Top Plane Research Articles

On the crack inverse problem for pressure waves in half-space

After formulating the pressure wave equation in half-space minus a crack with a zero Neumann condition on the top plane, we introduce a related inverse problem. That inverse problem consists of identifying the crack and the unknown forcing term on that crack from overdetermined boundary data on a relatively open set of the top plane. This inverse problem is not uniquely solvable unless some additional assumption is made. However, we show that we can differentiate two cracks Γ1 and Γ2 under the assumption that R3∖Γ1∪Γ2‾ is connected. If that is not the case we provide counterexamples that demonstrate non-uniqueness, even if Γ1 and Γ2 are smooth and “almost” flat. Finally, we show in the case where R3∖Γ1∪Γ2‾ is not necessarily connected that after excluding a discrete set of frequencies, Γ1 and Γ2 can again be differentiated from overdetermined boundary data.

Microfluidic SIW-Based Tunable Self-Diplexing Antenna for Sub-6 GHz Band Applications

This work introduces a novel frequency tunable self-diplexing antenna (SDA) design based on substrate integrated waveguide (SIW) technology. A modified A-shaped slot is employed on the cavity’s top plane, which is excited by two independent <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\Omega $ </tex-math></inline-formula> microstrip feed lines to operate at each resonant frequency. The frequency flexibility of the proposed antenna allows for fine-tuning at each resonance frequency. The frequency flexibility has been achieved by employing the substrate’s air- and liquid-filled pockets. The proposed antenna can be configured to operate in the 3.5-3.8 GHz and 5.53-6.2 GHz bands, as demonstrated by the simulation results. With distilled water-filled pockets, the proposed antenna offers peak gains of 5.04 dBi and 5.26 dBi. The proposed SDA exhibits competitive features such as a highly compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.22\lambda _{g} ^{2}$ </tex-math></inline-formula> and high isolation (>27dB), which makes it suitable for handheld communication devices. The simulated and measured circuit responses are in good agreement.

Ideal micro-lenticular lens based on phase modulation of optically isotropic liquid crystal-polymer composite with three terminals

Optical phase modulation in a transparent polymer film composed of nano-sized liquid crystal (LC) droplets embedded within a polymer matrix exhibits a micro-lenticular lensing effect under controlled in-plane field switching (IPS) with interdigitated electrodes. Despite of the lensing effect, the lens profile does not match ideal one and its effective phase modulation is relatively small owing to the weak field strength over the electrodes, which causes an invariant refractive index in these regions. To achieve ideal lens profile and high phase modulation, a vertical electric field is applied between top plane and bottom interdigitated electrodes, while maintaining the in-plane fields between the bottom interdigitated electrodes. The combined effect, referred to as the vertical and in-plane switching (VIS) mode, can achieve larger phase modulation (Δδ) than the IPS mode. Consequently, the proposed micro-lenticular lens has a shorter focal length and a significantly better lens profile, similar to the ideal one. Furthermore, the diffraction efficiency (Df) is effectively improved by ∼ 6.7%, 4%, and 2% for the zeroth (0th), ±1st, and ± 2nd orders, respectively, compared to those in the IPS mode. The improved phase profile with the proposed micro-lenticular device can be used in a switchable lens from 2-dimensions (2D) to 3-dimension (3D) and tunable diffractors.

Highly Compact 4 × 4 Flower-Shaped MIMO Antenna for Wideband Communications

This paper introduces an MIMO antenna with a highly compact size of 30 mm width and 30 mm length. Four symmetrical MIMO antenna radiators are utilized with decoupling stubs in the top and bottom planes of the substrate to improve the isolation level. The simulated and measured outcomes are validated to investigate the impact of the suggested MIMO antenna for wideband applications. The suggested MIMO antenna has an impedance matching less than −10 dB from 5.8 GHz up to 11 GHz, and the isolation between the four radiators exceeds 20 dB over this band. Moreover, the antenna provides an envelope correlation coefficient not exceeding 0.004, a diversity gain above 9.97 dB, and a mean effective gain of ≤−3 dB over the achieved frequency range. The suggested MIMO antenna exhibits a nearly omnidirectional radiation pattern in one plane and a bi-directional radiation pattern in the other plane with an acceptable average value of the realized gain (4 dBi) over the achieved frequency band. A comparison with the state-of-the-art is tabulated to show the distinct performance of the suggested MIMO antenna for wideband applications.

UWB‐BPF based on broadside coupled technology with triple‐notched passband

AbstractA miniaturized ultra‐wideband (UWB) bandpass filter (BPF) based on broadside coupled technology with multiple passband notches is reported. The basic geometry of BPF has microstrip lines on the top plane coupled to the modified short‐circuited coplanar waveguide in the bottom plane. This broadside alignment leads to the development of a UWB response with good frequency characteristics due to the presence of two transmission zeros at lower/upper passband edges. Later, multiple circular resonators and one complimentary folded split ring resonator are embedded into the basic architecture to develop triple passband notches at our frequencies of interest. Eventually, a prototype is fabricated and tested to validate the simulated data. The proposed BPF occupies a minimal physical area of 14 × 11.4 mm2.

Design of double-notch UWB filter with upper stopband characteristics based on ACPW-DGS.

In this manuscript, a compact (size only 9.8mm*9.8mm) Ultra Wide Band (UWB) bandpass filter with a new structure is proposed, which can be used in the UWB wireless communication band authorized by the FCC. The top plane is composed of a pair of back-to-back microstrip lines, and the ground plane structure is based on an asymmetric coplanar waveguide-defect ground structure (ACPW-DGS). UWB is formed by the vertical electromagnetic coupling of the top plane and the ground plane. On this basis, split ring resonator (SRR) and C type resonator (CTR) are utilized to place double notch bands. A novel third order nested C-type resonator (TONCTR) is obtained by performing CTR, which can further optimize the upper stopband while ensuring double notch bands. The filter can be used for filtering within the UWB system, and it can also avoid the amateur radio band (9.2 -10.3GHz) and the X-band satellite link band (9.6-12.3GHz) on UWB communication systems. Finally, the measured results from the fabricated prototype are basically consistent with the simulation results.

Ku-Band SIW Filter with High Fractional Bandwidth Optimized Using Feed Forward Back Propagation ANN

An Artificial Neural Network (ANN) based Substrate Integrated Waveguide Band Pass Filter (SIW BPF) is proposed in this paper. A Feed Forward Back Propagation Neural Network (FF-BP NN) is utilized to optimize the filter dimensions. The Gradient Descent with Momentum and Adaptive Learning Rate algorithm is used to train the network at a learning rate of 0.01. The high pass characteristics of the SIW is converted into band pass by incorporating U slots on its top plane. Defected Ground Structure (DGS) is utilized in the bottom plane to improve the impedance matching. To validate, the prototype is fabricated using RT/Duroid 5880 and tested. The proposed filter has a center frequency at 14.68 GHz with a wide pass band from 12.92 to 16.43 GHz with a 3-dB Fractional Bandwidth (FBW) of 24%, return loss more than 20 dB and insertion loss of about 1.9 dB within the pass band. The filter has a small dimension of about 0.63 λ g 2 , where λ g is the guided wavelength at the center frequency. This filter offers wide passband, smaller size, low insertion loss, good return loss and it is useful in Ku-band satellite communication applications.

Crystal Plane-Related Oxygen-Evolution Activity of Single Hexagonal Co3 O4 Spinel Particles.

The electrocatalytic activity for the oxygen evolution reaction in alkaline electrolyte of hexagonal spinel Co3 O4 nanoparticles derived using scanning electrochemical cell microscopy (SECCM) is correlated with scanning electron microscopy and atomic force microscopy images of the droplet landing sites. A unique way to deconvolute the intrinsic catalytic activity of individual crystal facets of the hexagonal Co3 O4 spinel particle is demonstrated in terms of the turnover frequency (TOF) of surface Co atoms. The top surface exposing 111 crystal planes displayed a thickness-dependent TOF with a TOF of about 100 s-1 at a potential of 1.8 V vs. RHE and a particle thickness of 100 nm. The edge of the particle exposing (110) planes, however, showed an average TOF of 270±68 s-1 at 1.8 V vs. RHE and no correlation with particle thickness. The higher atomic density of Co atoms on the edge surface (2.5 times of the top) renders the overall catalytic activity of the edge planes significantly higher than that of the top planes. The use of a free-diffusing Os complex in the alkaline electrolyte revealed the low electrical conductivity through individual particles, which explains the thickness-dependent TOF of the top planes and could be a reason for the low activity of the top (111) planes.

Highly sensitive tunable terahertz absorber for biosensing applications

A multicontrollable terahertz perfect absorber has been proposed and demonstrated numerically through an L-shaped metasurface tri-layer structure. The proposed tri-layer structure comprises a top L-shaped InAs layer and gold ground plane separated by a dielectric polyimide layer which shows a perfect absorption of more than 99.8% with the application of magnetic field from 0.5–0.8 T along with a higher tunability rate of 0.76 THz/T in the frequency spectrum. The multicontrollability and tunability in the frequency response are achieved by the application of a magnetic field as well as the geometrical rotation of meta-atom. Thus, the proposed structure act as a bicontrollable metasurface providing an efficient approach for control over the maximum absorptance frequency. Furthermore, the performance of the proposed absorber shows greater applicability for the bio-chemical sensors with a high value of sensitivity of around 1109 GHz/RIU for the detection of different chemicals, 1012 GHz/RIU for different pathogens, and 1066 GHz/RIU for different hemoglobin concentrations. Thus, the proposed metasurface provides a bicontrollable approach for efficient absorption and prevents transmission as well as acts as multifunctional metasurface which provides potential applications in designing bio-chemical sensors at terahertz frequency regimes.

NONLINEAR FORCED CONVECTIVE HEAT TRANSFER IN A COMPOSITE AIR/POROUS LAYER WITH PERMEABLE TOP AND BOTTOM BOUNDARIES AND ENERGY SOURCE: DIFFERENT PENETRATION DEPTH OF PATTERNS

This paper deals with nonlinear convective heat transfer in a composite heat-generating air/porous system bounded by the top and bottom solid permeable planes of equal temperature and forced by a vertical throughflow. In the presence of a uniform energy source, penetrative convection originates over this throughflow. It is numerically simulated by the finite difference method and Newton's method. The paper extends previous studies by considering the evolution of the supercritical and subcritical nonlinear convective patterns of a different penetration depth, increasing the supercriticality &lt;i&gt;r&lt;/i&gt; from 0 to 2, P&amp;#232;clet number Pefrom - 6 to 5, and depth ratio &lt;i&gt;d&lt;/i&gt; from 0.05 to 0.20. The convection together with the basic throughflow contributes to the total heat transfer rate and improves thermal performance of the partial porous system. The case can find its application, for example, in storing the biologically active plant products releasing heat. The short-wave convection localized in the upper air layer appears over the upward throughflow with Pe &amp;#62; 0. Its relative contribution to the total heat flux is much smaller than that of the basic throughflow and decreases with increases in the values of Pe and &lt;i&gt;d&lt;/i&gt;. Both local and large-scale convective patterns can initiate over the downward throughflow with Pe &amp;#60; 0. Their relative contributions to the total heat flux grow with increasing the absolute values of Pe and &lt;i&gt;d&lt;/i&gt;. The large-scale convection that covers the air and porous layers at Pe &amp;#61; -6, &lt;i&gt;d &lt;/i&gt;&amp;#61; 0.05 enhances heat transfer more effectively than does the local one occurring within the air layer.

Electrical surface properties of nanoporous alumina membranes: influence of nanochannels' curvature, roughness and composition studied via electrokinetic experiments.

Among classical nanoporous oxide membranes, anodic aluminum oxide (AAO) membranes, made of non-connected, parallel and ordered nanochannels, are very interesting nanoporous model systems widely used for multiple applications. Since most of these applications involve local phenomena at the nanochannel surface, the fine description of the electrical surface behavior in aqueous solution is thus of primordial interest. Here, we use an original experimental approach combining several electrokinetic techniques (tangential and transverse streaming potential as well as electrophoretic mobility experiments) to measure the ζ-potential and determine the surface isoelectric points (IEPs) of several AAOs having different characteristic sizes and compositions. Using such an approach, all the different surfaces available in AAOs can be probed: outer surfaces (top and bottom planes), pore wall surfaces (i.e., inner surfaces) and surfaces created by the grinding of the AAOs. We find clear IEP differences between the outer, pore wall and ground surfaces and discuss these in terms of nanochannel and surface morphology (curvature and roughness) and of modifications of the chemical environment of the surface hydroxyl groups. These results highlight the heterogeneities between the different surfaces of these AAO membranes and emphasize the necessity to combine complementary electrokinetic techniques to properly understand the material, an approach which can be extended to many nanoporous systems.

Effect of modifiers on crystalizing habit and mechanical strength of α-hemihydrate gypsum prepared from PG by an autoclaved method

α-Hemihydrate gypsum (α-HH) was prepared by autoclaving phosphogypsum (PG) in the presence of potassium sodium tartrate, succinic acid, potassium sulfate and aluminum sulfate as modifiers. Through testing the crystal water content, XRD, XPS, SEM, and strength, and carrying out the molecular dynamic simulation, the effect and mechanism of modifiers on the crystalizing habit and mechanical strength of α-HHs was researched. The SEM pictures showed that, some α-HH crystals presented the form of fine grains, well-crystallized α-HHs were monoclinic and hexagonal and presented short column or long rod shape. The addition of modifiers obviously reduced the content of fine grains and the aspect ratio of well-crystallized crystals. The influence of modifiers on crystal morphology is related to the dehydration rate of PG, total conversion time of PG into α-HH, and selective adsorption of modifiers on crystal surface. Succinic acid and potassium sodium sulfate inhibited the dehydration of PG for 1 h, and extended the total conversion time to 5 h. The addition of potassium sulfate and aluminum sulfate did not change the induction period, only shortened the total conversion time to 3 h. The modifiers did not enter the structure of α-HH crystal, but preferentially absorbed on the plane of (111) and influenced the growth along the top plane. Considering the aspect ratio and content of well-crystallized crystals, succinic acid and potassium sodium tartrate had more significant effect than potassium sulfate and aluminum sulfate. The strengths could be improved by adding the modifiers, and the effect of succinic acid was the best. The flexural and compressive strengths of all α-HHs were greater than the values of 4.5 MPa and 30Mpa, and met the requirements of high strength gypsum of α30.

ANALISIS KEMAMPUAN MEMAHAMI SUMBU AFINITAS MENGGUNAKAN MAGIC STRAWS PADA MATERI IRISAN BIDANG PADA BANGUN RUANG

Learning material about plane slices in geometric shapes has prerequisite material for the affinity axis. An understanding of the affinity axis can be done with the help of magic straws. The purpose of this study is to provide alternative media to provide an understanding of the affinity axis for students who are constrained by limited computer equipment or computer equipment that is not qualified to install application programs that support learning. This research is a qualitative research. The instruments of this study were observation sheets on the ability to understand the affinity axis and interview guidelines for using magic straws in understanding the affinity axis. Data analysis technique is using data analysis techniques Miles and Huberman. The use of magic straws affects students' abilities regarding the affinity axis, the abilities obtained are students understanding 1) the concept of points that are in a plane, 2) to get an affinity axis, two points that are in a plane that can be connected, 3) a point can be connected with a point of yield an extension of the rib that is still in line with that point, the 4 affinity axes are not only on the base plane, but can also be on the top plane. There are several things that need to be considered, namely 1) selecting straight/not curved pipes when making cubes, 2) using cable ties to mark dots on the ribs so they don't interfere with the student's point of view, 3) when pulling two dots use mattress thread tightly/not loosely, 4) when you have obtained a plane section in the geometric shape, shade the section by connecting it using a mattress thread to the inside of the plane.

A modified AMC-based antenna sensor for contactless measurement of complex permittivity

The paper proposes a modified artificial magnetic conductor (M-AMC)-based antenna sensor for retrieving the complex permittivity of material under test (MUT). The antenna sensor measurement system is composed of a coplanar waveguide (CPW) antenna and a M-AMC structure. The M-AMC structure consists of a 3×3 array, and each unit cell is fabricated by two-layer dielectric substrates. The M-AMC unit cell is evolved from the traditional square unit one, and in each cell, four bent microstrip lines are embedded in the middle plane of M-AMC structure to connect the top square metallic patch through metallic holes. Compared with traditional AMC structure, the added bent microstrip line can increase the current path. Besides, four complementary split-ring resonators (CSRRs) are etched on the top plane of each unit to improve the density of electrical field. A large metallic patch covers the bottom plane of M-AMC. The resonant frequency of M-AMC structure is reduced a lot than the traditional one, which is beneficial to realize miniaturization. In measurement, the antenna is placed on the upper surface of M-AMC structure with an appropriate distance, and the MUT is placed on top plane of M-AMC. The MUTs with different thicknesses and complex permittivity will alter the resonant frequency and quality factor of the antenna sensor. Experiment is carried out to demonstrate the performances of proposed antenna sensor. An average sensitivity of 1.89 % is achieved and the maximum error is less than 3.516 % in extracting the real permittivity. All in all, the proposed antenna sensor has a potential superiority in the scope of material characterization.

Corrosion susceptibility of different planes of AlMgScZr alloy produced by selective laser melting

In this study, the corrosion susceptibility of the Top and Side plane of the AlMgScZr alloy manufactured by selective laser melting (SLM) was investigated by electrochemical tests. The microstructures indicated that an alternately fine and coarse grain could be found in the Top plane and Side plane. The Top plane was mostly dominated by fine grains, while the microstructure in the Side plane primarily consisted of columnar grains. The XRD and TEM results suggested a great deal of nano-size Al3(Sc, Zr) precipitations were formed in the Top and Side plane. Moreover, the results from the EBSD demonstrated that the texture of the Top plane was closed to {001}〈100〉 but very weak, while the Side plane orientated slightly {011}〈122〉 texture. The electrochemical tests showed that the Top plane exhibited a better corrosion resistance compared with the Side plane. The lower corrosion susceptibility of the Top was mainly attributed to the better grain distribution and weaker texture relative to the Side plane.

Compact LTCC millimeter wave bandpass filter with imbedded dielectric resonators

ABSTRACT A novel substrate-integrated low-temperature ceramic co-fired (LTCC) millimeter-wave bandpass filter operating in the Ka-band is proposed. The filter is composed of multiple layers of media and metal plane. The dielectric resonators (DRs) with high dielectric constant are embedded in LTCC dielectric cavity excavated in LTCC dielectric. The input/output (I/O) is exploited by the slot on metal plane feed by CPW （Co-Planar Waveguide）structure on the top and bottom metal planes, which make the filter able to be integrated to the other components. Simulations and measurements show that the filter has a center frequency of 35 GHz, a relative bandwidth of about 6%, an insertion loss of 1.25 dB, and a return loss of −15 dB in the passband. The filter has many advantages, such as high selectivity, wide bandwidth, low profile, small volume, and so on, which has high engineering application in 5G communications.

A surface-to-surface transition based UWB bandpass filter with triple in-band notches

A Compact Ultra-Wideband (UWB) bandpass filter (BPF) designed using the surface-to-surface transition mechanism and with triple passband transmission zeros (TZs) is proposed. The geometry of basic structure consists of two microstrip lines placed facing each other on the top plane coupled with a short circuited co-planar waveguide (CPW) in the bottom plane. This basic architecture develops a UWB response with two transmission zeros (TZs) at lower/higher passband edges, which exhibits good frequency characteristics. Later, complementary folded split ring resonator (CSRR), split ring resonators (SRRs) and folded split ring resonators (FSRRs) are appended to the basic architecture to generate triple passband notches so as to circumvent interferences. A hardware prototype is finally developed and its response tested against the simulated data. The triple-notched BPF is compact covering a physical area of only 14 × 11.4 mm2.

Chemical Vapor Deposition of High-Optical-Quality Large-Area Monolayer Janus Transition Metal Dichalcogenides.

One-pot chemical vapor deposition (CVD) growth of large-area Janus SeMoS monolayers is reported, with the asymmetric top (Se) and bottom (S) chalcogen atomic planes with respect to the central transition metal (Mo) atoms. The formation of these 2D semiconductor monolayers takes place upon the thermodynamic-equilibrium-driven exchange of the bottom Se atoms of the initially grown MoSe2 single crystals on gold foils with S atoms. The growth process is characterized by complementary experimental techniques including Raman and X-ray photoelectron spectroscopy, transmission electron microscopy, and the growth mechanisms are rationalized by first principle calculations. The remarkably high optical quality of the synthesized Janus monolayers is demonstrated by optical and magneto-optical measurements which reveal the strong exciton-phonon coupling and enable an exciton g-factor of -3.3.

Enhancement of heat and mass transfer by herringbone microstructures in a simple shear flow

The heat and mass transfer characteristics of a simple shear flow over a surface covered with staggered herringbone structures are numerically investigated using the lattice Boltzmann method. Two flow motions are identified. The first is a spiral flow oscillation above the herringbone structures that advect heat and mass from the top plane to herringbone structures. The second is a flow recirculation in the grooves between the ridges that advect heat and mass from the area around the tips of the structures to their side walls and the bottom surfaces. These two basic flow motions couple together to form a complex transport mechanism. The results show that when advective heat and mass transfer takes effect at relatively large Reynolds and Schmidt numbers, the dependence of the total transfer rate on Schmidt number follows a power law, with the exponent being the same as that in the Dittus–Boelter equation for turbulent heat transfer. As the Reynolds number increases, the dependence of the total transfer rate on the Reynolds number also approaches a power law, and the exponent is close to that in the Dittus–Boelter equation.

Complex geometry of volcanic vents and asymmetric particle ejection: experimental insights

Explosive volcanic eruptions eject a gas-particle mixture into the atmosphere. The characteristics of this mixture in the near-vent region are a direct consequence of the underlying initial conditions at fragmentation and the geometry of the shallow plumbing system. Yet, it is not possible to observe directly the sub-surface parameters that drive such eruptions. Here, we use scaled shock-tube experiments mimicking volcanic explosions in order to elucidate the effects of a number of initial conditions. As volcanic vents can be expected to possess an irregular geometry, we utilise three vent designs, two “complex” vents and a vent with a “real” volcanic geometry. The defining geometry elements of the “complex” vents are a bilateral symmetry with a slanted top plane. The “real” geometry is based on a photogrammetric 3D model of an active volcanic vent with a steep and a diverging vent side. Particle size and density as well as experimental pressure are varied. Our results reveal a strong influence of the vent geometry, on both the direction and the magnitude of particle spreading and the velocity of particles. The overpressure at the vent herby controls the direction of the asymmetry of the gas-particle jet. These findings have implications for the distribution of volcanic ejecta and resulting areas at risk.