Truckload shipments constitute a significant portion of the freight transportation industry. In recent years, truckload industry is facing a serious problem of high driver turn over rate. In this research, we present a mathematical model for multi-zone dispatching method to solve this issue. Multi-zone dispatching is a method in which a service area is divided into many zones. Truckload within a zone is carried by local drivers and the truckload between zones is carried by lane drivers. Apart from reducing the driver tour length to a desirable level, the model for multi-zone also contains some unique constraints to address some issues from the perspectives of the company and the customer. The binary integer program is solved by exact methods. As the problem size increases, exact methods fail quickly. Hence, a construction heuristic within tabu search framework is developed to solve the model. Analysis of various parameters concerned is provided to gain better insights of varied aspects of the problem. Computational results for analysis of parameters and comparison of exact and heuristic methods are provided.

Truckload shipments constitute a significant portion of the freight transportation industry. In recent years, truckload industry is facing a serious problem of high driver turn over rate. In this research, we present a mathematical model for multi-zone dispatching method to solve this issue. Multi-zone dispatching is a method in which a service area is divided into many zones. Truckload within a zone is carried by local drivers and the truckload between zones is carried by lane drivers. Apart from reducing the driver tour length to a desirable level, the model for multi-zone also contains some unique constraints to address some issues from the perspectives of the company and the customer. The binary integer program is solved by exact methods. As the problem size increases, exact methods fail quickly. Hence, a construction heuristic within tabu search framework is developed to solve the model. Analysis of various parameters concerned is provided to gain better insights of varied aspects of the problem. Computational results for analysis of parameters and comparison of exact and heuristic methods are provided.

The purpose of this research is to develop a new approach to estimate the effective leakage area using the inverse modeling process as an alternative to the blower door test. An actual office building, which is the head quarter of Energy Efficiency Hub, was used as an example case in this study. The main principle of the inverse modeling process is comparing the real monitor boiler gas consumption with the result calculated from the EnergyPlus model with a dynamic infiltration rate input to find the best estimation of the parameter of effective leakage area (ELA). This thesis considers only the feasibility of replacing the blower door test with the calibration approach, so rather than attempting an automated calibration process based on inverse modeling we deal with generating a first estimate and consider the role of model uncertainties that would make the proposed method less feasible. There are five steps of the whole process. First, we need to customize our own actual weather data (AMY) needed by the energy model (EnergyPlus model), which can help increase our quality of the result. Second, create the building energy model in EnergyPlus. Third, create a multi-zone model using CONTAM with different ELA estimation of each facade to calculate the dynamic infiltration rate of each ELA estimate. Fourth, input the dynamic infiltration rate got from the CONTAM model to EnergyPlus model and output the boiler energy consumption. Fifth, compare the boiler gas consumption from the model and the real monitor data and find the best match between the two and the corresponding ELA, which gives the best estimate from the whole inverse modeling process. From the simulation result comparison, the best estimation of the total building ELA from the inverse modeling process is the 23437cm2 at 4pa, while the result from the blower door test is 10483cm2 at 4pa. Because of the insufficient information of the building and also the uncertainty of the input parameters, the study has not led to a definite statement whether the proposed calibration of the ELA with consumption data can replace a blower door test to get an equally valid or even better ELA estimate, but it looks feasible. As this this case study is done in a deterministic context, the full feasibility test should be conducted under uncertainty. A first step towards this will talk be discussed in chapter 4.

Det finns ett flertal brandsimuleringsprogram på marknaden som används i olika utsträckning varav ett är Fire Dynamics Simulator (FDS). En av nackdelarna med FDS är att det kan ta mycket tid att göra en brandsimulering. Det finns brandsimuleringsprogram som med stor sannolikhet utför brandsimuleringar snabbare än FDS. För några av dessa brandsimuleringsprogram finns det inte någon dokumentation om hur resultaten som brandsimuleringsprogrammen producerar ställer sig mot det som skulle hända i verkligheten vid en brand, något som kallas att vara valideratdet vill säga programmen är inte validerade. Ett av dessa brandsimuleringsprogram är Multi-Zone Fire Model (MZ-Fire Model). Brandsimuleringsprogrammet MZ-Fire Model bygger på ett multizonkoncept framtaget av Suzuki et al. Multizonkonceptet har validerats i tidigare studier varav ett är en brand i tunnel men även bränder i mindre lokaler har prövats. Det finns utrymme för ökad kunskap om hur multizonkonceptet hanterar bränder i stora rumslokaler då det inte finns någon känd dokumentation kring detta. Det finns i dagsläget inte en enda studie som behandlar brandsimuleringsprogrammet MZ-Fire Model. I rapporten redogörs för simulerande av en brand i 4 olika rum av brandsimuleringsprogrammen MZ-Fire Model och FDS, dess simulerade värden är sedan jämförda mot varandra. / There are a number of fire simulation programs on the market that are used to varying degrees, one of which is Fire Dynamics Simulator (FDS). One of the disadvantages of FDS is that it can take a lot of time to do a fire simulation. There are fire simulation programs that are very likely to perform fire simulations faster than FDS. For some of these fire simulation programs, there is no documentation on how the results produced by the programs compare with what would happen in the event of a real fire, something called to bethat is they are not validated. One of these fire simulation programs is Multi-Zone Fire Model (MZ-Fire Model). The fire simulation program MZ-Fire Model is based on a multi-zone concept developed by Suzuki et al. The multi-zone concept has been validated in previous studies, one of which is a fire in a tunnel but fires in smaller premises have also been tested. There is room for increased knowledge about how the multi-zone concept handles fires in large rooms, as there is no known documentation on this. Currently, there is not a single study dealing with the MZ-Fire Model program. The report describes the simulation of a fire in 4 different rooms by the programs MZ-Fire Model and FDS, its simulated values ​​are then compared against each other.

Chemical kinetics has been widely acknowledged as a fundamental theory in analysis of chemical processes and the corresponding reaction outputs and rates. The study and application of chemical kinetics thus provide a simulation tool to predict many characteristics a chemical process. Oxidation of hydrocarbon fuels applied in internal combustion engines is a complex chemical process involving a great number of a series of chained reaction steps and intermediate and simultaneous species. Symbolic and Numerical description of such a chemical process leads to the development and application of chemical kinetics models. The up-to-date application of chemical kinetics models is to the simulation of autoignition process in internal combustion engines. Multi-zone thermodynamic combustion modelling has been regarded as a functional simulation approach to studying combustion process in IC engines as a decent compromise between computation accuracy and efficiency. Integration of chemical kinetics models into multi-zone models is therefore a potential modelling method to investigate the chemical and physical processes of autoignition in engine combustion. This research work has been therefore concerned with the development, validation and application of multi-zone chemical kinetic engine models in the simulation of autoignition driven combustion in SI and HCCI engines. The contribution of this work is primarily made to establish a mathematical model based on the underlying physical and chemical principles of autoignition of the fuel-air mixture in SI and HCCI engines. Then, a computer code package has been developed to numerically solve the model. The derived model aims at improving the understanding of autoignition behaviour under engine-like conditions and providing an investigative tool to autoignition characteristics. Furthermore, as part of the ongoing program in the research of free piston engines, the results of this work will significantly aid in the investigation and simulation of the constant volume autoignition applied in free piston engines.

A new quasi-dimensional, multi-zone model has been developed to describe the combustion processes occurring inside a dual fuel engine. A dual fuel engine is a compression ignition engine in which a homogeneous lean premixed charge of gaseous fuel and air is ignited by a pilot fuel spray. The atomisation and preparation of the pilot leads to the formation of multiple ignition centres from which turbulent flame fronts develop. The energy release in a dual fuel engine is therefore a combination of that from the combustion of the pilot fuel spray and lean premixed charge. Hence, the dual fuel combustion process is complex, combining elements of both conventional spark and compression ignition engines. The dual fuel engine is beneficial as it can achieve significant reductions in emissions of carbon dioxide (CO2), as well as reducing emissions of oxides of nitrogen (NOx) and particulate matter (PM).

A detailed multi-zone thermodynamic simulation has been developed for the direct-injection (DI) diesel engine combustion process. For the purpose of predicting heterogeneous type combustion systems, the model explores the formation of pre-ignition radicals, start of combustion, and eventual heat release. These mechanisms are described based on the current understanding and knowledge of the diesel engine combustion acquired through advanced laser-based diagnostics. Six zones are developed to take into account the surrounding bulk gas, liquid- and vapor-phase fuel, pre-ignition mixing, fuel-rich combustion products as well as the diffusion flame combustion products. A three-step phenomenological soot model and a nitric oxide emission model are applied based on where and when each of these reactions mainly occurs within the diesel fuel jet evolution process. The simulation is completed for a 4.5 liter, inline four-cylinder diesel engine for a range of operating conditions. Specifically, the engine possesses a compression ratio of 16.6, and has a bore and stroke of 106 and 127 mm. The results suggest that the simulation is able to accurately reproduce the fuel jet evolution and heat release process for conventional diesel engine combustion conditions. The soot and nitric oxide models are able to qualitatively predict the effects of various engine parameters on the engine-out emissions. In particular, the detailed thermodynamics and characteristics with respect to the combustion and emission formation processes are investigated for different engine speed/loads, injection pressures and timings, and EGR levels. The local thermodynamic properties and energy, mass distributions obtained from the simulation offer some fundamental insights into heterogeneous type combustion systems. The current work provides opportunities to better study and understand the diesel engine combustion and emission formation mechanisms for conventional diesel engine combustion modes. The flexible, low computational cost features of this simulation result in a convenient tool for conducting parametric studies, and benefits for engine control and diagnostics.

abstract: The modeling and simulation of airflow dynamics in buildings has many applications including indoor air quality and ventilation analysis, contaminant dispersion prediction, and the calculation of personal occupant exposure. Multi-zone airflow model software programs provide such capabilities in a manner that is practical for whole building analysis. This research addresses the need for calibration methodologies to improve the prediction accuracy of multi-zone software programs. Of particular interest is accurate modeling of airflow dynamics in response to extraordinary events, i.e. chemical and biological attacks. This research developed and explored a candidate calibration methodology which utilizes tracer gas (e.g., CO2) data. A key concept behind this research was that calibration of airflow models is a highly over-parameterized problem and that some form of model reduction is imperative. Model reduction was achieved by proposing the concept of macro-zones, i.e. groups of rooms that can be combined into one zone for the purposes of predicting or studying dynamic airflow behavior under different types of stimuli. The proposed calibration methodology consists of five steps: (i) develop a "somewhat" realistic or partially calibrated multi-zone model of a building so that the subsequent steps yield meaningful results, (ii) perform an airflow-based sensitivity analysis to determine influential system drivers, (iii) perform a tracer gas-based sensitivity analysis to identify macro-zones for model reduction, (iv) release CO2 in the building and measure tracer gas concentrations in at least one room within each macro-zone (some replication in other rooms is highly desirable) and use these measurements to further calibrate aggregate flow parameters of macro-zone flow elements so as to improve the model fit, and (v) evaluate model adequacy of the updated model based on some metric. The proposed methodology was first evaluated with a synthetic building and subsequently refined using actual measured airflows and CO2 concentrations for a real building. The airflow dynamics of the buildings analyzed were found to be dominated by the HVAC system. In such buildings, rectifying differences between measured and predicted tracer gas behavior should focus on factors impacting room air change rates first and flow parameter assumptions between zones second. / Dissertation/Thesis / M.S. Built Environment 2011

This research is related to the control of energy consumption and efficiency in building Heating Ventilation and Air Conditioning (HVAC) systems and is primarily concerned with controlling the function of heating. The main goal of this thesis is to develop a control system that can achieve the following two main control functions: a) detection of unexpected indoor conditions that may result in unnecessary power consumption and b) energy efficiency control regarding optimal balancing of two parameters: the required energy consumption for heating, versus thermal comfort of the occupants. Methods of both orientations were developed in a multi-zone space composed of nine zones where each zone is equipped with a wireless node consisting of temperature and occupancy sensors while all the scattered nodes together form a wireless sensor network (WSN). The main methods of both control functions utilize the potential of the deterministic subspace identification (SID) predictive model which provides the predicted temperature of the zones. In the main method for detecting unexpected situations that can directly affect the thermal condition of the indoor space and cause energy consumption (abnormal situations), the predictive temperature from the SID model is compared with the real temperature and thus possible temperature deviations that indicate unexpected situations are detected. The method successfully detects two situations: the high infiltration gain due to unexpected cold air intake from the external surroundings through potential unforeseen openings (windows, exterior doors, opened ceilings etc) as well as the high heat gain due to onset of fire. With the support of the statistical algorithm for abrupt change detection, Cumulative Sum (CUSUM), the detection of temperature deviations is accomplished with accuracy in a very short time. The CUSUM algorithm is first evaluated at an initial approach to detect power diversions due to the above situations caused by the aforementioned exogenous factors. The predicted temperature of the zone from the SID model utilized appropriately also by the main method of the second control function for energy efficiency control. The time needed for the temperature of a zone to reach the thermal comfort zone threshold from a low initial value is measured by the predicted temperature evolution, and this measurement bases the logic of a control criterion for applying proactive heating to the unoccupied zones or not. Additional key points for the control criterion of the method is the occupation time of the zones as well as the remaining time of the occupants in the occupied zones. Two scenarios are examined: the first scenario with two adjacent zones where the one is occupied and the other is not, and the second scenario with a multi-zone space where the occupants are moving through the zones in a cascade mode. Gama and Pareto probability distributions modeled the occupation times of the two-zone scenario while exponential distribution modeled the cascade scenario as the least favorable case. The mobility of the occupants modeled with a semi-Markov process and the method provides satisfactory and reasonable results. At an initial approach the proactive heating of the zones is evaluated with specific algorithms that handle appropriately the occupation time into the zones.

In the first two chapters of this thesis, the novel method, developed by Mathews and Richards1, for predicting the thermal performance of buildings is introduced. The further enhancement and theoretical clarification of this method is the objective of this thesis. The method is based on a very simple thermo-flow network which models only the most important aspects of heat-flow in buildings. While Mathews and Richards based their network on analysis of the primary aspects of heat-flow in buildings, this thesis derives the simplified model by reduction from a comprehensive model. In this way, the assumptions and limitations is illuminated and the theoretical foundation of the method can be established. As a result of the investigation, a new simplified model with certain theoretical benefits is suggested. In later chapters, the method is extended and refined. Also, a new calculation procedure for finding solutions of the model is presented. In particular the method is extended to include multi-zone heat-flow, structural storage- and variable thermal systems. The new solution method is powerful, simple and efficient. This thesis contributes to the establishment of a viable tool for thermal analysis of buildings. / Dissertation (MEng)--University of Pretoria, 1990. / Mechanical and Aeronautical Engineering / unrestricted