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Book part
Publication date: 18 July 2016

Matthew Lindsey and Robert Pavur

Research in the area of forecasting and stock inventory control for intermittent demand is designed to provide robust models for the underlying demand which appears at…

Abstract

Research in the area of forecasting and stock inventory control for intermittent demand is designed to provide robust models for the underlying demand which appears at random, with some time periods having no demand at all. Croston’s method is a popular technique for these models and it uses two single exponential smoothing (SES) models which involve smoothing constants. A key issue is the choice of the values due to the sensitivity of the forecasts to changes in demand. Suggested selections of the smoothing constants include values between 0.1 and 0.3. Since an ARIMA model has been illustrated to be equivalent to SES, an optimal smoothing constant can be selected from the ARIMA model for SES. This chapter will conduct simulations to investigate whether using an optimal smoothing constant versus the suggested smoothing constant is important. Since SES is designed to be an adapted method, data are simulated which vary between slow and fast demand.

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Advances in Business and Management Forecasting
Type: Book
ISBN: 978-1-78635-534-8

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Article
Publication date: 1 May 2000

D.S. Liyanapathirana, A.J. Deeks and M.F. Randolph

In finite element analysis of pile driving, the nodes of the finite element mesh are the most important locations for output stresses. Especially at the pile‐soil…

Abstract

In finite element analysis of pile driving, the nodes of the finite element mesh are the most important locations for output stresses. Especially at the pile‐soil interface, it is essential to obtain accurate nodal stresses. Several global and local stress smoothing methods available in the literature were reviewed and examined. Global methods are found to be computationally expensive, so results obtained from several local stress smoothing methods are compared. It is shown that accurate nodal stresses can be obtained by approximating the stress distribution inside four‐element patches by a polynomial with order equal to the order of the shape functions. Equally good results can be obtained by approximating the stress distribution inside each element by a bilinear surface. When a method taking into account both equilibrium and boundary conditions was applied, a set of ill‐conditioned matrices was produced for the four‐element patches. Such methods are therefore not recommended.

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Engineering Computations, vol. 17 no. 3
Type: Research Article
ISSN: 0264-4401

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Book part
Publication date: 16 December 2009

Zongwu Cai, Jingping Gu and Qi Li

There is a growing literature in nonparametric econometrics in the recent two decades. Given the space limitation, it is impossible to survey all the important recent…

Abstract

There is a growing literature in nonparametric econometrics in the recent two decades. Given the space limitation, it is impossible to survey all the important recent developments in nonparametric econometrics. Therefore, we choose to limit our focus on the following areas. In Section 2, we review the recent developments of nonparametric estimation and testing of regression functions with mixed discrete and continuous covariates. We discuss nonparametric estimation and testing of econometric models for nonstationary data in Section 3. Section 4 is devoted to surveying the literature of nonparametric instrumental variable (IV) models. We review nonparametric estimation of quantile regression models in Section 5. In Sections 2–5, we also point out some open research problems, which might be useful for graduate students to review the important research papers in this field and to search for their own research interests, particularly dissertation topics for doctoral students. Finally, in Section 6 we highlight some important research areas that are not covered in this paper due to space limitation. We plan to write a separate survey paper to discuss some of the omitted topics.

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Nonparametric Econometric Methods
Type: Book
ISBN: 978-1-84950-624-3

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Article
Publication date: 21 September 2015

Hongyu Zhao, Zhelong Wang, Qin Gao, Mohammad Mehedi Hassan and Abdulhameed Alelaiwi

The purpose of this paper is to develop an online smoothing zero-velocity-update (ZUPT) method that helps achieve smooth estimation of human foot motion for the ZUPT-aided…

Abstract

Purpose

The purpose of this paper is to develop an online smoothing zero-velocity-update (ZUPT) method that helps achieve smooth estimation of human foot motion for the ZUPT-aided inertial pedestrian navigation system.

Design/methodology/approach

The smoothing ZUPT is based on a Rauch–Tung–Striebel (RTS) smoother, using a six-state Kalman filter (KF) as the forward filter. The KF acts as an indirect filter, which allows the sensor measurement error and position error to be excluded from the error state vector, so as to reduce the modeling error and computational cost. A threshold-based strategy is exploited to verify the detected ZUPT periods, with the threshold parameter determined by a clustering algorithm. A quantitative index is proposed to give a smoothness estimate of the position data.

Findings

Experimental results show that the proposed method can improve the smoothness, robustness, efficiency and accuracy of pedestrian navigation.

Research limitations/implications

Because of the chosen smoothing algorithm, a delay no longer than one gait cycle is introduced. Therefore, the proposed method is suitable for applications with soft real-time constraints.

Practical implications

The paper includes implications for the smooth estimation of most types of pedal locomotion that are achieved by legged motion, by using a sole foot-mounted commercial-grade inertial sensor.

Originality/value

This paper helps realize smooth transitions between swing and stance phases, helps enable continuous correction of navigation errors during the whole gait cycle, helps achieve robust detection of gait phases and, more importantly, requires lower computational cost.

Details

Sensor Review, vol. 35 no. 4
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 24 June 2020

Awad Elsayed Awad Ibrahim, Tarek Abdelfattah and Khaled Hussainey

The authors examine whether managers switch from artificial income smoothing using discretionary accruals to real income smoothing around corporate governance reform in Egypt.

Abstract

Purpose

The authors examine whether managers switch from artificial income smoothing using discretionary accruals to real income smoothing around corporate governance reform in Egypt.

Design/methodology/approach

The sample comprises 61 non-financial companies listed on the Egyptian Stock Exchange for the years 2004–2011. The authors use discretionary accruals as a proxy for artificial income smoothing and income/loss from asset sales as a proxy for real income smoothing.

Findings

The authors offer a significant contribution to accounting literature by providing new empirical evidence on the trade-off between real smoothing technique (e.g. income/loss from asset sales) and discretionary accruals around governance reform in a developing country.

Research limitations/implications

This study suffers from some limitations. First, the study sample is limited to only 338 observations. However, this is due to collecting the data manually and to the small number of listed firms during the study period. Second, the study period ended in 2011 due to the unprecedented political instability after the 2011 Egyptian people revolution. Third, although this study examines the effect of corporate governance, not all the governance aspects have been examined in the study models due to the lack of data.

Practical implications

First, the results of the total samples reveal that managers prefer real income smoothing than accruals income smoothing. This result may confirm the literature arguments on the advantages of REM methods over AEM methods. Cohen et al. (2008) find that firms switch to manage earnings using REM methods and explain that REM methods are harder to detect because they depend on operating decisions (Schipper, 1989). REM can be undertaken anytime during the year (Gunny, 2010). Besides, REM could not be deemed a violation of accounting standards or regulations (MyVay, 2006).

Originality/value

The authors offer a significant contribution to accounting literature by providing new empirical evidence on the trade-off between real smoothing technique (e.g. income/loss from asset sales) and discretionary accruals around governance reform in a developing country.

Details

Journal of Applied Accounting Research, vol. 21 no. 4
Type: Research Article
ISSN: 0967-5426

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Article
Publication date: 25 February 2014

George A. Gravvanis and Christos K. Filelis-Papadopoulos

The purpose of this paper is to propose multigrid methods in conjunction with explicit approximate inverses with various cycles strategies and comparison with the other…

Abstract

Purpose

The purpose of this paper is to propose multigrid methods in conjunction with explicit approximate inverses with various cycles strategies and comparison with the other smoothers.

Design/methodology/approach

The main motive for the derivation of the various multigrid schemes lies in the efficiency of the multigrid methods as well as the explicit approximate inverses. The combination of the various multigrid cycles with the explicit approximate inverses as smoothers in conjunction with the dynamic over/under relaxation (DOUR) algorithm results in efficient schemes for solving large sparse linear systems derived from the discretization of partial differential equations (PDE).

Findings

Application of the proposed multigrid methods on two-dimensional boundary value problems is discussed and numerical results are given concerning the convergence behavior and the convergence factors. The results are comparatively better than the V-cycle multigrid schemes presented in a recent report (Filelis-Papadopoulos and Gravvanis).

Research limitations/implications

The limitations of the proposed scheme lie in the fact that the explicit finite difference approximate inverse matrix used as smoother in the multigrid method is a preconditioner for specific sparsity pattern. Further research is carried out in order to derive a generic explicit approximate inverse for any type of sparsity pattern.

Originality/value

A novel smoother for the geometric multigrid method is proposed, based on optimized banded approximate inverse matrix preconditioner, the Richardson method in conjunction with the DOUR scheme, for solving large sparse linear systems derived from finite difference discretization of PDEs. Moreover, the applicability and convergence behavior of the proposed scheme is examined based on various cycles and comparative results are given against the damped Jacobi smoother.

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Article
Publication date: 1 May 1995

L. Fourment and J.L. Chenot

The analysis of error estimation is addressed in the framework ofviscoplasticity problems, this is to say, of incompressible andnon‐linear materials. Firstly…

Abstract

The analysis of error estimation is addressed in the framework of viscoplasticity problems, this is to say, of incompressible and non‐linear materials. Firstly, Zienkiewicz—Zhu (Z2) type error estimators are studied. They are based on the comparison between the finite element solution and a continuous solution which is computed by smoothing technique. From numerical examples, it is shown that the choice of a finite difference smoothing method (Orkisz’ method) improves the precision and the efficiency of this type of estimator. Then a Δ estimator is introduced. It makes it possible to take into account the fact that the smoothed solution does not verify the balance equations. On the other hand, it leads us to introduce estimators for the velocity error according to the L2 and Lnorms, since in metal forming this error is as important as the energy error. These estimators are applied to an industrial problem of extrusion, demonstrating all the potential of the adaptive remeshing method for forming processes.

Details

Engineering Computations, vol. 12 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 14 March 2019

Lin Fu, Zhe Ji, Xiangyu Y. Hu and Nikolaus A. Adams

This paper aims to develop a parallel fast neighbor search method and communication strategy for particle-based methods with adaptive smoothing-length on…

Abstract

Purpose

This paper aims to develop a parallel fast neighbor search method and communication strategy for particle-based methods with adaptive smoothing-length on distributed-memory computing systems.

Design/methodology/approach

With a multi-resolution-based hierarchical data structure, the parallel neighbor search method is developed to detect and construct ghost buffer particles, i.e. neighboring particles on remote processor nodes. To migrate ghost buffer particles among processor nodes, an undirected graph is established to characterize the sparse data communication relation and is dynamically recomposed. By the introduction of an edge coloring algorithm from graph theory, the complex sparse data exchange can be accomplished within optimized frequency. For each communication substep, only efficient nonblocking point-to-point communication is involved.

Findings

Two demonstration scenarios are considered: fluid dynamics based on smoothed-particle hydrodynamics with adaptive smoothing-length and a recently proposed physics-motivated partitioning method [Fu et al., JCP 341 (2017): 447-473]. Several new concepts are introduced to recast the partitioning method into a parallel version. A set of numerical experiments is conducted to demonstrate the performance and potential of the proposed parallel algorithms.

Originality/value

The proposed methods are simple to implement in large-scale parallel environment and can handle particle simulations with arbitrarily varying smoothing-lengths. The implemented smoothed-particle hydrodynamics solver has good parallel performance, suggesting the potential for other scientific applications.

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Article
Publication date: 1 March 2016

Daniel W. Williams and Shayne C. Kavanagh

This study examines forecast accuracy associated with the forecast of 55 revenue data series of 18 local governments. The last 18 months (6 quarters; or 2 years) of the…

Abstract

This study examines forecast accuracy associated with the forecast of 55 revenue data series of 18 local governments. The last 18 months (6 quarters; or 2 years) of the data are held-out for accuracy evaluation. Results show that forecast software, damped trend methods, and simple exponential smoothing methods perform best with monthly and quarterly data; and use of monthly or quarterly data is marginally better than annualized data. For monthly data, there is no advantage to converting dollar values to real dollars before forecasting and reconverting using a forecasted index. With annual data, naïve methods can outperform exponential smoothing methods for some types of data; and real dollar conversion generally outperforms nominal dollars. The study suggests benchmark forecast errors and recommends a process for selecting a forecast method.

Details

Journal of Public Budgeting, Accounting & Financial Management, vol. 28 no. 4
Type: Research Article
ISSN: 1096-3367

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Article
Publication date: 27 September 2011

Neila Boulila Taktak

The purpose of this paper is to examine empirically the nature of smoothing returns practices in a sample of 79 Islamic banks across 19 countries during the period 2001‐2006.

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Abstract

Purpose

The purpose of this paper is to examine empirically the nature of smoothing returns practices in a sample of 79 Islamic banks across 19 countries during the period 2001‐2006.

Design/methodology/approach

Previous researchers' methods, based on the variation and determination coefficients, are used in this study to detect the smoothing practices.

Findings

Results indicate that the revenues from the “Shariah‐based products” derived from the profit and loss sharing principle show higher variability than the “Shariah compliant revenues” and that income from this source is relatively lower. They also show that a large number of Islamic banks engage in natural income smoothing. Based on the determination coefficient results, 70 per cent of banks were found to have less smoothed total revenue than their net income. Results based on variation coefficient further confirm this finding, with 67 banks having a coefficient of total revenue higher than that of the net income.

Practical implications

The results suggest that Islamic banks should strengthen the use of smoothing techniques, such as the profit equalization reserves (PER) and the investment risk reserves (IRR), as they allow them to further stabilize the revenues payout for the investment account holders (IAH) and therefore mitigate withdrawal risk. Standardizing the smoothing techniques could be a solution to overcome the variability of this category of revenue.

Originality/value

This work is the first of its kind for Islamic banks. It extends previous research by examining whether or not managers may smooth their results naturally or intentionally. It also helped to bridge the gap in the literature by providing the empirical evidence on the smoothing returns in Islamic finance.

Details

Journal of Islamic Accounting and Business Research, vol. 2 no. 2
Type: Research Article
ISSN: 1759-0817

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