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Number of results: 34
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Abstract

The problem of of the use of fly ash still constitutes a research and exploration area for scientists. This is due to the fact that, 6,000,000 Mg of coal combustion by-products (CCB) are storage on landfills yearly in Poland alone. One of the potential directions of using fly ash is to use it as a substrate in hydrothermal syntheses of mesoporous materials (synthetic zeolites). Zeolites are aluminosilicates with a spatial structure. Due to their specific structure they are characterized by a number of specific properties among others molecular-sieve, ion-exchange and catalytic that can be used in engineering and environmental protection. So far, the synthesis has been carried out using coal combustion by-products such as fly ash or microsphere. The article analyzes whether separation from the fly ash of the appropriate fraction (below 63 μm) will affect the formation of zeolite grains. The syntheses were carried out using class F fly ash and the fraction separated from it, which was obtained by sieving the ash through a 63 μm sieve. Chemical (XRF) and mineralogical (XRD, SEM-EDS) analyzes were carried out for substrates as well as the obtained reaction products. In the case of substrates, the analysis did not show any significant differences between the ash and the separated fraction. However, in products after synthesis (Na-X zeolite with a small amount of Na-P1 zeolite, and small amounts of quartz and unreacted aluminosilicate glass - mullite) higher aluminum and sodium contents were observed from the separated fraction, with a lower calcium and potassium content. A small proportion of illite was observed on the diffraction curve of the zeolite from the fraction. Observations of grain morphology showed no differences in formation. Based on the conducted analyzes, it can be stated that, considering the economics of the synthesis process, the separation of fine fractions from the fly ash does not affect the quality of the synthesis process.
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Abstract

The article is an attempt to analyze the spatio-pedagogical discourse of the German social pedagogy. It represents only a fragment of reflection on the turns in paradigm of place/ space (spatial turn), as pedagogical terms. & e authors seek to answer the question what is the space and place, and what concepts in the field of reflection on the place/space run in the German social pedagogy. The text introduces, inter alia, the relational concept of space developed by Martina Löw, duality of space and the concept of spacing. Active creation of urban space, the spatial dimension of the relationship and its dynamics are subjected to discussion. The article presents critical approach to the notion of transdisciplinary space, and space-oriented social work. Finally, it provides the incentive for in-depth, international analyzes of spatio-pedagogical theories.
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Abstract

Attempts to perform synthesis of a passive vibroinsulation two-mass system intended for the simultaneous reduction of machine frame vibrations and forces transmitted to foundations by supporting elements were undertaken in the study. In view of the variable frequency of the machine operation, it was necessary for the frequency interval, encompassed by the vibroinsulation system operation, to be within given limits. On the grounds of properties of the linear massive-elastic system formulated in the works of Genkin and Ryaboy (1998), the problem of vibroinsulation system synthesis was formulated in the parametric type optimisation approach with equality and inequality limitations. For piston compressor vibroinsulation, the mass and elasticity matrices of the vibroinsulating system, as well as its physical structure, were determined. Its operation was verified on the basis of simulation investigations, taking into account the system loss and transient states.
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Abstract

In the paper we consider fast transformation of a multilevel and multioutput circuit with AND, OR and NOT gates into a functionally equivalent circuit with NAND and NOR gates. The task can be solved by replacing AND and OR gates by NAND or NOR gates, which requires in some cases introducing the additional inverters or splitting the gates. In the paper the quick approximation algorithms of the circuit transformation are proposed, minimizing number of the inverters. The presented algorithms allow transformation of any multilevel circuit into a circuit being a combination of NOR gates, NAND gates or both types of universal gates.
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Abstract

In the paper the squared voltage-current functionals are minimized, which represent the global power losses in the network. In that way it is possible to find the voltage-current distributions on the net without the use of immitance operators and basing only on the Kirchhoff laws. Farther the individual branch parameters are defined in the syntheses process. Many optimal power analysis examples are also shown to illustrate the thesis included in the paper.
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Abstract

The paper deals with linear circuits synthesis with periodic parameters. It was proved that the time-varying voltages and currents of inner branches of such circuits can be calculated using linear recursive equations with periodic coefficients if signals on port are given. The stability theorem of periodic solution was formulated. Hereby described the synthesis problems appear when compensation of power supply systems is considered.
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Abstract

Nano-sized yttria (Y2O3) powders were synthesized by a polymer solution route using polyvinyl alcohol (PVA) as an organic carrier. The PVA polymer affected the dispersion of yttrium ions in precursor sol. In this study, three kinds of PVA polymer (different molecular weight) were applied for synthesis of yttria powder. The PVA type as well as calcination temperature had a strongly influence on the particle morphology. Single crystal nano wire particles were observed at the temperature of polymer burn out range and the size was dependent on the PVA type. The stable, fully crystallized yttria powder was obtained through the calcination at 800°C for 1 h. The yttria powder prepared with the high weight PVA (MW: 153,000) revealed a particle size of 30 nm with a surface area of 18.8 m2/g.
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Abstract

Polish Academy of Sciences, Institute of Chemical Engineering, 44-100 Gliwice, Bałtycka 5, Poland A review concerning main processes of hydrogenation of carbon oxides towards synthesis of methanol, mixture of methanol and higher aliphatic alcohols and one-step synthesis of dimethyl ether as well as methanol steam reforming is given. Low-temperature methanol catalysts and lowtemperature modified methanol catalysts containing copper as primary component and zinc as secondary one are described.
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Abstract

Because of excellent properties, similar to natural bone minerals, and variety of possible biomedical applications, hydroxyapatite (HAp) is a valuable compound among the calcium phosphate salts. A number of synthesis routes for producing HAp powders have been reported. Despite this fact, it is important to develop new methods providing precise control over the reaction and having potential to scale-up. The main motivation for the current paper is a view of continuous synthesis methods toward medical application of produced hydroxyapatite, especially in the form of nanoparticles.
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Abstract

In August 2016, tomato plants grown during a hot, wet summer with heavy soil flooding, displaying symptoms of wilting, dead plant, root rot with crown and stem rot, at Beni Suef and Fayoum governorates were examined. A number of 16 fungal isolates were isolated from tomato plants displaying the above symptoms. These isolates were classified as belonging to six species, namely: Alternaria solani, Chaetomium globosum, Fusarium solani, Fusarium oxysporum, Pythium spp. and Rhizoctonia solani. Isolates of Pythium spp. were prevalent and were found to be more pathogenic than the other fungal isolates. This species causes damping-off, root rot, sudden death, stem rot and fruit rot. The pathogen was identified as Pythium aphanidermatum based on morphological, cultural, and molecular characteristics. Biogenic silver nanoparticles (AgNPs) were produced using the F. oxysporum strain and characterized by transmission electron microscopy (TEM). The size of these spherical particles ranged from 10 to 30 nm. In vitro, biogenic AgNPs showed antifungal activity against P. aphanidermatum. In greenhouse and field experiments, AgNPs treatment significantly reduced the incidence of dead tomato plants due to root rot caused by P. aphanidermatum compared to the control. All of the investigated treatments were effective and the treatment of root dipping plus soil drenching was the most effective. To the best of our knowledge, this study describes P. aphanidermatum on tomato in Egypt for the first time. Also, biogenic AgNPs could be used for controlling root rot disease caused by this pathogen.
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Abstract

Preparation and properties of hierarchically structured porous silica monoliths have been discussed from the viewpoint of their application as continuous microreactors for liquid-phase synthesis of fine chemical in multi kilogram scales. The results of recent topical papers published by two research teams of Institute of Chemical Engineering Polish Academy of Sciences (ICE) and Department of Chemical Engineering and Process Design, Chemical Faculty, Silesian University of Technology (SUT) have been analyzed to specify the governing traits of microreactors. It was concluded that even enhancement factor of 100 in activity, seen in enzyme catalyzed reactions, can be explained by a proportional reduction of its physical constraints, i.e. huge enhancement of external mass transfer and micromixing. It is induced by very chaotic flows of liquid in tens of thousands of waving connected channels of ca. 25–50 mm in diameter, present in the skeleton. The scale of enhancement in the case of less active catalysts was smaller, but still large enough to consider the most practical applications.
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Abstract

In this paper, a modified form of the Gabor Wigner Transform (GWT) has been proposed. It is based on adaptive thresholding in the Gabor Transform (GT) and Wigner Distribution (WD). The modified GWT combines the advantages of both GT and WD and proves itself as a powerful tool for analyzing multi-component signals. Performance analyses of the proposed distribution are tested on the examples, show high resolution and crossterms suppression. To exploit the strengths of GWT, the signal synthesis technique is used to extract amplitude varying auto-components of a multi-component signal. The proposed technique improves the readability of GWT and proves advantages of combined effects of these signal processing techniques.
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Abstract

In this paper, we present a synthesis of the parameters of the fiber Bragg grating (FBG) and the reconstruction of the distributed strain affecting the grating, performed by means of its reflection spectrum. For this purpose, we applied the transition matrix method and the Nelder-Mead nonlinear optimization method. Reconstruction results of the strain profile carried out on the basis of a simulated reflection spectrum as well as measured reflection spectrum of the FBG indicate good agreement with the original strain profile; the profile reconstruction errors are within the single digit percentage range. We can conclude that the Nelder-Mead optimization method combined with the transition matrix method can be used for distributed sensing problems.
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Abstract

In this paper a new pitch shifter using a complex instantaneous frequency rescaler and direct digital synthesizer is presented aimed at an application in a handset calling signal composer. The pitch shifter introduced here exhibits an excellent performance as a generator of different melodies, where the sound of each note in a melody, e.g., imitating a popular hit, is derived from a short recording of a voice of a chosen creature via complex dynamic representation processing.
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Abstract

A rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated in the present research. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are injected into the reactor from centres of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction multicomponent transport model with the CFD software ANSYS©Fluent v. 13.0. Effect of operating conditions on TG conversion is particularly investigated. Simulation results indicate that there is occurrence of back flow close to the stator at the outlet zone. Small gap size and fast rotational speed generally help to intensify mixing among reagents, and consequently enhance TG conversion. However, increasing rotational speed of spinning disk leads to more backflow, which decreases TG conversion. Large flow rate of TG at inlet is not recommended as well because of the short mean residence time of reactants inside the reactor.
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Abstract

The results of activity studies of four catalysts in methanol synthesis have been presented. A standard industrial catalyst TMC-3/1 was compared with two methanol catalysts promoted by the addition of magnesium and one promoted by zirconium. The kinetic analysis of the experimental results shows that the Cu/Zn/Al/Mg/1 catalyst was the least active. Although TMC-3/1 and Cu/Zn/Al/Mg/2 catalysts were characterised by a higher activity, the most active catalyst system was Cu/Zn/Al/Zr. The activity calculated for zirconium doped catalyst under operating conditions was approximately 30% higher that of TMC-3/1catalyst. The experimental data were used to identify the rate equations of two types - one purely empirical power rate equation and the other one - the Vanden Bussche & Froment kinetic model of methanol synthesis. The Cu/ZnO/Al2O3 catalyst modified with zirconium has the highest application potential in methanol synthesis.
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Abstract

Available methods for room-related sound presentation are introduced and evaluated. A focus is put on the synthesis side rather than on complete transmission systems. Different methods are compared using common, though quite general criteria. The methods selected for comparison are: Intensity Stereophony after Blumlein, vector-base amplitude panning (VBAP), 5.1-Surround and its discrete-channel derivatives, synthesis with spherical harmonics (Ambisonics, HOA), synthesis based on the boundary method, namely, wave-field synthesis (WFS), and binaural-cue selection methods (e.g., DiRAC). While VBAP, 5.1-Surround and other discrete-channel-based methods show a number of practical advantages, they do, in the end, not aim at authentic sound-field reproduction. The so-called holophonic methods that do so, particularly, HOA and WFS, have specific advantages and disadvantages which will be discussed. Yet, both methods are under continuous development, and a decision in favor of one of them should be taken from a strictly application-oriented point of view by considering relevant application-specific advantages and disadvantages in detail.
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Abstract

In this paper a two-disc spinning disc reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat discs, located coaxially and parallel to each other with a gap of 0.2 mm between the discs. The upper disc is located on a rotating shaft while the lower disc is stationary. The feed liquids, triglycerides (TG) and methanol are introduced coaxially along the centre line of rotating disc and stationary disc. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction species transport model by the CFD software ANSYS©Fluent v. 13.0. The effect of the upper disc’s spinning speed is evaluated. The results show that the rotational speed increase causes an increase of TG conversion despite the fact that the residence time decreases. Compared to data obtained from adequate experiments, the model shows a satisfactory agreement.
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Abstract

Two different complexing agents, namely citric acid and gelatin, were used for gel-combustion synthesis of yttria stabilized zirconia. The influence of synthesis conditions on properties of powders and sintered bodies was studied by X-ray Diffraction Analysis (XRD), Scanning Electron Microscope (SEM) and helium pycnometer measurements.
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Abstract

A method for manufacturing of Al-Si alloy (EN AC-44200) matrix composite materials reinforced with MAX type phases in Ti-Al-C systems was developed. The MAX phases were synthesized using the Self-propagating High-Temperature Synthesis (SHS) method in its microwave assisted mode to allow Ti2AlC and Ti3AlC2 to be created in the form of spatial structures with open porosity. Obtained structures were subjected to the squeeze casting infiltration in order to create a composite material. Microstructures of the produced materials were observed by the means of optical and SEM microscopies. The applied infiltration process allows forming of homogeneous materials with a negligible residual porosity. The obtained composite materials possess no visible defects or discontinuities in the structure, which could fundamentally deteriorate their performance and mechanical properties. The produced composites, together with the reference sample of a sole matrix material, were subjected to mechanical properties tests: nanohardness or hardness (HV) and instrumental modulus of longitudinal elasticity (EIT).
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Abstract

In the paper, two preprocessing methods for virtual view synthesis are presented. In the first approach, both horizontal and vertical resolutions of the real views and the corresponding depth maps are doubled in order to perform view synthesis on images with densely arranged points. In the second method, real views are filtered in order to eliminate blurred or improperly shifted edges of the objects. Both methods are performed prior to synthesis, thus they may be applied to different Depth-Image-Based Rendering algorithms. In the paper, for both proposed methods, the achieved quality gains are presented.
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Abstract

In this paper, a modification of the graph-based depth estimation is presented. The purpose of proposed modification is to increase the quality of estimated depth maps, reduce the time of the estimation, and increase the temporal consistency of depth maps. The modification is based on the image segmentation using superpixels, therefore in the first step of the proposed modification a segmentation of previous frames is used in the currently processed frame in order to reduce the overall time of the depth estimation. In the next step, a depth map from the previous frame is used in the depth map optimization as the initial values of a depth map estimated for the current frame. It results in the better representation of silhouettes of objects in depth maps and in the reduced computational complexity of the depth estimation process. In order to evaluate the performance of the proposed modification the authors performed the experiment for a set of multiview test sequences that varied in their content and an arrangement of cameras. The results of the experiments confirmed the increase of the depth maps quality — the quality of depth maps calculated with the proposed modification is higher than for the unmodified depth estimation method, apart from the number of the performed optimization cycles. Therefore, use of the proposed modification allows to estimate a depth of the better quality with almost 40% reduction of the estimation time. Moreover, the temporal consistency, measured through the reduction of the bitrate of encoded virtual views, was also considerably increased.
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Abstract

The synthesis problem for optimal control systems in the class of discrete controls is under consideration. The problem is investigated by reducing to a linear programming (LP) problem with consequent use of a dynamic version of the adaptive method of LP. Both perfect and imperfect information on behavior of control system cases are studied. Algorithms for the optimal controller, optimal estimators are described. Results are illustrated by examples.
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Abstract

This paper reviews parametric audio coders and discusses novel technologies introduced in a low-complexity, low-power consumption audio decoder and music synthesizer platform developed by the authors. The decoder uses parametric coding scheme based on the MPEG-4 Parametric Audio standard. In order to keep the complexity low, most of the processing is performed in the parametric domain. This parametric processing includes pitch and tempo shifting, volume adjustment, selection of psychoacoustically relevant components for synthesis and stereo image creation. The decoder allows for good quality 44.1 kHz stereo audio streaming at 24 kbps. The synthesizer matches the audio quality of industry-standard sample-based synthesizers while using a twenty times smaller memory footprint soundbank. The presented decoder/synthesizer is designed for low-power mobile platforms and supports music streaming, ringtone synthesis, gaming and remixing applications.
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Abstract

The aim of this paper is to present methods of digitally synthesising the sound generated by vibroacoustic systems with distributed parameters. A general algorithm was developed to synthesise the sounds of selected musical instruments with an axisymmetrical shape and impact excitation, i.e., Tibetan bowls and bells. A coupled mechanical-acoustic field described by partial differential equations was discretized by using the Finite Element Method (FEM) implemented in the ANSYS package. The presented synthesis method is original due to the fact that the determination of the system response in the time domain to the pulse (impact) excitation is based on the numerical calculation of the convolution of the forcing function and impulse response of the system. This was calculated as an inverse Fourier transform of the system’s spectral transfer function. The synthesiser allows for obtaining a sound signal with the assumed, expected parameters by tuning the resonance frequencies which exist in the spectrum of the generated sound. This is accomplished, basing on the Design of Experiment (DOE) theory, by creating a meta-model which contains information on its response surfaces regarding the influence of the design parameters. The synthesis resulted in a sound pressure signal in selected points in space surrounding the instrument which is consistent with the signal generated by the actual instruments, and the results obtained can improve them.
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