19,115 research outputs found
Towards a Formalism-Based Toolkit for Automotive Applications
The success of a number of projects has been shown to be significantly
improved by the use of a formalism. However, there remains an open issue: to
what extent can a development process based on a singular formal notation and
method succeed. The majority of approaches demonstrate a low level of
flexibility by attempting to use a single notation to express all of the
different aspects encountered in software development. Often, these approaches
leave a number of scalability issues open. We prefer a more eclectic approach.
In our experience, the use of a formalism-based toolkit with adequate notations
for each development phase is a viable solution. Following this principle, any
specific notation is used only where and when it is really suitable and not
necessarily over the entire software lifecycle. The approach explored in this
article is perhaps slowly emerging in practice - we hope to accelerate its
adoption. However, the major challenge is still finding the best way to
instantiate it for each specific application scenario. In this work, we
describe a development process and method for automotive applications which
consists of five phases. The process recognizes the need for having adequate
(and tailored) notations (Problem Frames, Requirements State Machine Language,
and Event-B) for each development phase as well as direct traceability between
the documents produced during each phase. This allows for a stepwise
verification/validation of the system under development. The ideas for the
formal development method have evolved over two significant case studies
carried out in the DEPLOY project
Automatic allocation of safety requirements to components of a software product line
Safety critical systems developed as part of a product line must still comply with safety standards. Standards use the concept of Safety Integrity Levels (SILs) to drive the assignment of system safety requirements to components of a system under design. However, for a Software Product Line (SPL), the safety requirements that need to be allocated to a component may vary in different products. Variation in design can indeed change the possible hazards incurred in each product, their causes, and can alter the safety requirements placed on individual components in different SPL products. Establishing common SILs for components of a large scale SPL by considering all possible usage scenarios, is desirable for economies of scale, but it also poses challenges to the safety engineering process. In this paper, we propose a method for automatic allocation of SILs to components of a product line. The approach is applied to a Hybrid Braking System SPL design
Power Flow Modelling of Dynamic Systems - Introduction to Modern Teaching Tools
As tools for dynamic system modelling both conventional methods such as
transfer function or state space representation and modern power flow based
methods are available. The latter methods do not depend on energy domain, are
able to preserve physical system structures, visualize power conversion or
coupling or split, identify power losses or storage, run on conventional
software and emphasize the relevance of energy as basic principle of known
physical domains. Nevertheless common control structures as well as analysis
and design tools may still be applied. Furthermore the generalization of power
flow methods as pseudo-power flow provides with a universal tool for any
dynamic modelling. The phenomenon of power flow constitutes an up to date
education methodology. Thus the paper summarizes fundamentals of selected power
flow oriented modelling methods, presents a Bond Graph block library for
teaching power oriented modelling as compact menu-driven freeware, introduces
selected examples and discusses special features.Comment: 12 pages, 9 figures, 4 table
An Aerodynamic Assessment of Vehicle-Side Wall Interaction using Numerical Simulation
The effects of induced pressure loads from a realistic vehicle onto the surface of a
road-side wall are numerically investigated. Parameters such as vehicle speeds, vehicle-wall
separation distances and the effects of inclined walls are examined to numerically characterise the
vehicle-wall interactions. Aerodynamic characteristics such as the drag, lift, side forces and
pressure co-efficients are analysed on the vehicle to provide a basis for comparison between each
of the aforementioned variations. Our results demonstrate that a smaller separation distance
between vehicle and wall enhances the pressure induced on both the wall and car which is found
to be consistent with the experimental data published previously. We find that the presence of a
wall in close proximity to the passing vehicle unfavourably influences the induced pressure on the
side-wall and abruptly increases the drag, lift and side forces experienced by the vehicle. For a
vertical side-wall, from a wall separation point of view, a separation distance of 1.35 normalised by
the height of the vehicle tends to retrieve the cars’ original drag and lift value. In addition, our results
demonstrate that a wall inclined to the ground favourably influences the aerodynamic
characteristics of the vehicle compared to its vertical counterpart
A Calculus for Orchestration of Web Services
Service-oriented computing, an emerging paradigm for distributed computing based on the use of services, is calling for the development of tools and techniques to build safe and trustworthy systems, and to analyse their behaviour. Therefore, many researchers have proposed to use process calculi, a cornerstone of current foundational research on specification and analysis of concurrent, reactive, and distributed systems. In this paper, we follow this approach and introduce CWS, a process calculus expressly designed for specifying and combining service-oriented applications, while modelling their dynamic behaviour. We show that CWS can model all the phases of the life cycle of service-oriented applications, such as publication, discovery, negotiation, orchestration, deployment, reconfiguration and execution. We illustrate the specification style that CWS supports by means of a large case study from the automotive domain and a number of more specific examples drawn from it
A decision support methodology to enhance the competitiveness of the Turkish automotive industry
This is the post-print (final draft post-refereeing) version of the article. Copyright @ 2013 Elsevier B.V. All rights reserved.Three levels of competitiveness affect the success of business enterprises in a globally competitive environment: the competitiveness of the company, the competitiveness of the industry in which the company operates and the competitiveness of the country where the business is located. This study analyses the competitiveness of the automotive industry in association with the national competitiveness perspective using a methodology based on Bayesian Causal Networks. First, we structure the competitiveness problem of the automotive industry through a synthesis of expert knowledge in the light of the World Economic Forum’s competitiveness indicators. Second, we model the relationships among the variables identified in the problem structuring stage and analyse these relationships using a Bayesian Causal Network. Third, we develop policy suggestions under various scenarios to enhance the national competitive advantages of the automotive industry. We present an analysis of the Turkish automotive industry as a case study. It is possible to generalise the policy suggestions developed for the case of Turkish automotive industry to the automotive industries in other developing countries where country and industry competitiveness levels are similar to those of Turkey
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