Modeling Complex Engines as Dynamic Powertrain Members

Engine modeling and simulation have been necessary tools for efficient product development in the automotive industry for some time. The scope of this work is novel engine models, tools, and methods for powertrain research and development. These are packaged in an equation oriented software environment: a toolbox for numerical simulation of complex engines. This toolbox consists of models of the basic physical components in turbocharged diesel engines. Mean value diesel engine models can be built from the modules in the toolbox. In these models the exhaust gas pulsating flow is considered, in order to predict the turbocharging properties in a good way. Engine models can also be built that consider torque irregularities from the individual combustion events. The toolbox provides support for studies of new diesel engine charging systems. The main contribution of this work is the methods developed. They represent a new set up of simulation tools and techniques. The methods developed use an appropriate combination of software, control theory, mechanics, and thermodynamics modeling, vehicle powertrain know- how, and support for the work to be performed to reach a certain goal. The goal is to make design recommendations for improved transient performance of future powertrains. The aim of this work is to provide a platform for engine and powertrain simulation with unique properties that will enable researchers and engineers make these design recommendations. The work includes a discussion about the differential equations and the number of states suitable for modeling thermodynamic modules, such as inlet volumes with and without heat exchange. The exhaust gas energy treatment in mean value engine modeling is discussed, and a novel suggestion for treating the exhaust manifold volume as a physical parameter is provided.It is shown that it might be possible to model some effects concerning the exhaust manifold volume, while maintaining a simple engine model that will run in real time on a regular PC. The potential of highly simplified approaches is explored in order to find good trade off between calculation efficiency and model predictability. There are four complete engine models included in the toolbox, one simple for regular turbo- charged diesel engines, one more advanced for regular turbocharged diesel engines, one for Variable Geometry Turbine (VGT) engines, and one for two-stage charging. The first three of these have been compared with measurements and show good agreement between measured and predicted data

Modeling Complex Engines as Dynamic Powertrain Members

Engine modeling and simulation have been necessary tools for efficient product development in the automotive industry for some time. The scope of this work is novel engine models, tools, and methods for powertrain research and development. These are packaged in an equation oriented software environment: a toolbox for numerical simulation of complex engines. This toolbox consists of models of the basic physical components in turbocharged diesel engines. Mean value diesel engine models can be built from the modules in the toolbox. In these models the exhaust gas pulsating flow is considered, in order to predict the turbocharging properties in a good way. Engine models can also be built that consider torque irregularities from the individual combustion events. The toolbox provides support for studies of new diesel engine charging systems. The main contribution of this work is the methods developed. They represent a new set up of simulation tools and techniques. The methods developed use an appropriate combination of software, control theory, mechanics, and thermodynamics modeling, vehicle powertrain know- how, and support for the work to be performed to reach a certain goal. The goal is to make design recommendations for improved transient performance of future powertrains. The aim of this work is to provide a platform for engine and powertrain simulation with unique properties that will enable researchers and engineers make these design recommendations. The work includes a discussion about the differential equations and the number of states suitable for modeling thermodynamic modules, such as inlet volumes with and without heat exchange. The exhaust gas energy treatment in mean value engine modeling is discussed, and a novel suggestion for treating the exhaust manifold volume as a physical parameter is provided.It is shown that it might be possible to model some effects concerning the exhaust manifold volume, while maintaining a simple engine model that will run in real time on a regular PC. The potential of highly simplified approaches is explored in order to find good trade off between calculation efficiency and model predictability. There are four complete engine models included in the toolbox, one simple for regular turbo- charged diesel engines, one more advanced for regular turbocharged diesel engines, one for Variable Geometry Turbine (VGT) engines, and one for two-stage charging. The first three of these have been compared with measurements and show good agreement between measured and predicted data

Obesity, survival, and hospital costs-findings from a screening project in sweden.

AbstractObjectiveOur aims were to estimate 1) the costs of hospital treatment and 2) the value of lost production due to early death associated with overweight and obese patients, and then to extrapolate the findings to national costs.MethodsWe use regression models to analyze survival, expected number of days in hospital treatment for patients with different body mass index (BMI), and costs with data obtained from screening of 33,196 middle-aged subjects living in Malmö, Sweden, and collected during a 15-year follow-up period. We subsequently scale up costs to national aggregate level using the BMI prevalence data from the screening project to the national population.ResultsThe total excess hospital (somatic, psychiatric) care cost (Swedish krona or SEK) for the national health-care budget, excess as compared to normal weight patients for obese (BMI > 30) and overweight (25 ≤ BMI < 30) was estimated to SEK2155 million per annum (US$269 million, assuming US$1 = SEK8), or about 2.3% of total hospital care costs in Sweden. The corresponding indirect costs due to early death were estimated to SEK2935 million (US$367 million). For males at age 55, the potential hospital costs saving, excluding costs of the intervention that could be gained by an intervention that successfully and safely could alter the weight of an obese individual to become normal weight, was estimated on average to SEK4434 (US$554) per annum.ConclusionHospital treatment costs are found to be higher for obese and overweight patients than for normal weight patients indicating potential cost savings especially on indirect costs by effective, safe and low cost weight-loss intervention