An experimental study of laboratory hybrid power system with the hydrogen technologies

This paper presents very small laboratory hybrid photovoltaic-hydrogen power system. The system was primarily assembled to verify the operability of the control algorithms and practical deployment of available commercial hydrogen technologies that are directly usable for storage of electricity produced from renewable energy sources in a small island system. This energetic system was installed and tested in Laboratory of fuel cells that is located in the university campus of VSB-Technical University of Ostrava. The energetic system consists of several basic components: a photovoltaic field, accumulators bank, water commercial electrolyzer and compact fuel cell system. The weather conditions recorded in two different weeks as model weather and solar conditions are used as case studies to test the energetic system and the results for two different cases are compared each other. The results show and illustrate selected behaviour curves of the power system and also average energy storage efficiency for accumulation subsystem based on hydrogen technologies or at the energetic system embedded components. On the basis of real measurement and its evaluation the ideal parameters of the photovoltaic field were calculated as well as the hydrogen technologies for supposed purpose and the power requirements

Lix@C60: Calculations of the Encapsulation Energetics and Thermodynamics

Li@C60 and Li@C70 can be prepared and thus, their calculations at higher levels of theory are also of interest. In the report, the computations are carried out on Li@C60, Li2@C60 and Li3@C60 with the B3LYP density-functional theory treatment in the standard 3-21G and 6-31G* basis sets. The computed energetics suggests that Lix @C60 species may be produced for a few small x values if the Li pressure is enhanced sufficiently. In order to check the suggestion, a deeper computational evaluation of the encapsulation thermodynamics is carried out

An investigation of thermoelectric generators used as energy harvesters in a water consumption meter application

In this study, we present the results of measuring the performance of selected Peltier cells such as thermoelectric Peltier cooler modules (TEC), thermoelectric micro-Peltier cooler modules (TES), and thermoelectric Seebeck generator modules (TEG). The achieved results are presented in the form of graphs of powering system output voltage or power efficiency functions of the load impedance. Moreover, a technical solution is also presented that consists of designing a water consumption power supply system, using a renewable energy source in the form of a Peltier cell. The developed measuring system does not require additional batteries or an external power source. The energy needed to power the system was obtained from the temperature difference between two sides of a thermoelectric cell, caused by the measured medium which was flowing in a copper water pipe. All achieved results were investigated for the temperature difference from 1 to 10 K in relation to the ambient temperature.Web of Science1413art. no. 376

Educational case study on H-infinity robust performance design

This paper deals with the design of a robust controller according to the H-infinity norm of mixed sensitivity functions. The motivation and origin are given by educational reasons. It compares how settings of individual weighting functions affect the quality of control when designing a sub-optimal controller. First, a controller for a system without uncertainty is considered (a nominal system representing a motor with a flexible clutch) and then the design is modified for a perturbated system with uncertainty in gain and also in the time constant.Web of Science28248748

Computations on Three Isomers of La@C 74

ABSTRACT: Density-functional theory calculations are presented for La@C 74 , where C 74 is either the IPR (isolated pentagon rule) cage or two cages with a pentagon-pentagon junction. Their relative thermodynamic production yields are evaluated using the calculated terms, and it is shown that the IPR-based endohedral prevails at relevant temperatures in agreement with the observation

Innovative bidirectional isolated high-power density on-board charge for vehicle-to-grid

This paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm(3), and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching, the switching frequency was set to 150 kHz. A laboratory prototype was built to verify the properties and operating principles of the described charger topology. The on-board charger has been tested in a microgrid test platform. Due to the parasitic properties of the transformer and other electronic components, overvoltage with subsequent oscillations occurred on the primary side of the transformer and damped resonance on its secondary side. These parasitic properties caused interference and especially voltage stress on the semiconductor elements. These undesirable phenomena have been eliminated by adding an active element to the charger topology and a new transistor control strategy. This new switching control strategy of transistors has been patented.Web of Science2221art. no. 847

Immunobiological properties of selected natural and chemically modified phenylpropanoids

Effects of natural and structurally transformed lignans compared with stilbenes or stilbenoids on production of nitric oxide (NO) triggered by lipopolysaccharide (LPS) and interferon-γ (IFN-γ), tested under in vitro conditions using murine resident peritoneal macrophages, are reviewed. Relation between the molecular structure and immunobiological activity was investigated, and implication of substituents, double bond stereochemistry, or cyclic attachments (double bond geometry fixation) was assessed. The focus was on lignans and stilbenoids because they were originally selected for a joint project of common interest to phytochemical and pharmacological investigation and because they represent well interesting and universally attractive groups of polyphenols with a feasible potential for therapeutic or nutraceutic utilization

Řízení přístupového systému s čipovými identifikačními kartami pomocí PLC Tecomat TC 500 a vizualizačního prostředí ControlWeb

Import 20/04/2006Prezenční výpůjčkaVŠB - Technická univerzita Ostrava. Fakulta elektrotechniky a informatiky. Katedra (455) měřící a řídící technik

Eu@C72: Computed Comparable Populations of Two Non-IPR Isomers

Relative concentrations of six isomeric Eu@C 72 —one based on the IPR C 72 cage (i.e., obeying the isolated-pentagon rule, IPR), two cages with a pentagon–pentagon junction (symmetries C 2 and C 2 v ), a cage with one heptagon, a cage with two heptagons, and a cage with two pentagon–pentagon fusions—are DFT computed using the Gibbs energy in a broad temperature interval. It is shown that the two non-IPR isomers with one pentagon–pentagon junction prevail at any relevant temperature and exhibit comparable populations. The IPR-satisfying structure is disfavored by both energy and entropy

Metodika vzdáleného monitorování chování plánovače operačních systémů reálného času

Import 28/04/2008Prezenční455 - Katedra měřicí a řídicí technikyNeuveden