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21 – 30 of over 33000Julia Darby and Simon Wren‐Lewis
An understanding of the determination of real wages is crucial inanalysing the determination of the natural rate of unemployment orNAIRU. Uses cointegration techniques to examine…
Abstract
An understanding of the determination of real wages is crucial in analysing the determination of the natural rate of unemployment or NAIRU. Uses cointegration techniques to examine a core theoretical model of the long‐run determinants of real wages involving unit labour costs, unemployment, union power and the replacement ratio. Considers the different measures of union power and the duration of unemployment and alternative specifications involving the “wedge” but a robust cointegrating relationship is not found. These results can be interpreted in several ways: concepts such as union power or the “generosity” of benefits may be measured inadequately; the theoretical understanding of the long‐run determinants of real earnings may remain seriously incomplete; alternatively the short spans of data examined may be insufficient for the application of cointegration techniques, although the sample sizes examined here are fairly typical of most macroeconomic time series.
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Michael Nierla, Michael Loeffler, Manfred Kaltenbacher and Stefan Johann Rupitsch
The numerical computation of magnetization processes in moving and rotating assemblies requires the usage of vector hysteresis models. A commonly used model is the so-called…
Abstract
Purpose
The numerical computation of magnetization processes in moving and rotating assemblies requires the usage of vector hysteresis models. A commonly used model is the so-called Mayergoyz vector Preisach model, which applies the scalar Preisach model into multiple angles of the halfspace. The usage of several scalar models, which are optionally weighted differently, enables the description of isotropic as well as anisotropic materials. The flexibility is achieved, however, at the cost of multiple scalar model evaluations. For solely isotropic materials, two vector Preisach models, based on an extra rotational operator, might offer a lightweight alternative in terms of evaluation cost. The study aims at comparing the three mentioned models with respect to computational efficiency and practical applicability.
Design/methodology/approach
The three mentioned vector Preisach models are compared with respect to their computational costs and their representation of magnetic polarization curves measured by a vector vibrating sample magnetometer.
Findings
The results prove the applicability of all three models to practical scenarios and show the higher efficiency of the vector models based on rotational operators in terms of computational time.
Originality/value
Although the two vector Preisach models, based on an extra rotational operator, have been proposed in 2012 and 2015, their practical application and inversion has not been tested yet. This paper not only shows the usability of these particular vector Preisach models but also proves the efficiency of a special stageless evaluation approach that was proposed in a former contribution.
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A Description of the Development of the Bristol Siddeley Pegasus and Plenum Chamber Burning for the BS.100 and an Outline of the Performance of a V/S.T.O.L Subsonic Strike Fighter…
Abstract
A Description of the Development of the Bristol Siddeley Pegasus and Plenum Chamber Burning for the BS.100 and an Outline of the Performance of a V/S.T.O.L Subsonic Strike Fighter Utilizing a Vectored Thrust Engine with PCB as Compared with a Composite Power Plant Fighter and a Vectored Thrust Type without PCB. The Bristol Siddeley Pegasus vectored‐thrust turbo‐Tan has now been in operation for six years, and during that time has been developed to a fully operational stan‐dard in the Hawker Siddeley Kestrel V/S.T.O.L. sub‐sonic strike fighter. Initial development of a second‐generation V/ S.T.O.L. strike fighter for supersonic flight necessitated thrust augmentation by combustion in the normally cold by‐pass flow. This gave rise to the design and development of a suitable combustion system, now known as ‘Plenum Chamber Burning’, or ‘PCB’. This paper summarizes the satisfactory development of the Pegasus vectored‐thrust turbofan, gives some description of the PCB system development, and shows how the application of this system to a V/S.T.O.L. subsonic strike fighter vectored‐thrust power plant gives the latter considerable superiority when compared with an equivalent composite power plant configuration.
József Valyon and Gábor Horváth
The purpose of this paper is to present extended least squares support vector machines (LS‐SVM) where data selection methods are used to get sparse LS‐SVM solution, and to…
Abstract
Purpose
The purpose of this paper is to present extended least squares support vector machines (LS‐SVM) where data selection methods are used to get sparse LS‐SVM solution, and to overview and compare the most important data selection approaches.
Design/methodology/approach
The selection methods are compared based on their theoretical background and using extensive simulations.
Findings
The paper shows that partial reduction is an efficient way of getting a reduced complexity sparse LS‐SVM solution, while partial reduction exploits full knowledge contained in the whole training data set. It also shows that the reduction technique based on reduced row echelon form (RREF) of the kernel matrix is superior when compared to other data selection approaches.
Research limitations/implications
Data selection for getting a sparse LS‐SVM solution can be done in the different representations of the training data: in the input space, in the intermediate feature space, and in the kernel space. Selection in the kernel space can be obtained by finding an approximate basis of the kernel matrix.
Practical implications
The RREF‐based method is a data selection approach with a favorable property: there is a trade‐off tolerance parameter that can be used for balancing complexity and accuracy.
Originality/value
The paper gives contributions to the construction of high‐performance and moderate complexity LS‐SVMs.
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Mark J. Nigrini and William Karstens
This paper develops a vector variation score that quantifies the change in an array of data points from period-to-period. The array could be the amounts reported on an income tax…
Abstract
Purpose
This paper develops a vector variation score that quantifies the change in an array of data points from period-to-period. The array could be the amounts reported on an income tax return, the closing stock prices for a set of listed companies, the monthly sales amounts for retail locations or the monthly balances in general ledger accounts.
Design/methodology/approach
The score is grounded in analytic geometry. The angle θ measures whether the changes were uniformly spread across the line items. The item(s) with the largest contribution(s) to the score can be identified. Line items can be weighted such that they contribute less than fully to the score.
Findings
The method can identify tax returns with large year-on-year changes. The method can identify the fact that the price movements during earnings season are less dependent than is usually the case. The method can identify anomalies in reported sales amounts. The method should be able to identify ledger accounts’ large abnormal changes.
Research limitations/implications
Auditors will need to be trained to interpret the results and to reduce the number of false positives.
Practical implications
The score could be used in both external and internal audit applications where auditors want to quantify and rank period-on-period changes in a search for outliers.
Originality/value
The change score is normalized to the [0, 1] range. The results can be plotted as a polar plot for display on an auditing dashboard. The contribution of a single line item can be calculated and line items can be weighted to prevent them from having an undue influence on the results.
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Fardin Hasanzad, Hasan Rastegar and Mohammad Pichan
This paper aims to investigate the common-mode voltage (CMV) issue of a three-phase four-leg voltage-source inverter. A new space vector modulation method, named as…
Abstract
Purpose
This paper aims to investigate the common-mode voltage (CMV) issue of a three-phase four-leg voltage-source inverter. A new space vector modulation method, named as three-dimensional active zero state Pulse-width modulation (PWM) (3-D AZSPWM), is proposed to reduce the CMV level.
Design/methodology/approach
PWM is a general method to generate the switching signals of the power converters in order to obtain high-quality output voltages. However, the CMV produced by PWM methods has become a serious problem. 3-D AZSPWM is proposed to solve this issue. In 3-D AZSPWM, instead of using zero voltage vectors with high CMV level, appropriate complementary non-zero vectors are introduced to synthesize reference vector. The proposed method is classified into four types of AZSPWM1(a), AZSPWM1(b), AZSPWM2(a) and AZSPWM2(b) based on different complementary vectors chosen for each type. An extend software simulation using MATLAB/Simulink is performed to verify the superior performance of the proposed methods.
Findings
Compared to other reduced CMV methods, the proposed method not only reduces the CMV but also retains the positive characteristics of the three-dimensional classical space vector PWM (3-D CSVPWM).
Originality/value
The proposed method does not suffer from linear modulation region limitation and also does not impose additional switching loss. Furthermore, calculated output voltage harmonic distortion factor illuminates acceptable quality of output voltage produced by the proposed method.
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Dongping Zhao, Gangfeng Wang, Jizhuang Hui, Wei Hou and Richard David Evans
The assembly quality of complex products is pivotal to their lifecycle performance. Assembly precision analysis (APA) is an effective method used to check the feasibility and…
Abstract
Purpose
The assembly quality of complex products is pivotal to their lifecycle performance. Assembly precision analysis (APA) is an effective method used to check the feasibility and quality of assembly. However, there is still a need for a systematic approach to be developed for APA of kinematic mechanisms. To achieve more accurate analysis of kinematic assembly, this paper aims to propose a precision analysis method based on equivalence of the deviation source.
Design/methodology/approach
A unified deviation vector representation model is adopted by considering dimension deviation, geometric deviation, joint clearance and assembly deformation. Then, vector loops and vector equations are constructed, according to joint type and deviation propagation path. A combined method, using deviation accumulation and sensitivity modeling, is applied to solve the kinematic APA of complex products.
Findings
When using the presented method, geometric form deviation, joint clearance and assembly deformation are considered selectively during tolerance modeling. In particular, the proposed virtual link model and its orientation angle are developed to determine joint deviation. Finally, vector loops and vector equations are modeled to express deviation accumulation.
Originality/value
The proposed method provides a new means for the APA of complex products, considering joint clearance and assembly deformation while improving the accuracy of APA, as much as possible.
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Business firms are subject to accelerating technological change and related changes in the strategic value framework. Mistakes due to the misperception and misunderstanding of…
Abstract
Purpose
Business firms are subject to accelerating technological change and related changes in the strategic value framework. Mistakes due to the misperception and misunderstanding of technology impacts have been very costly. The purpose of this paper is to investigate, describe and model the process of technological evolution as a dynamic value framework for strategy and related decision making.
Design/methodology/approach
The research centered on the evolution of technology‐value vectors and their economic and strategic impacts. Information was collected from various known academic and professional publications. The paper also benefited from feedback gained from the presentation of an earlier version at ISMOT, 2007, Hangchow, China.
Findings
The paper indicates firms often have difficulty transitioning from one phase of a technology‐value vector to another, especially when presented with a super radical innovation, possibly because of strategy and related decision making. The adaptability of firms, from phase to phase, may be improved by a clearer perception and understanding of the relevant technology‐value vectors or vector.
Research limitations/implications
As the technology‐value vector model is new and offers many new perspectives it will be subject to further research, refinement and validation. It is best used to assess and explore medium to high technology. It does not explore specific market aspects such as preferences, place and time which are left to future research.
Practical implications
The model develops a tool and concepts for a clearer view and understanding of the economic/market forces impacting medium to high‐technological evolution. It is expected that this will lead to improved related strategy and decision making in medium to high technology firms.
Originality/value
The paper develops and describes a model of the evolution of the technology‐value vector, which may act as a dynamic framework for strategy in medium to high‐technology industries. The research may have many other uses, including the management and planning of technology.
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Boštjan Brank and Adnan Ibrahimbegovic´
In this work we present interrelations between different finite rotation parametrizations for geometrically exact classical shell models (i.e. models without drilling rotation)…
Abstract
In this work we present interrelations between different finite rotation parametrizations for geometrically exact classical shell models (i.e. models without drilling rotation). In these kind of models the finite rotations are unrestricted in size but constrained in the 3‐d space. In the finite element approximation we use interpolation that restricts the treatment of rotations to the finite element nodes. Mutual relationships between different parametrizations are very clearly established and presented by informative commutative diagrams. The pluses and minuses of different parametrizations are discussed and the finite rotation terms arising in the linearization are given in their explicit forms.
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Gh. R. Heravi and R. Attarnejad
The purpose of this paper is to improve the effectiveness of ordinary reduction methods performance, in nonlinear dynamic analysis. In this paper, the error vector due to linear…
Abstract
The purpose of this paper is to improve the effectiveness of ordinary reduction methods performance, in nonlinear dynamic analysis. In this paper, the error vector due to linear and nonlinear dynamic analysis in generalized subspaces is extracted, and is decomposed into two independent components, namely outside and inside components. Based on the inside error component, a new iterative reduction method, one‐dimensional generalized subspace procedure (ODGS), is proposed where an innovative criterion is defined for updating the base vectors necessary for stiffness changes in nonlinear dynamic analysis. In this study, the performance of ODGS for linear and nonlinear analysis of elastodynamic systems including non‐proportional damping based on the Ritz generalized subspace has been proposed. Numerical examples show the competency of the proposed method in both economy and exactness. Time saving gained from the ODGS method could be recompensed to get much more accurate results consuming the same CPU time. This iterative method is more effective than the ordinary reduction methods. Since the method is directly derived from the discrete model based on the finite element method (FEM), the complexity of the structure does not affect directly the effectiveness of ODGS. Therefore, whenever the FEM is effectively capable to represent the topology of the structure, the ODGS results will also represent the system response properly. Same as any other reduction methods, accuracy of this iterative reduction method is directly related to the number of selected Ritz vectors, according to convergence criterion.
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