Self-Learning Compensation of Hysteretic and Creep Nonlinearities in Piezoelectric Actuators

Abstract: Solid-state actuators based on active materials allow high operating frequencies with nearly unlimited displacement resolution. This predestines them, for example, for application in highly precise positioning systems. However, the nonlinear behaviour in such systems is mainly attributed to actuator transfer characteristics as a result of driving with high amplitudes. In this paper a novel self-learning compensation method based on the socalled modified Prandtl-Ishlinskii approach is presented, which allows extensive compensation of the complex solid-state actuator hysteretic and creep nonlinearities during operation. Finally, it is shown in an example involving a two-axis piezoelectric parallel-kinematic positioning system that this compensation substantially decreases the deviations of the actual output displacements from the desired displacements of the controlled system

Heart ventricular activation in VAT difference maps from children with chronic kidney disease

Children with chronic kidney disease (CKD) are affected by cardiovascular complications, including disturbances in the intraventricular conduction system. Body surface potential mapping (BSPM) is a non-invasive method of assessing the cardioelectrical field. Our aim was to investigate conduction disturbances in young CKD patients using ventricular activation time (VAT) maps. Our study comprised 22 CKD children (mean age: 13.1 ± 2.5 years) treated conservatively and 29 control patients. For each child 12-lead electrocardiogram (ECG) readings were taken, and blood pressure and serum concentrations of iPTH, Pi, t-Ca, creatinine, Fe+3, ferritin, and Hb, as well as eGFR were measured. All children underwent registration in the 87-lead BSPM system, and group-mean VAT maps and a difference map, which presents statistically significant differences between the groups, were created. The VAT map distribution in CKD patients revealed abnormalities specific to left anterior fascicle block. The difference map displays the areas of intergroup VAT changes, which are of discriminative value in detecting intraventricular conduction disturbances. Intraventricular conduction impairments in the left bundle branch may occur in children with CKD. BSPM enables conduction disturbances in CKD children to be detected earlier than using 12-lead ECG. The difference map derived from the group-mean isochrone maps precisely localizes the sites of disturbed conduction in the heart intraventricular conduction system

Conduit artery structure and function in lowlanders and native highlanders: relationships with oxidative stress and role of sympathoexcitation

Research detailing the normal vascular adaptions to high altitude is minimal and often confounded by pathology (e.g. chronic mountain sickness) and methodological issues. We examined vascular function and structure in: (1) healthy lowlanders during acute hypoxia and prolonged ( 2 weeks) exposure to high altitude, and (2) high-altitude natives at 5050 m (highlanders). In 12 healthy lowlanders (aged 32 ± 7 years) and 12 highlanders(Sherpa; 33 ± 14 years) we assessed brachial endothelium-dependent flow-mediated dilatation(FMD), endothelium-independent dilatation (via glyceryl trinitrate; GTN), common carotid intima–media thickness (CIMT) and diameter (ultrasound), and arterial stiffness via pulse wave velocity (PWV; applanation tonometry). Cephalic venous biomarkers of free radical-mediated lipid peroxidation (lipid hydroperoxides, LOOH), nitrite (NO2 –) and lipid soluble antioxidants were also obtained at rest. In lowlanders, measurements were performed at sea level (334 m) and between days 3–4 (acute high altitude) and 12–14 (chronic high altitude) following arrival to 5050 m. Highlanders were assessed once at 5050 m. Compared with sea level, acute high altitude reduced lowlanders’ FMD (7.9 ± 0.4 vs. 6.8 ± 0.4%; P = 0.004) and GTN-induced dilatation (16.6 ± 0.9 vs. 14.5 ± 0.8%; P = 0.006), and raised central PWV (6.0 ± 0.2 vs. 6.6 ± 0.3 m s−1; P = 0.001). These changes persisted at days 12–14, and after allometricallyscaling FMD to adjust for altered baseline diameter. Compared to lowlanders at sea level and high altitude, highlanders had a lower carotid wall:lumen ratio ( 19%, P 0.04), attributable to a narrower CIMT and wider lumen. Although both LOOH and NO2 – increased with high altitude in lowlanders, only LOOH correlated with the reduction in GTN-induced dilatation evident during acute (n = 11, r=−0.53) and chronic (n = 7, r=−0.69; P 0.01) exposure to 5050 m. In a follow-up, placebo-controlled experiment (n=11 healthy lowlanders) conducted in a normobaric hypoxic chamber (inspiredO2 fraction (FIO2 )=0.11; 6 h), a sustained reduction in FMD was evident within 1 h of hypoxic exposure when compared to normoxic baseline (5.7±1.6 vs. 8.0 ±1.3%; P < 0.01); this decline in FMD was largely reversed following α1-adrenoreceptor blockade. In conclusion, high-altitude exposure in lowlanders caused persistent impairment in vascular function, which was mediated partially via oxidative stress and sympathoexcitation. Although a lifetime of high-altitude exposure neither intensifies nor attenuates the impairments seen with short-term exposure, chronic high-altitude exposure appears to be associated with arterial remodelling

New generation chemical agents for separating emulgated oil-water systems

W większości przypadków ilość wody produkowanej przez złoża roponośne w trakcie produkcji ropy rośnie z czasem. Wyprodukowana woda zwiększa koszt przetwarzania i przyczynia się do korozji rur. Problem występowania emulsji wodno-ropnej można rozwiązać za pomocą metod fizycznych lub chemicznych. W artykule przedstawiono wyniki badań przeprowadzonych na wybranych związkach chemicznych mających dobre właściwości do niszczenia wodno-ropnych emulsji. Uzyskane wyniki można zastosować w praktyce przemysłowejIn the course of oil exploitation, the quantity of reservoir water in its composition increases. Water results in the corrosion of pipelines, increases the exploitation and oil processing costs. From oils, which tend to form emulsions, water is removed by means of more or less sophisticated physical and chemical methods. The results of laboratory experiments on new generation chemical agents, having a high destabilization level of water-oil systems, are presented in the paper. The presented laboratory results can be used for technological processes applicable in exploitation industr

Analysis of properties of crude oil from the LMG field

Złoże ropy naftowej Lubiatów-Międzychód-Grotów (LMG) jest zróżnicowane geologicznie. Próbki płynów złożowych w poszczególnych partiach złoża posiadają specyficzne właściwości. W celu zapewnienia płynnego prowadzenia wydobycia należy dobrze poznać skład i właściwości gazu ziemnego i ropy naftowej. Szczególną uwagę należy zwrócić na zagrożenia związane z wytrącaniem się hydratów, parafin, asfaltenów i soli. W niniejszym artykule przedstawiono wyniki badań płynów złożowych z wybranych odwiertów złoża LMG. Analiza tych badań wskazuje na kierunki, jakie należy uwzględnić, projektując rozwiązania technologiczne.Oil field Lubiatów-Międzychód-Grotów (LMG) is diversified geologically. Samples of each part of the oil field deposits possess peculiar properties. Smooth exploitation can be carried on only when the composition and properties of the natural gas and the crude oil well are known. Special attention should be paid to threats connected with precipitating hydrates, paraffins, asphaltenes and salt. The results of analyses of oil field LMG are presented in the paper. The analysis of these results points out to the trends to be taken into consideration when designing technological solutions

Evaluation of salt precipitation from crude oil on the example of selected Polish mines

W artykule przedstawiono mechanizmy wydzielania się soli w wielofazowych układach charakterystycznych dla płynów złożowych. Następnie opisano zasady separacji płynów złożowych podczas wydobycia ropy naftowej. Szczególną uwagę zwrócono na rozdzielanie wysokozmineralizowanych solanek od ropy naftowej. Przeanalizowano składy wód złożowych na wybranych krajowych kopalniach ze względu na zawartości soli. Określono zawartości chlorków w ropach surowych po pierwszym stopniu separacji oraz możliwości wydzielania się soli w urządzeniach wydobywczych. Wskazano na sposoby likwidacji emulsji i odsalania ropy naftowej oraz przeciwdziałania wydzielania się dużych aglomeracji solnych.The mechanisms of precipitation in polyphase characteristic arrangements the salt for were introduced brine in article. The principle of separation of brine was described during exploitation of crude oil. Special attention was paid to distributing highly mineralized brines from oil. The compositions of brines were analyzed on the example of selected Polish mines with regard to salt content. The chlorides content was qualified for crude oils after the first degree of separation, and the possibility of precipitation in mining devices the salt was verified. The ways of liquidation of emulsion and salt removal from the crude oil were indicated and the measures against precipitation of large saline agglomerations

Demulsifiers and their influence on oil exploitation processes

Znacząca ilość wydobywanej ropy naftowej stanowi emulsję, która według światowych statystyk wynosi 25-35% wydobywanej ropy. Obecność emulsji zmniejsza wydobycie ropy naftowej z odwiertu i powoduje wzrost nakładów dla jej rozdzielenia oraz przyśpiesza korozję urządzeń eksploatacyjnych. Istnieje wiele metod rozdzielania emulsji ropnych, jednak większość z nich oparta jest na wspomaganiu związkami powierzchniowo czynnymi (ZPCz) zwanych demulgatorami. Dany ZPCz jest skuteczny tylko wobec badanej emulsji i bez wstępnych badań nie może być stosowany do rozdziału innych emulsji, gdyż może on powodować stabilizację bądź powstawanie emulsji wielokrotnych, która jest trudniejsza do rozdziału. Demulgator powinien być dobrany tak, aby nie powodował korozji aparatury, winien być nieszkodliwy i łatwy do usunięcia z wód ściekowych. Wymienioną problematykę omówiono w niniejszym artykule.A considerable part of exploited oil is emulsion, which according to the World's statistics constitutes 25-35% of extracted oil. The presence of emulsion decreases oil production from wells, resulting in the increase of cost of its separation and acceleration of corrosion of production utilities. A number of methods of oil emulsion separation exist; however majority of them are based on the surfactants (demulsifiers). A specific surfactant may be efficient only for a given emulsion. It cannot be used for other emulsion without prior studies and analyses as may result in stabilization or formation of hardly separable multiple emulsions. The demulsifier should be so selected as not to cause corrosion of utilities. It should also be non-toxic and easily removable from sewage water. These issues are discussed in the paper

Reply to Frewer et al. Comments on Janocha et al. Lie Symmetry Analysis of the Hopf Functional-Differential Equation. Symmetry 2015, 7, 1536-1566

We reply to the comment by Frewer and Khujadze regarding our contribution “Lie Symmetry Analysis of the Hopf Functional-Differential Equation” (Symmetry 2015, 7(3), 1536). The method developed by the present authors considered the Lie group analysis of the Hopf equations with functional derivatives in the equation, not the integro-differential equations in general. It was based on previous contributions (Oberlack and Wacławczyk, Arch. Mech. 2006, 58; Wacławczyk and Oberlack, J. Math. Phys. 2013, 54). In fact, three of the symmetries calculated in (Symmetry 2015, 7(3), 1536) break due to internal consistency constrains and conditions imposed on test functions, the same concerns the corresponding symmetries derived by Frewer and Khujadze and another, spurious symmetry, which was not discussed by Frewer and Khujadze. As a result, the same set of symmetries is obtained with both approaches