On constrained infinite-time linear quadratic optimal control with stochastic disturbances

In this work, we study the infinite-time linear quadratic optimal control problem for systems with stochastic disturbances and constrained inputs. A number of stochastic problem formulations under the full state information (FSI) structure are considered with a particular focus on the subject of feedback structure and its impact on certainty equivalence. In particular, we clarify results concerning the open-loop hard constrained, closed-loop statistically constrained, and closed-loop hard constrained cases. Extension to the infinite-time framework provides a vehicle for interpreting these controllers and indicates that the last of the three is of most interest to regulation type applications. Additionally, the partial state information problem is considered, and conditions are given for which a separated configuration consisting of the optimal estimator cascaded with the FSI optimal controller remains optimal.     

How to Evaluate and Forecast Changes in Landscape Image: The Case of a Small River Valley in Poland

River valleys play a key role in functioning landscape systems on a regional and continental level. Their ecological and cultural functions have developed simultaneously for centuries, creating a unique composition. Cultural heritage has grown from natural heritage and has enriched it wonderfully. However, river valleys have become areas of particularly intense human pressure for approximately the last two centuries, but especially over the last half century; changes occurring in the landscape are more and more drastic. The analysis and evaluation of these changes can therefore be a good indicator and predictor of changes that occur in the environment of entire (regional and transregional) landscape systems. This paper presents the method and results of landscape studies based on the sequence: retrospection—diagnosis—variant prognosis. The aim of the present work was to attempt to answer questions concerning the future direction of the development landscape physiognomy of small river valleys.     

Novel Magnetic Cobalt Cyanoferrate Nanoparticles as Potential Sorbent for Solid-Phase Extraction of Radionuclides from Aqueous Samples

A composite material based on magnetite and K₂[CoFe(CN)₆] was prepared. Structural and morphological studies of the sorbent were carried out, and the specific surface area was determined. The crystal structure of the material was studied by X-ray diffraction, and the composition was evaluated by energy-dispersive X-ray spectroscopy. Sorption of radionuclides was studied in batch experiments in relation to pH of the solution, mass of the adsorbent, and contact time. The adsorption kinetics was examined, the adsorption isotherm was constructed, and the adsorption capacity was determined. The resistance of the material to radiation to a dose of 250 kGy was evaluated. The material efficiently removes Cs and Am radionuclides from aqueous solutions. The sorbent seems to be sufficiently stable for practical use in the treatment of radioactive waste.     

Electrochemical and spectroscopic characterization of poly(1,8-diaminocarbazole): Part II. Electrochemical, in situ vis/NIR and Raman studies of redox reaction of PDACz in protic and aprotic media

Electrochemical redox reactions of poly(1,8-diaminocarbazole) (PDACz) films in aqueous (0.1 M HClO₄) and nonaqueous (0.1 M LiClO₄ in acetonitrile) solutions were studied by cyclic voltammetry, in situ vis/NIR and Raman spectroscopy. It has been demonstrated that spectroelectrochemical behavior of the polymer is strongly dependent on the nature of the solution used for doping-undoping but not on the medium used for electropolymerization. A redox couples Fe²⁺/Fe³⁺, Fe(CN)₆^4−/3− and tertrathiafulvalene were used as the probes for the studies of electroactivity of the oxidized polymer films. The results were discussed in terms of different mechanism of deprotonation process of the polymer in aqueous solution of 0.1 M HClO₄ and in 0.1 M LiClO₄ solution in aprotic acetonitrile and the reaction schemes in the two media are proposed.     

Increased Serum Level of Cyclopropaneoctanoic Acid 2-Hexyl in Patients with Hypertriglyceridemia-Related Disorders

We recently reported the presence of various cyclopropane fatty acids—among them, cyclopropaneoctanoic acid 2‐hexyl—in the adipose tissue of obese women. The aim of this study was to verify whether the presence of cyclopropaneoctanoic acid 2‐hexyl in human serum was associated with obesity or chronic kidney disease (both being related to dyslipidemia), and to find potential associations between the serum level of this compound and specific markers of the these conditions. The serum concentration of cyclopropaneoctanoic acid 2‐hexyl was determined by gas chromatography–mass spectrometry (GC–MS) in non‐obese controls, obese patients, obese patients after a 3‐month low‐calorie diet, and individuals with chronic kidney disease. Obese patients and those with chronic kidney disease presented with higher serum levels of cyclopropaneoctanoic acid 2‐hexyl than controls. Switching obese individuals to a low‐calorie (low‐lipid) diet resulted in a reduction in this fatty acid concentration to the level observed in controls. Cyclopropaneoctanoic acid 2‐hexyl was also found in foods derived from animal fat. Serum concentrations of triacylglycerols in the analyzed groups followed a pattern similar to that for serum cyclopropaneoctanoic acid 2‐hexyl, and these variables were positively correlated with each other among the studied groups. Patients with hypertriglyceridemia‐related conditions presented with elevated serum levels of cyclopropaneoctanoic acid 2‐hexyl. Our findings suggest that its high serum level is related to high serum triacylglycerol concentrations rather than to body mass or BMI.     

Modeling of thermally induced damage in the processing of Cr–Al2O3 composites

Thermal stresses induced during the cooling of Cr–Al₂O₃ (MMC) processed by sintering are modeled numerically using the FEA. The composite microstructure is modeled as (i) random distribution of ceramic particles (voxels) in the metal matrix, and (ii) using micro-CT scans of the real microstructure transformed into a FE mesh. Numerical simulations of the thermal residual stresses are compared with the test data measured by X-ray diffraction. A simple numerical model is then proposed to predict the overall elastic properties of the composite with account of the porosity and damage induced by the thermal stresses. Comparison of the model predictions with the measured data for Young’s modulus is presented.     

Electronic Nose as a Tool for Monitoring the Authenticity of Food. A Review

Counterfeiting of food is recently one of the risks relevant for producers, distributors, retailers, consumers, and national governments from economic (price), health (allergens), and religious reasons. Flavour of several food products is one of the key attributes of their quality and authenticity. In the case of some foods, the aroma of a product is specific enough to discriminate an original product from its fraud or adulterated counterpart. Electronic nose (e-nose) is a rapid and powerful technique, which requires no special sample preparation to determine the aroma of a product. In the present review, the applications of different e-noses and chemometrics for determination of food authenticity including adulteration and confirmation of origin are discussed. E-noses of various configurations are a very promising tool for testing the authenticity of food products.     

Temporal dependent neuroprotection with propentofylline (HWA 285) in a temporary focal ischemia model

The ergoline derivative, LEK-8829 (9,10-didehydro-N-methyl-(2-propynyl)-6-methyl-8-aminomethylerg oline), has been proposed as a potential atypical antipsychotic drug with antagonistic actions at dopamine D2 and serotonin 5-HT2 and 5-HT1A receptors (Krisch et al., 1994, 1996). LEK-8829 also induces contralateral turning in rats with 6-hydroxydopamine-induced unilateral lesion of dopamine nigrostriatal neurons. Turning is blocked by SCH-23390 (R(+)-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzaze pine), a dopamine D1 receptor antagonist. It has been suggested that LEK-8829 could have beneficial effects in parkinsonian patients suffering from psychotic episodes induced as a side-effect of antiparkinsonian treatment with dopamine D2 receptor agonists. Therefore, we now investigated the interaction of LEK-8829 with the dopamine D2 receptor agonist bromocriptine (2-bromo-alpha-ergokryptine) in 6-hydroxydopamine-lesioned rats. Treatment with either LEK-8829 (3 mg kg(-1)) or bromocriptine (3 mg kg(-1)) induced a vigorous contralateral turning response. The cumulated number of turns induced by the treatment with both drugs combined was not significantly different from the cumulated number of turns induced by single-drug treatment. The pretreatment with SCH-23390 (1 mg kg(-1)) did not have a significant effect on the bromocriptine-induced turning but significantly decreased the turning observed after the combined LEK-8829/bromocriptine treatment. We conclude that in the 6-hydroxydopamine model, the turning behaviour mediated by the LEK-8829/bromocriptine combination may be the result of opposing activity of both drugs at dopamine D2 receptors with concomitant stimulation of dopamine D1 receptors by LEK-8829. Therefore, LEK-8829 may have a potential for the therapy of parkinsonism complicated by dopamine D2 receptor agonist drug-induced psychosis.