Impact of fuel quality and burner capacity on the performance of wood pellet stove

Pellet stoves may play an important role in Serbia in the future when fossil fuel fired conventional heating appliances are replaced by more efficient and environmentally friendly devices. Experimental investigation was conducted in order to examine the influence of wood pellet quality, as well as burner capacity (6, 8, and 10 kW), used in the same stove configuration, on the performance of pellet stove with declared nameplate capacity of 8 kW. The results obtained showed that in case of nominal load and combustion of pellets recommended by the stove manufacturer, stove efficiency of 80.03% was achieved The use of lower quality pellet caused additional 1.13 kW reduction in heat output in case of nominal load and 0.63 kW in case of reduced load This was attributed to less favourable properties and lower bulk and particle density of lower quality pellet. The use of different burner capacity has shown to have little effect on heat output and efficiency of the stove when pre-set values in the control system of the stove were not altered It is concluded that replacement of the burner only is not sufficient to increase/decrease the declared capacity of the same stove configuration, meaning that additional measures are necessaly. These measures include a new set-up of the stove control system, which needy to be properly adjusted for each alteration in stove configuration. Without the adjustment mentioned, declared capacity of the stove cannot be altered, while its CO emission shall be considerably increase

Determination of Microstructural Changes By Severely Plastically Deformed Copper-Aluminum Alloy: Optical Study

Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metal-matrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of Cu, CuO, Cu2O, Cu4O3 or Al2O3 structural characteristics, depending on type of sample

Masonry walls with a multi-layer bed joint subjected to in-plane cyclic loading: An experimental investigation

ISSN:0141-029

Contactless real-time heartbeat detection via 24 ghz continuous-wave doppler radar using artificial neural networks

The measurement of human vital signs is a highly important task in a variety of environments and applications. Most notably, the electrocardiogram (ECG) is a versatile signal that could indicate various physical and psychological conditions, from signs of life to complex mental states. The measurement of the ECG relies on electrodes attached to the skin to acquire the electrical activity of the heart, which imposes certain limitations. Recently, due to the advancement of wireless technology, it has become possible to pick up heart activity in a contactless manner. Among the possible ways to wirelessly obtain information related to heart activity, methods based on mm-wave radars proved to be the most accurate in detecting the small mechanical oscillations of the human chest resulting from heartbeats. In this paper, we presented a method based on a continuous-wave Doppler radar coupled with an artificial neural network (ANN) to detect heartbeats as individual events. To keep the method computationally simple, the ANN took the raw radar signal as input, while the output was minimally processed, ensuring low latency operation (<1 s). The performance of the proposed method was evaluated with respect to an ECG reference (“ground truth”) in an experiment involving 21 healthy volunteers, who were sitting on a cushioned seat and were refrained from making excessive body movements. The results indicated that the presented approach is viable for the fast detection of individual heartbeats without heavy signal preprocessing

Competition over collective victimhood recognition in Belgium, Poland, Hungary and Serbia

info:eu-repo/semantics/nonPublishe

Far-infrared spectroscopy of Cd1-xMnxS quantum dots

Far-infrared reflectivity spectra, in spectral region 50-600 cm(-1) and temperature region 80-300 K, of CdS and Cd1-xMnxS nanocrystals embedded in hexametaphosphate, are presented. The analysis of the far-infrared experimental reflectivity spectrum was made by the fitting procedure. The Maxwell-Garnet effective medium theory is used for modeling an effective dielectric function as well as to separate respond from nanoparticles. To analyze spectra in CdS omega(TO)(approximate to 238 cm(-1)) to omega(TO)(approximate to 305 cm(-1)) spectral region, quantized dipolar modes in a spherical isotropic material quantum dot (QD) are considered in the framework of a continuum model. As to the mechanical boundary conditions rigid sphere is concerned. Experimental far-infrared reflectivity spectra of our samples are in general agreement with the predictions of this model. Experimentally registered and through fitting procedure located features for CdS nanoparticles in spectral region below CdS omega(TO) at: approximate to 102 cm(-1), approximate to 135 cm(-1), approximate to 170 cm(-1) and approximate to 210 cm(-1) are associated to defect induced modes, especially to defects located near the surface of CdS QD. In region over CdS omega(LO), modes are identified as multiphonons. In Cd1-xMnxS QD spectra new reflectivity peaks are at: approximate to 85 cm(-1), approximate to 110 cm(-1) and approximate to 180 cm(-1) in spectral region below CdS omega(TO), approximate to 270 cm(-1) inside CdS omega(TO)-omega(LO) spectral region and approximate to 356 cm(-1) and approximate to 376 cm(-1) in region over CdS omega(LO). First two registered modes are associated to both mass and force constant defects at the surface, and rest four modes are consequence of MnS phases present in the sample. (C) 2012 Published by Elsevier B.V

Magnetic field influence on optical properties of Cd1-xMnxS (x=0; 0.3) quantum dots: Photoluminescence study

We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5 nm. These materials have been studied using photoluminescence spectroscopy with various excitation energies in the temperature range from 1.8 to 300 K, in magnetic field up to 5T. We registered surface and defect states as well as two Mn2+ energy levels that correspond to Mn2+ ions in two different crystal environments. We proposed the scheme of energy levels and transitions that explain obtained experimental results. (C) 2012 Elsevier B. V. All rights reserved

Structural properties and luminescence kinetics of white nanophosphor YAG:Dy

Dysprosium (Dy3+ ions) doped YAG nanopowders were prepared by the solution combustion synthesis (SCS) method and undoped yttrium aluminum garnet (YAG, Y3Al5O12) single crystal was grown by the Czochralski technique. The structure of the prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) spectroscopy. PL spectra were acquired using Optical Parametric Oscillator (OPO) excitation tuned at 350 nm. Several emission bands in Dy3+ emission spectrum were observed in the blue (470-500 nm), yellow (560-600 nm), red (660-685 nm) and infra-red (750-780 nm) regions, corresponding to F-4(9/2)-H-6(15/2), F-4(9/2)-H-6(13/2), F-4(9/2)-H-6(11/2), F-4(9/2)-(H-6(9/2) + H-6(11/2)) transitions in the 4f levels of Dy3+ ions, respectively. By using the Commission Internationale de lEclairage (CIE) chromaticity diagram of emission spectra it has been shown that this material can be used as a source of a white light. The result of lifetime analysis of the F-4(9/2) level in dysprosium ion has been reported, as well. (C) 2015 Elsevier B.V. All rights reserved

Determination of magneto-optical quality and refractive index of bismuth germanium oxide single crystals grown by Czochralski technique

Bi12GeO20 single crystals were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. As a result of our experiments, the pale yellow and black single crystals were produced. The structure of the Bi12GeO20 has been investigated by X-ray diffraction, Raman and IR spectroscopy. The atomic ratio Bi/Ge was determined for the both crystals. The refractive indexes of both Bi12GeO20 crystals were determined by the spectroscopic ellipsometry method. Important properties of Bi12GeO20 for sensing applications, optical activity, Faraday rotation and absorption were measured and magneto optical quality was calculated and compared. (c) 2012 Elsevier B.V. All rights reserved

Structural and optical properties of CuSe2 nanocrystals formed in thin solid Cu-Se film

This paper describes the structural and optical properties of Cu-Se thin films. The surface morphology of thin films was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Formation of Cu-Se thin films is concluded to proceed unevenly, in the form of islands which later grew into agglomerates. The structural characterization of Cu-Se thin film was investigated using X-ray diffraction pattern (XRD). The presence of two-phase system is observed. One is the solid solution of Cu in Se and the other is low-pressure modification of CuSe2. The Raman spectroscopy was used to identify and quantify the individual phases present in the Cu-Se films. Red shift and asymmetry of Raman mode characteristic for CuSe2 enable us to estimate nanocrystal dimension. In the analysis of the far infrared reflection spectra, numerical model for calculating the reflectivity coefficient of layered system, which includes film with nanocrystalite inclusions (modeled by Maxwell -Garnett approximation) and substrate, has been applied. (C) 2016 Elsevier B.V. All rights reserved