Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis is concerned with the continued development of the Stellenbosch University joint-type knee wear simulator. Initially, information regarding simulators from the literature and commercial entities was collected to provide a knowledge base for current and future work. To further the design of the simulator itself, electronic hardware and software subsystems was developed and evaluated during experimental testing procedures. National Instruments’ cDAQ 9174 data acquisition unit was deemed inadequate for real-time inputoutput control, though proved sufficient for signal capturing purposes in conjunction with LabView software. Furthermore, the various servo-pneumatic sub-circuits’ individual ability to conform to the ISO 14243 series standards’ protocol led to the estimation of measurable performance criteria and the application to a single circuit for illustration. The anterior/posterior actuation circuit in question demonstrated adequate performance for the cases where the piston’s rod was respectively fixed and free to move. In-silico modelling and identification of the relevant servo-pneumatic components then commenced, with the valve and cylinder chamber models yielding adequate estimates of the recorded data. The identified quasi-static friction model proved sensitive to transient effects present within the system, resulting in performance deterioration of the integrated model. Sufficiently accounting for these effects would result in the emergence of the sub-circuit’s model as an invaluable tool in terms of control system development, prediction of the simulator’s behaviour and subsequent design recommendations. Future work therefore concerns improvement, identification and integration of the various sub-circuit models to fully exploit the aforementioned advantages. / AFRIKAANSE OPSOMMING: Hierdie tesis handel oor die voortgesette ontwikkeling van Universiteit Stellenbosch se gewrigstipe knie-afslytingsimulator. Aanvanklik is inligting versamel vanaf literatuur en kommersiële entiteite om sodoende ’n kennisbasis te verskaf vir huidige en toekomstige werk. Elektroniese hardeware en sagteware stelsels is ontwerp en geëvalueer tydens toetsprosedures om die ontwerp van die simuleerder self te verbeter. National Instruments se cDAQ 9174 dataversamelaarseenheid word onvoldoende geag vir intydse inset-uitset beheer, maar wel vir dataversamelingsdoeleindes tesame met LabView sagteware. Die nodigheid om die verskeie servo-pneumatiese sub-stroombane se individuele vermoë om aan te pas by die ISO 14243-reeks se protokol-standaarde te ondersoek, het gelei tot die beraming van meetbare werkverrigtingskriteria en die toepassing daarvan ter illustrasie. Die anterior/posterior stroombaan het voldoende werksverrigting getoon vir studies waar die suier se stang onderskeidelik vas en los was. In-silico modellering en die identifisering van servo-pneumatiese komponente het hierna begin. Die klep en silinderkamer modelle het voldoende skattings gelewer van die gemete data. Die geïdentifiseerde kwasistatiese wrywingsmodel het sensitiwiteit getoon teenoor die oorgangseffekte teenwoordig in die stelsel wat gelei het tot verminderde werksverrigting van die geïntegreerde model. Deur rekening te hou met sulke effekte kan die sub-stelsel se model waardevol wees sover dit beheerstelsel ontwikkeling aangaan, sowel as die voorspelling van die simuleerder se optrede en die daaropvolgende ontwerpsvoorstelle. Toekomstige navorsing kan fokus op die verbetering, identifikasie en integrasie van die verskeie sub-stroombaan modelle om die voorafgenoemde potensiaal ten volle ontgin.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes a Multi-Function Telemetry Input Module (TIM). The TIM module includes a 30 Mbps PCM frame synchronizer, a time code translator/generator, a PCM simulator and a tunable bit synchronizer all on a single PCI card. The module uses a generic architecture including: high density Field Programmable Gate Arrays (FPGAs), look-up table memory, dual port A/B data buffer memory and a full function PCI interface. The FPGA and the logic function of the card are downloadable via the PCI interface. This allows a single module to support many hardware functions in a telemetry front-end. The TIM is an integral part of a PC-based Advanced Telemetry Processing and Display System. This concept for hardware design ushers in a new generation of flexible downloadable telemetry products.

For a stress-sensitive or stress-dependent reservoir, the interactions between its seepage field and in situ stress field are complex and affect hydrocarbon recovery. A coupled geomechanics and fluid-flow model can capture these relations between the fluid and solid, thereby presenting more precise history matchings and predictions for better well planning and reservoir management decisions. A traditional reservoir simulator cannot adequately or fully represent the ongoing coupled fluid-solid interactions during the production because of using the simplified update-formulation for porosity and the static absolute permeability during simulations. Many researchers have studied multiphase fluid-flow models coupled with geomechanics models during the past fifteen years. The purpose of this research is to develop a coupled geomechanics and compositional model and apply it to problems in the oil recovery processes. An equation of state compositional simulator called the General Purpose Adaptive Simulator (GPAS) is developed at The University of Texas at Austin and uses finite difference / finite control volume methods for the solution of its governing partial differential equations (PDEs). GPAS was coupled with a geomechanics model developed in this research, which uses a finite element method for discretization of the associated PDEs. Both the iteratively coupled solution procedure and the fully coupled solution procedure were implemented to couple the geomechanics and reservoir simulation modules in this work. Parallelization, testing, and verification for the coupled model were performed on parallel clusters of high-performance workstations. MPI was used for the data exchange in the iteratively coupled procedure. Different constitutive models were coded into GPAS to describe complicated behaviors of linear or nonlinear deformation in the geomechanics model. In addition, the geomechanics module was coupled with the dual porosity model in GPAS to simulate naturally fractured reservoirs. The developed coupled reservoir and geomechanics simulator was verified using analytical solutions. Various reservoir simulation case studies were carried out using the coupled geomechanics and GPAS modules. / text

This work describes the design and implementation of the Disease Control System DiCon (pronounced [ˈdaɪkɒn]), providing a general framework for solving optimization problems on distributed computer systems. The central aspects of DiCon are discussed, as are decisions made while realizing the system. Several implementation-specific details are highlighted. Real-world applications show the system's flexibility and demonstrate the potential impact DiCon has on public-health decision making. / text

This research investigates the decomposition and burning behaviours of polyurethane foams experimentally and compares the experimental results obtained with the numerical results from the pyrolysis model of Fire Dynamics Simulator, Version 5 (FDS 5). Based on the comparison of model and experimental heat release rates, the accuracy of the pyrolysis model is quantified. In total, this research tested seven polyurethane foams consisting of three non-fire retardant (NFR) and four fire retardant (FR) foams. According to the simultaneous differential scanning calorimetry and thermogravimetric analysis (SDT) experiments, the decomposition behaviour of polyurethane foams under nitrogen environment is represented by two pyrolysis reactions. The first reaction consists of foam decomposition into melts and gases while the second reaction consists of the decomposition of the remaining melts into gases. The kinetic properties which govern the rate of decomposition are the activation energy (E), pre-exponential factor (A), reaction order (n) and heat of reaction (Δhr). Using graphical techniques, E, A and n of the first and second reactions are determined from the thermogravimetric analysis (TGA) results. Through analysing the differential scanning calorimetry (DSC) results, Δhr is determined from the changes in heat flow and sample mass. The thermophysical properties govern the heat transfer through material and these are the thermal conductivity (λ) and specific heat (cp) which are measured experimentally at ambient temperature through the Hot Disk method. Through the Sample Feeding Vertical Cone, the decomposition and melting behaviours of polyurethane foams in a vertical orientation are investigated and the foams tested can be categorised into those which produce melts only after ignition and those which produce melts and char after ignition. The 1-dimensional burning behaviour of foams is obtained from the cone calorimeter experiments. The NFR foams show a change from plateau burning behaviour at low heat flux to two stage burning behaviour at high heat flux while the FR foams consistently show two stage burning behaviour. The combustion property governs the amount of heat released when fuel combusts and this is the effective heat of combustion (Δhc,eff) which is determined from the heat released and mass consumed in the cone experiment. The 1-dimensional burning behaviour is simulated using the pyrolysis model of FDS 5 and two different modelling approaches are considered. The direct method uses the material properties determined experimentally as FDS 5 inputs while the refined method uses the genetic algorithm of Gpyro to refine the kinetic properties which are later used as FDS 5 inputs. The heat release rate of the model and experiment are compared through linear regression analysis which quantifies the accuracy of both methods. The accuracy is defined as the percentage of data points within the boundary of acceptance which is bounded by 25 % of the greatest experimental heat release rate. This assessment method places greater emphasis on the accuracy of developed burning phases and lesser emphasis on the accuracy of initial growth and final decay. The accuracy of the direct method is found to be 56 % while the refined method with estimated kinetic properties achieves a higher accuracy of 75 %. The 2-dimensional burning behaviours are investigated in the foam slab experiments for two different slab thicknesses, 120 and 100 mm. The opposed-flow spread of 120 mm slab is more intense and rapid while for the 100 mm slab, the flame spread is less intense and slow. FDS 5 is used to simulate the experimental results but when the material properties either developed experimentally or refined by Gpyro are used as inputs, the model fails to produce flame spread. This is because FDS 5 does not yet have the features which address the dynamics of foam melting and the reactive nature of the flame. In order to produce flame spread in the model, E of the reactions have been reduced to increase the decomposition rate.

Large opencast coal mines require a complex infrastructure to fulfill production demand and quality values. The distinct specifications required by each customer are achieved by blending adjustments. There is limited control in variability. With only partial information available, operation controllers blend coal by empirical approximation, trying to keep quality between acceptable ranges in order to avoid penalizations, shipment rejections or even contract suspensions. When a decision support system (DSS) centralized in a control room is used for blending control, crew operators visualize enhanced displays of the different sources of information, obtaining a holistic perspective of operations. Using a simulator to reproduce the blending sequence, crew operators can experiment with diverse what-if scenarios and develop blending strategies for an entire working shift, in which they also incorporate their own expertise and the knowledge obtained after interpreting the simulation results. The research focuses on the empirical analysis of the effectiveness of the DSS by studying the performance of crew users in different operating scenarios produced with a simulator. The development of a methodology for measuring this effectiveness and its impact in the quantification of controlling the variability of blending represents a significant contribution in the area of quality improvement for coal production. The effectiveness of the DSS for controlling the blending and load out processes has been numerically measured after experimenting diverse simulated scenarios, proving that the difference between estimated and actual quality delivered is narrower when using a DSS, in comparison with the BTU variability obtained from historical data. The strategies that produced better results in terms of control of coal quality variability, maximization of infrastructure utilization, time spent in making decisions and the minimization of risk for penalizations and rejections, were scored proportionally to the benefits obtained.

This thesis presents a new type of solar simulator and new measurement methods that allow for fast power rating of photovoltaic devices and for fast performance measurements for energy rating and energy yield predictions indoors under controlled, and more realistically simulated outdoor conditions. A novel indoor measurement system for photovoltaic device characterisation based on light emitting diodes (LEDs) as the light sources is described. The solar simulator is capable of reproducing spectral changes seen in natural sunlight, with its intricacies of variable air mass and weather conditions, to a better match than previously possible. Furthermore, it allows measurements under varying light intensity and device temperature. The prototype LED-based solar simulator developed is characterised and its measurement quality is analysed. The system achieves a class BAA solar simulator classification with a class B spectral match, class A light intensity uniformity and a class A temporal stability. It is the first system of its kind that meets the standards of a solar simulator in spectral match to the standard sunlight spectrum and in terms of minimum light intensity. An uncertainty analysis shows that calibration uncertainty for crystalline silicon solar cells is 5% in maximum power with a 95.45% level of confidence. Recommendations for further versions of the solar simulator are given and show potential of reducing this uncertainty down to 2.9% across all measurement spectra (1.8% with a primary calibrated reference cell). A new method for automated power-rating of single- and multi-junction devices is developed. The method uses a unique spectral response measurement and fitting method. It eliminates the need of external measurement equipment for determining spectral response. A simulated characterisation of an amorphous silicon single- and double-junction solar cell show accuracy of better than 0.5% in maximum power. First measurements on the LED-based solar simulator show a measurement error of 4.5% in maximum power, which is due to a lack of measurement feedback of spectral output and measurement irradiance. The first three-dimensional performance matrix for use in photovoltaic energy rating is reported, utilising the LED-based solar simulator. Device characteristics are measured indoors under varying irradiance, temperature and spectrum. A measurement method is detailed and utilised on a crystalline and amorphous silicon solar cell. It allows for the first time a direct investigation of spectral effects on photovoltaic devices under controlled conditions. Results show that amorphous silicon devices are very sensitive to changes in spectrum. Thus, spectral effects should not be neglected in energy yield predictions for such devices.

There is growing evidence that integrating classification and association rule mining can produce more efficient and accurate classifiers than traditional techniques. This thesis introduces a new MapReduce based association rule miner for extracting strong rules from large datasets. This miner is used later to develop a new large scale classifier. Also new MapReduce simulator was developed to evaluate the scalability of proposed algorithms on MapReduce clusters. The developed associative rule miner inherits the MapReduce scalability to huge datasets and to thousands of processing nodes. For finding frequent itemsets, it uses hybrid approach between miners that uses counting methods on horizontal datasets, and miners that use set intersections on datasets of vertical formats. The new miner generates same rules that usually generated using apriori-like algorithms because it uses the same confidence and support thresholds definitions. In the last few years, a number of associative classification algorithms have been proposed, i.e. CPAR, CMAR, MCAR, MMAC and others. This thesis also introduces a new MapReduce classifier that based MapReduce associative rule mining. This algorithm employs different approaches in rule discovery, rule ranking, rule pruning, rule prediction and rule evaluation methods. The new classifier works on multi-class datasets and is able to produce multi-label predications with probabilities for each predicted label. To evaluate the classifier 20 different datasets from the UCI data collection were used. Results show that the proposed approach is an accurate and effective classification technique, highly competitive and scalable if compared with other traditional and associative classification approaches. Also a MapReduce simulator was developed to measure the scalability of MapReduce based applications easily and quickly, and to captures the behaviour of algorithms on cluster environments. This also allows optimizing the configurations of MapReduce clusters to get better execution times and hardware utilization.

This thesis presents a systematic study of human responses to different motions and strategies of car body tilt control regarding ride comfort, working/reading ability and motion sickness on high-speed tilting trains. Experiments with test subjects were performed in a tilting train on curved track as well as in a moving vehicle simulator. The study is multi-disciplinary, combining knowledge and methods from the fields of railway technology, human factors and vestibular science. The main experiment in a tilting train was performed with about 75 seated test subjects, mainly students from Linköping University, making three test runs. In total, these subjects participated in about 210 individual test rides, each with a duration of about 3 hours. Additional tests on comfort disturbances with pushbutton technique have been reported in the project. The simulator experiments used a total of about 75 subjects, making some 320 test rides each of about 30 minutes duration. Test motions consisted of combinations of horizontal (lateral) acceleration and roll acceleration, together with either roll or horizontal acceleration. Rate of change of horizontal acceleration (jerk) and roll velocity were of the same order of magnitude as in a tilting train environment, but horizontal acceleration alone was about half the magnitude. Horizontal and vertical vibrations from a tilting train were added to the test motions, and train seats and interior train noise were also introduced to create a "train feeling". Test designs and methodology have been developed during the course of the experiments. The test subjects answered questionnaires, four times per test run in the train experiment and each 5 minute in the simulator experiment. The investigated variables were: estimated average ride comfort, estimated ability to work or read, and occurrence of symptoms of motion sickness (dizziness, nausea and not feeling well). Lateral and vertical accelerations together with roll motions were monitored and recorded for later evaluation. Results from the train experiments show that the estimated average ride comfort was about 4 on a 5-degree scale, which indicates “good”. Results also show that a reduced tilt compensation of the lateral acceleration while curving together with a reduced tilt velocity of the car body reduce the provocation of motion sickness. However, a reduction in tilt compensation may produce an increased number of comfort disturbances due to lateral acceleration in the car body. Regression analysis shows that motion doses from roll acceleration may be used to predict the incidence of motion sickness. The simulator experiments show that the primary sources of provocation of nausea and motion sickness are the motion doses from roll and lateral acceleration in the horizontal plane. The study proposes a hypothesis and a model of provocation of motion sickness. It is shown that motion sickness has a time decay, or leakage. A model for this leakage is proposed. The determinative types of motion for provocation of nausea and motion sickness in tilting trains are identified and future tilting train and/or simulator experiments are proposed in order to further investigate their influence. / <p>NR 20140805</p>

This thesis describes the simulation of the IBM SYSTEM/7. The research leading to this thesis involved the development of a PL/I computer program that runs on an IBM 360/50 computer and simulates the IBM SYSTEM/7. Various methods of simulation are examined and guidelines for computer simulation of another computer are established. The SYSTEM/7 simulator (SIM/7) is the heart of this thesis. SIM/7 simulates the IBM SYSTEM/7 entirely with software as opposed to an emulator which involves the combined use of hardware and software to perform the simulation process. This thesis contains a general introduction to computer simulation, reason for simulation, a user's guide for SIM/7 and a definition of the SYSTEM/7 processor using the Vienna Definition Language.