995 resultados para IF steel


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2.241 JCR (2015) Q3, 140/213 Oncology, 45/80 Nutrition & dietetics

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University of California Libraries

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It is well documented that the presence of even a few air bubbles in water can signifi- cantly alter the propagation and scattering of sound. Air bubbles are both naturally and artificially generated in all marine environments, especially near the sea surface. The abil- ity to measure the acoustic propagation parameters of bubbly liquids in situ has long been a goal of the underwater acoustics community. One promising solution is a submersible, thick-walled, liquid-filled impedance tube. Recent water-filled impedance tube work was successful at characterizing low void fraction bubbly liquids in the laboratory [1]. This work details the modifications made to the existing impedance tube design to allow for submersed deployment in a controlled environment, such as a large tank or a test pond. As well as being submersible, the useable frequency range of the device is increased from 5 - 9 kHz to 1 - 16 kHz and it does not require any form of calibration. The opening of the new impedance tube is fitted with a large stainless steel flange to better define the boundary condition on the plane of the tube opening. The new device was validated against the classic theoretical result for the complex reflection coefficient of a tube opening fitted with an infinite flange. The complex reflection coefficient was then measured with a bubbly liquid (order 250 micron radius and 0.1 - 0.5 % void fraction) outside the tube opening. Results from the bubbly liquid experiments were inconsistent with flanged tube theory using current bubbly liquid models. The results were more closely matched to unflanged tube theory, suggesting that the high attenuation and phase speeds in the bubbly liquid made the tube opening appear as if it were radiating into free space.

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OBJECTIVE: This study examined the impact of smoking, quitting, and time since quit on absences from work. METHODS: Data from the nationally representative Tobacco Use Supplements of the 1992/93, 1995/96, and 1998/99 Current Population Surveys were used. The study included full time workers aged between 18-64 years, yielding a sample size of 383 778 workers. A binary indicator of absence due to sickness in the last week was analysed as a function of smoking status including time since quit for former smokers. Extensive demographic variables were included as controls in all models. RESULTS: In initial comparisons between current and former smokers, smoking increased absences, but quitting did not reduce them. However, when length of time since quit was examined, it was discovered that those who quit within the last year, and especially the last three months, had a much greater probability of absences than did current smokers. As the time since quitting increased, absences returned to a rate somewhere between that of never and current smokers. Interactions between health and smoking status significantly improved the fit of the model. CONCLUSIONS: Smokers who quit reduced their absences over time but increase their absences immediately after quitting. Quitting ill may account for some but not all of this short run impact.

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Particle concentration is known as a main factor that affects erosion rate of pipe bends in pneumatic conveyors. With consideration of different bend radii, the effect of particle concentration on weight loss of mild steel bends has been investigated in an industrial scale test rig. Experimental results show that there was a significant reduction of the specific erosion rate for high particle concentrations. This reduction was considered to be as a result of the shielding effect during the particle impacts. An empirical model is given. Also a theoretical study of scaling on the shielding effect, and comparisons with some existing models, are presented. It is found that the reduction in specific erosion rate (relative to particle concentration) has a stronger relationship in conveying pipelines than has been found in the erosion tester.

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Considers the circumstances in which repair works may be more appropriate than replacement where a landlord is attempting to claim under a repair covenant. Examines case law on which method is more appropriate and on the standard of remedial work to be undertaken. Reflects on the situation where performance of remedial works would be futile. Comments on the Technology and Construction Court ruling in Carmel Southend Ltd v Strachan & Henshaw Ltd on whether a landlord had been correct to carry out overcladding works to a roof where surveyors had agreed that patch repairs would be adequate.

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The numeracy skill of student is a continued concern with numeracy highlighted as a key skill in Foundation degrees and other vocational courses such as nursing (DfES 1999, NMC 2007). Numeracy is seen as a requirement to being able to undertake work based skills that require the use of numbers and calculations. However numeracy skills developed in the classroom does not necessarily prepare students for work-based calculations and similarly nor does poor numeracy skills necessarily mean that students cannot perform complex mathematical calculations in their work place. This paper will explore the role of context, the difference between formal and work based mathematics and questions the continued focus on numeracy skills, using examples from my own research with nurses.

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This article is concerned with the remedies available for delay in the performance of contractual obligations, and in particular with the proper analysis of the question whether time is of the essence. The law in this area is both difficult and complex, not only with regard to whether time is of the essence in any given case, but also with regard to what this entails. It is argued that many of the difficulties arise from the ambiguous and inconsistent way in which the courts have approached the question whether time is of the essence, the concept being used in several distinct, albeit related, senses. The article seeks to demonstrate that the law relating to the topic is unnecessarily complicated, and to suggest ways in which it might be simplified.