417 research outputs found
Meat yield of Bolinus brandaris (Gastropoda: Muricidae): comparative assessment of the influence of sex, size and reproductive status
The present study assessed the influence of sex, size and reproductive status on the meat yield (soft tissues proportion) of the purple dye murex (Bolinus brandaris) from the Ria Formosa lagoon (southern Portugal). During one year of monthly sampling (October 2008-September 2009), average meat yield of B. brandaris was 40.5 +/- 6.1% (range: 25.8-56.1% wet weight), with no significant differences between sexes. Relationships established between specimen size and soft parts weight indicated that both shell length and total weight are excellent indicators of meat yield. Significant differences in meat yield between size classes further reinforced the trend of increasing meat yield during ontogeny. Meat yield exhibited significant monthly variation and a similar temporal trend in both sexes, which were directly related to the reproductive status. Meat yield of B. brandaris was compared with that of other muricid species and the marked influence of the reproductive status on meat yield prompted a comparative assessment of the spawning season and peak of three sympatric muricids (B. brandaris, Hexaplex trunculus and Stramonita haemastoma). Overall, these findings have implications at diverse levels, including the management, regulation and inspection of this fishing/ harvesting activity and the commercialization and consumption of this seafood product.postdoctoral grant [SFRH/BPD/26348/2006]; Fundacao para a Ciencia e Tecnologia (FCT - Portugal); Fisheries Operational Programme (PROMAR); European Fisheries Fund [EFF 2007-2013]info:eu-repo/semantics/publishedVersio
Warehouse Storing and Collecting of Parts
This report deals with reducing the high costs resulting from the wear and tear of the fork-lifts used to store or collect items in a warehouse. Two problems were identified and addressed separately. One concerns the way items should be stored or collected at storage locations on the shelves of one corridor. The other problem seeks for an efficient way to define which fork-lift should operate on each corridor, and the order by which the fork-lifts should visit the corridors.
We give to both problems formulations that fit in the framework of combinatorial optimization
The design and performance of high-performance perforated fired masonry bricks
Fire perforated clay masonry units have been extensively used through years in masonry structures,
particularly in masonry walls both for loadbearing and non-loadbearing purposes (partition walls and
enclosures). The location of the masonry walls as external enclosure brings some physical
requirements, which together with mechanical requirements are the basis of the design of hollow clay
bricks.
This chapter provides an overview of the design requirements and design concepts of hollow clay
bricks, together with some recent trends arising in the framework of obtaining more sustainable
constructive materials. It discusses the main issues related to the mechanical performance of the units
and of the masonry assemblages under distinct loading conditions. As often the unreinforced hollow
clay masonry is built in seismic prone regions, an emphasis is given to the seismic behavior of hollow
clay brick masonry under combined vertical and lateral in-plane loading, being discussed the main
seismic performance parameters
Evaluation of the in-plane seismic performance of stone masonry walls
Although traditional historic masonry walls can be viewed as unsuitable structures to undergo seismic actions, they, in fact, exist and frequently represent the major structural elements of ancient buildings. Brick unreinforced masonry walls have been widely studied both from experimental and numerical point of view, but scarce experimental information is available for stone masonry walls. Therefore, the present work aims at increasing the insight about the behavior of typical ancient masonry walls under cyclic loading. Besides the strength and stiffness characterization, information about nonlinear deformation capacity is provided in terms of ductility factor and lateral drifts, which represent a step forward for the new concepts of performance based design
Assessment of the in-plane shear strength of stone masonry walls by simplified models
The present work intends to represent a further step in the knowledge of ancient
stone masonry walls through an experimental approach, from which only few information is
available. The main results of an experimental program based on in-plane static cyclic tests
conduct on masonry wall panels with distinct masonry bond are presented. It is also revealed
that simplified models, often used to predict the lateral shear strength of brick masonry walls
submitted to static in-plane lateral loading, are also valid for stone masonry walls. Besides, the
prediction of the lateral strength by means of a novel equilibrium model is also pointed out
Modern masonry structures and earthquakes : reinforced or unreinforced?
The evolution of structural masonry is briefly reviewed, from old thrust line behavior to modern global behavior using shear walls. For modern structural masonry, the use of unreinforced, confined and reinforced masonry is addressed in seismic areas. A first focus is given to recent approaches towards the safety assessment of unreinforced masonry buildings and their performance in shaking table tests. Subsequently, building systems for modern masonry structures recently developed and tested at University of Minho are presented, one based on lightweight concrete blocks and another based on normal concrete blocks. The experimental and numerical work carried out is discussed and conclusions on the performance of the systems are given
Análise experimental do comportamento de paredes de alvenaria de pedra não reforçada sob acções cíclicas no plano
Com o presente trabalho pretende-se efectuar a avaliação experimental do comportamento de paredes de alvenaria de pedra não reforçada, com diferente aparelho das pedras em alçado, submetidas a acções horizontais cíclicas no plano. A análise dos resultados experimentais abrange a caracterização dos mecanismos de rotura, padrões de fendilhação, e a determinação
da resistência última das paredes a acções horizontais cíclicas. Adicionalmente, realiza-se a discussão da resposta em termos de diagramas força-deslocamento, bem como o estudo comparativo da resistência e rigidez lateral para os dois tipos de paredes ensaiadas.Empresa Augusto Ferreira.
Bettor MBT
Numerical computation for initial value problems in economics
We summarise Runge-Kutta type methods for the solution of ordinary differential equations in models of economic dynamics. In this work we are going to present explicit Runge-Kutta type methods, a family of methods to solve numerically systems of ordinary differential equations, without the need to evaluate high-order derivatives. We apply this numerical approach to solve a dynamic, general equilibrium growth model of North-South technological-knowledge diffusion by imitation.North-South; Technological Knowledge Diffusion; Convergence; Numerical Computations
Experimental analysis of reinforced concrete block masonry beams using pre-fabricated planar trussed bars
Masonry spandrels together with shear walls are structural components of a masonry building subjected to lateral loads. Shear walls are the main components of this structural system, even if masonry spandrels
are the elements that ensure the connection of shear wall panels and the distribution of stresses through the masonry piers. The use of prefabricated truss type bars in the transversal and longitudinal directions is usually considered a challenge, even if the simplicity of the applications suggested here alleviate some of the possible difficulties. This paper focus on the experimental behavior of masonry spandrels reinforced with prefabricated trusses, considering different possibilities for the arrangement of reinforcement and blocks. Reinforced spandrels with three and two hollow cell concrete blocks and with different reinforcement ratios have been built and tested using a four and three point loading test configuration. Horizontal bed joint reinforcement increased the capacity of deformation as well as the ultimate load,
leading to ductile responses. Vertical reinforcement increased the shear strength of the masonry spandrels and its distribution play a central role on the shear behavior.This work was partly supported by contract DISWALL - "Development of innovative systems for reinforced masonry walls" - COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme Al(ss)an, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. E06D100148BR
Timber frames as an earthquake resisting system in Portugal
Timber frames are commonly adopted as a structural element in many countries with specific
characteristics varying locally, in termsof geometry and materials.Their diffusion in Southern European countries
is linked to their good seismic-resistant capacity, but only in the last decade interest has grown for this structural
typology, and studies have been performed to better understand their behaviour. In this contribution, a brief
state of the art on existing timber frame building typologies is presented, focusing on their seismic-resistant
characteristics. Additionally, an overview of possible strengthening solutions, adopted both in practice, and
tested experimentally are presented. Their performance when applied to walls and connections is also discussed.(undefined
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