Accurate cutting-force measurements appear to be the key information in most of the machining related studies as they are fundamental in understanding the cutting processes, optimizing the cutting ...operations and evaluating the presence of instabilities that could affect the effectiveness of cutting processes. A variety of specifically designed transducers are commercially available nowadays and many different approaches in measuring cutting forces are presented in literature. The available transducers, though, express some limitations since they are conditioned by the vibration of the surrounding system and by the transducer׳s natural frequency. These parameters can drastically affect the measurement accuracy in some cases; hence an effective and accurate tool is required to compensate those dynamically induced errors in cutting force measurements. This work is aimed at developing and testing a compensation technique based on Kalman filter estimator. Two different approaches named “band-fitting” and “parallel elaboration” methods, have been developed to extend applications of this compensation technique, especially for milling purpose. The compensation filter has been designed upon the experimentally identified system׳s dynamic and its accuracy and effectiveness has been evaluated by numerical and experimental tests. Finally its specific application in cutting force measurements compensation is described.
•Cutting force measurements can be drastically affected by machine tool dynamics.•Dynamic compensation can extend the bandwidth of commercial dynamometers.•Two different approaches suitable for milling applications have been developed.•The effectiveness of the proposed approaches has been experimentally evaluated.•Examples in cutting force measurements compensation are shown.
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.
Abstract
In this paper, an efficient method is proposed for detecting and locating a soft fault, i.e. a physical degradation, in a
Y
-shaped network of unshielded twisted pair cables. The method uses ...jointly the observability analysis and time-frequency domain reflectometry experimental measurements. The fault detection consists in checking the consistency between the known characteristics of the cable under no-fault and faulty conditions, with the maximum value of a normalized time-frequency cross-correlation function computed on a sliding time window whose length is equal to the boundary exact observability time. The cable transmission speed and the wired network observability time are combined to locate precisely the fault. Soft faults are artificially created by connecting resistors of different values to the test cable. Experimental results show the efficiency of our fault detection and localization method.
Energy Recovery Ventilators (ERVs) using semi-permeable membranes are widely used in buildings to improve indoor air quality and reduce energy consumption. These membranes are pretensioned but can ...deflect under the influence of inlet and flow-induced pressure differences. We measure the impact of membrane deflection on pressure drop, flow distribution, and thermal performance of a commercial crossflow ERV. A modest applied pressure differential and the resulting membrane deflection can cause significant variations in pressure drop along each flow path. The membrane deflections can cause the pressure drop along the channels to vary by up to a factor of two, depending on the inlet pressure differential. The ERV's sensible effectiveness decreases from 70.4% to 67% as the inlet pressure differential increases from −0.85 to +0.85 in·H2O (+211.5 Pa). A numerical model is proposed to determine the deflection pattern in an ERV. The model is validated against experimental data and is consistent with experiments to within an RMS error of 0.15 and 0.08 in·H2O (37.3 and 19.9 Pa), which corresponds to approximately 15% and 8% of the pressure drop under typical working conditions of the exchanger. However, the model is not able to capture the change in thermal effectiveness, which may originate from the texturing of the deflected membrane, which is not included in the model.
•Energy-efficient solution for stabilising thermal comfort conditions in modern buildings in both heating and cooling modes.•Thermal and flow characteristics of the U-groove radiant panels in a test ...chamber were investigated.•The numerical model to predict the temperature in a room with the cooling and heating panels installed was developed.•The numerical model can be used to design heating and cooling radiant ceilings.
Thermally activated panels with monolithic structure and complex shape are not known well. Additionally, studies of radiant heating–cooling panels described in the literature mainly focus on either cooling or heating as well as either ceiling or wall option. In this paper, a novel heating and cooling panel with a U-groove surface and aluminium monolithic structure that increases heat exchange between the heating–cooling medium and the panel was studied. The performance of a new panel for the wall and ceiling options was investigated experimentally. For this analysis, an extended study was carried out that included both heating and cooling modes to develop a universal solution. A numerical model to predict the temperature in a room with the cooling and heating panels installed was developed and compared with experimental results. The specific thermal capacity of the panels observed in the experiments ranged from 82 to 158 W/m2, sufficient to maintain thermal comfort in modern buildings that meet low-energy or passive building standards. The specific cooling capacity of the studied panels ranged from 47 to 59 W/m2, similar to high-temperature radiant cooling systems used in modern buildings. The investigated panels are compatible with mechanical ventilation systems equipped with a cooling function. The simulation results were in agreement with the experimental measurements. Thus, the numerical model can be used to design heating and cooling radiant ceilings as well as to assess thermal conditions in a room.
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.
For 662, 1173, 1275, and 1333 keV gamma-ray energy, photon transmissions, linear attenuation coefficients, half value layer, tenth value layer, and mean free path values of bismuth-borophosphate ...glasses were measured experimentally. Then, the measured findings were compared to the FLUKA code. The FLUKA code findings agreed well with the experimental results. Furthermore, the findings show that adding Bi2O3 to the glass network improves the shielding properties. The current data reveal that when the Bi2O3 content rises, so does the absorbance. Furthermore, the optical constants of the present gasses, such as optical band gap, phonon energy, and tails of localized states, were examined. Fourier transform infrared (FTIR) spectrometer was used to analyze the Fourier transform infrared (FTIR) spectra of our samples at room temperature in the 4000–400 cm−1 wavenumber range. From a shielding standpoint, bismuth-borophosphate glasses offer excellent gamma-ray shielding properties.
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 reports on an ongoing international effort to establish guidelines for numerical modeling of wave energy converters, initiated by the International Energy Agency Technology Collaboration ...Program for Ocean Energy Systems. Initial results for point absorbers were presented in previous work, and here we present results for a breakwater-mounted Oscillating Water Column (OWC) device. The experimental model is at scale 1:4 relative to a full-scale installation in a water depth of 12.8 m. The power-extracting air turbine is modeled by an orifice plate of 1–2% of the internal chamber surface area. Measurements of chamber surface elevation, air flow through the orifice, and pressure difference across the orifice are compared with numerical calculations using both weakly-nonlinear potential flow theory and computational fluid dynamics. Both compressible- and incompressible-flow models are considered, and the effects of air compressibility are found to have a significant influence on the motion of the internal chamber surface. Recommendations are made for reducing uncertainties in future experimental campaigns, which are critical to enable firm conclusions to be drawn about the relative accuracy of the numerical models. It is well-known that boundary element method solutions of the linear potential flow problem (e.g., WAMIT) are singular at infinite frequency when panels are placed directly on the free surface. This is problematic for time-domain solutions where the value of the added mass matrix at infinite frequency is critical, especially for OWC chambers, which are modeled by zero-mass elements on the free surface. A straightforward rational procedure is described to replace ad-hoc solutions to this problem that have been proposed in the literature.
Double hearing protectors (DHPs), earplugs and earmuffs worn in combination, may be needed in high level noise environments. The DHP sound attenuation is known to be less than the sum of each single ...protector attenuation. This effect, referred to as the DHP effect, is still not fully understood. A recent study has shown that it can be observed on an acoustic test fixture (ATF) and characterized by the decrease of the earplug noise reduction (NR) when the earmuff is added. In this paper, a measurement methodology is proposed to (i) identify the main sound paths related to the DHP effect on an ATF and (ii) explain the latter by the relative contributions of the air-borne and structure-borne transmissions in the system. The focus is put on the NR values of the earplug alone and in the DHP. Measurement results suggest that the DHP effect is related to the energy transmitted from the earcup, through the earmuff cushion and finally into the earcanal via the sound radiation of the earplug and/or earcanal lateral walls. This flanking structure-borne path is found to dominate over the “direct” air-borne path through the hearing protectors at frequencies above 300 Hz.
PDF
