Integral Equation Method for Evaluation of Eddy-Current Impedance of a Rectangular,Near Surface Crack Inside a Cylindrical Hole

An integral equation method for solving the eddy-current nondestructive evaluation problem of a flat, rectangular, near surface crack inside of a cylindrical hole in a conducting material is presented. The method involves expanding the Green’s tensor, the incoming field, and the jump in electric potential over the crack in suitable basis functions. Here, plane waves, cylindrical waves, and basis functions related to the Chebyshev polynomials, are used. The way of discretization in this method leads to a formulation where the scattering is defined by a scattering matrix, independent of the incoming field. This presents an advantage, when conducting numerical simulations, since the scattering matrix does not have to be recalculated for every probe position. The numerical calculations are straightforward to perform and model predictions are compared with finite element results.     

A naturalistic study of commuter cyclists in the greater Stockholm area

Few naturalistic studies have been carried out with commuter cyclists to discover the types of problems they encounter on a daily basis. The study presented here has been commissioned by the City of Stockholm municipality and focuses specifically on commuter cyclists in the Greater Stockholm area. The aim of the study was to describe and pinpoint accessibility and safety problems, but also to generate an accessible geographical interface that could serve as a traffic planning tool for cycle network improvement. Statistical surveys in the Stockholm area have shown a rapid growth in the number of cyclists as well as an increase in problems associated with an overburdened cycle infrastructure. Given the heightened emphasis on transport system sustainability, the City of Stockholm is faced with the challenging task of trying to maintain and encourage the upward trend in commuter cycling through a process that involves problem identification, classification, prioritisation and resolution. An innovative methodology involving the use of GPS logging devices and small video cameras was developed and supported with analysis software designed specifically for the purposes of this study. Experienced commuter cyclists were recruited to cycle 17 different major cycle routes to and from the suburbs and inner city area during morning and afternoon peak traffic hours during the main cycle season. Over 500 safety and accessibility/mobility problems were identified and recorded from the data collected from 16 commuter cyclists. The method and representation of data proved successful for strategic traffic planning work at City of Stockholm and has since provided invaluable input for and the development of a new cycle plan for Greater Stockholm. Indirectly, the results of this work have also contributed to longer term safety and environmental targets.     

Muscle decomposition and recruitment criteria influence muscle force estimates

It has recently been pointed out that muscle decomposition influence muscle force estimates in musculoskeletal simulations. We show analytically and with numerical simulations that this influence depends on the recruitment criteria. Moreover, we also show that the proper choices of force normalization factors may overcome the issue. Such factors for the minmax and the polynomial criteria are presented.     

Ilmenite with addition of NiO as oxygen carrier for chemical-looping combustion

The naturally occurring mineral ilmenite, FeTiO₃, has been examined as oxygen carrier for chemical-looping combustion. NiO-based particles have been used as an additive, in order to examine if it is possible to utilize the catalytic properties of metallic Ni to facilitate decomposition of hydrocarbons into more reactive combustion intermediates such as CO and H₂. Firstly, ilmenite was examined by oxidation and reduction experiments in a batch fluidized-bed reactor. These experiments indicated moderate reactivity between ilmenite and CH₄, which was used as reducing gas. However, adding 5 wt.% of NiO-based particles to the ilmenite improved the conversion of CH₄ greatly, resulting in an increase in combustion efficiency with a factor of 3. Secondly, 83 h of chemical-looping combustion experiments were conducted in a small circulating fluidized-bed reactor, using ilmenite as oxygen carrier and natural gas as fuel. A wide range of process parameters and different levels of NiO addition were examined. Occasionally, there were problems with the circulation of solids between the air reactor and fuel reactor, but most of the time the experiments worked well. The products were mostly CO₂, H₂O and unconverted CH₄. Adding small amounts of NiO-based particles to the reactor increased the conversion of the fuel considerably. For the base case conducted at 900°, the combustion efficiency was 76% for pure ilmenite and 90% for the corresponding experiments with 1 wt.% NiO-based particles added to the reactor. The properties of ilmenite were found to change considerably during operation. Used particles had lower density, were more reactive and more porous than fresh particles. These changes appear to have been physical, and no unexpected chemical phases could be identified.     

Superior self-paced memorization of digits in spite of a normal digit span: The structure of a memorist’s skill.

Over the last century many individuals with exceptional memory have been studied and tested in the laboratory. This article studies Chao Lu, who set a Guinness World Record by memorizing 67,890 decimals of pi. Chao Lu’s superior self-paced memorization of digits is shown through analyses of study times and verbal reports to be mediated by mnemonic encoding and retrieval processes. Furthermore, Chao Lu’s development of his superior memory for decimals of pi is consistent with his engagement in thousands of hours of memorization. In contrast to most other studied memorists, who have digit spans over 15 digits, Chao Lu exhibited a digit span in only the normal range. Implications for different types of memorization skills and associated practice activities are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Computational Investigation of the Interaction of Pulses in Two-Pulse Jets

Large-eddy simulations (LES) and Reynolds-averaged Navier-Stokes (RANS) simulations of the interaction of the second pulse with the first pulse in a double-injection event are presented in this study. The opposing effects of the turbulence generated by the first pulse to accelerate mixing of the second pulse, and the residual bulk velocity from the first pulse to accelerate penetration of the second pulse are analyzed. The LES results show greater influence of the turbulence whereas the RANS results show greater influence of the bulk velocity.     

The nature of polymer grafts and substrate shape on the surface degradation of poly(l‐lactide)

Surface grafting of functional polymers is an effective method to alter material properties and degradation behavior. Two different substrate shapes of poly(l ‐lactide) (PLLA), i.e., films and microparticles, were surface‐grafted with hydrophilic monomers, and their surface degradation was monitored. Surface grafting with a hydrophilic and acidic polymer graft [acrylic acid (AA)] induced large alterations in the surface morphology and topography of the films. In contrast, hydrophilic and neutral polymer grafts [acrylamide (AAm)] had no significant effect on the surface degradation behavior, while the PLLA reference and co‐monomeric (AA/AAm) polymer‐grafted samples exhibited intermediate surface degradation rates. The grafted PAA chains induced a local acidic environment on the surface of the substrates, which in turn catalyzed the surface degradation process. This effect was more pronounced in the films than in the microparticles. Thus, the nature of the grafted chains and substrate geometry were shown to affect the surface degradation behavior of PLLA substrates. © 2015 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42736.     

Passive 350 GHz Video Imaging Systems for Security Applications

Journal of Infrared, Millimeter, and Terahertz Waves - Passive submillimeter-wave imaging is a concept that has been in the focus of interest as a promising technology for personal security...     

Associations between driving under the influence of alcohol or drugs,speeding and seatbelt use among fatally injured car drivers in Norway

Since 2005, all fatal road traffic crashes in Norway have been analyzed in-depth by multidisciplinary investigation teams organized by the Norwegian Public Roads Administration (NPRA). During the period 2005–2010, 608 drivers of cars or vans were killed in road traffic crashes. Blood samples were collected from 372 (61%) of the drivers and analyzed for alcohol and a large number of psychoactive drugs at the Norwegian Institute of Public Health (NIPH). After coupling the analytical results with the NPRA crash database, 369 drivers with a fatal outcome were identified and included. Alcohol or drug concentrations in blood above the legal limits were found in 39.8% of the drivers who were investigated for alcohol or drug impairment; 33.9% had blood alcohol concentrations above 0.5 g/L or concentrations of drugs above the equivalent Norwegian legal impairment limits or concentrations of amphetamines above 200 μg/L. Among drivers with a fatal outcome who had been impaired by alcohol or drugs, 64.6% were unbelted and 71.7% were speeding when the crash occurred; whereas 24.2% and 33.2% of the sober drivers were unbelted or speeding, respectively. Statistically significant associations were found between impairment by alcohol or amphetamines and driving unbelted or speeding. Excessive speeding is one of the main reasons for road traffic crashes and together with being unbelted the main reasons for a fatal outcome. This behavior might in many cases be due to increased risk-taking or negligence of safety measures as a result of alcohol or drug use.