Oleuropein protects low density lipoprotein from oxidation

The Mediterranean diet, rich in fruit, vegetables, grain, and vegetable oil (mainly olive oil) is correlated with a lower incidence of coronary heart disease (CHD). Natural antioxidants contained in the Mediterranean diet might also play a role in the prevention of cardiovascular diseases, through inhibition of LDL oxidation. We tested this hypothesis "in vitro" by inducing LDL oxidation with copper sulphate and preincubating the samples with oleuropein, the bitter principle of olives, that is one of the major components of the polyphenolic fraction of olive oil. Oleuropein 10(-5) M effectively inhibited CuSO4-induced LDL oxidation, as assessed by various parameters. We demonstrate in this investigation that polyphenolic components of the Mediterranean diet interfere with biochemical events that are implicated in atherogenetic disease, thus proposing a new link between the Mediterranean diet and prevention of CHD.     

PID autotuning for weighted servo/regulation control operation

This paper analyzes optimal controller settings for controllers with One-Degree-of-Freedom (1-DoF) Proportional-Integral-Derivative (PID) structure. A new analysis is conducted from the point of view of the operating mode (either servo or regulation mode) of the control-loop and tuning mode of the controller. Performance of the optimal tuning settings can be degraded when the operating mode is different from that selected for tuning and obviously both situations can be present in any control system. In this context, a Weighted Performance Degradation index, that considers the importance and balance between the servo and regulation operation modes, is minimized and based on this minimization, an autotuning procedure as a function of the normalized process dead-time is proposed.     

The role of antioxidants in the mediterranean diet

Traditional Mediterranean diets, as opposed to North European and American diets, include a significantly large amount of plant foods; this notable difference between the two eating styles, despite the similarities among other classic risk factors for coronary heart disease (CHD) such as high plasma cholesterol levels, has been associated with a lower risk of developing the CHD and certain cancers. The involvement of excessive free radical production and the great number of epidemiologic studies linking antioxidant intake with a reduced incidence of the above-mentioned diseases indicate that dietary antioxidants likely play a protective role. Because diets in the Mediterranean are (or better yet, were) characterized by abundant plant foods (fruits, vegetables, breads, nuts, seeds; wine and olive oil), this article includes a review of the potential activities of dietary antioxidants, which are plentiful in Mediterranean diets, and wine as related to human disease.     

Constrained control strategies for disturbance rejection in a solar furnaces

This paper addresses the temperature control problem in a solar furnace. In particular, two control strategies for the disturbances rejection (represented by the variation of the input energy provided by the Sun, mainly because of passing clouds and the solar daily cycle) are proposed, based on a two-degrees-of-freedom scheme. The first one is based on generalized predictive control, where a nonlinear model is employed for free response prediction while a linearized model is used for the computation of the forced response. Amplitude and slew-rate constraints on both the control variable and the output of the system are taken into account. The second one is a constrained control strategy where both the process input and output constraints are taken into account explicitly. In both cases an adaptation of the most significant process parameter is performed. Simulation and experimental results show the effectiveness of the methodologies.¹     

Optimal inversion-based control for the set-point regulation ofnonminimum-phase uncertain scalar systems

We propose an optimal inversion-based control for the set-point constrained regulation of nonminimum-phase uncertain scalar systems. This approach is based on a new control architecture where the main purpose of the feedback is to reduce the sensitivity to parametric plant uncertainties permitting in such a way the effective use of a feedforward action determined via a stable dynamic inversion. Essential constituents of the architecture are a parameterized family of “transition” polynomials to shape ideal output transfers and a parameterized controller ensuring the internal model principle. The methodology is then centered on the optimal combined design of the feedback controller and of the inversion-based command signal in order to minimize the worst-case settling time subject to an amplitude constraint on the control variable and to arbitrarily assigned overshoot and undershoot bounds. Finally, an approximate or suboptimal solution to the resulting nonlinear optimization problem can be obtained by genetic algorithms. A worked example highlights the effectiveness of the overall methodology     

Characterization of limit cycles for self-regulating and integral processes with PI control and send-on-delta sampling

This work is focused on the study of limit cycles that appear in a control scheme which is based on the use of a PI controller with an event-based send-on-delta sampling (SOD). The processes investigated are integrator processes plus time delay (IPTD) and first and second order processes plus time delay, which are of interest because they are frequently used to model many industrial processes. The SOD sampling is characterized as a non-linearity of n levels with hysteresis. An algorithm to calculate the limit cycles properties is proposed, and then the results obtained in simulations are compared with experiments performed on a real plant, a distributed solar collector field at the Solar Platform of Almería (PSA, Spain).     

Identification and Tuning Methods for PI Control Systems Based on Symmetric Send-on-delta Sampling

International Journal of Control, Automation and Systems - Two procedures for the definition of an autotuning algorithm for event-based proportional-integral (PI) control systems are proposed in...