The Mapping of Elastohydrodynamic Contacts

The paper describes an interferometric method of determining the shape and thickness of the clastohydrodynamic oil film formed between a rotating ball loaded against a diamond, sapphire, or glass plate, and a rotating roller loaded against a glass plate. The film shape for both point and line contact is found to depend critically on speed and load. It is found that considerable departure from the static Hertzian shape occurs at quite low speeds. The line contact results show the extent of the end closure and its dependence on the blend radius of the roller.     

Nuclear Data Sheets for A = 35

The experimental data are evaluated for known nuclides of mass number A=35 (Na,Mg,Al,Si,P,S,Cl,Ar,K, Ca). Detailed evaluated level properties and related information are presented, including adopted values of level and γ-ray energies, decay data (energies, intensities and placement of radiations), and other spectroscopic data. This work supersedes earlier full evaluations of A=35 published by 1990En08 (also 1998En04 update) and 1978En02.No excited states are known in ³⁵Na, ³⁵Mg, ³⁵Ca. No γ rays are known in 35K. Experimental data for ³⁵Al and ³⁵Si are limited and their radioactive decay schemes seem incomplete in view of large Q values and known excitations much below than allowed by Q values. The ³⁵S, ³⁵Cl and ³⁵Ar nuclides remain as the most extensively studied from many different reactions and decays.     

The role of built environment energy efficiency in a sustainable UK energy economy

Energy efficiency in the built environment can make significant contributions to a sustainable energy economy. In order to achieve this, greater public awareness of the importance of energy efficiency is required. In the short term, new efficient domestic appliances, building technologies, legislation quantifying building plant performance, and improved building regulations to include installed plant will be required. Continuing these improvements in the longer term is likely to see the adoption of small-scale renewable technologies embedded in the building fabric. Internet-based energy services could deliver low-cost building energy management and control to the mass market enabling plant to be operated and maintained at optimum performance levels and energy savings quantified. There are many technology options for improved energy performance of the building fabric and energy systems and it is not yet clear which will prove to be the most economic. Therefore, flexibility is needed in legislation and energy-efficiency initiatives.     

The Heat Transfer Coefficient and Lubricated Contact Temperature

This paper is one of a series dealing with the surface temperature conditions in disks and gears. It attempts to apply and extend the theory proposed in an earlier paper which predicted the behavior of the surface temperature of machine elements subjected to repeated frictional contacts. In considering the critical temperature hypothesis proposed by Blok as a criterion for failure by scuffing, it is essential that the operating surface temperature is taken into account in addition to the well known “flash temperature.” There have been many papers referrinq to this “flash temperature,” but little is known of the factors which affect the operating surface temperature, commonly called the bulk temperature. This paper demonstrates that the bulk temperature growth under loaded conditions can be predicted theoretically, and that by observing the behavior of the surface temperature the heat transfer coefficient and friction conditions can be calculated. Finally full details of the thermocouple used by the authors in their tests are given.     

Hot Tear Susceptibility of Al-Mg-Si-Fe Alloys with Varying Iron Contents

Hot tear susceptibility in cast Al-0.52Si-0.34Mg-xFe 6060 aluminum alloys was investigated using a hot tearing test apparatus to simulate hot tearing in DC casting. The test apparatus has two cast bars, one that is used to measure the load response and one which is fixed at both ends to restrain thermal contraction so that hot tearing can be observed and rated where it occurred. The iron (Fe) content, ranging from 0.02 to 0.5 wt pct, was seen to have a major influence on the load response during solidification and the tear rating of these alloys. The findings are discussed in terms of Rappaz-Drezet-Gremaud (RDG) model sensitivity analysis and related to the effect of Fe content on the morphology and prevalence of the β-Al₅FeSi and α-AlFeSi intermetallic phases and their influence on the coherency and coalescence of the microstructure.     

The relationship between cognitive performance,perceptions of driving comfort and abilities,and self-reported driving restrictions among healthy older drivers

The objective of the present study was to examine the relationship between cognitive performance, driver perceptions and self-reported driving restrictions. A cross-sectional analysis was conducted on baseline data from Candrive II, a five-year prospective cohort study of 928 older drivers aged 70–94 years from seven cities. Cognitive performance was assessed using the Montreal Cognitive Assessment (MoCA) as well as the Trail Making Test, parts A and B. Driver perceptions were assessed using the Day and Night Driving Comfort Scales and the Perceived Driving Abilities scale, while driving practices were captured by the Situational Driving Frequency and Avoidance scales, as well as the Driving Habits and Intentions Questionnaire. The baseline data indicates this cohort is largely a cognitively intact group. Univariate regression analysis showed that longer Trails A and B completion times were significantly, but only modestly associated with reduced driving frequency and perceived driving abilities and comfort, as well as a significant tendency to avoid more difficult driving situations (all p < .05). Most of these associations persisted after adjusting for age and sex, as well as indicators of health, vision, mood and physical functioning. Exceptions were Trails A and B completion times and situational driving frequency, as well as time to complete Trails B and current driving restrictions. After adjusting for the confounding factors, the total MoCA score was not associated with any of the driving measure scores while the number of errors on Trails A was significantly associated only with situational driving frequency and number of errors on Trails B was significantly associated only with situational driving avoidance. Prospective follow-up will permit examination of whether baseline cognition or changes in cognition are associated with changes in driver perceptions, actual driving restrictions and on-road driving outcomes (e.g., crashes, violations) over time.     

Effect of Alloy Composition on the Dendrite Arm Spacing of Multicomponent Aluminum Alloys

Predictions of secondary dendrite arm spacing (SDAS) for multicomponent aluminum alloys using a dendrite ripening model are compared with experimental observations. For six of the seven alloys studied, the predicted SDAS was within 20 pct of the measured SDAS. It was found that the final SDAS was dependent upon both the solidification time and the solute profile of the solidifying alloys. It is interesting that while the solidification times and the solute segregation during solidification varied significantly over the range of alloys, these two factors largely canceled each other out so that the predicted SDAS did not vary much between the alloys. The experimental and modeling results show that elements causing high constitutional undercooling near the beginning of solidification, e.g., Ti, which reduces the grain size substantially, have little effect on the SDAS. Instead, it was found that elements that strongly partitioned toward the end of solidification were more effective at restricting SDAS coarsening.     

Evaluation of Railroad Wheel Steel with Lamellar Duplex Microstructures Using Diffuse Ultrasonic Backscatter

The effects of lamellar duplex microstructure within grains that contain alternating phases of cementite and ferrite on ultrasonic scattering in railroad wheel steel are evaluated using a diffuse ultrasonic backscatter technique. A new singly scattered response (SSR) model that considers the lamellar duplex microstructure within grains is developed based on a previous SSR model. The results show that the amplitude of ultrasonic scattering decreases with decreasing lamellar space. Corresponding experiments are performed with 10 MHz and 15 MHz focused transducers by scanning both unquenched and quenched wheels. The experimental results show that the ultrasonic scattering amplitudes drop dramatically near the quenched tread surface, a result which is attributed to the creation of duplex microstructure (pearlite phase) within grains due to the quenching process. The lamellar spacing within grains increases progressively from the tread surface to the deeper locations due to the non-uniform cooling rate. The distribution of lamellar spacing within grains as a function of depth is quantified with the modified SSR model. Good agreement with optical microscopy is observed. The diffuse ultrasonic backscatter technique exhibits strong sensitivity to microstructure changes, an outcome that may be applicable for quality control during manufacturing.