Analysis, Design, and Optimisation of an Electromagnetic Energy Harvester

One of two major limitations of a vibration energy harvester (VEH), concerns its limited performance due to its confined physical enclosure. The maximum span realizable is attained at a specific excitation level. This excitation level provides the maximum energy harvested by the VEH device. Due to span constraints, VEHs are designed to operate at the maximum span achievable at the maximum excitation level existing within the region of interest. In this study, a constrained optimisation problem (for the VEH) is formulated and investigated. This paper focuses on the analysis, design and optimisation of a nonlinear VEH device.

Variations in seismic retrofit design of cable-stayed bridges of different sizes

<p>There are three cable-stayed bridges in Nishi-Seto Expressway, the westernmost route of Honshu- Shikoku Expressway; Shin-Onomichi Bridge (maximum span of 215 m), Ikuchi Bridge (center span of 490 m), and Tatara Bridge (center span of 890 m). The results of seismic analyses of the bridges revealed the considerable sway-mode vibrations in longitudinal direction, and seismic devices such as viscous dampers and stoppers were found to be necessary to mitigate the above vibrations. In this paper, the vibration characteristics of the cable-stayed bridges of different sizes and the difference in the seismic retrofit design for the bridges are presented.</p>

A Suggested Method for Performance Evaluation of Large Scale Fireproof Shutters

Currently, there is a limitation in the performance evaluation of a large fireproof shutter due to the constraint of the maximum size of the test equipment (3 m × 3 m). In particular, the longer the maximum span of a large fireproof shutter, the greater the fire load. Accordingly, the deformation of the large fireproof shutter is increased. The fire fragile area between the guide rails at both ends of the large fireproof shutter and the body of the fireproof shutter increases, and at the same time, the possibility of flame passing through the fragile area increases. However, the reduced-scale test is performed without reflecting the above-mentioned problems, and the maximum span of 8 m specified in KS F 4510 is widely used. Therefore, the author suggests a new method for performance evaluation of large-scale fireproof shutter, which can reflect the fire vulnerabilities of large fireproof shutter with increasing span.

Aerodynamical Optimization of Adaptable Span Wing of Telescopic Spar and Foldable Wing Tip using Computational Fluid Dynamics

The project aims to analyze aerodynamic coefficients of adaptable span wing, which increases the lift of the aircraft at various flight conditions by increasing the span of the wing and also decreases its span to adapt Group V airport gate, which is restricted to a maximum 65 m wingspan of aircraft. Present days there is no adaptable wing that changes its shape or its span. All the commercial airplane wings are only fixed wings. To increase more lift at the time of takeoff or landing, the pilot has to stay with the ailerons and flaps. But at the time of the cruise, flaps give more induced drag. Adaptable span wing paves a way to have a lift at any time with less induced drag. Airports are 6 types based on the maximum span of their gates. To increase the lift, it is easy to increase the span of a wing and to keep it fixed, but if the span is more than 65 m, it falls under the category of Group VI airports. These Group VI airports are less available, and Group V airports are mostly available worldwide. This project aims to increase the span beyond 65 m and also to accommodate in Group V airports. Methods of Telescopic spar expansion and foldable wingtip are used. For this work Boeing 777-300 ER Wing with its airfoil is taken as a reference. One side of the wing is taken for analysis, and the models have made in CATIA V5 of various length from its original half span 29.3m to 34.3m by increasing one by one metre. Also, with foldable wingtip span is increased at its unfolded state with 2m. Each and every model is analyzed with a variable angle of attack, and lift curves were obtained. These curves help us to determine the optimized span of the adaptable wing.

Fatigue Life of Reinforced Concrete Integral Bridge

Integral bridges with long spans are becoming popular day by day, as they are easy to construct with long spans and require fewer maintenance efforts due to the absence of bearings. However, due to movement restraints, fatigue stresses build-up that leads to a reduction in a useful life. In this paper results of an analytical study are presented for the fatigue life of an integral bridge exposed to transient loads. Transient analysis of reinforced concrete integral bridge of total length 156 m having 5 continuous spans with the central maximum span of 40 m has been done using ANSYS. The roles of deformation and strain that occur in the bridge have been found to influence fatigue life. Further, midpoint deflection in the longest span, its variation with loading history and its influence on fatigue life has also been analyzed and found to match satisfactorily with standard results.

Self-supporting tests in lattice joists subject to negative bending

During the construction of bridges, cantilever roofs and eaves, assembling formworks and scaffold that will support the slabs is a point of difficulty in the construction phase. Therefore, it is relevant the study of the lattice joists which serve as self-supporting formwork, supporting its weight, the weight of the fresh concrete, the weight of workers and the weight of concreting equipment. The analysis of the bearing capacity of lattice joists subject to negative bending with base concrete opening enables checking the maximum span that each lattice truss model bears, either cantilevered or between continuous spans with reduced or no scaffold. The concrete opening enables the monolithism between the slab and its support. This paper presents the results of tests on lattice joist with concrete opening. By the results analysis, formulations for designing the spacing between prop lines were found. The results are promising and indicate great possibilities of using lattice joists with concrete opening over the supports (beams), in order to optimize the slab shuttering.

Evaluación de la estabilidad de excavaciones mineras de pequeño diámetro mediante clasificaciones geomecánicas y análisis empíricos: el caso de la mina de San Juan, Ecuador

Resumen: Desde los años setenta del pasado siglo se viene empleando con éxito en todo el mundo una metodología de análisis preliminar de estabilidad de huecos subterráneos basada en el uso de las clasificaciones geomecánicas, siendo las más empleadas el RMR de Bieniawski y el índice Q de Barton. Esta última es la que se empleará en este estudio. Se trata de una aproximación empírica que permite estimar, mediante la asignación de una puntuación, la calidad del macizo rocoso, con el objetivo de conocer su grado de estabilidad ante la ejecución de una excavación subterránea. En la presente investigación se aplica el índice Q al estudio de la estabilidad de galerías y filones de una pequeña mina de oro en el Cantón de Ponce Enríquez, Ecuador. En este trabajo se propone un nuevo gráfico empírico tomando para ello otros anteriores y los resultados de la evaluación de tal manera que pueda determinarse el factor de seguridad y el máximo vano estable que pueda abrirse en minas de este tipo. Una de las principales aportaciones del trabajo es la de validar el índice de Barton a huecos pequeños.Palabras clave: Índice Q, minería artesanal, mina subterránea, máximo vano, oro.Abstract: Rock mass classifications are used throughout the world since the 1970’s. It is a methodology for the prefeasibility assessment of the stability of underground openings. The most used are the Bieniawski’s RMR and the Barton’s Q index. The latter is the one we have used in this study. It is an empirical approach that gives a numerical score to the rock mass quality to determine the degree of stability or reinforcement required. In this research, the Q index is applied to assess the stability of galleries and veins in a small gold mine in Canton Ponce Enriquez, Ecuador. A new empirical chart has been established using previous ones and considering the results of the study. This chart can be used to determine the safety factor and stable maximum span that can be opened in vein-mines of this type. One of the main contributions of the work is to validate the Barton index to small holes.Keywords: Q index, artisanal mining, underground mine, maximum span, gold.