Effect of various ignition timings on combustion process and performance of gasoline engine

This article deals with the effect of the ignition timing on the output parameters of a spark-ignition engine. The main assessed parameters include the output parameters of the engine (engine power and torque), cylinder pressure variation, heat generation and burn rate. However, the article also discusses the effect of the ignition timing on the temperature of exhaust gases, the indicated mean effective pressure, the combustion duration, combustion stability, etc. All measurements were performed in an engine test room in the Department of Technology and Automobile Transport at Mendel University in Brno, on a four-cylinder AUDI engine with a maximum power of 110 kW, as indicated by the manufacturer. To control and change the ignition timing of the engine, a fully programmable Magneti Marelli control unit was used. The experimental measurements were performed on 8 different ignition timings, from 18 CA to 32 CA BTDC at wide throttle open and a constant engine speed (2500 rpm), with a stoichiometric mixture fraction. The measurement results showed that as the ignition timing increases, the engine power and torque also increase. The increase in these parameters is a reflection of higher pressure in the cylinder, the maximum value of which is achieved at a higher ignition timing near top dead centre in thepower stroke. In these conditions we can expect higher engine efficiency. It was also found that the combustion is more stable with a higher value of ignition timing. No significant difference was found in the combustion duration.O

Nonlinear classifiers for ranking problems based on kernelized SVM

Many classification problems focus on maximizing the performance only on the samples with the highest relevance instead of all samples. As an example, we can mention ranking problems, accuracy at the top or search engines where only the top few queries matter. In our previous work, we derived a general framework including several classes of these linear classification problems. In this paper, we extend the framework to nonlinear classifiers. Utilizing a similarity to SVM, we dualize the problems, add kernels and propose a componentwise dual ascent method. This allows us to perform one iteration in less than 20 milliseconds on relatively large datasets such as FashionMNIST

A PDE-constrained optimization approach for topology optimization of strained photonic devices

Recent studies have demonstrated the potential of using tensile-strained, doped Germanium as a means of developing an integrated light source for (amongst other things) future microprocessors. In this work, a multi-material phase-field approach to determine the optimal material configuration within a so-called Germanium-on-Silicon microbridge is considered. Here, an ``optimal" configuration is one in which the strain in a predetermined minimal optical cavity within the Germanium is maximized according to an appropriately chosen objective functional. Due to manufacturing requirements, the emphasis here is on the cross-section of the device; i.e. a socalled aperture design. Here, the optimization is modeled as a non-linear optimization problem with partial differential equation (PDE) and manufacturing constraints. The resulting problem is analyzed and solved numerically. The theory portion includes a proof of existence of an optimal topology, differential sensitivity analysis of the displacement with respect to the topology, and the derivation of first and second-order optimality conditions. For the numerical experiments, an array of first and second-order solution algorithms in function-space are adapted to the current setting, tested, and compared. The numerical examples yield designs for which a significant increase in strain (as compared to an intuitive empirical design) is observed

A semismooth Newton method with analytical path-following for the H1H^1-projection onto the Gibbs simplex

An efficient, function-space-based second-order method for the $H^1$-projection onto the Gibbs-simplex is presented. The method makes use of the theory of semismooth Newton methods in function spaces as well as Moreau-Yosida regularization and techniques from parametric optimization. A path-following technique is considered for the regularization parameter updates. A rigorous first and second-order sensitivity analysis of the value function for the regularized problem is provided to justify the update scheme. The viability of the algorithm is then demonstrated for two applications found in the literature: binary image inpainting and labeled data classification. In both cases, the algorithm exhibits mesh-independent behavior

On M-stationarity conditions in MPECs and the associated qualification conditions

Depending on whether a mathematical program with equilibrium constraints (MPEC) is considered in its original or its enhanced (via KKT conditions) form, the assumed constraint qualifications (CQs) as well as the derived necessary optimality conditions may differ significantly. In this paper, we study this issue when imposing one of the weakest possible CQs, namely the calmness of the perturbation mapping associated with the respective generalized equations in both forms of the MPEC. It is well known that the calmness property allows one to derive so-called M-stationarity conditions. The strength of assumptions and conclusions in the two forms of the MPEC is strongly related with the CQs on the 'lower level' imposed on the set whose normal cone appears in the generalized equation. For instance, under just the Mangasarian-Fromovitz CQ (a minimum assumption required for this set), the calmness properties of the original and the enhanced perturbation mapping are drastically different. They become identical in the case of a polyhedral set or when adding the Full Rank CQ. On the other hand, the resulting optimality conditions are affected too. If the considered set even satisfies the Linear Independence CQ, both the calmness assumption and the derived optimality conditions are fully equivalent for the original and the enhanced form of the MPEC. A compilation of practically relevant consequences of our analysis in the derivation of necessary optimality conditions is provided in the main Theorem 4.3. The obtained results are finally applied to MPECs with structured equilibria

The Effect of the Tractor Tires Load on the Ground Loading Pressure

The contribution, based on the experimental measurement, analyses the issue of a specific pad loading pressure in relation to radial wheel load and tire inflation. Tile inflation in terms of allowed radial load, which we wish to be high as far as possible in terms of the power transmission from the wheels to the ground is important for the field tensile works, on the other hand, the pressure in the tire is closely related to the contact area and ground loading pressure. The obtained results show the following: Michelin Multibib 650/65 R38 tire, inflated to a pressure of 80 kPa has a sufficient reserve in radial load. As the measurement results show, ground loading pressure at the highest load of 36.55 kN, which was used during the measurement, is under the value of 100 kPa, which would mean on loamy soil at a humidity of 17 % that the limit of the ground pressure on the ground has not been exceeded.O

The impact of upper link length on the output parameters of a tractor set

The aim of the article is to find out the impact of the increase in the force in the upper link of a three-point hitch on the performance parameters of the tractor set Claas Arion and the carried plough Pöttinger equipped with a traction roller and the cultivator Väderstad. During aggregation of the tractor with the plough with an average increase in the force in the upper link of a three-point hitch by 25 kN, a decrease of slippage in average by 8.25 %, a decrease in fuel consumption by 1.875 ml / m3 and an increase in effective performance by 0,225 m3 / s were achieved. During aggregation of the same tractor with the carried cultivator with an increase in the force by 40 kN, an average decrease in slippage by 2.64 %, a decrease in effective fuel consumption by 2 l / ha and an increase in effective performance by 0.6 ha / h were achieved. The changes in the observed parameters were demonstrably influenced by the change in the force in the upper link, which was more significantly shown during the aggregation of the tractor with the plough equipped with a traction booster.O