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The thermal regime of underground mines, shaped by air temperature, velocity, and relative humidity, is a crucial factor for production and the health and safety of miners. While many aspects of this thermal regime have been thoroughly studied in the literature, local heat sources from mechanized equipment, such as load–haul–dump machines, conveyors, and auxiliary fans, have received comparatively little attention despite their significant impact on the thermal environment in mining development areas and stopes. This paper presents findings from a comprehensive study of the microclimatic air parameters in several nickel–copper and potash mines. We focus specifically on variations in air temperature in areas where mining equipment is operational. The heat output from different types of equipment, including load–haul–dump units, cutter–loaders, drilling rigs, conveyors, and auxiliary fans, has been quantified. We established empirical relationships for heat emissions from these machines and conducted a comparative analysis of their heat outputs. The main advantage of these relationships is their simplicity and the minimal number of input parameters required, making them practical for use in the field. [ABSTRACT FROM AUTHOR]

The thermal regime of underground mines, shaped by air temperature, velocity, and relative humidity, is a crucial factor for production and the health and safety of miners. While many aspects of this thermal regime have been thoroughly studied in the literature, local heat sources from mechanized equipment, such as load–haul–dump machines, conveyors, and auxiliary fans, have received comparatively little attention despite their significant impact on the thermal environment in mining development areas and stopes. This paper presents findings from a comprehensive study of the microclimatic air parameters in several nickel–copper and potash mines. We focus specifically on variations in air temperature in areas where mining equipment is operational. The heat output from different types of equipment, including load–haul–dump units, cutter–loaders, drilling rigs, conveyors, and auxiliary fans, has been quantified. We established empirical relationships for heat emissions from these machines and conducted a comparative analysis of their heat outputs. The main advantage of these relationships is their simplicity and the minimal number of input parameters required, making them practical for use in the field.

This article presents the impact of accuracy of sensors, or more specifically Pt100 temperature sensors, on result analysis of experimental studies. For this purpose, an experiment was carried out consisting in measuring the temperature on the surface of a partition - a concrete wall, beneath its insulation layer. The tested surface was separated from external environment and could only be influenced by the wall structure. Therefore, the expected result of the experiment, i.e. the difference in temperature sensor readings in identical locations on both sides of the partition, should reach a value close to 0. This article also presents the values of absolute error for sensors which were determined before their installation on the surface, and on which their location depended. The obtained deviations were included in the results of the experiment, which led to a decrease in temperature differences on both sides of the partition, in some cases even reaching the expected value of 0. This analysis showed how important it is to know the measurement error and then eliminate it in result interpretation. [ABSTRACT FROM AUTHOR]

Triply periodic minimal surfaces (TPMSs) show potential as porous materials in different engineering applications. Amongst them, heat sink is the subject of this paper. The advantage of such a structure is the ability to design it based on the intended applications. In the present paper, an attempt is made to experiment with a better understanding of the performance of TPMSs in heat sink applications. The experiment was conducted for different flow rates, and two heat sink materials, aluminum and silver, were used. In addition, two fluids were used experimentally: The first was water, and the second was a mixture of water containing 0.6% aluminum nanoparticles and identified as a nanofluid. The applied heat flux was maintained constant at 30,800 W/m2. The results reveal experimentally and confirm numerically that the TPMS structure secures a uniform heat extraction in the system. The development of the boundary layer in the porous structure is reduced due to the current structure design. A higher Nusselt number is obtained when the nanofluid is used as the circulating fluid. The performance evaluation criteria in the presence of the nanofluid exceed 100. [ABSTRACT FROM AUTHOR]

This manuscript focuses on the process of measuring the angular positions of radio sources using radio engineering systems. This study aims to improve the accuracy of measuring the angular positions of sources that radiate functionally determined signals and to expand the range of the unambiguous operation angles for multi-antenna radio direction finders. To achieve this goal, the following tasks were addressed: (1) defining the models of signals, noise, and their statistical characteristics, (2) developing the theoretical foundations of statistical optimization methods for measuring the angular positions of radio sources in multi-antenna radio direction finders, (3) optimizing the structures of radio direction finders with different configurations, (4) analyzing the accuracy and range of the unambiguous measurement angles in the developed methods, and (5) conducting experimental measurements to confirm the main results. The methods used are based on the statistical theory of optimization for remote sensing and radar systems. For the specified type of signals, given by functionally deterministic models, a likelihood function was constructed, and its maxima were determined for different multi-antenna direction finder configurations. The results of statistical synthesis were verified through simulation modeling and experiments. The primary approach to improving measurement accuracy and expanding the range of unambiguous angles involves combining antennas with different spatial characteristics and optimally integrating classical radio direction-finding methods. The following results were obtained: (1) theoretical studies and simulation modeling confirmed the existence of a contradiction between high resolution and the width of the range of the unambiguous measurements in two-antenna radio direction finders, (2) an improved signal processing method was developed for a four-antenna radio direction finder with a pair of high-gain and a pair of low-gain antennas, and (3) to achieve maximum direction-finding accuracy within the unambiguous measurement range, a new signal processing method was synthesized for a six-element radio receiver, combining processing in two amplitude direction finders and one phase direction finder. This work provides a foundation for further theoretical studies, highlights the specifics of combining engineering measurements in direction-finding systems, and offers examples of rapid verification of new methods through computer modeling and experimental measurements. [ABSTRACT FROM AUTHOR]

This article presents an analysis of thermal deformations in a large-scale vertical Lathe, examining the sources of heat and their impact on the machine's thermal deformations. The analysis was conducted using both experimental measurements and numerical simulations based on the finite element method. The study highlights the critical role of geometric accuracy, stiffness, and thermal distortions in machine tool design, affecting machining errors. Several machine tool manufacturers implement systems that minimize the impact of thermal distortions using numerical control. However, custom production lacks extensive possibilities, posing challenges in achieving requirements for predictable thermal distortions. This article analyzes the thermal distortions of a custom-produced machine tool and examines their values and consistency with the machine tool's working components' movement. The study emphasizes the predictability and directionality of thermal distortions in large-sized machine tools to maintain geometric accuracy and stiffness. Additionally, the study identifies non-technical aspects related to the division of the worktable into component parts, disrupting the axial symmetry of the construction and causing potential deformations of the workpiece due to thermal deformations. [ABSTRACT FROM AUTHOR]

The current study aims to develop new clay bricks doped with metallic waste for radiation shielding applications. The aforementioned new bricks were fabricated with various metallic waste concentrations under a pressure rate reaching ≈114 MPa and firing temperature of 1100 °C. The impacts of the metallic waste and the firing temperature on the developed brick samples' physical, radiation shielding, and structural properties were studied. In order to identify the fabricated bricks' mineral content, the X-ray diffraction pattern was used. Additionally, the fabricated bricks' porosity and density were experimentally determined, where the porosity was reduced by 28.03%, while their densities increased by ≈ 10.5% by raising the concentration of metallic waste. The linear attenuation coefficient (LAC) for the developed brick was investigated experimentally using a NaI (Tl) scintillation detector over the 0.033–1.408 MeV energy interval. The measured LAC values were enhanced by increasing the concentrations of metallic waste within the fabricated bricks over the examined energy interval. The fabricated brick's LAC enhancement improves the gamma-ray shielding characteristics. Therefore, the fabricated bricks are a cheap and suitable choice for radiation protection applications.

Background and Objectives: Manifestations of intermolecular interaction based on hydrogen bonding in hyaluronic acid IR spectra and in multicomponent mixtures of hyaluronic acid with nitrogen-containing amino acids, which are part of mucin of the mucous membrane of the bladder and protein carrier microgels, have been studied using experimental and theoretical IR spectroscopy. Materials and Methods: Comparison of measured and calculated hyaluronic acid IR spectra in harmonic approximation is performed. Calculations of molecular complexes structure and their corresponding IR spectra were carried out, followed by an analysis of the parameters of the hydrogen bonds formed. Results: Estimates of hyaluronic acid complexation with amino acids strength, which are part of protein microgels used in targeted therapy, and in target cells proteins were given. Conclusion: It has been found that the presence of an additional protein structure significantly increases the hyaluronic acid interaction with mucous membrane mucin protein due to intermolecular complexation based on polar basic amino acids.

This paper presents an investigation into the water permeability of an all-oxide ceramic matrix composite. To determine the parameters and characterize the water permeability of the ceramic composite material, an experimental study was carried out in which a dedicated test rig was constructed and commissioned. A total of five different configurations of composite tubes were tested. They differed in fibre roving strength, winding angle, fibre bundle arrangement during winding, and matrix grain size distribution. To better understand the internal structure of the analysed ceramic matrix composite material, the experimental study used scanning electron microscopy for microstructure and porosity observation. The tested tubes will be used as liners in an oxy-combustion chamber in future studies. The experiments obtained new and interesting results regarding the water permeability of the ceramic matrix composite with different structural parameters. It was also observed that, as with some porous materials, the permeability of ceramic matrix composites decreases with time as more and more liquid is pressed through it. [ABSTRACT FROM AUTHOR]

In this study, the focus is on investigating prevalent issues of rupture and wrinkling that occur during the extra-deep drawing process. These defects are very common in a local sanitary equipment industrial company, mainly in the manufacture of bathtubs, which increases scrap and leads to loss of time and costs in production. To analyze these defects, a numerical simulation of the bathtub extra-deep drawing process was performed with industrial parameters. The originality lies in controlling non-uniform blank holder pressures generated from six actuators in order to control the flow of the blank between the blank holder and the die and ensure the production of defect-free bathtubs. 3D and ultrasonic thickness measurements were performed on a bathtub manufactured without defects. Numerical and experimental plots of the thickness reduction show that the two approaches are in good agreement. The numerical results demonstrate that there are no rupture or wrinkling defects in the bathtub final shape, which exactly matches the actual case manufactured by the company. The numerical analysis was also performed on different cases that can cause rupture and wrinkling defects, namely: the influence of the blank holder pressure, the blank initial shape, and the die design using draw beads. [ABSTRACT FROM AUTHOR]

This paper investigates the model performance of an industrial box used to remove ammonia from the air using a doped activated carbon. To this end, process models are developed and experimental measurements are carried out. The models are based on momentum and mass balance equations along with thermodynamic, hydrodynamic and adsorption kinetic relations. The measurements consist of pressure drops in the air purification box and breakthrough curves of ammonia on activated carbon. The models are implemented and solved using COMSOL Multiphysics®. Adsorption is investigated by means of a Fickian multi‐scale model, which demonstrated to efficiently predict the experimental data. The optimal values of the most estimable unknown parameters involved in each model, as well as their confidence intervals are determined from experimental measurements. The performance of the industrial air purification model is rigorously assessed using statistical criteria, including mean‐square error (RMSE = 0.0013) and Pearson correlation coefficient (r = 0.999). [ABSTRACT FROM AUTHOR]

One of the significant processes that ensures realistic determination of the energy needs of historical buildings is case-specific definition of their local microclimatic conditions. Accordingly, the aim of this study is to determine differences for the parameters of temperature and humidity in urban and rural sub-settlements of the historical city, Muğla/Turkey. Study method consists of onsite measurements of these variables in sub-settlements for comparisons. As a result, it was identified urban zone shows heat island characteristics with warmer, drier, and more stable conditions; while rural sub-settlement remains cooler, more humid, and more erratic. In parallel, calculated extents of these differences demonstrate the significance and necessity of on-site measurements and consequential microclimatic zoning of historical cities as conservation/planning tools for responding to the thermal needs of architectural heritage. A key application of these processes would be the establishment of local databases of case-specific weather data to be used in thermal simulation assessments. [ABSTRACT FROM AUTHOR]

A unique brick series based on Vietnamese clay was manufactured at 114.22 MPa pressure rate for γ-ray attenuation purposes, consisting of (x) metallic waste & (90%-x) red clay mineral & 10% (hardener mixed with epoxy resin), where (x) is equal to the values 0%, 20%, 40%, 50%, and 70%. The impacts of industrial metal waste ratio in the structure and radiation protective characteristics were evaluated experimentally. The increase in metallic waste doping concentrations from 0% to 70% was associated with an increase in the manufactured brick's density (ρ) from 2.103 to 2.256 g/cm3 while the fabricated samples' porosity (Φ) decreased from 11.7 to 1.0%, respectively. Together with a rise in fabricated brick's density and a decrease in their porosities, the manufactured bricks' γ-ray attenuation capacities improved. The measured linear attenuation coefficient (μ, cm−1) was improved by 30.8%, 22.1%, 21.6%, and 19.7%, at Eγ equal to the values respectively 0.662, 1.173, 1.252, and 1.332 MeV, when the metallic waste concentration increased from 0% to 70%, respectively. The study demonstrates that manufactured bricks exhibit superior radiation shielding properties, with radiation protection efficiencies of 88.4%, 90.0%, 91.7%, 92.1%, and 92.4% for bricks with industrial metal waste contents of 0%, 20%, 40%, 50%, and 70%, respectively, at γ-ray energy (Eγ) of 1.332 MeV.

In this paper, we develop a finite-difference time-domain (FDTD) model in which the time-evolving electrical conductivity of the air ionization plasma in DC voltage needed-plate setup is represented. Maxwell's equations are solved using the FDTD method, and the associated currents and discharge fields are computed over time and in three-dimensional space. The proposed model for the electrical conductivity is dependent on time, the applied DC voltage, and the gap length. The necessary data for developing the proposed model is obtained experimentally using a standard discharge needle, with its spherical tip measuring approximately 40 μ m in diameter. Once high voltage is applied, a steady state is achieved. The electrical conductivity σ (t) and its associated parameters are then calculated using nonlinear equations proposed to reproduce the experimentally obtained plasma behavior in the full-wave FDTD model. Voltage ranges from 4 kV to 9 kV, and gap distances are between 4 mm and 8 mm. [ABSTRACT FROM AUTHOR]

This article concentrates on the numerical analysis of hydration heat resulting in formation of cracks on the experimental block of the spillway at Orlik Reservoir and its verification with the experimental measurement. In order to eliminate the maximum of critical factors which could lead to appearance of early age cracking and faulty execution of the spillway, an experimental block was concreted. It served as a trial block for all steps of the execution process as well as a validating temperature measurement during cement hydration to confirm with the preliminary numerical analysis. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to investigate the hydrodynamic and vibrational behavior of the 2000 mm diameter Howell Bunger valve that will be installed in the Khodaafrin dam. The existence of a historical bridge downstream of this dam makes it important to investigate the vibration and hydrodynamic behavior of the valve, so that its design and operation should be in such a way that the historical bridge located downstream will not be damaged. In order to achieve this goal, the valves are considered to have submerged discharge, and this has raised the need to investigate the hydrodynamic behavior of the valve and compare it with the non-submerged state. To investigate the behavior of the valve, a 1:20 model of the valve, hood and discharge pool were designed and built. Then, the experimental rig was designed and equipped with measuring equipment, and the model valve was subjected to hydrodynamic and vibration tests with different opening percentages in non-submerged and submerged states with different downstream pool depths. These experiments have been repeated for the valve with hood and without hood and the results have been compared. Then, the finite element model of the 1:20 model valve was developed and hydrodynamically analyzed and the numerical results were compared with the experimental data. After ensuring the correctness of the numerical model, it was used to investigate the behavior of the valve in different conditions. The results show that there is not much change in the flow rate when the valve is submerged, but the range of vibrations decreases significantly. This decrease in the amplitude of vibrations becomes more dominant with increasing the depth of the pool. Also, it has been shown that the range of vibrations in the case without the hood is lower than the case with the hood. [ABSTRACT FROM AUTHOR]

To improve building energy efficiency and address thermal storage challenges during periods without a heat source, such as cloudy weather or night-time, a range of solutions is required. Innovative technologies and sustainable practices are essential for combating climate change and reducing carbon emissions. This study primarily focuses on Thermal Energy Storage (TES) systems, specifically those using Phase Change Materials (PCMs), to increase energy efficiency for Transpired Solar Collectors used in buildings applications. During the last 30 years Transpired Solar Collectors (TSC) have been extensively investigated. However, a primary concern still exists regarding thermal storage when the heat source is unavailable, such as during periods of cloudy weather or at night. Thus, a Thermal Energy Storage (TES) system coupled with the TSC is a potential solution. In this study we are investigating using numerical simulation the arrangement of encapsulation for TES, integrating phase change materials (PCM) in spherical elements when compared with plate encapsulation elements. The model reproduces a part of a real scale thermal energy storage inserted in a Double Skin TSC. The model consists of a Plexiglas duct in which four different arrangements for the spherical encapsulated PCM were studied. For each of the arrangements the heat transfer between the TES elements and the air passing through the collector was analyzed. The primary finding of the study indicates that the hexagonal arrangement offers better passive airflow control, thus enhancing the heat transfer up to 12.3% compared to the rectangular arrangements [ABSTRACT FROM AUTHOR]

The present study investigated experimentally the dynamic interactions between surface waves and submerged vertical tensioned barriers with full and partial penetrations. The range of tension for the barrier was set within the flexible membrane regime in the experiments which measurements have not been reported in the literature so far. In addition, an extensive Internet of Things (IoT) system with five GoPro cameras was developed for the measurements to quantify both the surface wave transformation as well as dynamic response of the barrier. The cameras were synchronized through the IoT system to cover the entire wave flume, and the recorded videos were converted to spatial and temporal data using image processing techniques. The experimental results were found to agree with the analytical predictions based on the linear wave theory reasonably well. In particular, the measured reduction in the tensioning effect on the wave transmission and reflection with decreased barrier length was in close argument with the predictions. Similar good agreement was also observed for the dynamic response of the tensioned barrier during the wave interaction. However, additional energy loss was noted in the experiments possibly due to energy dissipation at the boundary ends of the experimental barrier and wave-induced flow separation with partial penetration which are not considered in the analytical analysis. [ABSTRACT FROM AUTHOR]

Current building envelope greening systems are not just areas covered with vegetation. Today's systems can maximise the functional contribution of vegetation to a building's performance and become part of a sustainable urban renewal strategy. The impact of the vegetation layer directly affects the building in its immediate vicinity, from the outside, while also having a significant impact on the indoor environment. Green roofs are the most widespread vegetated structures worldwide. This paper aims to demonstrate the behaviour of the temperature regime of an extensive green roof over a production hall and an administrative area in comparison to that of a roof without vegetation cover. In evaluating the results, a period with weather representative of winter and summer was selected to show the importance of seasonality. The fact that this is a new building, and that the extensive roof is not fully covered with vegetation, is very well reflected in the results, as the absence of a vegetated area significantly affects the temperature of as well as the heat flux through the roof structure. The dark colour of the substrate absorbs significantly more solar radiation than the light surface of the waterproofing, resulting in an increase in temperature and heat flux into the structure. [ABSTRACT FROM AUTHOR]

A method is proposed for uniform approximation of a deformed grid so as to reduce the influence of distortions due to random and systematic errors in determining the coordinates of the grid points. As an illustration, this method is used to assess the strain in extrusion through a channel whose cross section varies in shape. [ABSTRACT FROM AUTHOR]

This paper discusses experimental and simulated data regarding the thermal bridging effect in a reinforced concrete corner pillar, which belongs to a building dating back to the 1980s and located in Southern Italy. The thermal field determined by the concrete pillar corner has been evaluated, introducing an experimental procedure based on both direct measurements and indirect observations of the inner superficial temperature by means of thermal imaging techniques and surface temperature probes. Moreover, indoor and outdoor air temperature and relative humidity were measured to provide suitable boundary conditions in the numerical simulations, performed with a commercial software tool widely used in Italy based on 2D finite element techniques. The experimental measurements show that, at more than 50 cm from the corner, the surface temperatures become almost constant, meaning that the thermal bridging effect becomes less evident. However, the surface temperature in the corner is around 1.5 °C lower than in the undisturbed flanking walls. In terms of local heat flux, the discrepancy between simulations and measurements is below 3%. Finally, this paper verifies the effectiveness of External Thermal Insulation Composite System (ETICS) renovation in reducing the thermal bridging effect of the corner pillar. The results also include the calculation of the linear thermal transmittance with a series of relations available in well-known atlases for thermal bridges and show that these relations are more reliable in the case of uninsulated pillar than for the insulated one. [ABSTRACT FROM AUTHOR]

This article concentrates on the numerical analysis of hydration heat resulting in formation of cracks on the experimental block of the spillway at Orlik Reservoir and its verification with the experimental measurement. In order to eliminate the maximum of critical factors which could lead to appearance of early age cracking and faulty execution of the spillway, an experimental block was concreted. It served as a trial block for all steps of the execution process as well as a validating temperature measurement during cement hydration to confirm with the preliminary numerical analysis.

Beamforming and massive multiple-input-multiple-output (mMIMO) technologies are key features of base stations (BSs) in the fifth-generation (5G) of mobile networks. This technology is used to focus more radio frequency (RF) energy towards actively connected users to improve their connection/performance, resulting in high variations in the radio frequency electromagnetic fields (RF-EMFs). This paper proposes a new methodology for modelling the RF-EMF exposure for 5G new radio (NR) mMIMO BS by means of a physics-informed machine learning (ML) approach using empirical measurement data. More precisely, the main focus of our work is to develop a suitable traceable RF-EMF exposure prediction tool in the context of 5G mMIMO BSs that can serve multiple mobile users (i.e. multiple-user MIMO (MU-MIMO)) within realistic real-world environments and scenarios. Our RF-EMF prediction tool relies on empirical measurement data acquired via a user-controllable mMIMO beamforming testbed and traceable RF-EMF measurement capability, where both indoor and outdoor RF-EMF measurement campaigns have been carried out. During the measurement campaigns various factors such as number of users, position of users and data duty cycles were considered. Using an ensemble of gradient boosted decision trees, we show that a physics-informed approach can improve predictive performance of RF-EMF compared with a purely data-driven approach, with the ability to extrapolate values of RF-EMF exposure to larger distances. Results show a coefficient of determination value of 0.86 on a 10-fold cross-validated experimental dataset. We also compare the sensitivity of RF-EMF exposure to various factors in the model, and show that model predictions become isotropic for large numbers of beam configurations, simplifying the exposure measurement methodology of 5G systems.

Triply periodic minimal surfaces (TPMSs) show potential as porous materials in different engineering applications. Amongst them, heat sink is the subject of this paper. The advantage of such a structure is the ability to design it based on the intended applications. In the present paper, an attempt is made to experiment with a better understanding of the performance of TPMSs in heat sink applications. The experiment was conducted for different flow rates, and two heat sink materials, aluminum and silver, were used. In addition, two fluids were used experimentally: The first was water, and the second was a mixture of water containing 0.6% aluminum nanoparticles and identified as a nanofluid. The applied heat flux was maintained constant at 30,800 W/m2. The results reveal experimentally and confirm numerically that the TPMS structure secures a uniform heat extraction in the system. The development of the boundary layer in the porous structure is reduced due to the current structure design. A higher Nusselt number is obtained when the nanofluid is used as the circulating fluid. The performance evaluation criteria in the presence of the nanofluid exceed 100.

This manuscript focuses on the process of measuring the angular positions of radio sources using radio engineering systems. This study aims to improve the accuracy of measuring the angular positions of sources that radiate functionally determined signals and to expand the range of the unambiguous operation angles for multi-antenna radio direction finders. To achieve this goal, the following tasks were addressed: (1) defining the models of signals, noise, and their statistical characteristics, (2) developing the theoretical foundations of statistical optimization methods for measuring the angular positions of radio sources in multi-antenna radio direction finders, (3) optimizing the structures of radio direction finders with different configurations, (4) analyzing the accuracy and range of the unambiguous measurement angles in the developed methods, and (5) conducting experimental measurements to confirm the main results. The methods used are based on the statistical theory of optimization for remote sensing and radar systems. For the specified type of signals, given by functionally deterministic models, a likelihood function was constructed, and its maxima were determined for different multi-antenna direction finder configurations. The results of statistical synthesis were verified through simulation modeling and experiments. The primary approach to improving measurement accuracy and expanding the range of unambiguous angles involves combining antennas with different spatial characteristics and optimally integrating classical radio direction-finding methods. The following results were obtained: (1) theoretical studies and simulation modeling confirmed the existence of a contradiction between high resolution and the width of the range of the unambiguous measurements in two-antenna radio direction finders, (2) an improved signal processing method was developed for a four-antenna radio direction finder with a pair of high-gain and a pair of low-gain antennas, and (3) to achieve maximum direction-finding accuracy within the unambiguous measurement range, a new signal processing method was synthesized for a six-element radio receiver, combining processing in two amplitude direction finders and one phase direction finder. This work provides a foundation for further theoretical studies, highlights the specifics of combining engineering measurements in direction-finding systems, and offers examples of rapid verification of new methods through computer modeling and experimental measurements.

This work presents a comparison of two-dimensional numerical solutions of unsteady free surface flow. This is a simulation of the dam-break wave with different configurations using based-mesh finite volume method and meshless smoothed particle hydrodynamics (SPH). Two well-known approaches, widely used in the computational fluid dynamics (CFD). These techniques have proven their robustness in the numerical treatment of such conservation laws. The main goal is to check the ability of the SPH method and the first order finite volume HLLC solver to reproduce the numerical solutions of the 2D shallow water equations. Based on many benchmark tests, one investigates the effect of the topographic variation along the x and y directions on behavior of the numerical solutions namely at the wet-dry front. The comparison between the simulated results, the analytical solutions and the experimental measurements shows a good correlation, although the finite volume approach remains more advantageous in terms of accuracy and the CPU time.

Membrane electrode assemblies (MEA) are composed of five principal layers: two gas diffusion layers on top of two catalyst layers surrounding the membrane. The understanding of the mechanical behavior at the different interfaces of the MEA is therefore essential and will be the subject of this study through the development of a new methodology to evaluate the friction coefficients between the different layers. The analysis of the MEA components and their assembly process impact will be considered. A morphological analysis based on confocal microscopy observations of the catalyst layer/microporous layer interface was conducted to evaluate the roughness of the different surfaces submitted to friction. Results show that the static friction increases with the addition of microporous layers and catalyst layers on their substates. The friction coefficients also increase after a low pressure hot pressing but they surprisingly decrease after an assembly performed at a high pressure. [Display omitted] • A new method is developed to measure the friction coefficient of MEA interfaces. • The influence of the MEA material and process on the friction coefficient is analyzed. • Morphological analysis of the surfaces of the MEA component were performed. • Hot-pressing step allows to tune the mechanical properties of MEA interfaces. [ABSTRACT FROM AUTHOR]

This research analysis is mainly devoted to enhancing the safe and optimum use of the Center des Etudes Nucléaires de la Maâmora (CENM) TRIGA MARK II research reactor. To serve this purpose, various integral neutronic responses, such as the effective multiplication factor keff, the effective delayed neutron fraction βeff, the neutron flux distributions at the beam port entrances and the pneumatic transfer system bottom, the pin power peaking factors, the total excess reactivity, the control rod worth, the shutdown margin, and the worth of 11 fuel elements taken from different TRIGA core positions are calculated in order to evaluate the accuracy and the reliability of the developed TRIGA SCALE reactor model. The aim has been fulfilled by comparing the TRIGA SCALE results with those obtained by the MCNP TRIGA model, as well as with some recent experimental measurements from 2021. In general, all the obtained results reveal a good consistency between the SCALE and MCNP TRIGA models studied in this paper. The results analysis indicates also that the B-2 fuel element (Ring B) is the hottest rod among the 101 fuel rods existing in the TRIGA reactor core, which releases a maximum power of 31.67 kW. Furthermore, the total control rod worth, the total core excess reactivity, and the shutdown margin results are also closer to the experimental measurements. [ABSTRACT FROM AUTHOR]

There exists a high level of difficulty in understanding the physical responses of complex dynamical systems. To this end, researchers have previously used different measurement techniques, such as displacement sensors or accelerometers, in the laboratory to capture a system's dynamics. A well-known structure in the literature is the Box Assembly with Removable Component (BARC) whose purpose is to gain a deep understanding of testing complex systems. Further breaking down the structure, the Removable Component (RC) portion is often used as a relatively simplified version which retains significant complexity from the original system. However, the placement of accelerometers on the RC have varied greatly throughout the literature which presents a challenge in comparing results and may not accurately represent the system's dynamics. Finite Element Analysis (FEA) is performed for three common accelerometer locations to determine how their placement affects the frequencies and mode shapes for the RC and results are compared against those without accelerometers. Free vibration experiments are carried out to understand the variation of frequencies and damping for each accelerometer location to obtain the overall response for the first mode of vibration. Next, random vibration experiments are run to gain insight on the interaction between linear and nonlinear responses based on excitation level, while showing the influence of an accelerometer's location on system dynamics. The results demonstrate that the location of the accelerometer is highly influential on the linear and nonlinear characteristics of the system. It is proved that for the first mode of vibration, nonlinear softening and nonlinear damping behaviors may take place due to the interaction between the location of accelerometers, direction of excitation, and response axis analyzed. [ABSTRACT FROM AUTHOR]

The realistic simulation of the dynamic responses of a moving articulated vehicle has attracted considerable attention in various disciplines, with the identification of the vehicle model being the prerequisite. To this end, a double-sensor hump calibration method (DHCM) was developed to identify both unladen and laden vehicle models, consisting of a sensor layout optimization step and a system identification step. The first step was to optimize the number and position of sensors via parameter sensitivity analysis; the second was to inversely identify the vehicle system based on sensor responses. For comparison, the DHCM and the existing single-sensor hump calibration method (SHCM) were used to calibrate a small-sized vehicle model and a multi-axle articulated vehicle model. Vertical accelerations of the vehicle models were then simulated and characterized by power spectral densities (PSDs). Validation against experimental measurements indicated that the PSDs of the models identified with the DHCM matched the measured PSDs better than those of the SHCM, i.e., the DHCM-identified model accurately simulated the dynamic response of an articulated vehicle with relative errors below 16% in the low-frequency range. Therefore, the DHCM could identify models of small-sized vehicles and multi-axle articulated vehicles, while the SHCM was only suitable for the former. [ABSTRACT FROM AUTHOR]

In the unfortunate event of a fire, within the context of the evolution of façade fires, with a specific focus on the utilization of polystyrene thermal insulation (external thermal insulation composite system façades—ETICS façades), this study delves into the investigation of fires ignited by containers containing plastic bottles. Through an examination of the fluctuating temperatures within the affected room and its adjacent areas, as well as an assessment of the fire's impact on polystyrene thermal insulation, this paper underscores the significance of incorporating non-combustible barriers into the building's thermal insulation system. The tests conducted revealed that the temperature inside the room reached a maximum of 1100 °C, subsequently decreasing to 800 °C at a height of 2.5 m and approximately 400 °C at a height of 5 m. For this research, two 1100-L containers of household waste were employed, each weighing 45.5 kg and possessing a gross calorific value of 46.97 MJ/kg, with 10.7 kg of PET bottles inside, characterized by a higher calorific value of 23.90 MJ/kg as the source of the fire. Heat release rate highest values were obtained between 11 and 17 min, with a maximum value of 4919 kW. Thus, even in the absence of specific legislation, this study emphasizes the imperative need to establish safety distances for the storage of household waste away from the building's façade to mitigate the risk of fire propagation, particularly in relation to materials such as polystyrene thermal insulation. Furthermore, in certain situations, extensive fire experiments on a grand scale, like the one undertaken in this research, hold a crucial position in confirming numerical findings for global researchers. This process assures the reliability and real-world usefulness of fire safety studies through the experimental outcomes presented in this investigation. [ABSTRACT FROM AUTHOR]

In Tabula XCI verso of Codex Atlanticus, Leonardo da Vinci presents an ingenious masonry structure composed of segments in the shape of inverted triangles. These are assembled by contact in a chain to obtain a lintel or jack arch, where they are pressed together by the thrust of the end constraints. Drawing inspiration from Leonardo's sketches, we show that, by connecting the segments in pair through elastic tendons, this system represents a new type of flextegrity beam. In a classical flextegrity, the contact surfaces of the segments are curved conjugate profiles, imposing a pure rolling motion along properly designed pitch lines: the consequent elongation of the tendon dictates the constitutive response as a function of the relative rotation of the segments. Here, the contact is through plane surfaces, so that the kinematics, besides the relative rotation, is characterized by segmental shearing. This system is theoretically analysed and a continuum model is derived as the length of the segments becomes small. Comparisons with experiments on three-dimensional-printed prototypes confirm the theoretical findings and highlight the possible competition between rotational and sliding types of deformation. Apart from the historical value, this type of construction can be used in innovative structures or metamaterials. [ABSTRACT FROM AUTHOR]

This contribution investigates the vertical coupling exerted by ballasted tracks on the vertical response of bridges composed either of (i) several successive simply-supported spans with weak coupling between them due to the continuous track; or (ii) adjacent single-track decks conforming a double-track bridge, in which interaction effects are induced due to the transverse continuity of the ballast layer. To this end, 2 D and 3 D track-bridge interaction Finite Element models are implemented, which consider a three-layer discrete and explicit idealization of the track. The 2 D track-bridge interaction model is used to perform sensitivity analyses on the track parameters, which have revealed that the ballast shear mechanisms along the track may significantly affect the train-induced vibrations under resonant conditions. Then, the influence of the ballast coupling on the response of twin adjacent decks is investigated with a 3 D track-bridge interaction model. To this end, this model is updated based on the results of an experimental campaign performed on a real bridge composed of two SS spans and two single track twin adjacent decks. The numerical-experimental comparison shows an evident dynamic vertical coupling between the bridge decks and reveals the importance of including the ballasted track in the modelling process of these structures. [ABSTRACT FROM AUTHOR]

The design of a 69 m tall multipurpose building was investigated in this paper. The shape of the structure above the ground was an elliptical cylinder. Under the ground, the building was extended into a cuboid shape (for car parking). External wind pressure coefficients were determined using three methods: wind tunnel tests, CFD, and "the simplification of the shape" (using information defined in building standards). From the obtained results, it was evident that the simplification did not provide results with sufficient accuracy. The external wind pressure coefficients presented in this paper should be used for the design of a similar structure. The shape of the elliptical cylinder is very sensitive to applied wind. Positive pressures only occur on a small area of the windward side. The rest of the windward side is loaded with negative pressures. Therefore, torsional effects can occur, and these can be dangerous for the structure. The leeward side is completely loaded with negative pressures. In our case, this information was necessary for a follow-on static and dynamic analysis of the building. Various subsoil stiffness coefficients were considered. The calculated horizontal displacement was compared with the limit value. A measured wind direction of 20° caused the maximum obtained torsional moment, and a wind direction of 90° induced the maximum obtained force. The commercial program Ansys Fluent 2022 was used for the CFD simulation. The SCIA ENGINEER 21 program was used for follow-on analysis. This paper presents brief information on the selected turbulence model and details the settings used for the CFD simulation. Also, a description of the wind tunnel laboratory utilized in this study is provided, along with a description of the measuring devices used and the methodologies of the tests carried out. The main purpose of this paper is to show how important it is to consider the wind load for the static analysis of a structure like this. [ABSTRACT FROM AUTHOR]

One of the most important parameters when it comes to heat losses in buildings is the thermal transmittance or U-value. Therefore, great importance should be given to the determination of U-values, especially for elements where there is a high thermal bridge effect, as is the case with lightweight steel frame (LSF) structures. Since LSF structures are usually geometrically more complex, especially when diagonal elements are present, the determination of the overall U-value of these elements is usually done either on scale models in the laboratory or by numerical methods. This paper compares different methods for determining the total U-value for four different polyurethane foam-filled LFS walls and a reference wall made of EPS. Analytical (ISO 6946), experimental (Guarded Hot Box Method and HFM) and numerical 2D and 3D calculations were used to determine the U-value. The aim of the comparison was to verify which methods can be used for more complex geometries of LSF walls when there is a stronger influence of point thermal bridges due to the additional diagonal bracing. All methods showed similar U-values with the highest absolute deviation of 17.18% between the HFM and the 3D numerical calculations. The analytical method for inhomogeneous building elements given in ISO 6946 agrees well with all methods with the maximum absolute deviation of 8.83% between the analytical and HFM method. The work showed the importance of the placement of the HFM sensor for the determination of the surface heat flux, as incorrect placement of the sensor can result in inadequate U-values that deviate up to 167% from the true value.

We present a synergistic investigation into ozone production dynamics within a high-voltage reaction chamber operating from 1.75 kV to 10 kV, at 60 Hz. The output ozone concentration dependence on a 60 Hz root mean square high-voltage for an air input pressure of 0.1 bar was measured using an ultraviolet-based sensor. A finite-element numerical model of the reaction chamber was developed and used for obtaining the reaction rate for the generated ozone for each level of input voltage and the internal distribution of the gas vector velocity field and ozone concentration. An expression to estimate the ozone reaction rates from the measured ozone concentrations was also derived. It was then compared and validated using the developed computational model. Therefore, in this work, a formula is proposed to estimate the ozone production by providing the experimental reaction rates. The other objective is to analyze the hysteresis phenomena observed in the partial discharges' levels in the reaction chamber and in the output ozone concentration. Finally, we establish a connection between the total power of partial discharges and the consequent ozone production, clarifying the role of cumulative partial discharges' power levels in governing the resultant output ozone concentration. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional (3D) numerical model based on the finite element method (FEM) is developed to determine the fluid flow and heat transfer phenomena in a real multi-tube downhole heat exchanger (DHE), designed ad hoc for the present application, considering natural convection inside a geothermal reservoir. The DHE has been effectively installed and tested on the island of Ischia, in southern Italy, and the measurements have been used to validate the model. In particular, the authors analyze experimentally and numerically the behavior of the DHE based on the outlet temperature of the working fluid, thermal power, overall heat transfer coefficient, and efficiency. Furthermore, the influence of the degree of salinity on the performance of the DHE has been studied, observing that it degrades with the increase in the degree of salinity. The results show that the DHE allows to exchange more than 40 kW with the ground, obtaining overall heat transfer coefficient values larger than 450 W/m2 K. At the degree of salinity of 180 ppt, a decrease in the efficiency of the DHE of more than 8% is observed. [ABSTRACT FROM AUTHOR]

Experimental data are presented on pressure variation rate during the combustion of a coal dust particle–air mixture in a closed spherical volume at various mass concentrations of coal dust. A physical-mathematical model of the combustion of a coal dust particle–air mixture in a closed spherical volume is formulated on the basis of equations of mechanics of dispersed media in a one-velocity one-temperature approximation. The combustion wave propagation velocity relative to a gas suspension and the burning rate of a coal dust particle are model parameters determined by matching computational results with experimental data. There is good agreement between them. The proposed approach can be used to assess the effect of coal dust combustion on shock wave intensity in coal mines during accidental methane explosions involving coal dust. [ABSTRACT FROM AUTHOR]

Although GFRP poles are widely accepted today due to their low cost and weight and high electrical and corrosion resistance, they suffer large deformations due to the low elastic and rigidity moduli (E & G) values of the GFRP. Accordingly, it is essential to accurately measure these values to estimate the actual deformation of the pole. This study presented a procedure to measure (E & G) values using three different tests on three sample sizes: full, scale pole, conic sample, and ad coupon sample, instead of using the manufacturer values as usual. This study is also concerned with the shear modulus value and when it can be neglected as usual in other traditional materials. The GRG optimization technique was used to analyze the results and determine the optimum values for (E & G) considering the results of the three tests. The results showed that the values of (E & G) are greatly affected by the sample's size and shape, the slenderness ratio of the sample (L/r), and the shear deformation contribution. The critical slenderness ratio (L/r), corresponding to a shear deformation contribution of 10%, was determined for each test. This value is recommended as the upper boundary for any test that measures the (E & G) values. Testing several samples with different (L/r) values is also recommended to enhance accuracy. This study was concerned with determining the optimum values of elastic and rigidity moduli for GRFP poles compared to the manufacturer's conservative values. The results indicated that the shear modulus can be neglected and the importance of the scale effect on the results of flexure and shear modulus. [ABSTRACT FROM AUTHOR]

Providing reliable connectivity to cellular-connected Unmanned Aerial Vehicles (UAVs) can be very challenging; their performance highly depends on the nature of the surrounding environment, such as density and heights of the ground Base Stations (BSs). On the other hand, tall buildings might block undesired interference signals from ground BSs, thereby improving the connectivity between the UAVs and their serving BSs. To address the connectivity of UAVs in such environments, this paper proposes a Reinforcement Learning (RL) algorithm to dynamically optimise the height of a UAV as it moves through the environment, with the goal of increasing the throughput or spectrum efficiency that it experiences. The proposed solution is evaluated in two settings: using a series of generated environments where we vary the number of BS and building densities, and in a scenario using real-world data obtained from an experiment in Dublin, Ireland. Results show that our proposed RL-based solution improves UAV Quality of Service (QoS) by 6% to 41%, depending on the scenario. We also conclude that, when flying at heights higher than the buildings, building density variation has no impact on UAV QoS. On the other hand, BS density can negatively impact UAV QoS, with higher numbers of BSs generating more interference and deteriorating UAV performance.