bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resting cladoceran eggs and their contribution to zooplankton diversity in a lagoon of the Upper Paraná River floodplain
Authors: Palazzo Fabiana , Bonecker Claudia Costa , Fernandes Ana Paula Capelari 
Published: October 2008

AbstractZooplankton produce resting eggs and diapause stages as strategies to promote their survival during periods of adverse environmental conditions, thereby ensuring the community diversity. The goal of this study is to investigate the contribution of these eggs, which were present in the sediment of an isolated lagoon in the Upper Paraná River floodplain, to cladoceran diversity. The species hatching from the resting eggs in the sediment do not occur in the plankton. Sediment samples were collected at six sampling sites in the Osmar Lagoon banks, in September 2004 and June, July, August and September 2005. Zooplankton were sampled in the pelagic region, using a motorized pump (1000 L) and plankton net (68 µm). The pH, water temperature (°C), electrical conductivity (µS cm−1) and dissolved oxygen concentration (mg L−1) also were measured. The resting eggs were counted in the laboratory, being maintained under constant temperature and photoperiod until their analyses. The resting eggs were examined daily until hatching. A higher abundance of these eggs was observed in July, during a period of lower temperature and electrical conductivity, and higher pH and dissolved oxygen concentrations. ANOVA results indicated significant differences in resting egg abundance among the sampling months. Ceriodaphnia reticulata, Macrothrix spinosa, Ilyocryptus spinifer, Ephemeroporus tridentatus and Diaphanosoma sp. hatched from the resting eggs, although they were not observed in the plankton samples. C. reticulata was observed for the first time in this floodplain, with these study results corroborating the hypothesis that resting cladoceran eggs do contribute to zooplankton diversity in the lagoon.
Biotic Ligand Model estimation of copper bioavailability and toxicity in the Yacyretá Reservoir on the Paraná River
Authors: Natale Oscar E. , Leis Maria V. 
Published: October 2008

AbstractThe Biotic Ligand Model (BLM) was used to assess copper bioavailability, toxicity and water‐effect ratios (WER) for the Yacyretá Reservoir on the Paraná River. Copper in the Yacyretá Reservoir watershed is ubiquitous (median dissolved concentration = 4.4 µg L−1), being contributed mainly by non‐point surface run‐off from citrus fields and urban sewage point sources. BLM simulations indicated that copper bioavailability is negligible, as almost 100% of the dissolved copper is complexed by dissolved organic carbon (DOC). Copper bioavailability in the Paraná River, which has a mean hardness concentration of 16.5 mg CaCO3 L−1, is controlled by the presence of humic substances (≈60% of humic acids) in DOC. BLM estimates of acute toxicity for a cyprinid fish species were of the same order of magnitude as those corresponding to daphnids (EC50 = 63.54 µg L−1). However, zooplankton species were chosen to represent the aquatic biota for water quality regulatory purposes because of their slightly higher sensitivity to copper toxicity. Based on the corresponding minimum WER (14.6) for copper in Yacyretá Reservoir on the Paraná River, a site‐specific copper criterion for the protection of the aquatic biota of 24 µg L−1 was derived. All measured dissolved copper concentrations for Yacyretá Reservoir during the 2001–2002 period were in compliance with this criterion. Development and application of the BLM provides a useful tool for managing metal loads in reservoir environments.
Resettler choices and long‐term consequences of involuntary resettlement caused by construction of Kotmale Dam in Sri Lanka
Authors: Takesada Naruhiko , Manatunge Jagath , Herath Indika Lakshman 
Published: October 2008

AbstractInvoluntary resettlement caused by dam construction, especially in developing countries, is being criticized as an additional cause of impoverishment of the poor population being resettled. Despite current improvements in planning and implementation of involuntary resettlement, there is little experience or research on the medium‐ to long‐term consequences of involuntary resettlement on those being resettled.Within the comprehensive water resource development programme in Sri Lanka under the Mahaweli Accelerated Development Programme, Kotmale Dam was constructed in 1985 for the purpose of hydroelectric power generation and irrigation water supply. Construction of the dam caused ≈ 3000 households to be evacuated and relocated. There were two resettlement alternatives for the families being affected by the dam construction project. The first was to stay close to the reservoir, and receive smaller land plots. The other was to settle in newly developed areas for Mahaweli Development Programme, being located >100 km from original villages, but receive larger, irrigated land plots. In order to determine the consequences after 25 years of the resettlement caused by construction of Kotmale Dam, these authors conducted socioeconomic interview surveys of ≈250 households in three resettlement areas, including Mahaweli System H, System B, System C and villages located near the reservoir site.The study results indicated that the majority of the resettlers perceived their livelihoods as being improved after their resettlement. Furthermore, the majority of them expressed their satisfaction regarding their resettlement choices and their current livelihoods, either in the resettlement sites located near the reservoir or in resettlement sites located far from the original settlement sites. However, their satisfaction is usually based on different perceptions on the part of the resettlers that reflect different strategies for coping with involuntary resettlement. The major factors affecting the choices of resettlers were land ownership and/or the educational opportunities for their children. These survey results indicate that the resettled people made conscious choices for their future, especially for their children. For future resettlement programmes, these authors propose that it is important that the considerations of future generations be incorporated in a feasible, sustainable manner, particularly in regard to educational opportunities.
Thermoelastic investigation of an aluminium helicopter component under non‐adiabatic conditions
Authors: GALLOTTI A. , SALERNO A. , DESIDERATI S. , FANTONI G. 
Published: October 2008

ABSTRACTThermoelastic Stress Analysis (TSA) has been used to analyze an aeronautic cross‐shaped structural component, composed of several riveted parts, made of different aluminium alloys. Due to the high thermal diffusivity of aluminium, some parts of the component were not in adiabatic conditions during the test, causing an attenuation of the temperature peaks, linked to the stress distribution. Furthermore, the presence of a thick primer coating altered the TSA results on the component especially at high frequencies. After the removal of the primer from some parts of the surface, a correction procedure was applied to compensate for the heat diffusion, thus obtaining quantitative results, which proved to be in very good agreement with the stress values obtained by strain gauges.
Mechanical fatigue of an electronic component under random vibration
Authors: C¸ELİK M. , GENC¸ C. 
Published: October 2008

ABSTRACTElectronic equipment, which is widely used in military applications, must be able to survive harsh environments. The endurance of such equipment is defined by the durability of their internal sensitive components. In this study, vibration induced fatigue life analysis of an axial leaded aluminium capacitor is performed. Three point bending tests are performed for the composite FR‐4 printed circuit boards (PCBs) material in order to determine bending modulus. Experimental modal analysis is used to validate a simulation model of the PCB. Step stress tests (SSTs) of reinforced and unreinforced capacitors which are mounted on the test PCBs are performed. It is found that the failure locations on the test PCBs are compatible among themselves and all the failures are due to flexure stress developed at the lead wires and solder joints. Numerical fatigue analyses are performed to define failure in terms of damage index. In addition, the Weibull model is used to define mean time to failure (MTTF) values. The comparison between MTTF values shows that the fatigue lives are strongly increased by the eccobond reinforcement. The last stage in this work is to focus on the influence of some design parameters on the fatigue life. An exponential equation is proposed to find the relation between lead‐wire diameter and the fatigue damage. It is shown that fatigue damage becomes a maximum for a square shaped PCB and it appears that component body diameter is more effective than the body length in increasing fatigue life.
Comparison of the modified three‐rail shear test and the [(+45°,−45°)]ns tensile test for pure shear fatigue loading of carbon fabric thermoplastics
Authors: DE BAERE I. , VAN PAEPEGEM W. , DEGRIECK J. 
Published: October 2008

ABSTRACTThe (three)‐rail shear test is rarely considered for testing of fibre‐reinforced composites under pure shear fatigue loading conditions because of all experimental difficulties. However, in this article, a carbon fabric‐reinforced PPS is tested using a modified three‐rail shear test setup. The results are compared with [(+45°,−45°)]4s tensile tests with good correspondence. All fatigue experiments were done with R= 0 and the influence of maximum shear stress and frequency is investigated. It can be concluded that an increase in maximum shear stress decreases fatigue lifetime, whereas an increase in frequency increases the lifetime. Before failure, a sudden increase in both temperature and permanent deformation could be detected. Creep tests yielded that the occurring deformation is mainly due to the fatigue loading, rather than due to creep phenomena.
Fracture path prediction of diamond segment in a marble cutting disc
Authors: UCUN İ. , ASLANTAS K. , TASGETIREN S. , SEDAT BÜYÜKSAGIS İ. 
Published: October 2008

ABSTRACTThis study investigates the fracture path behaviour of diamond segments that have been brazed on a marble cutting disc. The segments are braze‐joined using the oxy‐gas welding technique. The micro‐structure of the brazing zone and the disc were investigated using standard metallographic techniques and scanning electron microscope (SEM). Additionally, we used numerical modelling to study crack growth at the welding zone. Two dimensional linear elastic fracture mechanics principles were used to analyze propagation behaviour of the crack. Stress intensity factors were calculated using displacement correlation method. It was deduced from the SEM analysis of the fractured segment surface that the fracture occurred in the diamond segment due to stress concentration near the sharp corners of the diamond particles that are embedded into the matrix. The existence of such sharp artefacts within the matrix leads to the formation of cracks.
Fatigue behaviour of friction stir welded AA2024‐T3 alloy: longitudinal and transverse crack growth
Authors: MILAN M. T. , BOSE FILHO W. W. , RUCKERT C. O. F. T. , TARPANI J. R. 
Published: October 2008

ABSTRACTThe fatigue crack growth properties of friction stir welded joints of 2024‐T3 aluminium alloy have been studied under constant load amplitude (increasing‐ΔK), with special emphasis on the residual stress (inverse weight function) effects on longitudinal and transverse crack growth rate predictions (Glinka's method). In general, welded joints were more resistant to longitudinally growing fatigue cracks than the parent material at threshold ΔKvalues, when beneficial thermal residual stresses decelerated crack growth rate, while the opposite behaviour was observed next toKCinstability, basically due to monotonic fracture modes intercepting fatigue crack growth in weld microstructures. As a result, fatigue crack growth rate (FCGR) predictions were conservative at lower propagation rates and non‐conservative for faster cracks. Regarding transverse cracks, intense compressive residual stresses rendered welded plates more fatigue resistant than neat parent plate. However, once the crack tip entered the more brittle weld region substantial acceleration of FCGR occurred due to operative monotonic tensile modes of fracture, leading to non‐conservative crack growth rate predictions next toKCinstability. At threshold ΔKvalues non‐conservative predictions values resulted from residual stress relaxation. Improvements on predicted FCGR values were strongly dependent on how the progressive plastic relaxation of the residual stress field was considered.
Stress intensity factors and crack opening displacements for slanted axial through‐wall cracks in pressurized pipes
Authors: HUH N.‐S. , SHIM D.‐J. , CHOI S. , PARK K.‐B. 
Published: October 2008

ABSTRACTThis paper proposes elastic stress intensity factors and crack opening displacements (CODs) for a slanted axial through‐wall cracked cylinder under an internal pressure based on detailed three‐dimensional (3D) elastic finite element (FE) analyses. The FE model and analysis procedure were validated against existing solutions for both elastic stress intensity factor and COD of an idealized axial through‐wall cracked cylinder. To cover a practical range, four different values of the ratio of the mean radius of cylinder to the thickness (Rm/t) were selected. Furthermore, four different values of the normalized crack length and five different values of the ratio of the crack length at the inner surface to the crack length at the outer surface representing the slant angle were selected. Based on the elastic FE results, the stress intensity factors along the crack front and CODs through the thickness at the centre of the crack were provided. These values were also tabulated for three selected points, that is, the inner and outer surfaces and at the mid‐thickness. The present results can be used to evaluate the crack growth rate and leak rate of a slanted axial through‐wall crack due to stress corrosion cracking and fatigue. Moreover, the present results can be used to perform a detailed leak‐before‐break analysis considering more realistic crack shape development.
Modelling fatigue crack propagation in CT specimens
Authors: BRANCO R. , ANTUNES F. V. , MARTINS R. F. 
Published: October 2008

ABSTRACTAlthough there are a great number of numerical studies focused on the numerical simulation of crack shape evolution, a deeper understanding is required concerning the numerical parameters and the mathematical modelling. Therefore, the objectives of the paper are the study of the influence of numerical parameters, particularly the radial size of crack front elements and the magnitude of individual crack extensions, the mathematical modelling of crack propagation regimes, and the linking of crack shape changes with K distribution. A relatively simple through‐crack geometry, the CT specimen, was studied and the numerical model was validated with experimental results with a good agreement. The K distribution along crack front was found to be the driving force for shape variations. Shape variations were found to be one order of magnitude lower than K variations.
Analytical and numerical modelling of plasticity‐induced crack closure in cold‐expanded holes
Authors: DE MATOS P. F. P. , NOWELL D. 
Published: October 2008

ABSTRACTThe aim of this research was the development of an analytical model for plasticity‐induced fatigue crack closure for cold expanded holes. This paper extends Nowell's plane stress model of plasticity‐induced crack closure for a plate with a circular hole and two radial symmetric cracks. The possibility of existence of an initial residual stress field is also taken into account. This model has potential to be applied to other cracked geometries and arbitrary residual stress fields, although the paper is focused on the study of cold‐expanded holes. Hole cold‐expansion is widely used in aircraft industry, for improving the fatigue performance of rivet holes by delaying fatigue crack propagation. This paper shows that the residual stress field due to cold‐expansion has a strong influence on the closure behaviour and therefore on fatigue crack propagation. The analytical model developed, was compared with finite element analyses of plasticity‐induced crack closure with and without residual stresses. Finally, the model was used to predict fatigue lives for some experiments recently reported in the literature for fatigue crack propagation from cold‐expanded holes. Predicted fatigue lives correlate well with experimental data.
The effect of frequency on the giga‐cycle fatigue properties of a Ti–6Al–4V alloy
Authors: TAKEUCHI E. , FURUYA Y. , NAGASHIMA N. , MATSUOKA S. 
Published: October 2008

ABSTRACTThe effect of frequency on giga‐cycle fatigue properties was investigated in smooth and 0.3 mm‐hole‐notched specimens at three heats (Heats A, B, and C) for a 900 MPa‐class Ti‐6Al‐4V alloy. Fatigue tests were performed at frequencies of 120 Hz, 600 Hz, and 20 kHz using electromagnetic resonance, high‐speed servohydraulic, and ultrasonic fatigue testing machines, respectively. Heats A and B developed internal fractures, and in these cases, frequency effects were negligible. On the other hand, Heat C developed only surface fractures. In this case, high‐frequency tests showed a higher fatigue strength, indicating frequency effects were not negligible. The tests using the notched specimens showed almost no frequency effects regardless of the heat. The frequency effects observed in the cases of surface fracture were believed to be related to a delay in local plastic deformation in response to high‐frequency loading, since temperature increases in these specimens were successfully suppressed. The delay in the plastic deformation was observed to be reduced in the notched specimens because of stress concentration and limitation in the plastic deformation zone. In turn, the significant conclusion of this research is that high‐frequency tests can be applied not only to internal fractures but also to notch problems, but are not applicable to surface fractures of smooth specimens.
The effect of high‐temperature annealing on tensile strength and its mechanism of Hi‐Nicalon SiC fibres under inert atmosphere
Authors: YAO R. Q. , WANG Y. Y. , FENG Z. D. 
Published: October 2008

ABSTRACTHi‐Nicalon SiC (silicon carbide) fibres were annealed in an argon flow for 10 h at 1400 °C, 1600 °C and 1800 °C. The strength of the fibres was determined by a monofilament tensile testing machine, their fracture surfaces were analysed by SEM (scanning electron microscope) and their microstructure was characterized by a TEM (transmission electron microscope) and XRD (X‐ray diffractometer). The results indicated that the strength of the fibres obeyed the Weibull distribution and the tensile strength decreased with the increase of annealing temperatures. The specimens showed brittle/flat fracture; most of the cracks initiated at the inner region of the fibres. After being annealed at 1800 °C for 10 h, the specimens showed cleavage and transcrystalline fracture. Statistical analysis revealed that the defects at the surface of the fibres had a negligible effect on their strength.
The Importance of Survival Units for Norbert Elias's Figurational Perspective
Authors: Kaspersen Lars Bo , Gabriel Norman 
Published: October 2008

In this paper, we argue that Norbert Elias's concept of survival unit is a distinctive part of the development of his figurational sociology and one of the most consistent contributions to relational thinking. The survival unit is a particular form of figuration which provides security and the material foundations for life such as food and shelter. Every human being is born into a survival unit. This unit is a relational concept which cannot be conceived outside a relationship with other survival units. By introducing the concept of survival unit Elias overcomes one of the key problems in relational sociology: how to demarcate primary social relations. Elias argues that human societies from very early on have been divided into survival units. These survival units are demarcated and constituted in their relationship to other survival units. Consequently, their boundaries are generated in a confrontation with other survival units. This relationship can be peaceful or conflict ridden but in the last resort it can end with violent confrontation. Only the survival unit with the ability to defend a domain of sovereignty will survive. This observation places Elias among the few sociologists with an understanding of the role of warfare in social relationships.
The embryo as moral work object: PGD/IVF staff views and experiences
Authors: Ehrich Kathryn , Williams Clare , Farsides Bobbie 
Published: October 2008

AbstractWe report on one aspect of a study that explored the views and experiences of practitioners and scientists on social, ethical and clinical dilemmas encountered when working in the field of preimplantation genetic diagnosis (PGD) for serious genetic disorders. The study produced an ethnography based on observation, interviews and ethics discussion groups with staff from two PGD/IVF Units in the UK. We focus here on staff perceptions of work with embryos that entails disposing of ‘affected’ or ‘spare’ embryos or using them for research. A variety of views were expressed on the ‘embryo question’ in contrast to polarised media debates. We argue that the prevailing policy acceptance of destroying affected embryos, and allowing research on embryos up to 14 days leaves some staff with rarely reported, ambivalent feelings. Staff views are under‐researched in this area and we focus on how they may reconcile their personal moral views with the ethical framework in their field. Staff construct embryos in a variety of ways as ‘moral work objects’. This allows them to shift attention between micro‐level and overarching institutional work goals, building on Casper's concept of ‘work objects’ and focusing on negotiation of the social order in a morally contested field.
Understanding adversity and resilience at older ages
Authors: Hildon Zoe , Smith Glenn , Netuveli Gopalakrishnan , Blane David 
Published: October 2008

AbstractThis mixed‐methods study looks at the relationship between adversity and resilience. It examines the dynamics of protection in a sub‐sample of the Boyd Orr cohort that are aged between 70 and 80 years of age (n = 139). We used a questionnaire and activity diaries to gather a range of quantitative data, and interviews using lifegrids to explore past and present experiences of adversity. Sampling of 32 individuals was based on resilient and vulnerable outcomes (16 cases respectively), measured quantitatively as good or poor quality of life (CASP‐19) in the presence of one or more adversities such as ill health or stress. The analysis explored adversity and protection in relationships, retirement, and health. Participants with resilient outcomes drew upon social and individual resources in the face of adversity, in particular resources that stabilised life change by providing continuity. These included: constructing narratives that reinterpreted past adversity in light of recent ones; maintaining social roles and activities that had previously brought pleasure or a sense of mastery; relying on tried and tested coping strategies; support from close ongoing relationships. Participants with vulnerable outcomes, however, described more severe adversities, suggesting that resilience is also dependent on the degree and impact of this experience.