bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of traffic noise for medium heavy vehicles in octave bands
Authors: Bąkowski A , Dekýš V , Radziszewski L , Świetlik P
Published: April 2020

The paper presents the analysis results of medium heavy vehicle traffic measurements which were used to simulate the noise measurands. The Cnossos-EU model were used for this purpose. The medium heavy vehicle traffic volume and velocity were recorded by permanent automatic sound and traffic monitoring station. The noise was calculated in octave bands according to the Cnossos-EU model. The results were described using parameters such as the median, average peak level – C90, average background noise level – C10, percentiles C25 and C75. Analyzes carried out for the tested section of the road showed that the traffic of medium heavy vehicles is one of the main source of road noise. It has been shown that maximum values of the equivalent sound level occur for the frequency of f0
= 1 kHz. The positional measures of traffic noise were proposed for data scattering. The dispersion of noise and type A uncertainty of the results were evaluated. It was found that in most cases, the distribution of the tested variable was not normal. It was notice a lack of symmetry between the time distribution of traffic flow of vehicles entering and leaving the city.
Mathematical model of the vehicle initial rectilinear motion during moving uphill
Authors: Bulgakov M , Shuklynov S , Uzhva A , Leontiev D , Verbitskiy V , Amelin M , Volska O
Published: April 2020

In the article the mathematical model of the vehicle motion with elastic tires, which describes the phases of the initial rectilinear motion on the longitudinal slope of the road is shown. The mathematical model is valid for vehicle with two axles, one of which is driving axel and provided that the stopped vehicle on a slope is kept from rolling only by braking the non-driving axle. The aim of the study is to determine the equations to describe the process of vehicle initial rectilinear motion during moving uphill, which take into account the tires deformation energy on the stationary vehicle braking wheels. The presented equations described in the article are reflect the dynamic state of the stationary vehicle on a slope and the phase of its initial moving off uphill after brining the engine torque through the transmission to the wheels of the drive axle. The system of equations describing the vehicle dynamic behavior after brining torque to the drive wheels takes into account their false slip. The system of equations is obtained from the general dynamic equation in the form of balance of the elementary work of external forces and moments with the absence of external slipping of the driving wheels. The mathematical model of the vehicle initial rectilinear motion on a longitudinal slope of a highway described in the article can be used in theoretical basis for analyzing and synthesizing control algorithms for automatic driver assistance systems during vehicle initial motion.
The fault tree simulation modeling
Authors: Chovanec A , Mikuš P , Breznická A
Published: April 2020

This article explains differences in mathematical and simulation modeling approaches for solving quantitative analysis of the fault tree. With basic knowledge of reliability of complex systems and priorities in determining the phenomenon of component failure that is critical to system failure. It brings a look at fault tree solution based on statistical view and using simulation modeling with variable time step and graphical representation of events.
Topology Optimization of B-pillar with Respect to Mesh Type and Size
Authors: Chval Z , Raz K , Almeida Aguiar Ícaro
Published: April 2020

This paper deals with the influence of different mesh types and element sizes in topology optimization. Meshes from brick elements, tetrahedral elements and combination of both of them were compared in sizes 20, 10 and 7mm. B-Pillar, structural car component, is used here in order to verify the sensitivity of topology optimization due to these changes. Loading case is considering side force 140 kN. Moreover, different solvers implemented in Siemens NX 12 (RAMP, LINEAR, LATTICE and SIMP) were used to analyse how they influence this particular optimization process. It is obvious that highest number of FEM elements is rapidly improving convergence and optimization results but computational time is increasing.
3D simulations of solidification with liquid phase flow
Authors: Gawronska E , Dyja R
Published: April 2020

The work discusses issues related to 3D coagulation simulations including liquid phase flow. The approach chosen by the authors is based on the numerical solution of the enthalpy solidification formula and the Navier-Stokes equation, in which the buoyancy force approximation was added. Both of these equations are discretized in space using Finite Element Method, and in both cases time integration utilizes the Theta scheme, which is a generalized form of Euler Backward approach. The presence of the Navier-Stokes equation in the model forces the use of special techniques to ensure the convergence of the solution. From a number of available methods, the method of adding stabilizing elements in the FEM formulation was chosen, i.e. the stabilization formulas PSPG/SUPG (Pressure Stabilized Petrov Galerkin/Streamline Upwind Stabilized Petrov Galerkin). The occurrence of large temperature gradients, however, made it necessary to use the so-called lumped mass matrix in the energy equation. The work presents the results obtained using a model implemented by the authors in the form of a computer program written in C++ programming language. The use of this language and appropriate libraries made it possible to obtain sufficient performance to perform 3D solidification simulations.
FEM analysis of selected construction bodies of the conceptual bike
Authors: Konecki K , Talaśka K , Kołodziej A
Published: April 2020

The main subject of work is a concept bike featuring a non-standard construction. The classic frame has been replaced with a straight beam. Consequently, there is a much greater stress on some of the components of the bike body. Furthermore, the construction of these body components becomes more complex which calls for the employment of the numerical method of stress calculation. The work involved carrying out a strength analysis for several selected components of the bike body utilizing the finite element method (FEM). The primary object of analysis was the wheel rotation mechanism. The result of the analysis allows to develop an optimized construction, allowing to select the most suitable materials and to determine the appropriate and compact dimensions.
Research of vehicle control informative functioning capacity
Authors: Kuric I , Gorobchenko O , Litikova O , Gritsuk I , Mateichyk V , Bulgakov M , Klackova I
Published: April 2020

Harmful influence of human factor upon industrial processes and while vehicles running control necessitates to search for ways of its minimizing or total elimination. During the trials of ergatic system “locomotive team – brigade” assessment of informative functioning capacity of machinist is done with experimentally-statistic method. According to the research done the total number of signals that influence on locomotive brigade in process of movement makes approximately 20000 for during one trip, and the number of signals indicating abnormal situation reaches 165 for one trip. In time of train movement the period of signal processing lays at such interval – 0.3c < toc < 11c. It was stated during calculations with given assumptions that informative functioning capacity of a locomotive brigade approaches the threshold values, which constitute 2–4 bps. Received model allows to evaluate parameters of informative functioning capacity on a locomotive brigade in contrast to the information which should be obtained by a machinist in process of taking management decisions. This enables to define the ways of a locomotive brigade informative functioning capacity decrease.
Tightness of flange joints: A case study
Authors: Lošák P , Létal T , Naď M , Pernica M
Published: April 2020

One of the negative technological factors that often have a significant impact on the environment is the leakage of operating media (so-called fugitive emissions), which most often occurs at different separable joints. Therefore, high demands are placed on the joints – they must have sufficient strength to maintain pressure and other loads and also be tight enough to avoid undesired leaks. For a large part of such joints, standard flanges or flanges designed according to standards are used, in the European Union in particular according to EN 1092-1, EN 1591-1 and EN 13445-3. Although the strength of such flanges is sufficient for most applications, the basic design methods do not cover the tightness of flange joints and their emissions completely. A case inspired by industrial practice with a history of insufficient tightness resulting in leaks is investigated using FEA and EN 1591. The flange joint is modelled in software ANSYS 2019 R2 with parts of adjacent shells to take their effect into account. The goal of the analyses is estimation of gasket contact pressures resulting from load history. The pressures are directly related to the seal tightness. Lastly, effect of shell shape modification on the gasket pressures is also investigated and the results are compared with those from the original configuration. Effects of resulting pressures on seal tightness are discussed.
Computation of temperature field by cell method and comparing with commercial software
Authors: Pernica M , Létal T , Lošák P , Naď M
Published: April 2020

This paper deals with the temperature field of the shell and tube heat exchanger with segmental baffles. Two different types of shell and tube heat exchangers were analysed by a numerical model for thermal-hydraulic rating called the cell method. The cell method is a numerical computational model for calculating of temperature field of a shell and tube heat exchanger with segmental baffles. A huge benefit of the cell method is especially its simplicity. The computation of temperature field by the cell method is very fast and without the necessity of powerful hardware accessories. For analyses, two different types of shell and tube heat exchangers with segmental baffles were used. First, a co-current flow heat exchanger with a floating head and second a counter-current flow heat exchanger with a fixed tubesheet. Both analysed heat exchangers are horizontal, have one tube and one shell pass and segmental baffles. The results from cell method were compared with results from the commercial software for thermal-hydraulic rating HTRI, which is one of the most widely used commercial software for solving thermal-hydraulic rating of heat exchangers. The scope of this paper is to assess how exact the cell method is and if its results are useful for a mechanical design of shell and tube heat exchanger with segmental baffles.
Simulation of child passenger collision in the rail vehicle interior
Authors: Špirk S , Vychytil J
Published: April 2020

Passive safety of rail vehicles is described by two documents. These requirements for structural crashworthiness are covered by EN 15227 standard. The GMRT 2100 standard (currently mandatory in UK) summarizes the requirements for interior safety. The actual legislation deals only with an injury of an average adult male (50 percentile). An assessment of interior passive safety for the wider population (5 and 95 percentile) will be other logical steps (in the near future). This approach is well known from automotive industry. This study identifies the most dangerous factors for child passenger collisions in the interior of a rail vehicle. Virtual simulations, finite element method and multibody simulations are used for that. It is possible to overtake the current trends and to carry out a rail interior safety assessment for children due to the excellent scalability of the VIRTHUMAN model. The data of the vehicle design were obtained from the local producers. The vehicles which are used in this research were developed recently and they are generally used. The injury criteria are used for probability of injury evaluation. Some first recommendations for rail interior design safe for children are provided at the end of this paper.
The design issues of rolling bearing assemblies
Authors: Talaśka K , Wojtkowiak D , Fierek A
Published: April 2020

The design of rolling bearing assemblies, e.g.: shaft bearings, calls for specialized engineering knowledge. The problem requires synthetic knowledge of machine design and construction as well as knowledge of bearing manufacturer specifications. Mounting bearings on shafts and in housings requires to maintain correct dimensional deviation. The actual condition of the roller surface of the external shaft pin and the external housing has a material influence on the working efficiency and durability of the bearing. The development of examination tools to determine the stress condition of pin/housing as well as bearing rings after installation is of great importance, as well as determining shape faults of specific type and deviations of particular value. The paper presents numerical analyses which allow to determine the state of stress in the contact area of the assembly components: pin/housing-bearing rinds. The study was performed for selected shape faults, selected bearings and specific deviation values.
Numerical analysis of thermal phenomena during surface heat treatment of AlZn5.5MgCu aluminum alloy by GTA welding method
Authors: Winczek J , Iwaszko J , Matuszewski M
Published: April 2020

In work, the modelling of a three-dimensional temperature field during surface modification of AlZn5.5MgCu aluminum alloy using GTAW (Gas Tungsten Arc Welding) technology is presented. GTAW is widely used for making welded joints using additional material (filler material). In the analyzed process, no additional material was used, and the effect of heat treatment was obtained by directly applying the electric arc to the surface of the material. The calculations were performed using Finite Element Method. The Goldak’s double ellipsoidal heat source model has been used in modelling. The thermal-mechanical properties of the material were assumed to depend on the temperature. The Workbench, DesignModeler, Mechanical, Fluent and CFD-Post modules of the ANSYS program were used for numerical simulations. In the description of the geometry of element heat treated, cube type elements were used, with density of grid in the heat affected zone. The temperature distributions in cross-sections of heated element as well as welding thermal cycles at selected points were analyzed. The results of numerical simulations were verified experimentally. Comparison of calculated and obtained in the experiment the fusion lines showed satisfactory compatibility.
Numerical study of linearization techniques for Bouc-Wen hysteresis model considering random inputs
Authors: Sága M , Vaško M , Ságová Z , Handrik M , Kopas P , Jakubovičová L , Muravev V V , Muraveva O V
Published: April 2020

Our study focuses on the numerical solution of the stochastic vibration of elastic-plastic mechanical systems with Gaussian random excitations. It’s realized the short review about linearization techniques in stochastic dynamics mainly with application in area of elastic-plastic finite element modelling using BW (Bouc-Wen) differential mathematical model. The presented methods of statistical linearization, Hurtado-Barbat’s modification of statistical linearization, statistical quadratization and Monte Carlo approach are applied to numerical testing.
Synthesis and sensitivity analysis of the crank-rocker mechanism
Authors: Sapietová A , Štalmach O , Sapieta M
Published: April 2020

Based on the theoretical background, this paper presents a design of a crank-rocker mechanism, which is also known as extreme case of the four-bar linkage. This is very common mechanism used for stone crushing in the practice. Initial functional design is performed by the method of geometric synthesis in combination with analytical calculations. The most common problem associated with the synthesis of the crank-rocker mechanism is that of designing the linkage for a given oscillation angle and a given time ratio. To improve the efficiency of the device is performed the sensitivity analysis in the MSC.ADAMS with the goal to refine the designed geometric parameters.
Methods for measuring the position of the centre of gravity of an anthropotechnic human-wheelchair system in dynamic conditions
Authors: Wieczorek B , Kukla M , Warguła Ł
Published: April 2020

The article presents the methods for measuring the position of the centre of gravity of an anthropotechnic human-wheelchair system in dynamic conditions. The methods were verified by the pilot studies using a pushrim-propelled wheelchair. Data processing methods were used to fit the ellipses to measured datasets including 4.463 to 3.434 points, where the ellipses are defined by their centres M C.G., inclinations α and semi-axes a and b. The method involves defining each ellipse fit to the dataset with a likelihood of inclusion of new position points of the centre of gravity. The ellipses characterized by the highest likelihood were selected, which for the tested cases was between 29.7 % to 40.9 %, depending on the test.
The problem of fixing the axisymmetric elements on the example of pulley mounting on the shaft
Authors: Domek G , Kołodziej A , Dziubek I
Published: April 2020

The paper present the problem of permanent fixing of the axisymmetric elements relative position on the example of pulley mounting on the shaft. A method of permanent and quick fixing of pulleys on shafts has been sought for years. A number of detachable and inseparable joint solutions are available. The authors are looking for an inseparable solution allowing for quick assembly in serial production conditions. The quality of this connection is important for the geometry of the transmission gear, as it has a significant impact on the quality of the transmission gear operation and the belt life.
The influence of the limit stress value on the sublimation rate during the dry ice densification process
Authors: Górecki J , Fierek A , Talaśka K , Wałęsa K
Published: April 2020

The article presents the results of research on the influence of limit stress of the densification process on sublimation of dry ice during the forming process in piston technology. The research concerns the process of agglomeration of waste material in fragmented form, obtained as a result of the crystallization process of liquid carbon dioxide. The material is characterized by low temperature and sublimation under ambient conditions. During the research, the focus was on determining the influence of the limit value of densification stress on the value of the material efficiency factor of the process. In previous studies, it was observed that the weight of the product in the form of pellets is significantly smaller than the fragmented dry ice dispensed to the densification chamber. In order to improve the efficiency of the process, tests were carried out to determine the characteristics describing its change in function of the limit value of the densification stress.
Analysis of residual stresses on guide bar of chainsaw
Authors: Kostka J , Čarák P , Frankovský P , Adamuščin M
Published: April 2020

Problematics of residual stresses is known in engineering practice, but it is often forgotten. They are present in each component. Residual stresses can be introduced into the material not only during the manufacturing process, but also when the equipment is used. Every machine system a special approach to its application during operation. In case of non-compliance with its boundary conditions failure can comply damage of components, which may even lead to complete deterioration of the equipment. The aim of the paper is to point out how improper use of equipment affects residual stresses that can lead to its damage. The most used method for determining residual stresses was used – hole drilling method. The practical part deals with the specific application of the hole drilling method on the selected component – the chainsaw guide bar. The next part of the theses is followed by an evaluation of the results and proposal of solution that will contribute to more efficient use of the given structural element and its lifetime.
The impact of wheelchairs driving support systems on the rolling resistance coefficient
Authors: Warguła Ł , Kukla M , Wieczorek B
Published: April 2020

The 21stcentury is characterized by an increase in the obesity of society, including people with disabilities. The increase in the weight of people in wheelchairs requires them to have more power to drive these types of vehicles. Diseases and a varied level of disability or infirmity may lead to the inability to overcome the resistance of a vehicle driven by muscle power, such as a wheelchair. The solution to this problem are systems supporting the motion of this type of vehicles among which we can distinguish electric-manual hybrid drives that add energy to the drive system and systems that reduce the amount of force necessary for the movement of the cart lowering at the same time of its moving speed. Systems and mechanisms that have been developed for this purpose contain an increased number of cooperating elements than in a classic wheelchair, leading to an increase in rolling resistance. The article presents the methodology and test results of rolling resistance coefficients of wheelchairs with innovative systems supporting their propulsion showing that the tested auxiliary drives generate an increase in rolling resistance of vehicles for the disabled from 30 % to 75 %.
Comparison of experimental flexural test with FE analysis for specimen with different size and shape of internal structure created by 3D printing’s
Authors: Dorčiak F , Vaško M , Bárnik F , Majko J
Published: April 2020

The aim of the paper was to compare experimentally measured values and bending test simulations. Specimens was created by 3D printing. Material for specimens is composite Onyx. The samples were different in the internal structure. The inner structure has a different shape and size. Flexural test measured stress from the force required to bend a beam under three points loading conditions. Aim this paper was to find out the data, which will used to select choice size and shape of the inner structure dimensions for parts that will loads with flexing. By optimizing the size and shape of the inner structure to ensure the choice of the right structure for a given issue with regard to material consumption. The samples are sized according to ISO 178. The test was carried out according to ASTM D790 and next ISO 178. Test measured the force required to bend the specimen he test is stopped when the specimen reaches 5 % deflection or the specimen breaks before 5 %. If the sample can withstand the desired deflection, the test will continue by norm ISO 178 and the test is stopped when the specimen breaks. The same was simulated in Ansys workbench using the FEM calculation method. These data processed in tables and graphs and mutually compared with boundary values. The lower limit or value will be a hollow sample. The upper limit was a solid sample where the highest stiffness is expected.
Modeling selected mechanical properties of magnetorheological elastomers
Authors: Kukla M
Published: April 2020

Magnetorheological elastomers are an important group of non-classical engineering materials. The aim of the works carried out is to study the influence of magnetic field on a series of mechanical properties of composite materials in this group. Based on prior analyses, a limited usability of the viscoelastic material model was identified for the purpose of describing the stress-strain relationship in magnetorheological elastomers. Therefore, it has become necessary to propose changes to this rheological model. The present article includes theoretical considerations in relation to the mathematical derivation of functions allowing to account for the influence of strain amplitude on the progressive character of the mechanical hysteresis loops in the materials under discussion. It also provides a detailed analysis of the derived formulas together with a discussion, supplemented with the description of employed simplifying assumptions.
FE modeling of continuous fiber reinforced thermoplastic composite structures produced by additive manufacturing
Authors: Majko J , Sága M , Vaško M , Handrik M , Ságová Z
Published: April 2020

Additive manufacturing is process of joining material, bringing many benefits such as customization and low production cost. Markforged developed Continuous fiber fabrication technology, which allows to print continuous fiber reinforced thermoplastic (CFRTP) composites. Although printed CFRTP parts achieve mechanical properties better than another 3D printed counterparts, there is demand to gain suitable mechanical properties comparable with conventionally manufactured parts using improvements in printing parameters and fiber deposition. In this paper, the main goal is analyzing of geometry constraints of fiber deposition and modeling options in FEM program ADINA. Additionally, stress distribution analysis with regard to stresses in matrix and fibers will be performed.
Elastomer modification by means of ionizing radiation
Authors: Bobrova V , Kasperovich A , Mozyrev A , Krmela J , Krmelová V
Published: April 2020

One of the priorities for improving the performance characteristics of elastomer compositions is their physical modification, which allows to obtain materials with a new set of performance properties. Among the known methods of modifying products based on elastomers, one of the actual methods is radiation modification. It allows you to control the physico-mechanical and elastic-strength characteristics of products. In connection with the foregoing, the development of a technology for the radiation modification of elastomers with the aim of increasing their operational characteristics is relevant. In this work, the effect of ionizing radiation on the thermo-physical and operational properties of elastomeric compositions for the tread of career tires was investigated. It was established that the level of the maximum temperature developed in the samples depends on the degree of vulcanization of the elastomeric compositions. In samples of tread rubber, heat generation is reduced by 2–4 % after treatment with accelerated electrons. In the process of exposure to ionizing radiation, the formation of free radicals and their subsequent recombination occurs. Revealed an increase in crosslinking density in modified specimens. The correlation dependences between the thermophysical properties of elastomeric compositions and the intensity of heat generation in them are established. It was determined that the best thermo-physical properties of polymers with a degree of crosslinking t80. The wear resistance of the modified elastomeric compositions is increased up to 3.5 times.
Influence of mounting on hanging bolt lifetime
Authors: Dubec A , Kováčiková P , Janeková M
Published: April 2020

The main objective of this article is analysis of the hanging bolt failure that forms part of the weight transfer device. The base material of this bolt was protected by a surface layer to prevent corrosive influence of the environment. This bolt was used in combination with another screw of the same type to fix the movement of the device in the horizontal direction. This device operates by means of a hydraulic circuit at the rear of the agricultural machine and performs a vertical axis movement. The fracture surfaces of the bolt failure were evaluated on a thermo-emission scanning electron microscope. In the next part of the experiment, the micro-purity and microstructure of the material of the damaged hanging bolt was evaluated by optical microscopy. The main benefit of this article is the study of hanging bolt failure depending on the mounting design condition and from the way of its loading. Knowledge from this research is important to ensure safety with handling and protecting heavy loads from damage.
The impact of DCSBD plasma discharge on polypropylene
Authors: Janík R , Kohutiar M , Pajtášová M , Dubec A , Pagáčová J , Šulcová J
Published: April 2020

The diffuse coplanar surface barrier plasma discharge (DCSBD) still belongs to specific methods of modifying (activating) the surface of polymeric materials. The present work deals with surface treatment of polypropylene foils by plasma discharge, investigation and subsequent identification of changes caused by mentioned discharge. The modified surface was examined by measuring the wetting angle. Film surface morphology and topography was investigated by scanning electron microscope (SEM) and atomic force microscopy (AFM), respectively. Subsequently, it was examined whether the modification of polypropylene by DCSBD plasma discharge only affects the surface of the investigated material or also changes structural properties in studied material, based on the obtained data from DMA analysis.
The threaded part wear of the tensioner with lock nut
Authors: Kováčiková P , Dubec A , Koštialiková D
Published: April 2020

The tensioner with lock nut is an important part of the timing mechanism, which is often used in motorized engines. This component consists of a plurality of parts which are connected to each other by a threaded part. The threaded part of the tensioner serves to precisely adjust the position of its front part against the timing chain. This setting ensures the correct position of the guide part and thus the running of the motorcycle engine. The benefit of this research is the analysis of changes on the threaded part surface, which is important for correct working of the tensioner it is necessary that the threaded part fulfill its purpose. It is necessary to prevent its degradation or excessive wear. Scanning electron microscopy and energy dispersive spectroscopy methods were used to determine the wear of the threaded part of the tensioner. The evaluation focused on surface changes in the threaded part and the possible occurrence of foreign particles on the surface with respect to their material contrast and chemical composition.
Structure and properties of nucleated polypropylene fibres
Authors: Krmelová V , Gavendová M , Zatroch T , Krmela J , Dubec A , Bizubová B , Kleščík M , Balogová A
Published: April 2020

This work is focused on the evaluation of the structure and properties of the nucleated polypropylene (PP) fibres prepared by melt spinning technique at lower take-up velocities as pre-oriented fibres (POY) containing 0.3–1.5 wt. % of additives - nucleating agents like 1,3:2,4-dibenzylidene sorbitol (DBS), quinacridone (QA) and calcium carbonate (CC). The thermal properties of nucleated PP fibres were determined by using differential scanning calorimetry (DSC). Used additives promote nucleation activity, DBS and QA better than CC, as they increased the crystallization temperature to higher extent than CC. Effect of CC seems to be negligible, due to very little impact on melting point and crystallization temperature. Morphological characteristic of the PP fibres were observed by means of scanning electron microscopy. The morphology of nucleated PP is different significantly from that of reference non-nucleated PP fibre. The measured values of the above mentioned properties were compared with parameters of non-nucleated PP fibre prepared under same technological conditions.
Application of alternative additives in the polymer composite systems used in automotive industry
Authors: Ondrušová D , Labaj I , Vršková J , Pajtášová M , Zvoláneková Mezencevová V
Published: April 2020

The paper deals with the application of alternative waste-based fillers from industry into two various types of polymer composite systems used in the automotive industry. The first type of alternative filler (GW) was obtained by treating the waste from the glass production. It was applied to the multi-component polymer matrix consisting of phenolic and melamine resin and nitrile rubber commonly used in the friction composite system for clutch facing production. Another type of alternative filler (EG) has been obtained from energetics where it is produced as a by-product of flue gas desulfurization. This type of filler was mixed into elastomeric composite system for tire production as a substitution of commonly used carbon black filler. The specific surface area of various fractions of alternative fillers used was determined and the influences of this fillers parameter on the rheology and vulcanization characteristics, as well as physical and mechanical properties of two types of newly prepared polymer systems have been investigated.
The influence of corrosion of TiO2 films on their surface properties
Authors: Pagáčová J , Papučová I , Šulcová J , Plško A
Published: April 2020

The work deals with the influence of TiO2 films corrosion in distilled water on the surface properties of TiO2 films. Films were prepared from the sol in “Ti(i-PrO)4 - IPA - H2O - HNO3” system by dip-coating technique. The surface properties of films were observed using atomic force microscopy and sessile drop method. The morphology and rms-roughness of prepared films were evaluated. On the basis of Fowkes method, the contact angles of films, using distilled water and diiodomethane, were used for determination of surface free energy and its polar and dispersion components. The given surface properties of TiO2 films were compared from the aspect of their preparation temperature (200, 300 and 400 °C) as well as corrosion in water. It was observed, that the film preparation temperature did not have noticeable influence on studied surface properties for non-corroded films. The influence of corrosion was observed only for films prepared at temperature of 300 °C and 400 °C. The corrosion in water influenced the morphology of film surface, increased the roughness, contact angle for water as well as the value of dispersion component of surface free energy.
The influence of corrosion of inorganic-organic films on their surface properties
Authors: Papučová I , Pagáčová J , Plško A
Published: April 2020

The work deals with the influence of water corrosion on the surface properties of inorganic-organic SiO2 films, which were prepared from the sols in “tetraethoxysilane-isopropyl alcohol-water-nitric acid-triethoxy(octyl)silane” system. The atomic force microscopy and sessile drop technique was used on the characterization of surface properties. The morphology, rms-roughness, adhesion force and stiffness of prepared films were evaluated. Surface free energy and its polar and dispersion component were calculated by Owens-Wendt method using contact angles of distilled water and diiodomethane. The influence of corrosion on all of the studied properties of films was significant in the case of films prepared from sol with molar ratio of x(H2O) : x(SiO2) = 2.
Surface properties of non-black fillers
Authors: Skalková P , Dubec A , Pagáčová J , Krmela J , Martinec J
Published: April 2020

This work was focused on characterization of surface properties of various types of silica used for elastomers. The influence of temperature and length of degassing on the resulting specific surface of silica was studied. Eight types of precipitated and pyrogenic silica samples were investigated in terms of surface characteristics as specific surface, porosity and morphology that directly affects these properties. For characterization was performed using sorption methods, scanning electron microscopy and IR spectroscopy. From the results of the analyzes it was found that the properties of precipitated and pyrogenic silica differ significantly in terms of particle size, structure, porosity and size of specific surfaces. The degassing temperature and time largely influence the behavior of nitrogen adsorption and hence the measurement results.
Glass surface modification using diffusion coplanar surface barrier discharge (DCSBD)
Authors: Šulcová J , Papučová I , Janík R
Published: April 2020

The paper deals with the surface modification of the glass substrates using diffuse coplanar surface barrier discharge (DCSBD). The changes of surface properties after modification with plasma discharge were observed in time. During eight days, contact angles were measured by the method of sessile drop, using distilled water and diiodomethane as testing liquids. The surface free energy and its polar and dispersion component were calculated using Fowkes method. The morphology and rms-roughness of modificated substrates were evaluated, using atomic force microscopy. The effect of modification by plasma discharge on the observed surface properties is the most noticeable immediately after modification. After 3 days, the observed surface properties of the modified surface are comparable to the unmodified surface.
Pre-clinical testing of different implant structures in animal subjects
Authors: Mitrík L , Trebuňová M , Hudák R , Schnitzer M , Živčák J
Published: April 2020

The aim of this study was to develop a methodology of preclinical animal testing in case studies for implants with PEEK material and its derivatives with possible use for other materials. In the theoretical part, the study deals with the analysis of the current situation in the area of preclinical animal testing, especially in the field of implantology. Based on this analysis, the test implant structures were prepared at the workplace, which were subsequently inserted into appropriate rabbit individuals by surgical intervention in case studies. These case studies serve to create a comprehensive test methodology for animal preclinical tests within a statistically relevant animal sample for the needs of subsequent clinical testing and certification of the biomaterial used. These studies confirmed that the proportion of ceramic admixture elements in PEEK promoted the growth of bone tissue.
Influence of aberrations and roughness on the chromatic confocal signal based on experiments and wave-optical modeling
Authors: Claus Daniel , Nizami Moaaz Rauf
Published: April 2020

This paper addresses the effect and influence of wave optical aberrations and surface roughness on the chromatic confocal signal and resulting measurement errors. Two possible approaches exist for implementing chromatic confocal imaging based on either refraction or diffraction. Both concepts are compared and an expression for the expected chromatic longitudinal aberrations when using a diffractive optical element is derived. Since most chromatic confocal sensors are point sensors, the discussion on wave-optical aberrations is focused on spherical aberrations. Against common belief, the effect of spherical aberrations cannot be eliminated in the calibration process using for instance a piezo mounted mirror. It will be shown in the following that even a diffraction limited system with peak to valley spherical aberration smaller than 0.25 wavelength suffers from measurement errors. Experimental results will be shown to highlight this important issue. In order to develop a deeper understanding of the underlying physics, a wave-optical simulation environment has been realized. This wave-optical model furthermore enables the investigation of the influence of roughness. Herethereto the correct choice of numerical aperture when investigating a rough surface is based on a heuristic approach. Using the wave-optical simulations an explanation for the increased noise when employing a low numerical aperture to examine rough surfaces will be derived. Furthermore, a formula is presented to support the selection of the correct numerical aperture with regards to the roughness parameters of the surface under investigation.
Observation of nm-thin spinterface-like structures in few walled carbon nanotubes by pyrolysis of sulfur/ferrocene mixtures
Authors: Odunmbaku O , Taallah A , Sameera I , Wang S , Boi F S
Published: April 2020

The observation of rehybridized monolayer interfacial phases between graphene-like systems and monoatomic metal phases (spin-interfaces or spinterfaces) has recently attracted significant attention. Spinterface materials result from chemical interaction between a graphene-based material and the chosen ferromagnetic metal at the atomic level. Despite the significant amount of research, controlled observation of spinterface inside carbon nanotubes (CNTs) has been elusive. Recent works have however reported evidence of monoatomic-iron- diffusion within the graphene walls of CNTs produced by pyrolysis of ferrocene/sulfur mixtures. In this work we demonstrate that formation of these interfacial nm-thin Fe-based superstructures is observable only when certain critical quantities of sulfur are pyrolyzed in a ferrocene vapour (i.e. 2.5 mg to 4 mg). For lower quantities of this precursor (0.4 mg) or with vapour flow rates higher than 11 ml min−1 no spinterface-nucleation could be probed. By employing complementary TEM, HRTEM, STEM and XPS methods we suggest that the concentration of sulfur can play a critical role in allowing the uniform nucleation of spinterface structures inside CNTs.
Near term carbon tax policy in the US Economy: limits to deep decarbonization
Authors: Roth Michael Buchdahl , Adams Peter J , Jaramillo Paulina , Muller Nicholas Z
Published: April 2020

This paper explores carbon dioxide (CO2) tax policies from 2015 to 2030 in the United States economy using an energy system least-cost optimization model. We report limited near-term decarbonization opportunities outside of the electricity sector, which results in substantial CO2 tax revenue through 2030. Second, because the social cost of carbon is uncertain, we find asymmetric deadweight loss from implementing mistakenly high or low CO2 taxes, providing efficiency-based support for the precautionary principle. Third, despite CO2 reductions occurring mainly in the electric sector, the abatement estimated herein is consistent with the US nationally determined contributions established under the Paris Agreement.
Faecal microbiota transplantation as a home therapy to frail older people
Authors: Jørgensen Simon Mark Dahl , Rubak Tone Maria Mørck , Damsgaard Else Marie , Dahlerup Jens Frederik , Hvas Christian Lodberg
Published: April 2020

Background

Clostridioides (Clostridium) difficile infection (CDI) is a leading cause of antibiotics-associated diarrhoea. Faecal microbiota transplantation (FMT) is effective for recurrent CDI and may be provided as a home treatment to frail, older people.

Methods

We present four consecutive patients with recurrent CDI, treated at home using nasojejunal tube-delivered or encapsulated donor faeces. The primary outcome was combined clinical resolution and a negative CD toxin test 8 weeks post-treatment.

Results

All four patients had severe CDI and all improved clinically following one FMT. Sustained resolution following one FMT was observed in one patient. Two patients had recurrence and received a second FMT using capsules; both achieved resolution. One patient who had recurrence declined from further FMT due to fear of relapse and was established on long-term vancomycin. No adverse events related to FMT were observed.

Conclusion

Frail older people may benefit from FMT. Home treatment is a viable option and may be considered both for clinical cure and for palliation.
Urbanization is associated with increased breeding rate, but decreased breeding success, in an urban population of near-threatened African Crowned Eagles
Authors: Muller Rebecca , Amar Arjun , Sumasgutner Petra , McPherson Shane C , Downs Colleen T
Published: April 2020

Urban areas can be attractive to certain species because of increased food abundance and nesting availability, which in turn may increase productivity or breeding rates. However, there are also potential costs associated with urban living such as higher nest failure, poorer body condition, or increased prevalence of disease. These costs may result in species trading off the number of young produced against the condition of their young. African Crowned Eagles (Stephanoaetus coronatus) are a rare example of large, powerful apex predators that breed in some urban areas in Africa. In this study, we explored the breeding performance of these eagles across an urbanization gradient in KwaZulu-Natal Province, South Africa, over 7 breeding seasons. We predicted that living in an urban environment would increase productivity through an increase in breeding rate (shifting from typically biennial breeding to annual breeding). We then explored if there were any hidden costs associated with such a change in breeding strategy by examining the body condition of chicks from pairs that had successfully bred in the previous year. We found that pairs in more urban areas were more likely to breed annually, resulting in higher breeding rates, but were also less likely to successfully fledge a chick (i.e. lower breeding success). These 2 contrasting responses counteracted each other and resulted in similar productivity across the urbanization gradient. For those eagles that bred in consecutive years, annual breeding did not appear to have a negative cost on chick condition. The switch to annual breeding is thought to be a response to improved or more constant food sources in urban areas, while higher failure rates might be because of increased nest disturbances from anthropogenic sources (e.g., vegetation clearing, development of industrial areas, human and car traffic). However, although urbanization negatively affected the breeding success of African Crowned Eagles, they are able to persist and thrive in this highly transformed environment, likely through an increased breeding rate.
Education, Training, Case, and Cause: A Descriptive Study of School Social Work
Authors: Forenza Brad , Eckhardt Betsy
Published: April 2020

School social workers (SSWs) play a vital role in district-level education, but ambiguity within our collective understanding of school social work is a pervasive problem. Clarity of the SSW role is important for communities of place (schools), practice (SSWs), and circumstance (consumers of school social work). This research recruited and surveyed 52 SSWs in a focal state to contextualize their practice domains and professional capacity. Findings broadly pertain to the actual and idealized education and training of SSWs, as well as their case-level and cause/system-level job functions. The article concludes with a discussion of the implications for policy, practice, and future research.
Evaluation of an Urban School-Based Social, Emotional, and Behavioral Health Professional Development and Consultation Model
Authors: Kaye Amy J , Pejic Vanja , Jordan Molly , Dennery Kristine M , DeMaso David R
Published: April 2020

Social, emotional, and behavioral health challenges pose significant barriers to students’ academic success, yet teachers report that they do not feel equipped with the knowledge and skills needed to address these challenges in their classrooms. This article presents findings associated with the effectiveness of an innovative school-based behavioral health professional development and consultation model designed to address this need for urban educators. Program evaluation results from school-based team members from five pilot schools over a two-year partnership period indicate that this model is highly used and valued by school staff, as well as perceived by school staff as effective in building the knowledge, skills, and self-efficacy to implement strategies and build systems in schools to address students’ social, emotional, and behavioral health needs. Progress monitoring data suggests that this learning is translating to actual systemic change in schools based on school-based team members’ reports of progress toward goals specific to the behavioral health systems, procedures, and protocols at their schools. The findings highlight the implications for school-based consultants and practitioners based on the promise of this model.