Coordination Specification for Distributed Optimal System Design Using the Chi Language

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76202/1/AIAA-2002-5410-847.pd

Coordination Specification of the Analytical Target Cascading Process using the Chi Language

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76587/1/AIAA-2002-5637-610.pd

How healthcare providers’ own death anxiety influences their communication with patients in end-of-life care: A thematic analysis

Healthcare providers’ own death anxiety can influence end-of-life communication. We interviewed nine palliative care health providers about their experiences of providing end-of-life care. Participants also completed the Revised Death Anxiety Scale. A thematic analysis of the interview transcripts identified one theme labelled ‘avoidant coping’ and another labelled ‘death anxiety awareness’, which are presented in the context of the participants’ own Revised Death Anxiety Scale scores. The findings show that avoidant death anxiety coping can compromise end-of-life communication, but that greater awareness of death anxiety can help overcome avoidant coping. The findings can inform potential improvements in healthcare practice and training.N/

Multi-level function specification and architecture analysis using ESL: a lock renovation pilot study

In this paper, we present a pilot study to show the first proof-of-principle of the recently developed Elephant Specification Language (ESL). The Prinses Marijke locks in the Netherlands are due for a major renovation. To effectively organize the renovation project, engineers need insight into the network of dependencies between components that are due for renewal and components that remain, to ensure that the replacement parts will fit and function properly in the existing structure. ESL is used to write a structured multi-level function specification for the Prinses Marijke locks. From this specification, multi-domain matrix (MDM) models of the system architecture are automatically derived at multiple levels of granularity. These models show dependencies between components, between functions, and combinations thereof. The MDM models are used to gain insight in the system architecture, to visualize which parts of the lock system are affected by the renovation, and to determine which dependencies have to be accounted for during the renovation process. This information is required to effectively organize the renovation project

Incomplete series expansion for function approximation

We present an incomplete series expansion (ISE) as a basis for function approximation. The ISE is expressed in terms of an approximate Hessian matrix which may contain second, third and even higher order ‘main ’ or diagonal terms, but which excludes ‘interaction ’ or off-diagonal terms. From the ISE, a family of approximate interpolating functions may be derived. The interpolating functions may be based on an arbitrary number of previously sampled points, and any of the function and gradient values at previously sampled points may be enforced when deriving the approximate interpolating functions. When function values only are enforced, the approximations are spherical, and the storage requirements are minimal. Irrespective of the conditions enforced, the approximate Hessian matrix is a sparse diagonal matrix. Hence the proposed interpolating functions are very well suited for use in sequential approximate optimization (SAO), based on computationally expensive simulations. In turn, computationally expensive simulations are often required in, for example, optimal structural design problems. We derive a selection of approximations from the family of ISE approximating functions herein; these include approximations based on the substitution of (reciprocal) intervening variables. A comparison with popular approximating functions previously proposed, illustrates the accuracy and flexibility of the new family of interpolatin

Deriving simulators for hybrid Chi models

Abstract-The hybrid Chi language is a formalism for modeling, simulation and verification of hybrid systems. The formal semantics of hybrid Chi allows the definition of provably correct implementations for simulation, verification and realtime control. This paper discusses the principles of deriving an implementation for simulation and verification directly from the semantics, and presents an implementation based on a symbolic solver. The simulator is illustrated by means of a case study

Coordination specification in distributed optimal design of multilevel systems using the χ language

Coordination plays a key role in solving decomposed optimal design problems. Several coordination strategies have been proposed in the multidisciplinary optimization (MDO) literature. They are usually presented as a sequence of statements. However, a precise description of the concurrency in the coordination is needed for large multilevel or non-hierarchic coordination architectures. This article proposes the use of communicating sequential processes (CSP) concepts from concurrency theory for specifying and implementing coordination strategies in distributed multilevel optimization rigorously. CSP enables the description of the coordination as a number of parallel processes that operate independently and communicate synchronously. For this purpose, we introduce elements of the language χ, a CSP-based language that contains advanced data modeling constructs. The associated software toolkit allows execution of the specified coordination. Coordination specification using χ is demonstrated for analytical target cascading (ATC), a methodology for design optimization of hierarchically decomposed multilevel systems. It is shown that the ATC coordination can be compactly specified for various coordination schemes. This illustrates the advantage of using a high-level concurrent language, such as χ, for specifying the coordination of distributed optimal design problems. Moreover, the χ software toolkit is useful in implementing alternative schemes rapidly, thus enabling the comparison of different MDO methods.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46086/1/158_2004_Article_467.pd