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1 – 10 of over 1000Andreas Knorr, Andreas Lueg-Arndt and Alexander Eisenkopf
In their respective market outlooks, both Boeing and Airbus forecast strong growth in intercontinental passenger traffic until 2029. However, they differ substantially with…
Abstract
In their respective market outlooks, both Boeing and Airbus forecast strong growth in intercontinental passenger traffic until 2029. However, they differ substantially with respect to their assessment of the future development of airline (and alliance) networks. These deviating projections have, in turn, massively influenced their product range. Boeing, having long predicted a major growth in intercontinental point-to-point operations – based on the so-called fragmentation (dehubbing) hypothesis – has consistently opted for the development of the B787 (Dreamliner) family of midsized, and extremely efficient, wide-body aircraft. Airbus, on the contrary, is forecasting a substantial increasing demand for hub-to-hub traffic, which according to the company, will require airlines to purchase a large number of very large aircraft (VLA), especially its Airbus 380. Though both manufacturers did not put all their money where their mouths are – Boeing has reacted to the Airbus 380 challenge with an updated derivative of its Boeing 747 flagship, the Boeing 747-8 Intercontinental, while Airbus is targeting its proposed Airbus 350 family against both the Boeing 787 and Boeing 777 – the fragmentation hypothesis remains one of the most controversial issues in the civil aviation community today. Regardless of which scenario will eventually turn out to be more realistic, either will impact tremendously on aircraft manufacturers, on the airlines' route and fleet planning decisions as well as airport operators.
Binghai Zhou, Xiujuan Li and Yuxian Zhang
This paper aims to investigate the part feeding scheduling problem with electric vehicles (EVs) for automotive assembly lines. A point-to-point part feeding model has been…
Abstract
Purpose
This paper aims to investigate the part feeding scheduling problem with electric vehicles (EVs) for automotive assembly lines. A point-to-point part feeding model has been formulated to minimize the number of EVs and the maximum handling time by specifying the EVs and sequence of all the delivery tasks.
Design/methodology/approach
First, a mathematical programming model of point-to-point part feeding scheduling problem (PTPPFSP) with EVs is presented. Because the PTPPFSP is NP-hard, an improved multi-objective cuckoo search (IMCS) algorithm is developed with novel search strategies, possessing the self-adaptive Levy flights, the Gaussian mutation and elite selection strategy to strengthen the algorithm’s optimization performance. In addition, two local search operators are designed for deep optimization. The effectiveness of the IMCS algorithm is verified by dealing with the PTPPFSP in different problem scales.
Findings
Numerical experiments are used to demonstrate how the IMCS algorithm serves as an efficient method to solve the PTPPFSP with EVs. The effectiveness and feasibility of the IMCS algorithm are validated by approximate Pareto fronts obtained from the instances of different problem scales. The computational results show that the IMCS algorithm can achieve better performance than the other high-performing algorithms in terms of solution quality, convergence and diversity.
Research limitations/implications
This study is applicable without regard to the breakdown of EVs. The current research contributes to the scheduling of in-plant logistics for automotive assembly lines, and it could be modified to cope with similar part feeding scheduling problems characterized by just-in-time (JIT) delivery.
Originality/value
Both limited electricity capacity and no earliness and tardiness constraints are considered, and the scheduling problem is solved satisfactorily and innovatively for an efficient JIT part feeding with EVs applied to in-plant logistics.
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J.P.M. Gonçalves, M.F.S.F. de Moura, P.M.S.T. de Castro and A.T. Marques
An interface finite element for three‐dimensional problems based on the penalty method is presented. The proposed element can model joints/interfaces between solid finite elements…
Abstract
An interface finite element for three‐dimensional problems based on the penalty method is presented. The proposed element can model joints/interfaces between solid finite elements and also includes the propagation of damage in pure mode I, pure mode II and mixed mode considering a softening relationship between the stresses and relative displacements. Two different contact conditions are considered: point‐to‐point constraint for closed points (not satisfying the failure criterion) and point‐to‐surface constraint for opened points. The performance of the element is tested under mode I, mode II and mixed mode loading conditions.
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Lin Dong, Florian Richer, Agnes Roby-Brami and Guillaume Morel
When a robot comanipulates an object with a human user, damping is a useful function. This is achieved by programming the robot to exhibit a viscous field. For some specific…
Abstract
Purpose
When a robot comanipulates an object with a human user, damping is a useful function. This is achieved by programming the robot to exhibit a viscous field. For some specific applications, the viscosity is required to change according to the manipulation velocity. A reported method is programming the viscosity varying inversely to the velocity. In this paper, this method is experimentally shown to distort human’s natural motion performance. This paper aims to propose a solution to solve this instability problem.
Design/methodology/approach
The authors performed a point-to-point targeting movement, where it was observed that the instability results from a sudden reduction of robot’s resistance to motion, which further results from the abrupt viscosity drop when the subject tries to accelerate. Therefore, the authors propose a solution where a first-order linear filter is added to the viscosity coefficient so as to slow down its variation.
Findings
The experimental results confirm that the proposition is effective, with the ability to stabilize the comanipulated dynamics and to restore the human’s natural behavior.
Originality/value
This paper concerns applications of comanipulation where the viscosity coefficient is designed to decrease as the velocity increases. An instability problem, which was of vital importance in terms of safety and performance but unreported in the literature, was experimentally studied through human–robot experiments. A solution was proposed by including a secondary dynamics in the variations of the viscosity. Its effectiveness was supported by the practical point-to-point motion experiments.
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Luisa Marti, Rosa Puertas and Consuelo Calafat
The purpose of this paper is to study the efficiency and financial situation of Spanish airlines by conducting a comparative analysis of those operating in hubs and those that…
Abstract
Purpose
The purpose of this paper is to study the efficiency and financial situation of Spanish airlines by conducting a comparative analysis of those operating in hubs and those that employ the point-to-point system.
Design/methodology/approach
Data envelopment analysis and accounting rates are implemented to do so.
Findings
The results show that hubs do not result in the companies that use them being efficient. Instead, it is the charter, low-cost and private flight operators that best manage their resources.
Originality/value
The study makes a novel contribution to the literature, as there has been no research on Spanish airlines that compares the two types of operators (hubs and point to point).
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Franz Trieb, Juergen Kern, Natàlia Caldés, Cristina de la Rua, Dorian Frieden and Andreas Tuerk
The purpose of this paper is to shed light to the concept of solar electricity transfer from North Africa to Europe in the frame of Article 9 of the European Renewable Energy…
Abstract
Purpose
The purpose of this paper is to shed light to the concept of solar electricity transfer from North Africa to Europe in the frame of Article 9 of the European Renewable Energy Sources (EU-RES) Directive 28/2009/EC, to explain why efforts have not been successful up to now and to provide recommendations on how to proceed.
Design/methodology/approach
The authors have compared the “Supergrid” concept that was pursued by some institutions in the past years with the original “TRANS-CSP” concept developed by the German Aerospace Centre in 2006. From this analysis, the authors could identify not only major barriers but also possible ways towards successful implementation.
Findings
The authors found that in contrast to the Supergrid approach, the original concept of exporting dispatchable solar power from concentrating solar thermal power stations with thermal energy storage (CSP-TES) via point-to-point high voltage direct current (HVDC) transmission directly to European centres of demand could be a resilient business case for Europe–North Africa cooperation, as it provides added value in both regions.
Research limitations/implications
The analysis has been made in the frame of the BETTER project commissioned by the Executive Agency for Competitiveness & Innovation in the frame of the program Intelligent Energy Europe.
Practical implications
One of the major implications found is that due to the time lost in the past years by following a distracted concept, the option of flexible solar power imports from North Africa to Europe is not any more feasible to become part of the 2020 supply scheme.
Social implications
To make them a viable option for post-2020 renewable energy systems for electricity development in Europe, a key recommendation of the project is to elaborate a detailed feasibility study about concrete CSP-HVDC links urgently.
Originality/value
The analysis presented here is the first to give concrete recommendations for the implementation of such infrastructure.
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The upper three OSI layers support the communication requirements of applications, while the lower four layers provide reliable transmission of data. This article describes the…
Abstract
The upper three OSI layers support the communication requirements of applications, while the lower four layers provide reliable transmission of data. This article describes the lower four layers. First, though, a brief overview of the layered model is presented including a summary of the upper three layers. Then a description of the lower three layers is followed by a discussion of data communication standards associated with specific layers. Architectural concepts are then explored: hierarchy and abstraction within the layers, levels of dialogue, internetworking, end‐to‐end communication, analysis of layer four, and a discussion of connection‐oriented, connectionless, and message‐oriented protocols and applications. The article concludes with a comparison of OSI and the de facto industry protocols, TCP/IP, which are currently used within the Internet.
In this article, I propose a theory of network opportunity emergence. The core of the argument is that as an overall industry network structure becomes centralized, opportunities…
Abstract
In this article, I propose a theory of network opportunity emergence. The core of the argument is that as an overall industry network structure becomes centralized, opportunities emerge for new entrants. As the institutional environment evolves toward a centralized network flow structure, innovators can identify newly emerged rich resource niches that serve as the perfect breeding ground for an entrepreneurial start-up. While the framework is an aggregate level conceptualization of market opportunities, it also identifies specific actionable opportunities at a very micro level. Examples from the networks of the airline industry illustrate the logic. I conclude by discussing the innovation and entrepreneurship implications for a wide variety of industries and network tie types, calling for utilization of the framework to answer a broad variety of research questions.
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Richard Klophaus and Frank Fichert
There is a strong academic and professional interest in the changing business model of LCCs in Europe. Recently, even Ryanair which is often considered a European LCC role model…
Abstract
There is a strong academic and professional interest in the changing business model of LCCs in Europe. Recently, even Ryanair which is often considered a European LCC role model has departed from the point-to-point paradigm by offering transfers within its own network. We first provide a general overview of recent changes in the business model of airlines that used to be categorized as LCCs. We then add to existing studies on LCC network strategies toward building connections. While we distinguish different approaches to accommodate transfer passengers, our analysis focuses on mesh networks as an airline network topology other than hub-and-spoke networks to provide online connections. A schedule analysis of Ryanair’s direct and indirect services at its base at Porto airport exemplifies that a mesh network might allow LCCs to go beyond stand-alone operations to become network carriers without requiring a complete transition of the generic LCC business strategy.
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This paper aims to provide a clarification of the meaning of the term integration.
Abstract
Purpose
This paper aims to provide a clarification of the meaning of the term integration.
Design/methodology/approach
A taxonomy of integration definitions derived from the academic and trade literature is developed, analyzed, and documented.
Findings
Integration is a word that is commonly used when discussing enterprise applications. The term integration is inserted in technical papers, e‐mail messages, correspondence, proposals, and even causal conversations. After many years of project work, and many misunderstandings and failed meetings and workshops, it can only be stated that the word has multiple and misunderstood meanings. For technical papers (research and trade), the term must be provided with context, or it is impossible to have a meaningful conversation. Next, multiple alternative definitions (that are valid in the literature for the appropriate context) are presented and explained in some detail.
Research limitations/implications
The paper is not exhaustive, since new definitions of integration may exist or may emerge.
Originality/value
The main contribution of the paper is that it yields clarity on a key term that is frequently used in information systems research. The paper is useful to any researchers or practitioners who are focused on enterprise system implementation.
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