Covariance properties and regularization of conserved currents in tetrad gravity

We discuss the properties of the gravitational energy-momentum 3-form within the tetrad formulation of general relativity theory. We derive the covariance properties of the quantities describing the energy-momentum content under Lorentz transformations of the tetrad. As an application, we consider the computation of the total energy (mass) of some exact solutions of Einstein's general relativity theory which describe compact sources with asymptotically flat spacetime geometry. As it is known, depending on the choice of tetrad frame, the formal total integral for such configurations may diverge. We propose a natural regularization method which yields finite values for the total energy-momentum of the system and demonstrate how it works on a number of explicit examples.

Path integral approach to the full Dicke model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise histomorfométrica do processo de reparo após o reimplante de dentes de rato mantidos em soro do leite bovino e leite integral

Pós-graduação em Odontologia - FOA

On volterra integral equations on time scales

The purpose of the present paper is to study some properties of solutions of Volterra integral equations on time scales. We generalize to a time scale some known properties concerning continuity and convergence of solutions from the continuous case.

Introdução a noções de cálculo diferencial e integral no ensino médio no contexto das TIC: implicações para prática do professor que ensina matemática

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação microscópica da propriedade biológica e da biocompatibilidade do osso composto e do osso integral de origem bovina

The aim of this study was to evaluate the biological properties and biocompatibility of bovine non-demineralized lyophilized and composite bones implanted in tibiae bone cavities and at the subcutaneous level. Twenty-four rats were used and sacrificed 15 and 45 days later. At the subcutaneous level, after 15 days an inflammatory reaction was seen around biomaterial particles with the presence of giant cells and at 45 days fibrous connective tissue had also developed. No signs of ectopic bone formation were observed at tibiae regions; more bone neoformation was observed at the control group (15 days) with 42.8% of the outer cortex layer against 22.6% at Orthogen and 25% at GenMix groups. At 45 days, correspondent values for bone neoformation were 62.5% at control, 26% at Orthogen, and 35% at GenMix groups, respectively. It can be concluded that both materials tested were biocompatible aiming to bone neoformation by their osteoconductive properties with no ectopic formation sites observed.

Suco integral de amora (Morus nigra L.) obtido através de prensagem e despolpamento: rendimento e caracterização físico-química

Mulberry (Morus nigra L.) is a fruit with a great potential for technological uses, which could be employed to manufacture of syrups, ice cream, candies, yoghurts, beverages, jam, etc. Only the leaf from mulberry trees is commercially used for silkworm feeding. This tree is cultivated on many agricultural environments such as small rural proprieties and settlements. Small farmers waste a great amount of their production for not knowing about mulberry technology. Thus, the objective of this work was to access extraction yield and physical-chemical properties of mulberry whole juice from ripe, green and a mixture of both by using press and depulper. Statistical analysis of results was carried by media and standard deviation calculations. 173 kg of mulberry were picked being 49.31% ripe and 50.68% green. Press delivered greater extraction yield of whole juice (80.50% to 81.60%) when compared to press (71.43% to 77.50%). Whole juice obtained from both equipments has shown the following values: soluble solids 7.45% - 12.11%, titrable acidity 0.45 – 1.23%, ratio 6.03 – 26.84, pH 3.69 – 4.35, total reducing sugar 4.05% – 9.96%, reducing sugar 3.95% - 9.15%, sucrose 0.00% - 0.04%, turbidity 221.25 NTU - >4,000 NTU. Whole juices obtained from both equipments has shown similar physical-chemical characteristics except turbidity. The authors concluded that press was the best extraction equipment due to its greater yield and whole juice quality regarding turbidity

Integral form of Yang-Mills equations and its gauge invariant conserved charges

Despite the fact that the integral form of the equations of classical electrodynamics is well known, the same is not true for non-Abelian gauge theories. The aim of the present paper is threefold. First, we present the integral form of the classical Yang-Mills equations in the presence of sources and then use it to solve the long-standing problem of constructing conserved charges, for any field configuration, which are invariant under general gauge transformations and not only under transformations that go to a constant at spatial infinity. The construction is based on concepts in loop spaces and on a generalization of the non-Abelian Stokes theorem for two-form connections. The third goal of the paper is to present the integral form of the self-dual Yang-Mills equations and calculate the conserved charges associated with them. The charges are explicitly evaluated for the cases of monopoles, dyons, instantons and merons, and we show that in many cases those charges must be quantized. Our results are important in the understanding of global properties of non-Abelian gauge theories.

Laser shock peening without absorbent coating (LSPwC) effect on 3D surface topography and mechanical properties of 6082-T651 Al alloy

The influence of nanosecond laser pulses applied by laser shock peening without absorbent coating (LSPwC) with a Q-switched Nd:YAG laser operating at a wavelength of λ = 1064 nm on 6082-T651 Al alloy has been investigated. The first portion of the present study assesses laser shock peening effect at two pulse densities on three-dimensional (3D) surface topography characteristics. In the second part of the study, the peening effect on surface texture orientation and micro-structure modification, i.e. the effect of surface craters due to plasma and shock waves, were investigated in both longitudinal (L) and transverse (T) directions of the laser-beam movement. In the final portion of the study, the changes of mechanical properties were evaluated with a residual stress profile and Vickers micro-hardness through depth variation in the near surface layer, whereas factorial design with a response surface methodology (RSM) was applied. The surface topographic and micro-structural effect of laser shock peening were characterised with optical microscopy, InfiniteFocus® microscopy and scanning electron microscopy (SEM). Residual stress evaluation based on a hole-drilling integral method confirmed higher compression at the near surface layer (33 μm) in the transverse direction (σmin) of laser-beam movement, i.e. − 407 ± 81 MPa and − 346 ± 124 MPa, after 900 and 2500 pulses/cm2, respectively. Moreover, RSM analysis of micro-hardness through depth distribution confirmed an increase at both pulse densities, whereas LSPwC-generated shock waves showed the impact effect of up to 800 μm below the surface. Furthermore, ANOVA results confirmed the insignificant influence of LSPwC treatment direction on micro-hardness distribution indicating essentially homogeneous conditions, in both L and T directions.

Mechanical properties enhancement of high reliability metallic materials by laser shock processing

Laser shock processing (LSP) is being increasingly applied as an effective technology for the improvement of metallic materials surface properties in different types of components as a means of enhancement of their corrosion and fatigue life behavior. As reported in previous contributions by the authors, a main effect resulting from the application of the LSP technique consists on the generation of relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Additional results accomplished by the authors in the line of practical development of the LSP technique at an experimental level (aiming its integral assessment from an interrelated theoretical and experimental point of view) are presented in this paper. Concretely, follow-on experimental results on the residual stress profiles and associated surface properties modification successfully reached in typical materials (especially Al and Ti alloys) under different LSP irradiation conditions are presented along with a practical correlated analysis on the protective character of the residual stress profiles obtained under different irradiation strategies and the evaluation of the corresponding induced properties as material specific volume reduction at the surface, microhardness and wear resistance. Additional remarks on the improved character of the LSP technique over the traditional “shot peening” technique in what concerns depth of induced compressive residual stresses fields are also made through the paper.

Impedance of foundations using the Boundary Integral Equation Method

Dynamic soil-structure interaction has been for a long time one of the most fascinating areas for the engineering profession. The building of large alternating machines and their effects on surrounding structures as well as on their own functional behavior, provided the initial impetus; a large amount of experimental research was done,and the results of the Russian and German groups were especially worthwhile. Analytical results by Reissner and Sehkter were reexamined by Quinlan, Sung, et. al., and finally Veletsos presented the first set of reliable results. Since then, the modeling of the homogeneous, elastic halfspace as a equivalent set of springs and dashpots has become an everyday tool in soil engineering practice, especially after the appearance of the fast Fourier transportation algorithm, which makes possible the treatment of the frequency-dependent characteristics of the equivalent elements in a unified fashion with the general method of analysis of the structure. Extensions to the viscoelastic case, as well as to embedded foundations and complicated geometries, have been presented by various authors. In general, they used the finite element method with the well known problems of geometric truncations and the subsequent use of absorbing boundaries. The properties of boundary integral equation methods are, in our opinion, specially well suited to this problem, and several of the previous results have confirmed our opinion. In what follows we present the general features related to steady-state elastodynamics and a series of results showing the splendid results that the BIEM provided. Especially interesting are the outputs obtained through the use of the so-called singular elements, whose description is incorporated at the end of the paper. The reduction in time spent by the computer and the small number of elements needed to simulate realistically the global properties of the halfspace make this procedure one of the most interesting applications of the BIEM.

Effect of Thermal Treatments on the Mechanical Properties Enhancement of High Reliability Metallic Materials by Laser Shock Processing

Laser shock processing (LSP) is increasingly applied as an effective technology for the improvement of metallic materials mechanical properties in different types of components as a means of enhancement of their fatigue life behavior. As reported in previous contributions by the authors, a main effect resulting from the application of the LSP technique consists on the generation of relatively deep compression residual stresses fields into metallic components allowing an improved mechanical behaviour, explicitly the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Additional results accomplished by the authors in the line of practical development of the LSP technique at an experimental level (aiming its integral assessment from an interrelated theoretical and experimental point of view) are presented in this paper. Concretely, experimental results on the residual stress profiles and associated mechanical properties modification successfully reached in typical materials under different LSP irradiation conditions are presented. In this case, the specific behavior of a widely used material in high reliability components (especially in nuclear and biomedical applications) as AISI 316L is analyzed, the effect of possible “in-service” thermal conditions on the relaxation of the LSP effects being specifically characterized. I.

Integral energy performance characterization of semi-transparent photovoltaic elements for building integration under real operation conditions

In this paper, a methodology for the integral energy performance characterization (thermal, daylighting and electrical behavior) of semi-transparent photovoltaic modules (STPV) under real operation conditions is presented. An outdoor testing facility to analyze simultaneously thermal, luminous and electrical performance of the devices has been designed, constructed and validated. The system, composed of three independent measurement subsystems, has been operated in Madrid with four prototypes of a-Si STPV modules, each one corresponding to a specific degree of transparency. The extensive experimental campaign, continued for a whole year rotating the modules under test, has validated the reliability of the testing facility under varying environmental conditions. The thermal analyses show that both the solar protection and insulating properties of the laminated prototypes are lower than those achieved by a reference glazing whose characteristics are in accordance with the Spanish Technical Building Code. Daylighting analysis shows that STPV elements have an important lighting energy saving potential that could be exploited through their integration with strategies focused to reduce illuminance values in sunny conditions. Finally, the electrical tests show that the degree of transparency is not the most determining factor that affects the conversion efficiency.

Effect of Thermal Treatments on the Mechanical Properties Enhancement of High Reliability Metallic Materials by Laser Shock Processing

Laser shock processing (LSP) is increasingly applied as an effective technology for the improvement of metallic materials mechanical properties in different types of components as a means of enhancement of their fatigue life behavior. As reported in previous contributions by the authors, a main effect resulting from the application of the LSP technique consists on the generation of relatively deep compression residual stresses fields into metallic components allowing an improved mechanical behaviour, explicitly the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Additional results accomplished by the authors in the line of practical development of the LSP technique at an experimental level (aiming its integral assessment from an interrelated theoretical and experimental point of view)are presented in this paper. Concretely, experimental results on the residual stress profiles and associated mechanical properties modification successfully reached in typical materials under different LSP irradiation conditions are presented. In this case, the specific behavior of a widely used material in high reliability components (especially in nuclear and biomedical applications) as AISI 316L is analyzed, the effect of possible “in-service” thermal conditions on the relaxation of the LSP effects being specifically characterized.

Acústica de las iglesias jesuíticas como parte del patrimonio integral en Córdoba y San Ignacio Miní

En esta investigación se aborda el tema del comportamiento acústico de las Iglesias Jesuíticas de la ciudad de Córdoba (Argentina) y San Ignacio Mini ubicada en la localidad de San Ignacio, provincia de Misiones (Argentina), construidas hace dos siglos atrás y declaradas Patrimonio de la Humanidad, con el objetivo de evaluar los parámetros que determinan la comprensión de la palabra y la aptitud de cada una de las iglesias para el canto y la música religiosa. En una primera etapa la investigación se orientó a profundizar en las características constructivas interiores de cada templo y a proponer una metodología de análisis para comparar los resultados de las mediciones objetivas, realizadas mediante la implementación de mediciones in situ, con los resultados de las apreciaciones subjetivas resultantes de la elaboración de encuestas, a los fines de caracterizar acústicamente cada espacio sonoro. Se seleccionaron, para la caracterización objetiva de cada templo, aquellos parámetros que permiten sintetizar las propiedades acústicas relacionadas con la música y la palabra, y aquellos que posibilitan medir la proporción efectiva de las primeras reflexiones, consideradas como índices subjetivos de la capacidad de distinción del sonido por parte del oyente. Se comparan los valores alcanzados con las preferencias subjetivas obtenidas en las encuestas de opinión. Se relevaron tiempos de reverberación altos en todas iglesias, fuera de los considerados óptimos para cada recinto. Se analizaron los índices de calidad y se comprobó cómo influyen los diferentes materiales en el comportamiento acústico de cada recinto. Para la evaluación subjetiva se implementó una encuesta ya validada en la que se privilegió la fácil asociación entre parámetros acústicos y psicoacústicos, esto posibilitó encontrar aquellos parámetros objetivos, simulados con público, que estuviesen fuertemente relacionados con el juicio subjetivo, así como aquellos con menor correlación. La búsqueda y relevamiento de material grafico, fotográfico y otros documentos históricos posibilitó la reconstrucción de cada iglesia para su modelización y la evaluación del comportamiento de todos los templos con la presencia de feligreses, no habiéndose podido realizar mediciones bajo esta condición. El interés por obtener datos acústicos más precisos de la Iglesia San Ignacio Mini, que actualmente se encuentra en ruinas, llevó a utilizar herramientas más poderosas de cálculo como el método de las fuentes de imagen “Ray Tracing Impact” por medio del cual se logró la auralización. Para ello se trabajó con un archivo de audio que representó la voz masculina de un sacerdote en el idioma jesuítico-guaraní, recuperando así el patrimonio cultural intangible. ABSTRACT This research addresses the acoustic behavior of the Jesuit Churches in Cordoba City (Argentina) and San Ignacio Mini (located in the town of San Ignacio, Misiones, Argentina), built two centuries ago and declared World Heritage Sites, with the objective to evaluate the parameters that determine the speech comprehension and the ability of each of the churches for singing of religious music. The first step of the work was aimed to further investigate the internal structural characteristics of each temple and to propose an analysis methodology to compare the objective results of in situ measurements with the subjective results of surveys, in order to characterize acoustically each sound-space. For the subjective characterization of each temple, those parameters that allow synthesizing the acoustic properties related to music & speech and measuring the subjective indices for the recognition of sounds, were selected. Also, the values were compared with the ones obtained from the surveys. High reverberation times were found in all churches, which is not considered optimal for the enclosed areas of the temples. The quality indices were analyzed and it was found how the different materials influence in the acoustic behavior of each enclosure. For subjective evaluation, a survey was implemented (that was previously validated) where the association between acoustic and psychoacoustic parameters was privileged; this allowed to find those objective parameters who were strongly related to the subjective ones, as well as those with lower correlation. Photographic and graphic material and other historical documents allowed the reconstruction of each church for its modeling, and also the evaluation of the performance of all the temples in the presence of their congregation. The interest in obtaining more accurate acoustic data of the San Ignacio Mini Church, which is now in ruins, led to the use of most powerful methods, as for example the image-sources "Ray Tracing Impact" method. For this, an audio archive was used, representing a male voice of a priest in the Jesuit-Guaraní language; recovering in this way intangible cultural heritage.