Results from the Apollo passive seismic experiment

Recent results from the Apollo seismic network suggest that primitive differentiation occurred in the outer shell of the moon to a depth of approximately 300 km; and the central region of the moon is presently molten to a radius of between 200 and 300 km. If early melting to a depth of 300 to 400 km was a consequence of accretional energy, very short accretion times are required. The best model for the zone of original differentiation appears to be a crust 40 to 80 km thick, ranging in composition from anorthositic gabbro to gabbro; overlying an ultramafic cumulate (olivine-pyroxene) about 250 km thick. The best candidate for the molten core appears to be iron or iron sulphide. A new class of seismic signals has recently been identified that may correspond to shallow moonquakes. These are rare, but much more energetic than the more numerous, deep moonquakes

Results from the Apollo passive seismic experiment

Recent results from the Apollo Seismic Network suggest that primitive differentiation occurred in the outer shell of the moon to a depth of approximately 300 km and the central region of the moon is presently molten to a radius of between 200 and 300 km. If early melting to a depth of 300 to 400 km was a consequence of accretional energy, very short accretion times are required. It was shown that the best model for the zone of original differentiation is a crust 40 to 80 km thick, ranging in composition from anorthositic gabbro to gabbro, and overlying an ultramafic cumulate about 250 km thick. The best candidate for the molten core appears to be iron or iron sulphide. A new class of seismic signals recently were identified that may correspond to shallow moonquakes. These are rare, but much more energetic than the more numerous, deep moonquakes

Crack path and fracture analysis in FSW of small diameter 6082-T6 aluminium tubes under tension-torsion loading

This paper reports part of the work done in a research project aimed at developing an optimised process to join 38. mm diameter tubes of 6082-T6 aluminium alloy using friction stir welding (FSW), and then to determine the fatigue performance under tension, torsion and tension-torsion loading conditions. The final outcome of the project is intended to be guidance for fatigue design of small diameter aluminium tubes joined by FSW, and this paper presents information on crack path and defects under the various loading conditions. Crack path analysis was performed using both low magnification stereo microscopy and scanning electron microscopy, in order to identify crack initiation sites, the direction of crack propagation and the interrelated influence of microstructure and weld geometry on the crack initiation path

Friction stir welds in aluminium: design S-N curves from statistical analysis of literature data

Appropriate S-N fatigue design curves for friction stir (FS) welded joints in aluminium alloys are currently not specified in design codes and standards. The present paper is intended to assist in enabling standardised fatigue design for such joints, through a comprehensive statistical analysis of more than 500 individual sets of data gathered from published literature. These data are used to establish the usual design fatigue curves for welds that give a 97.7% survival probability with 95% confidence. Experimental fatigue data represent defect-free butt joints and include both flat plate and tubular joints between similar aluminium alloys (across the range of 2xxx, 5xxx, 6xxx, and 7xxx series). Weld conditions include as-welded, machined, and post-weld heat treated under constant amplitude cyclic loading at various stress ratios in the range from R = -1 to 0.5. A systematic comparison is presented by categorising the data according to the alloy type, temper condition, postweld heat treatment and stress ratio and the correlation with the S-N design curves from Eurocode 9 is also considered. The fatigue curves presented in this paper will serve as a useful guideline for engineers involved in design of friction stir aluminium joints subjected to in-service fatigue loading

Technical Innovation Case Report: Ultrasound-Guided Prolotherapy Injection for Insertional Achilles Calcific Tendinosis

We describe the use of ultrasound guidance for hyperosmolar dextrose (prolotherapy) injection of the distal calcaneal tendon specifically just anterior to identified enthesophytes in patients with insertional Achilles calcific tendinosis refractory to conservative treatment. This specific technique has not to our knowledge been described or used in literature previously

The Aging Workforce: Realities, Myths and Implications for Organizations

As the baby boom generation moves gradually toward retirement age, the demographics of the workforce are changing. Yet most organizations are ill prepared to meet the challenges associated with these changes. Fortunately, an increasing amount of research is suggesting ways in which organizations can implement effective management practices for older workers. This forward-thinking book examines common preconceptions about the graying workforce and explodes myths to separate fact from fiction. Because of their professional expertise, workers over the age of 60 will continue to be important contributors to organizations, but what are their special needs, strengths, and weaknesses? How does age affect cognitive performance, job attitudes, and motivation? How do age stereotyping and employment discrimination affect older adults? What kinds of employment patterns will typify older workers? How can they best be attracted and retained? The authors of this book provide state of the science answers to these questions. Psychologists, policymakers, and human resource personnel will find that the discussion in this timely book provides the impetus for creative solutions to future organizational challenges