Bearing damage characteristics of fibre-reinforced countersunk composite bolted joints subjected to quasi-static shear loading

This paper studies the progression of damage in carbon fibre-reinforced polymer (CFRP) countersunk composite bolted joints (CBJs) with neat-fit clearance, subjected to quasi-static loading. Damage mechanisms, comprising of fibre buckling and breakage, matrix damage, shear damage and inter-laminar delamination within the CFRP composite parts of the joints have been studied. Load-displacement curves, X-ray and optical microscopic images in single- and three-bolt CBJs were used to investigate damage and deformation characteristics. The observations were then employed to further investigate the type of failure and the extent of damage. The evolution of damage within the composite parts was correlated to the failure characteristics of the joints: It was found that the type and extension of damage is strongly correlated with the ultimate failure load point of the joint in single-bolt CBJs. A combined inter/intra-laminar damage consisting of fibre cluster breakage, extensive fibre buckling, debonding and delamination was observed at the ultimate failure load. This study was then extended to three-bolt CBJ where damage surrounding each bolt and its corresponding failure load was strongly correlated: The final study showed that the ultimate failure point in single-bolt CBJ and the first-bolt-failure point in three-bolt CBJ correspond to the composite plies undergoing intra-laminar damage with the size reaching to the edge of the countersunk head. This damage developed extensively through the thickness of the composite parts underneath the countersink, and in the direction opposite to the loading direction. Outside the countersunk head, debonding and delamination were found to be the dominant damage driving mechanisms. Finally, a new design rule has been proposed to predict the response of multi-bolt joints (damage area and failure load) by using the response in single-bolt CBJ as an initial baseline

Analytical and experimental investigations of low level acceleration measurement techniques

Construction techniques for accelerometer with low level threshold sensitivit

Temperature readout system for a strapdown gyro system

Temperature readout system for strapdown IMU assembl

Colorado Ultraviolet Transit Experiment Data Simulator

The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on-board a low-resolution (R~2000--3000), near-ultraviolet (2500--3300 {\AA}) spectrograph. It has a rectangular primary Cassegrain telescope to maximize the collecting area. CUTE, which is planned for launch in Spring 2020, is designed to monitor transiting extra-solar planets orbiting bright, nearby stars aiming at improving our understanding of planet atmospheric escape and star-planet interaction processes. We present here the CUTE data simulator, which we complemented with a basic data reduction pipeline. This pipeline will be then updated once the final CUTE data reduction pipeline is developed. We show here the application of the simulator to the HD209458 system and a first estimate of the precision on the measurement of the transit depth as a function of temperature and magnitude of the host star. We also present estimates of the effect of spacecraft jitter on the final spectral resolution. The simulator has been developed considering also scalability and adaptability to other missions carrying on-board a long-slit spectrograph. The data simulator will be used to inform the CUTE target selection, choose the spacecraft and instrument settings for each observation, and construct synthetic CUTE wavelength-dependent transit light curves on which to develop the CUTE data reduction pipeline.Comment: Accepted for publication in the Journal of Astronomical Telescopes, Instruments and System

Quinoline-resistance reversing agents for the malaria parasite Plasmodium falciparum

Resistance to quinoline antimalarials, especially to chloroquine and mefloquine has had a major impact on the treatment of malaria worldwide. In the period since 2000, significant progress has been made in understanding the origins of chloroquine resistance and to a lesser extent mefloquine resistance in Plasmodium falciparum. Chloroquine resistance correlates directly with mutations in the pfcrt gene of the parasite, while changes in another gene, pfmdr1, may also be related to chloroquine resistance in some strains. Mutations in pfcrt do not appear to correlate with mefloquine resistance, but some studies have implicated pfmdr1 in mefloquine resistance. Its involvement however, has not been definitively demonstrated. The protein products of these genes, PfCRT and Pgh-1 are both located in the food vacuole membrane of the parasite. Current evidence suggests that PfCRT is probably a transporter protein. Chloroquine appears to exit the food vacuole via this transporter in resistant PfCRT mutants. Pgh-1 on the other hand, resembles mammalian multi-drug resistance proteins and appears to be involved in expelling hydrophobic drugs from the food vacuole. Resistance reversing agents are believed to act by inhibiting these proteins. The currently known chloroquine- and mefloquine-resistance reversing agents are discussed in this review. This includes a discussion of structure-activity relationships in these compounds and hypotheses on their possible mechanisms of action. The status of current clinical applications is also briefly discussed

The transdiagnostic process of perfectionism

The transdiagnostic approach to theory and treatment of psychological disorders is gaining increasing interest. A transdiagnostic process is one that occurs across disorders and explains their onset or maintenance. The purpose of this review is to provide evidence that perfectionism is a transdiagnostic process that it is elevated in anxiety disorders, eating disorders, depression, obsessive compulsive personality disorder and somatoform disorders. Data are also reviewed to show that perfectionism can explain aetiology as it is a prospective predictor of depression and eating disorders. Perfectionism is also demonstrated to predict poorer outcome to treatment for anxiety disorders, eating disorders and depression, suggesting the need for specific treatment of perfectionism. Evidence is provided to demonstrate that perfectionism can be successfully treated with cognitive behavioural therapy which results in reduction in psychopathologies. Clinical guidelines are outlined to assist in treatment planning for individuals with elevated perfectionism

Low-Frequency Radio Transients in the Galactic Center

We report the detection of a new radio transient source, GCRT J1746-2757, located only 1.1 degrees north of the Galactic center. Consistent with other radio transients toward the Galactic center, this source brightened and faded on a time scale of a few months. No X-ray counterpart was detected. We also report new 0.33 GHz measurements of the radio counterpart to the X-ray transient source, XTE J1748-288, previously detected and monitored at higher radio frequencies. We show that the spectrum of XTE J1748-288 steepened considerably during a period of a few months after its peak. We also discuss the need for a more efficient means of finding additional radio transients