Plane Of Plate Research Articles

Wireless Power Transfer with Magnetic Flux Concentrator and Its Equivalent Circuit

This paper proposes a novel loosely coupled transformer (LCT) with a planar magnetic flux concentrator (MFC) for the wireless power transfer (WPT) in smart grid, which can improve the power of the receiving (Rx) coil. The MFC is a planar copper plate with a radial slit and a center hole, which is made of a printed circuit board (PCB). A simulation model and an experimental platform are built to investigate the performance of the LCT with and without an MFC. The results show that in the case of the transmitting (Tx) side with an MFC, the power of the receiving (Rx) coil increase by 33.82%. Besides, we propose the equivalent T-circuit for the LCT with an MFC.

Effect of porosity on rapid dynamic compaction of nickel nanopowder.

The shock-loading behavior of nanomaterials requires careful investigation because these complex systems are widely used in environments subjected to impulsive loads. Planar plate impact experiments are conducted to study shock compaction waves in 94% porous nickel powder containing spherical ∼55 nm particles in the pressure and strain rate ranges of 0.1-0.4 GPa and 106-107 s-1, respectively. The distinct two-step structure of these waves is captured by a laser velocimetry technique with high time resolution. This structure is caused by the formation of faster precursor waves traveling ahead of main compaction waves. The complexity of the shock Hugoniot curve of the tested nanomaterial is described using the obtained two-wave data and earlier results for higher pressures. The effect of initial porosity on the fronts of both waves and compressed states behind them is demonstrated using the current data and those that were collected previously for 50% porous samples of similar nanopowder.

Casimir‐Lifshitz Optical Resonators: A New Platform for Exploring Physics at the Nanoscale

AbstractThe Casimir‐Lifshitz force, FC − L, has become a subject of great interest to both theoretical and applied physics communities due to its fundamental properties and potential technological implications in emerging nano‐scale devices. Recent cutting‐edge experiments have demonstrated the potential of quantum trapping at the nano‐scale assisted by FC − L in metallic planar plates immersed in fluids through appropriate stratification of the inner dielectric media, opening up new avenues for exploring physics at the nano‐scale. This review article provides an overview of the latest results in Casimir‐Lifshitz based‐optical resonator schemes and their potential applications in fields such as microfluidic devices, bio‐nano and micro electromechanical systems (NEMS and MEMS), strong coupling, polaritonic chemistry, photo‐chemistry, sensing, and metrology. The use of these optical resonators provides a versatile platform for fundamental studies and technological applications at the nano‐scale, with the potential to revolutionize various fields and create new opportunities for research.

A Threshold‐Voltage and Drain–Source Current Model for Double‐Channel AlxGa1−xN/GaN/AlyGa1−yN/GaN High‐Electron‐Mobility Transistors

A physics‐based threshold voltage and drain–source current model based on double‐channel AlxGa1−xN/GaN/AlyGa1−yN/GaN high‐electron‐mobility transistors (HEMTs) is proposed in this article. Electrons limited in the potential well are derived from ionized donor‐like surface states of the AlxGa1−xN layer. Accumulated 2D electron gases (2DEGs) and positive charges left are equivalent to planar plate capacitors and further form electric fields, weakening the polarization fields in barrier layers. The physical properties of the dual‐channel HEMT are considered holistically rather than two separate and independent single heterojunctions. The effect of the charges and 2DEGs distributed in lower layers on the upper channel is contained in our model as well. Subsequently, a drain–source current model is proposed through coupling the critical electric field with the threshold voltage (VTH). The influence of channel length modulation, short channel effect, self‐heating effect, and kink effect is involved in this model. The accuracy of the proposed models is verified by comparison with technology computer‐aided design simulations and the experimental results. Proposed models can greatly describe the output characteristics, the transmission characteristics, and the relationship between VTH and device parameters of double‐channel AlGaN/GaN HEMTs.

Force-thermal analysis of large-area microchannel embedded cooling plate in improving thermal management of high-power density data centers

ABSTRACT A thermal management method for data centers from the server level is proposed in this paper. This paper explores the high energy consumption of the server itself, proposing a principle of microchannel shape design for a cooling plate based on the principal stress lines (PSLs). Under the condition of a uniform load, the influence of the cross-sectional shape of the microchannel on the contact thermal resistance was found to be insignificant. From the analysis of cooling plate plane, the uniformity of the stress distribution of the microchannel determined the uniformity of the contact thermal resistance, which determined the heat dissipation ability. Experiments were developed to test and verify the cooling performance of the cooling plate as well as the performance differences with the microchannels along and away from the PSLs under deformation. It was concluded that compared with the conventional serpentine microchannel, the cooling performance of the cooling plate proposed in this paper was 4.5 reduction in average temperature. Furthermore, when the ultra-thin cooling plate was subjected to a uniform load distribution, the microchannel along a single PSL had the best stress distribution, that is, the contact thermal resistance had the least variation.

Effect of the alumina micro-particle sizes on the thermal conductivity and dynamic mechanical property of epoxy resin.

Epoxy thermal conductive adhesives with high thermal conductivity and dynamic mechanical properties are important thermally conductive materials for fabricating highly integrated electronic devices. In this paper, micro-Al2O3 is used as a thermally conductive filler for the epoxy resin composite and investigated the effect of micron-sized alumina particle size on the thermal conductivity and dynamic mechanical property of epoxy resin by the transient planar hot plate method and DMA (Dynamic mechanical analysis). The experimental results show that with the same amount of alumina filling, the thermal conductivity and Tg (glass transition temperature) of epoxy/Al2O3 composite material decrease with the increase of alumina particle size. The maximum thermal conductivity of the composite material is 0.679 (W/mK), while the energy storage modulus of epoxy/Al2O3 composite material increases with the increase of alumina particle size, and the maximum energy storage modulus of the composite material is 160MPa. Compared with pure epoxy resin, the thermal conductivity and energy storage modulus have increased by 2.7 and 3.2 times, respectively. The epoxy/Al2O3 composite was applied to the COB (Chips On Board) type LED package, and the substrate temperature of the LED dropped to the lowest after 1.5 hours of operation using EP-A5 composite, and the temperature was stabilized at 38.2°C, indicating that the addition of 5-micron alumina composite has the best heat dissipation in the COB type LED package. These results are critical for the implementation of particulate-filled polymer composites in practical applications because relaxed material specifications and handling procedures can be incorporated in production environments to improve efficiency.

A Binocular Camera Calibration Method in Froth Flotation Based on Key Frame Sequences and Weighted Normalized Tilt Difference

3D froth information is a significant indicator of working condition recognition in froth flotation. To extract it accurately, the first and key step is camera calibration. Although there have been many camera calibration methods proposed in these years, they cannot handle well for binocular camera calibration in froth flotation. The main reason is that there is an open environment without support surface or special geometric shapes for camera calibration in froth flotation. Therefore, we propose a novel binocular camera calibration method based on key frame sequences and weighted normalized tilt difference. First, we extract a high-quality frame sequence by filtering out incomplete and out-of-focus images from the froth video. Then, we propose a method to measure the tilt degree of the planar plate and extract the key frame sequences of the planar plate based on the tilt difference. After that, we calculate the camera parameters by weighted normalized tilt difference under various poses. The proposed binocular camera calibration method uses the froth video to obtain accurate and robust camera parameters, and does not require auxiliary equipment. Experiments have demonstrated the effectiveness and flexibility of the proposed method in froth flotation.

Understanding the impact response of bird strikes on engine blades using a novel wedge-Hopkinson bar system

Bird strikes on engine blades, as a major concern for aviation safety, are complex impact events in which structural responses and bird deformations are coupled. To investigate the slicing process during a bird strike, a wedge-Hopkinson bar (WHB) system was developed to simulate a bird striking an engine blade. The system simplifies the measurement of impact responses by using strain gauges mounted on the bar to detect the signals. Systematic tests were conducted to determine the variation of impact responses using real birds with different masses and velocities. The peak impact force, transferred momentum, equivalent impact force, and time corresponding to the momentum centroid were obtained from the force-time histories to describe the impact process. The results identify the constancy of the normalized peak impact force and the normalized equivalent impact force against the impact velocity. However, the ratio of momentum transfer was found to decrease with increasing velocity. The experimental results for strikes on a wedge and strikes on an oblique planar plate revealed a reduction in the momentum transfer for the slicing state, leading to an impact of lower severity.

Air-breathing fuel cell with a columnar cathodic plate for the passive removal of water

Due to their high power density and reduced system requirements, passive proton-exchange membrane fuel cells (PEMFCs) are most appropriate for small and portable applications. These cells use static hydrogen and ambient air which poses important mass transport limitations of liquid water in the porous electrodes. In this work, a new cathodic plate is studied to optimize water transport and its removal from a passive PEMFC. The plate has an array of columns to favour the mobility and elimination of water drops over the cathode surface by the combining effects of gravity, capillarity, and evaporation. The performance of the new columnar plate is assessed by comparing with a perforated planar plate, and with a conventional PEMFC with flow-field plates. It is found that the columnar plate doubles the mass transport limiting current and peak power density of the planar plate. The analysis of the polarization curves and electrochemical impedance spectroscopy show that the columnar plate decreases water saturation in the cathodic gas diffusion layer (GDL) which improves the transport of gases. It is also found that the columnar plate decreases the dependence of cell performance on orientation which is advantageous for the operability in different applications. The peak power density of the passive air-breathing cell with columnar plate is 15% below that of a conventional cell with flow field plates, which allows to anticipate higher specific power density of the whole system in portable applications.

Influence of plate thickness on the results of residual stresses determination by through hole drilling in orthotropic composites of different fiber orientation

The main objective of this study is to characterize residual stress in composite orthotropic plates using hole drilling method. The values of hole diameter increment in the principal anisotropic directions, which were obtained from electronic speckle-pattern interferometry on the external surface of the specimen, serve as the initial experimental information. The theoretical foundation of the approach is based on S. G. Lekhnitsky's analytical solution, which describes a stress concentration along the edge of the central open hole in a rectangular orthotropic plate under tension in principal anisotropy directions. The transitional model, that is essential link for deriving residual stress components from initial experimental data, provides the unequivocally solution to the properly posed inverse problem. Firstly, the validation of the transitional model regarding prescription of residual stress values for specific plies within a specimen’s thickness is based on calibration experiments. These experiments yield data for unidirectional and cross-ply composite plates of three different thicknesses. The results demonstrate that the values of principal residual stress components for cross-ply composite material are independent of plate thickness. This means that the transition model, based on the measurements of deformation responses to through hole drilling on the external plate face, can be reliably implemented to characterize the maximal residual stress values present in the middle plane of the composite plate. An investigation into the effect of hole diamter values on the determination of residual stress is conducted for cross-ply and angle-cross-ply composites. It is shown that a hole of diameter of 3.2 mm provides the most reliable results.

Low-temperature conformal vacuum deposition of OLED devices using close-space sublimation

Close-space sublimation (CSS) has been demonstrated as an alternative vacuum deposition technique for fabricating organic light-emitting diodes (OLEDs). CSS utilizes a planar donor plate pre-coated with organic thin films as an area source to rapidly transfer the donor film to a device substrate at temperatures below 200 °C. CSS is also conformal and capable of depositing on odd-shaped substrates using flexible donor media. The evaporation behaviors of organic donor films under CSS were fully characterized using model OLED materials and CSS-deposited films exhibited comparable device performances in an OLED stack to films deposited by conventional point sources. The low temperature and conformal nature of CSS, along with its high material utilization and short process time, make it a promising method for fabricating flexible OLED displays.

Comparison of Dislocation Structures in Cu Deformed at Strain Rates from Quasi-Static to Shock Loading Using X-ray Line Profile Analysis

Polycrystalline copper samples were deformed in the range of strain rate between ~10−3 and 107 s−1 using a material testing machine, split Hopkinson pressure bar and electric gun. The quasi-static and Hopkinson bar samples were compressed at the strains of 0.1 and 0.4, and the electric gun samples were compressed at the shock pressures of 19, 25, 35 and 49 GPa. The dislocation structure in the recovered samples was determined using high-resolution X-ray line profile analysis. Compared to the quasi-static and Hopkinson bar tests, different characteristics of the evolution of dislocation density and arrangement were found in the planar plate impacts of the electric gun. The correlation between the flow stresses and the dislocation densities in the samples was discussed using the Taylor equation.

The DISCS method for perforation simulation of thin metallic plates by a rigid projectile

The DISCS method had been developed for penetration analysis of an axisymmetric projectile with a slender nose into a semi-infinite medium. Recently, the authors developed an approximate approach to assess perforation of concrete slabs of finite thickness, using the DISCS method. The present paper extends the approximate model to the perforation analysis of ductile metallic thin plates and determines the key parameters of the projectile residual velocity, the target perforation limit, and the ballistic limit. The present investigation focuses on thin metallic plates, the thickness of which is considerably smaller than that of the concrete slabs and smaller in comparison to the projectile nose length. The method is rather simple, easy to implement and provides a fast solution. An idealized target is characterized by a set of discs of small thickness responding in the plate plane, disregarding the local damage around the penetration ductile hole. The in-plane response of the discs during penetration and perforation of an idealized target are calculated. The Residual Velocity upon perforation of the Idealized Target (RVIT) is lower than the residual velocity of the real plate since it disregards the local damage, hence, the RVIT is the lower bound of the true residual velocity of the real perforated thin plate. Therefore, a positive RVIT for the thin plate with a given thickness indicates right away that the real target will be perforated. Using the RVIT parameter, the proposed DISCS method turns into a series of RVIT-perforation problems of plates with thicknesses that are smaller than the real thickness, to determine the decreasing RVIT with increasing thickness, until the full thickness is considered. The analysis is carried out using the modified (hybrid) DISCS method, that aims at analyzing penetration depth into a thick target. The analysis is based on the theoretical field equations and the constitutive equations of the plate material. The proposed method is based on a theoretical model and on engineering insight. Neither empirical constants nor any calibrations are required. Validation of the proposed method is carried out thorough comparisons with numerous test data on ductile aluminum and steel plates of different thicknesses that are struck by rigid projectiles at different impact velocities. All the comparisons demonstrate very good correspondence between the proposed method predictions and the test data.

Analysis of Drug Resistance, Virulence, and Phylogeny of Klebsiella pneumoniae in Patients with Different Infections

Background: Klebsiella pneumoniae is an important pathogen among nosocomial infections, which can cause urinary and respiratory system infections, surgical site infections, and sepsis. Recently, carbapenem-resistant K. pneumoniae showed an upward trend with the wide use of clinical carbapenem antibiotics. However, there are few studies on the relationship between drug resistance, virulence, and phylogeny of K. pneumoniae in patients with different infections. Objectives: We investigated the drug resistance, virulence, and phylogeny of K. pneumoniae in patients with different infections. Methods: Seventy infected patients were selected as subjects. The extended-spectrum β-lactamases (ESBLs) color screening plane and blood plate medium were used for culture. Identification and drug resistance analysis was carried out by VITEK-2 compact automatic bacterial analyzer. Multilocus sequence typing (MLST) and capsule genotyping analysis were also performed. The Xpert CarbaR cartridge detected the carbapenem resistance genes. Comprehensive Antibiotic Research Database (CARD) and Virulence Factor Database (VFDB) predicted the drug-resistant genes and virulence factor genes, respectively. The phylogenetic tree was constructed, and the correlation was analyzed. Results: A total of 43 K. pneumoniae strains were cultured. We found that all K. pneumoniae strains exhibited different multiple drug resistance. MLST analysis indicated that ST11 was the main ST (60.61%). Analysis of the carbapenem-resistance genes showed that all isolates harbored the blaKPC-2 gene and some others blaOXA. The prediction result of capsular blood genotyping and virulence factor genes indicated that K47, K64, and K25 were the main types of capsular blood, and the top three detection rates of virulence genes were fimH (97.67%), mrkD (94.19%), and entB (84.88%). All isolates were clustered into one branch based on the virulence factor genes in the phylogenetic tree, and the strains of the same ST type or capsular blood type showed a closer relationship. Correlation analysis manifested that the drug resistance of K. pneumoniae in infected patients was positively correlated with virulence and phylogeny (r = 0.682, P = 0.000). Conclusions: There were complicated differences in the multidrug resistance to K. pneumoniae, resulting in high independent gene-positive rates of strains and a strong correlation with phylogeny, which can provide a reference for the selection of clinical antimicrobial drugs.

Topological optimization of magnetic pulse welding coils for maximizing the effective weld area with a discretized differential evolution algorithm

A topologically constrained optimization methodology associated with a discretized differential evolution (DE) is employed for the structure design of a magnetic pulse welding (MPW) coil. To reveal the explicit expression for the effective welding area produced by the MPW process, the impact angle and collision velocity are innovatively considered for determination of the objective function. As several disconnected regions are generated by the Rand-to-Best/2/exp mutation strategy and subsequent superposition-style crossover operation, the algorithm is combined with geometrical correction to form a simply connected conductor. The proposed algorithm is effective and robust as it have been verified based on the evolutionary history and numerical trials with coupled electromagnetic–mechanical simulations. According to physical validation results, a wider effective welding area is produced between aluminum alloy and steel planar plates by the optimized coil, which results in better performance in a tensile test. Under a 23 kJ discharge current, the maximum loading is significantly enhanced by 46.21% compared with the original coil.

Maximisation of Bending and Membrane Frequencies of Vibration of Variable Stiffness Composite Laminated Plates by a Genetic Algorithm

PurposeIn comparison to traditional, constant stiffness laminates, variable stiffness composite laminates (VSCL) with curvilinear fibres represent an extra analysis effort. It is the purpose of this work to present and test a relatively simple optimisation procedure, in order to find the maximum fundamental frequency of vibration in bending and in in-plane vibrations. It is also intended to explain why certain fibre paths lead to higher frequencies.MethodsThe optimisation is performed using a genetic algorithm (GA), which is described in detail. The bending and the in-plane plate models are based on the p-version Finite Element Method. Each model requires a small number of degrees of freedom, an important feature because applying the GA involves the solution of a large number of eigenvalue problems. In order to support the physical interpretation of the optimal designs, mode shapes and stress fields corresponding to some optimal solutions are illustrated.ResultsSingle- and multi-layer plates with different boundary conditions and fibre path types are studied. Fibre paths that lead to maximum fundamental frequencies are found and justified. The consequences that maximising the first frequency has on the higher-order modes of vibration are studied.ConclusionThe proposed optimisation and modelling methods are effective. Curvilinear fibres with the characteristics considered led to the maximum first natural frequency of vibration in a few cases, but not all. Particularly in in-plane vibrations, curvilinear fibres can provide major gains in comparison to straight fibres. The increase in the vibration frequency is accompanied by, overall, larger stresses.

Semi-analytical solution for interfacial debonding of high-speed railway ballastless track under thermal loading using a quasi-dynamic method

Interfacial debonding of multi-layered ballastless track systems has proved to be one of the most common diseases in the high-speed railway during long-term operations. This paper focuses on the theoretical modeling of track temperature field and consequent bond-slip behavior between track layers under thermal loading. By establishing heat conduction differential equations, whose boundary conditions are combined with complicated geographical and meteorological factors, the temperature field of a multi-layered track structure is obtained via the integral transform technique. The reliability of the heat conduction model is well-validated by an on-site experiment in a high-speed railway line. Then, we originally extend an explicit integration algorithm for dynamics analysis to solve nonlinear statics problems with small deformation by proposing a quasi-dynamic method (QDM). Equilibrium equations of a track slab subjected to quasi-dynamic equivalent thermal loads and mixed-mode interfacial cohesive forces are constructed based on the Mindlin plate in-plane and flexural vibration equations. The application of the QDM to solve interface responses is verified by comparing results obtained from finite element (FE) software. Finally, numerical discussions are conducted to reveal the nonlinear distribution characteristics of temperature field, evolution process of the interface damage and failure modes under time-varying thermal loads, which provide a better understanding of the interfacial debonding phenomenon encountered in ballastless track systems.

Variable stiffness plate tensegrity structures inspired with topology optimization

The present study focuses on the research on modular tensegrity-based plate lattices, which are reinforced with an internal skeleton consisting of enhanced tensegrity cells. The enhanced cells that create the skeleton should have different mechanical properties than other cells of the lattice. The novel idea described in this study consists in using the results obtained from the topology optimization of various plate structures and to simulate the topologically optimal material layout in the corresponding lattice plates by using the reinforced skeleton. Three possible ways of adjusting the properties of tensegrity cells within the lattices are described: adjustment of geometric parameters, i.e. cable-to-strut stiffness ratio, adjustment of the self-equilibrated system of normal forces, and the hybrid solution. The effectiveness of the proposed techniques is demonstrated for two in-plane plate deformation tasks. Although this study focuses on large-scale plate lattices, a similar approach can also be applied to smaller scales.

A self-centering hybrid braced precast wall with replaceable U-shaped flexural plates: Experimental and theoretical analysis

A self-centering hybrid-braced precast wall with replaceable U-shaped flexural plates (UFPs), which is composed of a hybrid braced wall, post-tensioned (PT) strands, and steel wall toes, is proposed. The UFPs bolted inside the steel wall toes, which yield at the same thickness outside the plane of the steel plate when wall rocking, providing plastic bending energy dissipation. The steel wall toe made of H-shaped steel provided increased compressive strength and space for the installation of the UFPs. Four wall specimens with varying initial PT forces, UFPs of different thicknesses, and different dampers were investigated using low-cyclic loading tests. After replacing the UFPs, one wall was retested to assess its performance. The precast walls sustained significantly low damage and showed large self-centering capabilities. The maximum drift was up to 4.5%, which far exceeded the specified requirements, and the lateral load still maintained an increasing trend. When the initial PT force was increased, the bearing capacity, initial stiffness, and self-centering capacity of the precast wall increased. When the thicknesses of the UFPs were increased, the energy-dissipation capacity and self-centering capacity of the wall increased and decreased, respectively. The self-centering and bearing capacities of the repaired wall met the seismic requirements but were slightly lower than those of the original wall. The wall with UFPs performed better bearing capacity and stiffness than the wall with variable friction dampers (VFDs) before 1.5% drift. Additionally, the opening load of the wall, the load at the yield of UFPs, and the load at different compression sections were calculated and compared against the test results. The analysis method was able to predict the behavior of the walls reasonably well.

Influence of Dielectric Plate Parameters on the Reflection Coefficient of a Planar Aperture Antenna

In this article, an aperture antenna excited by a waveguide with a circular cross-section and covered with a dielectric plate was analyzed via simulation calculation and verified via measurements. The influence of the geometrical and electromagnetic parameters of the dielectric plate on the reflection coefficient S11 of the antenna opening was systematically analyzed. The geometrical parameters taken in this analysis are the thickness d and the width/length h1/h2 of the dielectric plate. The electromagnetic parameters used in this analysis are the real and the imaginary part of permittivity (εr, tan δ) and the electrical conductivity of the dielectric plate (σ). The simulation calculation and analysis included other structural and electromagnetic parameters of the dielectric plate (density of the radome material, relative permeability, and magnetic loss tangent (ρ, µr, and tan δµ, respectively)), but the results show that in the range of real values of these parameters for the materials used for the dielectric plate, they had no significant influence on the reflection coefficient. The results show that impedance-matched antennas with very low values of the reflection coefficients S11 at the resonant frequency can be realized by changing the geometrical and electromagnetic parameters of the dielectric plate material. The results are presented for a circular aperture antenna on a planar grounded plane with a dielectric plate on the opening, and the achieved lowest values of the S11 parameter were −45.17 dB (simulated) and −43.93 dB (measured) at the frequencies of 1.7820 GHz and 1.7550 GHz, respectively. The estimated values of the dielectric plate parameters in this case are thickness d = 11.08 mm (0.67 λ); width × length of grounded plane and dielectric plate h1 × h2 = 423 × 450 mm2 (2.51 × 2.67 λ); relative permittivity 2.5, tan δ = 0.09, μr = 1, tan δμ = 0.00, ρ = 1200 kg·m−3; and electrical conductivity σ = 0 S/m. The simulation calculation results were verified by measuring the reflection coefficient S11 on the created laboratory model of the aperture antenna with the dielectric plate and showed a very good match.