The issue of the environment (Umwelt) often fluctuates between two extremes: the cultural environment (architecture) and the natural environment (nature). Although the idea of the "natural environment" can (paradoxically) also be understood as a cultural construct. The project explores the ambiguity of artificial vs. natural through the design of an apartment building. The proposal uses a reinforced concrete skeleton of an abandoned shopping center built at the turn of the 1970s and 1980s, into which it inserts individual "dwellings". The design examines the tools ranging from an "artificial stone" in the form of walls made of shotcrete to dramatic views of the nearby Holedná Forest, which both figuratively and literally (eg. during a walk) becomes another room of the apartments. The landscape and human emotions associated with the natural environment are an important motive for the whole proposal. To expose the tension between two modern tendencies: escape from nature vs. return to nature, it samples the topic of apartment and nature.

Este trabajo tiene como meta servir de apoyo a las siguientes generaciones de ingenieros civiles a poder analizar y diseñar torres de celosía con manuales internacionales y propios de nuestro país. Este este trabajo podrás conocer sobre el mundo de las torres eléctricas, las partes que forman, la importancia de su uso, analizar mediante el software SAP2000 y diseñar por tracción y compresión cada uno de sus elementos. / This work aims to support the next generations of civil engineers to be able to analyze and design lattice towers with international manuals and those of our country. In this work, you will be able to learn about the world of electrical towers, the parts they form, the importance of their use, analyze using the SAP2000 software and design each of its elements by traction and compression. / Tesis

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This thesis investigates the acceleration amplification experienced by solar towers mounted on the rooftops of low-rise industrial buildings during a seismic event. Specifically, this thesis looks to assess the validity of using amplification factors adopted by the ASCE 7-05Minimum Design Loads for Buildings and Other Structures to approximate seismic acceleration amplification for roof-mounted solar towers. To investigate the validity of the ASCE 7-05 amplification factors, this thesis conducts timehistory analyses of three theoretical solar towers mounted on the roof of a case study building. The time history analyses are conducted in the finite element computer modeling program SAP 2000 using 30 historical ground motion records of varying frequency content. Based on the results of the time history analyses, modifications to the ASCE 7-05 provision specific to roof-mounted solar towers are proposed.

"Between the Ocean and the Bay" is about a design process enabling the designer to see and know through three different graphic methods. The thesis concentrates both on the design of a specific structure, and on the ability to develop a design through two and three dimensional graphic manipulations. The three design methods are sketching, three-dimensional modeling, and computer drawing. All three have their unique qualities and all are effective. The Sketching method evolved through observing, seeing and drawing architecture in western Europe. The intimate visual process formulated a greater sense and comprehension of architecture. The on site drawing experience initiated this particular design expression. Furthermore the fragments of architecture recorded in these visual sketches became a vocabulary for all future designs. There are two kinds of three dimensional models. The first is for displaying a building or a project as an object in three dimensions. The second is a sketch, which is a fragment of a whole building or an idea. Fragmentary modeling provides a simple method of combining three dimensional elements enabling one to scrutinize them as they become part of a whole composition. This method of modeling allows the observer to see the spatial relationships between each element and the form as a whole. Modeling is a tactile experience. This physical involvement brings to the design a tangible relationship that develops scale and proportion. Fragment modeling was used in the development of the house between the ocean and the bay. Computer drawing produces two dimensional drafted plans or wire frame models that are viewed from infinite angles and then reproduced. Computer drafting lacks immediate tactile involvement of the other two methods of design discussed here. The results can appear to be flat and not dynamic. However, the computer provides discipline; by forcing one to make decisions on a design, it organizes abstract visual thoughts. There was a point in the designing of the house when turning to the computer to explore order was essential. The house between the ocean and the bay developed by employing the three different yet complementary design tools. Sketching was the strongest tool to explore a design problem through quick immediate production. Modeling forced the realization in space of the strengths and weaknesses of a design. The computer drawings in this project helped control the final shape of the house simply by forcing decisions and creating order. Each of these methods is productive by itself and together as they meld and feed on each other to create the product. / Master of Architecture

The use of <i>Casuarina equisetifolia</i> trees grown in Senegal as utility poles was investigated as follows: (1) to determine the longitudinal air permeability of the species with regard to its treatability; (2) to determine the treatability of the wood using a full-cell process; (3) to determine the mechanical properties of the species relative to its use as utility poles in Senegal. The mean superficial longitudinal air permeability of 60 specimens was 4990 cm³(air)/cm s atm whereas the theoretical permeability was 4710 cm³/cm s atm. It was determined an average of 1830 vessels per cm² with a mean diameter of 117 microns and a volume fraction of 0.20 . The presence of tyloses was not observed during the anatomical measurements. As expected, the most important variables influencing the effectiveness of the preservative treatment were the impregnation pressure and the permeability of the specimens. Retention increased as the impregnation pressure was increased; and at a given pressure, retention was positively correlated to permeability. Since the wood seems to be fairly permeable, it can therefore be satisfactorily treated by controlling the impregnation pressure. The results of static bending tests were compared to the theoretical maximum stress at ground line (R) of the different classes of utility poles used in Senegal. With an average modulus of rupture (MOR) of 108 megaPascals, the ratio of MOR to R varied between 2.12 to 2.34. This ratio provides evidence that Casuarina's wood meets the mechanical requirements of the Standard NFC67-100, which sets the guidelines for utility poles in Senegal. / Master of Science

Neste trabalho foi realizada a modelagem fenomenológica do desempenho de uma torre de resfriamento de água e de um sistema de duas torres de resfriamento em série, com temperatura de água de entrada de até 65 ºC. Verificou-se a validade do modelo através de comparação dos resultados previstos com os obtidos em ensaios em uma unidade piloto. Em seguida, através de simulação matemática, a partir do modelo desenvolvido, foi feito o estudo de diversos casos de aplicação. Estudou-se a influência das principais variáveis de operação (vazão de ar, vazão de água e temperatura de bulbo úmido) no desempenho de torres de resfriamento acopladas (em série e em paralelo) e no custo operacional. Verifica-se que a variável de maior influência é a vazão de água que circula pela torre. / This is a study about the phenomenological modeling of the performance of a water cooling tower and a system of two cooling towers in series, with water temperature input up to 65°C. The validity of model was verified by comparing the expected results with those obtained in tests on a pilot plant. After this, through a mathematical simulation, based on the model developed, several cases of application were analyzed. It was studied the influence of main operating variables (air flow, water flow and wet bulb temperature) on the performance of couples cooling towers (in series and parallel) and on operational cost. It was verified the most influential variable is the water flow rate through the tower.

Neste trabalho foi realizada a modelagem fenomenológica do desempenho de uma torre de resfriamento de água e de um sistema de duas torres de resfriamento em série, com temperatura de água de entrada de até 65 ºC. Verificou-se a validade do modelo através de comparação dos resultados previstos com os obtidos em ensaios em uma unidade piloto. Em seguida, através de simulação matemática, a partir do modelo desenvolvido, foi feito o estudo de diversos casos de aplicação. Estudou-se a influência das principais variáveis de operação (vazão de ar, vazão de água e temperatura de bulbo úmido) no desempenho de torres de resfriamento acopladas (em série e em paralelo) e no custo operacional. Verifica-se que a variável de maior influência é a vazão de água que circula pela torre. / This is a study about the phenomenological modeling of the performance of a water cooling tower and a system of two cooling towers in series, with water temperature input up to 65°C. The validity of model was verified by comparing the expected results with those obtained in tests on a pilot plant. After this, through a mathematical simulation, based on the model developed, several cases of application were analyzed. It was studied the influence of main operating variables (air flow, water flow and wet bulb temperature) on the performance of couples cooling towers (in series and parallel) and on operational cost. It was verified the most influential variable is the water flow rate through the tower.

Electromagnetic effects of lightning currents during a direct hit to tall communication towers, other instrumented towers and chimneys can be hazardous to associated cables, as well as, electrical and electronics systems. The standard practice in telecommunication and other related fields is to bond the cable sheath to the tower and ground connection is made before it enters the base station. However, in some specific cases when power, signal and data logging cables are to be supported on the same tower, isolation of power cables is demanded. In a totally different situation, attempts are also made to have a dedicated isolated down conductor. A critical review of the situation demanded a more quantitative answer to the following questions: (i) whether it is possible to electrically isolate a dedicated down conductor, (ii) is it possible to electrically isolate the cables and their terminal equipment both mounted on towers serving as down conductor and if so, what will be the nature of current induced in the cables and (iii) as per the standard practice, if the cable sheaths are connected to the tower/structure, what will be the nature of the current shared by them. Addressing these important issues formed the scope of the present work. For the tall structures considered in this work, for the critical time periods, wave nature of the current dominates. This called for electromagnetic modeling covering Transverse Magnetic (TM) mode of the wave propagation. Owing to the complex geometrical features involved with the problem, both experiments on electromagnetically scaled laboratory models, as well as, theoretical simulation is attempted. An electromagnetically scaled laboratory model is employed for the time domain experimental investigation. This approach, which has been validated earlier, is further scrutinized to ensure its adequacy. In order to achieve generality and noting the fact that the associated parameters are rather difficult to be varied in the experimentation, theoretical investigation is also employed. For this, both NEC-2, as well as, an in-house thin wire time domain code developed for this work is employed. NEC-2 could handle multi-wire multi-radius junctions, while in-house time domain code could handle proximity and non-cylindrical shapes encountered with tower lattice elements. The investigation of induction to isolated cables on simple down conductors and towers is considered first. The induced current is shown to be bipolar oscillatory with the period of oscillation governed by the length of the cable. It is shown that the level of induction for good earth termination is below 5 – 10 % while that with moderate inductance in the earth termination can enhance the induction to higher levels. The level of induction is shown to be not critically dependent on the length of the cable, gap between cable and down conductor/tower. When multiple cables are mounted, they seem to influence each other and individually carry currents of lower amplitude. Also, the effect of shape and proximity of the tower lattice elements on induction is investigated. If the cable is housed inside a metallic tray, the amplitude of induced current is shown to be quite small. Subsequently, the evaluation of electrical stress between the isolated down conductor on tower and simplified representation of the structure is considered. A suitable definition of the electric stress for the wave regime is evolved and then it is shown that, at present, the voltage difference defined by the path integral of electric field across shortest path between the two entities is the best indicator for the stress. The electrical stress in the case of isolated down conductor on tower, as well as, down conductor with isolated cable is shown to reach very dangerous levels. On the other hand, the stress on the isolated cables on towers also serving as down conductors is shown to be relatively moderate. Interestingly, it is shown that the electrical stress and the voltage difference is dependent on the gap and for the critical time period, can be much lower than that calculated as a product of equivalent tower surge impedance and the stroke current, even before the arrival of ground end reflections. Finally, the current shared by cables connected to the down conductor is investigated. For the case of simple cylindrical down conductor with cable connected to it at the top, it is shown that the amount of current shared by the cable is not dependent on its length and the relative radii (cross section) have only a weak influence. For the case with down conductor formed by L and + angles, it is shown that the placement of cable at their interior corner can reduce the initial current shared by the cable. In order to model best possible situation with towers, experiments are conducted with cable inside an aluminum pipe. Even in this case, cable current builds up with successive reflections to become comparable with the current through the pipe itself. Subsequent investigation with 1:40 and 1:20 tower models lead to several interesting observations. Cables running along leg/face of the tower whether placed inside or outside the tower, always shares good amount of current. Further, frequent bonding of the sheath to the tower increases the current shared by the cable. Cable when housed in a metallic tray shares less than 50% of the current shared without the tray. Even though a complete quantification is not to be achieved in this work, it has made a good beginning with some significant contribution towards lightning protection issues pertaining to tall towers and structures.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / Cooling tower rain zone performance characteristics such as the loss coefficient and the Merkel number are evaluated and simulated. To this end the influence of drop diameter and drop deformation on the velocity, path length and cooling of single water drops are investigated. Experimental drop size and pressure drop data over a counterflow rain zone are presented and the effect of drop deformation on the pressure drop is investigated using the experimental data and CFD. Using the experimental drop size data and CFD, the performance uncertainty produced by using the Rosin-Rammler drop distribution function as opposed to the discrete drop distribution data is investigated. CFD models are developed to investigate the feasibility of modelling rain zones by assuming a constant drop diameter and to establish which diameter definition is the most representative of a particular polydisperse drop distribution. These models were used to validate the correlations for the rain zone performance characteristics proposed in literature.