Spectral and statistical analysis for ferroresonance phenomenon in electric power systems

This study presents our findings on the ferroresonance phenomenon for the Seyitomer?CIsiklar part of the Electric Power System of 380?kV in Turkey. In this context, the power spectral density approach and Short-Time Fourier Transforms are applied to the voltage variations for phase R of the sample power network. The findings show that the ferroresonance event can be represented by the interharmonics between 50 and 250?Hz, as well as statistical properties. In addition, a histogram of the ferroresonance region shows a different characteristic from the overall data and the non-ferroresonance region. This different characteristic can be defined by an asymmetrical distribution characteristic, and its numerical measure is given by the ??Noise to Signal Ratio?? of 0.624.     

Main quality attributes and antioxidants in Hungarian sour cherries: identification of genotypes with enhanced functional properties

Sour cherry (Prunus cerasus L.) cultivars native to Hungary and some of them grown worldwide, display great phenotypic variability. Eleven sour cherry cultivars were analysed for their main quality attributes including fruit weight, soluble solid content, acidity, pH, specific sugars (glucose and fructose), antioxidant capacity as well as total polyphenolic (TPC), total anthocyanin (TMAC) and vitamin C contents. Results showed wide variation in both fruit quality and antioxidant parameters of Hungarian sour cherries. The anthocyanin contents varied from 11.3 to 93.5 mg/100 g. An amarelle‐type cultivar, ‘Pipacs 1’ showed the highest antioxidant capacity (21.85 mmol AA L^?1), TPC (49.04 mg GA L^?1) and vitamin C (8.98 mg/100 g) content. Key enzymes in anthocyanin biosynthesis were expressed in both yellow‐coloured flesh and red skin of ‘Pipacs 1’ fruits at all ripening stages. The detected diversity presents a choice that can satisfy different consumer preferences, and meet specific nutritional requirements.     

Antioxidant and antiradical capacities in apricot (Prunus armeniaca L.) fruits: variations from genotypes, years, and analytical methods

The fruit quality parameters and antioxidant capacity (ferric reducing antioxidant power, FRAP) and total phenolic content (TPC) were determined in 27 apricot cultivars and hybrids of diverse origins. Twenty one- to 35-fold variations were measured among FRAP and TPC values. Besides genotype, harvest year also contributed significantly (P≤0.05) to the variations of TPC presumably due to the climatic differences between years. A subset of genotypes (15) was also analyzed for their antiradical activities (2,2'-diphenyl-1-picrylhydrazyl, DPPH; total radical-scavenging activity, TRSA; water-soluble antioxidant capacity, ACW; and lipid-soluble antioxidant capacity, ACL), and vitamin C contents as well as color indices (CIE H°, L*, and chroma). The hybrid "Preventa" had outstanding FRAP (>10.4 mmol ascorbic acid/L), DPPH (74.45%), TRSA (0.002%), ACW (33587.5 nmol AA/L) and ACL (78.65 nmol Trolox/L), TPC (>2890.0 mg gallic acid/L), and vitamin C (16.17 mg/100 g FW) levels and an average carotenoid content estimated from the hue angle (66.99°). Most antioxidant and antiradical activities correlated significantly except for TRSA; the closest correlation was observed between FRAP and ACW (r=0.952). Only TRSA showed significant correlations with color indices, H° and chroma, suggesting TRSA measures at least a fraction of the antioxidant capacity attributable to apricot carotenoids.     

Oxidative polymerization of N‐vinylcarbazole in polymer matrix

A new class of soluble conductive poly(N‐vinylcarbazole) (PVCz) compounds has been developed by oxidative matrix polymerization of N‐vinylcarbazole (NVCz) by Ce(IV) in the presence of poly(ethylene glycol) (PEG). PEG was found to be a more suitable matrix with which to obtain a stable homogenous ternary complex solution when compared with poly(acrylic acid) (PAA) and poly(vinylpyrrolidone) (PVP). The role of PEG, NVCz and Ce(IV) concentration, order of component addition, the structure of the polymer matrix, molecular weight of polymer and the effect of solvent have been investigated. Obtaining soluble PEG–Ce(III)–PVCz ternary complexes was shown by cyclic voltammetric measurements, and the initial rate of formation NVCz cation radicals as calculated using UV–visible spectrophotometry. Advantageously with these soluble complexes, conductivities could be measured both in solution and in the solid state. © 2001 Society of Chemical Industry     

Study about development of extracapillary blood flow type oxygenator--comparison with HF-4000, Capiox II, and Silox]

Results about comparison of new extracapillary blood flow type polypropylene hollow fiber oxygenator (PHO) with HF-4000, Capiox II and Silox for effects on blood components, hemolysis, immunoglobulin and high molecular weight proteins, such as complements: 1) Platelet protection was about equal. Silox was best in leucocyte protection. 2) PHO was superior to HF-4000. The extracapillary type was better for hemolysis. 3) Silox was best in immunoglobulin protection. Effect on C3 and C4 was equal, and Silox was best in protection of CH50. Slight differences were caused by silicone membrane, not caused by blood flow type. 4) PHO was superior to HF-4000 (commercial extracapillary type), and almost equal to Capiox II (intracapillary type).     

Electroiniated cationic polymerization in the presence of addition-fragmentation agents

Summary Electrochemical initiation of cationic polymerization of heterocyclic and vinyl monomers such as cyclohexene oxide (CHO) and butyl vinylether (BVE), respectively at low potentials in the presence of allylic salts namely, allyl-thiophenium (AT), allyl-triphenyl phosphonium (APP), allyl-isoquinolinium (AIQ), allyl-pyridinium (AP) and allyl-dimethyl anilinium salts, was investigated. The mechanism of this polymerization was studied using cyclic voltammetry and by electropolymerization experiments performed in undivided and H-type cells. A mechanism involving addition-fragmentation decomposition of allylic salts by free radical species formed by electrolysis of trace amounts of water present in the system is postulated. Received: 6 September 2002/Revised version: 18 November 2002/ Accepted: 18 November 2002 Correspondence to Yusuf Yagci     

Nanofiber network of electropolymerized 3,4-(2-benzylpropylenedioxy)thiophene on single carbon fiber microelectrode

Electropolymerization of 3,4-(2-benzylpropylene)-dioxythiophene (ProDOT-Bz) on (approximately 7 microm diameter) single carbon fiber microelectrodes (SCFMEs) in different electrolytes resulted the network of nanofiber structure. Electropolymerization performed in different electrolytes by using cyclovoltammetric technique. Surface morphology of coatings was investigated by Scanning Electron Microscopy (SEM), the attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used for the characterization. A linear relationship between peak currents of films with polymerization charge, and capacitances and coating thickness were obtained. The size of nanofiber network (and pores) can be controlled by the scan rate of the cyclovoltammetric process. Electrochemical impedance spectroscopic investigation of these nanostructures has been indicated the capacitive behavior of electrode system. Electrochemical Impedance Spectroscopic characterization (Capacitance) of the PProDOTBz/SCFME consisting cell was simulated at applied potential and parameters explained by equivalent circuit modeling.     

Effect of pulsatile and nonpulsatile assist on heart and kidney microcirculation with cardiogenic shock

To estimate microcirculation of the heart and kidney in pulsatile and nonpulsatile-assisted circulation, a comparison study was done using a swine model. Acute myocardial infarction was made by ligation of the left coronary artery branches. After cardiogenic shock, animals were divided into 3 groups as follows: Group C (n = 6), no assist provided; Group NP (n = 6), assisted by a nonpulsatile pump (Bio-Medicus BP-80); Group P (n = 6), supported by a pulsatile pump (Nippon Zeon). left coronary artery flow, endocardial and epicardial regional flows, and renal cortex and medulla tissue blood flows were measured. Left coronary artery flow and endocardial and epicardial tissue blood flows decreased in cardiogenic shock, and they recovered to the control level soon after support in both Group N and Group P. Renal medulla and cortex tissue blood flows decreased in cardiogenic shock, and these flows did not recover in either Group N or P. However, cortex blood flow in Group P did improve, but it did not improve in Group N. These results suggested that pulsatile assist was more effective than nonpulsatile assist for microcirculation after cardiogenic shock to avoid deterioration of major organ functions.     

Examples when nonlinear model predictive control is nonrobust

We consider nominal robustness of model predictive control for discrete-time nonlinear systems. We show, by examples, that when the optimization problem involves state constraints, or terminal constraints coupled with short optimization horizons, the asymptotic stability of the closed loop may have absolutely no robustness. That is to say, it is possible for arbitrarily small disturbances to keep the closed loop strictly inside the interior of the feasibility region of the optimization problem and, at the same time, far from the desired set point. This phenomenon does not occur when using model predictive control for linear systems with convex constraint sets. We emphasize that a necessary condition for the absence of nominal robustness in nonlinear model predictive control is that the value function and feedback law are discontinuous at some point(s) in the interior of the feasibility region.