Bonvissuto¹ GL, CA Busso²

Phyton-International Journal of Experimental Botany, Vol.76, pp. 47-59, 2007, DOI:10.32604/phyton.2007.76.047

Abstract Seed rain has ecological consequences on plant community structure. This study was conducted in the Monte Austral Neuquino nearby the town of Picún Leufú, Province of Neuquén, Argentina, within an area of 15 km x 15 km (39º 20 32' S; 69º19 30' W). Studies were conducted at two sites, distant 1.5 km from one another. Vegetation is distributed on the soil surface as vegetation patches. Four superficial locations may be found in the soil of these patches: location 1, small dune accumulated under the lee; location 2, found at the edge of the small… More >

Serrano-Bernardo F¹, JL Rosúa¹, M Díaz-Miguel²

Phyton-International Journal of Experimental Botany, Vol.76, pp. 27-38, 2007, DOI:10.32604/phyton.2007.76.027

Abstract The Mediterranean region is considered one of the most important zones worldwide in terms of plant diversity. Sierra Nevada (S Spain) is a unique mountain massif within the high-mountain systems of the Mediterranean. It is of great floristic importance and very rich in endemic species. However, it requires numerous tasks for restoring plant cover due to the constant anthropic degradation, especially because of the ski station located near the second-highest peak of the mountain. One of the restoration efforts consists of trying to reproduce, in the laboratory, the ideal conditions to pre-germinate seeds of some… More >

Aleš Belšak¹, Jurij Prezelj²

Structural Durability & Health Monitoring, Vol.3, No.4, pp. 239-246, 2007, DOI:10.3970/sdhm.2007.003.239

Abstract Noise source vizualization represents an important tool in the field of technical acoustics. There are many different techniques of noise source visualization. Most of them, however, are intended for a specific noise source in a specific type of acoustic environment. Consequently, a certain visualization method can be used only for certain types of noise sources in a specific acoustic environment and in a restricted frequency area. This paper presents a new visualization method of complex noise sources on the basis of the use of an acoustic camera. A new algorithm has been used, which makes More >

Guocai Chai

Structural Durability & Health Monitoring, Vol.3, No.3, pp. 191-196, 2007, DOI:10.3970/sdhm.2007.003.191

Abstract Duplex stainless steels (DSS) are a group of steels consisting of approximately equal volume fraction of austenite and ferrite. In this study, the influences of the factors such as hydrogen, ferrite phase, cold deformation, grain size, and cluster due to the spinodal decomposition and precipitates or secondary phases in a super duplex stainless steel on the ductile to brittle transition (DBT) are investigated. Three types of DBT curves: toughness versus temperature, hardness and amount of precipitates, have been built to describe the DBT behavior in DSS. These curves are important to provide the information about More >

S. Beyer¹, Ch. Zhang², S. Hirose³, J. Sladek, V. Sladek⁴

Structural Durability & Health Monitoring, Vol.3, No.3, pp. 177-190, 2007, DOI:10.3970/sdhm.2007.003.177

Abstract This paper presents a hypersingular time-domain boundary element method (BEM) for transient dynamic crack analysis in two-dimensional (2-D), homogeneous, anisotropic and linear elastic solids. A finite crack in an infinite or a finite solid subjected to impact loading conditions is investigated. A combination of the classical displacement boundary integral equations (BIEs) on the external boundary and the hypersingular traction BIEs on the crack-faces is applied. The present BEM uses the time-domain dynamic fundamental solutions for anisotropic solids derived by Wang and Achenbach (1994). An explicit time-stepping scheme based on collocation method is developed. Numerical examples More >

Jean-Jacques Sinou¹

Structural Durability & Health Monitoring, Vol.3, No.3, pp. 133-164, 2007, DOI:10.3970/sdhm.2007.003.133

Abstract This paper aims to establish a damage identification methodology, called the Frequencies' Ratio Surfaces Intersection method (FRSI-method), for predicting not only the location and depth of the crack but also the crack orientation in a circular cross section beam. Two new criterions %Δ_i^cracked and %ψ_i,j^cracked that consider only the ratio of the natural frequencies of the cracked beam are introduced and discussed in order to detect the crack parameters. In order to avoid worse diagnostic, it is demonstrated that a robust identification of crack location is possible by investigating the emergence of extra antiresonance peaks… More >

S.P.L. Leme¹, M.H. Aliabadi², L.M. Bezerra¹, P.W. Partridge¹

Structural Durability & Health Monitoring, Vol.3, No.3, pp. 121-132, 2007, DOI:10.3970/sdhm.2007.003.121

Abstract The coupled electromechanical behaviour of a thin piezoceramic sensor bonded to a stiffened panel subjected to membrane mechanical loadings is examined. The sensor is characterised by an electrostatic line model bonded to a damaged panel modelled by the dual boundary element method. Numerical results obtained demonstrate that the proposed method is capable of modelling changes in the signal output due to presence of cracks. Also presented is a numerical model for detecting fatigue crack growth in a stiffened panel using piezoceramic sensors. More >

Ralf G. Cuntze¹

Structural Durability & Health Monitoring, Vol.3, No.2, pp. 87-106, 2007, DOI:10.3970/sdhm.2007.003.087

Abstract The paper deals with the application of phenomenological, invariant-based strength conditions (fracture failure) and their interrelationships. The conditions have been generated and are just applied here for a variety of materials. These might possess a dense or a porous consistency, and belong to brittle and ductile behaving isotropic materials, brittle unidirectional laminae and brittle woven fabrics. The derivation of the conditions was based on the author's so-called Failure Mode Concept (FMC) which basically builds up on the hypotheses of Beltrami and Mohr-Coulomb.
Essential topics of the paper are: 'global fitting' versus 'failure mode fitting', a short… More >

M. Kumosa¹

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 35-50, 2007, DOI:10.3970/sdhm.2007.003.035

Abstract This paper deals with the structural integrity and durability of suspension composite (non-ceramic, polymer) insulators widely used in power transmission systems around the world. Under certain conditions, the insulators can fail in-service both electrically and mechanically resulting in the drop of energized transmission lines and power outages. In this work, predominantly mechanical failures of the insulators are discussed. In particular, the most important characteristics of a catastrophic failure process called brittle fracture are described. Subsequently, two examples of insulator failures by brittle fracture are shown and their causes explained. Finally, several recommendations on how to More >

C.P. Providakis¹

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 29-34, 2007, DOI:10.3970/sdhm.2007.003.029

Abstract Actuators are structures that give micro-electro-mechanical systems (MEMS) the ability to interact with their environment rather than just passively sensing it. Recent studies of MEMS thermal micro-actuators have shown that simple in design and production devices can provide deflection of the order of 10 μm at low voltages. Recently, metals and single-crystal silicon materials were included in the range of materials used for thermal actuators since they operate at lower temperatures than the commonly used (poly)silicon devices. These actuators are liable to meet the loads in service, so the corresponding integrity and stability analysis constitutes a… More >