1000 resultados para Perturbation techniques
Resumo:
An investigation into customer loyalty to food retailers posed a methodological problem namely how to delve beneath the surface and access consumers' unspoken feelings, perceptions, attitudes and values. This paper explains how four different projective techniques were used to access the thoughts and feelings of 160 interviewees in order to obtain a thorough understanding of the interviewees' satisfaction with their 'main' food retailer and to characterize the relationship between the customer and retailer. A brief description of the use, analysis and examples of cartoon friends, word association, personification and mini case studies was provided in order to describe their role in the data collection process.
Resumo:
A research project in Web-enabled collaborative design and manufacture has been conducted. The major tasks of the project include the development of a Web-enabled environment for collaboration, online collaborative CAD/CAM, remote execution of large size programs (RELSP), and distributed product design. The tasks and Web/Internet techniques involved are presented first, followed by detail description of two approaches developed for implementation of the research: (1) a client-server approach for RELSP, where the following Internet techniques are utilized: CORBA, Microsoft’s Internet information server, Tomcat server, JDBC and ODBC; (2) Web-Services supported collaborative CAD which enables geographically dispersed designers jointly conduct a design task in the way of speaking and seeing each other and instantaneously modifying the CAD drawing online.
Resumo:
Power system islanding can improve the continuity of power supply. Synchronous islanded operation enables the islanded system to remain in phase with the main power system while not electrically connected, so avoiding out-of-synchronism re-closure. Specific consideration is required for the multiple-set scenario. In this paper a suitable island management system is proposed, with the emphasis being on maximum island flexibility by allowing passive islanding transitions to occur, facilitated by intelligent control. These transitions include: island detection, identification, fragmentation, merging and return-to-mains. It can be challenging to detect these transitions while maintaining syn-chronous islanded operation. The performance of this control system in the presence of a variable wind power in-feed is also examined. A Mathworks SimPowerSystems simulation is used to investigate the performance of the island management system. The benefit and requirements for energy storage, com-munications and distribution system protection for this application are considered.
Resumo:
Connectivity mapping is a recently developed technique for discovering the underlying connections between different biological states based on gene-expression similarities. The sscMap method has been shown to provide enhanced sensitivity in mapping meaningful connections leading to testable biological hypotheses and in identifying drug candidates with particular pharmacological and/or toxicological properties. Challenges remain, however, as to how to prioritise the large number of discovered connections in an unbiased manner such that the success rate of any following-up investigation can be maximised. We introduce a new concept, gene-signature perturbation, which aims to test whether an identified connection is stable enough against systematic minor changes (perturbation) to the gene-signature. We applied the perturbation method to three independent datasets obtained from the GEO database: acute myeloid leukemia (AML), cervical cancer, and breast cancer treated with letrozole. We demonstrate that the perturbation approach helps to identify meaningful biological connections which suggest the most relevant candidate drugs. In the case of AML, we found that the prevalent compounds were retinoic acids and PPAR activators. For cervical cancer, our results suggested that potential drugs are likely to involve the EGFR pathway; and with the breast cancer dataset, we identified candidates that are involved in prostaglandin inhibition. Thus the gene-signature perturbation approach added real values to the whole connectivity mapping process, allowing for increased specificity in the identification of possible therapeutic candidates.
Resumo:
A unitary operator V and a rank 2 operator R acting on a Hilbert space H are constructed such that V + R is hypercyclic. This answers affirmatively a question of Salas whether a finite rank perturbation of a hyponormal operator can be supercyclic.