Optimising the design of a piston-ring pack using DoE methods

This paper shows how design of experiments can be used with a ring-pack simulation program to optimise the design of a piston-ring assembly. Ten factors are varied—six describing the ring profile, three ring tensions, and the lubricant viscosity. Statistical analysis shows that there are some significant interactions between some of the factors—an issue that should be considered when performing test- bed measurements on engines. It is shown that an improved design can be achieved that reduces ring losses by 57% whilst reducing upward oil flow by 39%. This could lead to a 7% improvement in fuel economy provided there are no deleterious effects in other parts of the engine

On the Design and Lubrication of Water‐Lubricated, Rubber, Cutlass Bearings Operating in the Soft EHL Regime

All propeller‐driven ships employ a drive shaft supported by journal bearings. To avoid water pollution, these bearings are generally lubricated by the surrounding water, removing the need for a rear seal. Such bearings, commonly referred to as Cutlass bearings, usually have an inner grooved nitrile rubber lining. The grooves (called flutes) allow debris to be flushed out and the bearing surface to be cooled. The remaining area is divided into a number of load‐carrying areas called staves. At present, no rigorous design guide exists for these bearings. This paper presents a methodology to predict the minimum film thickness between the journal and the most heavilyloaded stave, an approach not hitherto reported in the literature. The method includes a new, 3D, finite element (FE) approach for soft elasto‐hydrodynamic (EHL) predictive modelling of generated pressures in cutlass bearings. Model predictions compare favourably with experimental data. It is shown that the modulus of elasticity of the rubber has no influence on the minimum film thickness. An equation relating dimensionless film thickness to dimensionless load, clearance ratio and numbers of staves is presented. For a nominally circular bearing, increasing the clearance ratio or increasing the numbers of staves reduces load‐carrying capacity. It is shown that distortion due to loading can increase load‐carrying capacity

Tobacco Plant Harvester

A harvester for tobacco plants is provided for towing by a prime mover to which an articulated frame is attached, the frame mounting a movable turret having spears on which tobacco stalks are impaled. During removal of the stalks from the spears, they are loaded on sticks which are then manually removed from the harvester. A hydraulic system powered from the prime mover serves to actuate each of the turrets, an empty stick supplying mechanism, a loaded stick removing mechanism, and the mechanism for transferring stalks from the spears to the sticks; and a mechanical power takeoff shaft driven by the prime mover drives the conveyor which moves stalks after being cut from their root systems to the turret for impaling on the spears

A Bibliography for Mount Ktaadn

A list of articles that describe, at least briefly, Mount Katahdin in Maine. Includes a special index to articles that appeared in Appalachia, and a list of notable expeditions in chronological order, beginning with 1736

A Bibliography for Mt. Ktaadn, Revised

A list of articles that describe, at least briefly, Mount Katahdin in Maine. A revised version of a similar list that appeared in December, 1922. Reprinted from Appalachia, Appalachian Mountain Club, December, 1924

A Bibliography for Katahdin: Supplement

From the introduction: The titles here listed are supplementary to “A Bibliography for Mt. Ktaadn, Revised,” published in Appalachia, Vol. 16, No. 1, December, 1924. Many of the additions, of a scientific nature, for this supplement were very kindly furnished by Mr. Arthur H. Norton, of the Portland Society of Natural History, Portland, Maine. The spelling “Ktaadn,” appearing in the title of the earlier bibliography, was used by Briggs, Greenleaf, Hamlin, Harvey, Holley, Hubbard, Jackson, Lawrence, L. H. Merrill, C. E. Potter, Thoreau, and Trumbull. It was at one time in use by the Appalachian Mountain Club. The spelling “Katahdin” is in common use in the State of Maine. It was officially adopted by the United States Geographic Board April 4, 1893, and by the Appalachian Mountain Club in 1925

Polarization errors associated with birefringent waveplates

Although zero-order quartz waveplates are widely used in instrumentation that needs good temperature and field-of-view characteristics, the residual errors associated with these devices can be very important in high-resolution polarimetry measurements. How the field-of-view characteristics are affected by retardation errors and the misalignment of optic axes in a double-crystal waveplate is discussed. The retardation measurements made on zero-order quartz and single-order 'achromatic' waveplates and how the misalignment errors affect those measurements are discussed

Strength is negatively associated with depression and accounts for some of the sex difference A replication and extension

Background Depression occurs about twice as often in women as in men, a disparity that remains poorly understood. In a previous publication, Hagen and Rosenstrom predicted and found that grip strength, a highly sexually dimorphic index of physical formidability, mediated much of the effect of sex on depression. Striking results like this are more likely to be published than null results, potentially biasing the scientific record. It is therefore critical to replicate and extend them. Methodology Using new data from the 2013-14 cycle of the National Health and Nutrition Examination Survey, a nationally representative sample of US households (n = 3650), we replicated models of the effect of sex and grip strength on depression reported in Hagen and Rosenstrom, along with additional potential confounds and a new detailed symptom-level exploration. Results Overall, the effects from the original paper were reproduced although with smaller effect sizes. Grip strength mediated 38% of the effect of sex on depression, compared to 63% in Hagen and Rosenstrom. These results were extended with findings that grip strength had a stronger association with some depression symptoms, like suicidality, low interest and low mood than with other symptoms, like appetite changes. Conclusions Grip strength is negatively associated with depression, especially its cognitive-affective symptoms, controlling for numerous possible confounds. Although many factors influence depression, few of these reliably occur cross-culturally in a sex-stratified manner and so are unlikely to explain the well-established, cross-cultural sex difference in depression. The sex difference in upper body strength occurs in all populations and is therefore a candidate evolutionary explanation for some of the sex difference in depression. Lay summary: Why are women at twice the risk of developing depression as men? Depression typically occurs during social conflicts, such as physical or sexual abuse. Physically strong individuals can often single-handedly resolve conflicts in their favor, whereas physically weaker individuals often need help from others. We argue that depression is a credible cry for help. Because men generally have greater strength than women, we argue that men may be more likely to resolve conflicts using physical formidability and women to signal others for help. We find that higher grip strength is associated with lower depression, particularly symptoms like feeling down or thoughts of suicide and that strength accounts for part of the sex difference in rates of depression.Peer reviewe

Automated Scenario Generation Environment

Report describes IST\u27s investigation into the feasibility of automating the process of planning and scenario generation for large scale (joint level) simulation exercises and development of an architecture for that purpose