RESUMEN Este artículo describe un método analítico para el análisis de elementos viga-columna con condiciones de borde generalizadas apoyadas en una fundación elástica Pasternak homogénea o no-homogénea. La formulación matemática utilizada en este documento es una presentada recientemente por el autor principal. La ecuación diferencial (ED) que gobierna el comportamiento del elemento viga-columna se resuelve utilizando el método de transformación diferencial (DTM). Para el modelo estructural propuesto, el DTM ofrece ventajas prácticas sobre otros métodos. La formulación propuesta proporciona la flexibilidad de tener en cuenta i) carga lateral y axial combinada en los extremos del elemento, ii) suelo homogéneo o no-homogéneo, iii) fundación elástica Pasternak, y iv) una carga transversal arbitraria externa que actúa a lo largo del elemento. Los efectos de varias relaciones de esbeltez, relaciones de rigidez y condiciones de borde clásicas e intermedias se pueden estudiar fácilmente con la formulación propuesta. Se presentan ejemplos para validar la precisión del modelo y su aplicabilidad en una amplia gama de análisis.

ABSTRACT This paper describes an analytical approach to conduct an analysis of beam-column elements with generalized end-boundary conditions on a homogeneous or non-homogeneous Pasternak elastic foundation. The mathematical formulation utilized herein is that presented by the senior author in a recent work. The differential equation (DE) governing the behavior of the beam-column element is solved using the differential transformation method (DTM). The DTM offers practical advantages over other conventional approaches when solving the proposed structural model. The proposed formulation provides the flexibility to account for i) combined lateral and axial load at the ends of the element, ii) homogeneous or non-homogeneous soil, iii) Pasternak elastic foundation, and iv) an external arbitrary transverse load acting on the element. The effects of various slenderness ratios, pile-soil stiffness ratios, and classical and semirigid boundary conditions can be easily studied with the proposed formulation. Examples are presented to validate the accuracy of the model and its applicability over a wide range of analyses.

Abstract: Aiming to provide greater visibility for the wood species Acrocarpus fraxinifolius, the present study sought to analyze the influence of heat treatment on an industrial scale applied to wood species, also popularly known as Indian cedar. The heat treatment was carried out in an autoclave, with temperature and pressure control, and with saturated steam injection, for temperatures 155 ºC, 165 ºC, 175 ºC, and 185 ºC. Physical, chemical, and mechanical tests were carried out for the analyzed wood. The content of holocellulose and total lignin decreased, while the content of extractives showed a substantial increase. The density increased after the heat treatment, however the treated wood showed cracks, and these cracks influenced the significant loss of the values of the mechanical properties of compression, tension, and flexion. The shear showed strength gain for the temperature of 155 ºC, and the wood treated at 165 ºC was equivalent to untreated wood. The woods submitted to temperatures of 175 ºC and 185 ºC presented strength losses. The heat treatment in question contributes to increase the visibility, use and market value of wood.

Abstract: Indian cedar (Acrocarpus fraxinifolius) is a wood species that occurs naturally in India, Myanmar (Burma) and Bangladesh, and has a high commercial value, with characteristics like mahogany and native cedars. The planting of Indian cedar has been undertaken in Brazil, but there is little information available regarding the characterization of the species. Therefore, considering its timber potential and its possibility of development in the country, the present work aimed to evaluate the physical, chemical, and mechanical properties of 9-year-old Indian cedar wood, planted in the southern region of Brazil. A low specific mass (502 kg/m³), low average dimensional stability (anisotropy coefficient of 2,09 %) was observed, in addition to the low content of extractives (1,94 %). From the mechanical characterization, an average value for the elastic modulus of 8963 MPa was obtained, and for the compressive strength parallel to the grain the average and characteristic values were 32,14 MPa and 21,46 MPa, respectively. This indicates that this wood belongs to resistance class C20 (dicotyledons). The results obtained classify the wood for use in light, external, or internal civil construction.

ABSTRACT The effect of AOA (anaerobic, aerobic, anoxic) sequence was studied in the operation of a modified sequential batch reactor, at laboratory scale, under conditions of suspended and attached biological growth SAG-SBR, in order to verify the simultaneous removal of organic matter and nutrients (nitrogen and phosphorus). An acrylic reactor was used with a useful volume of 10,2 liters, that integrated a stirrer, internal recirculation and aeration system; synthetic sewage (SW) was used for simulating a domestic wastewater of medium concentration and the means of contact were spheres and concentric cylinders of polypropylene. During the research, the AOA sequence was used with different cycles and duration times (A = 15.5 h, B = 13 h; C = 11.5 h, D = 9.5 h) applying at the end the sedimentation of mixture liquor. An accurate monitoring of the most important parameters of control process such as dissolved oxygen (DO), pH, temperature and potential oxidation reduction was made and significant results were obtained in the analyzed physicochemical parameters as chemical demand oxygen (CDO), nitrogen and phosphorus, particularly with greater efficiency in lower hydraulic retention time. It is like that removals were achieved in MO the order of 97%; 71% nitrogen and 40% phosphorus. The cycle with the best performing was D, with a total time of 9.5 hours and a removal of 96.6% of MO; 70% N and 51.2% P.

RESUMEN Se estudió el efecto de la secuencia anaeróbica, óxica, anóxica (AOA) en el funcionamiento de un reactor secuencial por tandas modificado a escala laboratorio, bajo condiciones de crecimiento biológico suspendido y adherido SAG-SBR (Suspended and Attached Growth Sequencing Batch Reactor), con el propósito de verificar la remoción simultánea de materia orgánica (MO) y de nutrientes (nitrógeno y fósforo). Se empleó un reactor de acrílico con un volumen útil de 10,2 litros, que integró un sistema de agitación, recirculación interna y aireación; se utilizó agua residual sintética (ARS), simulando un agua residual doméstica de concentración media y como medio de contacto se emplearon esferas y cilindros concéntricos de polipropileno. Durante la investigación, se empleó la secuencia AOA con diferentes ciclos y tiempos de duración (A=15,5 h; B=13 h; C=11,5 h, D= 9,5 h), aplicando al final la sedimentación del licor mezcla. Se realizó un estricto seguimiento de los parámetros de control más importantes del proceso como oxígeno disuelto (OD), pH, temperatura y potencial de óxido reducción (ORP, por sus siglas en inglés) y se obtuvieron resultados significativos de remociones de los parámetros fisicoquímicos analizados, como demanda química de oxígeno (DQO), nitrógeno y fósforo, en particular con mayor eficiencia en las corridas efectuadas con los ciclos de menor tiempo de retención hidráulica. Es así, como se lograron eliminaciones en MO del orden del 97%; en nitrógeno del 71% y en fósforo del 40%. El ciclo con mejores resultados fue el ciclo D, con un tiempo total de 9,5 horas de duración y con una eliminación de MO del 96,6%; en N del 70% y en P del 51,2%.

No Estado de São Paulo, principalmente em áreas rurais, é notável a utilização de postes roliços de madeira para diversas finalidades. Neste contexto, observa-se que a madeira, em contato com o solo, deteriora-se mais rapidamente, e essa deterioração está geralmente associada aos fatores ambientais e, principalmente, à presença de insetos e fungos. Com o auxílio de modelos matemáticos, pode ser prevista a vida útil das estruturas de madeira pela obtenção de "índices climáticos", que indicam comparativamente, entre as regiões estudadas, quais possuem maiores e menores propensões ao ataque de fungos e insetos. Neste trabalho, utilizando dados climatológicos de várias cidades do Estado de São Paulo, foi obtido um modelo matemático simplificado de agressividade à madeira em contato com o solo.

In São Paulo State, mainly in rural areas, the utilization of wooden poles is observed for different purposes. In this context, wood in contact with the ground presents faster deterioration, which is generally associated to environmental factors and, especially to the presence of fungi and insects. With the use of mathematical models, the useful life of wooden structures can be predicted by obtaining "climatic indexes" to indicate, comparatively among the areas studied, which have more or less tendency to fungi and insects attacks. In this work, by using climatological data of several cities at São Paulo State, a simplified mathematical model was obtained to measure the aggressiveness of the wood in contact with the soil.