Uncertainty in the performance validation of HVAC Systems

A first principles based model approach to AHU cooling coil performance validation is presented. The model of correct operation is compared to that observed in the real system. In the scheme, uncertainty in the measurements and the models is evaluated to generate robust thresholds for decision making. The approach describes the design intent by estimating certain model parameters from design data and expert knowledge. The method systematically incorporates the uncertainty in these parameter estimates in the calculation of the system validation threshold. This yields a definite, transparent indication of system performance to a stated level of confidence. The approach is demonstrated on a cooling coil subsystem installed in an air-handling unit serving zones in a real building

The forces on a fish-inspired unsteady hydrofoil

The flow around an unsteady hydrofoil, undergoing simultaneous heaving and pitching motions which mimic the tail motions of carangiform fish (such as tuna), was investigated using simultaneous particle image velocimetry (PIV) and force measurement. These investigations were performed at Reynolds numbers, based on the foil chord length, in the range of 150

Application of fault detection and diagnosis techniques to automated functional testing

Extensive research in the field of fault detection and diagnosis has produced useful tools and techniques that have been applied to continuously operating building HVAC systems. A few researchers have applied some of these to commissioning of new buildings. This paper reports on a project that adapted or developed models of air-handling unit components and controls and combined them into an automated functional testing tool. Operation of the tool is demonstrated in testing a real air-handling unit

Developing component models for automated functional testing

Reference models developed from first principles and empirical relationships are used to represent correct operation of air-handling units. The models are incorporated into software capable of comparing actual system output measurements with model outputs and detecting deviations from correct operation. Tests of the model-based system with data from a real system, operating with and without introduced faults, are reported

Automated commissioning of HVAC systems using first principle models

Commissioning of HVAC systems has potential for significant improvements in occupant satisfaction, comfort and energy consumption, but is very labour-intensive and expensive as practiced at this time. Previous investigators have capitalized on digital control systems' capability of logging and storing data and of interfacing with external computers for open loop control by developing methods of automated fault detection and diagnosis during normal operation. Some investigators have also considered the application of this technique in commissioning. This thesis investigates the possibility of utilizing first principles and empirical models of air-handling unit components to represent correct operation of the unit during commissioning. The models have parameters whose values can be determined from engineering design intent information contained in the construction drawings and other data available at commissioning time. Quasi-dynamic models are developed and tested. The models are tested against design intent information and also against data from a real system operating without known faults. The results show the models agree well with the measured data except for some false positive indications, particularly in the damper and fan models, during transients. A procedure for estimating uncertainty in the instrumentation and the models is developed. The models are also tested against artificial faults and are able to detect all of the faults. Methods of diagnosing the faults are discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

PIV as a Complement to LDA in the Study of an Unsteady Oscillating Turbulent Flow

Chong Y. Wong, Graham J. Nathan, Richard M Kels

A mitochondria-targeted mass spectrometry probe to detect glyoxals: implications for diabetes

The glycation of protein and nucleic acids that occurs as a consequence of hyperglycaemia disrupts cell function and contributes to many pathologies, including those associated with diabetes and aging. Intracellular glycation occurs following the generation of the reactive 1,2-dicarbonyls methylglyoxal and glyoxal and disruption to mitochondrial function is associated with hyperglycemia. However, the contribution of these reactive dicarbonyls to mitochondrial damage in pathology is unclear due to uncertainties about their levels within mitochondria in cells and in vivo. To address this we have developed a mitochondria-targeted reagent (MitoG) designed to assess the levels of mitochondrial dicarbonyls within cells. MitoG comprises a lipophilic triphenylphosphonium cationic function, which directs the molecules to mitochondria within cells and an o-phenylenediamine moiety that reacts with dicarbonyls to give distinctive and stable products. The extent of accumulation of these diagnostic heterocyclic products can be readily and sensitively quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), enabling changes to be determined. Using the MitoG-based analysis we assessed the formation of methylglyoxal and glyoxal in response to hyperglycaemia in cells in culture and in the Akita mouse model of diabetes in vivo. These findings indicated that the levels of methylglyoxal and glyoxal within mitochondria increase during hyperglycaemia in both cells and in vivo, suggesting that they can contribute to the pathological mitochondrial dysfunction that occurs in diabetes and aging

Coordination as a function of skill level in the gymnastics longswing

The purpose of this study was to investigate the nature of inter-joint coordination at different levels of skilled performance to: (1) distinguish learners who were successful versus unsuccessful in terms of their task performance; (2) investigate the pathways of change during the learning of a new coordination pattern and (3) examine how the learner’s coordination patterns relate to those of experts in the longswing gymnastics skill. Continuous relative phase of hip and shoulder joint motions was examined for longswings performed by two groups of novices, successful (n = 4) and unsuccessful (n = 4) over five practice sessions, and two expert gymnasts. Principal component analysis showed that during longswing positions where least continuous relative phase variability occurred for expert gymnasts, high variability distinguished the successful from the unsuccessful novice group. Continuous relative phase profiles of successful novices became more out-of-phase over practice and less similar to the closely in-phase coupling of the expert gymnasts. Collectively, the findings support the proposition that at the level in inter-joint coordination a technique emerges that facilitates successful performance but is not more like an expert’s movement coordination. This finding questions the appropriateness of inferring development towards a “gold champion” movement coordination

PTV measurement of drag coefficient of fibrous particles with large aspect ratio

The aerodynamic behaviour of long aspect ratio nylon fibrous particles has been investigated experimentally while settling in air under super dilute conditions without any influence of secondary flows and at fibre Reynolds numbers of 0.5-2 based on fibre diameter. A method for laser-based measurement of the orientations and velocities of fibrous particles is also presented. The experimental apparatus employs a two-dimensional Particle Tracking Velocimetry (PTV) to calculate orientation and velocity based on the two end-points. The controlling length scale in the relationship between Reynolds number and drag coefficient was investigated and the equivalent diameter of settling fibre in air was reported. Finally the influence of volume fraction and fibre straightness were assessed. © 2012.Guo Q. Qi, Graham J. Nathan, Richard M. Kels

Psycho-educational interventions for adults with severe or difficult asthma: a systematic review.

types: Journal Article; Research Support, Non-U.S. Gov't; ReviewThis is the author's version of the work that was accepted for publication in the Journal of Asthma. The final version can be accessed via the DOI in this record.Research highlights psychosocial factors associated with adverse asthma events. This systematic review therefore examined whether psycho-educational interventions improve health and self-management outcomes in adults with severe or difficult asthma. Seventeen controlled studies were included. Characteristics and content of interventions varied even within broad types. Study quality was generally poor and several studies were small. Any positive effects observed from qualitative and quantitative syntheses were mainly short term and, in planned subgroup analyses (involving < 5 trials), effects on hospitalizations, quality of life, and psychological morbidity in patients with severe asthma did not extend to those in whom multiple factors complicate management.UK NHS Health Technology Assessment Programm