bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards a transformer transient model as a lumped-distributed parameter system
Authors: Zirka Sergey E. , Moroz Yuriy I. , Rahimpour Ebrahim 
Published: March 2017

Purpose
The purpose of this study is to develop a topological model of a three-phase, three-limb transformer for low-frequency transients. The processes in the core limbs and yokes are reproduced individually by means of a dynamic hysteresis model (DHM). A method of accounting for the transformer tank with vertical magnetic shunts at the tank walls is proposed and tested on a 120 MVA power transformer.

Design/methodology/approach
The model proposed has been implemented independently in a dedicated Fortran program and in the graphical pre-processor ATPDraw to the ATP version of the electromagnetic transient program.

Findings
It was found that the loss prediction in a wide range of terminal voltages can only be achieved using a DHM with variable excess field component. The zero sequence properties of the transformer can be accurately reproduced by a duality-derived model with Cauer circuits representing tank wall sections (belts).

Research limitations/implications
In its present form, the model proposed is suitable for low-frequency studies. Its usage in the case when transformer capacitances are involved should be studied additionally.

Practical/implications
The presented model can be used either as an independent tool or serve as a reference for subsequent simplifications.

Social/implications
The model proposed is aimed at meeting the needs of electrical engineering and ecology-minded customers.

Originality/value
Till date, there were no experimental data on zero-sequence behavior of three-phase, three-limb transformer with vertical magnetic shunts, so no verified transient model existed. The model proposed is probably the first that matched this behavior and reproduced measured no-load losses for a wide voltage range.
Infinite-time linear–quadratic optimal control of the BLDC motor exploiting a nonlinear finite element model
Authors: Bernat Jakub , Stepien Slawomir Jan , Stranz Artur , Superczynska Paulina 
Published: March 2017

Purpose
This paper aims to present a nonlinear finite element model (FEM) of the Brushless DC (BLDC) motor and the application of the optimal linear–quadratic control-based method to determine the excitation voltage and current waveform considering the minimization of the energy injected to the input circuit and energy lost. The control problem is designed and analyzed using the feedback gain strategy for the infinite time horizon problem.

Design/methodology/approach
The method exploits the distributed parameters, nonlinear FEM of the device. First, dynamic equations of the BLDC motor are transformed into a suitable form that makes an ARE (algebraic Riccati equation)-based control technique applicable. Moreover, in the controller design, a Bryson scaling method is used to obtain desirable properties of the closed-loop system. The numerical techniques for solving ARE with the gradient damping factor are proposed and described. Results for applied control strategy are obtained by simulations and compared with measurement.

Findings
The proposed control technique can ensure optimal dynamic response, small steady-state error and energy saving. The effectiveness of the proposed control strategy is verified via numerical simulation and experiment.

Originality/value
The authors introduced an innovative approach to the well-known control methodology and settled their research in the newest literature coverage for this issue.
Computation of accurate solutions when using element-free Galerkin methods for solving structural problems
Authors: Joldes Grand Roman , Teakle Peter , Wittek Adam , Miller Karol 
Published: March 2017

Purpose
This paper aims to investigate the application of adaptive integration in element-free Galerkin methods for solving problems in structural and solid mechanics to obtain accurate reference solutions.

Design/methodology/approach
An adaptive quadrature algorithm which allows user control over integration accuracy, previously developed for integrating boundary value problems, is adapted to elasticity problems. The algorithm allows the development of a convergence study procedure that takes into account both integration and discretisation errors. The convergence procedure is demonstrated using an elasticity problem which has an analytical solution and is then applied to accurately solve a soft-tissue extension problem involving large deformations.

Findings
The developed convergence procedure, based on the presented adaptive integration scheme, allows the computation of accurate reference solutions for challenging problems which do not have an analytical or finite element solution.

Originality/value
This paper investigates the application of adaptive quadrature to solid mechanics problems in engineering analysis using the element-free Galerkin method to obtain accurate reference solutions. The proposed convergence procedure allows the user to independently examine and control the contribution of integration and discretisation errors to the overall solution error. This allows the computation of reference solutions for very challenging problems which do not have an analytical or even a finite element solution (such as very large deformation problems).
Numerical comparison of some contact detection algorithms
Authors: Schiava D'Albano Guillermo Gonzalo , Lukas Tomas , Su Fang , Korakianitis Theodosios , Munjiza Ante 
Published: March 2017

Purpose
Contact interaction and contact detection (CD) remain key components of any discontinua simulations. The methods of discontinua include combined finite-discrete element method (FDEM), discrete element method, molecular dynamics, etc. In recent years, a number of CD algorithms have been developed, such as Munjiza–Rougier (MR), Munjiza–Rougier–Schiava (MR-S), Munjiza-No Binary Search (NBS), Balanced Binary Tree Schiava (BBTS), 3D Discontinuous Deformation Analysis and many others. This work aims to conduct a numerical comparison of certain algorithms often used in FDEM for bodies of the same size. These include MR, MR-S, NBS and BBTS algorithms.

Design/methodology/approach
Computational simulations were used in this work.

Findings
In discrete element simulations where particles are introduced randomly or in which the relative position between particles is constantly changing, the MR and MR-S algorithms present an advantage in terms of CD times.

Originality/value
This paper presents a detailed comparison between CD algorithms. The comparisons are performed for problem cases with different lattices and distributions of particles in discrete element simulations. The comparison includes algorithms that have not been evaluated between them. Also, two new algorithms are presented in the paper, MR-S and BBTS.
Numerical solution of mixed convection in a lid-driven cavity with arc-shaped moving wall
Authors: Ismael Muneer A. 
Published: March 2017

Purpose
This paper investigates a numerical treatment to steady mixed convection in a lid-driven square cavity with arc-shaped moving wall or lid. The horizontal walls are thermally insulated. The vertical left wall is kept isothermally at high temperature, while the right arc-shaped moving wall is kept isothermally at low temperature.

Design/methodology/approach
Finite difference method in Cartesian coordinates with the upwind scheme is used in numerical solution. The irregular curved boundary has been treated by invoking non-uniform mesh grid with the ability to generate boundary fitted nodes. Jensen’s formulas of Neumann’s boundary condition have derived for the non-uniform mesh grid. The arc-shaped moving wall is considered as a segment of a rotating cylinder; thus, the studied pertinent parameters are the rotational speed of the arc-shaped wall in both aiding and opposing directions ω = −1,000-1,000, the arc-wall radius Ro = 0.5099-1.534 which is governed by its center (X0, Y0) = (1.1, 0.5)-(2.45, 0.5) and the Rayleigh number Ra = 103 − 106.

Findings
The results have shown that for low Rayleigh numbers, the rotational speed enhances heat transfer irrespective to the direction of rotation, while for high Rayleigh numbers, the aiding anticlockwise rotation (negative ω) enhances the heat transfer, while the opposing clockwise rotation (positive ω) manifests a retardation effect on the heat transfer. For a motionless arc-wall, its radius is ineffective for aiding heat transfer, while for non-zero arc-shaped wall speed, the heat transfer is an increasing function of its radius.

Originality/value
The arc-shaped moving wall has never been investigated until now. Therefore, the originality of this paper is due to studying the mixed convection in a lid-driven cavity with moving arc-shaped wall and inspecting the effect of its curvature and rotational speed in both directions on the flow and thermal fields.
Profiling causative factors leading to construction project delays in the United Arab Emirates
Authors: Mpofu Bekithemba , Ochieng Edward Godfrey , Moobela Cletus , Pretorius Adriaan 
Published: March 2017

Purpose
A voluminous amount of research has been conducted on project delay in the recent past; however, the persistence of the problem demands that a relentless quest for solutions is upheld. It can be argued that the problem is likely to be more pronounced in areas where development pressure is the highest. One such area is the United Arab Emirates (UAE) where the construction industry is said to have reached an unparalleled position in the last decade. The purpose of this paper is to identify the most significant causes of delays in the UAE construction industry.

Design/methodology/approach
A survey was conducted targeting three key types of stakeholders, namely clients, contractors and consultants. Validity and reliability were achieved by first assessing the plausibility of construction delay variables in UAE. The verification took place after the interpretation of quantitative data, this involved presenting the findings to the main participants. The validation took place after the verification process. Rigour was achieved by engaging participants previously engaged in UAE and focussing on verification and validation, this included responsiveness of the researchers during group discussions, methodological coherence, appropriate sampling frame and data analysis.

Findings
From the analysis, the study unveiled a number of important causes of construction delays in the UAE, ranging from unrealistic contract durations to poor labour productivity, with consultants and clients seemingly shouldering the bulk of the “blame game”. It was evident that all the three main stakeholders in a construction project (clients, consultants and contractors) need to change their existing practices in order to ensure timely delivery of projects. The research also confirms that delays are country specific and appear to be time related hence they should be viewed within the social, economic and cultural settings of the UAE.

Research limitations/implications
A major limitation of the current study was the use of a single approach to facilitate data collection.

Practical implications
It was evident that practitioners need to change their existing practices in order to ensure timely delivery of projects. Continuous coordination and relationship between practitioners are required through the project life cycle in order to solve problems and develop project performance.

Originality/value
As suggested in this study methods should be put in place to reduce long and bureaucratic processes within the client’s organisations, not only to fulfil the requirements of the contract but also to suite fast-track projects.
Implementing health promotion programs in the Australian construction industry
Authors: Loudoun Rebecca , Townsend Keith 
Published: March 2017

PurposeThe purpose of this paper is to identify possible agents and levers to trigger the development and implementation of work place health promotion programs (WHPPs) in the Australian construction industry. Unlike most large workplaces and most high-risk workplaces, these programs are rarely found in the construction sector.Design/methodology/approachQualitative interviews with 80 trades workers and site-based and off-site construction managers are used to reveal perceptions of the impact of WHPPs and ill-health and poor health behaviors on site activities with a view to identifying leverage points to introduce WHPPs in construction.FindingsUnhealthy lifestyle behaviors are seen as impacting on sites in three main ways: productivity (broadly defined), safety and interpersonal relations. Results also reveal specific roles and levers for different actors in the supply chain and a clear desire for a collective, industry-based response to identified health problems.Practical implicationsHigh levels of chronic diseases in the construction industry means firms within the sector must make a concerted attempt to change patterns of behavior or face significant long-term health implications for their workforce. Reducing levels of health and longevity of the workforce, mean work performance, productivity and participation is likely to decline.Originality/valueAlthough construction workers are recognized as one of the workforces at most risk for life limiting diseases such as Type 2 diabetes and cardiovascular disease, relatively little work has investigated health and well-being considerations for construction workers. This study contributes by investigating possible levers and agents to create healthier workplaces in construction.
Influence of initial trust on control from client perspective: construction industry in China
Authors: Jiang Weiping , Lu Yujie 
Published: March 2017

PurposeThe purpose of this paper is to investigate the effects of initial trust on control in the construction projects from the perspective of the client. The results are a good resource in managing the relationship between trust and control in the construction industry in China, and formulating a good working relationship with contractors.Design/methodology/approachUsing a set of questionnaire, data were collected from project managers of the clients, who are responsible for the overall project management and have face-to-face interaction with the contractors. The data were analyzed by structural equation modeling to identify the effects of initial trust on control for the contractors.FindingsTrust is examined in the construction industry in China through calculative and relational trust. Their effects are examined on three modes of inter-organizational control: outcome control, behavior control and social control. The results show that the calculative trust has strong effects on outcome-based and behavior control, while the relational trust, on social control.Research limitations/implicationsFirst, the conclusion of this research is based on the construction industry in China. It may not be suitable for other industries or other countries. Second, there may be other factors that influence the relationship between trust and control, such as the characteristics of the client and organizational culture, which are not taken into consideration in this research.Practical implicationsThe effects of initial trust on control have been testified in the study. For the client, it is wise to take suitable control measures to face with the contractors with the consideration of initial trust. The contractors would apply the rule in the relationship between initial trust and control, and set up good relationship with the client.Originality/valueThis research has certain originality and value in theory and practice. First, this research analyzes the relationship between trust and control in a dynamical way, which has innovative significance to some extent. Second, research on inter-organization supplies a new perspective about project control. Finally, this research would offer a perspective to improve the present situation of the construction industry in China. If the clients use the trust and control measures appropriately, the harmonious relation can be achieved and projects performance can be improved.
Ibrahim – the cassava starch processor
Authors: Ohu Eugene Agboifo 
Published: March 2017

Subject area
AgriBusiness entrepreneurship

Study level/applicability
Post-graduate and executive education classes in agribusiness: MBA, Executive Education programmes for senior managers; entrepreneurial studies and workshops for SMEs.

Case overview
This case study is centred on Ibrahim, a businessman in Tanzania, who decided to start a business to process and sell cassava starch flour. Following a market survey, he realized that the demand for cassava starch surpassed the supply and planned to bridge this gap. To realize his business idea, he applied for and received a loan from an investment bank (Tanzania Investment bank), with which he bought processing machines and some acres of land for the cultivation of the crop. Unfortunately, he encountered a major setback because the sub-standard processing machine he bought stopped working after one week. He could neither repair his equipment nor buy new ones because the bank refused to extend his loan facility. Ibrahim was also having problems meeting a huge international and local demand for his cassava because of inadequate supply of cassava by local farmers.

Expected learning outcomes
This paper aims to understand the entire cassava value chain, which is made up of three major players: growers, processors and end-users; to understand the business case for opting to focus on one of the three areas, what arguments could be given for being a grower, a processor or an end-user; to understand that there are different types of end-user products: cassava starch flour, high-quality cassava flour, both of which can come from an intermediate product called “grates”; to understand the reason for the paradox, that there is (potentially) a high demand for cassava flour locally, and yet these end-users are not yet willing to patronize the local market because supply is low, and supply is low, not because farmers cannot produce more, but simply because they are not processing more – why is this?; to understand that the “processing” stage seem to be the rate-limiting-stage in the cassava starch production value chain – how can this process be improved?; to understand the case for aggregating local farmers into cooperatives to produce enough cassava roots to feed the need of industrial processors, and aggregators can also collect and pre-process into “grates” before selling to industrial processing companies; and to understand the importance of locating processing plants close to the farms.

Supplementary materials
Teaching notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes.

Subject code
CSS 3: Entrepreneurship.
Effects of moving lid direction on mixed convection and entropy generation in a cubical cavity with longitudinal triangular fin insertion
Authors: Kolsi Lioua , Öztop Hakan F. , Abu-Hamdeh Nidal , Mohamad Naceur Borjini , Ben Assia Habib 
Published: March 2017

Purpose
The main purpose of this work is to arrive at a three-dimensional (3D) numerical solution on mixed convection in a cubic cavity with a longitudinally located triangular fin in different sides.

Design/methodology/approach
The 3D governing equations are solved via finite volume technique by writing a code in FORTRAN platform. The governing parameters are chosen as Richardson number, 0.01 ≤ Ri ≤ 10 and thermal conductivity ratio 0.01 ≤ Rc ≤ 100 for fixed parameters of Pr = 0.7 and Re = 100. Two cases are considered for a lid-driven wall from left to right (V+) and right to left (V−).

Findings
It is observed that entropy generation due to heat transfer becomes dominant onto entropy generation because of fluid friction. The most important parameter is the direction of the moving lid, and lower values are obtained when the lid moves from right to left.

Originality
The main originality of this work is to arrive at a solution of a 3D problem of mixed convection and entropy generation for lid-driven cavity with conductive triangular fin attachments.
Natural convection of nanofluid inside a wavy cavity with a non-uniform heating
Authors: Sheremet Mikhail , Pop Ioan , Öztop Hakan F. , Abu-Hamdeh Nidal 
Published: March 2017

Purpose
The main purpose of this numerical study is to study on entropy generation in natural convection of nanofluid in a wavy cavity using a single-phase nanofluid model.

Design/methodology/approach
The cavity is heated non-uniformly from the wavy wall and cooled from the right side while it is insulated from the horizontal walls. The physical domain of the problem is transformed into a rectangular geometry in the computational domain using an algebraic coordinate transformation by introducing new independent variables ξ and η. The governing dimensionless partial differential equations with corresponding initially and boundary conditions were numerically solved by the finite difference method of the second-order accuracy. The governing parameters are Rayleigh number (Ra = 1000-100000), Prandtl number (Pr = 6.82), solid volume fraction parameter of nanoparticles (φ = 0.0-0.05), aspect ratio parameter (A = 1), undulation number (κ = 1-3), wavy contraction ratio (b = 0.1-0.3) and dimensionless time (τ = 0-0.27).

Findings
It is found that the average Bejan number is an increasing function of nanoparticle volume fraction and a decreasing function of the Rayleigh number, undulation number and wavy contraction ratio. Also, an insertion of nanoparticles leads to an attenuation of convective flow and enhancement of heat transfer.

Originality
The originality of this work is to analyze the entropy generation in natural convection within a wavy nanofluid cavity using single-phase nanofluid model. The results would benefit scientists and engineers to become familiar with the flow behaviour of such nanofluids, and will be a way to predict the properties of this flow for the possibility of using nanofluids in advanced nuclear systems, in industrial sectors including transportation, power generation, chemical sectors, ventilation, air-conditioning, etc.
A simple analytical approach to a nonlinear equation arising in porous catalyst
Authors: He Chun-Hui 
Published: March 2017

Purpose
Analytical methods are widely used in heat and fluid flow; the purpose of this paper is to couple Taylor series method and Bubbfil algorithm to solve nonlinear differential equations.

Design/methodology/approach
A series solution is obtained with some unknown constants, which can be determined by incorporating boundary conditions, and the constants are calculated by the Bubbfil algorithm.

Findings
This paper gives an analytical approach to a nonlinear equation arising in porous catalyst using Taylor series and Bubbfil algorithm, and a high accuracy can be achieved.

Research limitations/implications
The coupled method of Taylor series and Bubbfil algorithm is a powerful method for nonlinear differential equations.

Practical implications
The proposed technology can be used in various numerical methods.

Originality/value
A new analytical method is proposed based on Taylor series and Bubbfil algorithm, which is a development of Newton’s iteration method and an ancient Chinese algorithm. The solution process is simple and easy to follow.