The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Peter L. Knight - One of the best experts on this subject based on the ideXlab platform.
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Sampling entropies and Operational Phase-space measurement. II. Detection of quantum coherences
Physical review. A Atomic molecular and optical physics, 1995Co-Authors: Vladimir Buzek, Christoph H. Keitel, Peter L. KnightAbstract:We use the Operational Phase-space distributions and sampling entropies developed in the preceding paper [V. Bu\ifmmode \check{z}\else \v{z}\fi{}ek, C. H. Keitel, and P. L. Knight, Phys. Rev. A 51, 2575 (1995)] to discuss the nature of quantum interference between components of superpositions of states. We show how the Wehrl entropy, a special case of the sampling entropy, is a useful discriminator between different kinds of superpositions and of statistical mixtures, and is determined essentially by the coherent-state content. Apart from interference terms, this content is given by the quantum uncertainty of a single coherent state and the classical contribution to the number of coherent states necessary to tile the dominant Phase-space ``patch'' representing the quantum state of interest. We illustrate these ideas using nonclassical superpositions of coherent states, where interference modifies the Phase-space distributions, and show how these features are sensitive to dissipation.
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Sampling entropies and Operational Phase-space measurement. I. General formalism
Physical review. A Atomic molecular and optical physics, 1995Co-Authors: Vladimir Buzek, Christoph H. Keitel, Peter L. KnightAbstract:We present an entropic description of quantum-mechanical states based on an Operational approach to a Phase-space measurement. We give a simple Phase-space interpretation of sampling entropies in terms of which we derive very general entropic uncertainty relations reflecting the degree of the Phase-space uncertainty of the quantum-mechanical state in the given measurement (i.e., for a given ``quantum-ruler'' state). We relate the sampling entropy to the von Neumann and Shannon entropy and show that the Wehrl entropy represents a particular example of a sampling entropy when the quantum ruler is represented by coherent states.
Hong-yi Fan - One of the best experts on this subject based on the ideXlab platform.
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On Mutual Transform Between Number-Difference State and Phase State Corresponding to Operational Phase Operator*
Communications in Theoretical Physics, 2005Co-Authors: Hong-yi FanAbstract:In the mutual transform between the number-difference state and the Phase state corresponding to the Operational Phase operator we find that there exists an end-point ambiguousness. This problem can be avoided by Lighthill's method.
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Characteristic and Wigner function for number difference and Operational Phase
Journal of Optics B: Quantum and Semiclassical Optics, 2004Co-Authors: Hong-yi FanAbstract:We introduce the characteristic function in the sense of number difference–Operational Phase, and we employ the correlated-amplitude–number-difference state representation to calculate it. It results in the form of the corresponding Wigner function and Wigner operator. The marginal distributions of the generalized Wigner function are briefly discussed.
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Time evolution of the number-Operational Phase entangled state in a number-Phase entangled Jaynes-Cummings model
Journal of Physics A: Mathematical and General, 2003Co-Authors: Hong-yi FanAbstract:We apply the newly derived number-Operational Phase entangled state to solve a number-Phase entangled Jaynes–Cummings model. The time evolution of the Phase and number difference is calculated. The model also exhibits some collapse-revival phenomena.
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A NEW GENERALIZED JAYNES–CUMMINGS MODEL BASED ON TWO-MODE PHOTON NUMBER-DIFFERENCE AND Operational Phase
Modern Physics Letters B, 2003Co-Authors: Hong-yi FanAbstract:A new generalized Jaynes–Cummings model based on two-mode photon number-difference and Operational Phase is presented. The excitation of the atom is proportional to the net variation of the competion of two modes of photons in some nonlinear process. The corresponding Hamiltonian is diagonalized by virtue of the supersymmetric transform.
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A New Generalized Jaynes-Cummings Model Based on Two-Mode Photon Number-Difference and Operational Phase
Modern Physics Letters B, 2003Co-Authors: Hong-yi FanAbstract:A new generalized Jaynes–Cummings model based on two-mode photon number-difference and Operational Phase is presented. The excitation of the atom is proportional to the net variation of the competion of two modes of photons in some nonlinear process. The corresponding Hamiltonian is diagonalized by virtue of the supersymmetric transform.
Vladimir Buzek - One of the best experts on this subject based on the ideXlab platform.
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Sampling entropies and Operational Phase-space measurement. II. Detection of quantum coherences
Physical review. A Atomic molecular and optical physics, 1995Co-Authors: Vladimir Buzek, Christoph H. Keitel, Peter L. KnightAbstract:We use the Operational Phase-space distributions and sampling entropies developed in the preceding paper [V. Bu\ifmmode \check{z}\else \v{z}\fi{}ek, C. H. Keitel, and P. L. Knight, Phys. Rev. A 51, 2575 (1995)] to discuss the nature of quantum interference between components of superpositions of states. We show how the Wehrl entropy, a special case of the sampling entropy, is a useful discriminator between different kinds of superpositions and of statistical mixtures, and is determined essentially by the coherent-state content. Apart from interference terms, this content is given by the quantum uncertainty of a single coherent state and the classical contribution to the number of coherent states necessary to tile the dominant Phase-space ``patch'' representing the quantum state of interest. We illustrate these ideas using nonclassical superpositions of coherent states, where interference modifies the Phase-space distributions, and show how these features are sensitive to dissipation.
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Sampling entropies and Operational Phase-space measurement. I. General formalism
Physical review. A Atomic molecular and optical physics, 1995Co-Authors: Vladimir Buzek, Christoph H. Keitel, Peter L. KnightAbstract:We present an entropic description of quantum-mechanical states based on an Operational approach to a Phase-space measurement. We give a simple Phase-space interpretation of sampling entropies in terms of which we derive very general entropic uncertainty relations reflecting the degree of the Phase-space uncertainty of the quantum-mechanical state in the given measurement (i.e., for a given ``quantum-ruler'' state). We relate the sampling entropy to the von Neumann and Shannon entropy and show that the Wehrl entropy represents a particular example of a sampling entropy when the quantum ruler is represented by coherent states.
Marvin Rausand - One of the best experts on this subject based on the ideXlab platform.
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Monitoring human and organizational factors influencing common-cause failures of safety-instrumented system during the Operational Phase
Reliability Engineering & System Safety, 2013Co-Authors: Maryam Rahimi, Marvin RausandAbstract:Abstract Safety-instrumented systems (SISs) are important safety barriers in many technical systems in the process industry. Reliability requirements for SISs are specified as a safety integrity level (SIL) with reference to the standard IEC 61508. The SIS reliability is often threatened by common-cause failures (CCFs), and the beta-factor model is the most commonly used model for incorporating the effects of CCFs. In the design Phase, the beta-factor, β , is determined by answering a set of questions that is given in part 6 of IEC 61508. During the Operational Phase, there are several factors that influence β , such that the actual β differs from what was predicted in the design Phase, and therefore the required reliability may not be maintained. Among the factors influencing β in the Operational Phase are human and organizational factors (HOFs). A number of studies within industries that require highly reliable products have shown that HOFs have significant influence on CCFs and therefore on β in the Operational Phase, but this has been neglected in the process industry. HOFs are difficult to predict, and susceptible to be changed during the Operational Phase. Without proper management, changing HOFs may cause the SIS reliability to drift out of its required value. The aim of this article is to highlight the importance of HOFs in estimation of β for SISs, and also to propose a framework to follow the HOFs effects and to manage them such that the reliability requirement can be maintained.
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Advances in Safety, Reliability and Risk Management: ESREL 2011 - Management of factors that influence common cause failures of safety instrumented system in the Operational Phase
Advances in Safety Reliability and Risk Management, 2011Co-Authors: M.. Rahimi, Marvin Rausand, M LundteigenAbstract:This PhD thesis proposes new frameworks and methods which give new insights to qualification and reliability assessments of new subsea systems. The subsea oil and gas industry is an industry with strict requirements to the reliability of their equipment. The provision of new subsea technology with an acceptable level of reliability is a prerequisite to achieve high production availability, low maintenance costs and less consequences such as oil spills to the environment or other types of accidents.Before a new technology or a new system is accepted for use, the equipment supplier must convince the operator that the reliability of the new technology/ system is sufficiently high. This may be accomplished through a technology qualification program (TQP).The objective of this PhD project has been to develop systematic approaches that contribute to the reliability qualification of new subsea equipment and to the following-up of reliability in the Operational Phase.The main contributions from this PhD project are:• A technology qualification framework which is integrated with a product development model, and highlights the key features of commonly used TQP approaches.• A method for reliability prediction of new subsea equipment based on comparison with similar topside equipment and using the available field data.• An approach for how to consider and monitor human and organizational factors (HOFs) influencing common cause failures (CCFs) in the Operational Phase. Along with suggestion of supplementary questions to be added into the IEC 61508 approach for determining CCF factor.• An approach for failure rate updating during various product’s life cycle.• An approach for reliability prediction of offshore oil and gas equipment operating in arctic environment based on proportional hazard model and the levels of data availability.• An approach for outlining the reliability improvement process for subsea equipment that can be integrated with the product development process of Murthy et al. [57]. The results of this thesis may academically be used by researchers with interest in the same research field and practically be used by producers, suppliers, end users, decision-makers and other organizations within the field of subsea equipment and oil and gas industry. The generic principles from the proposed frameworks, or methods with minor modifications can also be applied for other new equipments in other industry sector where high reliability is a requirement, such as military, aviation, and so on. Therefore, it is important to share the contributions and ideas for further work with others. The contributions have been presented in eight articles, where two have been published in international journals, one have been submitted for publication, and five have been presented at conferences and have been published in conference proceedings. Currently, there are several TQP approaches have been suggested, but only two of these approaches are mainly used in the Norwegian offshore oil and gas industry; one proposed by Det Norske Veritas (DNV) in their recommended practice DNV-RP-A203 and one based on NASA’s technology readiness levels (TRLs) approach. Combinations of the two approaches are also used. This PhD thesis presents and discusses the main TQP approaches highlights challenges related to methodological and procedural issues and provides a set of suggestions for improvement. Criteria are established to facilitate comparison and identification of strengths and weaknesses of the TQP approaches. These results, combined with a thorough literature review, have been used to develop a framework that is practical for qualifying new subsea systems. As part of the TQP, reliability analyses and predictions are performed in the early stages of product development process. Currently, no practical method is available that can be used to extrapolate the available reliability data from similar and known systems and come up to a failure rate prediction for new systems operating in a different environment. This PhD thesis suggests a practical approach on how to predict the failure rate of new subsea systems that has been adapted (i.e., “marinized”) from known topside systems. The reliability assessment should not finish when the equipment enters the operating Phase, but should be followed-up during the Operational and maintenance Phases. Safety-instrumented systems (SISs) are important safety barriers in many technical systems in the subsea industry. CCFs represent a serious threat to the reliability of SISs. For quantitatively incorporating the effects of CCFs, the beta-factor model is often used. During the Operational Phase of SIS, the hardware architecture and the components will usually remain unchanged. Therefore, any changes in CCF might be as a result of factors including environmental exposure or human and organizational acts. This PhD thesis highlights the importance of HOFs in estimation of β for SISs during the Operational Phase.In addition this PhD thesis suggests a set of supplementary questions to the existing methods of beta estimation for SIS such as IEC 61508 approach, for more accurate determination of beta-factor. HOFs are difficult to predict, and susceptible to be changed during the Operational Phase. Without proper management, changing HOFs may cause the SIS reliability to drift out of its required value. This PhD thesis also proposes a framework to follow the HOFs effects and to manage them such that the reliability requirement can be maintained. Failure rate prediction provides a quantitative basis for decision-making regarding the adequacy of a design from the early Phases in the life cycle. In reallife operation and maintenance, the operating and environmental conditions may change compared to what was assumed by the producer in the design and development Phases. Changes in these conditions and unexpected disruptions may make the current predicted failure rate inaccurate and updating is required as a response to such disruptions and changes. This PhD thesis discusses the need for failure rate prediction in the various Phases of a product’s life cycle and proposes a framework for updating the failure rate prediction to obtain a more realistic prediction. As the offshore oil and gas industry is currently considers moving into the arctic region. The harsh arctic environment will have an unavoidable influence on the reliability of the equipment operated in it. To understand this influence is of vital importance to ensure the reliability of the equipment and the production availability of the systems. Several types of data, such as data on design, production, usage intensity, and operating environment are required to assess and verify the reliability of the equipment. This PhD thesis proposes a framework for reliability assessment based on proportional hazards modeling and various types of data. It presents important arctic factors influencing the physical performance and discusses how these may influence the reliability of the equipment. Developing a product with high reliability cannot be achieved overnight and the subsea industry has to adopt a long-term improvement strategy and needs to learn from other industries that are exposed to similar strict reliability requirements, such as the nuclear, aviation, and space industries. This PhD thesis outlines how to integrate continuous reliability improvement into the various Phases of the development of new subsea equipment, according to the product development model of Murthy et al. [57]. The areas for further research regarding this PhD project and proposed frameworks and method can be classified into three categories: (1) Development and improvement of proposed frameworks and method, (2) Practical implementation of them into existing industry practices, and (3) Handling of uncertainty.PhD i produksjons- og kvalitetsteknikkPhD in Production and Quality Engineerin
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Human and organisational factors in the Operational Phase of safety instrumented systems: A new approach
Safety Science, 2010Co-Authors: M A H Martin Schönbeck, Marvin Rausand, J.l. RouvroyeAbstract:The international standards IEC 61508 and IEC 61511, which provide a general framework for the design and implementation of safety instrumented systems, require quantification of the achieved risk reduction, expressed as a safety integrity level (SIL). Human and organisational factors affect the performance of safety instrumented systems during operation and may threaten the achieved SIL, but this is usually not explicitly accounted for. This article presents a new approach to address human and organisational factors in the Operational Phase of safety instrumented systems. This approach gives a prediction of the Operational SIL and can also be used to improve safety. It shows which human and organisational factors are most in need of improvement and it provides guidance for preventive or corrective action. Finally, the approach can be used as part of a SIL monitoring strategy in order to maintain the achieved SIL at the required level during the Operational Phase.
Christoph H. Keitel - One of the best experts on this subject based on the ideXlab platform.
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Sampling entropies and Operational Phase-space measurement. II. Detection of quantum coherences
Physical review. A Atomic molecular and optical physics, 1995Co-Authors: Vladimir Buzek, Christoph H. Keitel, Peter L. KnightAbstract:We use the Operational Phase-space distributions and sampling entropies developed in the preceding paper [V. Bu\ifmmode \check{z}\else \v{z}\fi{}ek, C. H. Keitel, and P. L. Knight, Phys. Rev. A 51, 2575 (1995)] to discuss the nature of quantum interference between components of superpositions of states. We show how the Wehrl entropy, a special case of the sampling entropy, is a useful discriminator between different kinds of superpositions and of statistical mixtures, and is determined essentially by the coherent-state content. Apart from interference terms, this content is given by the quantum uncertainty of a single coherent state and the classical contribution to the number of coherent states necessary to tile the dominant Phase-space ``patch'' representing the quantum state of interest. We illustrate these ideas using nonclassical superpositions of coherent states, where interference modifies the Phase-space distributions, and show how these features are sensitive to dissipation.
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Sampling entropies and Operational Phase-space measurement. I. General formalism
Physical review. A Atomic molecular and optical physics, 1995Co-Authors: Vladimir Buzek, Christoph H. Keitel, Peter L. KnightAbstract:We present an entropic description of quantum-mechanical states based on an Operational approach to a Phase-space measurement. We give a simple Phase-space interpretation of sampling entropies in terms of which we derive very general entropic uncertainty relations reflecting the degree of the Phase-space uncertainty of the quantum-mechanical state in the given measurement (i.e., for a given ``quantum-ruler'' state). We relate the sampling entropy to the von Neumann and Shannon entropy and show that the Wehrl entropy represents a particular example of a sampling entropy when the quantum ruler is represented by coherent states.
