Modelling and predictive control techniques for building heating systems

Model predictive control (MPC) has often been referred to in literature as a potential method for more efficient control of building heating systems. Though a significant performance improvement can be achieved with an MPC strategy, the complexity introduced to the commissioning of the system is often prohibitive. Models are required which can capture the thermodynamic properties of the building with sufficient accuracy for meaningful predictions to be made. Furthermore, a large number of tuning weights may need to be determined to achieve a desired performance. For MPC to become a practicable alternative, these issues must be addressed. Acknowledging the impact of the external environment as well as the interaction of occupants on the thermal behaviour of the building, in this work, techniques have been developed for deriving building models from data in which large, unmeasured disturbances are present. A spatio-temporal filtering process was introduced to determine estimates of the disturbances from measured data, which were then incorporated with metaheuristic search techniques to derive high-order simulation models, capable of replicating the thermal dynamics of a building. While a high-order simulation model allowed for control strategies to be analysed and compared, low-order models were required for use within the MPC strategy itself. The disturbance estimation techniques were adapted for use with system-identification methods to derive such models. MPC formulations were then derived to enable a more straightforward commissioning process and implemented in a validated simulation platform. A prioritised-objective strategy was developed which allowed for the tuning parameters typically associated with an MPC cost function to be omitted from the formulation by separation of the conflicting requirements of comfort satisfaction and energy reduction within a lexicographic framework. The improved ability of the formulation to be set-up and reconfigured in faulted conditions was shown.

The reliability mathematical model of load-sharing parallel systems based on fatigue cumulative damage

Conventional reliability models for parallel systems are not applicable for the analysis of parallel systems with load transfer and sharing. In this short communication, firstly, the dependent failures of parallel systems are analyzed, and the reliability model of load-sharing parallel system is presented based on Miner cumulative damage theory and the full probability formula. Secondly, the parallel system reliability is calculated by Monte Carlo simulation when the component life follows the Weibull distribution. The research result shows that the proposed reliability mathematical model could analyze and evaluate the reliability of parallel systems in the presence of load transfer.

The optical response of nanostructured surfaces and the composite diffracted evanescent wave model

Investigations of the optical response of subwavelength-structure arrays milled into thin metal films have revealed surprising phenomena, including reports of unexpectedly high transmission of light. Many studies have interpreted the optical coupling to the surface in terms of the resonant excitation of surface plasmon polaritons (SPPs), but other approaches involving composite diffraction of surface evanescent waves (CDEW) have also been proposed. Here we present a series of measurements on very simple one-dimensional subwavelength structures to test the key properties of the surface waves, and compare them to the CDEW and SPP models. We find that the optical response of the silver metal surface proceeds in two steps: a diffractive perturbation in the immediate vicinity (2–3 mu m) of the structure, followed by excitation of a persistent surface wave that propagates over tens of micrometres. The measured wavelength and phase of this persistent wave are significantly shifted from those expected for resonance excitation of a conventional SPP on a pure silver surface.

Towards a model for exploring the relationship between managerial decision problems and decision support opportunities

The organisational decision making environment is complex, and decision makers must deal with uncertainty and ambiguity on a continuous basis. Managing and handling decision problems and implementing a solution, requires an understanding of the complexity of the decision domain to the point where the problem and its complexity, as well as the requirements for supporting decision makers, can be described. Research in the Decision Support Systems domain has been extensive over the last thirty years with an emphasis on the development of further technology and better applications on the one hand, and on the other hand, a social approach focusing on understanding what decision making is about and how developers and users should interact. This research project considers a combined approach that endeavours to understand the thinking behind managers’ decision making, as well as their informational and decisional guidance and decision support requirements. This research utilises a cognitive framework, developed in 1985 by Humphreys and Berkeley that juxtaposes the mental processes and ideas of decision problem definition and problem solution that are developed in tandem through cognitive refinement of the problem, based on the analysis and judgement of the decision maker. The framework facilitates the separation of what is essentially a continuous process, into five distinct levels of abstraction of manager’s thinking, and suggests a structure for the underlying cognitive activities. Alter (2004) argues that decision support provides a richer basis than decision support systems, in both practice and research. The constituent literature on decision support, especially in regard to modern high profile systems, including Business Intelligence and Business analytics, can give the impression that all ‘smart’ organisations utilise decision support and data analytics capabilities for all of their key decision making activities. However this empirical investigation indicates a very different reality.

Using parent report to assess bilingual vocabulary acquisition: a model from Irish

This chapter describes the adaptation of a parent report instrument on early language development to a bilingual context. Beginning with general issues of adapting tests to any language, particular attention is placed on the issue of using parents as evaluators of child language acquisition of a minority language in a bilingual context. In Ireland, Irish is the first official language and is spoken by about 65,000 people on a daily basis. However all Irish speakers are bilingual, and children are exposed to the dominant English language at an early age. Using an adaptation of a parent report instrument, 21 typically developing children between 16 and 40 months were assessed repeatedly over two years to monitor their language development. The form allowed parents to document their children’s vocabulary development in both languages. Results showed that when knowledge of both languages was accounted for, the children acquired vocabulary at rates similar to those of monolingual speakers and used translational equivalents relatively early in language development. The study also showed that parents of bilingual children could accurately identify and differentiate language development in both of the child’s languages. Recommendations for adapting and using parent report instruments in bilingual language acquisition contexts are outlined.

The Hurst exponent as an indicator of the behaviour of a model monopile in an ocean wave testing basin

With the importance of renewable energy well-established worldwide, and targets of such energy quantified in many cases, there exists a considerable interest in the assessment of wind and wave devices. While the individual components of these devices are often relatively well understood and the aspects of energy generation well researched, there seems to be a gap in the understanding of these devices as a whole and especially in the field of their dynamic responses under operational conditions. The mathematical modelling and estimation of their dynamic responses are more evolved but research directed towards testing of these devices still requires significant attention. Model-free indicators of the dynamic responses of these devices are important since it reflects the as-deployed behaviour of the devices when the exposure conditions are scaled reasonably correctly, along with the structural dimensions. This paper demonstrates how the Hurst exponent of the dynamic responses of a monopile exposed to different exposure conditions in an ocean wave basin can be used as a model-free indicator of various responses. The scaled model is exposed to Froude scaled waves and tested under different exposure conditions. The analysis and interpretation is carried out in a model-free and output-only environment, with only some preliminary ideas regarding the input of the system. The analysis indicates how the Hurst exponent can be an interesting descriptor to compare and contrast various scenarios of dynamic response conditions.

Investigation into a best practice model for providing an integrated user experience with mobile cloud applications

Mobile Cloud Computing promises to overcome the physical limitations of mobile devices by executing demanding mobile applications on cloud infrastructure. In practice, implementing this paradigm is difficult; network disconnection often occurs, bandwidth may be limited, and a large power draw is required from the battery, resulting in a poor user experience. This thesis presents a mobile cloud middleware solution, Context Aware Mobile Cloud Services (CAMCS), which provides cloudbased services to mobile devices, in a disconnected fashion. An integrated user experience is delivered by designing for anticipated network disconnection, and low data transfer requirements. CAMCS achieves this by means of the Cloud Personal Assistant (CPA); each user of CAMCS is assigned their own CPA, which can complete user-assigned tasks, received as descriptions from the mobile device, by using existing cloud services. Service execution is personalised to the user's situation with contextual data, and task execution results are stored with the CPA until the user can connect with his/her mobile device to obtain the results. Requirements for an integrated user experience are outlined, along with the design and implementation of CAMCS. The operation of CAMCS and CPAs with cloud-based services is presented, specifically in terms of service description, discovery, and task execution. The use of contextual awareness to personalise service discovery and service consumption to the user's situation is also presented. Resource management by CAMCS is also studied, and compared with existing solutions. Additional application models that can be provided by CAMCS are also presented. Evaluation is performed with CAMCS deployed on the Amazon EC2 cloud. The resource usage of the CAMCS Client, running on Android-based mobile devices, is also evaluated. A user study with volunteers using CAMCS on their own mobile devices is also presented. Results show that CAMCS meets the requirements outlined for an integrated user experience.

A small molecule activator of p300/CBP histone acetyltransferase promotes survival and neurite growth in a cellular model of Parkinson’s disease

Parkinson’s disease (PD) is a progressive neurodegenerative disease characterised by motor and non-motor symptoms, resulting from the degeneration of nigrostriatal dopaminergic neurons and peripheral autonomic neurons. Given the limited success of neurotrophic factors in clinical trials, there is a need to identify new small molecule drugs and drug targets to develop novel therapeutic strategies to protect all neurons that degenerate in PD. Epigenetic dysregulation has been implicated in neurodegenerative disorders, while targeting histone acetylation is a promising therapeutic avenue for PD. We and others have demonstrated that histone deacetylase inhibitors have neurotrophic effects in experimental models of PD. Activators of histone acetyltransferases (HAT) provide an alternative approach for the selective activation of gene expression, however little is known about the potential of HAT activators as drug therapies for PD. To explore this potential, the present study investigated the neurotrophic effects of CTPB (N-(4-chloro-3-trifluoromethyl-phenyl)-2-ethoxy-6-pentadecyl-benzamide), which is a potent small molecule activator of the histone acetyltransferase p300/CBP, in the SH-SY5Y neuronal cell line. We report that CTPB promoted the survival and neurite growth of the SH-SY5Y cells, and also protected these cells from cell death induced by the neurotoxin 6-hydroxydopamine. This study is the first to investigate the phenotypic effects of the HAT activator CTPB, and to demonstrate that p300/CBP HAT activation has neurotrophic effects in a cellular model of PD.

The synthetic progestin norgestrel modulates Nrf2 signaling and acts as an antioxidant in a model of retinal degeneration

Retinitis pigmentosa (RP) is one of the most common retinal degenerative conditions affecting people worldwide, and is currently incurable. It is characterized by the progressive loss of photoreceptors, in which the death of rod cells leads to the secondary death of cone cells; the cause of eventual blindness. As rod cells die, retinal-oxygen metabolism becomes perturbed, leading to increased levels of reactive oxygen species (ROS) and thus oxidative stress; a key factor in the secondary death of cones. In this study, norgestrel, an FDA-approved synthetic analog of progesterone, was found to be a powerful neuroprotective antioxidant, preventing light-induced ROS in photoreceptor cells, and subsequent cell death. Norgestrel also prevented light-induced photoreceptor morphological changes that were associated with ROS production, and that are characteristic of RP. Further investigation showed that norgestrel acts via post-translational modulation of the major antioxidant transcription factor Nrf2; bringing about its phosphorylation, subsequent nuclear translocation, and increased levels of its effector protein superoxide dismutase 2 (SOD2). In summary, these results demonstrate significant protection of photoreceptor cells from oxidative stress, and underscore the potential of norgestrel as a therapeutic option for RP.

Development of an antigen-driven colitis model to study presentation of antigens by antigen presenting cells to T cells

Inflammatory bowel disease (IBD) is a chronic inflammation which affects the gastrointestinal tract (GIT). One of the best ways to study the immunological mechanisms involved during the disease is the T cell transfer model of colitis. In this model, immunodeficient mice (RAG-/-recipients) are reconstituted with naive CD4+ T cells from healthy wild type hosts. This model allows examination of the earliest immunological events leading to disease and chronic inflammation, when the gut inflammation perpetuates but does not depend on a defined antigen. To study the potential role of antigen presenting cells (APCs) in the disease process, it is helpful to have an antigen-driven disease model, in which a defined commensal-derived antigen leads to colitis. An antigen driven-colitis model has hence been developed. In this model OT-II CD4+ T cells, that can recognize only specific epitopes in the OVA protein, are transferred into RAG-/- hosts challenged with CFP-OVA-expressing E. coli. This model allows the examination of interactions between APCs and T cells in the lamina propria.

Hypothermia protects brain mitochondrial function from hypoxemia in a murine model of sepsis

Sepsis is commonly associated with brain dysfunction, but the underlying mechanisms remain unclear, although mitochondrial dysfunction and microvascular abnormalities have been implicated. We therefore assessed whether cerebral mitochondrial dysfunction during systemic endotoxemia in mice increased mitochondrial sensitivity to a further bioenergetic insult (hyoxemia), and whether hypothermia could improve outcome. Mice (C57bl/6) were injected intraperitoneally with lipopolysaccharide (LPS) (5 mg/kg; n = 85) or saline (0.01 ml/g; n = 47). Six, 24 and 48 h later, we used confocal imaging in vivo to assess cerebral mitochondrial redox potential and cortical oxygenation in response to changes in inspired oxygen. The fraction of inspired oxygen (FiO2) at which the cortical redox potential changed was compared between groups. In a subset of animals, spontaneous hypothermia was maintained or controlled hypothermia induced during imaging. Decreasing FiO2 resulted in a more reduced cerebral redox state around veins, but preserved oxidation around arteries. This pattern appeared at a higher FiO2 in LPS-injected animals, suggesting an increased sensitivity of cortical mitochondria to hypoxemia. This increased sensitivity was accompanied by a decrease in cortical oxygenation, but was attenuated by hypothermia. These results suggest that systemic endotoxemia influences cortical oxygenation and mitochondrial function, and that therapeutic hypothermia can be protective.