bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquisolid systems and aspects influencing their research and development
Authors: Vraníková Barbora , Gajdziok Jan
Published: January 2014

Many modern drugs are poorly water soluble substances, which causes difficulties in the development of solid dosage forms with sufficient bioavailability. Preparation of liquisolid systems (LSS) is a novel technique for improving solubility, dissolution and bioavailability of such drugs. The basic principle of LSS preparation is conversion of the drug in liquid state into a free-flowing, compressible, dry powder through its absorption into suitable excipients - porous carriers (aluminometasilicates, microcrystalline cellulose), subsequently coated with material having high absorption capacity (silicon dioxide commonly known as colloidal silica). LSS exhibit advantages such as lower production costs compared to soft capsules, simple processing and enhanced drug release. The main benefit is higher bioavailability of the liquid drug, caused by a large surface area available for absorption. The article tries to clarify specific aspects connected with the formulation of LSS: properties of excipients (surface area, absorption capacity), variables related to the processing (solubility, liquid load factor) and dosage form evaluation.
Chemical fingerprinting and quantitative analysis of two common Gleditsia sinensis fruits using HPLC-DAD
Authors: Chen Jianping , Li Zhonggui , Zheng Ken Y. Z. , Guo Ava J. Y. , Zhu Kevin Y. , Zhang Wendy L. , Zhan Janis Y. X. , Dong Tina T. X. , Su Ziren , Tsim Karl W. K.
Published: January 2014

Gleditsiae Fructus Abnormalis and Gleditsiae Sinensis Fructus are obtained from different developmental stages of fruits from Gleditsia sinensis Lam. (Leguminosae). The possible interchangeable usage of the two fruits, however, has long been very controversial. Here, high performance liquid chromatography coupled with diode array detection was developed to explore their chemical fingerprinting profiles. Besides, the amounts of aglycones of saponin compounds, echinocystic acid and oleanolic acid in both fruits were quantified. The results indicated that there was no significant difference in the content of aglycones from the two types of fruits. However, their chromatographic fingerprints showed distinct characteristics. Therefore, the interchangeable application of these fruits has to be taken with a specific precaution.
On variation in Schloenbachia varians (J. Sowerby, 1817) from the Lower Cenomanian of western Kazakhstan
Authors: Kennedy William James
Published: January 2014

Kennedy, W.J. 2013. On variation in Schloenbachia varians (J. Sowerby, 1817) from the Lower Cenomanian of western Kazakhstan Acta Geologica Polonica, 63(4), 443-468. Warszawa. An assemblage of 94 specimens of Schloenbachia varians (J. Sowerby, 1817) from the Lower Cenomanian Sharpeiceras schlueteri Subzone of the Mantelliceras mantelli Zone of the Besakty section in the Mangyshlak Mountains of western Kazakhstan includes 26 complete adults that range from to 59-174 mm in diameter. No size-related dimorphism was detected in the assemblage, which shows wide, continuous intraspecific variation. This is described in terms of five formae; from robust to gracile these are: ventriosa, varians sensu stricto, subtuberculata , intermedia, and subplana. The ratio of robust (ventriosa + varians sensu stricto) to gracile (subtuberculata + intermedia + subplana) individuals is 34% to 66%. The reference specimens of the formae and their synonyms are described and illustrated, and related to the Besakty material. The modification of adult body chamber ornament of all formae is documented, and Jakeiceras Cooper and Owen, 2011 is shown to be based on an adult of a passage form between forma subtuberculata and forma intermedia. The differences between Lower Cenomanian S. varians, lower Middle Cenomanian S. coupei (Brongniart, 1822), and upper Middle and lower Upper Cenomanian S. lymensis Spath, 1926b are described and illustrated.
Inoceramid and foraminiferal record and biozonation of the Turonian and Coniacian (Upper Cretaceous) of the Mangyshlak Mts., western Kazakhstan
Authors: Walaszczyk Ireneusz , Kopaevich Ludmila F. , Beniamovski Vladimir N.
Published: January 2014

Walaszczyk, I., Kopaevich, L.F. and Beniamovski, V.N. 2013. Inoceramid and foraminiferal record and biozonation of the Turonian and Coniacian (Upper Cretaceous) of the Mangyshlak Mts., western Kazakhstan. Acta Geologica Polonica, 63 (4), 469-487. Warszawa.

The Turonian and Coniacian (Upper Cretaceous) of the Mangyshlak Mts., western Kazakhstan, yielded a rich and relatively complete inoceramid bivalve record. The faunas and their succession correspond to those known from central and eastern Europe, allowing the zonation established in the latter areas to be applied in a virtually identical form. The gaps in the record of the group in Mangyshlak stem from the regional hiatuses in the geological record in the area and do not reflect any biogeographical differences between eastern and central-western Europe. Planktonic foraminifera are rare. Four successive interval range zones can be distinguished: in ascending stratigraphic order, the Helvetoglobotrunaca helvetica, Marginotruncaca pseudolinneiana, Marginotruncana coronata, and Concavotruncana concavata zones. Their correlation with the inoceramid zonation and, consequently, with the chronostratigraphic scheme, is demonstrated. The zonation and chronostratigraphic subdivision as applied in Mangyshlak may easily be applied to other areas of the peri-Caspian region (Caucasus, Tuarkyr, Kopet-Dagh, SE margin of the East-European Craton).
MATERIAL AND THERMAL ANALYSIS OF LASER SINTERTED PRODUCTS
Authors: Hudák Radovan , Šarik Martin , Dadej Róbert , Živčák Jozef , Harachová Daniela
Published: January 2014

Thermal analysis of laser processes can be used to predict thermal stresses and consequently deformation in a completed part. Analysis of temperature is also the basic for feedback of laser processing parameters in manufacturing. The quality of laser sintered parts greatly depends on proper selection of the input processing parameters, material properties and support creation. In order to relatively big heat stress in the built part during sintering process, the thermal simulation and thermal analysis, which could help better understand and solve the issue of parts deformations is very important. Main aim of presented work is to prepare input parameters for thermal simulations by the use of RadTherm software (Thermoanalytics Inc., USA), directly during the sintering process and after the process and find out the impact of the heat stress on a final shape and size of the prototype. Subsequently, an annealing process of constructed products after DMLS could be simulated and specified.
TRANSIENT PLANE WAVES IN MULTILAYERED HALF-SPACE
Authors: Turchyn Ihor , Turchyn Olga
Published: January 2014

Considered the dynamic problem of the theory of elasticity for multilayered half-space. Boundary surface of inhomogeneous half-space loaded with normal load, and the boundaries of separation layers are in conditions of ideal mechanical contact. The formulation involves non-classical separation of equations of motion using two functions with a particular mechanical meaning volumetric expansion and function of acceleration of the shift. In terms of these functions obtained two wave equation, written boundary conditions and the conditions of ideal mechanical contact of layers. Using the Laguerre and Fourier integral transformations was obtained the solution of the formulated problem. The results of the calculation of the stress-strain state in the half-space with a coating for a local impact loading are presented.
RHEOLOGICAL PROPERTIES OF MR FLUIDS RECOMMENDED FOR USE IN SHOCK ABSORBERS
Authors: Sapiński Bogdan , Horak Wojciech
Published: January 2014

The paper summarises the results of laboratory testing of rheological behaviour of (magnetorheological) MR fluids designed for use in shock absorber and vibration dampers. The experiments used a rotational rheometer with an extra chamber inside which a uniform magnetic field can be generated. Underlying the description of rheological properties of fluids is the Herschel-Bulkley’s model of viscous- plastic substances. The aim of the experiment was to determine the shear stress, yield stress, the yield factor and the power-law exponent depending on the magnetic flux density, followed by the comparative study of rheological parameters of investigated fluids.
THE SENSITIVITY OF A PHOTOGRAMMETRIC METHOD IN FORMABILITY ANALYSIS
Authors: Slota Ján , Jurčišin Miroslav , Gajdoš Ivan , Spišák Emil
Published: January 2014

Nowadays is a possible to implement numerical simulation and photogrammetric inspection to the complex process chain of inspection. In the recent years there has been significant progress in accuracy improving of these methods of inspection in pre-production or post-production stage of manufacturing. This article discusses these two methods from sensitivity and comparison point of view. Most attention has been paid to the photogrammetric method and his sensitivity to using different approaches. Results were compared with the result of numerical simulation and experiment. Numerical simulation was performed in static implicit finite element code Autoform. For this purpose, GPS cover of galvanized steel of DQ category was used for inspection. In this paper was proved that photogrammetric method of strain measurement is highly sensitive on the various external factors. Further results and findings are included in the next chapters of this paper
DESIGN CONCEPT OF TEST STAND FOR DETERMINING PROPERTIES OF MAGNETORHEOLOGICAL ELASTOMERS
Authors: Bocian Mirosław , Kaleta Jerzy , Lewandowski Daniel , Przybylski Michał
Published: January 2014

Magnetorheological elastomers (MRE) are “SMART” materials that change their mechanical properties under influence of magnetic field. Thanks to that ability it is possible to create adaptive vibration dampers based on the MRE. To test vibration damping abilities of this material special test stand is required. This article presents design concept for such test stand with several options of testing.
ASSESSMENT TRIBOLOGICAL PROPERTIES OF COATINGS APPLIED BY HVOF TECHNOLOGY
Authors: Brezinová Janette , Guzanová Anna , Draganovská Dagmar , Egri Marián
Published: January 2014

In this article, the attention is paid to the HVOF (High Velocity Oxygen Fuel) thermal spraying method by which the progressive coatings are applied on basic material C15E (STN 412020). These coatings are based on C-17CO, WC-CO-Cr and Cr3C2-25NiCr. There was made determination of the chemical composition of the coatings and assessment of coatings quality - adhesion, microhardness, porosity and wear resistance at room temperature (21°C) and also at operational elevated temperature (900°C). Results of adhesive wear showed high quality of all evaluated coatings and their suitability to extreme tribological conditions.
IDENTIFICATION OF LAYERS DISTRIBUTION IN THE COMPOSITE COUPON USING FINITE ELEMENT METHOD AND THREE POINT BENDING TEST
Authors: Mazurkiewicz Łukasz , Małachowski Jerzy , Damaziak Krzysztof , Baranowski Paweł , Gotowicki Paweł
Published: January 2014

The main objective of the study is to develop experimentally validated FE model and perform numerical analysis of layered composites made by hand lay-up techniques during tension and bending test. The research object is glass - polyester laminate made of four unidirectional layers. In order to validate the numerical models experimental test were performed. Due to the very different stiffness modulus in tension and bending loading the material properties obtained from standard test are not suitable to apply in numerical model. Significantly different behaviour compared to experimental test was obtained for tree point bending where the numerical model becomes too stiff. Simple coupons, relatively easy to manufacture presented in the paper have very low quality. The differences in actual and theoretical bending stiffness (obtained from tension stiffness) exceed 70%. In order to represent the actual structure the layers of the composite were divided by resin layers and also additional resin layer at the top and bottom of the model were defined. Single stage optimization process was used to adjust the material layout. After layer set-up modification very significant improvement can be seen for flexural behaviour
SIMULATION OF POWDER SINTERING USING A DISCRETE ELEMENT MODEL
Authors: Rojek Jerzy , Nosewicz Szymon , Pietrzak Katarzyna , Chmielewski Marcin
Published: January 2014

This paper presents numerical simulation of powder sintering. The numerical model introduced in this work employs the discrete element method which assumes that material can be modelled by a large assembly of discrete elements (particles) of spherical shape interacting among one another. Modelling of sintering requires introduction of the cohesive interaction among particles representing interparticle sintering forces. Numerical studies of sintering have been combined with experimental studies which provided data for calibration and validation of the model. In the laboratory tests evolution of microstructure and density during sintering have been studied. Comparison of numerical and experimental results shows a good performance of the numerical model developed
The Influence of the Microstructure on the Switching Properties of Ag C, Ag-WC-C and Ag-W-C Contact Materials
Authors: Wójcik-Grzybek D. , Frydman K. , Borkowski P.
Published: January 2014

The correlation between the microstructure of Ag-C, Ag-WC-C and AgWC composites and their switching properties was investigated. Two methods were used to manufacture the starting powder mixtures, namely classical milling and mechanical alloying . The arc erosion, contact resistance and welding forces of the contact materials obtained by different methods were measured using model devices. This paper presents the results achieved for the tested materials. It was found that weight loss was lower for the contacts produced by high energy milling
Oxygen in Steel WMD after Welding with Micro-Jet Cooling
Authors: Wegrzyn T. , Piwnik J. , Hadrys D.
Published: January 2014

Until that moment micro-jet technology was tested only for MIG welding process with argon as a shielded gas. An article presents actual information about innovate welding technology with micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of oxygen amount in WMD (weld metal deposit).
Skrew Rolling of Balls in Multiple Helical Impressions
Authors: Tomczak J. , Pater Z. , Bartnicki J.
Published: January 2014

This paper presents results of theoretical and experimental research on skew rolling process of balls with diameter ;30 mm in multiple helical tools. Numerical analysis of the process was conducted basing on finite element method (FEM), using the commercial software Simufact Forming in version 10.0. Simulations were made in the three-dimensional state of strain with consideration of complex thermal analysis, due to which progression of the products shape was determined. Distributions of strains and temperatures as well as the process force parameters were also determined. The results of numerical calculations were experimentally verified in laboratory conditions. The obtained results confirmed the possibility of semi-finished products of balls type manufacturing by means of rolling in multiple helical impressions.
Influence of Boiler Pipe Cladding Techniques on their Microstructure and Properties
Authors: Rozmus-Górnikowska M. , Blicharski M. , Kusińsk J. , Kuslnski L. , Marszyck M.
Published: January 2014

The aim of this work was to investigate different weld overlay coating technologies applied to steel boiler pipes and their influence on microstructure and properties of the produced overlays. The investigations were carried out on the boiler pipes weld overlaid by an Inconel 625 and cladded at various conditions (CMT, GMAW and GTAW). The investigations showed that microstructure and mechanical properties of overlaid pipes depend on cladding technology and the chemical composition of the base material.
The Influence of the Shape of Turbulence Inhibitors on the Hydrodynamic Conditions Occuring in a Tundish
Authors: Merder T.
Published: January 2014

The article presents results of the research that was carried out taking into account the influence of the (impact pads) turbulence inhibitor geometry and its equipment of the working space on the hydrodynamic conditions occurring in T-type tundish. Four different turbulence inhibitors were discussed. They differ in shape and configuration of external walls. The research was conducted basing on the numerical simulations as well as on tests performed on physical water model. As a result of calculations the velocity field distribution, turbulence field and marker concentration distribution in the liquid steel for the tested geometrical variants of turbulence inhibitors were obtained. Worked out RTD curves (Residence Time Distribution) allowed to determine the kinetics of steel mixing (the range of transient zone was estimated), and the percentage participation of the particular flow zones. The test carried out on the water model concerned one of the tested turbulence inhibitors. Research was done to verify the parameter settings of the numerical model applied in calculations. Obtained results gave valuable information about the work of the object after applying different turbulence inhibitors.
Investigation of the Usability of Cubic Boron Nitride Cutting Tools as an Alternative to Diamond Cutting Tools for the Aircraft Industry
Authors: Islak S. , Kir D. , Çelik H.
Published: January 2014

Diamond and cubic boron nitride (cBN) cutting segments were produced using hot pressing technique for this study to be used in cutting natural stone. cBN grains were added to bronze powder, the chosen matrix, at a rate of 0%, 20%, 40%, 60%, 80%, and 100% (according to percentage by weight). Segments were produced under a pressure of 35 MPa, at a sintering temperature of 600°C, over a sintering time of 3 minutes. The cutting properties of the produced segments were determined by cutting Ankara andesite. A Scanning Electron Microscope (SEM) and an X-Ray Diffractometer (XRD) were used to analyse the microstructure, phase compound, and wear surfaces of each segment type.
Thermo-Mechanical Model of a TIG Welding Process for the Aircraft Industry
Authors: Hojny M.
Published: January 2014

TIG welding is the most important process, which is used in the aircraft industry. A number of components of airplane are made using this method. Thermo-mechanical models are needed to understand better phenomena involved in this process. In the presented work thermo-mechanical simulations were performed and the possibilities of welding distortion in the investigated process were evaluated. Comparison of the results of numerical simulation with the experimental data confirmed good predictive capabilities of the model and quite good description of the phenomena involved in this process.
Premature Cracking of Dies for Aluminium Alloy Die-Casting
Authors: Pawłowski B. , Bala P. , Tokarski T. , Krawczyk J.
Published: January 2014

Two identical dies for aluminium alloy die-casting failed prematurely because of a number of parallel cracks on the working surface. These cracks were of a mechanical nature related to incorrect microstructural banding orientation of the die core and related to improper heat treatment. The microstructural banding orientation was determined by metallographic examination of the specimens, which were cut from the dies along the three axes of the coordinate system. Scanning electron microscopy (SEM) examination of the fracture surfaces and along the crack path (including energy dispersive spectroscopy (EDS) analysis) indicated that the root cause of the premature cracking of the dies was improper heat treatment (quenching and tempering conditions). Additionally, resistance to fracture of the investigated specimens, as measured by the Charpy V-notch test, was five times lower than that required for the desired hardness.
Microstructure and Corrosion Resistance Characteristics of Cr-Co-Mo Alloys Designed for Prosthetic Materials
Authors: Augustyn-Pieniążek J. , Lukaszczyk A. , Zapala R.
Published: January 2014

The work presents the results of microscopic tests of two alloys: Co-Cr-Mo and Co-Cr-W-Mo, together with a quantitative local analysis of the chemical composition, with the use of an electron microprobe X-ray analyzer EDS. Corrosion resistance tests were also performed on the alloys, in the artificial saliva environment. The microstructure of the examined alloys was of the dendrite type. An eutectic consisting of alloy carbides and a cobalt austenite was observed in the interdendritic spaces. The dendritic matrix was a solid solution of chromium, molybdenum and carbon in cobalt (Co), and the precipitates present in the interdendritic spaces were rich with Cr and Mo - in the case of Co-Cr-Mo - and with W and Mo - in the case of Co-Cr-W-Mo. The analyzed materials exhibited a similar progress of polarization curves. The obtained currentless potential values and the wide passivation area of those alloys made it possible to conclude their high corrosion resistance in the examined environment.
Studies on Stress and Strain State in Cold Orbital Forging a AlMgSi Alloy Flange Pin
Authors: Samołyk G.
Published: January 2014

The orbital forging is one of the metal forming processes which enables the manufacture of products through worm or cold working. A characteristic feature of this technological process is the use of a special wobbling motion of one of the tools in order to reduce the required forming force. This is particularly advantageous during the formation of products in the shape of a disc or a flange pin. Unfortunately, typical constraints of cold orbital forging are: uncontrolled buckling, loss of shape stability (“mushroom effect”) and cracks. They depend on the technological parameters of the process and their cause can be explained on the basis of e.g. workpiece stress state analysis, which is a difficult task due to the complexity of orbital forging process. The article discusses the issues of stress and strain in cold orbital forged parts of the flange pin type, made of AlMgSi aluminum alloy. The results of the presented FEM simulation, verified experimentally, explain the influence of the theoretical aspects of this process on its implementation conditions. It is assumed that orbital forging is performed on the PXW-100A press and the numerical model takes into account all possible variants of the process. Debate boils down to discussing the stress and strain state (e.g. analyzing the stress and strain rate fields) occurring in the workpiece in the context of chosen technological parameters and constrains of orbital forging process
On the Reconstruction Method of Ceramic Foam Structures and the Methodology of Young Modulus Determination
Authors: Nowak M. , Nowak Z. , Pęcherski R.B. , Potoczek M. , Śliwa R.E.
Published: January 2014

In the present paper a finite element model was used to investigate the mechanical properties such as Young’s modulus of open-cell ceramic foam. Finite element discretization was derived from real foam specimen by computer tomography images. The generated 3D geometry of the ceramic foam was used to simulate deformation process under compression. The own numerical procedure was developed to control finite element mesh density by changing the element size. Several numerical simulations of compression test have been carried out using commercial finite element code ABAQUS. The size of the ceramic specimen and the density of finite element mesh were examined. The influence of type and size of finite element on the value of Young’s modulus was studied, as well. The obtained numerical results have been compared with the results of experimental investigations carried out by Ortega [11]. It is shown that numerical results are in close agreement with experiment. It appears also that the dependency of Young’s modulus of ceramic foam on density of finite element mesh cannot be ignored.
Mathematical Foundations of Limit Criterion for Anisotropic Materials
Authors: Ostrovvska-Maciejewska J. , Szeptyński P. , Pęcherski R.B.
Published: January 2014

In the paper a new proposition of limit state criteria for anisotropic solids exhibiting different strengths at tension and compression is presented. The proposition is based on the concept of energetically orthogonal decompositions of stress state introduced by Rychlewski. The concept of stress state dependent parameters describing the influence of certain stress modes on the total measure of material effort was firstly presented by Burzynski. The both concepts are reviewed in the paper. General formulation of a new limit criterion as well as its specification for certain elastic symmetries is given. It is compared with some of the other known limit criteria for anisotropic solids. General methodology of acquiring necessary data for the criterion specification is presented. The ideas of energetic and limit state orthogonality are discussed - their application in representation of the quadratic forms of energy and limit state criterion as a sum of square terms is shown
Fabrication of Ceramic Aggregate from Phosphogypsum and Power Plant Ash – Preliminary Studies
Authors: Sokołowski J. , Urbańska P.
Published: January 2014

The compositions of phosphogypsum and power plant ash as waste created in the production of an orthophosphoric acid and the coal combustion with the addition of fine coal were prepared. The compositions were then granulated and sintered in a muffle furnace in the atmosphere of air under the conditions previously determined. The compressive strength, open porosity and water absorption were also determined and compared with the results obtained for the commercial aggregate. Chemical and phase compositions of the aggregate were also studied. The results of the research indicate that proposed method of the high temperature utilization of phosphogypsum and power plant ash has a great potential for application and it is worth of further research.
Technology and Properties PMN-PT-PS-PFN:LI Material for Multilayer Capacitor
Authors: Niemiec P. , Skulski R. , Bochenek D. , Wawrzała P.
Published: January 2014

In this work it is designed and obtained the multicomponent material with the formula 0.6075PMN-0.2025PT-0.09PS- 0.1PFN:Li (PMN-PT-PS-PFN:Li) for applications in multilayer ceramic capacitors MLCC. Obtaining of PMN-PT-PS-PFN:Li was done by two alternative methods of synthesis. In the first method a PMN-PT-PS-PFN:Li has been obtained from simple compounds (oxides, carbonates), in the second method the complex compounds (MgNb2O6 and FeNbO4) and simple compounds (oxides PbO, TiO2 and carbonate Li2CO3) were used. From synthesized powder of PMN-PT-PS-PFN:Li the ceramic samples were obtained which have next undergone comprehensive investigations. The X-ray investigations, as well as ferroelectric, dielectric and elastic investigations have been made.
Application of Ceramic Preforms to the Manufacturing of Ceramic - Metal Composites
Authors: Jach K. , Pietrzak K. , Wajler A. , Sidorowicz A. , Brykała U.
Published: January 2014

This paper presents new solution to manufacturing Cu-Al2O3 composites with a dispersed reinforcement phase. It consists in substituting commonly used commercial alumina powder with crushed ceramic foam. Very low strength of thin-walled Al2O3 porous foams results in both their easy destruction and isolation of fragments <200 μm. The addition of the ceramic phase is 3-10 vol.%. The sintering process is performed for 30 min in a hot-press at 1050°C and 30 MPa. The aim of the presented paper is to study the effect of the volume content of the ceramic phase on the microstructure and selected physical and thermal properties of copper - alumina composites.
MINING-INDUCED SURFACE HORIZONTAL DISPLACEMENT: THE CASE OF BW PROSPER HANIEL MINE / ANALIZA PRZEMIESZCZEŃ POZIOMYCH POWIERZCHNI TERENU WYWOŁANYCH PODZIEMNĄ EKSPLOATACJĄ GÓRNICZĄ NA PRZYKŁADZIE KOPALNI BW PROSPER HANIEL
Authors: Tajduś Krzysztof
Published: January 2014

The paper presents a wide-ranged analysis of horizontal displacements in the region of underground mining exploitation. Initially, various theories pertaining to the determination of mining-induced horizontal displacement are discussed, followed by a complex study on horizontal displacements measured for a selected example region of the German coal mine BW Prosper Haniel, as well as the determination of displacement factor B.
UNIQUE PROJECT OF SINGLE-CUTTING HEAD LONGWALL SHEARER USED FOR THIN COAL SEAMS EXPLOITATION / PROJEKT JEDNOORGANOWEGO KOMBAJNU ŚCIANOWEGO O SPECJALNEJ KONSTRUKCJI PRZEZNACZONEGO DO EKSPLOATACJI POKŁADÓW CIENKICH
Authors: Bołoz Łukasz
Published: January 2014

Problem of thin hard coal seams exploitation, including chosen data related with their resources in Poland, has been discussed in the introduction of the present study. On the basis of actually operated machines the assumptions, which should be satisfied by the longwall shearer used for exploitation of thin hard coal seams, have been made. A project of such longwall shearer combined with band conveyor and mechanized longwall support, including description of the machine operation technology and analysis of possible day output achievement, have been presented.
RESULTS OF THE PROMETHEE METHOD APPLICATION IN SELECTING THE TECHNOLOGICAL SYSTEM AT THE MAJDAN III OPEN PIT MINE / WYNIKI ZASTOSOWANIA METODY PROMETHEE DO WYBORU SYSTEMU TECHNOLOGICZNEGO W KOPALNI ODKRYWKOWEJ MAJDAN III
Authors: Vujić Slobodan , Hudej Marjan , Miljanović Igor
Published: January 2014

This paper discusses the application of the PROMETHEE model and the results achieved in practice, following the example of the multi-criteria selection of the technological system at the Majdan III clay mineral raw material open pit mine of the Potisje Company, Republic of Serbia. After the introduction comments, reasons are explained for selecting the new technological system, conditions and limitations for the seven alternative solutions considered are described, mathematical foundation for the PROMETHEE method and a multi-criteria model of the problem in question are presented. The solution with the following structure was ranked first and accepted by the Company management as the best: Bucket chain excavator - Conveyor belts - Spreader (ECS), alongside a decision is made on the acquisition of machinery and system construction. The system was put into operation in 2000. The experience and the data accumulated in the previous twelve years confirm that the decision made on the application of the ECS technology was just, and the conclusion lists the benefits achieved.
VERIFICATION OF FLOTATION KINETICS MODEL FOR TRIANGULAR DISTRIBUTION OF DENSITY FUNCTION OF FLOTABILITY OF COAL PARTICLES / WERYFIKACJA MODELU KINETYKI FLOTACJI DLA TRÓJKĄTNEGO ROZKŁADU FUNKCJI GĘSTOŚCI FLOTOWALNOŚCI ZIAREN WĘGLA
Authors: Kalinowski Krystian , Kaula Roman
Published: January 2014

Parameters of flotation kinetics model with a gamma and a triangular distribution have been determined based on the batch coal flotation experiments. Analyses were carried out at different values of the intensity of aeration air. The results of example analyses are presented in tables and graphs form. It follows from the carried out study on the mathematical models of flotability coefficient distribution of particles of examined coal samples that the triangular distribution model is statistical equivalent to the gamma flotability distribution. The assumption of the triangular distribution enables determination of the density function of distribution of fraction in the industrial flotation machines. Knowledge of this function will allow better evaluation of the phenomena occurring in the process of enrichment. It may be one of the basic information used in the supervisory control system.
THE EFFECT OF TEMPERATURE GLIDE OF R407C REFRIGERANT ON THE POWER OF EVAPORATOR IN AIR REFRIGERATORS / WPŁYW POŚLIZGU TEMPERATURY CZYNNIKA CHŁODNICZEGO R407C NA MOC PAROWNIKA CHŁODZIARKI POWIETRZA
Authors: Nowak Bernard , Życzkowski Piotr
Published: January 2014

The article discusses the effect of the phenomenon of temperature glide of zeotropic refrigerants on thermal power of an evaporator in an air compression refrigerator. Zeotropic mixtures are subject to phase transitions, the process of which significantly differs from that of homogeneous refrigerants. In contrast to homogeneous refrigerants, where boiling and condensing processes take place at a constant temperature, for the zeotropic mixtures it is essential to know the vapor quality to unambiguously determine the temperature at which the evaporation process is initiated. The R407C refrigerant serves as an example to describe the method of determining the initial temperature of the evaporation process taking into account the effect of temperature glide. The developed formula (7) has been based on a proven linear course of isobars in the two-phase region (Fig. 5) and thus determining a polynomial describing their angle of inclination (8). In addition, temperature calculation formulas (9) and specific enthalpy (10) of dry saturated vapor of the R407C refrigerant have been presented as well. This approach allows to determine the temperature of the R407C refrigerant at the inlet to the evaporator without the required knowledge of its vapor quality. The previously used simplified methods for determining the temperature of a refrigerant at the inlet to the evaporator result in considerable deviations in calculated power of the evaporator compared with its actual value. The presented calculation example involving mine air compression refrigerator of TS-450P type shows that relative deviations of the evaporator thermal power may even exceed 20%. This example compares two simplified methods for determining zeotropic evaporating temperature of a refrigerant used in comparative calculations of refrigerants with the method presented in this article.
Mathematical model of a plate fin heat exchanger operating under solid oxide fuel cell working conditions
Authors: Kupecki Jakub , Badyda Krzysztof
Published: January 2014

Heat exchangers of different types find application in power systems based on solid oxide fuel cells (SOFC). Compact plate fin heat exchangers are typically found to perfectly fit systems with power output under 5 kWel. Micro-combined heat and power (micro-CHP) units with solid oxide fuel cells can exhibit high electrical and overall efficiencies, exceeding 85%, respectively. These values can be achieved only when high thermal integration of a system is assured. Selection and sizing of heat exchangers play a crucial role and should be done with caution. Moreover, performance of heat exchangers under variable operating conditions can strongly influence efficiency of the complete system. For that reason, it becomes important to develop high fidelity mathematical models allowing evaluation of heat exchangers under modified operating conditions, in high temperature regimes. Prediction of pressure and temperatures drops at the exit of cold and hot sides are important for system-level studies. Paper presents dedicated mathematical model used for evaluation of a plate fin heat exchanger, operating as a part of micro-CHP unit with solid oxide fuel cells.
Numerical analysis of CO2 capture efficiency in post combustion CCS technology in terms of varying flow conditions
Authors: Niegodajew Paweł , Asendrych Dariusz , Drobniak Stanisław
Published: January 2014

The paper deals with the computational fluid dynamics modelling of carbon dioxide capture from flue gases in the post combustioncapture method, one of the available carbon capture and storage technologies. 30% aqueous monoethanolamine solution was used as a solvent in absorption process. The complex flow system including multiphase countercurrent streams with chemical reaction and heat transfer was considered to resolve the CO2 absorption. The simulation results have shown the realistic behaviour and good consistency with experimental data. The model was employed to analyse the influence of liquid to gas ratio on CO2 capture efficiency.
ENERGY POTENTIAL IN PRODUCTION OF FAST-GROWING POPLAR CLONES IN SLOVAK REGIONS
Authors: Petráš Rudolf , Mecko Julian , Petrášová Viera
Published: January 2014

Calorific value production from the above-ground biomass of stands was derived from its volume production. The mathematical models of growth tables of I-214 and Robusta poplar clones, biomass density values and calorific values of biomass dry matter were used for its calculation. At the stands aged 35 years and site indices of 20, 30 and 40, the calorific value has approximately 2.700, 6.000 and 9.300 GJ.ha-1 respectively. The I-214 clone has higher production than Robusta in the first half of its growth, albeit with minimum differences. The annual increments of calorific value culminate about the age of 9-13 years with values of 450-115 GJ.ha-1. Mean annual production of both clones culminates at the age of 17-26 years with values of 320-80 GJ.ha-1. Lowland forest locations with high level of ground water in Slovakia with the total area of 25.600 ha are most suitable for poplars production. On this area, we can assume the mean annual production of 3.566 TJ of gross calorific value obtained from above-ground biomass in the future. From that, about 64% is in wood, 14% in bark and 22% in small-wood. Up to 85% of this production potential is situated in the area of The Danube Lowland and the rest is mainly in southern areas of the Central and Eastern Slovakia.
Effect of Temperature and Used Ingredients on Rheological Parameters of Pancake Dough
Authors: Hlaváč Peter , Božiková Monika
Published: January 2014

This paper presents the selected rheological properties of pancake dough such as dynamic and kinematic viscosity and fluidity. The effect of used ingredients and temperature on rheological properties is investigated. Measurements were performed on three pancake dough samples. In two samples, there was used milk with a different fat content, and in the third sample, all ingredients were in a powder state. A digital rotational viscometer Anton Paar DV-3P was used for measuring the rheological properties. The principle of viscometer measurement is based on the dependence of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of rheological parameters on temperature. Exponential functions were used to express the dependencies of all rheological parameters on temperature. Dynamic and kinematic viscosity decreased, and fluidity increased with temperature. The highest values of dynamic viscosity were obtained for pancake dough from powder ingredients. A higher fat content of used milk caused higher values of dynamic viscosity.
Cutting Process Capability Study
Authors: Škůrková Katarína Lestyánszka , Žarnovský Jozef
Published: January 2014

This study focuses on the evaluation of cutting process capability in the production of printed circuit boards according to regulation defined by ISO 9001: 2008 Quality Management Systems. Requirements. Therefore, statistical process control is analysed on the basis of normality and stability of the process, and cutting process capability indices Cp and Cpk are calculated. The values obtained for indices are Cp = 6.801 and Cpk = 5.499. Therefore, we can consider the process as capable.
Increasing calculation accuracy in the design stage of a gas transportation system
Authors: Neacşu Sorin , Rădulescu Renata
Published: January 2014

The paper presents a critical evaluation of the equations used to calculate the flow and pressure for transport pipelines. A highly accurate method for calculating gas parameters is proposed. The final part of the paper presents some comparisons between the proposed method and modern simulators used for the design of transport systems.
Considerations on transport capacity of natural gas pipelines and its limits
Authors: Neacşu Sorin , Suditu Silvian , Stoica Doru
Published: January 2014

The paper deals with the transport capacity of the pipeline and shows its variation in accordance with working parameters. The most drastic limitation occurs when the sonic choke is reached. This should be avoided during the operation of transport systems.
Ensuring security of local gas supply using pipeline gas storage
Authors: Eparu Cristian , Suditu Silvian , Prundurel Alina
Published: January 2014

This paper presents a natural gas supply system of a locality. Since power consumption is nonstationary, for supplying the consumption peaks it is used a gas deposit kept in a pipeline built near the locality. The viability of this solution was demonstrated by simulation with the numerical simulator SIMONE.
Preliminary studies on genetic diversity of ectomycorrhizal fungus Suillus bovinus in Lithuania
Authors: Motiejūnaitė Jurga , Kačergius Audrius , Kasparavičius Jonas
Published: January 2014

Motiejūnaitė J., Kačergius A., Kasparavičius J., 2013: Preliminary studies on genetic diversity of ectomycorrhizal fungus Suillus bovinus in Lithuania [Pradiniai ektomikorizinio grybo Suillus bovinus genetinio kintamumo Lietuvoje tyrimai]. - Bot. Lith., 19(2): 91-98. Genetic diversity of some Lithuanian populations of Suillus bovinus was assessed basing on nucleotide sequence of ITS1 and 2 regions, and the 5.8S RNA gene obtained from 42 samples. Four haplotypes were defined, each representing isolate groups of varying abundance and distribution. The most abundant and widely distributed was haplotype 2. All Lithuanian haplotypes nested in one, the largest clade of European isolates of S. bovinus.
Benthic microalgae under the influence of beach nourishment in the Gulf of Odessa (the Black Sea)
Authors: Snigirova Anastasiya
Published: January 2014

Snigirova A., 2013: Benthic microalgae under the influence of beach nourishment in the Gulf of Odessa (the Black Sea) [Paplūdimių papildymo smėliu poveikis bentosinių dumblių bendrijoms Odesos įlankoje (Juodoji jūra)]. - Bot. Lith., 19(2): 120-128. The coast of the Gulf of Odessa (Odessa Bay) in the north-western part of the Black Sea is exposed to abrasive processes, which lead to its destruction. One of the measures for landslides stabilization is sand nourishment, which was held on the beach of the gulf in October 2007. As a result of shore protection works, the sand grain size on the beaches of Odessa has decreased by 53% on average. The influence of sand grain size on the abundance and biomass of benthic microalgae was investigated. Benthic microalgae were presented mostly by Bacillariophyta and Dinophyta. Other groups of Chlorophyta, Cyanophyta and Cryptophyta were less presented. The abundance and biomass of algae increased threefold and fourfold, accordingly, as a result of sand nourishment. Significant influence of fine sand particles on the biomass and abundance of microalgae was revealed. However, the structure of algological assemblages changed because of the increase of mixotrophic groups of algae contribution.
Process Management in Public Management of a Transition Country: Case Study of Bosnia and Herzegovina
Authors: Salkić Ismet , Bošnjović Jasna
Published: January 2014

Background: New methods, means and approaches for increasing the efficiency of public administration are constantly being discovered. This paper considers the possibility of applying a new form of organisation-known as the process organisation structure-in public administration. Objectives: The first aim is to conduct research on the extent to which work processes in public administration in Bosnia and Herzegovina are process oriented. The second aim of this paper is to measure the efficiency of public administration in Bosnia and Herzegovina. Methods: The research was conducted through a questionnaire survey and included all governmental levels in Bosnia and Herzegovina. The study involved 112 public organizations' managers in Bosnia and Herzegovina. Results: The first result is that the concept of business process organization has different values depending on the level of government. Another result is that the success of public organizations is different at different governmental levels in Bosnia and Herzegovina. Conclusions: This paper shows that the process-oriented management can be applied in public administration with the result of increasing the efficiency of organisations, thus increasing citizen satisfaction with public services. This paper should encourage managers and leaders to consider applying this model in the public sector, i.e. in public administration.
Clusters as a Factor of Rural Tourism Competitiveness: Montenegro Experiences
Authors: Moric Ilija
Published: January 2014

Background: The tourism cluster-approach is considered to be an appropriate strategy in emerging economies and less developed areas. Due to scarce resources and a great number of structural problems of rural areas in Montenegro, uniting all stakeholders and attractions into a competitive tourism cluster would ensure that the area could operate and become an effective and efficient rural tourism destination. Objectives: The objective of this paper is to highlight the key challenges of rural tourism clustering and provide new data and a wider understanding of the tourism-cluster approach in Montenegrin rural areas. Methods: Using the extensive literature, available secondary data from government bodies, NGOs, foreign development agencies, relevant international organisations and primary data collected from rural tourism operators in Montenegro, the paper investigates key challenges and factors associated with (in)efficiency of Montenegrin theme trails. Results: Several management and marketing issues are identified regarding the cluster approach implementation. Special importance and significance of information technologies and intelligent systems have been recognized in sense of cost-effective marketing implementation. Most Montenegrin trails are still in the first phase of cluster development, whereas just two of them have experienced a significant improvement in cooperative behaviour. Conclusions: Key benefits of the cluster approach are noted and clearly defined, but in the case of the Montenegrin rural tourism sector, these potentials are still, to a large extent, underused.
Croatia’s participation in the Seventh Framework Programme: a Moderate Success?
Authors: Mataković Hrvoje , Novak Iva Radočaj
Published: January 2014

Background: The Framework Programme (FP7) is the main instrument of the EU for financing research, and participation in the programme benefits greatly to countries’ technological development. Objectives: The aim of this paper is to assess the participation of Croatian organisations in FP7 in terms of specific programmes, funding schemes and the coordinator organisations. Methods: In order to assess this participation, two analyses have been done: the first is the analysis of participation itself analysing the basic characteristics of Croatian participation in FP7 using participation data. The second analysis is the analysis of external conditions for participation, i.e. a framework that influenced the quantity and the quality of participation in FP7. Results: Participation of Croatian institutions in the FP7 has the following features: the positive rate of the national and the EU financial contribution; an unequal regional distribution; a small number of projects coordinated by Croatian participants; a low success rate and rare participation in large research projects. Conclusions: Support should be provided to researchers in order to increase the participation in future funding programmes. First, researchers should perform only research and not the project administration since it requires well-educated and trained administration staff. Second, participants in future projects, especially coordinators, should be financially rewarded.