bluuebunny/crossref_metadata_2025 huggingface dataset:
Phage susceptibility testing and infectious titer determination through wide-field lensless monitoring of phage plaque growth
Authors: Perlemoine Prisca , Marcoux Pierre R. , Picard Emmanuel , Hadji Emmanuel , Zelsmann Marc , Mugnier Grégoire , Marchet Aurélie , Resch Grégory , O’Connell Larry , Lacot Eric
Published: March 2021

The growing number of drug-resistant bacterial infections worldwide is driving renewed interest in phage therapy. Based on the use of a personalized cocktail composed of highly specific bacterial viruses, this therapy relies on a range of tests on agar media to determine the most active phage on a given bacterial target (phage susceptibility testing), or to isolate new lytic phages from an environmental sample (enrichment of phage banks). However, these culture-based techniques are still solely interpreted through direct visual detection of plaques. The main objective of this work is to investigate computer-assisted methods in order to ease and accelerate diagnosis in phage therapy but also to study phage plaque growth kinetics. For this purpose, we designed a custom wide-field lensless imaging device, which allows continuous monitoring over a very large area sensor (3.3 cm2). Here we report bacterial susceptibility toStaphylococcus aureusphage in 3 hr and estimation of infectious titer in 8 hr 20 min. These are much shorter time-to-results than the 12 to 24 hours traditionally needed, since naked eye observation and counting of phage plaques is still the most widely used technique for susceptibility testing prior to phage therapy. Moreover, the continuous monitoring of the samples enables the study of plaque growth kinetics, which enables a deeper understanding of the interaction between phage and bacteria. Finally, thanks to the 4.3 μm resolution, we detect phage-resistant bacterial microcolonies ofKlebsiella pneumoniaeinside the boundaries of phage plaques and thus show that our prototype is also a suitable device to track phage resistance. Lensless imaging is therefore an all-in-one method that could easily be implemented in cost-effective and compact devices in phage laboratories to help with phage therapy diagnosis.
Pre-screening workers to overcome bias amplification in online labour markets
Authors: Vercammen Ans , Marcoci Alexandru , Burgman Mark
Published: March 2021

Groups have access to more diverse information and typically outperform individuals on problem solving tasks. Crowdsolving utilises this principle to generate novel and/or superior solutions to intellective tasks by pooling the inputs from a distributed online crowd. However, it is unclear whether this particular instance of “wisdom of the crowd” can overcome the influence of potent cognitive biases that habitually lead individuals to commit reasoning errors. We empirically test the prevalence of cognitive bias on a popular crowdsourcing platform, examining susceptibility to bias of online panels at the individual and aggregate levels. We then investigate the use of the Cognitive Reflection Test, notable for its predictive validity for both susceptibility to cognitive biases in test settings and real-life reasoning, as a screening tool to improve collective performance. We find that systematic biases in crowdsourced answers are not as prevalent as anticipated, but when they occur, biases are amplified with increasing group size, as predicted by the Condorcet Jury Theorem. The results further suggest that pre-screening individuals with the Cognitive Reflection Test can substantially enhance collective judgement and improve crowdsolving performance.
Forest cover mediates large and medium-sized mammal occurrence in a critical link of the Mesoamerican Biological Corridor
Authors: Salom-Pérez Roberto , Corrales-Gutiérrez Daniel , Araya-Gamboa Daniela , Espinoza-Muñoz Deiver , Finegan Bryan , Petracca Lisanne S.
Published: March 2021

Connectivity of natural areas through biological corridors is essential for ecosystem resilience and biodiversity conservation. However, robust assessments of biodiversity in corridor areas are often hindered by logistical constraints and the statistical challenges of modeling data from multiple species. Herein, we used a hierarchical community occupancy model in a Bayesian framework to evaluate the status of medium and large-sized mammals in a critical link of the Mesoamerican Biological Corridor (MBC) in Costa Rica. We used camera traps deployed from 2013–2017 to detect 18 medium (1–15 kg) and 6 large (>15 kg) mammal species in a portion of two Jaguar Conservation Units (JCUs) and the Corridor linking them. Camera traps operated for 16,904 trap nights across 209 stations, covering an area of 880 km2. Forest cover was the most important driver of medium and large-sized mammal habitat use, with forest specialists such as jaguars (Panthera onca) and pumas (Puma concolor) strongly associated with high forest cover, while habitat generalists such as coyotes (Canis latrans) and raccoons (Procyon lotor) were associated with low forest cover. Medium and large-sized mammal species richness was lower in the Corridor area (x¯= 9.78±1.84) than in the portions evaluated of the two JCUs (x¯= 11.50±1.52). Puma and jaguar habitat use probabilities were strongly correlated with large prey species richness (jaguar,r= 0.59, p<0.001; puma,r= 0.72, p<0.001), and correlated to a lesser extent with medium prey species richness (jaguar,r= 0.36, p = 0.003; puma,r= 0.23, p = 0.064). Low estimated jaguar habitat use probability in one JCU (Central Volcanic Cordillera:x¯= 0.15±0.11) suggests that this is not the jaguar stronghold previously assumed. In addition, the western half of the Corridor has low richness of large mammals, making it necessary to take urgent actions to secure habitat connectivity for mammal populations.
Szervezeti szocializáció – Mi az egyén szerepe saját szocializációs folyamatában? (II. rész)
Authors: Toarniczky Andrea
Published: March 2021

Jelen cikk célja a szervezeti szocializáció szakirodalmának áttekintése és rendszerezése a következő négy kérdés mentén: (1) a „Mit értünk szervezeti szocializáció alatt?” kérdésre keresve a választ a szerző definiálja a szocializációt, és a kapcsolódó fogalmak tárgyalása révén azt is tisztázza, hogy mi nem tekinthető annak; (2) a „Mi az idő szerepe a szocializációs folyamatban?” kérdés mentén tárgyalja a folyamat időben való meghatározottságát (véges vs. folytonos), valamint az idő természetének a jelentőségét (lineáris vs. ciklikus); (3) az „Egy vagy több?” kérdés a szervezeti kontextus egységes vagy töredezett jellegének a szocializációs folyamatra gyakorolt hatására világít rá, valamint (4) a „Mi az egyén szerepe a saját szocializációs folyamatában?” kérdés során pedig azt vizsgálja, hogy mit jelent a folyamat szempontjából, ha az egyénre mint passzív, befogadó, vagy mint aktív, alakító szereplőre tekintünk.
Új stratégiai kihívások – A hazai cégek kísérleti vizsgálata
Authors: Fülöp Gyula , Pelczné Gáll Ildikó
Published: March 2021

Ez a tanulmány a vállalati működés alapvető feltételeinek újraformálódásával kapcsolatos új stratégiai kihívásokkal foglalkozik. Az első részben sorra veszi azt a négy kikerülhetetlen, ugyanakkor helyi szinten sajátosan jelentkező tendenciát, amely kiindulópontot jelent bármely szervezet, vállalkozás stratégiájának megalkotásához. Ez a négy, egymással összefüggő trend: a globalizáció, az e-business, az erőforrás-szűkösség és a munkaerő-diverzitás. Ezt követően a hazai cégek kísérleti vizsgálata segítségével bemutatja, hogy a magyarországi nagyvállalatok milyen formában és mértékben vannak felkészülve az új stratégiai kihívásokra. Végül az empirikus felmérés következtetései a stratégiai irányváltozások, válaszlehetőségek meghatározásához szolgálnak megbízható alapul.
Temperature and Moisture Dependence of the Specific Heat of High Performance Concrete
Authors: Toman J. , Černý R.
Published: March 2021

The specific heat of two types of high performance concrete was measured in the temperature range from 20 °C to 1000 °C and in the moisture range from dry material to saturation water content. A nonadiabatic method was chosen instead of classical adiabatic treatments in order to meet the requirements following from the large representative elementary volume of the materials. The measured results reveal a significant temperature effect on the specific heat value. The influence of moisture is less important than the influence of temperature, but is also not negligible.
Erosion Wear of Axial Flow Impellersin a Solid-liquid Suspension
Authors: Fořt I. , Medek J. , Ambros F.
Published: March 2021

A study was made of the erosion wear of the blades of pitched blade impellers in a suspension of waste gypsum from a thermal power station (vol. concentration CV=18.3 %, particle mean diameter d=0.1 mm, degree of hardness “2.5”) and silicious sand (CV=10 %, d=0.4 mm, degree of hardness “7.5”) in water under a turbulent flow regime of agitated charge when complete homogeneity of the suspension was achieved. Experiments were carried out on pilot plant mixing equipment made of stainless steel (diameter of cylindrical vessel T=390 mm, diameter of impeller D=100 mm, impeller off-bottom clearance h=100 mm) equipped with four wall radial baffles (width b=39 mm) and an impeller with four inclined plane blades (pitch angle α =20°, 30°, 45°, relative blade width W/D=0.2) made either of rolled brass (Brinell hardness 40–50 BH) or of structural steel (Brinell hardness 100–120 BH) always pumping the liquid downwards towards the flat vessel bottom. Two erosion process mechanisms appear, depending on the hardness of the solid particles in the suspension: while the particles of gypsum (lower hardness) generate a uniform sheet erosion over the whole surface of the impeller blade, the particles of silicious sand (higher hardness) generate wear of the leading edge of the impeller blades, together with a reduction of the surface of the worn blade. The hardness of the impeller blade also affects the rate of the erosion process: the higher the hardness of the impeller blade, the lower the wear rate of the blade. This study consists of a description of the kinetics of the erosion process of both mechanisms in dependence on the pitch angle of the tested impellers. While the wear of the leading edge of the blade exhibits a monotonous dependence on the pitch angle, the sheet erosion exhibits the maximum rate within the interval of the pitch angles tested α ϵ <20°; 45°>.However, generally the pitch angle α =45° seems to be the most convenient angle of blade inclination when both investigated mechanisms of the blade erosion process are considered at their minimum rate.
A Mathematical Model of theDrying Process
Authors: Haghi A. K.
Published: March 2021

A convective drying model is proposed which may be used to describe the drying behavior of leather. Using this model, the calculated transient leather temperature agrees well with experimental values. Variations in temperature and moisture content distribution are solved using the finite-difference method. The effects of operation parameters, such as temperature and humidity in the dryer, initial moisture content of the leather, and heat and mass transfer coefficients are examined using the model.
Prospects for Advanced Engineering Design Based on Risk Assessment
Authors: Holický M.
Published: March 2021

Current approaches to the design of structures are based on the concept of target probability of failure. This value is, however, often specified on the basis of comparative studies and past experience only. Moreover, the traditional probabilistic approach cannot properly consider gross errors and accidental situations, both of which are becoming more frequent causes of failure. This paper shows that it is useful to supplement a probabilistic design procedure by a risk analysis and assessment, which can take into account the consequences of all unfavourable events. It is anticipated that in the near future advanced engineering design will include criteria of acceptable risks in addition to the traditional probabilistic conditions.
Fatigue Crack Initiation and Early Growth in GLARE 3 Fiber-metal Laminate Subjected to Mixed Tensile and Bending Loading
Authors: Chlupová A. , Heger J. , Vašek A.
Published: March 2021

A special open-hole sheet specimen of GLARE fiber-metal laminate was used to simulate mixed loading similar to the loading of a riveted hole in a real fuselage skin structure. The effect of cyclic tension and secondary bending loading was studied. The notch region was observed through a microscope in order to detect the first fatigue crack initiation during fatigue loading. The number of cycles prior to crack initiation was measured, and the crack growth rate in the surface layer of the laminate was evaluated. The specimens were subjected to fatigue damage investigation in the inner layers of the laminate after termination of the test. A significant effect of secondary bending on fatigue crack initiation and early crack growth was found. The experimental results are discussed in terms of local stress-strain conditions in the notch region evaluated by means of finite element calculation.
Improving Aircraft Design Robustness with Scenario Methods
Authors: Strohmayer A.
Published: March 2021

Compared to other industries, the aerospace sector is characterized by long product cycles in a very complex environment. The aircraft manufacturer has to base his product strategy on a long-term view of risks and opportunities in the transport industry but he cannot predict the development of relevant factors in this market environment with any certainty. In this situation, scenario methods offer a pragmatic way to limit the uncertainties and to work them up methodically, in order to derive recommendations for cost-intensive strategic decisions like for example the go-ahead for a new aircraft concept. By including scenario methods in the aircraft design cycle, the ‘design robustness’ can be improved, i.e. the design is not optimised for a prognosticated operating environment, but can cope with various possible future developments. The paper will explain the three fundamental aspects in applying scenario planning to the aircraft design process: requirement definition, design evaluation and technology identification. For each aspect, methods will be shown, which connect the rather qualitative results of a scenario process with aircraft design, which typically demands a qualitative input.
Aerodynamic Design of a Tailless Aeroplan
Authors: Friedl J.
Published: March 2021

The paper presents an aerodynamic analysis of a one-seat ultralight (UL) tailless aeroplane named L2k, with a very complicated layout. In the first part, an autostable airfoil with a low moment coefficient was chosen as a base for this problem. This airfoil was refined and modified to satisfy the design requirements. The computed aerodynamic characteristics of the airfoils for different Reynolds numbers (Re) were compared with available experimental data. XFOIL code was used to perform the computations. In the second part, a computation of wing characteristics was carried out. All calculated cases were chosen as points on the manoeuvring and gust envelope. The vortex lattice method was used with consideration of fuselage and winglets for very complicated wing geometry. The PMW computer program developed at IAE was used to perform the computations. The computed results were subsequently used for structural and strength analysis and design.
Analytical Model of Modified Traffic Control in an ATM Computer Network
Authors: Filip J.
Published: March 2021

The ABR class of ATM computer networks uses feedback information that is generated by net switches and destination and is sent back to a source of data to control the net load. A modification of the standard traffic management of the ATM network is presented, based on the idea of using RM cells to inform the source about congestion. An analytical model of a net switch is designed and mathematical relations are presented. The probability of queueing is considered. The analytical model of the switch was constructed for the purpose of analysing the network behaviour. It is used for investigating of cells passing through the network. We describe the model below. The submitted analytical results show that this method reduces congestion and improves throughput.
Models of Financing and Available Financial Resources for Transport Infrastructure Projects
Authors: Pokorná O. , Mocková D.
Published: March 2021

A typical feature of transport infrastructure projects is that they are expensive and take a long time to construct. Transport infrastructure financing has traditionally lain in the public domain. A tightening of many countries' budgets in recent times has led to an exploration of alternative resources for financing transport infrastructures. A variety of models and methods can be used in transport infrastructure project financing. The selection of the appropriate model should be done taking into account not only financial resources but also the distribution of construction and operating risks and the contractual relations between the stakeholders.
Solution of the Burgers Equation in the Time Domain
Authors: Bednařík M. , Koníček P. , Červenka M.
Published: March 2021

This paper deals with a theoretical description of the propagation of a finite amplitude acoustic waves. The theory based on the homogeneous Burgers equation of the second order of accuracy is presented here. This equation takes into account both nonlinear effects and dissipation. The method for solving this equation, using the well-known Cole-Hopf transformation, is presented. Two methods for numerical solution of these equations in the time domain are presented. The first is based on the simple Simpson method, which is suitable for smaller Goldberg numbers. The second uses the more advanced saddle point method, and is appropriate for large Goldberg numbers.
Study of Pumping Capacity of Pitched Blade Impellers
Authors: Fořt I. , Jirout T. , Sperling R. , Jambere S. , Rieger F.
Published: March 2021

A study was made of the pumping capacity of pitched blade impellers in a cylindrical pilot plant vessel with four standard radial baffles at the wall under a turbulent regime of flow. The pumping capacity was calculated from the radial profile of the axial flow, under the assumption of axial symmetry of the discharge flow. The mean velocity was measured using laser Doppler anemometry in a transparent vessel of diameter T = 400 mm, provided with a standard dished bottom. Three and six blade pitched blade impellers (the pitch angle varied within the interval a Îá24°; 45°ń) of impeller/vessel diameter ratio D/T = 0.36, as well as a three blade pitched blade impeller with folded blades of the same diameter, were tested. The calculated results were compared with the results of experiments mentioned in the literature, above all in cylindrical vessels with a flat bottom. Both arrangements of the agitated system were described by the impeller energetic efficiency, i.e, a criterion including in dimensionless form both the impeller energy consumption (impeller power input) and the impeller pumping effect (impeller pumping capacity). It follows from the results obtained with various geometrical configurations that the energetic efficiency of pitched blade impellers is significantly lower for configurations suitable for mixing solid-liquid suspensions (low impeller off bottom clearances) than for blending miscible liquids in mixing (higher impeller off bottom clearances).
Reliability of Concrete Elements Designed for Alternative Load Combinations Provided in Eurocodes
Authors: Holický M. , Marková J.
Published: March 2021

The basic European standard for design of buildings and other engineering works, EN 1990 "Basis of structural design", provides alternative design procedures, for which national choice is allowed. One of the most important questions concerns three fundamental combinations of actions for persistent and transient design situations in the Ultimate limit states. Simple examples of reinforced concrete elements show, that the alternative load combinations may lead to considerably different reliability levels. Probabilistic methods of structural reliability theory are used to identify characteristic features of each combination and to formulate recommendations. However, further calibration studies are urgently needed in order to prepare National annexes to EN 1990 on time.
A Short Note on Non-isothermal Diffusion Models
Authors: Ficker T.
Published: March 2021

Asymptotic behaviour of the DIAL and DRAL non-isothermal models, derived previously for the diffusion of water vapour through a porous building structure, is studied under the assumption that the initially non-isothermal structure becomes purely isothermal.
The Computing of the Influence of a Steady Element on the Polarization Spectrum
Authors: Cimbala R. , Kršňák I. , Kolcunová I.
Published: March 2021

This paper describes computation of the influence of a steady current element on the current response of insulation material. The steady element is always present. When the insulation is dry, it can be neglected. When moisture is present, the steady element has to be calculated. A decision can be made after examining the spectrum.
Twenty Years of Microtron Laboratory Activities at CTU in Prague
Authors: Vognar M. , Šimáně Č. , Chvátil D.
Published: March 2021

I for medical diagnostic purposes), et cetera. Participation of the microtron laboratory in the education of students of the faculty in various fields of applied dosimetry and other microtron applications is also discussed.
A Note on Normalised Distributions of DC Partial Microdischarges
Authors: Ficker T. , Macur J.
Published: March 2021

Statistical distributions (exponential and Pareto) of DC partial microdischarges running within sandwich electrode systems are discussed from the viewpoint of a normalisation procedure which may influence some features of the final distribution.
Risk Assessment in Advanced Engineering Design
Authors: Holický M.
Published: March 2021

Traditional methods for designing of civil engineering structures and other engineering systems are frequently based on the concept of target probability of failure. However, this fundamental quantity is usually specified on the basis of comparative studies and past experience only. Moreover, probabilistic design methods suffer from several deficiencies, including lack of consideration for accidental and other hazard situations and their consequences. Both of these extreme conditions are more and more frequently becoming causes of serious failures and other adverse events. Available experience clearly indicates that probabilistic design procedures may be efficiently supplemented by a risk analysis and assessment, which can take into account various consequences of unfavourable events. It is therefore anticipated that in addition to traditional probabilistic concepts the methods of advanced engineering design will also commonly include criteria for acceptable risks.
Die Design for Near-Net Shape Forging
Authors: Čermák J. , Gráf G.
Published: March 2021

This paper discusses the use of conventional forging equipment for the manufacture of precise forging without flash. An analysis is presented of the factors influencing the forging process and the conditions for establishing this technique in a forge based on practical experience at the SKODA Auto forge. The main problem is usually the excess volume of billet material. Three basic forms of die design for overload protection are illustrated and discussed.
Long-term Test Arrangement for Externally Strengthened Reinforced Concrete Elements
Authors: Vaňura T. , Štěpánek P. , Švaříčková I. , Adámek J.
Published: March 2021

Methods for external strengthening of concrete use elements of very high tensional strength glued on to its tensioned surface. These elements may be of metal, carbon fibers (CFRP), glass fibers or others, usually having very good mechanical properties. However, these high-strength elements are normally attached to concrete by epoxy resins. Epoxy resins have a low Young`s modulus and therefore a higher rate of creep may have an influence on the long-term behavior of such external strengthening. In order to verify this idea experimentally a special space-saving arrangement of tests is described in this paper. Panels act as loaded beams but simultaneously as a load for the other panels in a stand. The different load magnitude acting on a different layer of panels should make it possible to study the long-term influence of the degree of shear force on the glue creep. Certainly, the glue creep may be dependent on the type of epoxy resin; therefore several epoxy resin types are included in the tests.
To Whom Belongs Conceptual Design?
Authors: Bíla J.
Published: March 2021

The field of Conceptual Design is very alive and is rapidly developing. This paper investigates the disciplines and domains which substantially form its profile. There are considered disciplines such as Semiotics, Formal Logic, Evolutionary analogies, Qualitative Modelling, Ontologies, Artificial Intelligence and Emergent Synthesis. The answer to the question posed in the title lies nowadays in disciplines related to Cognitive Science.
Experimental Evaluation of Mountain Bike Suspension Systems
Authors: Titlestad J. , Fairlie-Clarke T. , Davie M. , Whittaker A. , Grant S.
Published: March 2021

A significant distinction between competitive mountain bikes is whether they have a suspension system. Research studies indicate that a suspension system gives advantages, but it is difficult to quantify the benefits because they depend on so many variables, including the physiology and psychology of the cyclist, the roughness of the track and the design of the suspension system. A laboratory based test rig has been built that allows the number of variables in the system to be reduced and test conditions to be controlled. The test rig simulates regular impacts of the rear wheel with bumps in a rolling road. The physiological variables of oxygen consumption and heart rate were measured, together with speeds and forces at various points in the system. Physiological and mechanical test results both confirm a significant benefit in using a suspension system on the simulated rough track, with oxygen consumption reduced by around 30 % and power transmitted through the pedals reduced by 30 % to 60 %.
Anisochronic Internal Model Control Design
Authors: Vyhlídal T. , Zítek P.
Published: March 2021

The features of internal model control (IMC) design based on the first order anisochronic model are investigated in this paper. The structure of the anisochronic model is chosen in order to fit both the dominant pole and the dominant zero of the system dynamics being approximated. Thanks to its fairly plain structure, the model is suitable for use in IMC design. However, use of the anisochronic model in IMC design may result in so-called neutral dynamics of the closed loop. This phenomenon is studied in this paper via analysing the spectra of the closed loop system.
A Direct Algorithm for Pole Placement by State-derivative Feedback for Single-input Linear Systems
Authors: Abdelaziz Taha H. S. , Valášek M.
Published: March 2021

This paper deals with the direct solution of the pole placement problem for single-input linear systems using state-derivative feedback. This pole placement problem is always solvable for any controllable systems if all eigenvalues of the original system are nonzero. Then any arbitrary closed-loop poles can be placed in order to achieve the desired system performance. The solving procedure results in a formula similar to the Ackermann formula. Its derivation is based on the transformation of a linear single-input system into Frobenius canonical form by a special coordinate transformation, then solving the pole placement problem by state derivative feedback. Finally the solution is extended also for single-input time-varying control systems. The simulation results are included to show the effectiveness of the proposed approach.
Implementation of Component-based Simulation Support Tool for Conceptual Design
Authors: Brandejský T.
Published: March 2021

Presented paper speaks about the problem of conceptual design stage simulation support. Simulation support is a very useful part of conceptual design system due to capability to verify ideas in early design stages. The problem excluding classical simulation tools is lack of information about designed device, is inconsistency and uncertainty. Thus specialised tool must be developed. The component-oriented editor of component descriptions and models is presented. This tool enables to describe components not only in terms of algebraic equations, but also by fuzzy rules. The problem of dynamic work with uncertainty representation during simulation and design processes is also solved. Presented tool also differentiates from standard tools like Mathematica or Matlab in its ability to work with component-based models, where each component is described from many aspects and only few of them are valid in concrete use. The tool must be able to select relations relevant in concrete simulation task and omit the rest.
Stellar Image Interpretation System Using Artificial Neural Networks:
Authors: Alawy A. El-Bassuny , Elnagahy F. I. Y. , Haroon A. A. , Azzam Y. A. , Šimák B.
Published: March 2021

A supervised Artificial Neural Network (ANN) based system is being developed employing the Bi-polar function for identifying stellar images in CCD frames. It is based on feed-forward artificial neural networks with error back-propagation learning. It has been coded in C language. The learning process was performed on a 341 input pattern set, while a similar set was used for testing. The present approach has been applied on a CCD frame of the open star cluster M67. The results obtained have been discussed and compared with those derived in our previous work employing the Uni-polar function and by a package known in the astronomical community (DAOPHOT-II). Full agreement was found between the present approach, that of Elnagahy et al, and the standard astronomical data for the cluster. It has been shown that the developed technique resembles that of the Uni-Polar function, possessing a simple, much faster yet reliable approach. Moreover, neither prior knowledge on, nor initial data from, the frame to be analysed is required, as it is for DAOPHOT-II.
Influence of ? Irradiation on Concrete Strength
Authors: Sopko V. , Trtík K. , Vodák F.
Published: March 2021

Aging of concrete due to gamma irradiation. Strength of concrete are in a good correspondency with already known results.
Computational Fluid Dynamic Simulation (CFD) and Experimental Study on Wing-external Store Aerodynamic Interference
Authors: Lazim Tholudin Mat , Mat Shabudin , Saint Huong Yu
Published: March 2021

The main objective of the present work is to study the effect of an external store to a subsonic fighter aircraft. Generally most modern fighter aircraft is designed with an external store installation. In this project a subsonic fighter aircraft model has been manufactured using a computer numerical control machine for the purpose of studying the effect of the external store aerodynamic interference on the flow around the aircraft wing. A computational fluid dynamic (CFD) and wind tunnel testing experiments have been carried out to ensure the aerodynamic characteristic of the model then certified the aircraft will not facing any difficulties in stability and controllability. In the CFD experiment, commercial CFD code is used to simulate the interference and aerodynamic characteristics of the model. Subsequently, the model together with an external store was tested in a low speed wind tunnel with test section sized 0.45 m×0.45 m. Result in the two-dimensional pressure distribution obtained by both experiments are comparable. There is only 12% deviation in pressure distribution found in wind tunnel testing compared to the result predicted by the CFD. The result shows that the effect of the external storage is only significant at the lower surface of the wing and almost negligible at the upper surface of the wing. Aerodynamic interference is due to the external storage were mostly evidence on a lower surface of the wing and almost negligible on the upper surface at low angle of attack. In addition, the area of influence on the wing surface by store interference increased as the airspeed increase.
Controlling Laminate Plate Elastic Behavior
Authors: Mareš T.
Published: March 2021

This paper aims to express the relation of a measure of laminate plate stiffness with respect to the fiber orientation of its plies. The inverse of the scalar product of the lateral displacement of the central plane and lateral loading of the plate is the measure of laminate plate stiffness. In the case of a simply supported rectangular laminate plate this measure of stiffness is maximized, and the optimum orientation of its plies is searched.
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 various group of scientists. This paper deals with the impact of electromagnetic radiation in housing spaces. The space is assumed to be bordered by 5 walls of ferroconcrete and a door-window combination on the 6th side, the latter to be electromagnetic transparent. The transparent side of the housing is exposed to an electromagnetic wave. As the source of radiation is considered to be far away from the housing, the radiation is regarded as a plane wave. Due to the high signal frequency and the ferroconcrete walls, 5 sides of the 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.
Developing Model for Supply Chain Management - the Case of Croatia
Authors: Jurun E. , Veza I.
Published: March 2021

This paper describes a model of supply chain management (SCM). It explains overall supply chain issues, strategic importance of SCM, supply chain strategies and an example of mathematical formulation. A supply chain is a global network of organizations that cooperate to improve the flows of material and information between suppliers and customers at the lowest cost and the highest speed. The objective of a supply chain is customer satisfaction. At the strategic level, a supply chain can be considered as being composed of five activities: buy, make, move, store and sell. Each activity is a module. The set of modules, along with its links, constitutes a model of the supply chain. Our paper presents some insights into the supply chain strategies of companies in Croatia. The major goal of this paper is to show a model for supply chain management in mathematical terms, with an example of mathematical formulation.
Influence of Matric Suction on the Shear Strength Behaviour of Unsaturated Sand
Authors: Farouk A. , Lamboj L. , Kos J.
Published: March 2021

As a part of the effort made to understand the behaviour of unsaturated soils, this work studies the shear strength characteristics of a cohesionless unsaturated soil. Generally, the determination of the shear strength of unsaturated soils is a great challenge to geotechnical engineers, both in terms of understanding it and the effort necessary to determine it. Matric suction is one of the stress state variables that control the shear strength of unsaturated soils. Therefore, the main aim of this study is to investigate the effect of matric suction on the shear strength characteristic of sand known commercially as Sand PR33. The shear strength behaviour of unsaturated sand is studied in this work using the constant water content triaxial test method with measurements of matric suction during the shearing stage. The tests were performed using the axis translation technique in such a way that the pore-air pressure was controlled while the pore-water pressure was measured during all tests.
Fractality of Electrostatic Microdischarges on the Surface of Polymers
Authors: Ficker T. , Kapička V. , Macur J. , Slavíček P. , Benešovský P.
Published: March 2021

Ramified Lichtenberg figures caused by electrostatic microdischarges on the surface of polymeric polyethylene terephthalate have been studied. They occurred in consequence of the previous electret forming of the polymeric sheets and were initiated in the air gap between the grounded electrode and the polymeric sheets. Multifractal image analysis was used to determine the fractal dimensions of the Lichtenberg patterns in dependence on the loading voltages used for electret forming.
Study of the Discharge Stream from a Standard Rushton turbine impeller
Authors: Kratěna J. , Fořt I.
Published: March 2021

The discharge stream from a standard Rushton turbine impeller exhibits special flow properties different from the characteristics of the velocity field in other parts of the volume of an agitated liquid in a cylindrical baffled vessel, e.g. two prevailing components of the mean velocity (radial and tangential), high rate of turbulent energy dissipation and anisotropy of turbulence in this region. At the same time, the discharge stream plays an important role in mixing operations, above all in liquid-liquid and gas-liquid systems.This paper deals with theoretical and experimental studies of the velocity field and flow of angular momentum in a discharge stream from a standard Rushton turbine impeller in a cylindrical baffled flat bottomed vessel under turbulent regime of flow of an agitated liquid with emphasis on describing the ensemble averaged values over the whole interval of the tangential coordinate around the vessel perimeter.
Pumping Capacity of Pitched Blade Impellers in a Tall Vessel with a Draught Tube
Authors: Brož J. , Fořt I. , Sperling R. , Jambere S. , Heiser M. , Rieger F.
Published: March 2021

A study was made of the pumping capacity of pitched blade impellers (two, three, four, five and six blade pitched blade impellers with pitch angles α = 35° and 45°) coaxially located in a cylindrical pilot plant vessel with cylindrical draught tube provided with a standard dished bottom. The draught tube was equipped with four equally spaced radial baffles above the impeller pumping liquid upwards towards the liquid surface. In all investigated cases the liquid aspect ratio H/T = 1.2 - 1.5, the draught tube / vessel diameter ratios DT /T = 0.2 and 0.4 and the impeller / draught tube diameter ratio D/DT = 0.875. The pumping capacity of the impeller was calculated from the radial profile of the axial component of the mean velocity in the draught tube below the impeller at such an axial distance from the impeller that the rotor does not affect the vorticity of the flow. The mean velocity was measured using a laser Doppler anemometer with forward scatter mode in a transparent draught tube and a transparent vessel of diameter T = 400 mm. Two series of experiments were performed, both of them under a turbulent regime of flow of the agitated liquid. First, the optimum height of the dished bottom was sought, and then the dependences of the dimensionless flow rate criterion and the impeller power number on the number of impeller blades were determined for both pitch angles tested under conditions of optimum ratio HT /DT. It follows from the results of the experiments that the optimum ratio HT /DT = 0.25 when the cross sectional areas of the horizontal flow around the bottom and the vertical inflow to the draught tube are the same. For all the tested pitched blade impellers the impeller power number when α = 45° exceeds the value of this quantity when pitch angle α  =   35°, while the flow rate number when α = 35° exceeds this quantity when α = 45°. On the other hand, the absolute values of the impeller power number when the draught tube was introduced correspond fairly well to the dimensionless impeller power input measured in a system without a draught tube. However, the absolute values of the flow rate number found in the former system are significantly lower than the dimensionless impeller pumping capacity determined in the latter system. The hydraulic efficiency of pitched blade impellers N3Qp/Po for the investigated geometry of the agitated systems does not depend on the number of impeller blades, but it is significantly lower than the quantity determined in an agitated system with a dished bottom but without the draught tube.
Size Effect in Fracture of Concrete Specimens and Structures: New Problems and Progress
Authors: Bažant Z. P. , Yu Q.
Published: March 2021

Presented is a concise summary of recent Northwestern University studies of six new problems. First, the decrease of fracture energy during crack propagation through a boundary layer, documented by Hu and Wittmann, is shown to be captured by a cohesive crack model in which the softening tail slope depends on the distance from the boundary (which causes an apparent size effect on fracture energy and implies that the nonlocal damage model is more fundamental than the cohesive crack model). Second, an improved universal size effect law giving a smooth transition between failures at large cracks (or notches) and at crack initiation is presented. Third, a recent renewed proposal that the nominal strength variation as a function of notch depth be used for measuring fracture energy is critically examined. Fourth, numerical results and a formula describing the size effect of finite-angle notches are presented. Fifth, a new size effect law derivation from dimensional analysis coupled with asymptotic matching is given. Finally, an improved code-type formula for shear capacity of R.C. beams is proposed.
OOFEM – An Object Oriented Framework for Finite Element Analysis
Authors: Patzák B. , Bittnar Z.
Published: March 2021

This paper presents the design principles and structure of the object-oriented finite element software OOFEM, which has been under active development for several years. The main advantages of the presented framework include modular design, extensibility, and robustness. The code itself is freely available and is distributed under GNU public license. It provides tools for linear and nonlinear analysis of mechanical and transport problems on sequential and parallel computers.
How Reliable is the Durability of RC Structures?
Authors: Teplý B. , Rovnaník P. , Keršner Z. , Rovnaníková P.
Published: March 2021

The goal of this paper is to show some trends and time profiles of the reliability index relevant to the Serviceability Limit State considering the design service life of RC structures. The interactive web page “RC_LifeTime” – originated by the authors – is used (see http://www.stm.fce.vutbr.cz/). The depassivation of reinforcing steel due to carbonation is considered conservatively as a limiting condition. It is based on model concrete carbonation with 12 random input variables; the Latin Hypercube Sampling simulation method is used. RC_LifeTime offers the following options: Service Life Assessment – a statistical evaluation of service life, where optionally the target value of reliability index ß may be an additional input value and then the corresponding service life is the output value; Concrete Cover Assessment – a statistical evaluation of concrete cover value for the target service life, where optionally the required concrete cover value may be input in this case and the relevant reliability index ß describes the reliability of reinforcement depassivation.
Neural Network Based Identification of Material Model Parameters to Capture Experimental Load-deflection Curve
Authors: Novák D. , Lehký D.
Published: March 2021

A new approach is presented for identifying material model parameters. The approach is based on coupling stochastic nonlinear analysis and an artificial neural network. The model parameters play the role of random variables. The Monte Carlo type simulation method is used for training the neural network. The feasibility of the presented approach is demonstrated using examples of high performance concrete for prestressed railway sleepers and an example of a shear wall failure.
Nondestructive Damage Detection Based on Modal Analysis
Authors: Plachý T. , Polák M.
Published: March 2021

Three studies of damage identification and localization based on methods using experimentally estimated modal characteristics are presented. The results of an experimental investigation of simple structural elements (three RC-beams and three RC-slabs) obtained in the laboratory are compared with the results obtained on a real structure (a composite bridge – a concrete deck supported by steel girders) in situ.
Dynamic Bridge Response for a Bridge-friendly Truck
Authors: Šmilauer V. , Máca J. , Valášek M.
Published: March 2021

A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model) with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions.
Effect of Stirrups on Behavior of Normal and High Strength Concrete Columns
Authors: Němeček J. , Padevět P. , Bittnar Z.
Published: March 2021

This paper deals with an experimental investigation and numerical simulation of reinforced concrete columns. The behavior of normal and high strength columns is studied, with special attention paid to the confinement effects of transversal reinforcement in columns with a square cross section. The character of a failure, and the strengths, ductility and post-peak behavior of columns are observed in experiments and also in numerical solution. A three-dimensional computational model based on the microplane model for concrete was constructed and compared with experimental data. The results of the numerical model showed good agreement in many aspects, and proved the capabilities of the used material model.
The Influence of Disorder in Multifilament Yarns on the Bond Performance in Textile Reinforced Concrete
Authors: Konrad M. , Chudoba R.
Published: March 2021

In this paper we analyze the performance of a bond layer between the multi-filament yarn and the cementitious matrix. The performance of the bond layer is a central issue in the development of textile-reinforced concrete. The changes in the microstructure during the loading result in distinguished failure mechanisms on the micro, meso and macro scales. The paper provides a brief review of these effects and describes a modeling strategy capable of reflecting the failure process. Using the model of the bond layer we illuminate the correspondence between the disorder in the microstructure of the yarn and the bonding behavior at the meso- and macro level. Particular interest is paid to the influence of irregularities in the micro-structure (relative differences in filament lengths, varying bond quality, bond-free length) for different levels of local bond quality between the filament surface and the matrix.