Plane Of Plate Research Articles

Mathematical model of turbulent heat transfer based on the dynamics of two fluids

A new approach to modeling turbulent heat transfer based on the thermodynamics of two fluids is presented in the paper. This study is a development of a two-fluid turbulence model. It was shown that the temperature fluctuation in a turbulent flow is due to the temperature difference of these fluids. A mathematical model of turbulent heat transfer was built on the basis of the two-fluid approach. The obtained mathematical model of turbulence was used to study turbulent heat propagation when flowing past a plane plate, in round and plane jets, and between two rotating cylinders. To verify the model, numerical results were compared with known experimental data. The results obtained showed that the two-fluid model of turbulent transfer describes the thermodynamic properties of the turbulent flow with great accuracy.

New Insights into the Failure Front Phenomenon and the Equation of State of Soda-Lime Glass Under Planar Plate Impact

A systematic study has been performed to gather more detailed experimental information on the equation of state and the Hugoniot elastic limit (HEL) of soda-lime glass as well as the failure front phenomenon. The key innovations of this study comprise experimental as well as analytical aspects. On the one hand, an extensive planar plate impact (PPI) test series has been carried out over a wide range of shock loading stress levels instrumented with two high-speed cameras and laser interferometers (PDV and VISAR). On the other hand, a systematic analysis concept has been developed and evaluated, including a combination of Lagrange diagrams with velocity profile data and a derivation of the equation of state together with an error estimation. Impact velocities ranged from 500 to 3000 m/s resulting in loadings of the soda-lime glass targets between 3.5 and 20.8 GPa. For stress levels between 3.5 and 6.7 GPa two high-speed cameras with 5 Mfps, positioned at the side and rear of the specimens, enabled the observation of shock waves and two different kinds of failure fronts. Therefore, visual information could be gathered not only in the purely elastic regime, but also in the transition region above 4 GPa and at stress levels beyond the HEL. The HEL of the soda-lime glass is determined to left(5.0 pm 0.2right) mathrm{GPa}. For the onset of an internal failure front a minimum longitudinal stress between 3.8 and 3.9 GPa is identified. The evaluated failure front velocities range from 800 to 2100 m/s. From the observed release response a minimum spall strength of 6.7 GPa and release wave velocities between 5740 and 9500 m/s are deduced.

Towards model-based approaches for musical instruments making: validation of the model of a Spanish guitar soundboard and characterization features proposal

Nowadays, the virtual prototyping method is widely used for industrial applications and can lead to a powerful tool for musical instruments making and conservation. Nevertheless, physics-based models of musical instruments are barely developed for this purpose and the confrontation between model predictions and experiments have been the focus of very few researches. The objective of this paper is to highlight the predictive capability of physics-based models in vibratory domain, even in presence of variable by nature material and climatic conditions. To this end, a finite element model of the soundboard of a Spanish guitar is developed for model validation purposes. The simulated modal bases are compared with experimental ones from a previous study. Screening and stochastic analyses are performed to rank which are, among material and climatic parameters, the most influential ones on the dynamics of guitar soundboard. Moreover, uncertainties are taken into account to evaluate the dispersion of the response for a given design, and simulations are validated facing experimental data. It is shown that specific elastic parameters of the wood (in longitudinal and radial directions and longitudinal-radial plane) of the top plate are mainly influential with regard to the dynamics of the soundboard, and the relative humidity changes have a non negligible impact. Moreover, test-model correlations have shown that a nominal model with average material parameters is able to predict the vibratory behaviour of a real braced soundboard with an average error on the first eight eigenfrequencies lower than 4%. In addition, when uncertainties are taken into account, the model is able to predict every experimental data. Finally, dynamic features like CFDAC and Fuzzy-FRF are proposed in an innovative way in this application domain.

Comparison of Planar and Tubular Flow Field Plates for Proton Exchange Membrane Fuel Cells (PEMFCs) through Simulation

Proton exchange membrane fuel cells are excellent clean energy alternatives to current non-renewable energy sources. Bipolar plates are a key component of these fuel cells and directly responsible for their performance. Traditional bipolar plates are created in a planar form, but recent research has revealed a novel tubular design that performs similarly to conventional plates. This study compares traditional planar designs with tubular ones. The finite element ANSYS software was used to determine and visualize velocity and pressure distributions of fluid flow through the bipolar plate channels.

Space and Time Characteristics of the Velocity and Pressure Fields of the Fluid Flow Inside a Hemispherical Dimple Generator of Vortices

Results of experimental investigations of the space and time characteristics of the velocity and pressure fields of the fluid flow inside a hemispherical dimple on a plane plate are presented. Features of the formation and development of vortex strictures in such a dimple and the interaction of these structures with the dimple surface over which the fluid flows and with the boundary layer of the fluid flow were investigated. Integral, spectral, and correlation characteristics of the oscillations of the flow velocity and the dynamic and near-wall pressures in the dimple have been obtained. The velocity and direction of transfer of large-scale vortex structures and the frequency of their rotation inside the dimple, the frequency of throw of these structures out of the dimple, the frequencies of the velocity and pressure oscillations of the vortex flow in the dimple, the frequency of the self-vibrations of the vortex structures in the shear layer of this flow, and the subharmonics and higher-order harmonics of the indicated frequencies were determined.

Search for hidden-photon cold dark matter using a K-band cryogenic receiver

We search for hidden-photon cold dark matter (HP-CDM) using a spectroscopic system in a K-band frequency range. Our system comprises a planar metal plate and cryogenic receiver. This is the first time a cryogenic receiver has been used in the search for HP-CDM . Such use helps reduce thermal noise. We recorded data for 9.3 hours using an effective aperture area of 14.8 cm2. No signal was found in the data. We set upper limits for the parameter of mixing between the photon and HP-CDM in the mass range from 115.79 to 115.85 μeV, χ < 1.8–#4.3e−10, at a 95% confidence level. This is the most stringent upper limit obtained to date in the considered mass range.

УСТАНОВКА ДЛЯ ДОСЛІДЖЕННЯ ТЕПЛОПРОВІДНОСТІ ЕНЕРГОЕФЕКТИВНИХ ТЕПЛОІЗОЛЯЦІЙНИХ МАТЕРІАЛІВ РОСЛИННОГО ПОХОДЖЕННЯ

One of the key point criteria of any thermal insulation material that determine its energy efficiency is thermal conductivity. Determination of thermal conductivity of materials of plant origin, as well as any other, can be reliably determined only experimentally. The proposed original design of an inexpensive installation for studying the thermal conductivity of heat-insulating materials of plant origin contains a heat-insulated empty body for placing the test sample and a heat source. The heat flow is created by a heating element, which consists of an upper and lower metal plate of a given thickness with a known coefficient of thermal conductivity. The volume created between the plates is filled with a layer of quartz sand to create additional homogeneous heat flow. This design of the heating element provides a homogeneous distribution of heat flux over the cross-sectional area of the test sample of the insulating material. To register the change in the magnitude of the heat flux, thermocouples are used, which are located on the inner surface of the upper plate of the heat source and on the cold side of the investigated sample of heat-insulating material. Data on temperature changes are registered by the automatic registration block. A tubular electric heater of appropriate configuration is symmetrically attached to the lower plate along the cross-sectional area. The tubular electric heater is connected to the voltage control unit. Between the lower plane of the lower plate and the housing of the installation there is an air layer to minimize heat loss from the heating element. The coefficient of thermal conductivity, which characterizes the efficiency of the insulating material, is calculated by the known Fourier formula for the steady-state temperature regime from the input information about the temperature difference in the characteristic cross sections of the sample.

Gain enhancement of co-planar waveguide fed ultra-wide bandwidth monopole antenna with enlarged ground plane and metal reflectors

This study investigates the capability of an omnidirectional monopole antenna in achieving a high gain pattern that can be used in the UWB applications covering the frequency range of 3.1–10.6 GHz. The gain of a co-planar fed reference antenna with a partial ground is enhanced by using two main techniques; incorporating the antenna with an enlarged ground plane and metal reflector plates in different configurations. The gain level of the reference antenna in the yz-plane (1.9–4.6 dBi) is enhanced up to a gain level of 9.25–14.8 dBi with the help of the two gain enhancement techniques. Furthermore, a minimum gain of 12 dBi with a maximum deviation of 3 dBi is observed over the 4.2–9.8 GHz frequency range. As a proof of concept, two configurations of the designed antennas are fabricated and tested.

Widefield, Spatiotemporal Mapping of Spontaneous Activity of Mouse Cultured Neuronal Networks Using Quantum Diamond Sensors

Quantum diamond sensors containing Nitrogen Vacancy (NV) centers were integrated into the culture of spontaneously electrically active cultures of live mouse primary cortical neurons. Two diamond formats were used enabling extracellular studies of cells cultured directly on a planar diamond plate and intracellular studies via endocytosis mediated integration of nanoscale diamond particles within cells. Over a 14 day culture period functional neuronal networks formed as confirmed by endogenous calcium transients detected via fluorescent imaging of a calcium probe (Fluo-5 AM). Spatially correlated images of photoluminescence from NV centers were also recorded demonstrating successful acquisition of optically detected magnetic resonance from regions of endogenously firing neuronal cultures. Further, a fast and simple measurement protocol based on acquisition of NV photoluminescence without and with the application of near resonant microwaves is presented. This protocol was applied to live signaling cells and dead cells. The relative photoluminescence from NVs with and without microwaves varied for the case of live as compared to dead cells warranting future investigation. Overall this work presents a protocol for integration of NV diamond sensors in a spontaneously active network of neuronal cells of relevance to the field of neuroscience. Photoluminescence from NV centers was detected with high spatiotemporal resolution using measurement protocols potentially capable of single shot detection of neuronal activity. It is anticipated that the methodologies introduced in this work will underpin the establishment of NV diamond sensors as a radically new measurement platform capable of rapid, non-destructive functional studies of cells.

Influence of Jet Position on Local Heat Transfer Distribution under an Array of Impinging Nozzles with Non-Planar Contour of the Cooled Surface

Many experimental and numerical investigations of arrays of impingement cooling jets have been performed. A lot of them have addressed the problem of cooling with jets directed perpendicularly or inclined to the planar plate. However, in many technical applications contour of the cooled surface is more complex. One of the examples is a casing of the low-pressure turbine of the jet engine. It’s shape is determined by the turbine flow path and position of the blades and vanes located circumferentially inside the casing. Position of the cooling jets is limited by surrounding components, thermal expansion, and vibrations occurring during the engine operation. The investigation focused on the area at which the air has to be blown to achieve most effective cooling system for the complex geometry of the cooled surface is still open. The main goal of the numerical investigation performed in this study was to examine various axial positions of the jets directed perpendicularly to the non-planar shape of the surface to achieve the most effective Nusselt number distribution. Twenty-one analyses with different locations of array of cooling nozzles and various temperature ratios were taken into consideration. The numerical calculations of the thermal and flow parameters were performed using computational fluid dynamics code Ansys CFX.

Focusing of Long-Wavelength X-Rays by Means of Spherical and Planar Microchannel Plates

The possibility of focusing (concentration) of long-wavelength X-rays by thick spherically bent and planar microchannel plates has been studied experimentally and theoretically. The electrodynamic simulation of emission from a finite antenna array consisting of noninteracting emitters, which are hollow microchannels, has been performed. It has been shown theoretically that the parallel beam of synchrotron radiation can be efficiently focused not only by a spherical microchannel plate but also by a pair of plane-parallel plates.

Semi-Analytical Solutions for the Uniformly Compressed Simply Supported Plate with Large Deflections

The thin plane plates are largely used in practice as single elements or as components of the thin-walled structures, and their behavior under compression is characterized by large post-buckling load-carrying capacity. Various semi-analytical solutions of the uniformly compressed simply supported plate with large deflections were formulated almost a century ago, mainly solving the fundamental equations governing the deformation of thin plates, or using classic energy methods. Due to several shortcomings, none of these solutions were introduced in the design codes of thin-walled members. This paper presents new semi-analytical solutions based on classic energy methods. The main innovation is brought by the considered displacement field which is far more accurate than the ones used by the previous formulations. The initial geometric imperfections are considered, and the proposed solutions are validated against numerical solutions and experimental data. The validation is also supported by a publicly available software application.

A study on the type-b hot spot stress

Stress distributions in the vicinity of type-b hot spot in the in-plane gusset welded joints and in the free edge of the stiffened cruciform welded joints were evaluated according to the solid model, the fine mesh shell model, and the coarse mesh shell model. The hot spot stress (HSS) of each FE model was evaluated by extrapolating the stresses at the read out point (ROP) to the hot spot position according to the recommendations of IIW and were compared. Regarding the in-plane gusset welded joints, it is confirmed that the HSS by the solid model and the shell model are corresponding in the case of in-plane notch in which the thicknesses of the main plate and the gusset plate are same. It is observed that the shell model estimates lower HSS than that by the solid model when the main plate is thicker than the gusset plate. The reason of this difference is considered that the shell model does not evaluate the stress distribution in the thickness direction of the main plate in front of the in-plane gusset plate but evaluate the averaging stress. A simple correction factor to the HSS evaluated by the shell model based on the ratio of both plate thicknesses was examined. Regarding the free edge of the loaded attached plate in the stiffened cruciform welded joints, it is confirmed that the hot spot is on the corner edge of the attached plate. It is observed that the shell model estimates lower HSS than that by the solid model.

Anatomical relationship of pterygoid process pneumatization and vidian canal

IntroductionThe vidian canal acts as landmark for the identification of the petrous carotid artery, especially during extended endoscopic endonasal approaches in cranial base surgeries. In order to localize the canal and to understand the relationship of pneumatization of pterygoid process to the type of vidian canal, this study was designed. ObjectivesThe objective was to describe the anatomical relationship of pneumatization of the pterygoid process with types of vidian canal. The length of vidian canal, relationship to medial plate of pterygoid process and relationship to the petrous part of internal carotid artery were evaluated. MethodsHead computer tomography scans of 52 individuals for suspected paranasal pathology were studied. The degree of sphenoid sinus pneumatization, pterygoid process pneumatization and types of vidian canal (type 1, 2 and 3) were noted. The length of vidian canal, distance from the plane of medial pterygoid plate and relation of vidian canal to the junction of petrous and Gasserian (ascending) part of internal carotid artery was noted. Results46 (92%) sphenoid sinuses were of the sellar variety. Out of 104 sides that were studied, 57 sides demonstrated a pneumatised pterygoid process and 47 were not pneumatised. In 49 sides (47.1%) the vidian canal was on the same plane as that of the medial pterygoid plate in the coronal section. The vidian canal partially protruded into the sphenoid sinus (type 2) was the most common type (50.9%), found both on right and left sides. There is a statistically significant association between the pterygoid process pneumatization and occurrence of type 2 and type 3 vidian canal configuration. The average length of the vidian canal was 16.16 ± 1.8 mm. In 96 sides, the anterior end of vidian canal was inferolateral to petrous part of internal carotid artery in the coronal plane. ConclusionPneumatization of the pterygoid process indicates either type 2 or type 3 vidian canal configuration.

Impact of Platelet-rich Plasma in the Healing of Through-and-through Periapical Lesions Using 2-dimensional and 3-dimensional Evaluation: A Randomized Controlled Trial

IntroductionThe purpose of this randomized controlled trial was to evaluate the role of platelet-rich plasma (PRP) in the healing of through-and-through periapical lesions using both 2-dimensional periapical radiographs and 3-dimensional (3D) cone-beam computed tomographic imaging. MethodsThirty-four patients after confirmation of a through-and-through periapical lesion were enrolled and randomly assigned to either the control or PRP group. Periapical surgery was performed, and grafting of the bone defect with PRP was done in the PRP group before suturing. Follow-up was scheduled at 12 months for clinical and radiographic analysis based on Molven's criteria; modified Penn 3D criteria; and resected plane, apical area, and cortical plate indexes. The absolute area and volume of the lesions were measured preoperatively and at follow-up using CorelDRAW X7 (64-bit) (Corel Corporation, Ottawa, Canada) and ITK Snap software (free software under the GNU General Public License developed by the National Institutes of Health, the US National Institute of Biomedical Imaging and BioEngineering, the US National Library of Medicine, the Universities of Pennsylvania and North Carolina, and an independent developer group), respectively. ResultsThirty-two patients were available at follow-up. A success rate of 93.7% was observed for both the control and PRP groups on 2-dimensional evaluation, whereas the PRP group exhibited a significantly higher success rate (87.5%) than the control (50%) on 3D assessment. A significantly higher percentage reduction in the lesion volume was documented in the PRP group (92.30 ± 4.72) than the control group (83.04 ± 12.82). Resected plane, apical area, and cortical plate indexes revealed a significantly higher scoring at the resected plane and cortical plate parameter in the PRP group. Overall analysis documented the faster re-establishment of the palatal cortical plate than the buccal cortical plate in through-and-through lesions. ConclusionsThese results suggest that PRP improves the healing outcome in through-and-through lesions. CBCT imaging provides better healing assessment after periapical surgery over periapical radiographs in such lesions.

Numerical simulation of hydrogen active magnetic regenerative liquefier

Abstract This paper is focusing on a numerical investigation of hydrogen Active Magnetic Regenerative Liquefier (AMRL). For this purpose, two-dimensional transient numerical modeling with finite volume method has been developed (i.e. CFD method) to simulate the parallel plane plate (PPP) AMRL regenerators type in order to predict and investigate its thermal performances. The resulting mathematical model has been implanted in ANSYS-Fluent software to overcome the complexity of the Active Magnetic Regenerative (AMR) cycle. To run the simulations, a six cascade-stages hydrogen AMRL cycle has been proposed. From the first to the last stage, the regenerators are made of the following magnetic materials: Gd, Tb, Dy, Ho, Er and Tm respectively. The validity of the proposed model has been performed through Cristal2 AMR demonstrator built to operate at room temperature. Good agreements have been found between experimental and numerical results. Then, simulations of the proposed multistage hydrogen AMRL have been carried out for applied magnetic induction up to 7 T. It has been shown that a mass flow rate of 100 mg s−1 of hydrogen initially at 300 K and 1 atm can be cooled down to 57 K. Thus, the capability of the proposed CFD method for predicting consistent results has been demonstrated.

Dynamic stability and vibrations of thin-walled structures considering heredity properties of the material

Dynamic stability and vibrations of thin-walled structures, taking into account the heredity properties of the material are considered in the paper. Mathematical models were constructed in a two-dimensional statement, using the Karman theory of plane plate strains and A.A. Ilyushin aerodynamic theory. When realizing the physico-mechanical properties of the material of the object, the systems of integro-differential equations (IDE) in partial derivatives with the corresponding initial and boundary conditions are taken as mathematical models of the problems under consideration. The obtained nonlinear partial IDEs using the Bubnov-Galerkin method under considered boundary conditions are reduced to solving systems of nonlinear ordinary IDEs with constant or variable coefficients with respect to the time function. The integration of equations obtained using the polynomial approximation of the deflections was carried out by a numerical method based on the use of quadrature formulas. Based on this method, an algorithm for the numerical solution of the problem was developed suitable for all viscoelastic and elastic elements of thin-walled structures of plate type.

Study on visual machine-learning on the omnidirectional transporting robot

We present a computer vision solution integrated to an omnidirectional transporting robot to perform the position tracking of multiple trays moving on its planar acrylic plate surface. The trays were designed to carry lightweight materials on top of their surface so that the mechanism could be implemented as an automated transporting system for applications that require the displacement of products and/or materials in any given space. One hurdle faced by the visual system for suitable detection was the partial occlusion of the image of a tray when placing arbitrary objects on its surface. Our strategy to overcome this challenge consisted on the implementation of machine learning algorithms, such as Support Vector Machines (SVM), using datasets of images containing trays with different occlusion patterns for fast object detection through rigorous training. The results of experimental tests validate the implementation of our proposal as a reliable approach for the object tracking of multiple trays on the robotic device, even under partial occlusion. We also studied the accuracy of the position measurements performed by our visual system with respect to the position measurements taken by the OPTITRACK motion capture system and evaluated the processing time per frame required by the software implementation.

Two-Dimensional Plate Theory for the Analysis of Coupling Vibrations in Shear Mode FBARs

The shear mode film bulk acoustic wave resonators (FBARs) have been developed rapidly in recent years due to the increased interest in biosensors. In this paper, the mode coupling effects which are unavoidable in real devices are theoretically analyzed and discussed. Mindlin's approximation method of expanding the displacement fields with power series along the plate thickness direction is employed and a system of two-dimensional plate equations is obtained. The accuracy of the plate theory is validated through the comparison of dispersion curves with the results calculated by three-dimensional exact theory. Free coupling vibrations of the cross-sectional plane of finite-sized shear mode FBAR plates are further studied with the derived two-dimensional theory. Results in this paper show that the presented plate theory is accurate and efficient for the structural analyses of shear mode FBARs. Besides, the selection of aspect ratios can be used to avoid strong mode couplings, which is helpful for device designs.

Self and cross-mode interactions in a weakly nonlinear two-dimensional structural-acoustic waveguide.

In this study, that is entirely semi-analytical, weakly nonlinear wave propagation in an infinite two-dimensional structural-acoustic waveguide is studied. The lower boundary of the waveguide is a rigid wall, while the top boundary is a flexible plate. Both in-plane and transverse displacements are included in the flexible plate model. The acoustic fluid and the plate are modeled using standard nonlinear equations. The waveguide is driven by an oscillating piston at the origin. The regular perturbation method is used to separate the equations at linear and nonlinear order. The self- and cross-mode interactions of the non-orthogonal propagating modes are solved for. It is found that in the self-mode interactions, resonances occur both in pressure and in the in-plane plate displacement at their own different frequencies. Whereas in the cross-mode interactions, there is no in-plane plate resonance and mostly beats (in space) occur except at some frequencies where resonance in pressure is seen. Also, boundary flexibility reduces the number of resonances drastically in comparison to the rigid waveguide. The relevant conditions and closed form solutions are derived for the resonance cases. It is also observed among the nonresonant solutions (or beats) that below the coincidence frequency, the bending mode dominates, and above the coincidence frequency, the acoustic mode dominates.