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Article
Publication date: 2 March 2012

Fikri Serdar Gokhan and Gunes Yilmaz

The aim of the paper is to demonstrate a fast numerical solution for Raman fiber amplifier equations using proposed guess functions and MATLAB intrinsic properties. MATLAB…

Abstract

Purpose

The aim of the paper is to demonstrate a fast numerical solution for Raman fiber amplifier equations using proposed guess functions and MATLAB intrinsic properties. MATLAB BVP solvers are addressed for the solution.

Design/methodology/approach

The guess functions proposed for the solution of RFA equations using MATLAB BVP solvers are derived from Taylor expansion of pump and signal wave near the boundary to specifically obtain convergence for the initial mesh point. The guess functions increase simulation speed significantly. In order to improve the simulation speed further, vectorization and analytical Jacobians are introduced. Comparisons among bvp4c and bvp5c have been made with respect to total pump power, number of signals, vectorization with/without analytical Jacobians, fiber length, relative tolerance and continuation method. The simulations are performed to determine the effect of the run time on the choice of the number of equally spaced mesh points (N) in the initial guess, and thus optimal N values are found.

Findings

MATLAB BVP solvers have been proven to be effective for the numerical solution of RFAs with the proposed guess functions. In particular, with vectorizing, run time reduction is between 2.1 and 5.4 times for bvp4c and between 1.6 and 2.1 times for bvp5c and in addition to vectorizing, with the introduction of the analytical Jacobians, the reduction is between 2.4 and 6.2 times for bvp4c and 1.7 and 2.2 times for bvp5c, respectively, depending on the total pump power between 1,000 mW and 2,000 mW and the number of signals. Also, simulation results show that the efficiency of the solution with proposed guess functions is improved more than six times compared with those of previously reported continuation methods. Results show that the proposed guess functions with the vectorization and analytical Jacobians can be used for the performance evaluation of RFAs for the high power systems/long gain fiber span.

Practical implications

The robust improvement of the solution proposed in this paper lies in the fact that the derived guess functions for the RFAs are highly effective in the sense that they assist the solver to converge to the solution for any total pump power value in a wide range from 1 to 3,000 mW and for any fiber lengths ranging 1 to 200 km which are used in practical applications. Hence, it is practicable for the performance evaluation of the existing RFA networks.

Originality/value

The novelty of this method is that, starting with the co‐propagating single pump and signal RFA schema, the authors derived the guess function specifically for the initial mesh points rather than using its analytical approximations. Moreover, the solution is generalized for co‐/counter propagating pumps/signals with the curve fitted coefficient(s).

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 8 March 2011

Fikri Serdar Gokhan and Gunes Yilmaz

The purpose of this paper is to demonstrate an effective and robust numerical solution for Raman fiber amplifier (RFA) equations which have no explicit solution. MATLAB…

Abstract

Purpose

The purpose of this paper is to demonstrate an effective and robust numerical solution for Raman fiber amplifier (RFA) equations which have no explicit solution. MATLAB BVP solvers are addressed for the solution.

Design/methodology/approach

The continuation method proposed for the solution of RFA equations using MATLAB BVP solvers is explained. Scripts for improving the power values at the boundaries with continuation, extending fiber length with continuation and calculation of the analytical partial derivatives using the MATLAB Symbolic toolbox are introduced. Comparisons among the different MATLAB BVP solvers have been made. Using the continuation method, signal evolutions for different kinds of RFA amplifier configurations are plotted.

Findings

The paper finds that MATLAB BVP solver with the continuation method can be used in the design of various kinds of RFAs for high powers/long gain fiber spans.

Research limitations/implications

The paper will assist the fiber optic research community who suffer from two or more point boundary‐value problems. Moreover, the stiffness of the signal evolution which is faced with high pump powers and/or long fiber lengths can be solved with continuation. This superiority of the solver can be used to overcome any stiff changes of the signals for future studies.

Practical implications

The increased research interests and practical demands for RFAs have been calling for reasonable and efficient means for the performance evaluation of RFAs before the real amplifiers are fabricated. The solution method presented in this paper will be an efficient means for the solution of this issue.

Originality/value

MATLAB BVP solvers have been proven to be effective for the numerical solution of RFAs with multiple pumps and signal waves. Using the continuation method, in a distributed RFA with ten pump sources, 2,400 mW total input pump power is achieved. The improvement of the total power is about 1.4 times compared with those of the previously reported methods. Using the MATLAB BVP solvers, total power/fiber span can be improved further using the continuation process with the cost of computational time. This is a notable and promising improvement from a RFA designer's point of view.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 11 May 2010

Fikri Serdar Gokhan and Gunes Yilmaz

The purpose of this paper is to demonstrate an effective and faster numerical solution for nonlinear‐coupled differential equations describing fiber amplifiers which have…

Abstract

Purpose

The purpose of this paper is to demonstrate an effective and faster numerical solution for nonlinear‐coupled differential equations describing fiber amplifiers which have no explicit solution. MATLAB boundary value problem (BVP) solver of bvp6c function is addressed for the solution.

Design/methodology/approach

Coding method with the bvp6c is introduced, signal evolution, threshold calculation method is introduced, gain and noise figure are plotted and superiority of the bvp6c solver is compared with the Newton‐Raphson method.

Findings

bvp6c function appears to be an effective tool for the solution fiber amplifier equations and can be used for different pump configurations of BFAs and RFAs. The excellent agreement between the proposed and reported results shows the reliability of the proposed threshold power calculation method.

Research limitations/implications

The paper eases the work of the fiber optic research community, who suffer from two point BVPs. Moreover, the stiffness of the signal evolution which is faced with high pump powers and/or long fiber lengths can be solved with continuation. This superiority of the solver can be used to overcome any stiff changes of the signals for the future studies.

Practical implications

The main outcome of this paper is the numerically calculation of the threshold values of fiber amplifiers without the necessity of the experiment. The robustness improvement of the solution is that the solver is able to solve the equations even with the poor guess values and the solution can be obtained without the necessity of analytical Jacobian matrix.

Originality/value

MATLAB bvp6c solver has proven to be effective for the numerical solution of nonlinear‐coupled intensity differential equations describing fiber amplifiers with two‐point boundary values. Beside the signal evolution, thresholds of Brillouin and Raman fiber amplifiers can also be calculated by using the proposed solver. This is a notable and promising improvement of the paper, at least from a fiber optic amplifier designer point of view.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Content available
Article
Publication date: 6 August 2018

Fekri Ali Shawtari, Milad Abdelnabi Salem and Izzeldin Bakhit

The purpose of this paper is to examine empirically the efficiency types of Islamic and conventional banks. It seeks to show whether the efficiency level of conventional…

Abstract

Purpose

The purpose of this paper is to examine empirically the efficiency types of Islamic and conventional banks. It seeks to show whether the efficiency level of conventional and Islamic banks significantly differs from each other. In addition, it investigates the influential factors on each type of efficiency.

Design/methodology/approach

The paper utilises the data envelopment analysis in its windows version to estimate the efficiency scores reflecting the time variance and compares between banking models. The paper uses pure technical efficiency (TE) and scale efficiency to achieve the objective of the study. In addition, the panel data technique is adopted to assess the determinants of the efficiency of the banks econometrically.

Findings

The findings of panel regression initially indicate that the pure TE is higher for conventional banks compared to Islamic banks. However, the Islamic banks are more scale efficient than their conventional counterpart. Macro and micro indicators have different impacts on the both types of efficiency. However, the unique factors that show consistent influence on the efficiency types were loans/finance, non-interest income/finance/liquidity and GDP. Furthermore, the determinants are shaped differently for Islamic and conventional banks when the banking model is controlled for.

Originality/value

This paper examines the efficiency types using a unique window analysis approach to examine the types of efficiency with a longitudinal set of data from 1996 to 2011.

Details

Benchmarking: An International Journal, vol. 25 no. 6
Type: Research Article
ISSN: 1463-5771

Keywords

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Article
Publication date: 16 July 2019

Kemal Yıldırım, Elif Güneş and Gülcan Pervan Yilmaz

The purpose of this paper is to determine the effects of environmental factors in open-plan offices with the same characteristics but with different workstation partition…

Abstract

Purpose

The purpose of this paper is to determine the effects of environmental factors in open-plan offices with the same characteristics but with different workstation partition heights (1.10, 1.40 and 1.65 m) on perceptual evaluations of office employees.

Design/methodology/approach

In this research, the effects of environmental factors on employees’ perceptual evaluations in open-plan offices at the Gölbaşı Region of Ankara were measured with a detailed questionnaire. The research data were obtained from 81 employees who agreed to fill out the questionnaire and who use open-plan offices.

Findings

It was found that the office environments with 1.65 m workstation partition heights were more favorably assessed for each of the items of planning and of privacy that form the dependent variables compared to the office environments with 1.10  and 1.40 m partition heights. On the other hand, the office environments with the 1.10 and 1.40 m partition heights were more favorable for lighting items than the 1.65 m partition height office environments. In addition, young employees had a more positive tendency toward the perceptions of environmental factors, including different workstation partition heights in open-plan offices, compared to older employees.

Research limitations/implications

Results of this research provide a fundamental contribution for the impact of various partition heights that have substantial implications on the perceptions of open-plan office environments. At this point, as open-plan offices have important effects on the quality of employees’ work experiences, the influence of various partition heights on the performance of employees should be emphasized in future studies. The diversity of performance (reading comprehension, calculation, design, drawing, etc.) will be an important decision.

Originality/value

The significant contribution of this research is that it provides valid data and makes a valuable contribution to the body of knowledge in open-plan office design.

Details

Journal of Corporate Real Estate , vol. 21 no. 2
Type: Research Article
ISSN: 1463-001X

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Article
Publication date: 8 August 2016

Vincenza Capone and Giovanna Petrillo

The purpose of this paper is to contribute to the validation of the Organizational Justice Index (OJI) by Hoy and Tarter (2004), a self-report questionnaire for teachers…

Abstract

Purpose

The purpose of this paper is to contribute to the validation of the Organizational Justice Index (OJI) by Hoy and Tarter (2004), a self-report questionnaire for teachers’ perceptions of fairness in the operation and administration of schools.

Design/methodology/approach

In two studies the authors validated the Italian version of the OJI. Study 1 included 164 Italian high school teachers (76.8 percent were female) to test structure and construct validity. Study 2 involved 200 teachers (permanent and temporary teachers) to confirm the structure of the scale, test the construct and criterion validity, and invariance.

Findings

Confirmatory factor analyses confirmed the one-factor solution and that the structure of the scale was the same across teachers. Results revealed high internal reliability. The OJI correlated positively with equity, school climate, and job satisfaction, and negatively with depression and burnout.

Research limitations/implications

Since the research approach could lead to common method variance issues, it will be important to determine the associations of OJI with non-self-report assessments.

Practical implications

The OJI can be applied optimally to: assess potential organizational problems prior to conducting major interventions; investigate school dynamic problems; target interventions designed to enhance perception of organizational justice; incorporate evaluation of organizational justice as part of regular employee assessments.

Originality/value

Overall findings fill the need of standardized measures of organizational justice for specific context. The OJI is a valid instrument to measure organizational justice in school, involving different type of teachers.

Details

International Journal of Educational Management, vol. 30 no. 6
Type: Research Article
ISSN: 0951-354X

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Article
Publication date: 10 December 2019

Ayse Kucuk Yilmaz

Each decision-making involves risk; therefore, risk is a strategic element in management and organization. In terms of risk management, the transformation process in…

Abstract

Purpose

Each decision-making involves risk; therefore, risk is a strategic element in management and organization. In terms of risk management, the transformation process in organizations should be aimed at optimizing and improving the most important performance criteria such as cost, quality, flexibility and speed, rather than just as required by legislation. Transformation process has sustainability risks for organizations. ATO transformation process should be well designed. Process also should include clear steps to implement them. Sound and well-designed process will be useful for organizational performance and quality management. The management of the risks of conversion processes is vital for the continuation of operations without interruption. In aviation universities’ approved training organizations (ATOs), each system must be handled and processed separately. Transformation plans should be prepared considering the risks of each system. The purpose of this study is to develop process flowcharts of all systems in sustainable ATO transformation process from risk management perspective.

Design/methodology/approach

Flowchart method is useful to identify process risks in organizational system transformation. Flowcharts simplify communication and provide effective analysis of the process. Flowchart enables designing plan which is suitable for aimed results. Flowcharts method provides efficient coding and system analysis and program development phase also serves as a guide while debugging errors. In this study, flowcharts including all stages have been developed for transition to an ATO authorization. With these flowcharts, all elements of the process and the risks, threats and opportunities that may be faced can be proactively identified together. Thus, improvements will be possible to achieve the corporate objectives of the transformation and reorganization process and increase the corporate performance with optimum resource usage.

Findings

Flowcharts may contribute to the reorganization and transformation of processes in all aviation academies. In this sense, it provides infrastructure for future studies. New studies can be carried out for the reorganization of all departments in aviation. It is believed that this research will contribute to the aviation management literature. Flowchart is also called as process flowchart or process flow diagram. Flowchart is effective methodology to manage transformation process risk. Owing to clarify each step in transformation process, risks may be managed with timely decision-making by managers. In this research, five fundamental flowcharts have been developed in ATO system. These include all processes in transformation as preparation of manuals, new authority application, competent authority inspections, corrective and preventive actions, revalidation and fees in transformation process and its parts. Presented flowcharts may be useful to identify and manage process risk in initial phase as consent with proactive management style.

Research limitations/implications

This research presents designed flowcharts for ATO transformation risk management process. This research may extend at other departments in aviation universities such as air traffic control, maintenance and management.

Practical implications

As a methodology, flowcharts can be considered as schematic algorithms. The flowchart is a detailed representation of the process to carry out a specific task. In this research, flowcharts have been developed for transformation process stages at ATO authorization. These flowcharts are useful for proactive identification of process elements and their risks – threats and opportunities. Thus, improvements will be possible to achieve the corporate objectives of the transformation and reorganization process and increase the corporate performance with optimum resource usage. Flowcharts may contribute to the reorganization and transformation of processes in all aviation academies. In this sense, it provides infrastructure for future studies. New studies can be carried out for the reorganization of all departments in aviation. It is believed that this research will contribute to the management and strategy literature with engineering.

Originality/value

ATO transformation process risk management has not been studied much in literature. The operational manuals of ATO's management and strategy planning prepare according to both legal regulations and handbooks of aviation authorities which obliged for ATO. It is anticipated that this original study may be useful for determining the risks of transformation processes of flight training departments of civil aviation universities and for good process design. Flowcharts may contribute to the reorganization and transformation of processes in all aviation academies. In this sense, this study provides infrastructure for future studies. New studies can be carried out for the reorganization of all departments in aviation. It is believed that this research will contribute to the aviation management literature. Flowchart is also called as process flowchart or process flow diagram. Flowchart is effective methodology to manage transformation process risk. Owing to clarify each step in transformation process, risks may be managed with timely decision-making by managers. The aviation universities operate with authorization. This research may contribute to their process management and strategy to complete their transformation and transition via risk management. Developed flowcharts present all necessary steps to become authorized as an ATO. This research may serve as a kind of framework guide for other aviation organizations to be used in their transformation/transition process.

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Article
Publication date: 4 May 2020

Fatma Altuntas and Mehmet Şahin Gök

The purpose of this paper is to analyze the wind energy technologies using the social network analysis based on patent information. Analysis of patent documents with…

Abstract

Purpose

The purpose of this paper is to analyze the wind energy technologies using the social network analysis based on patent information. Analysis of patent documents with social network analysis is used to identify the most influential and connected technologies in the field of wind energy.

Design/methodology/approach

In the literature, patent data are often used to evaluate technologies. Patents related to wind energy technologies are obtained from the United States Patent and Trademark Office database and the relationships among sub-technologies based on Corporate Patent Classification (CPC) codes are analyzed in this study. The results of two-phase algorithm for mining high average-utility itemsets algorithm, which is one of the utility mining algorithm in data mining, is used to find associations among wind energy technologies for social network analysis.

Findings

The results of this study show that it is very important to focus on wind motors and technologies related to energy conversion or management systems reducing greenhouse gas emissions. The results of this study imply that Y02E, F03D and F05B CPC codes are the most influential CPC codes based on social network analysis.

Originality/value

Analysis of patent documents with social network analysis for technology evaluation is extremely limited in the literature. There is no research related to the analysis of patent documents with social network analysis, in particular CPC codes, for wind energy technology. This paper fills this gap in the literature. This study explores technologies related to wind energy technologies and identifies the most influential wind energy technologies in practice. This study also extracts useful information and knowledge to identify core corporate patent class (es) in the field of wind energy technology.

Details

Kybernetes, vol. 50 no. 5
Type: Research Article
ISSN: 0368-492X

Keywords

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Article
Publication date: 24 September 2019

Madjid Tavana and Vahid Hajipour

Expert systems are computer-based systems that mimic the logical processes of human experts or organizations to give advice in a specific domain of knowledge. Fuzzy expert…

Abstract

Purpose

Expert systems are computer-based systems that mimic the logical processes of human experts or organizations to give advice in a specific domain of knowledge. Fuzzy expert systems use fuzzy logic to handle uncertainties generated by imprecise, incomplete and/or vague information. The purpose of this paper is to present a comprehensive review of the methods and applications in fuzzy expert systems.

Design/methodology/approach

The authors have carefully reviewed 281 journal publications and 149 conference proceedings published over the past 37 years since 1982. The authors grouped the journal publications and conference proceedings separately accordingly to the methods, application domains, tools and inference systems.

Findings

The authors have synthesized the findings and proposed useful suggestions for future research directions. The authors show that the most common use of fuzzy expert systems is in the medical field.

Originality/value

Fuzzy logic can be used to manage uncertainty in expert systems and solve problems that cannot be solved effectively with conventional methods. In this study, the authors present a comprehensive review of the methods and applications in fuzzy expert systems which could be useful for practicing managers developing expert systems under uncertainty.

Details

Benchmarking: An International Journal, vol. 27 no. 1
Type: Research Article
ISSN: 1463-5771

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Article
Publication date: 27 July 2020

Fatma Kürüm Varolgüneş

In this study, the effects of permanent housing (PH) practices carried out after an earthquake in Turkey were investigated with a case study. Determining the factors that…

Abstract

Purpose

In this study, the effects of permanent housing (PH) practices carried out after an earthquake in Turkey were investigated with a case study. Determining the factors that increase occupants’ satisfaction at the local level and transferring them to the projects to be conducted were aimed.

Design/methodology/approach

The data obtained with questionnaires, statistical analyses, drawings and area examinations belonging to the PH areas built after the 2003 Bingöl earthquake were based on a complementary qualitative research study. Exploratory (EFA) and confirmatory factor analyses (CFA) were used in the analysis of the data. In the CFA, various fits or conformity indices were used to determine to what extent the suggested models showed compliance with the data. SPSS and AMOS were preferred as analysis software.

Findings

When the findings were examined, it was observed that there are significant deficiencies in the activities regarding planning and carrying out the PH production process after the 2003 Bingöl earthquake. An analysis to determine success factors revealed that the most important factor affecting satisfaction is “housing environment.” In addition, the factors “housing design,” “economic recovery,” “cooperation,” “built quality” and “social effect” were determined as important elements for successful results.

Research limitations/implications

The most important way to reduce the destructive effects of disasters is to develop correct solutions. Therefore, it is of great importance to conduct research in an earthquake-affected region, to examine the performance of the produced environments, to present the existing problems and to determine the satisfaction of the users in the new housing and their environment.

Originality/value

This study raises awareness of the importance of creating living spaces that respond to the needs of victims in order to reduce social, physiological and psychological risks in PH applications after the earthquake.

Details

Disaster Prevention and Management: An International Journal, vol. 30 no. 2
Type: Research Article
ISSN: 0965-3562

Keywords

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