21 resultados para Dynamic systems theory
em University of Queensland eSpace - Australia
Resumo:
The practice of career counseling has been derived from principles of career theory and counseling theory. In recent times, the fields of both career and counseling theory have undergone considerable change. This article details the move toward convergence in career theory, and the subsequent development of the Systems Theory Framework in this domain. The importance of this development to connecting theory and practice in the field of career counseling is discussed.
Resumo:
This paper investigates the input-output characteristics of structural health monitoring systems for composite plates based on permanently attached piezoelectric transmitter and sensor elements. Using dynamic piezoelectricity theory and a multiple integral transform method to describe the propagating and scattered flexural waves an electro-mechanical model for simulating the voltage input-output transfer function for circular piezoelectric transmitters and sensors adhesively attached to an orthotropic composite plate is developed. The method enables the characterization of all three physical processes, i.e. wave generation, wave propagation and wave reception. The influence of transducer, plate and attached electrical circuit characteristics on the voltage output behaviour of the system is examined through numerical calculations, both in frequency and the time domain. The results show that the input-output behaviour of the system is not properly predicted by the transducers' properties alone. Coupling effects between the transducers and the tested structure have to be taken into account, and adding backing materials to the piezoelectric elements can significantly improve the sensitivity of the system. It is shown that in order to achieve maximum sensitivity, particular piezoelectric transmitters and sensors need to be designed according to the structure to be monitored and the specific frequency regime of interest.
Resumo:
Enterprise systems interoperability (ESI) is an important topic for business currently. This situation is evidenced, at least in part, by the number and extent of potential candidate protocols for such process interoperation, viz., ebXML, BPML, BPEL, and WSCI. Wide-ranging support for each of these candidate standards already exists. However, despite broad acceptance, a sound theoretical evaluation of these approaches has not yet been provided. We use the Bunge-Wand-Weber (BWW) models, in particular, the representation model, to provide the basis for such a theoretical evaluation. We, and other researchers, have shown the usefulness of the representation model for analyzing, evaluating, and engineering techniques in the areas of traditional and structured systems analysis, object-oriented modeling, and process modeling. In this work, we address the question, what are the potential semantic weaknesses of using ebXML alone for process interoperation between enterprise systems? We find that users will lack important implementation information because of representational deficiencies; due to ontological redundancy, the complexity of the specification is unnecessarily increased; and, users of the specification will have to bring in extra-model knowledge to understand constructs in the specification due to instances of ontological excess.
Resumo:
An increased incidence of attack has been identified as a major characteristic of the new threat posed by terrorist groups such as al Qaeda. This article considers what such a change means for Western national security systems by examining bow different parts of the system change over time. It becomes evident that Western national security systems are structured on an assumption of comparatively slow state-based threats. In contrast, terrorist franchises operate at a faster pace, are more 'lightweight' and can adapt within the operational and capability cycles of Western governments. Neither network-centric warfare nor an improved assessment of the threat, called for by some, offers a panacea in this regard. Rather, it is clear that not only do Western governments need to adjust their operational and capability cycles, but that they also need a greater diversity of responses to increase overall national security resilience and offer more tools for policy-makers.
Resumo:
Chaotic orientations of a top containing a fluid filled cavity are investigated analytically and numerically under small perturbations. The top spins and rolls in nonsliding contact with a rough horizontal plane and the fluid in the ellipsoidal shaped cavity is considered to be ideal and describable by finite degrees of freedom. A Hamiltonian structure is established to facilitate the application of Melnikov-Holmes-Marsden (MHM) integrals. In particular, chaotic motion of the liquid-filled top is identified to be arisen from the transversal intersections between the stable and unstable manifolds of an approximated, disturbed flow of the liquid-filled top via the MHM integrals. The developed analytical criteria are crosschecked with numerical simulations via the 4th Runge-Kutta algorithms with adaptive time steps.
Resumo:
The present article explores major challenges facing career psychology, specifically within the field of career education. Several issues are identified including the need for more effective links between theory and practice, the movement towards constructivist theories and the related challenges of applying such theories. These issues are explored within the context of the reformulation of career education and through the lens of the constructivist Systems Theory Framework of career development and its applied activity, the My Systems of Career Influences.
Resumo:
In recent years, career theory and practice has been challenged to revise and reinvigorate itself in order to remain relevant in the post- modern world. The most fundamental challenge is to produce an identity for career practice that is congruent with the post-modern world. Career research is facing a similar challenge as it has been dominated by methodologies that emanate out of the positivist worldview of the modern era and has been mainly quantitative in nature. In their recent research, the authors have been examining methodologies that accommodate the tenets of the post-modern world – post-modernism, constructivism and career psychology. This article overviews post- modern considerations by exploring the possibilities offered by the Systems Theory Framework of career development and the 'My System of Career Influence' reflection activity as research tools. Examples of recent research are briefly described.
Resumo:
Computer-based, socio-technical systems projects are frequently failures. In particular, computer-based information systems often fail to live up to their promise. Part of the problem lies in the uncertainty of the effect of combining the subsystems that comprise the complete system; i.e. the system's emergent behaviour cannot be predicted from a knowledge of the subsystems. This paper suggests uncertainty management is a fundamental unifying concept in analysis and design of complex systems and goes on to indicate that this is due to the co-evolutionary nature of the requirements and implementation of socio-technical systems. The paper shows a model of the propagation of a system change that indicates that the introduction of two or more changes over time can cause chaotic emergent behaviour.
Resumo:
Although collaboration manifestly takes place in time, the role of time in shaping the behaviour of collaborations, and collaborative systems, is not well understood. Time is more than clock-time or the subjective experience of time; its effects on systems include differential rates of change of system elements, temporally non-linear behaviour and phenomena such as entrainment and synchronization. As a system driver, it generates emergent effects shaping systems and their behaviour. In the paper we present a systems view of time, and consider the implications of such a view through the case of collaborative development of a new university timetabling system. Teasing out the key temporal phenomena using the notion of temporal trajectories helps us understand the emergent temporal behaviour and suggests a means for improving outcomes.