Nonlinear modelling and control of a common rail injection system for diesel engines

Modern trends in designing mechatronic systems call for a synergic design of the separated subsystems (mechanic, electronic parts, control modules, etc.) concurring to the overall performance. Following this point of view, this paper presents a control oriented model and a nonlinear control design for a Common Rail injection system. First a model is developed, which is tuned in a virtual simulation environment, representing the injection system in details in a reliable replication of reality. Then a sliding mode control is developed. Both the model of the injection process and of the control law are validated by a virtual detailed simulation environment. The prediction capability of the model and the control efficiency are clearly shown.     

Buckling of laminated plates - A simple finite element based on higher-order theory

A four-noded rectangular element with seven degrees of freedom at each node is developed for buckling analysis of laminated plate structures having any number of layers with a constant thickness of individual layers. The displacement model is so chosen that it can explain adequately the parabolic distribution of transverse shear stresses and the non-linearity of in-plane displacements across the thickness. A geometrical stiffness matrix is developed using in-plane stresses. A wide range of plates from thick to thin are examined under uniaxial loading conditions. The results are compared with the existing analytical and numerical solutions. The present formulations confirm its applicability for buckling analysis of a wide range of plates.     

The application of Hölder exponent to traffic congestion warning

In this paper, we applied multifractal modeling techniques to analyze the traffic data collected from the Beijing Yuquanying. The results indicated that multifractal characteristics obviously exist in the traffic system; the degree of fractality of these traffic data tends to increase as the traffic system becomes congested; the Hölder exponent that measures the local rate of fractality may be used as indicators to predict the presence of the traffic congestion.     

A highly specific polyclonal antiserum to the environmental contaminant 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (p,p′-DDT)

A very selective polyclonal antiserum against 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (p,p′-DDT) was obtained by a careful choice of the haptenic structure (2,2-bis(4-chlorophenyl)-ethanol hemisuccinate). This hapten was conjugated to BSA to prepare the immunogen. The effects of different types of solid phases on the equilibrium reaction between the hapten on solid phase and the polyclonal antiserum were evaluated to obtain a fine tuning of the antiserum performances in terms of specificity for p,p′-DDT and sensitivity to low levels of this pesticide. The calibration curves obtained show that it is possible to set up a sensitive assay for p,p′-DDT, employing a p,p′-dichlorodiphenylacetic acid-based solid phase, with a detection limit of 0.12 ng/mL and a working range of about 0.21–40 ng/mL. Selectivity towards several p,p′-DDT-related substances was good (o,p-DDT 17%, p,p′-DDD 1.2% o,p-DDD 6.3%, p,p′-DDE 6.7%).     

Excess enthalpies of aqueous ternary solutions of urea and polyols at 25°C

The heats of dilution of nine ternary solutions of urea and polyols have been determined at 25°C. Excess enthalpies and their virial coefficients h _xy have been evaluated and compared with the data reported in the literature for mono- and polyfunctional alcohols and other oxygenated nonelectrolytes. The group additivity approach of Savage and Wood was applied and the contributions to the enthalpy coefficients, due to the water mediated interactions between urea and the functional groups –CH₂–, –OH, and –O– were determined. On the other hand, by using empirical combination rules among the cross- and self-enthalpic interaction coefficients it is possible to emphasize the large differences in the behavior (even in the presence of urea) of the polyols (and in particular of cyclitols) and of saccharides.     

Phase diagram of softly repulsive systems: the Gaussian and inverse-power-law potentials

We redraw, using state-of-the-art methods for free-energy calculations, the phase diagrams of two reference models for the liquid state: the Gaussian and inverse-power-law repulsive potentials. Notwithstanding the different behaviors of the two potentials for vanishing interparticle distances, their thermodynamic properties are similar in a range of densities and temperatures, being ruled by the competition between the body-centered-cubic (bcc) and face-centered-cubic (fcc) crystalline structures and the fluid phase. We confirm the existence of a reentrant bcc phase in the phase diagram of the Gaussian-core model, just above the triple point. We also trace the bcc-fcc coexistence line of the inverse-power-law model as a function of the power exponent n and relate the common features in the phase diagrams of such systems to the softness degree of the interaction.     

Absolute configuration and conformational stability of (+)-2,5-dimethylthiolane and (-)-2,5-dimethylsulfolane

Enantiopure (+)-2,5-dimethylthiolane and (-)-2,5-dimethylsulfolane were prepared using literature procedures and investigated using vibrational circular dichroism (VCD). Experimental absorption and VCD spectra of (+)-2,5-dimethylthiolane and (-)-2,5-dimethylsulfolane in CCl(4) solution in the 2000-900 cm(-)(1) region were compared with the ab initio predictions of absorption and VCD spectra obtained with density functional theory using the B3LYP/6-311G(2d, 2p) basis set for different conformers of (2R,5R)-2,5-dimethylthiolane and (2R,5R)-2,5-dimethylsulfolane. This comparison indicates that (+)-2,5-dimethylthiolane is of the (2R,5R)-configuration and has two predominant conformations in CCl(4) solution. In addition, (-)-2,5-dimethylsulfolane is of (2R,5R)-configuration and has only one predominant conformation. The stereochemical assignment is in agreement with literature.