bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing analysis approaches for energy walls
Authors: Shafagh Ida , Loveridge Fleur
Published: November 2020

The use of diaphragm or bored pile walls as ground heat exchangers as well as embedded retaining structures has gained popularity in recent years. Dual use of structure foundations in this way has the potential to reduce the costs of associated ground source heat pump systems, hence providing opportunities for the take up of renewable heating and cooling in our cities. Such systems have been recently constructed as part of major infrastructure schemes in London and Paris. However, there are no standard analytical analysis approaches to permit routine design of the thermal aspects of these novel planar ground heat exchangers. Hence assessment of energy availability on most practical projects either (i) adapts existing methods from ground heat exchangers of different geometry, which runs the risk of incurring errors; or (ii) resorts to time consuming numerical simulation, often in partnership with a research organisation. Neither approach is sustainable for routine roll out of the technology beyond prestige projects. To start to fill this gap in knowledge, this paper presents the first feasibility assessment of developing specific analytical tools for use with energy walls.
Energy tunnel linings thermo-mechanical performance: comparison between field observations and numerical modelling
Authors: Insana Alessandra , Barla Marco , Sulem Jean
Published: November 2020

Energy linings are receiving great interest due to their potential to transform a tunnel into a smart energy system for enhancing thermal comfort of buildings and metro stations, as well as to absorb waste heat from the tunnel environment. Yet, besides their thermal performance, the impacts of equipping segments with a net of pipes are still challenging in the framework of energy tunnels structural design. Indeed, the thermal regime of the concrete members is altered due to heat carrier fluid circulation. Hence, the need to shed some light on the possible limit states attainment arises. In this paper, field monitoring of stresses and strains are presented for the first time in relation to a full scale monitored prototype of Enertun energy tunnel lining installed in Turin, Italy. Experimental data are compared to the results of a coupled thermo-mechanical numerical model, showing to be in good agreement. Criticalities from the ultimate limit state do not emerge, although a deeper analysis of serviceability limit states attainment should be performed.
A novel approach to the evaluation of contact thermal resistance at soil-structure interfaces
Authors: Figueira João Diogo , Bourne-Webb Peter , Bodas Freitas Teresa
Published: November 2020

Considering the need to reduce our dependence on unsustainable energy sources and reducing the carbon footprint associated with building climate control, shallow geothermal energy represents an attractive sustainable technology for providing renewable heating and cooling. The temperature field generated around ground-coupled heat exchangers, and thus their energy efficiency, fundamentally depends on the heat transfer mechanism and the thermal properties of the materials involved. While the thermal properties of materials that make up the system can be defined with some certainty, little is known about the impact of contact thermal resistance at the soil-structure interface. Contact thermal resistance will reduce heat exchange efficiency and increase mechanical impacts associated with temperature changes within energy geo-structures. This paper describes a laboratory test method to quantify the contact thermal resistance of soil-concrete interfaces. The methodology is first evaluated using numerical analysis, and then validated against a test using a limestone aggregate concrete and fine, silica sand at differing levels of compaction.
Finite element modelling of an energy-geomembrane underground pumped hydroelectric energy storage system
Authors: Stutz Hans Henning , Norlyk Peter , Sørensen Kenneth , Andersen Lars Vabbersgaard , Sørensen Kenny Kataoka , Clausen Johan
Published: November 2020

The increasing need for energy storage technology has led to a massive interest in novel energy storage methods. The energy geomembrane system is such a novel energy storage method. The concept of the system is briefly introduced, and a holistic numerical model of the system is presented. The model uses advanced finite-element techniques to model the energy storage system using fluid cavity elements. The developed geomembrane energy system is modelled with different constitutive models to represent the soil behaviour: a linear elastic model, a nonlinear Mohr-Coulomb model, and a hypoplastic constitutive model. The consequences of these different models on the results are studied. Hereby, the focus is the first inflation and deflation cycle of the system.
Role of initial effective stress on the thermal volume change of normally consolidated clay
Authors: Samarakoon Radhavi , McCartney John S.
Published: November 2020

This paper focuses on the results from thermal triaxial tests on normally consolidated Georgia Kaolinite. The hypothesis evaluated in this study is whether the initial mean effective stress has an impact on the thermal volume change encountered during drained heating. To that effect, specimens at three different initial mean effective stresses were considered in this study. The clay specimens were first isotropically consolidated to a normally consolidated state, then subjected to a drained heating cooling cycle followed by further mechanical loading to higher effective stresses. The results indicate contractive volumetric strain during drained heating where the volumetric strain was found to increase with increasing initial mean effective stress. A rebound in volume was observed during subsequent cooling where the net change in volume transitioned from zero volume change of the specimen to net contraction of the specimen after a heating cooling cycle as the initial mean effective stress increased. The results indicate the need for considering the effect of initial mean effective stress when assessing in-situ heating as a method of soil improvement.
Effects of temperature on consolidation and consistency of clayey soils
Authors: Ogawa Atsushi , Takai Atsushi , Shimizu Takumi , Katsumi Takeshi
Published: November 2020

This study focuses on the effects of temperature on the consolidation property and consistency of clay for thermal improvement of soft clay ground. Although it is already known that an increase in temperature can accelerate consolidation of clay, the degree of the temperature effect has not yet been generalized between various clays. In this study, a series of one-dimensional consolidation tests at different temperatures (17, 23, 35, 50, and 65°C) using 2 processed clays and 3 natural clayey soils dredged at ports are presented. To evaluate the temperature effect on soil consistency, which might affect the consolidation behavior, atterberg limits of the clays were also evaluated at different temperatures. As a result, it was confirmed that, although the temperature effect on consistency limits varies depending on the type of clay, the consolidation coefficient increases with increase in temperature in all the clay soils tested.
Heating-induced creep and potential creep rupture of clay liners for nuclear waste repository
Authors: Jaradat Karam A. , Abdelaziz Sherif L.
Published: November 2020

The aim of this study is to assess the potential of encountering a heating-induced creep rapture of clay liners in nuclear waste repository. Groundwater and soil contaminations may occur if the elevated temperatures, expected in the vicinity of nuclear waste repository, trigger creep rapture of the clay liners. In this study, we utilize simulations based on the discrete element method (DEM) to understand the conditions under which heating-induced creep rupture can take place. In lieu of the conventional local/non-local damping mechanism usually utilized in DEM simulations to dissipate energy, the DEM simulations presented in this study incorporate the rate process theory as a damping mechanism to model soil creep. The results of a base anisotropic model at 70 °C show a dramatic increase in the creep rate at high temperatures showing creep rupture. Such undesired behavior can be mitigated by engineering clay liner materials to sustain and resist the expected high temperatures expected around nuclear waste repository.
Geomechanical effects of carbon sequestration as CO2 hydrates and CO2-N2 hydrates on host submarine sediments
Authors: Yu Shuman , Uchida Shun
Published: November 2020

Over the past 10 years, more than 300 trillion kg of carbon dioxide (CO2) have been emitted into the atmosphere, deemed responsible for climate change. The capture and storage of CO2 has been therefore attracting research interests globally. CO2 injection in submarine sediments can provide a way of CO2 sequestration as solid hydrates in sediments by reacting with pore water. However, CO2 hydrate formation may occur relatively fast, resulting decreasing CO2 injectivity. In response, nitrogen (N2) addition has been suggested to prevent potential blockage through slower CO2-N2 hydrate formation process. Although there have been studies to explore this technique in methane hydrate recovery, little attention is paid to CO2 storage efficiency and geomechanical responses of host marine sediments. To better understand carbon sequestration efficiency via hydrate formation and related sediment geomechanical behaviour, this study presents numerical simulations for single well injection of pure CO2 and CO2-N2 mixture into submarine sediments. The results show that CO2-N2 mixture injection improves the efficiency of CO2 storage while maintaining relatively small deformation, which highlights the importance of injectivity and hydrate formation rate for CO2 storage as solid hydrates in submarine sediments.
Dynamic 3D imaging of gas hydrate kinetics using synchrotron computed tomography
Authors: Jarrar Zaher , Al-Raoush Riyadh , Alshibli Khalid , Jung Jongwon
Published: November 2020

The availability of natural gas hydrates and the continuing increase in energy demand, motivated researchers to consider gas hydrates as a future source of energy. Fundamental understanding of hydrate dissociation kinetics is essential to improve techniques of gas production from natural hydrates reservoirs. During hydrate dissociation, bonds between water (host molecules) and gas (guest molecules) break and free gas is released. This paper investigates the evolution of hydrate surface area, pore habit, and tortuosity using in-situ imaging of Xenon (Xe) hydrate formation and dissociation in porous media with dynamic three-dimensional synchrotron microcomputed tomography (SMT). Xe hydrate was formed inside a high- pressure, low-temperature cell and then dissociated by thermal stimulation. During formation and dissociation, full 3D SMT scans were acquired continuously and reconstructed into 3D volume images. Each scan took only 45 seconds to complete, and a total of 60 scans were acquired. Hydrate volume and surface area evolution were directly measured from the SMT scans. At low hydrate saturation, the predominant pore habit was surface coating, while the predominant pore habit at high hydrate saturation was pore filling. A second-degree polynomial can be used to predict variation of tortuosity with hydrate saturation with an R2 value of 0.997.
Comparison of advanced hydraulic properties between treated and untreated bauxite residue
Authors: Machado Joao A. R. , Kwan Wing Shun , Gore Matthew S. , Menezes Gustavo B.
Published: November 2020

Advanced hydraulic characteristics of treated and untreated Bauxite Residue (Red Mud) are studied and compared using a Steady-State Centrifugation (SSC) Unsaturated Flow Apparatus (UFA). Red Mud is the by-product waste from the Bayer process during aluminum production that has shown the potential of being reused as fill material in embankment construction, which can reduce the energy consumption of disposing the minging waste and producing fill materials. There is a limited number of documented studies on unsaturated hydraulic characteristics of RM. Furthermore, the high alkalinity (pH > 12) of the bauxite slurry is a challenge for reusing the material. Past studies have shown two effective and economic neutralization methods: (i) mixing with seawater and (ii) addition of gypsum. This study utilizes Cal State LA centrifuge facilities to characterize the unsaturated hydraulic properties of the treated and untreated Red Mud. The experimental results are used to develop the Soil Water Retention Curve (SWRC) for the three types of Bauxite Residue: untreated, treated with saline solution, and treated with gypsum. The results show that adding gypsum is more effective than mixing with saline solution in reducing the pH value of RM, and the samples treated with saline solution provide the lowest range of unsaturated hydraulic conductivity values compared with the other two types.
Castanea sativaMill. plantations as a low-carbon landslide hazard mitigation measure
Authors: Dias Ana Sofia , Stokes Alexia , Pirone Marianna , Urciuoli Gianfranco
Published: November 2020

In the last twenty years, several rainfall-induced landslides occurred in areas surrounding Mount Vesuvius (Campania, Italy). Landslides usually involve the shallow pyroclastic soil layers (2-3 m thick) covering the steep slopes of the Lattari Mountains. The cultivation of trees for fruit production on the pyroclastic cover is a common practice by local farmers. Woody vegetation contributes to slope stability through the mechanical reinforcement of soil by roots. We investigated the use of Sweet chestnut (Castanea sativaMill.) trees as a low-carbon landslide mitigation measure to be applied in large areas where conventional geotechnical engineering solutions would be costly and extremely invasive, in order to respond to the demand in energy and environmental geotechnics for eco-friendly approaches. The root distribution ofC. sativain terms of root volume ratio was determined from soil cores. The mechanical reinforcement of soil by tree roots was quantified based on root-soil interaction models. Slope stability was analysed by means of limit equilibrium analyses performed on an infinite slope. The safety factor calculated for a cultivated slope was higher than for a fallow slope due to the mechanical reinforcement provided by roots. Therefore, the cultivation ofC. sativais a useful mitigation measure against shallow landslides.
On the potential of gassy marine soils triggering submarine slope instabilities
Authors: Kaminski Pauline , Grabe Jürgen
Published: November 2020

The development of debris flows and turbidity currents in the course of a submarine slope failure event can cause major damage in offshore infrastructure. Additionally, the tsunamogenic potential of large slope failures at continental margins poses a direct threat to coastal communities. Therefore, the trigger mechanisms of submarine slope failures have been thoroughly investigated in the past. However, the influence of free gas in the sediment, which has been observed close to several slide events, remains unexplained. In order to evaluate the potential of gassy marine soils to precondition or trigger slope failure the mechanical behaviour of gassy soils is assessed based on an extensive literature review. It is found that gas-induced excess pore pressures can lead to liquefaction failure in sands, while cohesive, gassy soils show a less conclusive response. Hence, fine-grained soils and approaches to implement the gas impact into relevant existing constitutive soil models are assessed in greater detail. Concludingly, based on the predominant boundary conditions in failure prone regions at the continental margins, free gas occurrence can be defined as a preconditioning factor rather than as a definite trigger mechanism.
Life cycle cost analysis of different residential heat pump systems
Authors: Doseva Nadezhda , Chakyrova Daniela
Published: November 2020

Nowadays, the application of air-source heat pumps for heating and cooling in residential buildings has been increased significantly. The main occasion for this is the accessibility of a heat source for these devices - the external air. Nevertheless, the increase of the energy efficiency of the air source heat pump systems is a difficult design problem because their capacity and performance are a function of the dynamically changing parameters of the outdoor air. Because of that, the main aim of this study is to develop an approach for choosing a structural scheme of an air-to-water heat pump system under specific climatic conditions. The considered systems are monovalent, bivalent-parallel and bivalent-alternative heat pump systems. In the current paper is conducted a dynamic energy modeling of heating and cooling demand of a typical residential building situated in Varna, Bulgaria and applying the bin temperature data. It is assessed the effect of the heat pump capacity over the annual and seasonal energy performance of the heat pump systems. It is established the effect of the bivalent temperature, cut-off temperature and on-off cycles duration on rates of the criteria for techno-economic assessment. The seasonal coefficient of performance (SCOP), seasonal energy efficiency rate (SEER) and life cycle costs (LCC) of the analyzed heat pump systems are adopted as assessment parameters.
Energy Performance of a Kalina Cycle based CHP plant driven by low-enthalpy geothermal sources
Authors: Mocanu Gabriel , Ion Ion V. , Popescu Florin
Published: November 2020

The low-enthalpy geothermal sources can be efficiently exploited for heat and power cogeneration by using the KCS-34 Kalina cycle systems. The maximum power for given heat source temperature and cooling temperature is obtained for a certain value of the ammonia-water solution concentration and turbine exit pressure. The Cycle-Tempo simulation software is a very useful tool to investigate variation of some cycle parameters in order to obtain the maximum energy efficiency. In this paper the performance of a KCS-34 Kalina cycle based CHP plant is investigated to exploit a geothermal source with 120°C temperature present in North-West of Romania. It was found that by using the heat and power cogeneration the energy efficiency can be increased from 16.76% to 57.86% in winter and to 33.44% in summer.
Physicochemical and thermodynamic properties of solutions of clary sage (Salvia sclarea L.) essential oil in ethanol-water system
Authors: Tasheva Stanislava , Gandova Vanya , Dobreva Krasimira , Prodanova-Stefanova Vanya , Marinova Krasimira , Dincheva Ivayla , Stoyanova Albena
Published: November 2020

Clary sage (Salvia sclarea L.) essential oil-ethanol-water system was investigated. The surface tension, density and refractive index of clary sage essential oil + ethanol (70%, 75%, 80%, 85%, 90%, and 95%) solutions were measured. The chemical composition of solutions (ratio 1:5, 1:6, and 1:7) was determined using GC/MS analysis. According the experimental results ternary phase diagrams were constructed. Comparative revue between experimental and calculated surface tension data was done. After analyses good correlation between two surface tension values was observed
Energy from municipal solid wastes: Galati city case study
Authors: Carp Bogdan Gabriel , Mocanu Gabriel , Ion Ion V. , Popescu Florin
Published: November 2020

The municipal solid wastes (MSW) can be turned into resources through recycling and energy recovery. To obtain the maximum amount of energy, the appropriate technology must be applied to waste treatment. The composition and characteristics of municipal solid wastes are determinant for technologies choice for MSW in a city/region. Municipal authorities from the Galati city proposed a recovery rate of recyclable materials of 60% from MSW and treatment of the post-recycling MSW as follow: biodegradable fraction by anaerobic digestion and the combustible fraction by incineration or gasification. In this study traditional and innovative waste to energy technologies have been analysed and the potential of electrical energy of waste has been estimated. Results show that plasma gasification system of raw MSW coupled with gas turbine engine has almost the same electrical energy production (32.92 GWh/year) as conventional gasification of combustible material from MSW (17.21GWh/year) coupled with anaerobic digestion of organic fraction of MSW (11.65 GWh/year). By recovering and using the landfill gas from the Tirighina landfill, 6.68 GWh of electricity can be produced annually.
Wind Energy Potential for Electricity Production in Hatay, Turkey
Authors: Genç Cansev , Sakalli Abdulla , Stoyanov Ivaylo , Iliev Teodor , Mihaylov Grigor , Beloev Ivan
Published: November 2020

In this study, we examine Turkey’s Hatay city and some of its districts (Belen, Antakya, Iskenderun, Samandag) and we assessed the possibility of electricity production from wind power plants. The area of Hatay is 5559 km2 that is located in the southernmost part of Turkey and east of the Mediterranean Sea. The accumulated data obtained from Belen- Hatay wind speed data are shown. The seasonal cumulative probability distributions of wind speeds for Belen-Hatay are analysed in the paper. The wind speeds in summer are higher than in the other seasons. As a result, the Belen-Hatay region is a very favourable place in terms of wind and has high wind energy potential. In this region, the hourly wind speeds are higher than 5 m/s and about 70% of occasions at 10 m height above ground level. It is also known that for nine months of the year, the average wind speeds are more than 5 m/s. On the other hand, average monthly wind energy productions are higher than 200W/m2 for eight months of the year.
Design of Adaptive Fuzzy PID Controller for Electropneumatic System
Authors: Ormandzhiev Krasimir , Yordanov Stanimir
Published: November 2020

The purpose of the study is to develop an adaptive electropneumatic automatic system based on the classical PID controller using modern technology for controlling like fuzzy controlling. The need of an adaptive setting occurred because of the fact that the classic controller has high sensitivity towards interferences with the main signal and the need for the parameters to be regulated often and be done by hand. Another reason is the inability to provide optimal parameters for the controller for nonlinear processes and changes of the parameters in time. In this article the work of electropneumatic system with linear actuator, is examined. A mathematical model describing the dynamics of the processes, is developed. An adaptive fuzzy PID controller with variable coefficients is synthesized. The system is studied in the environment of Matlab Simulink. The transient processes in the system are compared to processes where the classical PID controller. The results are presented in graphical form.
Determining the minor loss coefficient of cone diffusers
Authors: Popov Gencho , Klimentov Kliment , Kostov Boris , Dimitrova Reneta
Published: November 2020

This work represents results concerning different methods, used to determine the minor loss coefficient of a cone diffuser, installed at the system’s outlet. These results are compared with experimental data and numerical results, obtained after using ANSYS CFX and the data base of Pipe Flow Expert. For determining the minor loss coefficient of a cone diffuser, being installed at the system outlet and having a straight pipe section in front of it, some models in ANSYS CFX are established. These models are validated by using previously published experimental data. An empirical equation, based on the results found, enabling the accomplishment of analytical studies concerning the energy efficiency of fan systems, using an outlet diffuser, has been established.
CFD computation of flow in the flow path of a torque flow pump
Authors: Svoboda Dmitry , Borshchev Igor , Zharkovskii Aleksandr , Tvanov Evgeniy , Klyuyev Arsentiy
Published: November 2020

The results are presented of numerical and experimental research of fluid flow in the flow path of a torque flow pump with specific speed ns ;: 55. The 3D methods of CFD have been shown to allow for predicting energy characteristics of this type of pumps with a sufficient accuracy. According to the results of flow visualization the work process has been analysed and conclusions drawn to enhance TFP efficiency.
Two-dimensional numerical tests, of drag compensation device for on-road freight vehicles, based on CFD methods
Authors: Ivanov Martin
Published: November 2020

In today’s demanding reality, making the on-road freight vehicles more fuel-efficient and lower emissive, is becoming more and more important design issue. During the past years the light car industry has managed to reduce significantly the aerodynamic losses, whereas the freight transport did not have much development in this aspect. For heavy vehicles such as tractor-trailers, drag is one of the dominant reasons for energy loss due to poor aerodynamic shape and large surfaces facing the flow direction. That is why, the presented study focuses on the development of technological solution for aerodynamic loss compensation, devoted to the freight transport vehicles. An innovative approach for drag compensation, based on airfoil device located in the tractor-trailer gap, is tested by the methods of the Computational fluid dynamics (CFD), in 2D simulation study. The lift and drag force distribution over the airfoil are analyzed in the restricted area, in relation to the airfoil size. The results show that, the values increase with the increase of the size of the profile. However, important model limitations are described as well, which will assist the further development of the proposed device.
Replication of Pressure Swirl Atomizer by 3D Printing and Influence of Surface Roughness on the Atomization Quality
Authors: Cejpek Ondřej , Malý Milan , Bělka Miloslav , Jedelský Jan
Published: November 2020

The replication of atomizers by 3D printing technology is a new approach of producing the pressure swirl atomizers. The surface roughness of 3D printed products and manufacturing accuracy of the 3D printing process influence the atomization of the liquid. The high-speed visualization of a spray, produced by scaled 3D printed atomizer, was performed. The spray stability, cone angle and breakup length were determined. Scaled 3D printed atomizers were tested at equivalent pressures of 0.25, 0.5 and 1 bar. Non-dimensionless parameter, Reynolds number, was preserved for the scaled atomizer. The effect of the surface roughness of the tangential ports, swirl chamber and discharge orifice on atomization was assessed at non-scaled pressure swirl atomizer. The roughness of a swirl chamber was created by corundum and ballotin blasting. The inlet pressures of 2.5, 5 and 10 bar were tested.
Automatic Measurement of Material Weight Based on Energy Load in Assembly Line Drives
Authors: Klačková Ivana , Zajačko Ivan , Císar Miroslav
Published: November 2020

The management of the universal self-stacker in the assembly line handles many different operations, which differ in the complexity of the solved problems, the response time of the controller, energy and other parameters. It is usually used one controller with all the features that have a lot of external input-output modules and have to deal with many tasks in parallel. The management application must be very complicated and blind with the risk of collision management processes and the need to address the priority of the management process. If the processes are divided into groups, each group of processes is solved by a separate controller. For simple processes, where appropriate, can be used for immediate response simple and easy to control, it is necessary to solve complex management processes using a controller with sufficient power, energy load, math performance and sufficient memory.
Newly build tract for measuring regenerative heat exchangers
Authors: Sehnalek Stanislav , Zalesak Martin
Published: November 2020

This article describing newly build tract for measuring regenerative heat exchangers. At the beginning of this work is summarised measuring of heat recovery exchangers, parameters of heat recovery exchangers and conditions of measurements. This article continuous with the introduction of HVAC laboratory for which new track is built. Particular emphasis is on measuring box in which are exchangers measured.
Numerical and Analytical Calculation of Flow During Steam Blowing
Authors: Hoznedl Michal , Gregor Karel
Published: November 2020

In the paper results are described of numerical simulations of the flow during the steam blowing between the boiler drum and the outlet to the atmosphere. Numerical flow simulations are compared to the analytical approach that best describes the flow during the blowing, i.e. the Fanno flow. The proposed methodology of analytical calculation can be, with a reasonable deviation from reality, used in control of velocity and flow in the pipe outlet cross-section.
Experimental Verification of the Performance of the Floor Cooling System in Comparison with the Ceiling Cooling System While Maintaining Thermal Comfort in the Environment
Authors: Mičko Pavol , Kapjor Andrej , Kubas Šimon , Vantúch Martin
Published: November 2020

The trend of constantly increasing energy prices can be observed especially in the increased demands on the thermal insulation properties of building structures. The possibilities of reducing the energy intensity of residential buildings also include the right choice of technology for heating, cooling and hot water preparation. Different cooling systems have different proportions of convection and radiant components. This results in a variety of temperature profiles, and thus also directly affect the quality of the environment in terms of thermal comfort. For efficient heating, it is therefore best to choose a cooling system with a minimum temperature gradient in both the horizontal and vertical directions. At the same time, however, the investment costs for the cooling system must be considered. From this point of view, it seems to be most advantageous to use one system for both heating and cooling. From the point of view of comfort, the most suitable choice of cooling system is ceiling cooling. On the contrary, this system is less suitable for heating compared to the floor system. Therefore, if you are considering the design of a system that will be the greater part of the operation for heating the building and during the summer months will be used to increase thermal comfort by cooling in buildings with lower heat loads [1].
Numerical Modelling of Round Impinging Jet Heat Transfer Using Scale-Resolving-Simulation Methods: Influence of Local Grid Refinement
Authors: Kořínek Tomáš , Tisovský Tomáš
Published: November 2020

An accurate prediction of heat transfer is crucial in many engineering applications and a typical representative is heat transfer of impinging jets. The present study addresses numerical simulations using three Scale-Resolving-Simulation methods, namely the Detached Eddy Simulation, Large Eddy Simulation and the Partially Averaged Navier-Stokes. The study focus on the influence of a local grid refinement on predicted heat transfer. The closest match with experimental data was achieved with DES and PANS (fk = 0.5) models for all computational grids. The grid refinement led to an improvement of predicted results for LES and PANS with a high physical resolution (fk = 0.25).
Numerical Simulations of Flow in Electrostatic Precipitators
Authors: Matas Richard , Novák Martin , Kňourek Jindřich
Published: November 2020

Electrostatic precipitators are widely used in power generation and industry to separate solid particles from flue gases. They need relatively homogeneous distribution of the flue gas inside otherwise the required efficiency cannot be ensured. The paper shows how to approach some of possible troubles with distribution of the stream inside of the filters caused by unsuitable design of ducts in front of the device or by inlet parts of filters. Three filters in operation are presented as examples which seem to be similar, but their behaviour is different. CFD simulations partialy validated by measurement were used to evaluate the existing flow situation. Design changes were proposed and further investigated to improve the flows in the precipitator.
Study of Human Phonation with Attention on Sub-Grid Scale Turbulence Models and Initialization Effects
Authors: Lasota Martin , Šidlof Petr
Published: November 2020

The first aim of this paper is to compare three cases, where two cases contain turbulence sub-grid scale (SGS) models, which are commonly applied in wall-bounded flows. They use a bit different formulation of how to estimate the eddy-viscosity fields in a vicinity of walls. The SGS effect is obvious on flow rates through an intra-glottal gap. The second aim is to attend to a direct impact of the specific SGS model onto the sound pressure levels of frequency components (human formants). The third aim is focused on the effect of an initial time, when the vocal folds are in a start convergent phase itself and when the flow is suddenly accelerated due to boundary conditions. The effect is shown at aeroacoustic spectra.
Drying of Steaming Maple Timber in Drying Kilns, While Preserving the Color Acquired by the Wood Steaming Process
Authors: Dzurenda Ladislav
Published: November 2020

The paper presents a mode for drying steaming maple timber of thicknessh= 38 mm from moistureW1= 50 % toW2= 10 %, while preserving the color of wood obtained by the steaming process. The drying process is divided into two parts. Evaporation of free water from wet wood at drying medium temperaturestd= 35 - 40 °C and evaporation of water from wood below the hygroscopicity limitW≤ 25 % at drying medium temperaturestd= 70 - 80 °C. Total color differenceΔE*determined by the difference in values on the CIEL*a*b*color space coordinates dried by the proposed mode for steaming maple timber and the reference valuesΔE*= 1.03. According to the categorization of wood color changes in thermal processes by work (Cividini et al. (2007), this change belongs to the category of small color changes. A negative aspect of this drying mode is the approx. 25 % increase in timber drying time.
Quasi-unsteady Flow Field Computation and Performance Prediction of Contra-Rotating Fan
Authors: Červenka Bystrík , Holubčík Michal , Malcho Milan
Published: November 2020

Discussion of numerical flow field prediction with two rotor-stator interface models is presented in the paper. The mixing plane and harmonic models are applied to contra rotating fan. Both models confirmed good performance and high power density leading to compact configuration of the contra rotating fan compared to centrifugal fan. The harmonic model provides realistic wake and potential effect propagation through the rotor-rotor interface. In addition, it provides user with static pressure frequency and amplitude inputs for aerodynamic noise assessment.
Sterilization of Biofilm in Foam Using a Single Cavitation Bubble
Authors: Schovanec Petr , Jasikova Darina , Kotek Michal , Havlicek Karel , Nechanicka Magda , Eichler Jakub , Cech Jiri , Subrtova Petra
Published: November 2020

This article presents the sterilization of bacteria using cavitation bubbles. Cavitation generated by ultrasound creates a cavitation cloud. Therefore is more advantageous to generate the cavitation bubbles by laser-induced breakdown, because it is possible to generate individual bubbles for the purpose of study single impact and physical mechanism of acting. The cavitation bubble is generated by a Nd: YAG 532nm laser beam, a short 10ns pulse. Here, we used optics to focus the laser beam and a high-speed camera to visualize characteristics the bubble. We used the method of long-distance microscopy and shadowgraph lightening for the visualization. We used the particle image velocimetry (PIV) method to determine the interaction of the bubble with the surrounding liquid and solid surface. The main goal of the research is to use cavitation to sterilize bacteria and biofilm in impact of single bubble collapse on living cells.
POD Spectrum of the Wake behind a Circular Cylinder
Authors: Uruba Václav , Procházka Pavel
Published: November 2020

The wake dynamics behind a long circular cylinder in cross-flow was studied using the POD method. The temporal parts of POD modes, Chronoses, are subjected to frequency analysis. Five groups of modes are distinguished according to the frequency contents. The low order high energy modes contain the vortex shedding frequency or its harmonics up to 3rd order plus Kolmogorov spectrum. The higher order modes are characterized by combination of Kolmogorov spectrum with the white noise spectrum, its importance grows with the mode order. The very high order modes are characterised by the white noise spectrum only.
Particle Imaging Velocimetry Measurement of Air Flow Between High Voltage Asymmetrical Electrodes
Authors: Primas Jiří , Malík Michal , Schovanec Petr , Novák Josef , Pokorný Pavel , Sanetrník Filip
Published: November 2020

This paper deals with the airflow generation phenomenon occurring on a system of strongly asymmetrical electrodes connected to high DC voltage. The main focus was to measure the airflow directly between the electrodes using Particle Image Velocimetry. The authors are well aware of the many difficulties presented by the task of measuring in the presence of strong electric fields and the paper also describes the means used to overcome these issues. The results of performed measurements are presented, their agreement with theoretical description of given phenomenon is discussed and several possible practical applications are proposed.
Application de la biocicatrisation à la réparation des micro-fissures au sein d’enceintes de réacteurs nucléaires
Authors: Lors Christine , Damidot Denis , Petit Laurent , Tran Nhu Cuong , Legrix Alexis , Masson Benoit
Published: November 2020

La précipitation de carbonate de calcium par les bactéries constitue une méthode prometteuse pour la réparation des matériaux cimentaires fissurés. Une des applications potentielles de la biocicatrisation est la maintenance des enceintes nucléaires. Les objectifs de cette étude sont, dans un premier temps, de déterminer par des essais de laboratoire si le colmatage de fissures induit par la biocicatrisation persiste après une mise sous pression comparable à celle d’un essai décennal et, dans un deuxième temps, d’appliquer le traitement par bioprécipitation à une réplique à l’échelle 1/3 d’une enceinte de réacteur nucléaire (VERCoRs), qui a ensuite été soumise à une pressurisation à 500 kPa. Les résultats obtenus en laboratoire montrent que le cycle de pression ne modifie pas l’ouverture apparente des fissures, sur lesquelles a été appliqué le traitement par bioprécipitation, démontrant ainsi que le composite formé par le carbonate de calcium biogénéré et le biofilm n’est pas altéré par un flux d’air ayant une pression de l’ordre de 500 kPa. De même, le traitement par bioprécipitation réalisé sur la maquette VeRCoRs a montré son efficacité dans les zones où les déformations du béton au cours de la pressurisation sont restées minimes.
Evaluation of the ability of alkalophilic bacteria to form a biofilm on the surface of Portland cement-based mortars
Authors: Martinez Hernandez Heriberto , Gueguen Minerbe Marielle , Pechaud Yoan , Sedran Thierry
Published: November 2020

This paper investigates bacteria colonisation through biofilm formation, based on the premise that biofilm helps bacteria to have a better development. The aim is to homogenize bacterial growth on recycled concrete aggregates (RCA) to obtain a homogeneous precipitation of calcium carbonate (CaCO3). In previous studies, Bacillus halodurans C-125 was selected to perform biocarbonation on RCA to generate a coat of CaCO3 and diminish water absorption. Contrary to expectations, its poor development led to an heterogeneous CaCO3 precipitation, resulting in an inefficient treatment. Within the framework of this criterion the genetic information of B. halodurans C-125 was compared with a homologous specie “Bacillus subtilis str. 168” to know if it possessed the genes to encode Tas A and Tap A proteins. These proteins consolidate a robust biofilm in Bacillus subtilis str. 168, which promotes bacterial development and adhesion to a surface. Remarkably, B. halodurans C-125 lacks the genes to produce Tas A and Tap A. B. halodurans C-125 was also compared with a group of bacteria isolated from RCA to produce biofilm on MSgg media. Curiously, B. halodurans C-125 did not form a robust biofilm while the bacteria isolated from RCA did. Because of the capacity of the isolated bacteria to form biofilm, they were inoculated on a mortar disk with nutrient and MSgg broth. The results showed traces of bacterial development and precipitation of CaCO3 in form of calcite.
Rhétoriques inclusives et subversions de la défectologie
Authors: Kohout-Diaz Magdalena
Published: November 2020

L’article propose une analyse du déploiement de l’éducation inclusive. Cette notion désigne tout à la fois une transformation profonde de l’éducation à l’échelle mondiale pour aller dans le sens des idéaux éducatifs (équité, lutte contre toute forme de discrimination) et unstatu quolié à une labellisation stigmatisante des diversités sous des formesdéfectologiques(Vygotski, 1927-1935) dont elle est censée se démarquer. Nous proposons non pas de faire déconsister le terme dedéfectologiemais de lui donner - à partir de l’étude brève de deux cas - une signification différente. Nous la croyons conforme à l’esprit des travaux de L. S. Vygotski dans la mesure où la défectologie serait une science de la singularité [iedinstvo], dont il est impossible de rendre compte sans une inventionad hocdes mots pour la dire. À accompagner les sujets dans cette élaboration se construit un style professionnel inclusif qui consiste dans un travail continu (éventuellement collectif) sur sa propre fonction d’interprète de la diversité. C’est une autre manière de travailler qui n’occasionne pas épuisement et souffrance à la manière dubenchmarkinget durankingactuels, mais qui se propose, plutôt de mieux être lié à la prise en compte de la subjectivité.
Inclusion scolaire d’élèves avec TSA : pour l’inclusion de la notion de sujet
Authors: Bastos Marise Bartolozzi
Published: November 2020

Ce travail est le fruit de nos recherches dans la formation de professeurs des écoles au Brésil. Il aborde les impasses vécues dans le processus d’inclusion scolaire d’élèves avec un trouble du spectre autistique (TSA). L’un des principaux problèmes qui se présente dans la scolarisation de ces enfants est constitué par les difficultés qu’ils rencontrent dans l’établissement de relations avec les autres, ce qui peut parfois aussi engendrer des impasses face aux apprentissages scolaires. L’inclusion scolaire de ces élèves requiert de la part des enseignants un changement de position face aux processus usuels de l’acte d’enseigner et d’apprendre. La scolarisation d’enfants psychotiques et autistes doit être pensée dans une perspective qui inclut la notion de sujet freudien. Un paradigme très différent de l’agent de l’action présent dans les théories pédagogiques contemporaines, et du développement de compétences prescrit dans les théorisations de la formation d’un « enseignant réflexif ». Nous souhaitons montrer comment nos expériences universitaires nous portent à analyser non seulement la question de l’inclusion de l’enfant en tant que sujet dans les dispositifs scolaires, mais aussi la nécessaire inclusion de l’enseignant en tant que sujet dans des dispositifs de formation qui favorisent la circulation de la parole.
« Être ou ne pas être, telle est la question » : de l’inobservance à l’observance du traitement antirétroviral
Authors: Voutyra Marina , Ameziane Abdelhak , Moro Marie Rose
Published: November 2020

La prise du traitement antirétroviral est l’objet du présent article chez des patients atteints du VIH et venant d’un différent contexte socio-culturel. L’inobservance du traitement est souvent attribuée par les soignants à la non-adhésion du patient. Notre hypothèse clinique est que le VIH est un virus qui fait émerger entre autres des traits paranoïaques qui peuvent éventuellement altérer la relation soignant-patient et par conséquent la prise du traitement. L’articulation avec la pratique au sein d’un service médico-social permet l’illustration de notre hypothèse avec des vignettes cliniques issues du suivi psychologique bimensuel, tout en s’appuyant aux travaux psychanalytiques, transculturelles et de l’anthropologie médicale. Pour ces patients dont le vécu a été particulièrement traumatique, la relation de confiance est primordiale pour l’observance du traitement. Le suivi par une équipe pluridisciplinaire et la prise en compte d’éléments culturels peuvent éventuellement permettre une meilleure prise en charge.
La scolarité des élèves en situation de handicap : une « laïcisation » de l’autisme
Authors: Wacjman Claude
Published: November 2020

À partir des chiffres disponibles, on examine la situation des élèves en situation de handicap ainsi que les solutions qui leur sont proposées. À partir de ces informations on s’intéresse à l’augmentation de la prévalence dans les catégorisations officielles successives de l’autisme. La question de la marchandisation est étudiée sur le fond politique qui la caractérise par les orientations, les transformations de l’école, l’essor des activités privées et leur financement, les revendications des parents et de leurs associations.
L’éthique de la rencontre et le travail du fantasme dans la formation des enseignants en classe d’inclusion
Authors: Weber Jean-Marie
Published: November 2020

L’école inclusive constitue un énorme défi pour les enseignants au niveau psychique. Ce texte s’apprête à analyser le défi qui s’ouvre par la rencontre avec l’altérité. Par la présentations de différents extraits d’entretiens, il s’agira d’illustrer les difficultés des futurs enseignants encore en stage à se laisser altérer dans la rencontre avec des élèves à besoins spécifiques. C’est un travail de subjectivation, de déconstruction de leur fantasme qui est nécessaire pour accompagner les jeunes en souffrance. Etre à l’écoute de l’autre présuppose d’être à l’écoute de soi-même à travers l’autre. Vouloir rencontrer l’autre dans son altérité est un choix éthique.