A Hierarchical Scheduling Model for Dynamic Soft-Realtime System

We present a new hierarchical approximation and scheduling approach for applications and tasks with multiple modes on a single processor. Our model allows for a temporal and spatial distribution of the feasibility problem for a variable set of tasks with non-deterministic and fluctuating costs at runtime. In case of overloads an optimal degradation strategy selects one of several application modes or even temporarily deactivates applications. Hence, transient and permanent bottlenecks can be overcome with an optimal system quality, which is dynamically decided. This paper gives the first comprehensive and complete overview of all aspects of our research, including a novel CBS concept to confine entire applications, an evaluation of our system by using a video-on-demand application, an outline for adding further resource dimension, and aspects of our protoype implementation based on RTSJ

A distributed hard real-time Java system for high mobility components

In this work we propose a methodology for providing real-time capabilities to component-based, on-the-fly reconfigurable, distributed systems. In such systems, software components migrate across computational resources at run-time to allow applications to adapt to changes in user requirements or to external events. We describe how we achieve run-time reconfiguration in distributed Java applications by appropriately migrating servers. Guaranteed-rate schedulers at the servers provide the necessary temporal protection and so simplify remote method invocation management. We describe how we manage overhead and resource utilization by controlling the parameters of the server schedulers. According to our measurements, this methodology provides real-time capability to component-based reconfigurable distributed systems in an effcient and effective way. In addition, we propose a new resource discovery protocol, REALTOR, which is based on a combination of pull-based and push-based resource information dissemination. REALTOR has been designed for real-time component-based distributed applications in very dynamic or adverse environments. REALTOR supports survivability and information assurance by allowing the migration of components to safe locations under emergencies suchas externalattack, malfunction, or lackofresources. Simulation studies show that under normal and heavy load conditions REALTOR remains very effective in finding available resources, and does so with a reasonably low communication overhead.REALTOR 1)effectively locates resources under highly dynamic conditions, 2) has an overhead that is system-size independent, and 3) works well in highlyadverse environments.We evaluate the effectiveness of a REALTOR implementation as part of Agile Objects, an infrastructure for real-time capable, highly mobile Java components

A quality of service based framework for dynamic, dependable systems

There is currently much UK government and industry interest towards the integration of complex computer-based systems, including those in the military domain. These systems can include both mission critical and safety critical applications, and therefore require the dependable communication of data. Current modular military systems requiring such performance guarantees are mostly based on parameters and system states fixed during design time, thus allowing a predictable estimate of performance. These systems can exhibit a limited degree of reconfiguration, but this is typically within the constraints of a predefined set of configurations. The ability to reconfigure systems more dynamically, could lead to further increased flexibility and adaptability, resulting in the better use of existing assets. Current software architecture models that are capable of providing this flexibility, however, tend to lack support for dependable performance. This thesis explores the benefits for the dependability of future dynamic systems, built on a publish/subscribe model, from using Quality of Service (QoS) methods to map application level data communication requirements to available network resources. Through this, original contributions to knowledge are created, including; the proposal of a QoS framework that specifies a way of defining flexible levels of QoS characteristics and their use in the negotiation of network resources, a simulation based evaluation of the QoS framework and specifically the choice of negotiation algorithm used, and a test-bed based feasibility study. Simulation experimentation conducted comparing different methods of QoS negotiation gives a clear indication that the use of the proposed QoS framework and flexible negotiation algorithm can provide a benefit in terms of system utility, resource utilisation, and system stability. The choice of negotiation algorithm has a particularly strong impact on these system properties. The cost of these benefits comes in terms of the processing power and execution time required to reach a decision on the acceptance of a subscriber. It is suggested, given this cost, that when computational resources are limited, a simpler priority based negotiation algorithm should be used. Where system resources are more abundant, however, the flexible negotiation algorithm proposed within the QoS framework can offer further benefits. Through the implementation of the QoS framework within an existing military avionics software architecture based emulator on a test-bed, both the technical challenges that will need to be overcome and, more importantly, the potential viability for the inclusion of the QoS framework have been demonstrated

Optimization of Safety Control System for Civil Infrastructure Construction Projects

Labor-intensive repetitive activities are common in civil construction projects. Construction workers are prone to developing musculoskeletal disorders-related injuries while performing such tasks. The government regulatory agency provides minimum safety requirement guidelines to the construction industry that might not be sufficient to prevent accidents and injuries in a construction site. Also, the regulations do not provide insight into what can be done beyond the mandatory requirements to maximize safety and underscore the level of safety that can be attained and sustained on a site. The research addresses the aforestated problem in three stages: (i) identification of theoretical maximum attainable level of safety, safety frontier, (ii) identification of underlying system inefficiencies and operational inefficiencies, and (iii) identification of achievable level of safety, sustainable safety. The research proposes a novel approach to identify the safety frontier by kinetic analysis of the human body while performing labor-intensive repetitive tasks. The task is a combination of different unique actions, which further involve several movements. For identifying a safe working procedure, each movement frame needs to be analyzed to compute the joint stress. Multiple instances of repetitive tasks can then be analyzed to identify unique actions exerting minimum stress on joints. The safety frontier is a combination of such unique actions. For this, the research proposes to track the skeletal positional data of workers performing different repetitive tasks. Unique actions involved in all tasks were identified for each movement frame. For this, several machine learning techniques were implemented. Moreover, the inverse dynamics principle was used to compute the stress induced by essential joints. In addition to the inverse dynamics principle, several machine learning algorithms were implemented to predict lower back moments. Then, the safety frontier was computed, combining the unique actions exerting minimum stress to the joints. Furthermore, the research conducted a questionnaire survey with construction experts to identify the factors affecting system inefficiencies that are not under the control of the project management team and operational inefficiencies that are under control. Then, the sustainable safety was computed by adding system inefficiencies to the safety frontier and removing operational inefficiencies from observed safety. The research validated the applicability of the proposed methodology in a real construction site. The application of random forest classifier, one-vs-rest classifier, and support vector machine approach were validated with high accuracy (\u3e95%). Similarly, random forest regressor, lasso regression, gradient boosting evaluation, stacking regression, and deep neural network were explored to predict the lower back moment. Random forest regressor and deep neural network predicted the lower back moment with an explained variance of 0.582 and 0.700, respectively. The computed safety frontier and sustainable safety can potentially facilitate the construction sector to improve safety strategies by providing a higher safety benchmark for monitoring, including the ability to monitor postural safety in real-time. Moreover, different industrial sectors such as manufacturing and agriculture can implement the similar approach to identify safe working postures for any labor-intensive repetitive task

The Common Link: An Exploration of the Social Cognitive Dimensions of Meaning-Making in Algebra and the Visual Arts Using a Case Study Approach

It is commonplace to hold that algebra and the visual arts are mutually exclusive activities. In this thesis, an attempt was made to connect how we learn in algebra and the visual arts from the social cognitive perspective proposed by Bandura (1986, 1997). That is, the personal, social, and behavioural dimensions of learning in algebra and the visual arts were considered. Also, the issue of a connection between algebra and the visual arts was tackled by taking into account the most recent advances in cognitive science, like the situated movement, the notion, in a nutshell, that cognition is extended throughout our social relations and practices. Making the connection between, what Snow (1959) called generally the two cultures (cited in Stent, 2001, p. 31) of art and science, has precedence. There have been attempts, as interpreted in this thesis, to consider what learning in the arts and sciences have in common from various quarters, be they philosophical, psychological, or historical. Identifying the link between algebra and the visual arts involved several things. First, the historical context for the schism between our understanding of learning in algebra and the visual arts was considered. Second, a detailed review-cum-analysis of the literature was undertaken, and this yielded the themes upon which the connections between algebra and the visual arts were made. Turning to the fieldwork, four probing case studies were utilized to explore how those in algebra or the visual arts learn in their fields. By analyzing the data from the case studies, pattern regularities between learning in algebra and the visual arts were extracted. Finally, the theoretical and pedagogical consequences of having made the common link between algebra and the visual arts were addressed. Theoretically, by considering the role of, for instance, aesthetics and identity as reasons to pursue algebra or the visual arts, Bandura\u27s (1986, 1997) social cognitive theory was corroborated and enlarged. Practically, recommendations were offered for the pedagogy of algebra and the visual arts