population also decreased during incubation time at 4°C regardless of the sodium concentration in Mozzarella cheese. However, there was a difference in the population of L. monocytogenes for regular and reduced sodium incubated 12°C, and its populations increased 1 log CFU/g in reduced sodium Mozzarella cheese. Additionally, this study determined the bactericidal effect of SFE on the population of L. innocua, a surrogate for L. monocytogenes, in Mozzarella and Queso Fresco cheese (6 log CFU/g) treated with SFE at two pressures and temperatures (120 bar at 40°C and 150 bar at 50°C) for 30 min. SFE treatment at 120 bar, 40°C for 30 min decreased L. innocua by approximately 3.0 and 3.5 log CFU/g in Mozzarella and Queso Fresco cheeses, respectively. SFE at 150 bar and 50°C reduced L. innocua by approximately 3.78 and 5.2 log CFU/g in Mozzarella and Queso Fresco cheeses, respectively. Since SFE had a minimal effect on the physico-chemical characteristics of the cheeses assayed, the results suggest SFE might be used to reduce L. monocytogenes in cheeses without negatively impacting product quality

Design of nonlinear controllers through the virtual reference method and regularization

This work proposes a new extension for the nonlinear formulation of the data-driven control method known as the Nonlinear Virtual Reference Feedback Tuning. When the process to be controlled contains a significant quantity of noise, the standard Nonlinear VRFT approach – that uses the Least Squares method – yield estimates with poor statistical properties. These properties may lead the control system to undesirable closed loop performances and even instability. With the intention to improve these statistical properties and controller sparsity and hence, the system’s closed loop performance, this work proposes the use of ℓ1 regularization on the nonlinear formulation of the VRFT method. Regularization is a component that has been extensively employed and researched in the Machine Learning and System Identification communities lately. Furthermore, this technique is appropriate to reduce the variance in the estimates. A detailed analysis of the noise effect on the estimate is made for the Nonlinear VRFT method. Finally, three different regularization methods, the third one proposed in this work, are compared to the standard Nonlinear VRFT.Este trabalho propõe uma nova extensão para a formulação não linear do método de controle orientado por dados conhecido como Método da Referência Virtual Não Linear, ou Nonlinear Virtual Reference Feedback Tuning – denominado aqui somente como VRFT. Quando o processo a ser controlado contém uma quantidade significativa de ruído, a abordagem padrão do VRFT – que usa o método dos Mínimos Quadrados – fornece estimativas com propriedades estatísticas pobres. Essas propriedades podem levar o sistema de controle a desempenhos indesejáveis em malha fechada. Com a intenção de melhorar essas propriedades estatística, identificar um controlador simples em quantidade de parâmetros e melhorar o desempenho em malha fechada do sistema, este trabalho propõe o uso da regularização ℓ1 na formulação não linear do método VRFT. A regularização é uma técnica que tem sido amplamente empregada e pesquisada nas comunidades de Aprendizagem de Máquina e Identificação de Sistemas ultimamente. Além disso, esta técnica é apropriada para reduzir a variância das estimativas. Uma análise detalhada do efeito do ruído na estimativa é feita para o método VRFT não linear. Finalmente, três diferentes métodos de regularização, o terceiro proposto neste trabalho, são comparados com o VRFT

Modelling of thermal energy storage systems for bulk electricity storage

This report was submitted for the First Year Assessment of the PhD course in Engineering at Cambridge University Engineering Department. ABSTRACT Growing concerns about climate change and energy security are increasing worldwide efforts to decarbonize the electrical grids, pushing governments and international institutions to promote the use of Renewable Energies (RE). However, two major RE sources -wind and solar energy- present natural fluctuations, and any grid containing big portions of such sources faces the major challenge of having enough electricity storage available to match supply and demand. A new family of technologies with a high potential for large-scale electricity storage applications is emerging, which in this report are denominated Thermo-Electrical Energy Storage (TEES) systems. Generally, in a TEES system, a heat pump uses electricity to transport thermal energy from one thermal reservoir (cold) into another (hot). Energy may be stored in the form of sensible or latent heat. After storage, a heat engine is used to transform the thermal energy back into electricity. Differently from the two main competing technologies -Pumped Hydro-electric Storage (PHS) and Compressed Air Energy Storage (CAES)-, the implementation of a TEES system does not depend on specific geographical features. Additionally, it normally makes use of cheap and abundant materials and benefits from high values of energy density. The aim of this PhD project is the analysis and comparison of TEES cycles through component and cycle modelling, the identification of their main strengths and weaknesses and the suggestion of novel configurations with improved performance. The first part of this report is mainly concerned with the thermodynamic analysis of a specific TEES technology which is based on the Joule-Brayton (JB) cycle and is known as Pumped Thermal Electricity Storage (PTES). Chapter 2 reviews the fundamentals of the technology and proposes and evaluates new configurations that make use of liquid materials as storage media, substituting the solid reservoirs that have been used until now. It also presents and briefly discusses other TEES technologies that are based on variations of the Rankine cycle. The second part of this report, Chapter 3, is concerned with the modelling of specific components used in TEES cycles, such as a heat exchanger or a reciprocating compressor, and the study of packed-beds of solid particles for thermal energy storage using Computational Fluid Dynamics (CFD). Finally, a summary of the work done up-to-date and the proposed work for the continuation of the project is presented.This project was realised with the support of a graduate studentship from Peterhouse

La Auditoria Ambiental En La Proteccion Del Bien Publico Ambiental. Nexo Con La Empresa Amigable Con El Ambiente.

The environmental auditing, like appraising tool of the environmental step, part of the scientific conceived problem in: Insufficiencies in the juridical sorting of the environmental auditing in the public sector, incident in his purpose of environmental control in behalf of the friendly company with the environment and the sustainable development. You aim at argumenting the theoretic budgets of theenvironmental auditing as from his historic, doctrinal and exegetic assessment, at the end of the perfecting of his juridical sorting. The utilized methods were the juridical theoretician, the historic logician, the exegetic juridical, the by right compared, the one belonging to analysis and synthesis. As a result principal the theoretic budgets formulate perfecting of the environmental auditing in the public sector and the other forms of step in the cost-reducing social context themselves for the future. His purpose is to achieve the sustainable development with friendly companies' creation with the environment, that they enable the equilibrium between progress and the nature

Investigation of Remaining Saturation from Gas Gravity Drainage Based on Time Lapse X-Ray CT Tomography with Application in Naturally Fractured Reservoirs

Naturally fractured reservoirs (NFR) represent an important fraction of oil reserves in the world.In many of the NFR, significant volumes of oil have been or are expected to be recovered from the matrix due to the presence of the gas gravity drainage drive mechanism. Nonetheless, there are some uncertainties to accurately predict oil recovery factors and remaining fluid saturations due to this drive mechanism despite the existence of studies performed in the last three decades. Several mathematical models for gravity drainage in NFR have been developed based on results obtained from laboratory experiments. However, these models have not provided accurate results in field applications. One of the reasons is that the experiments only considered an oil-gas system which in many cases is not a realistic assumption due to the presence of connate water in the reservoirs. Another reason is that, in some cases, heterogeneities, such as vuggy porosity, were ignored in both the experiments and the mathematical models. Based on these considerations, two long-term experiments that mimicked gas gravity drainage in NFR were performed. The experiments were carried out with the purpose of acquiring data that might be used to improve current mathematical models or to develop new ones. During the experiments, time-lapse X-Ray CT images were acquired at different intervals with the objective of determining the fluids saturation along the core samples due gravity drainage. Additionally, oil produced was measured. Experiment 1 was performed in an oil-brine-air system. A stack of six Berea sandstone core samples in capillary contact was used. Initially, the stack was saturated with oil at irreducible water saturation. Experiment 2 was performed in an oil-air system. A one-piece of Edwards limestone core with primary and vuggy porosity core was used. At the initial condition, the core was saturated with oil. Due to the presence of vugs, a novel technique was developed to quantify porosity and oil saturation for the primary porous system and the vuggy porous system. For both experiments, a good match between the measured oil produced and the remaining oil volume in the matrix estimated from the remaining fluids saturations obtained through the CT X-Ray images was observed. The techniques used in these experiments provide a new, unique and reliable method to study the important phenomenon of gas gravity drainage in NFR

La construcción criminal mediática de los medios de comunicación y su incidencia en Decisiones Jurisdiccionales

La presente investigación tiene lugar la criminología mediática ya que esta está constituida por los medios de información masiva, las cuales construyen a la cuestión criminal en base a estereotipos, estigmatizaciones, causalidades mágicas; mostrando violencia y exagerando las noticias criminales, de la misma manera, utilizan un lenguaje hiperbólico, hecho que repercute en el incremento de la percepción de inseguridad y promulgación de nuevas leyes penales. Del mismo modo evidencia cómo estos medios de comunicación ejercen el control en la sociedad a través del miedo al crimen, jugando de cierta forma con la mente y la percepción de los receptores, los efectos que estos medios tienen en el subconsciente de la persona haciendo de alguna forma causar temor y miedo en la población. De esta idea partimos para resumir que la criminología se alimenta de todas las noticias, no obstante, esta se nutre primordialmente de entreteniendo banalizando los atentados y dando la idea de un mundo en conflicto. El resultado de la investigación está desarrollado mediante gráficos y cuadros, en la cual se comprobó que, los medios de comunicación si influencian en la toma de decisiones de la población, como también por medio de la presión social hacen que los magistrados y miembros del Ministerios publico tomen una decisión forzada ante una situación de presión por parte de los medios y las personas, se determinó que si hay cierto tipo de control en las noticias por parte del gobierno hacia los medios de difusión masiva estos se limitarían a difundir noticias con el fin de solo causar miedo en la población

Thermodynamic strategies for Pumped Thermal Exergy Storage (PTES) with liquid reservoirs

Pumped thermal energy storage (PTES) is a grid-scale energy management technology that stores electricity in the form of thermal energy. A number of PTES systems have been proposed using different thermodynamic cycles, including the Brayton cycle, the Rankine cycle and transcritical cycles. This talk proposes to employ the Brayton cycle together with liquid storage media (as opposed to packed beds of solid particles), and finds that employing a gas-gas regenerator is useful to adapt the cycle to the operating temperature ranges of candidate liquid materials and to improve the work ratio of the cycle. Because the cycle performance is very susceptible to heat exchanger losses, emphasis is put on employing highly-effective heat exchangers