57 research outputs found
Construction and analysis of causally dynamic hybrid bond graphs
Engineering systems are frequently abstracted to models with discontinuous behaviour (such as a switch or contact),
and a hybrid model is one which contains continuous and discontinuous behaviours. Bond graphs are an established
physical modelling method, but there are several methods for constructing switched or ‘hybrid’ bond graphs, developed
for either qualitative ‘structural’ analysis or efficient numerical simulation of engineering systems. This article proposes a
general hybrid bond graph suitable for both. The controlled junction is adopted as an intuitive way of modelling a discontinuity in the model structure. This element gives rise to ‘dynamic causality’ that is facilitated by a new bond graph notation. From this model, the junction structure and state equations are derived and compared to those obtained by
existing methods. The proposed model includes all possible modes of operation and can be represented by a single set
of equations. The controlled junctions manifest as Boolean variables in the matrices of coefficients. The method is more
compact and intuitive than existing methods and dispenses with the need to derive various modes of operation from a
given reference representation. Hence, a method has been developed, which can reach common usage and form a platform for further study
Short Term Gain, Long Term Pain:Informal Job Search Methods and Post-Displacement Outcomes
This paper examines the role of informal job search methods on the labour market outcomes of displaced workers. Informal job search methods could alleviate short-term labour market difficulties of displaced workers by providing information on job opportunities, allowing them to signal their productivity and may mitigate wage losses through better post-displacement job matching. However if displacement results from reductions in demand for specific sectors/skills, the use of informal job search methods may increase the risk of job instability. While informal job search methods are associated with lower wage losses, they lead to increased job instability and increased risk of subsequent job displacement
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