Kinematic stability of roller pairs in free rolling contact

A set of generalized stability equations was developed for roller pairs in free rolling contact. A symmetric, dual contact model was used. Four possible external contact profiles that possess continuous contacting surfaces were studied. It was found that kinematic stability would be insured if the larger radius of transverse curvature, in absolute value, and the smaller rolling radius both exist on the roller that has the apex of its conical surface outboard of its main body. The stability criteria developed are considered to be useful for assessing axial restraint requirements for a variety of roller mechanisms and in the selection of roller contact geometry for traction drive devices

Application of traction drives as servo mechanisms

The suitability of traction drives for a wide class of aerospace control mechanisms is examined. Potential applications include antenna or solar array drive positioners, robotic joints, control moment gyro (CMG) actuators and propeller pitch change mechanisms. In these and similar applications the zero backlash, high torsional stiffness, low hysteresis and torque ripple characteristics of traction drives are of particular interest, as is the ability to run without liquid lubrication in certain cases. Wear and fatigue considerations for wet and dry operation are examined along with the tribological performance of several promising self lubricating polymers for traction contracts. The speed regulation capabilities of variable ratio traction drives are reviewed. A torsional stiffness analysis described suggests that traction contacts are relatively stiff compared to gears and are significantly stiffer than the other structural elements in the prototype CMG traction drive analyzed. Discussion is also given of an advanced turboprop propeller pitch change mechanism that incorporates a traction drive

Effects of Ultra-Clean and centrifugal filtration on rolling-element bearing life

Fatigue tests were conducted on groups of 65-millimeter bore diameter deep-groove ball bearings in a MIL-L-23699 lubricant under two levels of filtration. In one test series, the oil cleanliness was maintained at an exceptionally high level (better than a class "000" per NAS 1638) with a 3 micron absolute barrier filter. These tests were intended to determine the "upper limit" in bearing life under the strictest possible lubricant cleanliness conditions. In the tests using a centrifugal oil filter, contaminants of the type found in aircraft engine filters were injected into the filters' supply line at 125 milligrams per bearing-hour. "Ultra-clean" lubrication produced bearing fatigue lives that were approximately twice that obtained in previous tests with contaminated oil using 3 micron absolute filtration and approximately three times that obtained with 49 micron filtration. It was also observed that the centrifugal oil filter had approximately the same effectiveness as a 30 micron absolute filter in preventing bearing surface damage

Charedi women, charedi men, and stress

This report examines data from interviews with 179 strictly-orthodox Jews living in London. The impetus was a debate in this journal on the question whether men or women in the strictly-orthodox community are more stressed. Many of the observations made in this journal on the quality of life among charedi men and women were born out. Quantitatively, severe stress and clinical levels of depression and anxiety were similar among the men and women studied, but women had overall more eventful lives than men, and were more likely to suffer from borderline depression and anxiety - though these differences were only marginally significant. It is suggested that the London sample studied were probably similar to charedim in Israel, and that the findings might therefore be applicable

Culturally and religiously sensitive psychological help - from a Jewish perspective

This bit is to tell you something about who I am and where I am coming from. I read recently that it was a good idea to do this before writing up qualitative research, but I can’t see why it can’t be done before writing about any kind of research, or indeed any kind of psychology, qualitative research or otherwise. I am an orthodox Jew, strictly orthodox, and a common corollary of that is having a very large number of children. As the years go by, we have an increasingly large number of grandchildren. I am also an academic psychologist. I started off my academic career in the 1960s by doing a thesis on the relations between thinking and speaking, and particularly the question of whether the outcome of thinking was affected by talking about it. When I began teaching, I felt that I stood with a foot in social psychology, and a foot in cognitive psychology, and for many years I taught both. But I got softer and softer, or perhaps it was harder to find people to teach social psychology, so I began to teach more and more social psychology, and less and less cognitive psychology. Then my boss, the late Brian Foss, met a philosophy professor from Kings College (London), the late Hywel Lewis. Lewis was looking for psychologist to teach the psychology of religion, and I think I was the only psychologist that Brian knew who didn’t think religion was a meaningless word. So I began teaching the psychology of religion, and which got me interested in personality theory, including psychodynamic theory, and psychometrics, as well as doing the kind of research in which the researcher collects accounts of people’s experiences. I am still a bit confused about what personality is, and about what is being measured in psychometrics, but in spite of this - or, more likely, because of this – I began teaching personality, and psychometrics. Meanwhile the number of my children grew, and I began wondering about Brown & Harris’s (1978) report that women with several young children to care for, were more vulnerable to depression. The anthropologist, Jeanette Kupferman (1979) thought that strictly-orthodox Jewish women might be more cheerful in their lifestyle full of boundaries and rules, large families notwithstanding. I wondered who was right. Tirril Harris was very encouraging about the idea of doing a replay of the Brown & Harris Camberwell and Hebridean studies among orthodox Jews, and I was happy to get some funding for this work. This led me deeper and deeper into issues relating religion and mental health. As the younger children grew older, I began to write and publish more and more on different aspects of religion and mental health

Features associated with speaking in tongues (glossolalia)

Reports of the frequency, context, associated behaviours, feelings and meaning associated with glossolalia were collected from three groups of informants: speakers (n=14, who practised glossolalia), witnesses (n=15, who had witnessed but had never practised glossolalia), controls (n=16, who had neither witnessed nor practised glossolalia). All informants were practising Christians. Speakers reported glossolalia as a regular, daily, private activity, usually accompanying mundane activities, as a special form of prayer associated with calm, pleasant emotions. By contrast, witnesses and controls were more likely to describe glossolalia as an exceptional activity, usually occurring in the religious group, and associated with excitement. The views of witnesses were closer to those of speakers than were the views of controls. It is suggested that there may be two types of glossolalia, of which one is more likely to be associated with psychopathology

Intense summer floods may induce prolonged increases in benthic respiration rates of more than one year leading to low river dissolved oxygen

The supply of readily-degradable organic matter to river systems can cause stress to dissolved oxygen (DO) in slow-flowing waterbodies. To explore this threat, a multi-disciplinary study of the River Thames (UK) was undertaken over a six-year period (2009–14). Using a combination of observations at various time resolutions (monthly to hourly), physics-based river network water quality modelling (QUESTOR) and an analytical tool to estimate metabolic regime (Delta method), a decrease in 10th percentile DO concentration (10-DO, indicative of summer low levels) was identified during the study period. The assessment tools suggested this decrease in 10-DO was due to an increase in benthic heterotrophic respiration. Hydrological and dissolved organic carbon (DOC) data showed that the shift in 10-DO could be attributed to summer flooding in 2012 and consequent connection of pathways flushing degradable organic matter into the river. Comparing 2009–10 and 2013–14 periods, 10-DO decreased by 7.0% at the basin outlet (Windsor) whilst median DOC concentrations in a survey of upstream waterbodies increased by 5.5–48.1%. In this context, an anomalous opposing trend in 10-DO at one site on the river was also identified and discussed. Currently, a lack of process understanding of spatio-temporal variability in benthic respiration rates is hampering model predictions of river DO. The results presented here show how climatic-driven variation and urbanisation induce persistent medium-term changes in the vulnerability of water quality to multiple stressors across complex catchment systems

An advanced pitch change mechanism incorporating a hybrid traction drive

A design of a propeller pitch control mechanism is described that meets the demanding requirements of a high-power, advanced turboprop. In this application, blade twisting moment torque can be comparable to that of the main reduction gearbox output: precise pitch control, reliability and compactness are all at a premium. A key element in the design is a compact, high-ratio hybrid traction drive which offers low torque ripple and high torsional stiffness. The traction drive couples a high speed electric motor/alternator unit to a ball screw that actuates the blade control links. The technical merits of this arrangement and the performance characteristics of the traction drive are discussed. Comparisons are made to the more conventional pitch control mechanisms