bluuebunny/crossref_metadata_2025 huggingface dataset:
Lewatit S100 in Drinking Water Treatment for Ammonia Removal
Authors: El-Hady H. M. Abd , Grünwald A. , Vlčková K. , Zeithammerová J.
Published: March 2021

Ammonium nitrogen is the most important form of nitrogen that can cause excessive algal growth and stimulate eutrophication in surface water. The purpose of this study is to investigate the possibility of removing ammonium from drinking water by means of an ion Exchange process. Polymeric Lewatit S100 material (particle-size 0.3–1.2 mm) was used. The breakthrough capacity was determined by dynamic laboratory investigations and the concentration of regenerant solution (5 and 10 % NaCl) was investigated. The concentration of ammonium ion inputs in the tap water that we used were 10, 5 and 2 mg NH4+ l_1 and down to levels below 0.5 mg NH4 + l_1. The experimental results show that the breakthrough capacity was very small at ammonium concentration 2 mg NH4 + l_1 compared to its breakthrough capacity at ammonium concentration 10 mg NH4 + l_1. There was no difference between regeneration by 10 and 5 % NaCl. We conclude that the use of Lewatit S100 is an attractive and promising method for ammonium concentration greater than 5 mg NH4 + l_1 and till 10 mg NH4 + l_1 .
Clinoptilolite in Drinking Water Treatment for Ammonia Removal
Authors: El-Hady H. M. Abd , Grünwald A. , Vlčková K. , Zeithammerová J.
Published: March 2021

In most countries today the removal of ammonium ions from drinking water has become almost a necessity. The natural zeolite clinoptiloliteis mined commercially in many parts of the world. It is a selective exchanger for the ammonium cation, and this has prompted its use in water treatment, wastewater treatment, swimming pools and fish farming. The work described in this paper provides dynamic data on cation exchange processes in clinoptilolite involving the NH4 +, Ca+2 and Mg+2 cations. We used material of natural origin – clinoptilolite from Nižný Hrabovec in Slovakia (particle-size 3–5 mm). The breakthrough capacity was determined by dynamic laboratory investigations, and we investigated the influence of thermal pretreatment of clinoptilolite and the concentration of regenerant solution (2, 5, and 10% NaCl). The concentrations of ammonium ion inputs in the tap water that we used were 10, 5, and 2 mg NH4 + l_1 and down to levels below 0.5 mg NH4 + l_1. The experimental results show that repeated pretreatment sufficiently improves the zeolite’s properties, and the structure of clinoptilolite remains unchanged during the loading and regeneration cycles. Ammonium removal capacities were increased by approximately 40 % and 20 % for heat-treated zeolite samples. There was no difference between the regenerates for 10% and 5% NaCl. We conclude that the use of zeolite is an attractive and promising method for ammonium removal.
Nonlinear Continuous System Identification by Means of Multiple Integration II
Authors: John J.
Published: March 2021

This paper presents a new modification of the multiple integration method [1, 2, 3] for continuous nonlinear SISO system identification from measured input - output data. The model structure is changed compared with [1]. This change enables more sophisticated systems to be identified. The resulting MATLAB program is available in [4]. As was stated in [1], there is no need to reach a steady state of the identified system. The algorithm also automatically filters the measured data with respect to low frequency drifts and offsets, and offers the user a potent tool for selecting the frequency range of validity of the obtained model.
Filling and Recycling Apparatus of a Cyclotron Target with Enriched Krypton for Production of Radiopharmaceuticals
Authors: Vognar M. , Fišer M. , Šimáně Č. , Chvátil D.
Published: March 2021

An apparatus for multiple filling of a cyclotron target with enriched Kr gas is described. The system is based on recycling pressurized gas by cryogenic pumping between the target tube and storage containers. The design and construction makes use of previous experience in the construction and operation of two analogue apparatuses for Xe124 high pressure gas targets, but major modifications have been incorporated, evoked by the different physical properties of Kr, by the character of the nuclear reaction, and by the demand for automation from the side of the end user.
Some Problems of the Integration of Heat Pump Technology into a System of Combined Heat and Electricity Production
Authors: Böszörményi G. , Böszörményi L.
Published: March 2021

The closure of a part of the municipal combined heat and power (CHP) plant of Košice city would result in the loss of 200 MW thermal output within a realtively short period of time. The long term development plan for the Košice district heating system concentrates on solving this problem. Taking into account the extremely high (90 %) dependence of Slovakia on imported energy sources and the desirability of reducing the emission of pollutantst the alternative of supplying of 100 MW thermal output from geothermal sources is attractive. However the indices of economic efficiency for this alternative are unsatisfactory. Cogeneration of electricity and heat in a CHP plant, the most efficient way of supplying heat to Košice at the present time. If as planned, geothermal heat is fed directly into the district heating network the efficiency would be greatly reduced. An excellent solution of this problem would be a new conception, preferring the utilization of geothermal heat in support of a combined electricity and heat production process. The efficiency of geothermal energy utilization could be increased through a special heat pump. This paper deals with several aspects of the design of a heat pump to be integrated into the system of the CHP plant.
Comparison Between Atmospheric Turbidity Coefficients of Desert and Temperate Climates
Authors: Elminir Hamdy K. , Rahuma U. A. , Benda V.
Published: March 2021

Knowledge of the solar radiation available on the earth’s surface is essential for the development of solar energy devices and for estimating of their performance efficiencies. For this purpose it is helpful to study the attenuation of direct normal irradiance by the atmosphere, in terms of fundamental quantities, including optical thickness, relative optical air mass, water vapor content, and aerosol amount. In the present article, we will not deal with cloudy atmospheres because of their great variability in space and time, but will focus our attention on atmospheres characterized by the complete absence of condensed water. The objectives of this article are to report data on aerosol optical depth and atmospheric turbidity coefficients for a desert climate, and to compare them with those of a temperate climate. Aerosol optical depth, the Linke turbidity factor, TL, and ngström turbidity coefficients, _, are calculated from measurements of broadband filters at Helwan, Egypt, which has a desert climate. A linear regression model is to be determined between the Linke factor and the ngström turbidity coefficient. This relation is compared with similar relations reported for a temperate climate [Prague, Czech Republic]. This comparison is made to determine whether a universal relation exists between these two important coefficients, or whether the relation is location dependent.
Accuracy of Determining Stress Intensity Factors in Some Numerical Programs
Authors: Vorel M. , Leidich E.
Published: March 2021

At present, there are many programs for numerical analysis of cracks, in particular for determining stress intensity factors. Analyses of a single-edge cracked beam and flat plate with a semielliptical surface crack are presented in this study to examine the accuracy and applicability of the Franc2d and Franc3d programs. Further numerical computations of the MARC program and analytical solutions of stress intensity factors were included to compare the results with each other. For this purpose MARC was equipped with special user procedures. The influence of mesh fineness on the results was also investigated in all programs. The distributions of the stress intensity factors show good agreement in quality. The maximum deviations from the analytical solutions are 9.7 %. With greater numbers of elements programs Franc2d and Franc3d showed some instability, which currently reduces the usefulness and reliability of these promising tools for engineering applications.
Investigation into Airborne Dust ina Wool Textile Mill
Authors: Haghi A. K.
Published: March 2021

Airborne dust samples were gathered from the vicinity of various commonly performed processes in the wool-preparation industry. Samples of airborne wool dust were collected on membrane filters during the processing of wool lots. The chemical composition of the inorganic particles present in the total inspirable and respirable dust fractions was determined with the use of a Scanning Electron Microscope (SEM). The widely differing morphologies of the particles collected raise questions about the validity of trying to correlate minor respiratory symptoms with dust concentrations, as some particle types will penetrate the respiratory system more easily than others. The results are discussed with respect to the sampling methodology used.
Analysis of a Thermal Plasma Diamond CVD System
Authors: Kolman D.
Published: March 2021

This paper deals with the analysis of a typical engineering system utilizing thermal plasma - a system for Diamond Chemical Vapor Deposition. It defines the system - a slightly overexpanded plasma jet impinging at a downstream -located substrate, outlines the theoretical description of the system - the Navier-Stokes and species conservation equations, and presents key theoretical results on the major and most troublesome factors influencing diamond deposition - velocity and temperature of the jet. Then, the paper demostrates the necessity to shift from a laminar to a turbulent flow description and compares both results to experiments. An explanation of the remaining discrepancy - insufficient velocity drop in the jet - is attempted.
Power Characteristics of a Screw Agitator in a Tube
Authors: Rieger F.
Published: March 2021

Screw agitators rotating in tubes are very efficient tools for mixing and pumping viscous liquids. The power characteristic of the agitator-tube assembly must be known to enable its power consumption in a given configuration to be calculated. The dimensionless power characteristic is described by Eq. (6). An estimate of power consumption from the power characteristic is schematically shown in Fig. 1. The dependence of the coefficients in Eq. (6) on the Reynolds number is shown in Fig. 5. The power characteristics for selected Reynolds number values are shown in Figs. 6- 9.
A Geothermal Energy Supported Gas-steam Cogeneration Unit as a Possible Replacement for the Old Part of a Municipal CHP Plant (TEKO)
Authors: Böszörményi L. , Böszörményi G.
Published: March 2021

The need for more intensive utilization of local renewable energy sources is indisputable. Under the current economic circumstances their competitiveness in comparison with fossil fuels is rather low, if we do not take into account environmental considerations. Integrating geothermal sources into combined heat and power production in a municipal CHP plant would be an excellent solution to this problem. This concept could lead to an innovative type of power plant - a gas-steam cycle based, geothermal energy supported cogeneration unit.
Parasitic Events in Envelope Analysis
Authors: Doubek J. , Kreidl M.
Published: March 2021

Envelope analysis allows fast fault location of individual gearboxes and parts of bearings by repetition frequency determination of the mechanical catch of an amplitude-modulated signal. Systematic faults arise when using envelope analysis on a signal with strong changes. The source of these events is the range of function definition of used in convolution integral definition. This integral is used for Hilbert image calculation of analyzed signal. Overshoots (almost similar to Gibbs events on a synthetic signal using the Fourier series) are result from these faults. Overshoots are caused by parasitic spectral lines in the frequency domain, which can produce faulty diagnostic analysis.This paper describes systematic arising during faults rising by signal numerical calculation using envelope analysis with Hilbert transform. It goes on to offer a mathematical analysis of these systematic faults.
Education for Production and Operations Management
Authors: Kavan M.
Published: March 2021

The Department of Mechanical Engineering Enterprise Management at the Faculty of Mechanical Engineering of the Czech Technical University in Prague has its own doctoral programme, and runs postgraduate and master's courses. The Department is engaged in a great deal of research in the field of marketing, financial and mainly operations management. A new Production and Operations Management programme was started in 1997. The programme consists of: Management of Change and the Importance of Innovations, Forecasting and Operations Strategy, Design of Work Systems, Total Quality Management and Inventory Control, Material Requirements Planning and Just-In-Time Systems, Logistics and Practical exercises. The study programme is organised in two stages, winter and summer semesters. The study programme has a strong international orientation. The teaching goal is to prepare students for dealing with real-world settings and implementing the most effective up-to-date practices. The Department aspires to lead in research, and in developing modern concepts and tools. Research is being conducted in the mechanical engineering industry under a grant from the EU LEONARDO programme. We invite you to email with questions or to schedule a visit to the Department at any time.
Optimization of the Odor Microclimate
Authors: Jokl M. V.
Published: March 2021

The odor microclimate is formed by gaseous airborne components perceived either as an unpleasant smell or as a pleasant smell. Smells enter the building interior partly from outdoors (exhaust fumes - flower fragrance) and partly from indoors (building materials, smoking cigarettes - cosmetics, dishes). They affect the human organism through the olfactory center which is connected to the part of brain that is responsible for controlling people's emotions and sexual feelings: smells therefore participate to a high level in mood formation. Sweet smells have a positive impact on human feelings and on human performance. Criteria for odor microclimate appraisal are presented together with ways of improving the odor microclimate (by stopping odors from spreading within a building, ventilation, air filtration, odor removal by plants, deodorization, etc.), including so-called AIR DESIGN.
Modelling of Deterioration Effects on Concrete Structures
Authors: Teplý B.
Published: March 2021

In order to predict the service life of concrete structures models for deterioration effects are needed. This paper has the form of a survey, listing and describing such analytical models, namely carbonation of concrete, ingress of chlorides, corrosion of reinforcing steel and prestressing tendons. The probabilistic approach is applied.
Reliability Analysis of a Steel Frame
Authors: Sýkora M.
Published: March 2021

A steel frame with haunches is designed according to Eurocodes. The frame is exposed to self-weight, snow, and wind actions. Lateral-torsional buckling appears to represent the most critical criterion, which is considered as a basis for the limit state function. In the reliability analysis, the probabilistic models proposed by the Joint Committee for Structural Safety (JCSS) are used for basic variables. The uncertainty model coefficients take into account the inaccuracy of the resistance model for the haunched girder and the inaccuracy of the action effect model. The time invariant reliability analysis is based on Turkstra's rule for combinations of snow and wind actions. The time variant analysis describes snow and wind actions by jump processes with intermittencies. Assuming a 50-year lifetime, the obtained values of the reliability index b vary within the range from 3.95 up to 5.56. The cross-profile IPE 330 designed according to Eurocodes seems to be adequate. It appears that the time invariant reliability analysis based on Turkstra's rule provides considerably lower values of b than those obtained by the time variant analysis.
New Phase Shifting Algorithms Insensitive to Linear Phase Shift Errors
Authors: Novák J.
Published: March 2021

This article describes and analyses multistep algorithms for evaluating of the wave field phase in interferometric measurements using the phase shifting technique. New phase shifting algorithms are proposed, with a constant but arbitrary phase shift between captured frames of the intensity of the interference field. The phase evaluation process then does not depend on linear phase shift errors. A big advantage of the described algorithms is their ability to determine the phase shift value at every point of the detector plane. A detailed analysis of these algorithms with respect to main factors that affect interferometric measurements is then carried out. The dependency of these algorithms on phase shift values is also studied several phase calculation algorithms are proposed. These are compared with respect to the resulting phase errors.
Prospects for Geothermal Energy Conversion through a Hybrid Combined Cycle Power Plant
Authors: Böszörményi L. , Böszörményi G.
Published: March 2021

The demand for more intensive utilization of energy sources is getting more important with the forthcoming European Union membership of the Slovak Republic. Lack of resources and poor exploitaition of available resources can be a very difficult problem for energy policy. It is important to use technical solutions to minimize or eliminate this problem. The most beneficial progress could be achieved in the Košice basin where geothermal energy could have effective and multi-purpose use.
An Algorithm for Investigating the Structure of Material Surfaces
Authors: Toman M. , Procházka P.
Published: March 2021

The aim of this paper is to summarize the algorithm and the experience that have been achieved in the investigation of grain structure of surfaces of certain materials, particularly from samples of gold. The main parts of the algorithm to be discussed are:1. acquisition of input data,2. localization of grain region,3. representation of grain size,4. representation of outputs (postprocessing).
A Simulation Study for Computing the Emissivity of Clouds
Authors: Seker S. , Aydemir M. E. , Apaydin G.
Published: March 2021

In this study, propagation through various distributions of lossy particles in clouds is investigated. Clouds may contain several types of crystal forms which can be modelled in the physical optics scattering region such as thin long cylinders and flat plate. The bistatic scattering patterns and emissivities of various types of clouds are computed for waves of selected polarizations passing through clouds with specified sizes, shapes and distributions. The results are in good agreement with the literature.
A General Approach to Study the Reliability of Complex Systems
Authors: Repici G. M. , Sorniotti A.
Published: March 2021

In recent years new complex systems have been developed in the automotive field to increase safety and comfort. These systems integrate hardware and software to guarantee the best results in vehicle handling and make products competitive on the market.However, the increase in technical details and the utilization and integration of these complicated systems require a high level of dynamic control system reliability. In order to improve this fundamental characteristic methods can be extracted from methods used in the aeronautical field to deal with reliability and these can be integrated into one simplified method for application in the automotive field.Firstly, as a case study, we decided to analyse VDC (the Vehicle Dynamics Control system) by defining a possible approach to reliability techniques. A VDC Fault Tree Analysis represents the first step in this activity: FTA enables us to recognize the critical components in all possible working conditions of a car, including cranking, during 'key-on'-'key-off ' phases, which is particularly critical for the electrical on-board system (because of voltage reduction).By associating FA (Functional Analysis) and FTA results with a good FFA (Functional Failure Analysis), it is possible to define the best architecture for the general system to achieve the aim of a high reliability structure.The paper will show some preliminary results from the application of this methodology, taken from various typical handling conditions from well established test procedures for vehicles.
GIS, Information Technology and Spatial Planning
Authors: Maier K.
Published: March 2021

Geographic information systems have been introduced local and regional planning several stages. They have influenced the technique of planning but only to a lesser extent the procedures of planning and the methodology of plan-making. More recently, information technology has challenged the whole concept of planning as an expert-and-government interplay. However, legal frameworks have not reflected the substantial change in the potentials of the technology.Any effort to reflect the new technology will face not only institutional inertia but increasingly also the human capacity of users of planning (i.e., decision-makers, administrators, stakeholders), namely the limited extent of overall IT literacy, which restricts the possible benefits of the technology. The dimension of access to and empowerment in planning may reappear in the context of new technologies, with new professional requirements for planners, beyond the computer, GIS and information technology.
The Biomechanics of Gender Difference and Whiplash Injury: Designing Safer Car Seats for Women
Authors: Mordaka J. , Gentle R.
Published: March 2021

Female car users are reported to have a higher incidence of soft tissue neck injuries in low speed rear-end collisions than males, and they apparently take longer to recover. This paper addresses the whiplash problem by developing a biomechanical FEM (Finite Element Method) model of the 50th and the 5th percentile female cervical spines, based on the earlier published male model created at the Nottingham Trent University. This model relies on grafting a detailed biomechanical model of the neck and head onto a standard HYBRID III dummy model. The overall philosophy of the investigation was to see if females responded essentially as scaled down males from the perspective of rear end collisions. It was found that detailed responses varied significantly with gender and it became clear that females cannot be modelled as scaled-down males, thus confirming the need for separate male and female biomechanical models and a revision of car test programmes and regulations which are currently based on the average male. Further investigation is needed to quantify the gender differences and then recommendations can be made for changes to the design of car seats and head restraints in order to reduce the risk of soft tissue injury to women.
Design Evaluation: Decomposition and State-space Analysis
Authors: Green G.
Published: March 2021

This paper outlines the increasing demands upon evaluation activity during the engineering design process. In particular, the need to address large numbers of innovative concept options during the conceptual design phase is stressed and a six-step methodology proposed. This methodology combines and integrates techniques of inexact reasoning with the need to combine two basic human approaches to evaluation, namely decomposition and holistic. The holistic evaluation elements comprise fuzzy estimates of probability of achieving Pareto optimal status combined with state-space analysis. An example demonstrates how these methods may converge to provide an appropriate support for human evaluation of emerging designs. It is concluded that the six-step methodology exhibits validity and time reduction in terms of providing an aid to the evaluation of a large number of merging designs and their associated design characteristics.
Numerical Calculation of Electric Fields in Housing Spaces Due to Electromagnetic Radiation from Antennas for Mobile Communication
Authors: Geromiller H.-P. , Farschtschi A.
Published: March 2021

The influence of electromagnetic radiation from mobile antennas on humans is under discussion in va'rious groups ofscientists, This paper deals with the impact ofelectromagnetic radiation in a housing space. The space is assumedto be bordered by 5 walls of ferroconcrete and a door-window combination on the 6th side, the latter to be electromagnetically transparent. The transparent side of the housing is exposed to an electromagnetic wave. As the source ofradiation is considered to be far away from the housing, the radiation is regarded to be from a plane wave. Due to the high signal frequency and ferroconcrete walls, 5 sides ofthe housing space are considered to be perfect conductors. The electric field inside the housing is calculated numerically by the method of finite differences for different angles of incidence of the radiated electromagnetic wave. The maximum value of the calculated electric field is outlined in a diagram.
The System for Control and Stabilization of the Beam Position in the Microtron MT-25 in Prague
Authors: Šimáně Č. , Vognar M. , Chvátil D.
Published: March 2021

A method of control the beam position at crucial points of the transport system and for the stabilization of its output position has been proposed and preliminary tested. The method is based on secondary electron emission from a thin metallic wire probe induced by electrons from the 25 MeV microtron. It was demonstrated, that magnetic field of the order of 0.2 T and parallel to the wire probe in front of the orifice of the extraction channel in the acceleration space, does not prevent the functioning of the method. A strong parasitic effect of secondary electron emission from the material of the channel and its support construction was found, leading to the inversion of the electron current polarity from the wire. This effect can be to great extent eliminated by negative electric potential bias relative to the channel. At the electron output current of 1 mA the secondary emission current from the wire probe of 0.3 mm diameter is of the order of several nA. Two electromechanical systems were designed for the removal of the probes from the beam path, to avoid the deterioration of the electron beam quality by scattering. Electronic schemes used for remote measurement of small probe currents, suppressing the influence of strong electromagnetic noise, are described. For stabilization of the output beam position two wire probes situated in air close to the Al output window were used. These probes having been placed at the periphery of the beam did not deteriorate the beam quality. The difference of their emission currents was used as an error signal to control the magnetic field of the last dipole, which kept the beam in the center of the output window.
Biological Systems Thinking for Control Engineering Design
Authors: Murray-Smith D. J.
Published: March 2021

Artificial neural networks and genetic algorithms are often quoted in discussions about the contribution of biological systems thinking to engineering design. This paper reviews work on the neuromuscular system, a field in which biological systems thinking could make specific contributions to the development and design of automatic control systems for mechatronics and robotics applications. The paper suggests some specific areas in which a better understanding of this biological control system could be expected to contribute to control engineering design methods in the future. Particular emphasis is given to the nonlinear nature of elements within the neuromuscular system and to processes of neural signal processing, sensing and system adaptivity. Aspects of the biological system that are of particular significance for engineering control systems include sensor fusion, sensor redundancy and parallelism, together with advanced forms of signal processing for adaptive and learning control.
The Effect of Pedestrian Traffic on the Dynamic Behavior of Footbridges
Authors: Studničková M.
Published: March 2021

The dynamic response of a footbridge depends namely on the natural frequencies of the structure in vertical, in horizontal and in torsion. If any of the frequencies in vertical is in the range 1.0 Hz to 3.0 Hz, the dynamic response from moving people can be significant. In this case it is necessary to calculate vibrations taking into account both serviceability and ultimate limit states. The same problem arises when any of the frequencies in horizontal (transversal) or in torsion are in the range 0.5 Hz to 1.5 Hz. Such frequencies haveare found namely in footbridges with larger spans or cable-stayed and suspension footbridges.A unique cable-stayed footbridge with prestressed concrete was dynamically analyzed and the dynamic response to simulated pedestrian loading was calculated. The calculated effects were compared with the pedestrian comfort criteria for serviceability limit states. These criteria are defined in terms of maximum acceptable acceleration of the bridge deck.
Speech Signal Recovery in Communication Networks
Authors: Zagursky V. , Riekstinsh A.
Published: March 2021

Interpolation approaches to the shape recovery of a speech signal in transmission over packet switched communications networks are proposed. The samples of signal fragments are mixed and transmitted in correspondence with standard procedure for packet-switched transmission. After reception a reverse permutation is made. In the case of packet losses missing samples are separated by several samples of the source signal. Correlation properties of the signal are used for the recovery samples due to first- and second-order non-adaptive and adaptive interpolation. For the loss of 25 % packets and second order adaptive interpolation a 2- 4 % error distribution range has been achieved.
Recycling and Networking
Authors: Bányai T.
Published: March 2021

In recent years, the notion that for environmental and legislative reasons improvements The national environmental policies and practice, including recycling strategies, are desirable and in many cases might be economically beneficial has been gaining ground. Although according to recent surveys the state of the environment in Hungary is in line with average values of the European Union, the main challenge for the country is to achieve sustainability in economic, environmental and technological terms. With a view to accession to the European Union, a harmonisation strategy must be worked out and implemented. This harmonisation strategy includes not only legislative aspects, but also social, technological, financial and logistic considerations.Because of the high logistic costs of achieving closed loop recycling systems, the author focuses on logistic aspects and tasks of the improvement phases and concentrates on the possibilities of networking and co-operation. The paper describes some possible alternative solutions for co-operative recycling processes, to improve the following logistic parameters: delivery times, accuracy of supply, running times, utilization of capacities, stock quantities, flexibility, transparency of the system, high forwarding capability, quality of product. The logistic aspects of co-operation will be analysed from the viewpoint of a closed loop economy.
Analysis of Unsteady Transonic Flow Fields by Means of the Colour Streak Schlieren Method
Authors: Ulrych J.
Published: March 2021

This article deals with a new approach to the investigation of unsteady transonic flow fields around aerodynamic models and in blade cascades using a schlieren method of flow visualisation. The principle and the application of the Colour Streak Schlieren Method (CSSM) are defined. The characteristic flow field features were observed and analysed around an oscillating NACA 0012 airfoil under the conditions of transonic free stream Mach number (M∞ = 0.9), initial angle of attack (α = +4 deg), one amplitude of oscillation (Δα=±3 deg), and three frequencies of model oscillation (f = 1, 15, 30 Hz). There is a description of the terminal shock wave hysteresis across the investigated area, which was revealed in particular cases. Application possibilities of CSSM and its further development are discussed.
Integration of CFD Methods into Concurrent Design of Internal Combustion Engine
Authors: Polášek M. , Macek J. , Vítek O. , Kozel K.
Published: March 2021

This paper describes patterns of algorithms for different innovative levels of design at parametric, configuration and conceptual levels. They can be applied to Computer-aided Engine Design (CED). Data structures, process simulation hierarchy, engine simulation modules and the requirements for further development are described. An example of advanced thermodynamics modeling of combustion engines is included.
An Integrated Decision Making Model for Evaluation of Concept Design
Authors: Green G. , Mamtani G.
Published: March 2021

The Conceptual design phase generates various design concepts and these are then evaluated in order to identify the 'Best’ concept. Identifying the Best concept is important because much of the product life cycle cost is decided in this phase. Various evaluation techniques are performed so as to aid decision-making. Different criteria are weighted against concepts for the comparison. This paper describes the research being carried out at the University of Glasgow on design evaluation. It presents the Application of fuzzy logic for design evaluation and proposes an integrated decision-making model for design evaluation. This is a part of research project that aims at developing a computer tool for evaluation process to aid decision-making.
Multifractal Image Analysis of Electrostatic Surface Microdischarges
Authors: Ficker T.
Published: March 2021

The multifractal image analysis of Lichtenberg figures has confirrmed a self- similar arrangement of surface streamers belonging to the special case of electrostatic separation discharges propagating along a surface of polymeric dielectrics.
Triangulation of 3D Surfaces Recovered from STL Grids
Authors: Rypl D. , Bittnar Z.
Published: March 2021

In the present paper, an algorithm for the discretization of parametric 3D surfaces has been extended to the family of discrete surfaces represented by stereolithography (STL) grids. The STL file format, developed for the rapid prototyping industry, is an attractive alternative to surface representation in solid modeling. Initially, a boundary representation is constructed from the STL file using feature recognition. Then a smooth surface is recovered over the original STL grid using an interpolating subdivision procedure. Finally, the reconstructed surface is subjected to the triangulation accomplished using the advancing front technique operating directly on the surface. The capability of the proposed methodology is illustrated on an example.
Mohr-Coulomb Failure Condition and the Direct Shear Test Revisited
Authors: Řeřicha P.
Published: March 2021

An alternative critical plane orientation is proposed in the Mohr-Coulomb failure criterion for soils with an extreme property. Parameter identification from the direct shear test is extended to incude the lateral normal stress.
A Simplified Analysis of the Post-buckling Behavior of a Compressed Reinforcing Bar
Authors: Kabele P.
Published: March 2021

Recently, a computational methodology based on a sequential multiscale approach, which facilitates numerical simulation of an R/C building demolition has been developed. In this type of analysis, it is necessary to capture the behavior of compressed reinforcement bars until complete rupture, which occurs due to extensive bending in the post-buckling regime. To this end, a simplified analytical model of the post-buckling behavior of a compressed bar is proposed. The simplification consists namely in considering rigid-plastic material behavior, neglecting axial contraction of the central line, and approximating the shape of the deformed central line in the plastic hinges by a circular arch. Consequently, the axial loading force, bar end displacement, and extreme strain can be expressed in relatively simple closed forms. The results obtained with the proposed model show very close agreement with those obtained by a detailed and realistic finite element analysis, which justifies the use of the simplifying assumptions.
Schema Management for Data Integration: A Short Survey
Authors: Almarimi A. , Pokorný J.
Published: March 2021

Schema management is a basic problem in many database application domains such as data integration systems. Users need to access and manipulate data from several databases. In this context, in order to integrate data from distributed heterogeneous database sources, data integration systems demand the resolution of several issues that arise in managing schemas. In this paper, we present a brief survey of the problem of schema matching which is used for solving problems of schema integration processing. Moreover, we propose a technique for integrating and querying distributed heterogeneous XML schemas.
Vibration Damping of a New Ionic Liquid under Electric Field Effect
Authors: Bicak M. M. A. , Belek H. T. , Göksenli A.
Published: March 2021

Ionic liquids are recently-developed smart materials that are not well known by mechanical engineers. They are of great interest due to their non-volatility, viscosity and extremely high electrical conductivity. Up to now, no reports have appeared on their rheological properties under magnetic or electrical fields. In this work, we study the electro-rheological behaviour of a newly presented ionic liquid (2-hydroxyethylammonium formate). Our experiments show that the ionic liquid is not sensitive to magnetic fields. Nevertheless, resonably high damping ratios (42.8%) have been attained under relatively low electric fields (0.6 kVcm-1).
Sliding Mode Implementation of an Attitude Command Flight Control System for a Helicopter in Hover
Authors: McGeoch D. J. , McGookin E. W. , Houston S. S.
Published: March 2021

This paper presents an investigation into the design of a flight control system, using a decoupled non-linear sliding mode control structure, designed using a linearised, 9th order representation of the dynamics of a PUMA helicopter in hover. The controllers are then tested upon a higher order, non-linear helicopter model, called RASCAL. This design approach is used for attitude command flight control implementation and the control performance is assessed in the terms of handling qualities through the Aeronautical Design Standards for Rotorcraft (ADS-33). In this context a linearised approximation of the helicopter system is used to design an SMC control scheme. These controllers have been found to yield a system that satisfies the Level 1 handling qualities set out by ADS-33.
Primary Response Assessment Method for Concept Design of Monotonous Thin-Walled Structures
Authors: Zanic V. , Prebeg P.
Published: March 2021

A concept design methodology for monotonous, tapered thin-walled structures (wing/fuselage/ship/bridge) is presented including modules for: model generation; loads; primary (longitudinal) and secondary (transverse) strength calculations; structural feasibility (buckling/fatigue/ultimate strength criteria); design optimization modules based on ES/GA/FFE; graphics. A method for primary strength calculation is presented in detail. It provides the dominant response field for design feasibility assessment. Bending and torsion of the structure are modelled with the accuracy required for concept design. A ‘2.5D-FEM’ model is developed by coupling a 1D-FEM model along the ‘monotonity’ axis and a 2D-FEM model(s) transverse to it. The shear flow and stiffness characteristics of the cross-section for bending and pure/restrained torsion are given, based upon the warping field of the cross-section. Examples: aircraft wing and ship hull.
Non-Standard Numeration Systems
Authors: Ambrož P.
Published: March 2021

We study some properties of non-standard numeration systems with an irrational base ß >1, based on the so-called beta-expansions of real numbers [1]. We discuss two important properties of these systems, namely the Finiteness property, stating whether the set of finite expansions in a given system forms a ring, and then the problem of fractional digits arising under arithmetic operations with integers in a given system. Then we introduce another way of irrational representation of numbers, slightly different from classical beta-expansions. Here we restrict ourselves to one irrational base – the golden mean ? – and we study the Finiteness property again.
Personal Dosimetry Enhancement for Underground Workplaces
Authors: Thinová L. , Fronka A. , Milka D.
Published: March 2021

Personal dosimetry for underground workers mainly concerns measurement of the concentration of radon (and its daughters) and the correct application of the data in dose calculation, using a biokinetic model for lung dosimetry. A conservative approach for estimating the potential dose in caves (or underground) is based on solid state alpha track detector measurements. The obtained dataset is converted into an annual effective dose in agreement with the ICRP recommendations using the “cave factor”, the value of which depends on the spectrum of aerosol particles, or on the proportional representation of the unattached and the attached fraction and on the equilibrium factor. The main difference between apartments and caves is the absence of aerosol sources, high humidity, low ventilation rate and the uneven surface in caves. A more precisely determined dose value would have a significant impact on radon remedies or on restricting the time workers stay underground. In order to determine  how the effective dose is calculated, it is necessary to divide these areas into distinct categories by the following measuring procedures: continual radon measurement (to capture the differences in EERC between working hours and night-time, and also between daily and seasonal radon concentration variations); regular measurements of radon and its daughters to estimate the equilibrium factor and the presence of 218Po; regular indoor air flow measurements to study the location of the radon supply and its transfer among individual areas of the cave; natural radioactive element content evaluation in subsoils and in water inside/outside, a study of the radon sources in the cave; aerosol particle-size spectrum measurements to determine the free fraction; monitoring the behaviour of guides and workers to record the actual time spent in the cave, in relation to the continuously monitored levels of Rn concentration.
Generic Platform for Failure Recovery in Survivable Trees
Authors: Dynda V.
Published: March 2021

Failure recovery is a fundamental task of the dependable systems needed to achieve fault-tolerant communications, smooth operation of system components and a comfortable user interface. Tree topologies are fragile, yet they are quite popular structures in computer systems. The term survivable tree denotes the capability of the tree network to deliver messages even in the presence of failures. In this paper, we analyze the characteristics of large-scale overlay survivable trees and identify the requirements for general-purpose failure recovery mechanisms in such an environment. We outline a generic failure recovery platform for preplanned tree restoration which meets those requirements, and we focus primarily on its completeness and correctness properties. The platform is based on bypass rings and it uses a bypass routing algorithm to ensure completeness, and specialized leader election to guarantee correctness. The platform supports multiple, on-line and on-the-fly recovery, provides an optional level of fault-tolerance, protection selectivity and optimization capability. It is independent of the the protected tree type (regarding traffic direction, number of sources, etc.) and forms a basis for application-specific fragment reconnection.
On Deterministic Chaos in Microdischarge Phenomena
Authors: Ficker T.
Published: March 2021

Time series of pulsating microdischarges were analysed. The results showed that deterministic chaos is present in these series. The estimated values of the correlation coefficients indicated a strong chaotic discharge behaviour.
Hilfsschulpädagogik im Krieg: Übungsschulen für Kopfschussverletzte 1914 bis 1918
Authors: Hoffmann Thomas
Published: March 2021

Thomas Hoffmann geht in seinem Beitrag von der These aus, dass der hirnverletzte Soldat im Ersten Weltkrieg eine ähnliche »Schwellenfigur« zwischen Normalität und Anormalität verkörpert, wie das Hilfsschulkind zu Beginn des 20. Jahrhunderts und dass deren gemeinsamer Bezugspunkt eine bestimmte Normvorstellung von Entwicklung ist, die diese beiden auf den ersten Blick höchst unterschiedlichen Figuren miteinander konvergieren lässt. Erst vor diesem Hintergrund wird nachvollziehbar, warum die Hilfsschulpädagogik bei der Rehabilitation der Kopfschussverletzten im Ersten Weltkrieg eine so zentrale Rolle spielte und wie in diesem Zusammenhang das Verhältnis von Pädagogik, Medizin und Psychologie begründet wurde.
Blinde Zugänge zur Vergangenheit?
Authors: Krause Susan
Published: March 2021

Wenn Vergangenheit vielfältig vergegenwärtigt werden soll, kann es sehr entscheidend sein, Personen zu Wort kommen zu lassen, die bisher nicht nach ihrer individuellen Vergangenheitsvergegenwärtigung befragt wurden. Eine solche Gruppe stellen Blinde dar. Innerhalb der bisherigen Herangehensweise an blindes, historisches Lernen, wird Blindheit häufig als Mangel charakterisiert. Zur »Überwindung« dieses Problems wird überwiegend auf Methoden zur Unterrichtsadaptation und auf Hinweise für eine gelingende Barrierefreiheit verwiesen. Im Beitrag werden darüber hinaus Betrachtungsweisen vorgestellt wie Blindheit im Kontext historischen Lernens alternativ (und als gewinnbringend) gedacht werden kann. Dabei wird auf Erkenntnisse aus den Disability Studies zurückgegriffen.
Historisches Lernen im Förderschwerpunkt geistige Entwicklung - Sinnbildung über die eigene Biografie?
Authors: Rein Franziska
Published: March 2021

Franziska Rein widmet sich unter inklusiven Gesichtspunkten in diesem Beitrag der Frage, welche Rolle die eigene Biografie für die geschichtsdidaktische Theorie spielen könnte. Exemplarisch geht sie auf biografische Sinnkonstruktionen einer Schülerin ein, die im Förderschwerpunkt geistige Entwicklung beschult wird. Die persönlichen Sinnzuweisungen dieser Schülerin beziehen sich auf Erfahrungen aus der eigenen Lebensgeschichte und ließen sich mit Hilfe der Repertory Grid Methodik, einem teilstrukturierten Interviewverfahren, gewinnen. Vorgestellt werden ausgewählte geschichtsdidaktische Denkfiguren, um zu überlegen, inwiefern sie biografische Sinnkonstruktionen umfassen. Der Beitrag prüft, ob sich diese theoretischen Modelle anschlussfähig für biografisch orientierte historische Sinnbildung zeigen.
Differenzierende Lernaufgaben als Baustein für inklusiven Geschichtsunterricht
Authors: Buchsteiner Martin , Scheller Jan
Published: March 2021

Martin Buchsteiner und Jan Scheller verfolgen einen unterrichtspragmatischen Ansatz. Sie stellen ein Aufgabenraster vor, das die Anbahnung der historische Denkoperation, Quellen und Darstellungen zu analysieren, binnendifferenzierend unterstützt. Dafür wird die Analyse von Quellen und Darstellungen in Teiloperationen zerlegt und diese durch Aufgaben operationalisiert. Das Raster basiert auf dem lernpsychologischen Konzept des Cognitive Apprenticeship (vgl. Collins et al. 1989). Demnach werden Lernende zunächst durch Aufgaben, die alle Arbeitsschritte vorgeben, eng begleitet (Coaching, Scaffolding) und im weiteren schulischen Lernverlauf durch komplexere Aufgaben zu einer grösseren Selbstständigkeit beim Bewältigen der historischen Denkleistungen befähigt (Fading). Mit Hilfe des Aufgabenrasters erhalten Geschichtslehrpersonen ein Instrument um einschlägige Aufgaben gemäß der individuellen Lernvoraussetzungen ihrer Schüler/-innen zu bestimmen.