No description available.

To meet the increasing demand on control precision in industrial forklifts, physical modelling of the lifting system has been combined with parameter estimations from data. A number of different controllers have been evaluated in terms of their ability to achieve a load independent lifting speed. The model and controller performance as well as stability properties were evaluated in simulations, and the most promising controller was implemented on the real system. Especially the electric motor turned out to be difficult to model, and therefore experimental data was used to approximate some parts of it. This, along with some friction parameters that had to be estimated caused a slight loss in model generality. An observer (Extended Kalman filter) was used to estimate the unknown states, including the velocity of the forks. The simulated performance of the MPC controller was slightly better than the PID controller, except for a bigger overshoot when starting from a turned off motor. The PID controller also handles model errors better, because of its integral action. Due to the simplicity in relation to performance, only the PID controller was implemented on the forklift. The model turned out to perform well, but not well enough to estimate the lifting height accurately. The PID controller worked as intended and it could therefore be concluded that a more advanced control algorithm, such as an MPC controller, is not necessary for this system.

Functionally, a vertically split fovea should confer an advantage to the processor. Visual stumuli arriving to each eye would be vertically split and the two parts sent to different hemispheres, obeying the crossed nature of the visual pathways. I test the prediction of a functional advantage for the separate lateralisation of text processing from the two eyes. I explore this hypothesis by means of psycholinguistic experimentation and cognitive modelling. I employed a haploscope to show foveated text to the two eyes separately, controlling for location and presentation duration, and guaranteeing that each eye could not see the other eye's stimuli. I carried out a series of experiments, based on this novel paradigm, to explore the effects of a vertically split fovea on correctness of word perception. The experiments showed: (i) words presented exclusively to the contralateral hemifoveas are more correctly reported than words presented exclusively to the ipsilateral hemifoveas; (ii) the same full word shown to both eyes and available for fusion led to better perception; (iii) word endings with fewer type-count neighbours were more accurately reported, as were beginnings with larger type-count neighbours; (iv) uncrossed-eye stumuli were better perceived than crossed-eye stimuli; (v) principled roles in a model of isolated word recognition for lexical and sublexical neighbourhood statistics, syllabicity, hemispheric fine- and coarse-coding differences, sex of the reader, handedness, left and right eye, and visual pathways. Finally, I propose a connectionist model of visual word recognition that incorporates these findings and is a basis for further exploration.

In military training contexts, fast and long term decisions are intermixed where survival and security are prioritized. Simulation-based training, here applied to ground patrols in Afghanistan, can provide preparation for mission critical and life critical operations prior to exposure to real danger. Optimising the effectiveness of simulation-based training raises the need for more detailed representations of the competences required, both for simulation design and for evaluating simulation effectiveness. These needs are here considered in terms of three research questions . The first research question asks how objects trigger dialogue in observational tasks. Eye gaze tracking and recorded dialogue provide a foundation for proposing the cognitive operational structures behind how objects and dialogue are structured when people work together when collaborating in simulation-based training sessions. The objects are tracked along with related observational tasks and the communication between people in a team in ground vehicles and in the Tactical Operations Centre (TOC). The second research question asks how the results of simulation-based training for emergency situations can be described and evaluated. The last research question asks how debriefing and learning create and refine cognitive comprehension, the competency developed in a group. Low level visual cognition in a tactical environment is explored using an eye gaze tracking system integrated with a simulation environment. The integrated system has been evaluated, its accuracy characterized, and the system was then used to evaluate hypotheses related to visual queuing and target selection. The research questions are then explored more broadly based upon two exploratory field studies of simulation-based training sessions held for military staff before leaving for ISAF in Afghanistan. Study methods here include eye gaze tracking, video and audio recording, behavioral observation and retrospective questions. The field studies were conducted at the Swedish Life Guard Regiment sub-departments: International Training Unit(IntUtbE), pre-deployment training for Peace support operations, and Swedish Armed Forces International Centre (SWEDINT), with their Simulation, Modeling and Practical Platform. Based upon data obtained in the field studies, cognitive models of decision processes involved in operational task performance are developed to provide a basis for answering the research questions. Cognitive modelling begins with the Belief, Desire and Intension (BDI) model. This model is then modified in several steps to cover different levels of decision making revealed by the field studies, including an intrapersonal and organizational layer, an educational layer, a layer where objects are build into the algorithm as a basis for purposive behavior, and finally a team competency layer built largely during debriefing sessions. These models can be used to evaluate simulation-based training effectiveness, to provide feedback both in real time and retrospectively to trainees and teams, and potentially could be used in operational systems to provide real-time information about individual and group state during operations, for decision enhancement, and potentially as elements of the implementation of automated operational forces.

In the Canterbury region, New Zealand, water is a contentious issue when irrigation and dairy farming are involved. The Canterbury region accounts for 70% of the total irrigated land area in New Zealand and is one of the most productive agricultural regions. Traditionally, water has been seen as an abundant resource, but growing water demands are now outstripping the supply of water, hence threatening the sustainability of agricultural productivity. In the long term, this problem may worsen as a result of climate change, which is predicted to increase water demands and reduce supply in many parts of Canterbury. In the recent and on-going expansion of irrigation systems, modern sprinkler irrigation methods, namely centre pivot and lateral spray irrigation technology, have replaced the old border-dyke systems. This has been due to the need to increase irrigation flexibility and efficiency to guarantee pasture growth for dairy production in dry periods. This conversion has resulted in a reduction of windbreaks to 2 m heights or sometimes led to 100% removal of windbreaks so as to accommodate centre pivot or linear move irrigation systems. Removal of windbreaks or reduction of windbreak height may increase wind speed across a field. Both spray evaporation loss and evapotranspiration are a function of wind speed. Hence, any increase in wind speed may lead to an increase in irrigation requirements. There is little information currently available on outlining how reduction of windbreak height or the complete removal of windbreaks affects efficiency in water application. Thus, this research was done to quantify the effects of windbreaks on water savings under sprinkler irrigation systems in the Canterbury region under various climatic conditions. The research was done in three major steps: (1) spray evaporation loss (SEL)was measured under various climatic conditions for two typical spray nozzles(Nelson Irrigation Corporation Rotator R3000 and Spinner S3000 nozzles) to develop SEL prediction models; (2) wind speed reduction behind windbreaks was quantified for fields under various wind conditions; and (3) the effects of wind speed reduction by windbreaks was modelled for evapotranspiration, spray evaporation loss and irrigation. The results showed that an increase of wind speed, due to the removal of windbreaks or a reduction of height of windbreaks, leads to an increase in evapotranspiration and spray evaporation losses in irrigated agriculture. For the size of the fields considered in this study which are 80 m by 80 m (Site 1 with medium porosity windbreaks) and 120 m by 120 m (Site 2 with low porosity windbreaks), extra irrigation water of up to 14% is needed in one growing season when windbreaks are reduced to 2 m in height. When windbreaks are completely removed from the field, extra irrigation water of up to 38% and 64% is needed when irrigating using the Rotator R3000 nozzle and the Spinner S3000 nozzle, respectively. Thus, reduction of water resource use can be achieved in irrigated agriculture if irrigation systems can be designed to operate under existing windbreaks. Other savings can follow, from reduced requirements for pumping, fuel and labour costs. Lastly, with future climate change projections showing that the Canterbury region will get windier and hotter, windbreaks can help mitigate water losses associated with sprinkler irrigation

Road traffic networks offer a particularly challenging research subject to the control community. The traffic congestion around big cities is constantly increasing and is now becoming a major problem. However, the dynamics of a road network exhibit some complex behaviours such as nonlinearities, delays and saturation effects that prevent the use of some classical control algorithms. This thesis presents different models and control algorithms used for road traffic networks. The dynamics are represented using a "fluid-flow" approach. This leads to a system of quasi-linear hyperbolic partial differential equations which represents the behaviour of the drivers on each road. The boundary conditions are represented by a set of algebraic relations describing the behaviour of the drivers at the junctions. Two models with different complexities are introduced and their properties analysed. Different control algorithms are presented. One method is focused on the steady state case and intends to minimise a "sustainable cost" function. This function takes into account a time cost, the pollution and the accident risk. Two other methods which are able to deal with transient effects are also presented. The first one is a routing strategy expressing how to spread the traffic flow between two paths leading to the same destination. The second one is a ramp metering strategy using linear feedback.

<p>This licentiate thesis deals mainly with modelling ofturbocharged SIengines. A model of a 4-cylinder engine was runin both steady state and transient conditions and the resultswere compared to measured data. Large differences betweenmeasurements and simulations were detected and the reasons forthis discrepancy were investigated. The investigation showedthat it was the turbocharger turbine model that performed in anon-optimal way. To cope with this, the turbine model containedparameters, which could be adjusted so that the model resultsmatched measured data. However, it was absolutely necessary tohave measured data to match against. It was thus concluded thatthe predictivity of the software tool was too poor to try topredict the performance of various boosting systems. Thereforemeans of improving the modelling procedure were investigated.To enable such an investigation a technique was developed tomeasure the instantaneous power output from, and efficiency of,the turbine when the turbocharger was used on the engine.</p><p>The project’s initial aim was to predict, throughsimulations, the best way to boost a downsized SI-engine with avery high boost-pressure demand. The first simulation run on astandard turbocharged engine showed that this could not be donewith any high accuracy. However, a literature study was madethat presents various different boosting techniques that canproduce higher boost pressure in a larger flow-range than asingle turbocharger, and in addition, with smallerboost-pressure lag.</p><p><b>Key words:</b>boosting, turbocharging, supercharging,modelling, simulation, turbine, pulsating flow, unsteadyperformance, SI-engine, measurement accuracy</p>

Hyperglycaemia in critical care is common and has been linked to increased mortality and morbidity. Tight control of blood glucose concentrations to more normal levels can significantly reduce the negative outcomes associated with hyperglycaemia. However, hypoglycaemia and glycaemic variability have also been independently shown to increase mortality in critically ill patients. Further complicating the matter, critically ill patients exhibit high inter- and intra patient metabolic variability and thus consistent, safe control of glycaemia has proved very difficult. Model-based and model-derived tight glycaemic control methods have shown significant ability to provide very tight control with little or no hypoglycaemia in the intensive care unit (ICU). The model-based control practised in the Christchurch Hospital ICU uses a physiological model that relies on a single, time-varying parameter, SI, to capture the patient-specific glycaemic response to insulin. As an identified parameter, SI is prone to also capturing other, unintended, dynamics that add variability on multiple timescales. The objective of this research was to enable enhanced glycaemic control by addressing this variability of the SI parameter through better modelling and implementation. An improved model of insulin secretion as a function of blood glucose concentration was developed using data collected from a recent study at the Christchurch Hospital ICU. Separate models were identified for non-diabetic patients and diagnosed, or suspected type II diabetic patients, with R2 = 0.61 and 0.69, respectively. The gradients of the functions identified were comparable to data published in a number of other studies on healthy and diabetic subjects. The transcapilliary diffusion (nI) and cellular clearance (nC) rate parameters were optimised using data from published microdialysis studies. Interactions between these key parameters determine maximum interstitial insulin concentrations available for glucose disposal, and thus directly influence SI. The optimal values of these parameters were determined to be nI = nC = 0.0060 1/min. Models of endogenous glucose production (EGP), as functions of blood glucose concentration and time, were assessed. These models proved unsatisfactory due to difficulties in identifying reliable functions with the available data set. Thus, it was determined that EGP should continue to be treated as a population constant, except during real-time glycaemic control, where the value may be adjusted temporarily to ensure valid SI values. The first 24 hours of ICU stay proved to be a period of significantly increased SI variability, both in terms of hour-to-hour changes and longer-term evolution of level. This behaviour was evident for the entire study cohort as a whole and was particularly pronounced during the first 12-18 hours. The subgroup of cardiovascular surgery patients, in which there was sufficient data for analysis, mirrored the results of the whole cohort, but was found to have even lower and more variable SI. Glucocorticoid steroids were also found to be associated with clinically significant reductions in overall level and increases in hour-to-hour variability of SI. To manage variability caused by factors external to the physiological model, the use of several stochastic models was proposed. Using different models for the early part of ICU stay and for different diagnostic subgroups as well as when patients were receiving certain drug therapies would permit control algorithms to reduce the impact of the SI variability on outcome glycaemia. The impact of measurement timing and BG concentration errors on the variability of SI was assessed. Results indicated that the impact of both sources of errors on SI level was unlikely to be clinically significant. The impact of BG sensor errors on hour-to-hour SI variability was more pronounced. Understanding the effect of sensor and timing errors on SI allows their impact to be reduced by using the 5-95 percentile forecast range of stochastic models during glycaemic control. The performance of the model incorporating the proposed insulin kinetic parameters and secretion enhancements was validated for clinical glycaemic control and virtual trial purposes. This validation was conducted by self- and cross validation on a cohort independent to that with which the model was developed. The use of multiple stochastic models to reduce the impact of this extrinsic variability during glycaemic control was validated using virtual trials.

This thesis investigates novel methodologies for modelling, simulation and control of gas turbines using ANNs. In the field of modelling and simulation, two different types of gas turbines are modelled and simulated using both Simulink and neural network based models. Simulated and operational data sets are employed to demonstrate the capability of neural networks in capturing complex nonlinear dynamics of gas turbines. For ANN-based modelling, the application of both static (MLP) and dynamic (NARX) networks are explored. Simulink and NARX models are set up to explore both steady-state and transient behaviours. To develop an offline ANN-based system identification methodology for a low-power gas turbine, comprehensive computer program code including 18720 different ANN structures is generated and run in MATLAB to create and train different ANN models with feedforward multi-layer perceptron (MLP) structure. The results demonstrate that the ANN-based method can be applied accurately and reliably for the system identification of gas turbines. In this study, Simulink and NARX models are created and validated using experimental data sets to explore transient behaviour of a heavy-duty industrial power plant gas turbine (IPGT). The results show that both Simulink and NARX models successfully capture dynamics of the system. However, NARX approach can model gas turbine behaviour with a higher accuracy compared to Simulink approach. Besides, a separate complex model of the start-up operation of the same IPGT is built and verified by using NARX models. The models are set up and verified on the basis of measured time-series data sets. It is observed that NARX models have the potential to simulate start-up operation and to predict dynamic behaviour of gas turbines. In the area of control system design, a conventional proportional-integral-derivative (PID) controller and neural network based controllers consisting of ANN-based model predictive (MPC) and feedback linearization (NARMA-L2) controllers are designed and employed to control rotational speed of a gas turbine. The related parameters for all controllers are tuned and set up according to the requirements of the controllers design. It is demonstrated that neural network based controllers (in this case NARMA-L2) can perform even better than conventional controllers. The settling time, rise time and maximum overshoot for the response of NARMA-L2 is less than the corresponding factors for the conventional PID controller. It also follows the input changes more accurately than the PID. Overall, it is concluded from this thesis that in spite of all the controversial issues regarding using artificial neural networks for industrial applications, they have a high and strong potential to be considered as a reliable alternative to the conventional modelling, simulation and control methodologies. The models developed in this thesis can be used offline for design and manufacturing purposes or online on sites for condition monitoring, fault detection and trouble shooting of gas turbines.

No description available.