Search results for "Bust"
showing 10 items of 1000 documents
A memetic approach to discrete tomography from noisy projections
2010
Discrete tomography deals with the reconstruction of images from very few projections, which is, in the general case, an NP-hard problem. This paper describes a new memetic reconstruction algorithm. It generates a set of initial images by network flows, related to two of the input projections, and lets them evolve towards a possible solution, by using crossover and mutation. Switch and compactness operators improve the quality of the reconstructed images during each generation, while the selection of the best images addresses the evolution to an optimal result. One of the most important issues in discrete tomography is known as the stability problem and it is tackled here, in the case of no…
Propellant non-steady burning effects on controllable solid rocket motor internal ballistics
2009
An analysis of the unsteady non-linear behavior of the controllable solid propellant rocket motor (CSRM) consequent to rapid and relevant nozzle operation is presented. The study includes a development of a non-linear unsteady combustion model able to handle relevant and rapid chamber pressure changes typical of CSRMs. The CSRM nonlinear unsteady model is implemented according to a main solver - sub models architecture and uses different time scales. The formulation of the combustion gas mass flow rate is developed considering the propellant density, the unsteady combustion, the regression of the combustion surface and the outflow through the variable nozzle. The grain surface involved in t…
Further Experiments on the Effect of Bulk In-Cylinder Temperature in the Pressurized Motoring Setup Using Argon Mixtures
2020
Mechanical friction and heat transfer in internal combustion engines have long been studied through both experimental and numerical simulation. This publication presents a continuation study on a Pressurized Motoring setup, which was presented in SAE paper 2018-01-0121 and found to offer robust measurements at relatively low investment and running cost. Apart from the limitation that the peak in-cylinder pressure occurs around 1 DegCA BTDC, the pressurized motoring method is often criticized on the fact that the gas temperatures in motoring are much lower than that in fired engines, hence might reflect in a different FMEP measurement. In the work presented in SAE paper 2019-01-0930, Argon w…
An Experimental Study of In-Cylinder Heat Transfer from a Pressurized Motored Engine with Varying Peak Bulk Gas Temperatures
2022
The variation of in-cylinder heat transfer with parameters such as engine speed, air-to-fuel ratio, coolant temperature and compression ratio were frequently studied in classical research. These experimentally-obtained relationships are important for improving in-cylinder heat transfer models, essential in developing CO2 reducing strategies. In this publication, a 2.0 liter compression ignition engine was tested in the pressurized motored configuration. This developed experimental setup allowed testing of the engine at speeds ranging between 1400 rpm and 3000 rpm, with peak in-cylinder gas pressures from 40 bar to 100 bar. The engine was motored using different gas compositions chosen speci…
An Effective Method to Model the Combustion Process in Spark Ignition Engines
2022
A numerical simulation is a fundamental tool in the design and optimization procedure of an Internal Combustion (IC) engine; since combustion is the process that mostly influences the engine performance, efficiency and emissions, an effective combustion submodel is fundamental. A simple, nonpredictive way to simulate the combustion evolution is to implement a mathematical function that reproduces the mass fraction burned (MFB) profile that is characterized by a sigmoidal trend; the most used for this purpose is the Wiebe function. In this article the authors propose a different mathematical model, a Dose-Response (DR) type function that shows some benefits when compared to the Wiebe functio…
Simulation Study on the Use of Argon Mixtures in the Pressurized Motored Engine for Friction Determination
2020
Mechanical friction and heat transfer in internal combustion engines are two highly researched topics, due to their importance on the mechanical and thermal efficiencies of the engine. Despite the research efforts that were done throughout the years on both these subjects, engine modeling is still somewhat limited by the use of sub-models which do not fully represent the phenomena happening in the engine. Developing new models require experimental data which is accurate, repeatable and which covers wide range of operation. In SAE 2018-01-0121, the conventional pressurized motored method was investigated and compared with other friction determination methods. The pressurized motored method p…
Realistic Steady State Performance of an Electric Turbo-Compound Engine for Hybrid Propulsion System
2022
The efficiency of Hybrid Electric Vehicles (HEVs) may be substantially increased if the unexpanded exhaust gas energy is efficiently recovered and employed for vehicle propulsion. This can be accomplished employing a properly designed exhaust gas turbine connected to a suitable generator whose output electric energy is stored in the vehicle storage system; a new hybrid propulsion system is hence delineated, where the power delivered by the main engine is combined to the power produced by the exhaust gas turbogenerator: previous studies, carried out under some simplifying assumptions, showed potential vehicle efficiency increments up to 15% with respect to a traditional turbocharged engine. …
A mesh less approch based upon Radial basis function Hermite collocation method for predicting the cooling and the freezing times of foods
2005
This work presents a meshless numerical scheme for the solution of time dependent non linear heat transfer problems in terms of a radial basis function Hermite collocation approach. The proposed scheme is applied to foodstuff's samples during freezing process; evaluation of the time evolution of the temperature profile along the sample, as well as at the core, is carried out. The moving phase-change zone is identified in the domain and plotted at several timesteps. The robustness of the proposed scheme is tested by a comparison of the obtained numerical results with those found using a Finite Volume Method and with experimental results.