Comparison between tensile properties and indentation properties measured with various shapes indenters of Copper-Chromium-Zirconium alloy at macroscale level

In this paper the experimental results of tensile properties and indentationproperties, as a function of pyramidal and spherical indenters, of Copper-Chromium-Zirconium alloy, in the macro-scale range at room temperature, are presented and compared. Measurements are performed on three Cu-Cr-Zr samples in order to evaluate different heat treatments: two samples areaged for 2 hours in a vacuum furnace at 480 °C, 550 °C and one sample is kept as received. The experimental procedures for the measurement of indentation modulus, by using the primary hardness standard machine at INRiM, and tensile modulus, by means of engineering tensile tests at CIRA, aredescribed

Residual stress generation in tungsten-copper brazed joint using brazing alloy

Understanding the residual stress state in brazed joints is crucial for operational design and life time performance of the part in service. High magnitudes residual stresses are expected in the joined materials following cooling from brazing temperatures (≈950°C) due to large mismatches in material properties such as coefficient of thermal expansion and Young’s modulus. This study aims at further understanding of the generation and distribution of residual stresses when brazing tungsten to copper using a eutectic gold-copper brazing alloy. This configuration is potentially useful for future divertor designs. Finite Element Analysis (FEM) has been used to predict the brazing induced stresses and residual stress measurements were carried out on the brazed joint by X-ray diffraction (XRD) to validate the prediction model. Large residual stresses are predicted and measured in the tungsten; however there is disagreement in the sign of the stress. Predicted stresses are highly tensile in nature close to the brazing interface, whereas the measured stresses are highly compressive. The disagreement is believed to be caused by the model not accurately simulating the complex brazing process. Residual stress measurements on the copper were not possible due to texturing during brazing, grain growth and significant inelastic strains and deformations. Misalignment of parent materials was also observed to significantly affect residual stresses

Residual stress generations in brazed tungsten dissimilar joints

Understanding the residual stress state in brazed joints is crucial for the operational design and lifetime performance of the part in service. High-magnitude residual stresses are expected in the joined materials following cooling from brazing temperatures (≈950 °C) due to large mismatches in the thermal and mechanical properties. This paper aims at further understanding of the residual stresses caused when brazing tungsten to copper and tungsten to 316L austenitic steel using a eutectic gold-copper brazing alloy. These configurations are potentially useful for future diverter designs. Finite element analysis has been used to predict the brazing-induced stresses and residual stress measurements were carried out on the brazed joint by X-ray diffraction to validate the prediction model. Large residual stresses are predicted and measured in the tungsten; however, there is disagreement in the nature of the stress in the tungsten-copper configuration. Predicted stresses are highly tensile in nature close to the brazing interface, whereas the measured stresses are highly compressive. The disagreement is believed to be caused by the model not accurately simulating the complex brazing process. Residual stress measurements on the copper were not possible due to texturing during brazing, grain growth, and significant inelastic strains. There is excellent correlation between the measured and predicted stresses in the tungsten-316L configuration. High-tensile stresses were predicted in the tungsten (magnitude approximately 1000 MPa close to the braze interface) and high tensile stresses were measured (magnitude approximately 800 MPa in the same region). Joint misalignment of parent materials was also observed to significantly affect the residual stresses

The use of hand-held computers (PDAs) to audit and validate eradication of a post-border detection of Khapra Beetle, Trogoderma granarium, in Western Australia

Most of Australia’s agricultural produce is exported. Demonstrating freedom from certain plant and animal pests and diseases is critical to securing and maintaining market access. Surveillance is an important tool in gaining market access and accordingly exporting countries now need to provide accurate, credible evidence to confirm pest freedom status.In the past nearly all field-collected surveillance information was recorded manually to paper reducing the rate of capture, integrity, conformity as well as security of the data. This paper describes the development of pest surveillance data collection software and hardware using PDAs (Personal Digital Assistants) to provide auditing, validation, chain of evidence and increase the volume of data collected as well as its integrity through relational databases and seamless data transfer to corporate systems. The system’s first deployment was during a T. granarium eradication. The khapra beetle (Trogoderma granarium) is one of the most serious pests of stored grain and is a regulated quarantine pest in most countries around the world. In April 2007, there was a post-border detection of T. granarium larvae and adults in a Western Australian residence. Immediate and uncompromising action was taken to quarantine the home and fumigate it with methyl-bromide at an internationally established rate known to control T. granarium (AQIS T9056). A two-year T. granarium trapping program was undertaken which used PDA software to provide evidence of complete eradication via 1273 trap inspections. This achievement was supported by GPSlocated traps, digital voice navigation itineraries, digital time and date stamps, field printed barcode labels, site imagery, all in a single hand-held unit. Keywords: T. granarium, Khapra beetle, Eradication, Biosecurity, PDA, Surveillanc

Electrical coupling of neuro-ommatidial photoreceptor cells in the blowfly

A new method of microstimulation of the blowfly eye using corneal neutralization was applied to the 6 peripheral photoreceptor cells (R1-R6) connected to one neuro-ommatidium (and thus looking into the same direction), whilst the receptor potential of a dark-adapted photoreceptor cell was recorded by means of an intracellular microelectrode. Stimulation of the photoreceptor cells not impaled elicited responses in the recorded cell of about 20% of the response elicited when stimulating the recorded cell. This is probably caused by gap junctions recently found between the axon terminals of these cells. Stimulation of all 6 cells together yielded responses that were larger and longer than those obtained with stimulation of just the recorded cell, and intensity-response curves that deviated more strongly from linearity. Evidence is presented that the resistance of the axon terminal of the photoreceptor cells quickly drops in response to a light flash, depending on the light intensity. Incorporating the cable properties of the cell body and the axon, the resistance of the gap junctions, and the (adapting) terminal resistance, a theoretical model is presented that explains the measurements well. Finally, it is argued that the gap junctions between the photoreceptor cells may effectively uncouple the synaptic responses of the cells by counteracting the influence of field potentials.