586 research outputs found

    Technological agglomeration and the emergence of clusters and networks in nanotechnology

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    Research and development at the nanoscale requires a large degree of integration, from convergence of research disciplines in new fields of enquiry to new linkages between start-ups, regional actors and research facilities. Based on the analysis of two clusters in nanotechnologies (MESA+ (Twente) and other centres in The Netherlands and Minatec in Grenoble in France), the paper discusses the phenomenon of technological agglomeration: co-located scientific and technological fields associated to coordinated technology platforms to some extent actively shaped by institutional entrepreneurs. Such co-location and coordination are probably a prerequisite for the emergence of strong nanocluster

    The embedding of universities in innovation ecosystems: The case of marine research at the University of Bergen

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    While historically the core missions of universities have been research and teaching, it has become increasingly recognised that universities have become significant sources of knowledge and capabilities. This third mission is cementing the role of universities as suppliers of qualified labour and generators of knowledge and technologies that promote innovation in a variety of innovation ecosystems. The main goal of the paper is to illustrate an approach that captures the various contributions of universities to their innovation ecosystems. Often territorially bounded, such links provide insights into the characteristics and geography of the various linkage for a university. With the case of the University of Bergen and its role within the marine innovation ecosystem of Western Norway, this ‘ecosystem fingerprint’, can be seen as a useful means to clarify the third mission of universities through the linkages and interdependencies with various actors. The authors demonstrate that a university can act both as a global pipeline provider and take active part in the local buzz, providing this concept with new empirical insight. The authors conclude that the university is highly embedded in both the marine innovation ecosystem and the knowledge ecosystem, but with linkages extended to interconnected business ecosystems.publishedVersio

    Probability density function of turbulent velocity fluctuations in rough-wall boundary layer

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    The probability density function of single-point velocity fluctuations in turbulence is studied systematically using Fourier coefficients in the energy-containing range. In ideal turbulence where energy-containing motions are random and independent, the Fourier coefficients tend to Gaussian and independent of each other. Velocity fluctuations accordingly tend to Gaussian. However, if energy-containing motions are intermittent or contaminated with bounded-amplitude motions such as wavy wakes, the Fourier coefficients tend to non-Gaussian and dependent of each other. Velocity fluctuations accordingly tend to non-Gaussian. These situations are found in our experiment of a rough-wall boundary layer.Comment: 6 pages, to appear in Physical Review

    Comparative analysis of pedestrian injuries using police, emergency department, and death certificate data sources in North Carolina, U.S., 2007–2012

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    Pedestrian safety programs are needed to address the rising incidence of pedestrian fatalities. Unfortunately, most communities lack comprehensive information on the circumstances of pedestrian crashes and resulting injuries that could help guide decision-making for prevention program development and implementation. This study aimed to evaluate how three commonly available data sources (police-reported pedestrian crashes, emergency department [ED] visits, and death certificates) define and capture pedestrian injury data, and to compare the distribution of pedestrian injuries and fatalities across these data sources. Existing state-wide data sources in North Carolina, U.S.A.,—police-reported pedestrian crashes, ED visits, and death certificates—were used to perform a descriptive analysis of temporal and demographic pedestrian injury severity distributions for a 6-year period (2007–2012). After excluding non-relevant cases, there were 12,646 police-reported pedestrian crashes, 17,369 pedestrian-injury-related ED visits, and 993 pedestrian-related death certificate cases. Pedestrian injury distributions appeared similar across the three data sets in relation to pedestrian sex, age, and temporality. Police data (which represented crashes rather than all pedestrians involved in a crash) likely underrepresented pedestrian injury incidence, while ED data (which represented ED visits, with multiple visits per person possible) likely overrepresented pedestrian injury incidence. The study provides a better understanding of the discrepancies between pedestrian injury data sources and key considerations when using police, ED, and death certificate data for surveillance or injury prevention efforts

    Using MapMyFitness to place physical activity into neighborhood context

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    It is difficult to obtain detailed information on the context of physical activity at large geographic scales, such as the entire United States, as well as over long periods of time, such as over years. MapMyFitness is a suite of interactive tools for individuals to track theirworkouts online or using global positioning system in their phones or other wireless trackers. This method article discusses the use of physical activity data tracked using MapMyFitness to examine patterns over space and time. An overview of MapMyFitness, including data tracked, user information, and geographic scope, is explored. We illustrate the utility of MapMyFitness data using tracked physical activity by users in Winston-Salem, NC, USA between 2006 and 2013. Types of physical activities tracked are described, as well as the percent of activities occurring in parks. Strengths of MapMyFitness data include objective data collection, low participant burden, extensive geographic scale, and longitudinal series. Limitations include generalizability, behavioral change as the result of technology use, and potential ethical considerations. MapMyFitness is a powerful tool to investigate patterns of physical activity across large geographic and temporal scales

    Stress corrosion cracking in Al-Zn-Mg-Cu aluminum alloys in saline environments

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    Copyright 2013 ASM International. This paper was published in Metallurgical and Materials Transactions A, 44A(3), 1230 - 1253, and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack (“pop-in” vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies (E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (~0.8 wt pct), they are typically ranging from 20 to 40 kJ/mol for under- and peak-aged alloys, and based on limited data, around 85 kJ/mol for over-aged tempers. This means that crack propagation in saline environments is most likely to occur by a hydrogen-related process for low-copper-containing Al-Zn-Mg-Cu alloys in under-, peak- and over-aged tempers, and for high-copper alloys in under- and peak-aged tempers. For over-aged high-copper-containing alloys, cracking is most probably under anodic dissolution control. Future stress corrosion studies should focus on understanding the factors that control crack initiation, and insuring that the next generation of higher performance Al-Zn-Mg-Cu alloys has similar longer crack initiation times and crack propagation rates to those of the incumbent alloys in an over-aged condition where crack rates are less than 1 mm/month at a high stress intensity factor

    The design and performance of an improved target for MICE

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    The linear motor driving the target for the Muon Ionisation Cooling Experiment has been redesigned to improve its reliability and performance. A new coil-winding technique is described which produces better magnetic alignment and improves heat transport out of the windings. Improved field-mapping has allowed the more precise construction to be demonstrated, and an enhanced controller exploits the full features of the hardware, enabling increased acceleration and precision. The new user interface is described and analysis of performance data to monitor friction is shown to allow quality control of bearings and a measure of the ageing of targets during use
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