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Measurement Campaign (measurement + campaign)

Distribution by Scientific Domains

Engineering	45%
Earth and Environmental Science	36%

Selected Abstracts

A large-scale monitoring and measurement campaign for web services-based applications

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 10 2010
Riadh Ben Halima
Abstract Web Services (WS) can be considered as the most influent enabling technology for the next generation of web applications. WS-based application providers will face challenging features related to nonfunctional properties in general and to performance and QoS in particular. Moreover, WS-based developers have to provide solutions to extend such applications with self-healing (SH) mechanisms as required for autonomic computing to face the complexity of interactions and to improve availability. Such solutions should be applicable when the components implementing SH mechanisms are deployed on both or only one platform on the WS providers and requesters sides depending on the deployment constraints. Associating application-specific performance requirements and monitoring-specific constraints will lead to complex configurations where fine tuning is needed to provide SH solutions. To contribute to enhancing the design and the assessment of such solutions for WS technology, we designed and implemented a monitoring and measurement framework, which is part of a larger Self-Healing Architectures (SHA) developed during the European WS-DIAMOND project. We implemented the Conference Management System (CMS), a real WS-based complex application. We achieved a large-scale experimentation campaign by deploying CMS on top of SHA on the French grid Grid5000. We experienced the problem as if we were a service provider who has to tune reconfiguration strategies. Our results are available on the web in a structured database for external use by the WS community. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Evaluation of electromagnetic interference on telecommunication cables from an AC railway line: Measurements and calculations

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2003
G. Lucca
The paper describes the main results of a field measurement campaign of the electromagnetic interference produced by a 25 kV - 50 Hz railway line on nearby telecommunication cables; the results of the measurements were compared with the results of calculations based on suitable circuit models for studying the inducing and induced systems. The results of the comparison were deemed satisfactory. [source]

A model computation of the temporal changes of surface gravity and geoidal signal induced by the evolving Greenland ice sheet

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2001
Emmanuel Le Meur
Summary This paper deals with present-day gravity changes in response to the evolving Greenland ice sheet. We present a detailed computation from a 3-D thermomechanical ice sheet model that is interactively coupled with a self-gravitating spherical viscoelastic bedrock model. The coupled model is run over the last two glacial cycles to yield the loading evolution over time. Based on both the ice sheet's long-term history and its modern evolution averaged over the last 200 years, results are presented of the absolute gravity trend that would arise from a ground survey and of the corresponding geoid rate of change a satellite would see from space. The main results yield ground absolute gravity trends of the order of ±1 µgal yr,1 over the ice-free areas and total geoid changes in the range between ,0.1 and +0.3 mm yr,1. These estimates could help to design future measurement campaigns by revealing areas of strong signal and/or specific patterns, although there are uncertainties associated with the parameters adopted for the Earth's rheology and aspects of the ice sheet model. Given the instrumental accuracy of a particular surveying method, these theoretical trends could also be useful to assess the required duration of a measurement campaign. According to our results, the present-day gravitational signal is dominated by the response to past loading changes rather than current mass changes of the Greenland ice sheet. We finally discuss the potential of inferring the present-day evolution of the Greenland ice sheet from the geoid rate of change measured by the future geodetic GRACE mission. We find that despite the anticipated high-quality data from satellites, such a method is compromised by the uncertainties in the earth model, the dominance of isostatic recovery on the current bedrock signal, and other inaccuracies inherent to the method itself. [source]

Different methods for modelling the areal infiltration of a grass field under heavy precipitation

HYDROLOGICAL PROCESSES, Issue 7 2002
Bruno Merz
Abstract The areal infiltration behaviour of a grass field is studied using a data set of 78 sprinkler infiltration experiments. The analysis of the experimental data shows a distinct event dependency: once runoff begins, the final infiltration rate increases with increasing rainfall intensity. This behaviour is attributed to the effects of small-scale variability. Increasing rainfall intensity increases the ponded area and therefore the portion of the plot which infiltrates at maximum rate. To describe the areal infiltration behaviour of the grass field the study uses two different model structures and investigates different approaches for consideration of subgrid variability. It is found that the effective parameter approach is not suited for this purpose. A good representation of the observed behaviour is obtained by using a distribution function approach or a parameterization approach. However, it is not clear how the parameters can be derived for these two approaches without a large measurement campaign. The data analysis and the simulations show the great importance of considering the effects of spatial variability for the infiltration process. This may be significant even at a small scale for a comparatively homogeneous area. The consideration of heterogeneity seems to be more important than the choice of the model type. Furthermore, similar results may be obtained with different modelling approaches. Even the relatively detailed data set does not seem to permit a clear model choice. In view of these results it is questionable to use very complex and detailed simulation models given the approximate nature of the problem. Although the principle processes may be well understood there is a lack of models that represent these processes and, more importantly, there is a lack of techniques to measure and parameterize them. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Practical performance of digital cellular system in mass rapid transit environments

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2005
Y. P. ZhangArticle first published online: 13 DEC 200
Abstract Leaky coaxial cables have found applications in the creation of network infrastructures for mobile and personal communication services in underground and enclosed spaces. A digital cellular system based on the GSM 900 standard and using radiated mode leaky coaxial cables has been implemented in an underground mass rapid transit environment. This paper presents the practical performance evaluation of the system. First, we start with a brief introduction of a radiated mode leaky coaxial cable and the digital cellular system GSM 900, and then we move into a full description of the measurement campaign; next we focus on an analysis of the measured performance data about received signal level, received signal quality, speech quality index and grade of service. The results show that the system performance is generally good; however, the poor system performance often occurs at the terminals of the leaky coaxial cable. In addition, it is found that the system performance is highly correlated with the density of train passenger. The higher train passenger density degrades the system performance. Copyright © 2004 John Wiley & Sons, Ltd. [source]

The COST 723 Action

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue S2 2007
W. A. Lahoz
Abstract An overview is provided of the COST 723 Action, ,Data Exploitation and Modelling of the Upper Troposphere and Lower Stratosphere'. The three working groups are introduced and a summary of Action activities within them is provided. The achievements of the Action are: three international workshops; the LAUTLOS humidity measurement campaign; dedicated meetings to discuss the quality of upper troposphere/lower stratosphere ozone and humidity measurements; two journal special issues; more than 90 papers in the peer-reviewed literature; one international summer school; and a successor COST Action which builds on COST 723. The recommendations made are: for COST to continue to support the short-term scientific missions instrument, as they are perceived to be value for money; to encourage the use of COST money to increase links between COST Actions and other scientific communities; and for the COST secretariat to recommend that Actions consider a summer school instead of a final workshop or meeting. Copyright © 2007 Royal Meteorological Society [source]

Topographic controls on spatial patterns of conifer transpiration and net primary productivity under climate warming in mountain ecosystems

ECOHYDROLOGY, Issue 4 2009
C. Tague
Abstract The response of forests to a warmer climate depends upon the direct impacts of temperature on forest ecophysiology and indirect effects related to a range of biogeophysical processes. In alpine regions, reduced snow accumulation and earlier melt of seasonal snowpacks are expected hydrologic consequences of warming. For forests, this leads to earlier soil moisture recharge, and may increase summer drought stress. At the same time, increased air temperature alters plant net primary productivity. Most models of climate change impacts focus either on hydrologic behaviour or ecosystem structure or function. In this study we address the interactions between them. We use a coupled model of eco-hydrologic processes to estimate changes in evapotranspiration and vegetation productivity under temperature warming scenarios. Results from Yosemite National Park, in the California Sierra Nevada, suggest that for most snow-dominated elevations, the shift in the timing of recharge is likely to lead to declines in productivity and vegetation water use, even with increased water-use efficiency associated with elevated atmospheric CO2 concentrations. The strength of this effect, however, depends upon interactions between several factors that vary substantially across elevation gradients, including the initial timing of melt relative to the summer growing season, vegetation growth, and the extent to which initial vegetation is water-limited or temperature-limited. These climate-driven changes in vegetation water use also have important implications for summer streamflow. Results from this analysis provide a framework that can be used to develop strategic measurement campaigns and to extrapolate from local measurements of vegetation responses to watershed scale patterns. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A model computation of the temporal changes of surface gravity and geoidal signal induced by the evolving Greenland ice sheet

End-to-end QoS and global mobility management in an integrated satellite/terrestrial network

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2004
P. Conforto
Abstract For decades, the development of the Internet was driven by the purpose of providing applications to non-mobile users. No specific Quality of Service (QoS) requirement is necessary, other than ensuring reliability in the end-to-end data transfers. As such, best effort service model was deemed more than appropriate to satisfy the users' needs. Nevertheless, the scenario has changed in the last few years. A new population of nomadic users, who requires access to Internet services regardless of their location and mode of transportation is growing, while new typologies of Internet applications are being continuously developed, in which best effort service level may no longer be adequate. The SUITED project has been devised to address the emerging issues generated by this new and challenging scenario. SUITED aims at contributing towards the design and deployment of the Global Mobile Broadband System (GMBS), a unique satellite/terrestrial infrastructure, which will ensure that nomadic users have access to Internet services with a negotiated QoS. An overview of the main results achieved in the SUITED project is provided in this article. Some of the most innovative solutions developed by the SUITED team for the joint management of global mobility and end-to-end QoS support are presented. The SUITED demonstrator platform, which was developed to validate the system specifications, is also described. Finally, the results of the experimental measurement campaigns carried out with this platform are reported. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Propagation considerations and fading countermeasures for mobile multimedia services

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2001
Axel Jahn
Abstract This paper presents a summary of land mobile satellite (LMS) channel characteristics derived from several measurement campaigns. Narrowband and wideband measurements allow a broad interpretation of the LMS channels. Channel models and its parameters have been derived from the measured data as well. Furthermore, the impact of the LMS channel on the communication service is investigated and possible countermeasures are discussed. Link margins, power control schemes and satellite diversity can compensate the fading on the transmission links. The benefit of adaptive receivers and the dependence on the signal bandwidth are investigated, too. Copyright © 2001 John Wiley & Sons, Ltd. [source]

PIN diamond detector development for LYRA, the solar VUV radiometer on board PROBA II

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2004
A. BenMoussa
Abstract LYRA (the LYman-alpha RAdiometer onboard PROBA-2) will use diamond detectors for the first time in space solar physics. A set of measurement campaigns was designed to obtain the EUV-to-VIS characterization of the diamond detectors and knowledge of their modes of operation. The outputs of this campaign provide the reference data needed for the optimization of the detectors, and for the LYRA channels definition. The measurements of responsivity in EUV and VUV spectral ranges have been carried out by the Physkalisch-Technische Bundesanstalt (PTB) in Germany at the electron storage ring BESSY II. The detectors spectral responsivity measurements R(,) was done for the following wavelength ranges: 40 to 80 nm, 80 to 120 nm and 120 to 240 nm. The longer wavelength range from 210 nm to 827 nm was measured with the monochromatic light by using a Xe-lamp at IMO-IMOMEC. The diodes exhibit high photoresponse in the deep UV region and over five orders of magnitude in discrimination between deep UV (200 nm) and visible light (550 nm). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]