Effect of machining parameters and cutting tool coating on hole quality in dry drilling of fibre metal laminates

Fibre metal laminates (FMLs) are a special type of hybrid materials, which consist of sheets of metallic alloys and prepregs of composite layers stacked together in an alternating sequence and bonded together either mechanically using micro hooks or thermally using adhesive epoxies. The present paper contributes to the current literature by studying the effects of three types of cutting tool coatings namely TiAlN, AlTiN/TiAlN and TiN on the surface roughness and burr formation of holes drilled in an FML commercially known as GLARE®. While the cutting tool geometry is fixed, the study is also conducted for a range of drilling conditions by varying the spindle speed and the feed rate. The obtained results indicate that the spindle speed and the type of cutting tool coating had the most significant influence on the achieved surface roughness metrics, while tool coating had the most significant effect on burr height and burr root thickness. The most important outcome for practitioners is that the best results in terms of minimum roughness and burr formation were obtained for the TiN coated drills. However, such drills outperform the other two types of tools, i.e. with TiAlN and AlTiN/TiAlN coatings, only when used for short series of hole drilling due to rapid tool deterioratio

Monitoring the drilling process of carbon fibre laminates using acoustic emission

This work aims to apply Acoustic Emission to monitor the drilling process in carbon fibre laminates. Continuous Acoustic Emission data is captured over the entire drilling process of a through hole. The use of continuous acoustic emission data acquisition allows the identification of lower frequency periodic temporal features related to the cutting process. A new approach to data analysis is presented that utilises an enveloping technique to study these periodic phenomena and show that they correlate to changes in cutting regime as tool wear advances and hole quality reduces. This analysis of Acoustic Emission data is supported by the measurement of tool temperature, thrust force and the assessment of hole quality. Results show that Acoustic Emission activity is correlated to changes in the cutting process, and a correlation between tool wear and Acoustic Emission is observed. This correlation has been confirmed by corresponding increases in thrust force and drill temperature, with a consequent decrease in the observed hole quality

The development, design and characterisation of a scale model horizontal axis tidal turbine for dynamic load quantification

The paper describes the development and characterisation of three 0.9 m diameter lab-scale Horizontal Axis Tidal Turbines. The blade development process has been outlined and was used to generate a design specification. Each turbine houses instrumentation to measure rotor thrust, torque and blade root bending moments on each blade, in both `flapwise' and `edgewise' directions. A permanent magnet synchronous machine and encoder are integrated to allow for servo-control of the turbine as well as to provide position and rotational velocity measurements, resulting in three turbines that can be individually controlled using speed or torque control. Analogue signals are captured via a real-time operating system and field programmable gate array hardware architecture facilitating sample rates of up to 2 kHz. Results from testing the pilot turbine at three differing facilities during the development process are presented. Here good agreement, less than 7% variation, was found when comparing the testing undertaken at various flume and tow tank facilities. Lastly, the findings of a test campaign to characterise the performance of each of the three turbines are presented. Very good agreement in non-dimensional values for each of the three manufactured turbines was found

Lubrication regime of the contact between fat and bone in bovine tissue

Fat pads are masses of encapsulated adipose tissue located throughout the human body. Whilst a number of studies describe these soft tissues anatomically little is known about their biomechanics, and surgeons may excise them arthroscopically if they hinder visual inspection of the joint or bursa. By measuring the coefficient of friction between, and performing Sommerfeld analysis of, the surfaces approximating the in vivo conjuncture, this contact has been shown to have a coefficient of friction of the order of 0.01. The system appears to be lubricated hydrodynamically, thus possibly promoting low levels of wear. It is suggested that one of the functions of fat pads associated with subtendinous bursae and synovial joints is to generate a hydrodynamic lubricating layer between the opposing surfaces

Measurement Properties of Questionnaires Assessing Complementary and Alternative Medicine Use in Pediatrics: A Systematic Review

Complementary and alternative medicine (CAM) is commonly used by children, but estimates of that use vary widely partly due to the range of questionnaires used to assess CAM use. However, no studies have attempted to appraise measurement properties of these questionnaires. The aim of this systematic review was to critically appraise and summarize measurement properties of questionnaires of CAM use in pediatrics.A search strategy was implemented in major electronic databases in March 2011 and conference websites, scientific journals and experts were consulted. Studies were included if they mentioned a questionnaire assessing the prevalence of CAM use in pediatrics. Members of the team independently rated the methodological quality of the studies (using the COSMIN checklist) and measurement properties of the questionnaires (using the Terwee and Cohen criteria).A total of 96 CAM questionnaires were found in 104 publications. The COSMIN checklist showed that no studies reported adequate methodological quality. The Terwee criteria showed that all included CAM questionnaires had indeterminate measurement properties. According to the Cohen score, none were considered to be a well-established assessment, two approached the level of a well-established assessment, seven were promising assessments and the remainder (n = 87) did not reach the score's minimum standards.None of the identified CAM questionnaires have been thoroughly validated. This systematic review highlights the need for proper validation of CAM questionnaires in pediatrics, which may in turn lead to improved research and knowledge translation about CAM in clinical practice

Effects of Elevated Temperature and Carbon Dioxide on the Growth and Survival of Larvae and Juveniles of Three Species of Northwest Atlantic Bivalves

Rising CO2 concentrations and water temperatures this century are likely to have transformative effects on many coastal marine organisms. Here, we compared the responses of two life history stages (larval, juvenile) of three species of calcifying bivalves (Mercenaria mercenaria, Crassostrea virginica, and Argopecten irradians) to temperatures (24 and 28°C) and CO2 concentrations (∼250, 390, and 750 ppm) representative of past, present, and future summer conditions in temperate estuaries. Results demonstrated that increases in temperature and CO2 each significantly depressed survival, development, growth, and lipid synthesis of M. mercenaria and A. irradians larvae and that the effects were additive. Juvenile M. mercenaria and A. irradians were negatively impacted by higher temperatures while C. virginica juveniles were not. C. virginica and A. irradians juveniles were negatively affected by higher CO2 concentrations, while M. mercenaria was not. Larvae were substantially more vulnerable to elevated CO2 than juvenile stages. These findings suggest that current and future increases in temperature and CO2 are likely to have negative consequences for coastal bivalve populations

Myocardial Blood Flow Reserve Is Impaired in Patients With Aortic Valve Calcification and Unobstructed Epicardial Coronary Arteries

Background: Although calcific aortic valve disease (CAVD) is associated with coronary atherosclerosis, it is not known whether early CAVD is associated with coronary microcirculatory dysfunction (CMD). We sought to investigate the relationship between myocardial blood flow reserve (MBFR) - a measure of CMD, and early CAVD. We also determined whether this relationship was independent of coronary artery disease (CAD) and hs-CRP, a marker of systemic inflammation. Methods: 183 patients with chest pain and unobstructed coronary arteries were studied. Aortic valve calcification score (AVCS), coronary total plaque length (TPL), and coronary calcium score were quantified from multislice CT. MBFR was assessed using vasodilator myocardial contrast echocardiography. Hs-CRP was measured from venous blood using a particle-enhanced immunoassay. Results: Mean(±SD) participant age was 59.8(9.6) years. Mean AVCS was 68(258) AU, TPL was 15.6(22.2) mm, and median coronary calcification score was 43.5AU. Mean MBFR was 2.20(0.52). Mean hs-CRP was 2.52(3.86) mg/L. Multivariable linear regression modelling incorporating demographics, coronary plaque characteristics, MBFR, and inflammatory markers, demonstrated that age (β=0.05, 95%CI:0.02,0.08, P=0.007), hs-CRP (β=0.09, CI:0.02,0.16, P=0.010) and diabetes (β=1.03, CI:0.08,1.98, P=0.033), were positively associated with AVCS. MBFR (β=-0.87, CI:-1.44,-0.30, P=0.003), BMI (β=-0.11, CI:-0.21,-0.01, P=0.033), and LDL (β=-0.32, CI:-0.61,-0.03, P=0.029) were negatively associated with AVCS. TPL and coronary calcium score were not independently associated with AVCS when included in the regression model. Conclusion: Coronary microvascular function as determined by measurement of myocardial blood flow reserve is an independent predictor of early CAVD. This effect is independent of the presence of coronary artery disease and also systemic inflammation