Algorithm development on the use of feedback signals in the context of gasoline HCCI combustion

Homogeneous Charge Compression Ignition (HCCI) combustion is a promising research subject due to its characteristics of high efficiency and low emissions. These are highly desirable, given the global picture of increased energy requirements coupled with serious environmental implications. However, one of the main considerations of HCCI implementation is its control strategies which are not straightforward as in conventional Spark Ignition (SI) or Compression Ignition (Cl) engines. In order for closed loop control strategies to be successful, appropriate signals must be selected. In this research, experimental in-cylinder signals have been collected for pressure and ion current. These have been processed and evaluated as regards their suitability for HCCI control. During this process, physical based models have been developed both for treating experimental data as well as simulating theoretical cases. Using these tools, the behaviour of unstable HCCI operation has also been explored

Computationally inexpensive methods of ion current signal manipulation for predicting the characteristics of engine in-cylinder pressure

Recent research on the use of ion current has focused on matching the characteristics of the in-cylinder pressure, thus avoiding the use of a pressure transducer. This paper explores techniques of calculating these pressure characteristics through the use of simple and computationally inexpensive artificial neural networks. Two neural networks are presented to deduce the in-cylinder pressure from ion current measurements, where one is used to predict the characteristics directly and the other is used to calculate the in-cylinder pressure curve. Experimental results show that both networks give satisfactory results for different purposes. Some engineering implementation issues and the further improvement of the developed techniques are discussed

Using in-cylinder gas internal energy balance to calibrate cylinder pressure data and estimate residual gas amount in gasoline homogeneous charge compression ignition combustion

Data established from pressure measurements in HCCI operation can prove problematic to calibrate due to the presence of TRG, pegging, and thermal shock issues. This article presents an algorithm aimed at using the measurements available on a typical research engine to overcome these issues, yielding properly calibrated results for both averaged and individual cycles

The advance combustion control in a hybrid SI/HCCI engine by using ion current sensing

In a future ‘hybrid mode’ SI/HCCI engine transition between these modes, over the operating map, will play a crucial role. The engine management system must provide a fast and smooth transition between these two modes, hence a new combustion feedback based control system is needed. The aim of this paper is to investigate the use of an ion-current sensor in SI/HCCI engine for direct combustion feedback control. The experimental results obtained, at different speed and loads, show that the estimation of cylinder pressure, through the ion signal, can be performed with high accuracy, and that ion-current has the potential to be a cost effective solution for direct combustion control

An empirical test for cellular automaton models of traffic flow

Based on a detailed microscopic test scenario motivated by recent empirical studies of single-vehicle data, several cellular automaton models for traffic flow are compared. We find three levels of agreement with the empirical data: 1) models that do not reproduce even qualitatively the most important empirical observations, 2) models that are on a macroscopic level in reasonable agreement with the empirics, and 3) models that reproduce the empirical data on a microscopic level as well. Our results are not only relevant for applications, but also shed new light on the relevant interactions in traffic flow.Comment: 28 pages, 36 figures, accepted for publication in PR

Modeling and Simulation of Multi-Lane Traffic Flow

A most important aspect in the field of traffic modeling is the simulation of bottleneck situations. For their realistic description a macroscopic multi-lane model for uni-directional freeways including acceleration, deceleration, velocity fluctuations, overtaking and lane-changing maneuvers is systematically deduced from a gas-kinetic (Boltzmann-like) approach. The resulting equations contain corrections with respect to previous models. For efficient computer simulations, a reduced model delineating the coarse-grained temporal behavior is derived and applied to bottleneck situations.Comment: For related work see http://www.theo2.physik.uni-stuttgart.de/helbing.htm

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Combinations of single-top-quark production cross-section measurements and vertical bar f(LV)V(tb)vertical bar determinations at root s=7 and 8 TeV with the ATLAS and CMS experiments

This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb(-1) at = 7 TeV and 12.2 to 20.3 fb(-1) at = 8 TeV. These combinations are performed per centre-of-mass energy and for each production mode: t-channel, tW, and s-channel. The combined t-channel cross-sections are 67.5 +/- 5.7 pb and 87.7 +/- 5.8 pb at = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 +/- 4.1 pb and 23.1 +/- 3.6 pb at = 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 +/- 1.4 pb at = 8 TeV. The square of the magnitude of the CKM matrix element V-tb multiplied by a form factor f(LV) is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation |V-td|, |V-ts| << |V-tb|. All the |f(LV)V(tb)|(2) determinations, extracted from individual ratios at = 7 and 8 TeV, are combined, resulting in |f(LV)V(tb)| = 1.02 +/- 0.04 (meas.) +/- 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.Peer reviewe