Determining the level of global solar radiation on the earth's surface

The article analyzes the Earth's surface insolation. For the analysis, two methods are described - the method of approximate calculation and turbidity method using Linke turbidity index. The methods consider the latitude of current location on the Earth's surface, atmosphere attenuation and other major factors. To obtain more accurate values, long-term measurements at the current location should be obtained

Use of acoustic emission for testing resistance of hooves

This paper deals with the possibility of using an acoustic emission method for testing tensile strength of hooves. By using the acoustic emission (AE) method, we are able to locate degraded areas in hooves and then estimate the extent of degradation. In the experimental part, a sensor was used to record the emission signals, the measured data were processed and analysed, and the response of hooves to the applied mechanical load over time was monitored. Altogether, three samples were tested on the Zwick Z050/TH 3A materials testing machine and simultaneously the acoustic emissions were measured during testing.O

Technical aspects of new concentrating solar thermomechanic conversion

The article concerns technical aspects of new concentrating solar thermo-mechanic conversion from the point of view of automated control algorithms of solar thermal motor working on a principle of modified Clausius-Rankin's thermal circulation. On the basis of the proposed algorithms for controlling of thermodynamic processes of the functional model of the solar thermal motor, which uses internal-system absorption of incoming heat radiation, double-step steam generation and regeneration of out coming heat, the design and the testing of controlling single-chip microprocessor electronics with specially designed software was executed

Staničné elektrochemické akumulátory pre OZE

Place accumulation of elements in all systems is objectively necessary. Similarly, in the RES energy systems is their role is irreplaceable. The renewable energy systems can use different types of storage: electrochemical batteries, supercapacitors, superconducting units, rotary, pneumatic and others. The renewable energy systems can use different types of storage: electrochemical batteries, supercapacitors, superconducting units, rotary, pneumatic and others. The article deals with the design size sets of batteries to allow short-term deposit of the required amount of electricity.Miesto akumulačných prvkov vo všetkých systémoch je objektívne nevyhnutná. Rovnako aj v energetických systémoch OZE je ich úloha nenahraditeľná. V systémoch OZE je možné použiť rôzne typy zásobníkov: elektrochemické akumulátory, superkondenzátory, supravodičové jednotky, rotačné, tlakovzdušné a iné. Tieto zásobníky sú označované ako krátkodobé, aby zosúladili výrobu elektrickej energie a jej spotrebu. Článok sa zaoberá návrhom veľkosti zostavy akumulátorov tak, aby umožnili krátkodobé uloženie požadovaného množstva elektrickej energie

A new line-shape asymmetry model for wavelength modulation spectroscopy in gaseous flows

This communication reports technical notes on the development and application of an automated line-shape fitting procedure for wavelength modulation spectroscopy (WMS). Near-infrared transitions of carbon dioxide (CO2) around 1573 nm were measured in vertical cold (non-reacting) flow of CO2 at atmospheric pressure using WMS with demodulation at second harmonic frequency. Semi-empirical model based on the set of so-called Gabor functions was developed and parameters of Lorentzian line-shape profile and its asymmetry resulting from simultaneous frequency and amplitude response of the current-modulated semiconductor laser were determined. Nonlinear least-square fitting procedure employing differential evolution algorithm was successfully utilized for performing this task. Line-shape fitting procedure enabling efficient signal de-noising and background subtraction of wavelength modulation spectra was implemented into an open-source code.Web of Science18416115

One approach to adaptive control of a tubular chemical reactor

The paper deals with continuous-time adaptive control of a tubular chemical reactor with the countercurrent cooling as a nonlinear single input - single output process. The mean reactant temperature and the output reactant temperature are chosen as the controlled outputs, and, the coolant flow rate as the control input. The nonlinear model of the reactor is approximated by an external linear model with a structure chosen on the basis of controlled outputs step responses. Its parameters are estimated via corresponding delta model. The control system structure with two feedback controllers is considered. The resulting controllers are derived using polynomial approach. The method is tested on a mathematical model of the tubular chemical reactor

Silicon micro-levers and a multilayer graphene membrane studied via laser photoacoustic detection

Laser photoacoustic spectroscopy (PAS) is a method that utilizes the sensing of the pressure waves that emerge upon the absorption of radiation by absorbing species. The use of the conventional electret microphone as a pressure sensor has already reached its limit, and a new type of microphone - an optical microphone -has been suggested to increase the sensitivity of this method. The movement of a micro-lever or a membrane is sensed via a reflected beam of light, which falls onto a position-sensing detector. The use of one micro-lever as a pressure sensor in the form of a silicon cantilever has already enhanced the sensitivity of laser PAS. Herein, we test two types of home-made sensing elements - four coupled silicon micro-levers and a multi-layer graphene membrane - which have the potential to enhance this sensitivity further. Graphene sheets possess outstanding electromechanical properties and demonstrate impressive sensitivity as mass detectors. Their mechanical properties make them suitable for use as micro-/nano-levers or membranes, which could function as extremely sensitive pressure sensors. Graphene sheets were prepared from multilayer graphene through the micromechanical cleavage of basal plane highly ordered pyrolytic graphite. Multilayer graphene sheets (thickness similar to 10(2) nm) were then mounted on an additional glass window in a cuvette for PAS. The movements of the sheets induced by acoustic waves were measured using an He-Ne laser beam reflected from the sheets onto a quadrant detector. A discretely tunable CO2 laser was used as the source of radiation energy for the laser PAS experiments. Sensitivity testing of the investigated sensing elements was performed with the aid of concentration standards and a mixing arrangement in a flow regime. The combination of sensitive microphones and micromechanical/nanomechanical elements with laser techniques offers a method for the study and development of new, reliable and highly sensitive chemical sensing systems. To our knowledge, we have produced the first demonstration of the feasibility of using four coupled silicon micro-levers and graphene membranes in an optical microphone for PAS. Although the sensitivity thus far remains inferior to that of the commercial electret microphone (with an S / N ratio that is 5 times lower), further improvement is expected to be achieved by adjusting the micro-levers and membrane elements, the photoacoustic system and the position detector.Web of Science4110910

Geometric-Phase Microscopy for Quantitative Phase Imaging of Isotropic, Birefringent and Space-Variant Polarization Samples

We present geometric-phase microscopy allowing a multipurpose quantitative phase imaging in which the ground-truth phase is restored by quantifying the phase retardance. The method uses broadband spatially incoherent light that is polarization sensitively controlled through the geometric (Pancharatnam-Berry) phase. The assessed retardance possibly originates either in dynamic or geometric phase and measurements are customized for quantitative mapping of isotropic and birefringent samples or multi-functional geometric-phase elements. The phase restoration is based on the self-interference of polarization distinguished waves carrying sample information and providing pure reference phase, while passing through an inherently stable common-path setup. The experimental configuration allows an instantaneous (single-shot) phase restoration with guaranteed subnanometer precision and excellent ground-truth accuracy (well below 5nm). The optical performance is demonstrated in advanced yet routinely feasible noninvasive biophotonic imaging executed in the automated manner and predestined for supervised machine learning. The experiments demonstrate measurement of cell dry mass density, cell classification based on the morphological parameters and visualization of dynamic dry mass changes. The multipurpose use of the method was demonstrated by restoring variations in the dynamic phase originating from the electrically induced birefringence of liquid crystals and by mapping the geometric phase of a space-variant polarization directed lens