89,221 research outputs found
Realising the open virtual commissioning of modular automation systems
To address the challenges in the automotive industry posed by the need to rapidly manufacture more
product variants, and the resultant need for more adaptable production systems, radical changes are
now required in the way in which such systems are developed and implemented. In this context, two
enabling approaches for achieving more agile manufacturing, namely modular automation systems
and virtual commissioning, are briefly reviewed in this contribution. Ongoing research conducted at
Loughborough University which aims to provide a modular approach to automation systems design
coupled with a virtual engineering toolset for the (re)configuration of such manufacturing
automation systems is reported. The problems faced in the virtual commissioning of modular
automation systems are outlined. AutomationML - an emerging neutral data format which has
potential to address integration problems is discussed. The paper proposes and illustrates a
collaborative framework in which AutomationML is adopted for the data exchange and data
representation of related models to enable efficient open virtual prototype construction and virtual
commissioning of modular automation systems. A case study is provided to show how to create the
data model based on AutomationML for describing a modular automation system
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Modular assembly with postponement to improve health, safety & productivity in construction
This paper presents the outcome of an engineering study as part of the design and development of a lean and agile construction system and in particular its supply chain component. This combines modular assembly with a postponement function to be tested on a case study project (not reported here), the objective of which is to improve health, safety and productivity for the company sponsoring the research.
The contribution to research is the combination of countermeasures described in this paper that have been developed and incorporated into a wider construction system, in the same way that manufacturing has used this strategy with great success. Also, a further output is the development and use of an innovative method for assembling, transporting and installing mechanical and electrical modules, whereby modularization can be achieved with or without offsite manufacturing capability. The research forecasts a reduction of onsite labor of 35% compared to using traditional methods of construction, with less onsite operatives at risk of injury carrying out simpler assembly tasks within ergonomic mobile work cells. Further research is proposed to measure the benefits of the construction system following its implementation on a case study project
Modelling and Stability Analysis of Wind Power Plants Connected to Weak Grids
It is important to develop modelling tools to predict unstable situations resulting from the interactions between the wind power plant and the weak power system. This paper presents a unified methodology to model and analyse a wind power plant connected to weak grids in the frequency-domain by considering the dynamics of the phase lock loop (PLL) and controller delays, which have been neglected in most of the previous research into modelling of wind power plants to simplify modelling. The presented approach combines both dq and positive/negative sequence domain modelling, where a single wind turbine is modelled in the dq domain but the whole wind power plant connected to the weak grid is analysed in the positive/negative sequence domain. As the proposed modelling of the wind power plant is systematic and modular and based on the decoupled positive/negative sequence impedances, the application of the proposed methodology is relevant for transmission system operators (TSOs) to assess stability easily with a very low compactional burden. In addition, as the analytical dq impedance models of the single wind turbine are provided, the proposed methodology is an optimization design tool permitting wind turbine manufacturers to tune their converter control. As a case study, a 108 MW wind power plant connected to a weak grid was used to study its sensitivity to variations in network short-circuit level, X/R ratio and line series capacitor compensation (Xc/Xg)
On Conditional Decomposability
The requirement of a language to be conditionally decomposable is imposed on
a specification language in the coordination supervisory control framework of
discrete-event systems. In this paper, we present a polynomial-time algorithm
for the verification whether a language is conditionally decomposable with
respect to given alphabets. Moreover, we also present a polynomial-time
algorithm to extend the common alphabet so that the language becomes
conditionally decomposable. A relationship of conditional decomposability to
nonblockingness of modular discrete-event systems is also discussed in this
paper in the general settings. It is shown that conditional decomposability is
a weaker condition than nonblockingness.Comment: A few minor correction
Supervisory Control Synthesis of Discrete-Event Systems using Coordination Scheme
Supervisory control of discrete-event systems with a global safety
specification and with only local supervisors is a difficult problem. For
global specifications the equivalent conditions for local control synthesis to
equal global control synthesis may not be met. This paper formulates and solves
a control synthesis problem for a generator with a global specification and
with a combination of a coordinator and local controllers. Conditional
controllability is proven to be an equivalent condition for the existence of
such a coordinated controller. A procedure to compute the least restrictive
solution is also provided in this paper and conditions are stated under which
the result of our procedure coincides with the supremal controllable
sublanguage.Comment: 29 pages, 11 figure
Making Design Rules: A Multi-Domain Perspective
This study analyzes the processes whereby organizations develop radical innovations in response to environmental transformations. It explores the changes in organizational structures, practices and business strategies entailed by the implementation of such innovations. From the literature on modularity, we borrow the idea that the evolutionary dynamics of artifacts and organizations are linked by design rules, i.e. a set of principles that allocate functions to components, identify the operating principle of each component and determine the interfaces among modules. Through an in-depth case study of radical innovation in tire manufacturing, we study the joint dynamics of technical and organizational change during the transition from old to new design rules. We argue that technical change and organization adaptation are linked, but that such relationship is mediated and rendered open-ended by the evolution of the underlying bodies of knowledge.organizational change, innovation, technological change, modularity, tire manufacturing
Modular control-loop detection
This paper presents an efficient algorithm to
detect control-loops in large finite-state systems. The proposed
algorithm exploits the modular structure present in many
models of practical relevance, and often successfully avoids the
explicit synchronous composition of subsystems and thereby
the state explosion problem. Experimental results show that
the method can be used to verify industrial applications of
considerable complexity
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