Laser induced birefringence in La–Ga–S–O–Gd glass polymer nanocomposites

In this work, we demonstrate a possibility to use La–Ga–S–O–Gd glass polymer nanocomposites as effective materials for photo-induced birefringence. Here we chose PVA as a photopolymer matrix. The photo-induced effects were studied using 8 ns Nd: YAG laser generating bicolor coherent light beams with wavelengths 1064, and 532 nm. The detection of the photo-induced birefringence was carried out using cw He–Ne laser at 1150 nm. The optimal concentration of the nanoglass favoring maximal changes of refractive indices is established. The photo-induced laser power density was changed up to 0.9 GW/cm2. The photo-induced beams were incident at angles varying within the 32° and 52° with respect to the nanocomposite planes. The polarizations of the beams did not play principal role. We discovered an appearance of maximal birefringence equal to about 0.078. The effect is strongly dependent on the nanoparticle sizes and is completely reversible after switching off the laser treatment within several milliseconds. Such features are useful for the recording of optical information and production of gratings with desirable periods

Optimized sensorless control systems for cargo movement mechanisms

THE PURPOSE. Investigation of the control system of the cargo movement mechanism when using different variants of sensorless control. The search for the optimal option, in which the formation of the speed is identical to the data obtained from the speed sensor. Analysis of the results obtained during the study, including the results obtained taking into account the heating of the motor windings. METHODS. The tasks set during the research are implemented by simulation modeling using the Matlab Simulink computer simulation environment. RESULTS. The article considers systems with different types of velocity observers. A system is implemented that takes into account the heating of the stator and rotor windings of an asynchronous motor, in which a non-adaptive observer and different types of neural network controller were introduced. A combined method of using neural network regulators is proposed. CONCLUSION. Sensorless control systems are relevant for use in industries with the presence, according to the conditions of the technological process, of high temperatures. The conducted research has shown that the use of neural network technologies allows you to work with settings of different levels and types. The proposed method, implying the use of joint work of neural network observers with various neurostructures, allows for speed testing in the entire range. The connection with cloud storage present in the proposed structure leads to the unloading of the management system, allowing to increase the process of analyzing data coming from the object.publishe

Analiza cen energii elektrycznej na Towarowej Giełdzie Energii

The main part presents the analysis of prices for electricity at the polish power exchange. The structure of production, energy consumption, power generation structure and energy exchange with foreign countries is described and illustrated in the National Power Solution characteristics. The basic specific information about the national system such as installed capacity, achievable capacity, production and consumption of electric power in Poland is provided. Polish Power Exchange is characterized. Furthermore, the existing markets and their nature, forming of turnover and prices mainly on the Day Ahead Market are discussed. The application of the above in terms of management in the power sector and its benefits is outlined. The purpose of this study is to analyse the structure and situation of Polish Power Exchange and to examine functioning of the Day Ahead Market in Poland.Główna część artykułu przedstawia analizę cen energii elektrycznej na towarowej giełdzie energii. Strukturę produkcji, zużycie energii, strukturę wytwarzania energii i wymianę energii z zagranicą opisano i zilustrowano w charakterystyce narodowego rozwiązania energetycznego. Ponadto przedstawiono podstawowe informacje o krajowym systemie, takie jak zainstalowana moc, osiągalna moc, produkcja i zużycie energii elektrycznej w Polsce. Scharakteryzowano Towarową Giełdę Energii. Ponadto w artykule omówiono istniejące rynki i ich charakter, kształtowanie się obrotów i ceny, głównie na Rynku Dnia Następnego. Omówiono zastosowanie wyżej wymienionych w zakresie zarządzania w sektorze energetycznym i jego korzyści. Celem niniejszego opracowania jest analiza struktury i sytuacji Towarowej Giełdy Energii oraz zbadanie funkcjonowania Rynku Dnia Następnego w Polsce

Wpływ zarządzania czasem obciążenia elektrycznego na wymiarowanie i koszty hybrydowego odtwarzalnego systemu zasilania

This paper describes modelling, simulation and sizing of hybrid renewable system for pumping of soaking water from closed mine Bankov in Košice and different electrical power load time management strategies for using electricity. There will be analysed three different time management strategies of electrical load and how they affects to cost and sizing of hybrid renewable systems. Time management of load time in hybrid systems can affect sizing and cost in such system. Hybrid renewable systems are suitable in remote area where the connection to the grid is unprovable and building such connection to grid is very expensive and renewable sources are often only supplementary sources to diesel generators, but renewable sources as solar, wind has no costs on fuel and can cause reducing in costs of one kilowatt electric energy.W artykule opisano modelowanie, symulację i dostosowanie hybrydowego systemu odnawialnego dla pompowania wody z zamkniętej kopalni Bankov w Koszycach oraz różnych strategii zarządzania czasem obciążenia elektrycznego przy wykorzystaniu energii elektrycznej. Zostaną przeanalizowane trzy różne strategie zarządzania czasem w obwodzie elektrycznym i ich wpływ na koszty i rozmiary hybrydowych systemów odnawialnych. Zarządzanie czasem czasu ładowania w systemach hybrydowych może mieć wpływ na rozmiar i koszt w takim systemie. Hybrydowe systemy odnawialne mają zastosowanie w odległych obszarach, w których połączenie z siecią jest niedopuszczalne, a budowa takiego połączenia z siecią jest bardzo kosztowna. Odnawialne źródła są często tylko źródłami uzupełniającymi dla generatorów diesel’a, jednak odnawialne źródła takie jak energia słoneczna, energia wiatrowa nie mają kosztów paliwa i mogą powodować zmniejszenie kosztów jednej kilowatowej energii elektrycznej

Estimation of total, direct and diffuse PAR under clear skies in complex alpine terrain of the National Park Berchtesgaden, Germany

Information about total, direct and diffuse photosynthetically active radiation (PAR) is required in simulation models to estimate carbon gain and growth of vegetation. While there are existing worldwide networks of stations where direct, diffuse and reflected global radiation are measured using standardized methodology, no such network exists for PAR. In complex mountainous terrain, few published studies have examined even global radiation distribution as influenced by topography. We have developed a model to estimate the total, direct and diffuse photosynthetically active radiation in complex terrain. The model includes: (1) a parametric atmospheric model to extrapolate atmospheric conditions to any given location in complex terrain (which directly determines the potential PAR radiation that can be received on a horizontal surface) and (2) a topographic model, which accounts for the alteration of PAR radiation caused by terrain. Validation of the model was undertaken first for a baseline valley site at Schönau, an essentially flat surface with simple surrounding terrain. The hourly step atmospheric conditions were fit using direct PAR measurements at Schönau, and then applied in the parametric model to simulate the total and diffuse PAR. The results demonstrate that the parametric model provides good and fairly good simulations for total and diffuse PAR, respectively. In a second step, the model was tested for total PAR at five sites with distinctive topographic characteristics in the National Park Berchtesgaden, Germany, and for direct and diffuse radiation at two of the five sites with direct and diffuse PAR measurements. The model simulated total PAR well with high R2 (all >0.90). The NRMSE varies from 8% to 26% depending on sites. Although high R2 were found for direct PAR at the two sites Kederbichl and Bartholomä (both 0.92), lower R2 of 0.64 and 0.65 were obtained for the diffuse PAR simulation. While the NRMSE for diffuse PAR was also lower (0.23 for Kederbichl site and 0.26 for Bartholomä site), this difference was not as pronounced (0.31 for Kederbichl site and 0.28 for Bartholomä site for direct PAR). The R2 decreases to 0.14 and 0.33 for the two sites in the diffuse PAR simulation, if the diffuse PAR is treated isotropically. Thus, the results suggest that consideration of anisotropic distribution of diffuse radiation is required in PAR extrapolation models within complex alpine terrain

The Investigation on the E-J Characteristics and the Role of Nanoparticle Concentration in Weakly Polar Magnetic Fluids

The paper presents investigation on the magnetic fluids that are stable colloidal suspensions of single-domain magnetic particles in a liquid carrier of dielectrics nature. Studies were made on the electric field vs. current density, e.i. E-J characterization commonly observed in insulating liquids under uniform low electric or magnetic fields. High performance oil was used as the dielectric carrier. The experiments were carried out at different volume concentrations of magnetite nanoparticles up to 4%

Generation of Fe₃O₄ Nanoparticle Aggregates in a Ferrofluid Driven by External Electric Field

In the paper the experimental study of magnetic nanoparticle aggregation in a transformer oil based ferrofluid driven by an external electric field is reported. The studied ferrofluid was composed of the magnetite nanoparticles, oleic acid surfactant, and transformer oil. Generally, it is considered that superparamagnetic nanoparticles do not interact in the absence of external magnetic field. In the paper we present an experimental observation of the particle assembly formation in a direct current external electric field by optical microscopy. During the observation no external magnetic field was applied. A diluted low-polarity ferrofluid drop on a glass surface was exposed to the external static inhomogeneous electric field. It is assumed that induced dipole-dipole interaction and subsequent dielectrophoretic motion give rise to the electrohydrodynamic flow in the fluid after a certain time period. As a result, a visible particle chain was formed at the drop electrical equator. This demonstration is expected to contribute to the understanding of the streamer formation and electrical breakdown in transformer oil based ferrofluids

Frontal Sinus Osteoma Presenting with Meningitis and Epilepsy

Osteomas are benign lesions of bone, most frequently seen in the paranasal sinuses; however, they are typically asymptomatic and without complication. We report a rare case of large frontal sinus osteoma with intracranial extension, associated with meningitis and the development of seizures. The patient is a 38-year-old man with a prolonged history of headache and seizures, who was seen by multiple specialists previously, all of whom deferred treatment. After years of worsening seizure activity, he finally underwent surgical resection of the lesion at our institution in a joint operation with neurosurgery and otolaryngology. We examine his course, presentation, and management, and examine the literature for cases of complicated sinus osteomas. This represents the fourth reported case of frontal sinus osteoma associated with meningitis. We believe this case demonstrates the value of a robust differential and a multidisciplinary approach

Primary Central Nervous System Lymphoma Presenting As Chronic Subdural Hematoma: Case Report and Review of the Literature

Primary central nervous system lymphoma (PCNSL) rarely manifests in immunocompetent patients. In such cases, these lesions may mimic more common intracranial bleeding or tumors. We present the case of an elderly patient who presented with a presumed chronic subdural hematoma (SDH); upon surgical intervention, an occult mass was discovered with no evidence of associated hematoma. Biopsy and immunohistochemistry demonstrated PCNSL. Literature review identified six other cases of PCNSL in immunocompetent adults that were initially suspected to be SDH but were finally diagnosed with PCNSL. Our literature review highlights the rarity these cases and the importance of distinguishing intracranial bleeds from PCNSL, as the latter can be treated with chemoradiation with good clinical outcomes

Hall Effect in ZnO Extrinsic Structure

Zinc oxide-based extrinsic composite was investigated. The sample was selected from a series of components of one production batch, prepared by standard sintering technology. The content of extrinsic elements in ZnO base was determined by SEM. Van der Pauw method with four-point electrode fixture was used for study of conducting phenomena in square-shaped sample. It is normaly preferred to assume the symmetric uniformity of the electrical properties of sample, for which sheet resistance, bulk resistivity and Hall mobility, sheet carrier density and carrier concentration can be calculated. When the uniformity of measured parameters is breached, the anisotropy in the arrangement of the internal structure may be the cause. There remains the question of whether the extrinsic ZnO material can be isotropic, regarding the electrical conductivity. Although the Hall effect has been measured, preliminary measurements indicate the presence of anisotropy in the measured samples. Before measurement the following phenomena should be taken into account: magneto-electric effect, photo-electric effect and the isothermal condition should be preserved. Paper discusses the uniformity deviations for the defined setup configurations for positive and negative magnetic field directions. Bulk resistivity has been calculated by numerical solution of van der Pauw equation. Large offset voltage during the measurement is discussed