Search results

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Data envelopment analysis and accounting rates are implemented to do so.

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.

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).

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.

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.

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.

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.

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.

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.

The analysis presented here is the first to give concrete recommendations for the implementation of such infrastructure.

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.

This paper aims to provide a clarification of the meaning of the term integration.

A taxonomy of integration definitions derived from the academic and trade literature is developed, analyzed, and documented.

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.

The paper is not exhaustive, since new definitions of integration may exist or may emerge.

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.

The purpose of this paper is to analyze what transaction costs are acceptable for customers in different investments. In this study, two life insurance contracts, a mutual fund and a risk-free investment, as alternative investment forms are considered. The first two products under scrutiny are a life insurance investment with a point-to-point capital guarantee and a participating contract with an annual interest rate guarantee and participation in the insurer’s surplus. The policyholder assesses the various investment opportunities using different utility measures. For selected types of risk profiles, the utility position and the investor’s preference for the various investments are assessed. Based on this analysis, the authors study which cost levels can make all of the products equally rewarding for the investor.

The paper notes the risk-neutral valuation calibration using empirical data utility and performance measurement dynamics underlying: geometric Brownian motion numerical examples via Monte Carlo simulation.

In the first step, the financial performance of the various saving opportunities under different assumptions of the investor’s utility measurement is studied. In the second step, the authors calculate the level of transaction costs that are allowed in the various products to make all of the investment opportunities equally rewarding from the investor’s point of view. A comparison of these results with transaction costs that are common in the market shows that insurance companies must be careful with respect to the level of transaction costs that they pass on to their customers to provide attractive payoff distributions.

To the best of the authors’ knowledge, their research question – i.e. which transaction costs for life insurance products would be acceptable from the customer’s point of view – has not been studied in the above described context so far.

This paper discusses the factors that will influence a publisher's choice of cost‐effective electronic and media delivery techniques while allowing growth potential that serves the needs of end‐users. The paper describes the use of diskettes, Bernoulli removable cartridge disks, CD‐ROMs, modems using dial‐up phone lines, leased phone lines, satellites, and FM subcarriers. Sample data sizings evaluated include spreadsheet and word processing application programs, catalog distribution, CAD and accounting data files, online databases, news and financial information, and database updates. The economics of each delivery technique are given as well as the advantages and disadvantages.

The purpose of this paper is to attempt an aerospaceplane design with the objective of Low-Earth-Orbit-and-Return-to-Earth (LEOARTE) under the constraints of safety, low cost, reliability, low maintenance, aircraft-like operation and environmental compatibility. Along the same lines, a “sister” point-to-point flight on Earth Suborbital Aerospaceplane is proposed.

The LEOARTE aerospaceplane is based on a simple design, proven low risk technology, a small payload, an aerodynamic solution to re-entry heating, the high-speed phase of the outgoing flight taking place outside the atmosphere, a propulsion system comprising turbojet and rocket engines, an Air Collection and Enrichment System (ACES) and an appropriate mission profile.

It was found that a LEOARTE aerospaceplane design subject to the specified constraints with a cost as low as 950 United States Dollars (US$) per kilogram into Low Earth Orbit (LEO) might be feasible. As indicated by a case study, a LEOARTE aerospaceplane could lead, among other activities in space, to economically viable Space-Based Solar Power (SBSP). Its “sister” Suborbital aerospaceplane design could provide high-speed, point-to-point flights on the Earth.

The proposed LEOARTE aerospaceplane design renders space exploitation affordable and is much safer than ever before.

This paper provides an alternative approach to aerospaceplane design as a result of a new aerodynamically oriented Thermal Protection System (TPS) and a, perhaps, improved ACES. This approach might initiate widespread exploitation of space and offer a solution to the high-speed “air” transportation issue.