704 research outputs found

    Semiclassical approach to the work distribution

    Get PDF
    Work in closed quantum systems is usually defined by a two-point measurement. This definition of work is compatible with quantum fluctuation theorems but it fundamentally differs from its classical counterpart. In this paper, we study the correspondence principle in quantum chaotic systems. We derive a semiclassical expression of the work distribution for chaotic systems undergoing a general, finite time, process. This semiclassical distribution converges to the classical distribution in the usual classical limit. We show numerically that, for a particle inside a chaotic cavity, the semiclassical distribution provides a good approximation to quantum distribution.Fil: Garcia-Mata, Ignacio. Consejo Nacional de Investigaciones CientĂ­ficas y TĂŠcnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones FĂ­sicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Instituto de Investigaciones FĂ­sicas de Mar del Plata; ArgentinaFil: Roncaglia, Augusto Jose. Consejo Nacional de Investigaciones CientĂ­ficas y TĂŠcnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de FĂ­sica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FĂ­sica de Buenos Aires; ArgentinaFil: Wisniacki, Diego Ariel. Consejo Nacional de Investigaciones CientĂ­ficas y TĂŠcnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de FĂ­sica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FĂ­sica de Buenos Aires; Argentin

    PORTUGUESE AVERAGE COST OF CAPITAL

    Get PDF
    The oldest Portuguese share index still being calculated is the BVL/PSI-General, one which started the daily series on 5/Jan/1988 with a base value of 1000 points. Everyday a single value is computed based on the closing prices of all the shares included in the sample. Also, all corporate events affecting the price of any share beyond market sentiment are taken into account through proper adjustments, either in the numerator or the denominator of the formula. However, for dates before January 1988, there is nothing comparable to this index since the two different series known either never disclosed the methodology adopted to calculate the index or followed solutions not compatible with the above index. The present paper explains the solutions adopted to replicate as closely as possible the methodology of the BVL-General index to the main market of the Lisbon Exchange for the period 1978 – 1987. This is the first estimate of the historical Equity Risk Premium in Portugal above short-term riskfree rate from the re-opening of the market following the Carnation Revolution (and the accompanying nationalizations), to the present. In showing a value of the same order of magnitude found in other countries, the paper invites further studies on the effects of political decisions such as privatizations and joining the European Union. JEL codes:

    Changing Role of Mexican Accounting Firms and of Comisario, and Response to Sarbanes-Oxley

    Get PDF

    Smart Sensors' Role in Integrated System Health Management

    Get PDF
    During the last decade, there has been a major effort in the aerospace industry to reduce the cost per pond of payload and become competitive in the international market. Competition from Europe, Japan, and China has reduced this cost to almost a third from 1990 to 2000. This cost has leveled in recent years to an average price of around $12,000/pound of payload. One of NASA's goals is to promote the development of technologies to reduce this cost by a factor of 10 or more Exploration of space, specially manned exploration missions, involves very complex launch and flight vehicles, associated ground support systems, and extensive human support during all phases of the mission. When considering the Space Shuttle Program, we can see that vehicle and ground support systems' processing, operation, and maintenance represent a large percentage of the program cost and time. Reducing operating, processing and maintenance costs will greatly reduce the cost of Exploration programs. The Integrated System Health Management (ISHM) concept is one of the technologies that will help reduce these operating, processing and maintenance costs. ISHM is an integrated health monitoring system applicable to both flight and ground systems. It automatically and autonomously acquires information from sensors and actuators and processes that information using the ISHM-embedded knowledge. As a result, it establishes the health of the system based on the acquired information and its prior knowledge. When this concept is fully implemented, ISHM systems shall be able to perform failure prediction and remediation before actual hard failures occurs, preventing its costly consequences. Data sources, sensors, and their associated data acquisition systems, constitute the foundation of the system. A smart sensing architecture is required to support the acquisition of reliable, high quality data, required by the ISHM. A thorough definition of the smart sensor architectures, their embedded diagnostic agents, and communication protocols need to be established and standardized to allow the embedding and exchange of health information among sensors and ISHM. This workshop is aimed to foster the exchange of ideas and lessons learned between government, industry and academia to aid in the establishment of ISHM (and smart sensors) standards and guidelines as well as to identify present technology gaps that will have to be overcome to successfully achieve this goal

    A Platinum molecular complex immobilised on the surface of graphene as active catalyst in alkyne hydrosilylation

    Get PDF
    Abstract A platinum complex bearing a N‐heterocyclic carbene (NHC) ligand functionalised with a pyrene‐tag is immobilised onto the surface of reduced graphene oxide (rGO). The hybrid material composed of an organometallic complex and a graphene derivative is ready available in a single‐step process under mild reaction conditions. This methodology preserves the inherent properties of the active catalytic centre and the support. The platinum hybrid material is an efficient catalyst in hydrosilylation of alkynes and can be recycled and reused for ten runs without significant loss of activity due to its high stability. Interestingly, the catalytic properties of the platinum complex are enhanced after immobilisation onto graphene. The influence of graphene in hydrosilylation of alkynes is discussed

    Intelligent Devices - Sensors and Actuators - A KSC Perspective

    Get PDF
    The primary objective of this workshop is to identify areas of advancement in sensor measurements and technologies that will help to define standard practices and procedures that will better enable the infusion into flight programs of sensors with improved capabilities but limited or no flight heritage. These standards would be crucial to demonstrating a methodology for validating current models while also creating the possibility of being able to have sufficient data to either update these models (e. g., spatial or temporal resolution, etc.) or develop new models based on the ability to simulate the new measured physical parameters. The workshop is also intended to narrow the gap between sensor measurements (and techniques), data processing techniques and the ability to make use of that data by gathering together experts in the field for a short workshop. This collaboration will unite NASA and other government agencies with contractor capabilities industry-wide to prevent duplication, spawn synergistic growth in sensor technology, help analysts make good engineering decisions and help focus new sensor maturation efforts to better meet future flight program customers' needs. This is the first such workshop designed to specifically address establishing a standardized protocol/methodology for demonstrating the technology readiness of non-flight heritage sensor systems. While other similar workshops are held covering many areas of interest to the sensor development community, no other meeting is specific enough to address this vital but often overlooked topic. By encouraging cross-fertilization of ideas from instrument experts from many different backgrounds, it is hoped that this workshop will initiate innovative new ideas and concepts in sensor development, calibration and validation. It is anticipated this workshop will repeat periodically as needed

    Recent developments in the applications of palladium complexes bearing N-heterocyclic carbene ligands

    Get PDF
    N-heterocyclic carbene (NHC) ligands have become ubiquitous ligands in the preparation of metal complexes with new catalytic applications. Mainly due to their applications in C-C bond formation reactions, a plethora of novel palladium-NHC complexes has been described, and a large number of review articles describing their chemistry have been published. In an attempt to provide a new vision of the topic, this article will focus our attention on the development of new palladium complexes with NHC ligands, paying special attention to their applications in catalytic processes other than the classical C-C coupling reactions. This article is divided in the following sections: i) design of reusable Pd-NHC complexes, ii) latest advances in the use of Pd- NHC complexes in homogenous catalysis and, iii) other applications of Pd-NHC complexes

    Curve Adjustment Method: Deriving a Formula from a Graph

    Get PDF
    Audio Engineering, and others technical fields, need more mathematical-based methodologies. There are procedures in studio or live recordings that have not been tabulated yet and depend entirely on human experience and appreciation. Audio engineers whether at studios or live-music settings need tools that allow them to translate their daily personal annotations, rules of thumb, live-music and/or empirical experiments into mathematical expressions or formulas that can benefit the practitioners to get rid of the dependency on the personal and individual appreciation. In this paper, the authors attempt to describe a general procedure to convert any group of into a graph

    Multimetallic (de)hydrogenation catalysed processes

    Get PDF
    The use of different metals working together in a synergistic way, allows synthetic transformations that are not achievable by other means. The metal cooperation becomes important in catalytic processes for the synthesis of sophisticated molecules or difficult transformations. A rationale design of multimetallic catalysed processes entails metal complexes and reaction conditions being compatible, which in general is not straightforward. A key feature for success found in all systems dealing with multimetallic processes is catalyst stability. The use of robust metal complexes increases the probability of success in the search of tandem catalytic processes. This microreview is based on the recent and most important findings of multimetallic catalysed processes that involved (de)hydrogenation reactions. The field constitutes a research area that is full of potential and can be foreseen that relevant applications will be described in the near future.MINECO (CTQ2015-69153-C2-2-R), Generalitat Valenciana (AICO/2015/039), Universitat Jaume I (P1.1B2015-09
    • …
    corecore