Search results for "Testing"
showing 10 items of 1769 documents
Exploiting the optical quadratic nonlinearity of zinc-blende semiconductors for guided-wave terahertz generation: A material comparison
2010
We present a detailed analysis and comparison of dielectric waveguides made of CdTe, GaP, GaAs and InP for modal phase matched optical difference frequency generation (DFG) in the terahertz domain. From the form of the DFG equations, we derived the definition of a very general figure of merit (FOM). In turn, this FOM enabled us to compare different configurations, by taking into account linear and nonlinear susceptibility dispersion, terahertz absorption, and a rigorous evaluation of the waveguide modes properties. The most efficient waveguides found with this procedure are predicted to approach the quantum efficiency limit with input optical power in the order of kWs.
Epidemiological analysis of Salmonella enterica from beef sampled in the slaughterhouse and retailers in Dakar (Senegal) using pulsed-field gel elect…
2007
Seventy-eight isolates of Salmonella spp. isolated from beef sampled from the official city slaughterhouse and from retailers in Dakar, Senegal were analyzed using serotyping, antimicrobial testing and macrorestriction profiling by Pulsed-Field Gel Electrophoresis (PFGE). These analyses were done to identify clonal relationships and potential transmission routes in beef channel. XbaI macrorestriction allowed defining 17 genotypes among the six main analyzed serotypes: Salmonella bredeney (3 genotypes), S. muenster (6), S. waycross (1), S. corvallis (3), S. kentucky (1) and S. brandenburg (3). The cross analysis of PFGE profiles and origin of the beef samples reveals a wide range of contamin…
A Cloud Federation Architecture
2015
Cloud Computing is the state of the art computation paradigm enabling providers to offer computing resources to customers in a pay-per-use fashion. Nowadays public Cloud providers offer similar services within few service models, mainly IaaS and PaaS. Cloud providers give to the user the feeling to dispose of infinite resources, thus having to predict the user requirements in order to provide services with minimal costs, maintaining at the same time high levels of SLAs. In order to achieve this goal, Cloud providers can cooperate together to bring new business opportunities, such as expanding available resources, achieving cost effective asset optimization and adopting power saving policies…
Stochastic Fatigue Models for Efficient Planning Inspections in Service of Aircraft Structures
2008
For important fatigue-sensitive structures of aircraft whose breakdowns cause serious accidents, it is required to keep their reliability extremely high. In this paper, we discuss inspection strategies for such important structures against fatigue failure. The focus is on the case when there are fatiguecracks unexpectedly detected in a fleet of aircraft within a warranty period (prior to the first inspection). The paper examines this case and proposes stochastic models for prediction of fatigue-crack growth to determine appropriate inspections intervals. We also do not assume known parameters of the underlying distributions, and the estimation of that is incorporated into the analysis and d…
MonPaaS: An Adaptive Monitoring Platformas a Service for Cloud Computing Infrastructures and Services
2015
This paper presents a novel monitoring architecture addressed to the cloud provider and the cloud consumers. This architecture offers a monitoring platform-as-a-Service to each cloud consumer that allows to customize the monitoring metrics. The cloud provider sees a complete overview of the infrastructure whereas the cloud consumer sees automatically her cloud resources and can define other resources or services to be monitored. This is accomplished by means of an adaptive distributed monitoring architecture automatically deployed in the cloud infrastructure. This architecture has been implemented and released under GPL license to the community as “MonPaaS”, open source software for integra…
Which Test Artifacts Testing Service Providers should Reuse and How? Experiences from a Case Study in the Chinese ICT Sourcing Market
2011
Software testing service providers are facing new requirements to shorten service times, lower costs, and increase service customization and quality. Reuse of test artifacts is a possible solution that can help providers to meet the requirements because reuse can improve software quality and productivity. However, the extant literature does not explain in depth which test artifacts should be reused and how. This paper focuses on ICT-enabled sourcing of software testing services in the Chinese market to identify the most important reusable test artifacts. There are two reasons for this research. First, most Chinese service providers are small or medium-sized and have to overcome obstacles su…
Effect of the construction process on the performances of asphalt paving mixes with crumb rubber from scrap tires
2004
This paper presents the results of an experimental study on the use of CRM (Crumb Rubber Modifier) in bituminous mixtures for asphalt pavements, using a Dry Process. Employing experimental methods capable of ensuring that the mixtures obtained and the stress conditions that they undergo in pavements are representative, we clarify some aspects relating to the design and production of mixtures; we also show the effects of the bitumen-rubber interaction on mechanical performances (fatigue resistance and rutting). Among the various factors involved in manufacture, a particular investigation was carried out on the effects of asphalt content, mixing temperatures and mixture compaction. The experi…
1D Compression Behaviour of Opalinus Clay
2017
One of the main concerns related to tunnel excavations, drilling operations and wellbore stability in shales is the generation of excess pore water pressure due to changes in mechanical stress; therefore the consolidation of shales is a fundamental process that must be considered. This paper presents a compre- hensive methodology for analysing the compression and consolidation behaviour of shales. An apparatus to perform high-pressure oedometric tests is presented and an analytical method is introduced to analyse the shale consolidation behaviour, which allows information to be gathered on the coeffi cient of consolidation, stiffness, poroelastic properties, and permeability of the tested m…
Assessment of bonding defects in FRP reinforced structures via ultrasonic technique
2016
Fiber reinforced polymer (FRP) composite systems are widely used for the rehabilitation of concrete structures such as building that need to resist to seismic loads, bridges that have to carry heavier traffic loads. The technique consists in bonding the composite plate to the concrete surface element in order to increase the flexural capacity. A proper attachment of the FRP plate to the concrete surface is necessary for the efficiency of the load transfer between the reinforcement and the substrate. In this work, the quality of composite bonding is characterized through ultrasonic testing. The proposed technique is relative to a time domain analysis of the ultrasonic signals and couples the…
FRP-Substrate bonding quality investigation making use of ultrasonic waves
2016
Fiber reinforced polymer (FRP) composite systems are widely used to repair structurally deficient constructions thanks to their good immunity to corrosion, low weight and excellent mechanical properties. The quality of the FRP-substrate interface bond is a crucial parameter affecting the performance of retrofitted structures. In this framework, ultrasonic testing could be used to assess the quality of the bonding [1-2]. In the case of FRP laminates adhesively bonded to roughly inhomogeneous materials, such as concrete, high scattering attenuation occurs due to the presence of heterogeneities. The concrete behaves almost like a perfect absorber generating a considerable number of short-space…