Discrete-Time System Conditional Optimization in the Parameter Space with Nonzero Initial Conditions

The paper presents a new approach to the design of the classical PD controller for the plant in the closed loop control system. Proposed controller has two unknown adjustable parameters which are designed by the algebraic method in the two dimensional parameter space, by using the newly discovered characteristic polynomial of the row nondegenerate full transfer function matrix. The system relative stability, in regard to the chosen damping coefficient is achieved. The optimality criterion is the minimal value of the performance index and sum of squared error is taken as an objective function. The output error used in the performance index is influenced by all actions on the system at the same time: by nonzero initial conditions and by nonzero inputs. In the classical approach the output error is influenced only by nonzero inputs. Experimental results confirm that by taking into account nonzero initial conditions, an optimal solution is obtained, which is not the case with the classical method where optimization is performed at zero initial conditions

Stacking interactions between chelate and phenyl rings in square-planar complexes of Cu, Ni, Pt and Pd

Previous analysis of geometrical parameters in the crystal structure of square-planar complexes, with and without chelate rings, of all transition metals from Cambridge Structural Database shows that there are stacking interactions between the phenyl ring and the chelate ring with delocalized -bonds. To investigate whether the type of metal atom influence this interaction we compare stacking parameters for the complexes with and without chelate rings in the complexes containing Cu(II), Ni(II), Pd(II) and Pt(II) metals. While the overall picture is similar for all four cases, complexes of Pd and Pt without chelate ring show tendency to form shorter contacts towards aromatic carbon. It was found that this behaviour is associated with the presence of cyano or isocyano derivatives as ligands.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Discrete-Time System Conditional Optimisation in the Parameter Space via the Full Transfer Function Matrix

Dynamic systems operate under the simultaneous influence of both the initial conditions and the input vector. There is neither physical nor mathematical justification for ignoring the initial conditions, e.g., in the control optimisation. This paper gives a response to the following question: Is a set of controller parameters which is optimal for the operation of a control system under zero initial conditions also optimal for its operation under non-zero initial conditions? The paper presents a new approach to the design of a classical proportional-difference-sum (PDS) controller for a plant in a closed loop control system. The system relative stability with respect to a desired damping coefficient is accomplished. The minimal value of the performance index in the form of the sum of squared errors is the optimality criterion. Unlike the classical approach, the output error used in the performance index is influenced by all actions performed on the system at the same time

Discrete-time system conditional optimisation in the parameter space via the full transfer function matrix

Dynamic systems operate under the simultaneous influence of both the initial conditions and the input vector. There is neither physical nor mathematical justification for ignoring the initial conditions, e.g., in the control optimisation. This paper gives a response to the following question: Is a set of controller parameters which is optimal for the operation of a control system under zero initial conditions also optimal for its operation under non-zero initial conditions? The paper presents a new approach to the design of a classical proportional-differencesum (PDS) controller for a plant in a closed loop control system. The system relative stability with respect to a desired damping coefficient is accomplished. The minimal value of the performance index in the form of the sum of squared errors is the optimality criterion. Unlike the classical approach, the output error used in the performance index is influenced by all actions performed on the system at the same time

Comparison of two views regarding the nature of the X-H…phenyl interaction

There are two approaches in the analysis of the nature of the X-H…phenyl interactions. One is based on the assumption that atoms, bonds and the π plane belonging to the phenyl ring, are the points which can be involved in the interaction. The other states that center of the phenyl ring is the point acceptor. In this paper we compare two views using the directionality of the X-H vector and length/angle correlations relative to both assumed point acceptors. The results suggest that on the basis of this methodology there is no clear answer regarding the nature of the acceptor site in the phenyl ring.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Conditional optimization of computer automatic control system of an selected plant at arbitrary initial conditions

The aim of this paper is to present effect of initial conditions on choice of optimal parameters in computer automatic control system of an selected actual plant. Considering is made in a parameter plane wherein the area of formerly guaranteed relative damping coefficient of all closed-loop poles is separated. A performance index is chosen to be sum of error squared (SSE), taking into account of arbitrary initial conditions. Experimental results obtained on coupled-tanks plant are provided

Colorectal anastomosis dehiscence following radical surgical operation for rectal carcinoma

Background/Aim. Colorectal cancer (CRC) is one of the biggest health problems of modern humanity, especially in highly developed countries. In Serbia about 3,200 patients suffer from CRC, out of whom about 1,100 patients suffer from rectal cancer (RC), while about 2,100 patients suffer from other colon segments cancer. The aim of the study was to show the incidence genesis of one of the possible early postoperative complications regarding dehiscence of the colorectal anastomosis (CRA) with a group of patients suffering from RC and operated by using sphincter-saving procedures, in the period from 1993 to 2007, and then to compare the incidence genesis of these complications with those in the published series of the reporting colorectal institutions. Methods. The research included 242 patients radically operated on for RC in a 15-year period using some of sphincter-saving procedures following by a careful analysis of the symptoms of subclinical dehyscencias not solved with the reintervention as well as of the clinically evidented dehyscencias mostly solved by reoperation. Results. With 22 (9.1%) patients in the first 10 postoperative days there were early postoperative symptoms of CRA dehiscence. In 6 (2.47%) of the patients there were subclinical signs of raised body temperature, less quantity of feces content, and after the conservative treatment they ended in spontaneous process of rehabilitation. In 16 (6.61%) patients there was clinically evidented anastomosis dehiscence followed by abundant drainage of feces content, signs of local peritonitis, pelvic sepsis, so we had to undertake surgical intervention. Conclusion. Comparing the results of a few tenths of published studies with our results we proved that performing and operative technique of colorectal anastomosis in the patients suffered and radically surgically treated for RC, is quite adequate with the operative technique in reporting world institutions that are engaged in surgical treatment of RC

Discrete-time system conditional optimization based on Takagi-Sugeno fuzzy model using the full transfer function

The study proposes a novel method for synthesis of a discrete-time parallel distributed compensation (PDC) controller for the nonlinear discrete-time Takagi–Sugeno (TS) fuzzy plant model. For each of the fuzzy plant model linear subsystems, a local linear first order proportional-sum (PS) controller is designed. The algebraic technique is used in two-dimensional parameter space, utilizing the characteristic polynomial of the row nondegenerate full transfer function matrix. Each system’s relative stability is accomplished in relation to the selected damping coefficient. The supplementary criterion is the minimal value of the performance index in the form of the sum of squared errors (SSE). However, unlike the traditional technique, output error is influenced by all simultaneous actions on the system: nonzero inputs and nonzero initial conditions. The full transfer function matrix of the system allows for the treatment of simultaneous actions of the input vector and unknown unpredictable initial conditions. In order to show the improvement caused by the application of a new optimization method that considers nonzero initial conditions, a comparison of PDC controllers designed under zero and nonzero initial conditions is given, where the system in both cases starts from the same nonzero initial conditions, which is often the case in practice. The simulation and experimental results on a DC servo motor are shown to demonstrate the suggested method efficiency

Influence of metal and ligand types on stacking interactions of phenyl rings with square-planar transition metal complexes

In order to find out whether metal type influences the stacking interactions of phenyl rings in square-planar complexes, geometrical parameters for Cu, Ni, Pd and Pt complexes, with and without chelate rings, were analyzed and compared. By searching the Cambridge Structural Database, 220 structures with Cu complexes, 211 with Ni complexes, 285 with Pd complexes, and 220 with Pt complexes were found. The results show that the chelate ring has a tendency to make the stacking interaction with the phenyl ring independent of metal type in the chelate ring. However, there are some differences among metals for complexes without a chelate ring. There are a number of structures containing Pd and Pt complexes, without chelate rings, that have short carbon-metal distances and parallel orientations of the phenyl ring with respect to the coordination plane. It was found that some of these complexes have a common fragment, CN, as a part of the ligands. This indicates that the CN supports stacking interactions of square planar complexes with the phenyl ring. (C) Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved

Thermodynamic and thermophysical properties for green compounds at high pressures

The harmful impact of the fossil fuels consumption on the environment and their limited reserves have prompted a reaction from both researchers and government officials. New environmental protection measures have been adopted and the research for renewable energy sources is strongly supported. The goal is to find the renewable, non-toxic, biodegradable, environment-friendly substitutes for fossil fuels and optimize their use. Within our research various green solvents and biofuels, such as biodiesels, terpenes, ionic liquids, and deep eutectic solvents have been studied. Biodiesels are widely known substitutes for fossil fuels; they can be applied in diesel engines, pure or mixed with a petro-diesel in various proportions, without corrections in engine design [1]. Terpenes found a promising role as an alternative fuel for aviation transport where fuel of high energy density is required due to small volume-limited fuel tanks [2]. Ionic liquids have shown a great potential in CO2 absorption from air or exhaust gas. These salts are very attractive for industrial purposes, because of their specific properties, changed based on selected combination of anion and cation [3]. Further, for more efficient energy production and consumption, investigation on improving the properties of the heat transfer fluid was performed, adding nanoparticles to ethylene glycol (EG) [4]. The data on thermophysical properties of various chemical compounds and their mixtures under different conditions of pressure and temperature are essential for various processes. For example, the fuel injection and combustion in diesel engines are performed at high pressures and temperatures and are greatly influenced by the fuel’s density and viscosity [1]. Densities of sunflower oil biodiesels and their mixtures with diesel fuel, a group of terpenes and ionic liquids, and EG with caffeine were measured at temperatures in the range (298.15–413.15) K and at pressures up to 60 MPa [1-4]. The experimental data were successfully correlated using the modified Tammann–Tait equation. That enabled the calculation of the derived properties, such as the isothermal compressibility, the isobaric thermal expansivity, the internal pressure and the difference between the specific heat capacity at constant pressure and at constant volume