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Article

A. Mitter, J.P. Malhotra and H.T. Jadeja

A modelling approach of gas solid flow, considering different physical phenomenon such as fluid turbulence, particle turbulence and interparticle collision effects are…

Abstract

A modelling approach of gas solid flow, considering different physical phenomenon such as fluid turbulence, particle turbulence and interparticle collision effects are presented. The approach is based on the two‐fluid model formulation where both phases are treated as continuum. This implies that the gas phase as well as the particle phase are weighted by their separate volumetric fractions. According to the experimental results and numerical simulations, the inter‐particle collision possesses a significant influence of turbulence level on particle transport properties in gas solid turbulent flow even for dispersed phase volume fraction (α<0.01). Comparisons in predictions have been depicted with inclusion of interparticle collision effect in the equation of particle turbulent kinetic energy and with exclusion of this effect. Experimental research has been conducted in a thermal power plant depicting higher erosion resistance of noncircular square sectioned coal pipe bends in comparison with those with circular cross section, the salient features of the experimental work are presented in this paper. Experiments have been conducted to determine, pressure drop in straight and curved portions of conduits conveying air coal mixtures in a thermal power plant. Validation of this experimental data with numerical predictions have been presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 14 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Book part

Marc Wouters, Susana Morales, Sven Grollmuss and Michael Scheer

The paper provides an overview of research published in the innovation and operations management (IOM) literature on 15 methods for cost management in new product…

Abstract

Purpose

The paper provides an overview of research published in the innovation and operations management (IOM) literature on 15 methods for cost management in new product development, and it provides a comparison to an earlier review of the management accounting (MA) literature (Wouters & Morales, 2014).

Methodology/approach

This structured literature search covers papers published in 23 journals in IOM in the period 1990–2014.

Findings

The search yielded a sample of 208 unique papers with 275 results (one paper could refer to multiple cost management methods). The top 3 methods are modular design, component commonality, and product platforms, with 115 results (42%) together. In the MA literature, these three methods accounted for 29%, but target costing was the most researched cost management method by far (26%). Simulation is the most frequently used research method in the IOM literature, whereas this was averagely used in the MA literature; qualitative studies were the most frequently used research method in the MA literature, whereas this was averagely used in the IOM literature. We found a lot of papers presenting practical approaches or decision models as a further development of a particular cost management method, which is a clear difference from the MA literature.

Research limitations/implications

This review focused on the same cost management methods, and future research could also consider other cost management methods which are likely to be more important in the IOM literature compared to the MA literature. Future research could also investigate innovative cost management practices in more detail through longitudinal case studies.

Originality/value

This review of research on methods for cost management published outside the MA literature provides an overview for MA researchers. It highlights key differences between both literatures in their research of the same cost management methods.

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Article

M.K.M. Ho, G.H. Yeoh and J.Y. Tu

This study aims to examine both the population balance approach based on the MUltiple SIze Group (MUSIG) model and the average bubble number density transport equation…

Abstract

Purpose

This study aims to examine both the population balance approach based on the MUltiple SIze Group (MUSIG) model and the average bubble number density transport equation (ABND) model for 3D, low pressure, gas‐liquid, subcooled boiling, vertical flows. The purpose is to assess the ability of both models to predict the radial profile of void fraction, bubble Sauter mean diameter and interfacial area concentration which characterise subcooled boiling.

Design/methodology/approach

Improvement in the ABND model to simulate gas‐liquid bubbly flows with heat transfer was achieved by combining the condensation expression with the gaseous mass transport equation within the CFD commercial code CFX4.4.

Findings

Overall, both the ABND model and the MUSIG model provided good results in terms of the above‐mentioned criteria when compared against experimental measurements. However, the ABND model was found to have limitations in predicting high‐subcooled boiling flows due to the lack of bubble size resolution to adequately capture the effect of condensation over a range of bubbles sizes.

Originality/value

It is shown that the ABND model provides an economic alternative to the MUSIG model in terms of complexity and computational time, as long as one is aware of the limitations in simulating high‐subcooling flow regimes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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Article

Jun Tu, Tao Chen, Zhi Xiong, Xiaochun Song and Songling Huang

The aim of this paper is to better understand the generation and transmission mechanism of the electromagnetic acoustic transducer (EMAT).

Abstract

Purpose

The aim of this paper is to better understand the generation and transmission mechanism of the electromagnetic acoustic transducer (EMAT).

Design/methodology/approach

A semi-analytical method was used to calculate the Lorentz force. Both the hypothetical magnetic field mirror method and the diffusion equation were adopted to solve the eddy current distribution by variables separation method in time domain. A three-dimension magnetostatic finite element model was used to calculate the static magnetic field and the relative permeability. And an experimental platform with a piezoelectric probe to generate and an EMAT to receive, the ultrasonic wave was set up to verify the distribution of the Lorentz force.

Findings

The Lorentz force at different time and in different positions of the steel plate can be easily calculated. The experimental results show a good agreement with the analytical results.

Originality/value

The accurate prediction of the Lorentz force provides an insight into the physical phenomenon of EMAT and a powerful tool to design optimum EMAT.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Yanping Li, Diwan Li, Yidong Tu and Jie Liu

The purpose of this paper is to investigate the relationship between servant leadership and life satisfaction through the mediating role of workplace positive affect…

Abstract

Purpose

The purpose of this paper is to investigate the relationship between servant leadership and life satisfaction through the mediating role of workplace positive affect (WPA), and the moderating roles of collectivistic orientation and general self-efficacy.

Design/methodology/approach

Using a sample of 304 employees in a two-wave survey, the hypotheses were demonstrated with hierarchical regression analyses.

Findings

The results revealed that servant leadership was positively related to employee life satisfaction, and WPA served as a mediator between them. Moreover, collectivistic orientation and general self-efficacy moderated the relationship between servant leadership and WPA, and the indirect effect of servant leadership on life satisfaction via WPA.

Research limitations/implications

The time-lagged research design of this study may limit the ability to draw causal conclusions. Moreover, as this research was conducted in a Chinese context, the question of the generalizability of our findings calls for more attention.

Practical implications

Leaders are encouraged to adopt the servant leadership style to facilitate employee life satisfaction and organizations should select and recruit managers with servant leadership qualities. Furthermore, because employees’ collectivistic orientation and general self-efficacy moderate the effects of servant leadership on followers’ outcomes, managers need to take individual differences into consideration when they implement managerial strategy.

Originality/value

This research contributed to a burgeoning stream of servant leadership literature by investigating the functions of servant leadership in promoting life satisfaction, and exploring the affective mechanism linking servant leadership and life satisfaction as well as the boundary conditions of collectivistic orientation and general self-efficacy.

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Article

Zhihuai Xiao, Jiang Guo, Hongtao Zeng, Pan Zhou and Shuqing Wang

The purpose of this paper is to develop a new hybridized controller based on fuzzy reasoning and neural network (NN) for hydropower generator unit (HGU).

Abstract

Purpose

The purpose of this paper is to develop a new hybridized controller based on fuzzy reasoning and neural network (NN) for hydropower generator unit (HGU).

Design/methodology/approach

The approach contains fuzzy neural networks controller (FNNC), RBF network identification (RBFNI) and HGU system. FNNC may give control value to control HGU via fuzzy NN reasoning and computing according to HGU rotate speed error and error varying rate. RBFNI is used to identify the character of HGU system and predict its output. FNNC may adjust parameters and member function according to the identifying and predictive outcome of RBFNI.

Findings

Sees that the hybridized control system is feasible and stable, and the controlling performance of the hybridized system is superior to conventional fuzzy controller.

Research limitations/implications

The theoretical proof of stability of the proposed scheme still remains to be studied. Accessibility and availability of membership functions and control rules is also a limitation applied.

Practical implications

The main advantage of the proposed method is that FNNC has reasoning, learning, and optimizing capability which can control effectively HGU. This will be useful for control engineers to control complex industrial plants.

Originality/value

The paper proposes new combined approach to optimal control of HGU using FNNC, and it is aimed at operational researches and engineers, especially those who dealt with HUG controller.

Details

Kybernetes, vol. 38 no. 10
Type: Research Article
ISSN: 0368-492X

Keywords

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Article

Arya Sohrabi, Mir Saman Pishvaee, Ashkan Hafezalkotob and Shahrooz Bamdad

Prepaid mobile Internet is one of the most profitable services that are composed of multiple attributes. The overall utility of Internet service can be broken down into…

Abstract

Purpose

Prepaid mobile Internet is one of the most profitable services that are composed of multiple attributes. The overall utility of Internet service can be broken down into the sum of the utility of individual attribute levels. Based on the multi-attribute theory, rational consumers choose the service that yields the highest utility from a number of possible alternatives. Determining the optimal attribute levels that satisfy consumers' preferences and maximize the total revenue of the firm is a challenging multi-attribute decision problem for any mobile operator. When designing mobile Internet services, adopting a robust composition of services against different realizations of competitors' strategies can bring advantages for network operators. The purpose of this study is to determine the optimal attribute levels of prepaid mobile Internet packages with the aim of maximizing the total revenue of the firm by considering the paradigms of multi-attribute utility theory about consumer choices and the issue of uncertainty in counterpart services offered by the competitors.

Design/methodology/approach

This paper formulates the problem of multi-attribute pricing and design of mobile Internet plans in a competitive environment by developing deterministic and robust scenario-based mathematical models and considering the paradigms of multi-attribute utility theory about consumer choices. The proposed robust scenario-based models are based on three different paradigms, including maximizing expected revenue, minimizing the negative deviation from expected revenue and minimizing the maximum regret. A comprehensive numerical analysis is conducted to evaluate and compare the efficiency of the proposed models.

Findings

The evaluations reveal that deploying recourse policy can result in higher revenue for the firm when facing uncertainty. By doing sensitivity analysis, this paper shows that consumer preferences for brand attribute and consumers' purchase frequency can influence the revenue of network operators.

Originality/value

This paper develops a novel deterministic multi-attribute product line design (PLD) model to address the problem of determining the price and composition of prepaid mobile Internet plans. Furthermore, the issue of uncertainty in counterpart services offered by the competitors is studied for the first time in the PLD literature.

Details

Journal of Enterprise Information Management, vol. 33 no. 5
Type: Research Article
ISSN: 1741-0398

Keywords

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Article

Paul Stark and Udo Fritsching

The purpose of this paper is to develop a numerical model to simulate the flow field as well as the conjugate heat transfer during unsteady cooling of a flat plate with a…

Abstract

Purpose

The purpose of this paper is to develop a numerical model to simulate the flow field as well as the conjugate heat transfer during unsteady cooling of a flat plate with a single submerged water jet. At wall temperatures above the liquid boiling point, the vapor formation process and the interaction of the vapor phase with the developing jet-flow field are included.

Design/methodology/approach

The time-dependent flow and temperature distribution during all occurring boiling phases as well as the local and temporal distribution of the heat transfer coefficient on a flat plate can be simulated.

Findings

The influence of the liquid jet flow rate (10,800=Re_d=32,400) and the nozzle distance to the plate (4=H/d=20) on the transient cooling process are analyzed. This includes the time-dependant positions of the transition regions between the boiling phases on the plate as well as the temperatures at these transition regions. Additionally, the local heat transfer rates are a direct result of the unsteady cooling simulation.

Originality/value

A single model approach is developed and utilized to simulate the unsteady cooling process of a flat plate with an impinging water jet including all occurring boiling phases.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 25 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article

Leon Li and Nen-Chen Richard Hwang

The purpose of this paper is to postulate that market participants’ views on the nature of discretionary accruals as earnings management or earnings manipulation could…

Abstract

Purpose

The purpose of this paper is to postulate that market participants’ views on the nature of discretionary accruals as earnings management or earnings manipulation could relate to a rise or a fall in a firm’s stock prices.

Design/methodology/approach

Applying the quantile regression and measuring gains and losses according to the stock returns, this study shows that the relation between earnings manipulation and stock returns is non-uniform and it varies significantly across various quantiles of the latter.

Findings

The empirical results imply a positive (negative) |DA|-RETURN relation for stocks experiencing a rise (fall) in stock prices. This finding is consistent with the notion that market participants lean towards (become) trend followers (fundamentalists) when their stocks price rise (fall) and, thus, positively reward (negatively punish) discretionary accruals.

Originality/value

Using the behavioural heterogeneity of market participants as a research framework, this paper contributes to the literature by demonstrating that market participants’ decisions to positively reward (negatively punish) earning management behaviour depend on their perceptions on nature of discretionary accruals (earnings management vs earnings manipulation).

Details

Managerial Finance, vol. 45 no. 1
Type: Research Article
ISSN: 0307-4358

Keywords

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Article

Horng‐Wen Wu and Shiang‐Wuu Perng

An axisymmetric two‐dimensional computer program employing the Large Eddy Simulation (LES) and SIMPLE‐C method coupled with preconditioned conjugate gradient methods is…

Abstract

An axisymmetric two‐dimensional computer program employing the Large Eddy Simulation (LES) and SIMPLE‐C method coupled with preconditioned conjugate gradient methods is applied to the turbulent flows in the compression‐expansion strokes for various combustion chamber geometries under realistic engine conditions. The squish area percent of piston crown is changed (SQ = 0 percent for flat piston model, SQ = 46 percent for shallow bowl piston model and SQ = 76 percent for deep bowl piston model) under engine speeds (500∼1,500rpm) for the purpose of investigating the heat transfer performance. Comparison was made of present heat flux results and earlier experimental and numerical results. It is shown that the numerical method can predict the turbulence with reasonable accuracy. The results show that the configuration of piston crown for squish area percent can obviously enlarge the surface heat flux of wall boundaries in reciprocating engines.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 11 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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