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Article
Publication date: 4 January 2016

J. Faiz, H. Ehya, A.M. Takbash, S. Shojaee, M. Hamidian and A. Ghorbani

Electrical energy distribution systems must be low losses systems in order to enhance the system efficiency. Therefore, it is preferred to distribute electrical energy by…

229

Abstract

Purpose

Electrical energy distribution systems must be low losses systems in order to enhance the system efficiency. Therefore, it is preferred to distribute electrical energy by bus-ducts in the place of cables over all energy levels and decrease the losses. The purpose of this paper is to focus on a comprehensive survey of various aspects of bus-ducts design including electromagnetic, mechanical and thermal. Advantages and disadvantages of different available design techniques are reviewed.

Design/methodology/approach

Different works on various bus-based power transmission and distribution systems are reviewed. Generally these are done in three categories including systems modeling methods, heat transfer in the systems, short circuit and electromagnetic force. The attempt is made to provide geometrical and materials specifications in order to present the analyzed system well.

Findings

Different types of bus-ducts from used materials, voltage level and insulation types are reviewed. Bus-duct modeling techniques are introduced which can be easily applied for bus-ducts design. Electromagnetic field distribution, thermal pattern inside and outside of the bus-duct in normal and short circuit modes and finally mechanical considerations are dominant factors which must be taken into account in the bus-ducts design. This leads to an optimal design of bus-ducts which prolong the life span of the bus-ducts fixed in the installations.

Originality/value

This paper for the first time systematically reviews the latest state of arts in the design of bus-ducts for efficient electrical energy distribution. It summarizes a variety of design techniques applicable to bus-ducts design.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 28 March 2019

Jerzy Gołębiowski and Marek Zaręba

The purpose of this paper is to analyse the dynamics of a thermal field generated in a tubular bus with rated current by using two models of electrical resistivity of copper.

80

Abstract

Purpose

The purpose of this paper is to analyse the dynamics of a thermal field generated in a tubular bus with rated current by using two models of electrical resistivity of copper.

Design/methodology/approach

The boundary-initial problem of the modified heat equation was formulated for the tubular bus. Analytical solutions were obtained by means of Green’s functions as the kernels of the integral operator inverse to the corresponding differential operator. The results were presented graphically and verified using the finite element method. The calculations were made by considering the example of the Storm Power Components tubular bus (USA).

Findings

Analytical field models were used to determine time- and space-variable heating curves, time constants and steady-state current ratings.

Research limitations/implications

This paper is related to the structure of a hollow cylinder. Other bus sections can be taken into account by using the coordinate systems of different curvilinear orthogonal symmetry.

Originality/value

Using the analytical method, the influence of the variable (temperature dependent) electrical resistivity on some important parameters and characteristics of the tubular bus was investigated. The system was considered as an element with distributed parameters.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 23 September 2022

Amir Amjad Mohammadi, Hadi Safaeipour, Mohammad Reza Chenaghlou, Alireza Behnejad and Roham Afghani Khoraskani

This paper aims at discovering the traditional techniques of Persian architecture for covering large-span spaces with a kind of ribbed vault titled “Karbandi”. This structure is…

118

Abstract

Purpose

This paper aims at discovering the traditional techniques of Persian architecture for covering large-span spaces with a kind of ribbed vault titled “Karbandi”. This structure is generated by intersecting several arches with a harmonic stellar geometry. Preliminary studies show that span factor affects the structural form of karbandi and large-span cases, despite similar architectural forms, have different structural systems and specific construction methods. The main focus of this paper is how karbandi has been designed and built on large-spans. To answer this question, the configuration and construction of a large-span karbandi in Tabriz Bazaar were recognized.

Design/methodology/approach

Data collection of the research was initially done in three parallel directions through the archival study of restoration documents, direct observation of the corpus of the vaultings and interviews with the master mason of the Haj-Mohammad-Qoli Timche restoration team. Then by cross-referencing the gathered data, the construction process of the karbandi was simulated in Rhino 6 and Grasshoppers software and its BIM-M models were created in three levels of development: LOD300, LOD350 and LOD400. In the next step, the preliminary BIM-M models of the karbandi were presented to the interviewed mason and revised and completed based on his comments.

Findings

Analyzing the BIM models by reverse engineering, resulted in (1) Discovering a unique self-supporting masonry construction method applied for the erection of karbandi vaulting on large-spans. (2) Finding the effect of scale factor on the architectural and structural form of the karbandi vault. (3) Discovering the connection types of the karbandi vault based on the construction details.

Originality/value

Despite the wide applications of karbandi vaults throughout history, very little information of their construction techniques is available. The techniques have mostly been experientially and orally passed down from masters to apprentices and rarely been documented. The quest to design and construct a karbandi vault is therefore like solving a puzzle whose most important guide is historical cases. Due to the geometric complexity of karbandi and its ability to cover large-span spaces, solving the puzzle can lead to achieving some technical ideas for masonry cross-ribbed vaulting. A great riddle of the karbandi vaults is how to design and build them on a large span.

Details

Engineering, Construction and Architectural Management, vol. 31 no. 1
Type: Research Article
ISSN: 0969-9988

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Article
Publication date: 7 November 2016

Manuel Pineda-Sanchez, Angel Sapena-Baño, Juan Perez-Cruz, Javier Martinez-Roman, Ruben Puche-Panadero and Martin Riera-Guasp

Rectangular conductors play an important role in planar transmission line structures, multiconductor transmission lines, in power transmission and distribution systems, LCL…

280

Abstract

Purpose

Rectangular conductors play an important role in planar transmission line structures, multiconductor transmission lines, in power transmission and distribution systems, LCL filters, transformers, industrial busbars, MEMs devices, among many others. The precise determination of the inductance of such conductors is necessary for their design and optimization, but no explicit solution for the AC resistance and internal inductances per-unit length of a linear conductor with a rectangular cross-section has been found, so numerical methods must be used. The purpose of this paper is to introduce the use of a novel numerical technique, the proper generalized decomposition (PGD), for the calculation of DC and AC internal inductances of rectangular conductors.

Design/methodology/approach

The PGD approach is used to obtain numerically the internal inductance of a conductor with circular cross-section and with rectangular cross-section, both under DC and AC conditions, using a separated representation of the magnetic vector potential in a 2D domain. The results are compared with the analytical and approximate expressions available in the technical literature, with an excellent concordance.

Findings

The PGD uses simple one-dimensional meshes, one per dimension, so the use of computational resources is very low, and the simulation speed is very high. Besides, the application of the PGD to conductors with rectangular cross-section is particularly advantageous, because rectangular shapes can be represented with a very few number of independent terms, which makes the code very simple and compact. Finally, a key advantage of the PGD is that some parameters of the numerical model can be considered as additional dimensions. In this paper, the frequency has been considered as an additional dimension, and the internal inductance of a rectangular conductor has been computed for the whole range of frequencies desired using a single numerical simulation.

Research limitations/implications

The proposed approach may be applied to the optimization of electrical conductors used in power systems, to solve EMC problems, to the evaluation of partial inductances of wires, etc. Nevertheless, it cannot be applied, as presented in this work, to 3D complex shapes, as, for example, an arrangement of layers of helically stranded wires.

Originality/value

The PGD is a promising new numerical procedure that has been applied successfully in different fields. In this paper, this novel technique is applied to find the DC and AC internal inductance of a conductor with rectangular cross-section, using very dense and large one-dimensional meshes. The proposed method requires very limited memory resources, is very fast, can be programmed using a very simple code, and gives the value of the AC inductance for a complete range of frequencies in a single simulation. The proposed approach can be extended to arbitrary conductor shapes and complex multiconductor lines to further exploit the advantages of the PGD.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 12 January 2024

Maryam Ebrahimi, Amir Daneshvar and Changiz Valmohammadi

To gain and differentiate competitive advantage, the sustainable service quality is a determining factor that railway companies can use. The purpose of this study is to identify…

206

Abstract

Purpose

To gain and differentiate competitive advantage, the sustainable service quality is a determining factor that railway companies can use. The purpose of this study is to identify both the importance and performance of rail transportation service quality factors in a case study as well as determine the most influential quality features.

Design/methodology/approach

A comprehensive approach namely importance–performance analysis (IPA) technique and decision-making trail and evaluation laboratory (DEMATEL), and interpretive structural modeling (ISM) and Matriced’ Impacts Croisés Multiplication Appliquée á un Classement (MICMAC) techniques was utilized.

Findings

The relative position of each attribute is specified on the IPA matrix proposing four strategies of concentrate here, keep up the good work, low priority and possible overkill. This study reveals that attributes of “the company cares about having a good society” are the most influential factor, and “having good business relations with shareholders” is the most permeable factor. Actually, consumers pay attention to how companies act toward society and maintain communication with shareholders. Through ISM technique and by summing the row and column of the consistency matrix, the attributes were partitioned into four levels. Also, MICMAC analysis identified the four clusters of linkage, independent, autonomous and dependent status of the attributes in terms of the driving power and dependence power.

Research limitations/implications

Due to the nature of single case study methodology, caution should be taken into consideration regarding the generazability of the obtained results.

Originality/value

The hybrid DEMATEL-ISM technique is used to analyze service quality factors in Iran’s transportation industry, which can be utilized in other industries as well as other countries.

Details

Journal of Economic and Administrative Sciences, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2054-6238

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Article
Publication date: 10 November 2022

Mohamad Mehdi Mojahedi Moakhar, Mahmoud Esavi, Amir Khademalizadeh and Fathollah Tari

The purpose of this paper is organized as follows. Section 2 reviews the literature on the subject matter, focusing on western economic literature and the Islamic economic…

337

Abstract

Purpose

The purpose of this paper is organized as follows. Section 2 reviews the literature on the subject matter, focusing on western economic literature and the Islamic economic paradigm, including the Quran, Sunnah, jurisprudence and Islamic philosophy thinking, to illustrate the origins of the Islamic approach to monetary systems. The money interest rate and its studies are explained, and the role of money and credit in the production function is considered. Then, it is shown that money maintains the demand for money in the overlapping generation model, as well as the consumption behavior of households. It is followed by an explanation of general Pareto optimality and the role of the money interest rate in inefficiency and nonoptimality for households and firms. Finally, Section 4 concludes the paper.

Design/methodology/approach

This paper studies the effects of money issuance and bank creation on Pareto optimality. In explaining the origins of the Islamic approach to monetary systems, the literature review, it focuses on western economics’ literature and Islamic economics paradigms such as the Quran, sunnah, jurisprudence and Islamic philosophy thinking. In modeling section, the authors show how banks’ fractional reserve credit is profitable. The authors also examine how the introduction of the money interest rate can change the Pareto optimality. In this regard, the comparison between two situations, namely, financing by the stock of money and borrowing in the credit market, indicates that welfare is reduced by the creation system and is inefficient (or nonoptimal). The result is that no money and no credits are created. The provision of this system compensates money by increasing the real money supply or deflation. To ensure Pareto optimality, it has been proven in the field of microfoundation that there should be no fixed money contracts and no money interest rates. It is necessary that the interest rate on consumption credit is zero or Qarz-al-Hasna is broken. Moreover, profit sharing is offered in the production sector.

Findings

As a result, the authors proved mathematically that the money interest rate must be zero to ensure productivity and Pareto optimality. On the other hand, the introduction of money or credit through loanable money leads to inefficiency, both in production and households and in the general equilibrium. The inflation generated by the credit system stimulates the change in the price level and perpetuates this inefficiency. Thus, if the authors want to return to the optimality condition, the interest rate on consumption credit must be zero or Qarz-al-Hasna is breached. However, the behavior of the fractional banking system and the credit mechanism teaches us that the money interest rate is an integral part of credit and loanable funds. Thus, the elimination of the money interest rate from the banking system without bank creation is implausible. Finally, to ensure Pareto optimality, it has been mathematically proven in the field of microfoundation that there should be no fixed money contracts and no money interest rate. It is necessary that the interest rate on consumption credit is zero, or Qarz-al-Hasna is broken. Moreover, profit sharing is offered in the production sector. The result is that no money and credit are created. The provision of this system compensates money by increasing the real money supply or deflation.

Originality/value

The capitalist theory of the definition of interest plays a decisive role in economic science. In this context, the authors are dealing with different vocabularies and terms for the interest rate. These different vocabularies have their origin in the different economic situations and especially determine the thinking of the schools. Because of the relationship between future and spot, the authors have to transform the variable “level” into the variable “interest rate” in the dynamic space. Finally, the exact explanations for the movement and evaluation of the economy are revealed by the correlation of the different interest rates.

Details

International Journal of Islamic and Middle Eastern Finance and Management, vol. 16 no. 2
Type: Research Article
ISSN: 1753-8394

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Article
Publication date: 13 April 2015

Lutfullah saqib, Mueen Aizaz Zafar, Khurram Khan, Kellie W. Roberts and Aliya Mueen Zafar

This paper aims to study Qard-al-Hasan (QH) (good loan) from the stand point of its possible application to agricultural farming with a view to augmenting the sources of Riba…

1654

Abstract

Purpose

This paper aims to study Qard-al-Hasan (QH) (good loan) from the stand point of its possible application to agricultural farming with a view to augmenting the sources of Riba (interest)-free agricultural financing for Muslim farmers of Islamic countries like Pakistan.

Design/methodology/approach

This paper is a study of QH (good loan) from the stand point of its possible application to agricultural farming with a view to augmenting the sources of Riba (interest)-free agricultural financing for Muslim farmers of Islamic countries like Pakistan.

Findings

The study reports that Riba-free financing is essentially needed by poor Muslim farmers who, owing to prohibition of Riba, do not rely on interest (Riba)-based financing. The study also shows that QH is a viable option for fulfilling this need and is beneficial for the farmers as well as for the Islamic banks or financial institutions.

Research limitations/implications

The case of QH as a potential mode of agricultural financing, as presented in this paper, is based on a theoretical or conceptual framework. The findings need to be further substantiated with empirical evidence. A future study, based on reliable empirical data would certainly add value to the subject.

Originality/value

Islamic banks and financial institutions typically rely on Musharakah (partnership), Murabaha (sale with profit), Ijarah (leasing), Salam (advance payment sale), Istisna’ (manufacturing contract), etc., and they rarely use QH as a mode of financing. Despite its huge utility, QH is practically non-existent in its application as an agricultural financing instrument. This paper presents a case for QH that can be adopted by Islamic banks or financial institutions for provision of the much needed financing for the small farmers of Islamic countries, as well as those living in non-Islamic countries.

Details

Journal of Islamic Accounting and Business Research, vol. 6 no. 1
Type: Research Article
ISSN: 1759-0817

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Article
Publication date: 16 November 2015

Seyed Kazem Sadr

The purpose of this paper is to provide explanation for the economic development of the earliest Islamic state. It focuses on the role of human capital as the most important…

1922

Abstract

Purpose

The purpose of this paper is to provide explanation for the economic development of the earliest Islamic state. It focuses on the role of human capital as the most important element of this model and focuses on four dimensions of development of human personality in Islam: the incentive structure, rules of behavior, institutions and policies.

Design/methodology/approach

A review and analysis of the measures and policies that Prophet of Islam and his successors adopted are made to arrive at the underlying economic model of development.

Findings

The major finding is the role of human capital in the development of the economy at that time.

Originality/value

The contribution of the paper is to identify the critical role of education and skills for the development of the economy at present.

Details

International Journal of Islamic and Middle Eastern Finance and Management, vol. 8 no. 4
Type: Research Article
ISSN: 1753-8394

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