973 resultados para Measurement theory
Resumo:
In this paper, a model of the measuring process of sonic anemometers with more than one measuring path is presented. The main hypothesis of the work is that the time variation of the turbulent speed field during the sequence of pulses that produces a measure of the wind speed vector affects the measurement. Therefore, the previously considered frozen flow, or instantaneous averaging, condition is relaxed. This time variation, quantified by the mean Mach number of the flow and the time delay between consecutive pulses firings, in combination with both the full geometry of sensors (acoustic path location and orientation) and the incidence angles of the mean with speed vector, give rise to significant errors in the measurement of turbulence which are not considered by models based on the hypothesis of instantaneous line averaging. The additional corrections (relative to the ones proposed by instantaneous line-averaging models) are strongly dependent on the wave number component parallel to the mean wind speed, the time delay between consecutive pulses, the Mach number of the flow, the geometry of the sensor and the incidence angles of mean wind speed vector. Kaimal´s limit k W1=1/l (where k W1 is the wave number component parallel to mean wind speed and l is the path length) for the maximum wave numbers from which the sonic process affects the measurement of turbulence is here generalized as k W1=C l /l, where C l is usually lesser than unity and depends on all the new parameters taken into account by the present model.
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In this paper a model for the measuring process of sonic anemometers (ultrasound pulse based) is presented. The differential equations that describe the travel of ultrasound pulses are solved in the general case of non-steady, non-uniform atmospheric flow field. The concepts of instantaneous line-average and travelling pulse-referenced average are established and employed to explain and calculate the differences between the measured turbulent speed (travelling pulse-referenced average) and the line-averaged one. The limit k1l=1 established by Kaimal in 1968, as the maximum value which permits the neglect of the influence of the sonic measuring process on the measurement of turbulent components is reviewed here. Three particular measurement cases are analysed: A non-steady, uniform flow speed field, a steady, non-uniform flow speed field and finally an atmospheric flow speed field. In the first case, for a harmonic time-dependent flow field, Mach number, M (flow speed to sound speed ratio) and time delay between pulses have revealed themselves to be important parameters in the behaviour of sonic anemometers, within the range of operation. The second case demonstrates how the spatial non-uniformity of the flow speed field leads to an influence of the finite transit time of the pulses (M≠0) even in the absence of non-steady behaviour of the wind speed. In the last case, a model of the influence of the sonic anemometer processes on the measurement of wind speed spectral characteristics is presented. The new solution is compared to the line-averaging models existing in the literature. Mach number and time delay significantly distort the measurement in the normal operational range. Classical line averaging solutions are recovered when Mach number and time delay between pulses go to zero in the new proposed model. The results obtained from the mathematical model have been applied to the calculation of errors in different configurations of practical interest, such as an anemometer located on a meteorological mast and the transfer function of a sensor in an atmospheric wind. The expressions obtained can be also applied to determine the quality requirements of the flow in a wind tunnel used for ultrasonic anemometer calibrations.
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In quantum measurement theory it is necessary to show how a, quantum source conditions a classical stochastic record of measured results. We discuss mesoscopic conductance using quantum stochastic calculus to elucidate the quantum nature of the measurement taking place in these systems. To illustrate the method we derive the current fluctuations in a two terminal mesoscopic circuit with two tunnel barriers containing a single quasi bound state on the well. The method enables us to focus on either the incoming/ outgoing Fermi fields in the leads, or on the irreversible dynamics of the well state itself. We show an equivalence between the approach of Buttiker and the Fermi quantum stochastic calculus for mesoscopic systems.
Resumo:
The research around performance measurement and management has focused mainly on the design, implementation and use of performance measurement systems. However, there is little evidence about the actual impacts of performance measurement on the different levels of business and operations of organisations, as well as the underlying factors that lead to a positive impact of performance measurement. The study thus focuses on this research gap, which can be considered both important and challenging to cover. The first objective of the study was to examine the impacts of performance measurement on different aspects of management, leadership and the quality of working life, after which the factors that facilitate and improve performance and performance measurement at the operative level of an organisation were examined. The second objective was to study how these factors operate in practice. The third objective focused on the construction of a framework for successful operative level performance measurement and the utilisation of the factors in the organisations. The research objectives have been studied through six research papers utilising empirical data from three separate studies, including two sets of interview data and one of quantitative data. The study applies mainly the hermeneutical research approach. As a contribution of the study, a framework for successful operative level performance measurement was formed by matching the findings of the current study and performance measurement theory. The study extents the prior research regarding the impacts of performance measurement and the factors that have a positive effect on operative level performance and performance measurement. The results indicate that under suitable circumstances, performance measurement has positive impacts on different aspects of management, leadership, and the quality of working life. The results reveal that for example the perception of the employees and the management of the impacts of performance measurement on leadership style differ considerably. Furthermore, the fragmented literature has been reorganised into six factors that facilitate and improve the performance of the operations and employees, and the use of performance measurement at the operative level of an organisation. Regarding the managerial implications of the study, managers who operate around performance measurement can utilise the framework for example by putting the different phases of the framework into practice.
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The goal of this research – which is to critically analyze current theories and methods of intangible assets evaluation and potentially develop and test new methodology based on the practical example(s) in the IT industry. Having this goal in mind the main research questions in this paper will be: What are advantages and disadvantages of the current practices of measurement intellectual capital or valuation of intangible assets? How to properly measure intellectual capital in IT? Resulting method exhibits a new unique approach to the IC measurement and potentially even larger field of application. Despite the fact that in this particular research, I focused my attention on IT (Software and Internet services cluster – to be exact), the logic behind the method is applicable within any industry since the method is designed to be fully compliant with measurement theory and thus can be properly scaled for any application. Building a new method is a difficult and iterative process: in the current iteration the method stands out as rather a theoretical concept rather than a business tool, however even current concept totally fulfills its purpose as a benchmarking tool for measuring intellectual capital in IT industry.
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Since Ranzini suggested supplementing the SPT test with measurement of the torque required to turn the split spoon sampler after driving, many Brazilian engineers have been using this in the design of pile foundations. This paper presents a study of the rod length influence in the torque measurement. A theoretical study of material resistance considering torsion and bending in a thin wall tubular steel shaft was performed. It makes possible to conclude that the shearing tension caused by the proper weight represents less than 1% of the shearing tension caused by the turning moment. In addition, an experimental study was done with electric torquemeters fixed in a horizontal rod system. The tests were being carried out to analyze rods of one meter to twenty meters in length and the measurements were collected at the ends of each rod length verifying the efficiency data. As a result, it is possible to verify that the torque difference through rod length is lower than minimum scales of mechanical torquemeters that are used on practical engineering. Also a fact to be considered is a big torque loss for values under 20 N.m of applied torque. This way, the SPT-T is not adequate to low consistency soil. Copyright ASCE 2007.
Resumo:
According to Bandura (1997) efficacy beliefs are a primary determinant of motivation. Still, very little is known about the processes through which people integrate situational factors to form efficacy beliefs (Myers & Feltz, 2007). The aim of this study was to gain insight into the cognitive construction of subjective group-efficacy beliefs. Only with a sound understanding of those processes is there a sufficient base to derive psychological interventions aimed at group-efficacy beliefs. According to cognitive theories (e.g., Miller, Galanter, & Pribram, 1973) individual group-efficacy beliefs can be seen as the result of a comparison between the demands of a group task and the resources of the performing group. At the center of this comparison are internally represented structures of the group task and plans to perform it. The empirical plausibility of this notion was tested using functional measurement theory (Anderson, 1981). Twenty-three students (M = 23.30 years; SD = 3.39; 35 % females) of the University of Bern repeatedly judged the efficacy of groups in different group tasks. The groups consisted of the subjects and another one to two fictive group members. The latter were manipulated by their value (low, medium, high) in task-relevant abilities. Data obtained from multiple full factorial designs were structured with individuals as second level units and analyzed using mixed linear models. The task-relevant abilities of group members, specified as fixed factors, all had highly significant effects on subjects’ group-efficacy judgments. The effect sizes of the ability factors showed to be dependent on the respective abilities’ importance in a given task. In additive tasks (Steiner, 1972) group resources were integrated in a linear fashion whereas significant interaction between factors was obtained in interdependent tasks. The results also showed that people take into account other group members’ efficacy beliefs when forming their own group-efficacy beliefs. The results support the notion that personal group-efficacy beliefs are obtained by comparing the demands of a task with the performing groups’ resources. Psychological factors such as other team members’ efficacy beliefs are thereby being considered task relevant resources and affect subjective group-efficacy beliefs. This latter finding underlines the adequacy of multidimensional measures. While the validity of collective efficacy measures is usually estimated by how well they predict performances, the results of this study allow for a somewhat internal validity criterion. It is concluded that Information Integration Theory holds potential to further help understand people’s cognitive functioning in sport relevant situations.
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One of the most significant paradigm shifts of modern business management is that individual businesses no longer compete as solely autonomous entities, but rather as supply chains. Firms worldwide have embraced the concept of supply chain management as important and sometimes critical to their business. The idea of a collaborative supply chain is to gain a competitive advantage by improving overall performance through measuring a holistic perspective of the supply chain. However, contemporary performance measurement theory is somewhat fragmented and fails to support this idea. Therefore, this research develops and applies an integrated supply chain performance measurement framework that provides a more holistic approach to the study of supply chain performance measurement by combining both supply chain macro processes and decision making levels. Therefore, the proposed framework can provide a balanced horizontal (cross-process) and vertical (hierarchical decision) view and measure the performance of the entire supply chain system. Firstly, literature on performance measurement frameworks and performance measurement factors of supply chain management will help to develop a conceptual framework. Next the proposed framework will be presented. The framework will be validated through in-depth interviews with three Thai manufacturing companies. The fieldwork combined varied sources in order to understand the views of manufacturers on supply chain performance in the three case study companies. The collected data were analyzed, interpreted, and reported using thematic analysis and analysis hierarchy process (AHP), which was influenced by the study’s conceptual framework. This research contributes a new theory of supply chain performance measurement and knowledge on supply chain characteristics of a developing country, Thailand. The research also affects organisations by preparing decision makers to make strategic, tactical and operational level decisions with respect to supply chain macro processes. The results from the case studies also indicate the similarities and differences in their supply chain performance. Furthermore, the implications of the study are offered for both academic and practical use.
Resumo:
Purpose – This paper aims to respond to John Rossiter's call for a “Marketing measurement revolution” in the current issue of EJM, as well as providing broader comment on Rossiter's C-OAR-SE framework, and measurement practice in marketing in general. Design/methodology/approach – The paper is purely theoretical, based on interpretation of measurement theory. Findings – The authors find that much of Rossiter's diagnosis of the problems facing measurement practice in marketing and social science is highly relevant. However, the authors find themselves opposed to the revolution advocated by Rossiter. Research limitations/implications – The paper presents a comment based on interpretation of measurement theory and observation of practices in marketing and social science. As such, the interpretation is itself open to disagreement. Practical implications – There are implications for those outside academia who wish to use measures derived from academic work as well as to derive their own measures of key marketing and other social variables. Originality/value – This paper is one of the few to explicitly respond to the C-OAR-SE framework proposed by Rossiter, and presents a number of points critical to good measurement theory and practice, which appear to remain underdeveloped in marketing and social science.
Resumo:
The optimal discrimination of nonorthogonal quantum states with minimum error probability is a fundamental task in quantum measurement theory as well as an important primitive in optical communication. In this work, we propose and experimentally realize a new and simple quantum measurement strategy capable of discriminating two coherent states with smaller error probabilities than can be obtained using the standard measurement devices: the Kennedy receiver and the homodyne receiver.
Resumo:
We present a potential realization of the Greenberger-Horne-Zeilinger all or nothing contradiction of quantum mechanics with local realism using phase measurement techniques in a simple photon number triplet. Such a triplet could be generated using nondegenerate parametric oscillation. [S0031-9007(98)07671-6].
Resumo:
In this paper we examine the problem of compositional data from a different startingpoint. Chemical compositional data, as used in provenance studies on archaeologicalmaterials, will be approached from the measurement theory. The results will show, in avery intuitive way that chemical data can only be treated by using the approachdeveloped for compositional data. It will be shown that compositional data analysis is aparticular case in projective geometry, when the projective coordinates are in thepositive orthant, and they have the properties of logarithmic interval metrics. Moreover,it will be shown that this approach can be extended to a very large number ofapplications, including shape analysis. This will be exemplified with a case study inarchitecture of Early Christian churches dated back to the 5th-7th centuries AD
Resumo:
Aim of this contribution is to illustrate the state of the art of smart antenna research from several perspectives. The bow is drawn from transmitter issues via channel measurements and modeling, receiver signal processing, network aspects, technological challenges towards first smart antenna applications and current status of standardization. Moreover, some future prospects of different disciplines in smart antenna research are given.
Resumo:
Kiristyvät markkinat ajavat yritykset tehostamaan toimintaansa. Suorituskyvyn mittaaminen on jo olennainen osa suomalaista yrityskulttuuria. Mittaamisen päätehtävä on tuottaa yritysjohdolle relevanttia informaatiota yrityksen tilasta ja auttaa valvomaan ja kehittämään toimintaa. Tämän tutkimuksen kohteena on palvelukonsernin Iiiketoimintayksikön suorituskyvyn mittaaminen. Tutkimuksen päätavoitteina on 1. valita palvelukonsernin liiketoimintayksikölle sopiva suorituskyvyn mittausjärjestelmä, 2. valita käytännöllinen implementointimalli sekä 3. laatia suorituskykymittaristo palvelukonsernin liiketoimintayksikölle. Tämä tutkimus jakautuu kahteen vaiheeseen. Ensimmäisessä vaiheessa tutkimuksen kohteena on suorituskyvyn teoria ja neljä erilaista mittausmenetelmää, joista valitaan yksi Iiiketoimintayksikön suorituskyvyn mittausjärjestelmäksi sekä syvempää tarkastelua varten. Tutkimuksen toisessa vaiheessa tutkitaan valitun mittausjärjestelmän ominaisuuksia strategisena johtamisjärjestelmänä sekä sen implementointimalleja. Toisen vaiheen keskeisin tutkimusosuus on suorituskykymittausjärjestelmän laadinta. Työn lopputuloksena syntyy palvelukonsernin Iiiketoimintayksikön suorituskyvyn mittausjärjestelmä sekä jatkotoimenpide-ehdotus Balanced Scorecardin laajentamiseksi Iiiketoimialan ohjausjärjestelmäksi.
Resumo:
Le logiciel de simulation des données et d'analyse est Conquest V.3