Internal combustion engine heat release calculation using single-zone and CFD 3D numerical models

Abstract The present study deals with a comparative evaluation of a single-zone (SZ) thermodynamic model and a 3D computational fluid dynamics (CFD) model for heat release calculation in internal combustion engines. The first law, SZ, model is based on the first law of thermodynamics. This model is characterized by a very simplified modeling of the combustion phenomenon allowing for a great simplicity in the mathematical formulation and very low computational time. The CFD 3D models, instead, are able to solve the chemistry of the combustion process, the interaction between turbulence and flame propagation, the heat exchange with walls and the dissociation and re-association of chemical species. They provide a high spatial resolution of the combustion chamber as well. Nevertheless, the computation requirements of CFD models are enormously larger than the SZ techniques. However, the SZ model needs accurate experimental in-cylinder pressure data for initializing the heat release calculation. Therefore, the main objective of an SZ model is to evaluate the heat release, which is very difficult to measure in experiments, starting from the knowledge of the in-cylinder pressure data. Nevertheless, the great simplicity of the SZ numerical formulation has a margin of uncertainty which cannot be known a priori. The objective of this paper was, therefore, to evaluate the level of accuracy and reliability of the SZ model comparing the results with those obtained with a CFD 3D model. The CFD model was developed and validated using cooperative fuel research (CFR) engine experimental in-cylinder pressure data. The CFR engine was fueled with 2,2,4-trimethylpentane, at a rotational speed of 600 r/min, an equivalence ratio equal to 1 and a volumetric compression ratio of 5.8. The analysis demonstrates that, considering the simplicity and speed of the SZ model, the heat release calculation is sufficiently accurate and thus can be used for a first investigation of the combustion process

DESIGN FOR LUXURY AUTOMOTIVE HMI SYSTEMS AND DRIVER EXPERIENCES

Luxury is predominantly discussed within marketing, economics and psychology literature, with little research made into the practicalities of designing for luxury products and experiences. This thesis addresses the lack of an evidence base from which to design and virtually prototype luxury automotive HMI (human-machine interaction) systems. The work involved five interconnected studies and two industrial partners: Bentley Motors – manufacturers of luxury automobiles; and the VEC (Virtual Engineering Centre) – a consultancy and R&D organization specialising in digital simulation. In Study 1, a literature review was conducted to build a foundation for the research, providing definitions of luxury and investigating attributes of luxury products, cars and experiences. Four distinct luxury values were identified: financial, symbolic, functional and experiential. Study 2 comprised a benchmarking field study using immersion methods. The HMI system for four luxury cars was analysed to reveal state-of-the-art uses of interaction technologies and control/interaction details. The study provided the researcher with luxury car orientation, whilst uncovering notable tensions in the integration of luxurious design details with advanced interaction and interface technologies. Study 3 comprised the main field research, seeking to deeply probe drivers’ understanding and expectations for HMI systems qualified as providing a luxury experience. Semi-structured in-car interviews were conducted with Bentley Motors employees (n=28). Transcript and video data were processed using grounded theory, verbatim coding and content analysis. The verbatim codes led to a quantitative hierarchy of design criteria for luxury automotive HMI systems. The content analysis provided an exhaustive collection of user constructs that were qualitatively clustered into maps of luxury automotive HMI system and experience dimensions. In combination, the hierarchical design criteria and construct maps provide a set of guidance to assist designers when conceptualizing luxury HMI system interactions and experiences. Study 4 implemented the guidance from Study 3 through a project to ideate a set of 3 luxury HMI system concepts, as inspirational materials for Bentley Motors. A review of new, emerging and unusual (NEU) interaction technologies was made to assist the generation of concepts satisfying the luxury principle of rarity. Finally, in Study 5 a workshop with VEC experts established the plausibility of virtual and augmented reality systems to digitally simulate HMI systems using NEU interactive technologies. Study 5 satisfied a need within Bentley Motors for better understanding of how HMI system design and virtual prototyping could align. The thesis concludes that: (i) user experience goals for luxury automotive HMI systems can be uncovered in a rigorous way through design research; (ii) the design of luxury automotive HMI systems benefits from a new set of a guidance developed from research data without reliance on corporate know-how; and (iii) careful selection of virtual and augmented reality technologies can provide plausible virtual prototyping routes for HMI design concepts

Microscopic universality with dynamical fermions

It has recently been demonstrated in quenched lattice simulations that the distribution of the low-lying eigenvalues of the QCD Dirac operator is universal and described by random-matrix theory. We present first evidence that this universality continues to hold in the presence of dynamical quarks. Data from a lattice simulation with gauge group SU(2) and dynamical staggered fermions are compared to the predictions of the chiral symplectic ensemble of random-matrix theory with massive dynamical quarks. Good agreement is found in this exploratory study. We also discuss implications of our results.Comment: 5 pages, 3 figures, minor modifications, to appear in Phys. Rev. D (Rapid Commun.

Smallest Dirac Eigenvalue Distribution from Random Matrix Theory

We derive the hole probability and the distribution of the smallest eigenvalue of chiral hermitian random matrices corresponding to Dirac operators coupled to massive quarks in QCD. They are expressed in terms of the QCD partition function in the mesoscopic regime. Their universality is explicitly related to that of the microscopic massive Bessel kernel.Comment: 4 pages, 1 figure, REVTeX. Minor typos in subscripts corrected. Version to appear in Phys. Rev.

Parametric level statistics in random matrix theory: Exact solution

An exact solution to the problem of parametric level statistics in non-Gaussian ensembles of N by N Hermitian random matrices with either soft or strong level confinement is formulated within the framework of the orthogonal polynomial technique. Being applied to random matrices with strong level confinement, the solution obtained leads to emergence of a new connection relation that makes a link between the parametric level statistics and the scalar two-point kernel in the thermodynamic limit.Comment: 4 pages (revtex

Vaccination coverage and reasons for non-vaccination in a district of Istanbul

BACKGROUND: In order to control and eliminate the vaccine preventable diseases it is important to know the vaccination coverage and reasons for non-vaccination. The primary objective of this study was to determine the complete vaccination rate; the reasons for non-vaccination and the predictors that influence vaccination of children. The other objective was to determine coverage of measles vaccination of the Measles Immunization Days (MID) 2005 for children aged 9 month to 6 years in a region of Umraniye, Istanbul, Turkey. METHODS: A '30 × 7' cluster sampling design was used as the sampling method. Thirty streets were selected at random from study area. Survey data were collected by a questionnaire which was applied face to face to parents of 221 children. A Chi-square test and logistic regression was used for the statistical analyses. Content analysis method was used to evaluate the open-ended questions. RESULTS: The complete vaccination rate for study population was 84.5% and 3.2% of all children were totally non-vaccinated. The siblings of non-vaccinated children were also non-vaccinated. Reasons for non-vaccination were as follows: being in the village and couldn't reach to health care services; having no knowledge about vaccination; the father of child didn't allow vaccination; intercurrent illness of child during vaccination time; missed opportunities like not to shave off a vial for only one child. In logistic regression analysis, paternal and maternal levels of education and immigration time of both parents to Istanbul were found to influence whether children were completely vaccinated or non-vaccinated. Measles vaccination coverage during MID was 79.3%. CONCLUSION: Efforts to increase vaccination coverage should take reasons for non-vaccination into account

Spectra of massive and massless QCD Dirac operators: A novel link

We show that integrable structure of chiral random matrix models incorporating global symmetries of QCD Dirac operators (labeled by the Dyson index beta=1,2, and 4) leads to emergence of a connection relation between the spectral statistics of massive and massless Dirac operators. This novel link established for beta-fold degenerate massive fermions is used to explicitly derive (and prove the random matrix universality of) statistics of low--lying eigenvalues of QCD Dirac operators in the presence of SU(2) massive fermions in the fundamental representation (beta=1) and SU(N_c >= 2) massive adjoint fermions (beta=4). Comparison with available lattice data for SU(2) dynamical staggered fermions reveals a good agreement

Distribution of the k-th smallest Dirac operator eigenvalue

Based on the exact relationship to Random Matrix Theory, we derive the probability distribution of the k-th smallest Dirac operator eigenvalue in the microscopic finite-volume scaling regime of QCD and related gauge theories.Comment: REVTeX 3.1, 6 pages, 1 figure. Corrected factors in eqs. (16a) and (16c) and very minor typos (v2

Massive chiral random matrix ensembles at beta = 1 & 4 : Finite-volume QCD partition functions

In a deep-infrared (ergodic) regime, QCD coupled to massive pseudoreal and real quarks are described by chiral orthogonal and symplectic ensembles of random matrices. Using this correspondence, general expressions for the QCD partition functions are derived in terms of microscopically rescaled mass variables. In limited cases, correlation functions of Dirac eigenvalues and distributions of the smallest Dirac eigenvalue are given as ratios of these partition functions. When all masses are degenerate, our results reproduce the known expressions for the partition functions of zero-dimensional sigma models.Comment: 6 pages, REVTeX 3.1, no figure; (v2) corrected signatures of c'