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1 – 10 of over 2000Igor Vušanović and Vaughan R Voller
When a multi component alloy solidifies the redistribution of solute components leads to the formation of macrosegregation patterns. Blending ideas from a number of recent…
Abstract
Purpose
When a multi component alloy solidifies the redistribution of solute components leads to the formation of macrosegregation patterns. Blending ideas from a number of recent publications the purpose of this paper is to provide a “best practice” on how grid convergence of a given macrosegregation simulation can be measured and determined.
Design/methodology/approach
The best practice is arrived at by considering a benchmark problem consisting of a 2D-casting simulation of an idealized Al-4.5%Cu alloy in a side cooled square (76×76 mm) cavity. The model for this simulation is based on a mixture treatment of the relevant heat and mass transfer equations. Simulations are made using three increasingly refined grid sizes.
Findings
The best practice to determine grid resolution involves two steps: first, a visual evaluation of predicted segregation images leading to the evaluation of solute profiles along selected transects; and second, the construction of a cumulative distribution function (CDF) of the predicted segregation field. On application to the benchmark problem, it is concluded that current computer resources are insufficient to grid resolve macrosegregation patterns but that the CDF provides a useful signal of the nature of macrosegregation in a given system.
Research limitations/implications
The benchmark is chosen to be representative. Exact convergence behavior, however, may depend on the system chosen.
Originality/value
In addition to establishing a best practice for measuring grid resolution of macrosegregation simulations the work also highlights, even in the absence of complete grid convergence, how the recently proposed CDF treatment can inform solidification modeling and process understanding.
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Mohamed Rady, Eric Arquis, Dominique Gobin and Benoît Goyeau
This paper aims to tackle the problem of thermo‐solutal convection and macrosegregation during ingot solidification of metal alloys. Complex flow structures associated with the…
Abstract
Purpose
This paper aims to tackle the problem of thermo‐solutal convection and macrosegregation during ingot solidification of metal alloys. Complex flow structures associated with the development of channels segregate and sharp gradients in the solutal field call for the implementation of accurate methods for numerical modeling of alloy solidification. In particular, the solute transport equation is convection dominated and requires special non‐oscillarity type high‐order schemes to handle the regions of channels segregates.
Design/methodology/approach
In the present study, a time‐splitting approach has been adopted to separately handle solute advection and diffusion. This splitting technique allows the application of accurate total variation dimensioning (TVD) schemes for solution of solute advection. Applications of second‐order Lax‐Wendroff TVD SUPERBEE and fifth‐order weighted essentially non‐oscillatory (WENO) schemes are described in the present article. Classical numerical solution of solute transport using hybrid and central‐difference schemes are also employed for the purpose of comparisons. Numerical simulations for solidification of Pb‐18%Sn in a two‐dimensional rectangular cavity have been carried out using different numerical schemes.
Findings
Numerical results show the difficulty of obtaining grid‐independent solutions with respect to local details in the region of channels. Grid convergence patterns and numerical uncertainty are found to be dependent on the applied scheme. In general, the first‐order hybrid scheme is diffusive and under predicts the formation of channels. The second‐order central‐difference scheme brings about oscillations with possible non‐physical extremes of solute composition in the region of channel segregates due to sharp gradients in the solutal field. The results obtained using TVD and WENO schemes contain no oscillations and show an excellent capture of channels formation and resolution of the interface between solute‐rich and depleted bands. Different stages of channels formation are followed by analyzing thermo‐solutal convection and macrosegregation at different times during solidification.
Research limitations/implications
Accurate prediction of local variation in the solutal and flow fields in the channels regions requires grid refinement up to scales in the order of microscopic dendrite arm spacing. This imposes limitations in terms of large computational time and applicability of available macroscopic models based on classical volume‐averaging techniques.
Practical implications
The present study is very useful for numerical simulation of macrosegregation during ingot casting of metal alloys.
Originality/value
The paper provides the methodology and application of TVD schemes to predict channel segregates during columnar solidification of metal alloys. It also demonstrates the limitations of classical schemes for simulation of alloy solidification.
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The purpose of this paper is to simulate two macrosegregation benchmarks with a newly developed stabilized finite element algorithm based on a semi-implicit pressure correction…
Abstract
Purpose
The purpose of this paper is to simulate two macrosegregation benchmarks with a newly developed stabilized finite element algorithm based on a semi-implicit pressure correction scheme.
Design/methodology/approach
A streamline-upwind/Petrov–Galerkin (SUPG) stabilized finite element algorithm is developed for the coupled conservation equations of mass, momentum, energy and species. A semi-implicit pressure correction method combined with SUPG stabilization technique is proposed to solve the convection flow during solidification. An analytically derived enthalpy method is adopted to solve the energy conservation equation. The nonlinearities of the energy and species equations are tackled by Newton–Raphson method. Two macrosegregation benchmarks considering the solidification of an Al-4.5 per cent Cu alloy and a Sn-10 per cent Pb alloy are simulated.
Findings
A very good agreement is achieved by comparison with the classical finite volume method and a novel meshless method for the Al-4.5 per cent Cu alloy solidification benchmark. Moreover, a unique reference numerical solution has been obtained. Besides, it is demonstrated that the stabilized finite element algorithm can capture the flow instability and channel segregation during solidification of the Sn-10 per cent Pb alloy.
Originality/value
A semi-implicit pressure correction method combined with SUPG stabilization technique is adopted to develop robust stabilized finite element algorithm for the macrosegregation model. A new enthalpy formulation for heat transfer problems with phase change is derived analytically.
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Jorge Luiz Gayotto de Borba, Mauricio Rodrigues de Magalhães, Raquel Stefan Filgueiras and Marina Bouzon
Performing retailing in a complete omnichannel manner is not a simple task, and it considerably increases the complexity of supply chain management operations. This paper aimed at…
Abstract
Purpose
Performing retailing in a complete omnichannel manner is not a simple task, and it considerably increases the complexity of supply chain management operations. This paper aimed at identifying the barriers hindering efficient management of a return channel in this type of retail.
Design/methodology/approach
A systematic literature review procedure was used, including descriptive and content analysis of results. The review was performed using four academic databases. Applicable barriers were categorized thematically, a conceptual framework was proposed and future research avenues were drawn.
Findings
The contribution of this paper comprises a theoretical description of reverse logistics applied to omnichannel retail, the identification of the return barriers in omnichannel and a conceptual framework for a holistic view of the problem. In all, 43 barriers were identified including high investments, product restocking, additional transportation costs and poor communication.
Research limitations/implications
The link between reverse logistics and omnichannel area is recent and publications are still scarce, so the newness of this study limits the opportunity for further deepening or more robust validation of the results.
Practical implications
The results offered may be used by managers in the areas of retail and supply chain management in general in order to reduce the natural complexity in omnichannel environment.
Originality/value
Regarding previous literature on omnichannel retail, only a few works consider the after-sales stage. This work intended to pave the way in this poorly explored intersection (reverse logistics and omnichannel) by presenting a conceptual framework to classify various barriers in omnichannel retail return.
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Heiko Tillwick and Martin S. Olivier
This paper aims to propose an anonymous web‐browsing protocol that harnesses some of the advantages of store‐and‐forward anonymity solutions whilst retaining some of the…
Abstract
Purpose
This paper aims to propose an anonymous web‐browsing protocol that harnesses some of the advantages of store‐and‐forward anonymity solutions whilst retaining some of the interactive properties of web browsing. Anonymity research on high latency, store‐and‐forward mediums such as e‐mail have led to comparatively well‐researched anonymity technologies. However, similar achievements have proven to be more difficult for low‐latency communications such as web browsing.
Design/methodology/approach
A review of existing anonymity solutions notes the advantages of mix technologies versus the advantages offered by Onion Routing. A solution is presented that features a combined approach of both solutions.
Findings
The proposed protocol differentiates between web requests and web responses – a request is treated as a store‐and‐forward message whilst the response is handled as a data stream.
Originality/value
The solution described can be used by existing anonymous web browsing solutions in order to improve the level of anonymity whilst minimising the overhead of anonymously distributing web content.
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Alexander Hübner, Johannes Wollenburg and Andreas Holzapfel
Online retailing changes all retail systems significantly. The growing importance of online sales requires the creation of new fulfillment models. The purpose of this paper is to…
Abstract
Purpose
Online retailing changes all retail systems significantly. The growing importance of online sales requires the creation of new fulfillment models. The purpose of this paper is to investigate how retailers develop from separate multi-channel (MC) to integrated omni-channel (OC) fulfillment. OC retailing has an integrated perspective, with seamless interactions between online and bricks-and-mortar channels.
Design/methodology/approach
More than 60 internationally active retailers and experts from Germany participated in an exploratory survey. With a response rate of 40 percent the authors achieved the goal to adequately depict the German MC and OC retail market. It is currently the largest empirical study of MC and OC fulfillment.
Findings
It is the first study to comprehensively analyze the logistical development options open to retailers for integrated fulfillment. The authors discuss the conceptual development options and formulate propositions for an advanced OC fulfillment approach. OC retailers aim to pool their organizational units for fulfillment via different channels. Retailers with multiple channels develop their warehouse systems toward channel-integrated inventory enabling flexible and demand-driven inventory allocation. Retailers with channel-integrated inventory also organize their picking procedures in one common zone. The higher the outlet density, the more it becomes beneficial for retailers to introduce pick-up services.
Research limitations/implications
The research is based on insights from retailers and experts from companies based in Germany.
Practical implications
The findings provide an insight into designing OC fulfillment and distribution structures. The concepts themselves, archetypes, challenges and development paths are analyzed. Identified logistics levers can be adjusted to pinpoint the steps required to advance integration.
Originality/value
The authors contribute by deriving propositions and a framework for transitioning from basic MC to integrated, extended OC logistics. Because this research area is still comparatively young, the authors take a more comprehensive, exploratory view of OC fulfillment.
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The role of supply chain members is often relegated to an ancillary role in brand building. Do distributors serve only as a conduit for movement of products confined to the…
Abstract
The role of supply chain members is often relegated to an ancillary role in brand building. Do distributors serve only as a conduit for movement of products confined to the business-to-business (B2B) market or do they possess the capability to transcend boundaries and help build the brand of the products that they distribute? Using a case study methodology, an exploration has been carried out on the success journey of Al Seer Group, one of the biggest and oldest Fast Moving Consumer Goods distributors in the United Arab Emirates, driven by the vision to be a brand-building partner. The organization is propelled by a robust people strategy, a process-based operational framework, a data-driven culture and a strategic reorientation that helped them to introduce the brand-building perspective to their stakeholders. This study encourages further research interest on employee retention strategies focused on the Millennial and Gen Z workforce, challenges of data-driven organizations in implementation of emerging technologies, the role of C-suite executives in organizational strategic orientation, and the brand-building perspective of B2B distributors.
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Yenal Yagmur, Rüya Ehtiyar and Akin Aksu
The growing competition between the developing halal market and the countries in halal market has enhanced the interest of researchers in this field in recent years. In this…
Abstract
Purpose
The growing competition between the developing halal market and the countries in halal market has enhanced the interest of researchers in this field in recent years. In this context, this study aims to examine the studies published in the international literature on halal tourism between 1975 and 2019 in terms of bibliometric characteristics and to reveal tendencies and trends of these publications within the framework of certain parameters.
Design/methodology/approach
In accordance with this purpose, the topic of “halal tourism” was searched in the database of “Web of Science Core Collection,” and bibliometrics data in regard to the publications were reached. Publications on halal tourism were examined in the context of years, numbers, genres, research fields, fields of study, journals in which they are found, the number of authors and page number of publications, research approaches of publications, themes of publications, country where the research data was collected (examined), names of the authors in the publications and publication numbers of the authors, and the number of citations.
Findings
In this paper, it was determined that the studies in the field of halal tourism increased in recent years. It was concluded that these studies were mainly carried out after 2011 and showed a large increase in 2016, the majority of the publications were in the form of study-paper and the average number of citations in the field was 3.1, and h-index number was seven.
Research limitations/implications
This paper is based on bibliometric analysis. Bibliometric analyses were performed on the “Web of Science Core Collection.” Because of database searches were made only on “Web of Science Core Collection,” the publications that were not scanned here could not be analyzed.
Originality/value
This paper examined the studies on halal tourism between 1975 and 2019 with a bibliometric analysis technique. Thus, it is aimed to learn more about halal tourism and to provide the researchers who work in this field with information about the structure of this field.
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The basement and the first 11 floors, including the superb banking hall, were handed over in July and became fully operational at the beginning of August. The upper sections of…
Abstract
The basement and the first 11 floors, including the superb banking hall, were handed over in July and became fully operational at the beginning of August. The upper sections of the building are being progressively handed over; the whole building will be completed by November. Architects Foster Associates have worked with their client, the Hongkong and Shanghai Banking Corporation, to produce far more than a serviced shell; the building incorporates a host of sophisticated systems related to the various operational functions of the bank and has been termed a ‘finance factory’.
Mohamed Battour, Khalid Mady, Mohamed Salaheldeen, Mohamed Elsotouhy, Israa Elbendary and Erhan Boğan
This paper aims to present a theoretical account of the connection between artificial intelligence (AI) enabled technologies and Muslim-friendly tourism experiences (MFTX) using…
Abstract
Purpose
This paper aims to present a theoretical account of the connection between artificial intelligence (AI) enabled technologies and Muslim-friendly tourism experiences (MFTX) using the customer experience (CX) theory, reference group theory and theory of tourism consumption systems.
Design/methodology/approach
A model research design is adopted to build a theoretical framework that predicts relationships between constructs. Critical assessment in tourism and AI literature is used to explore AI-enabled technologies in Halal-friendly tourism.
Findings
The findings of this paper have conceptualised the CX theory for Muslim travellers satisfying their religious needs in Halal-friendly tourism by suggesting a new construct called the MFTX. It also offered a theoretical model for using AI-enabled technologies to improve the MFTX.
Originality/value
This study provides a new theoretical model for using AI-enabled technologies to improve the MFTX. This paper is also expected to provide suggestions for tourism operators and service providers to cater to Muslim tourists’ needs using AI technologies.
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