FREE INTERACTOR MATRIX METHOD FOR CONTROL PERFORMANCE ASSESSMENT OF MULTI-VARIATE SYSTEMS

In this paper, an alternative method for the assessment of multi-vitiate control loop performance with consider twocircumstances. First, known time delays between each pair of inputs and outputs, and second, without relying on any a priori knowledge about the process model or timedelays. The performance of the control loop is calculated from data driven autoregressive moving average (ARMA) and prediction error model. It is clear that the limited data in scalar measure used for performance assessment results tends to steady-state as time tends to infinity, but large number of samples gives risen in scalar measures and tends to infinity as time samples tends to infinity and therefore it becomes difficult to calculate the performance index. In this paper, the later problem is solved by considering initial part of scalar measures with steady value for next-to-next time samples to calculate the control-loop performance index which would be utilized to decide healthy working of the control loop. Simulation example is included to show the performance index of multi-variate control loop

On the Selection of Tuning Methodology of FOPID Controllers for the Control of Higher Order Processes

In this paper, a comparative study is done on the time and frequency domain tuning strategies for fractional order (FO) PID controllers to handle higher order processes. A new fractional order template for reduced parameter modeling of stable minimum/non-minimum phase higher order processes is introduced and its advantage in frequency domain tuning of FOPID controllers is also presented. The time domain optimal tuning of FOPID controllers have also been carried out to handle these higher order processes by performing optimization with various integral performance indices. The paper highlights on the practical control system implementation issues like flexibility of online autotuning, reduced control signal and actuator size, capability of measurement noise filtration, load disturbance suppression, robustness against parameter uncertainties etc. in light of the above tuning methodologies.Comment: 27 pages, 10 figure

Sustainable Fertilization in Medicinal and Aromatic Plants

The nutrient level in the soil is one of the most investigated aspects of agricultural research, also including research into Medicinal and Aromatic plants. The effect of fertilization has been studied in detail for many species, with contrasting results as concerns above all the qualitative aspects of production. Generally speaking, an increased level of nutrients induces an enhancement of plant biomass, but when the goal of cultivation is different from herbage yield, i.e. when a special plant part (seeds, or roots, or flowers) is of interest, or when the quality features are especially important, the outcome of fertilization may be dramatically different. A fine-tuned fertilization practice is therefore necessary, and forms, rates and times of distribution of fertilizers must be accurately planned and managed

The scent of Mare Nostrum: medicinal and aromatic plants in Mediterranean soils

In the Mediterranean area, the simultaneous occurrence of pedological, climatic and economic constraints often sets a limit on the profitability of agriculture, and farmers are forced to grow a reduced number of species, dealing with a secure – albeit low – market income. The introduction of medicinal and aromatic plants (MAPs) inside the current farming systems could represent a useful means to meet the multifunctional role of agriculture: producing safe food, in respect of the environment, and contributing to the development of rural areas. The study of the relationships between MAPs and the soils in which they may be grown may have two approaches: (1) the evaluation of yield and qualitative response of MAPs to the variation of soil features; and (2) the study of selective recovery of certain elements (toxic and beneficial), and their subsequent release in herbal products. In many MAPs, significant variations of plant characteristics have been ascertained with varying soil traits, and the selective recovery and subsequent release in food of certain elements have been demonstrated. Hence, great attention must be paid to the choice of soil and cropping strategies, to obtain satisfactory yields of high quality and best-priced products, respecting their safety and nutritional value