Reduction of gear pair transmission error with tooth profile modification

The gear noise problem that widely occurs in power transmission systems is typically characterised by one or more high amplitude acoustic signals. The noise originates from the vibration of the gear pair system caused by transmission error excitation that arises from tooth profile errors, misalignment and tooth deflections. This paper aims to further research the effect of tooth profile modifications on the transmission error of gear pairs. A spur gear pair was modelled using finite elements, and the gear mesh was simulated and analysed under static conditions. The results obtained were used to study the effect of intentional tooth profile modifications on the transmission error of the gear pair. A detailed parametric study, involving development of an optimisation algorithm to design the tooth modifications, was performed to quantify the changes in the transmission error as a function of tooth profile modification parameters as compared to an unmodified gear pair baseline

Comfort Levels When Presented with Interpersonal Stressors as a Function of Sibling Status

This study was designed to examine how people with siblings and people without siblings (only children) handle situations of interpersonal tension and confrontation. In order to examine this additional data about sibling status was collected via a follow-up survey from participants in a previous study. In the previous study, University of Maine female students were told that they were going to be assessed on a two-minute speech about their future plans and goals by a male participant in another room. Throughout this experiment physiological and self-report measures were taken. The 137 participants in this study were contacted via telephone and email and were asked to participate in the follow-up survey regarding their sibling status. Thirty five women answered the survey, 6 of whom were only children. Most were between 18 and 21 years of age, although one participant was 42 years old. The major hypothesis was that only children would show greater indication of stress than children with siblings. Despite the small sample size, some interesting results were obtained. Although there was no significant difference between those with siblings and those without for the baseline resting blood pressure, we found that during the two minute speech task only children showed a lower mean blood pressure than children with siblings. We also looked at self- report measures and another interesting thing was discovered. Here again, contrary to the hypothesized outcome, children with siblings reported higher depressed mood after receiving critical assessment when compared with only children. Additionally, a significant correlation was obtained between the number of years a participant lived with her siblings and her positivity about the upcoming task as well as her level of certainty with regards to her performance. The longer participants lived with their siblings the more they felt that the upcoming task was not a positive challenge and the more uncertain they felt about their performance on the task. A stress measure was computed by combining three of the stress questions: 1) the upcoming task is very stressful; 2) a poor performance on this task would be distressing to me; and 3) I think the upcoming task represents a threat. This stress measure correlated with the regularity with which siblings fought. The more a participant reported having fought with siblings, the more stress she reported about the upcoming task. Similarly, there was a positive correlation between the amount siblings fought and their blood pressure in the minute leading up to their speech task. Overall, the findings suggest that the experience with siblings during childhood may greatly affect the way those with siblings handle situations of interpersonal tension later on in life

Stationary and non-stationary fluid flow of a Bose-Einstein condensate through a penetrable barrier

We experimentally study the fluid flow induced by a broad, penetrable barrier moving through an elongated dilute gaseous Bose-Einstein condensate. The barrier is created by a laser beam swept through the condensate, and the resulting dipole potential can be either attractive or repulsive. We examine both cases and find regimes of stable and unstable fluid flow: At slow speeds of the barrier, the fluid flow is stationary due to the superfluidity of the condensate. At intermediate speeds, we observe a non-stationary regime in which the condensate gets filled with dark solitons. At faster speeds, soliton formation completely ceases and a remarkable absence of excitation in the condensate is seen again.Comment: 4 pages, 4 figure

Effect of surface roughness on friction behaviour of steel under boundary lubrication

The friction behaviour of grinded and polished surfaces was evaluated by using a reciprocal sliding tester under lubrication with PAO, PAO + ZnDTP and PAO + ZnDTP + MoDTC. Friction coefficients on the smooth surfaces showed higher values compared to those on the rough surfaces. For lubrication incorporating PAO and PAO + ZnDTP + MoDTC, friction coefficients on both the smoothest and the roughest surfaces decreased with sliding time. On the other hand, friction coefficients between these extremes decreased with sliding time. In this paper, the effects of surface roughness on friction behaviour are discussed

Cancer immunology and canine malignant melanoma: a comparative review

Oral canine malignant melanoma (CMM) is a spontaneously occurring aggressive tumour with relatively few medical treatment options, which provides a suitable model for the disease in humans. Historically, multiple immunotherapeutic strategies aimed at provoking both innate and adaptive anti-tumour immune responses have been published with varying levels of activity against CMM. Recently, a plasmid DNA vaccine expressing human tyrosinase has been licensed for the adjunct treatment of oral CMM. This article reviews the immunological similarities between CMM and the human counterpart; mechanisms by which tumours evade the immune system; reasons why melanoma is an attractive target for immunotherapy; the premise of whole cell, dendritic cell (DC), viral and DNA vaccination strategies alongside preliminary clinical results in dogs. Current “gold standard” treatments for advanced human malignant melanoma are evolving quickly with remarkable results being achieved following the introduction of immune checkpoint blockade and adoptively transferred cell therapies. The rapidly expanding field of cancer immunology and immunotherapeutics means that rational targeting of this disease in both species should enhance treatment outcomes in veterinary and human clinics