Plane Ones Research Articles

Theoretical Dissection of Cation-Deficient Layered Ruddlesden-Popper Oxysulfide Perovskites with a High-Efficiency Carrier Transport Channel.

The search for lead-free perovskite materials has triggered intensive interest. Here, we study the electronic structures and optical properties of cation-deficient Ruddlesden-Popper oxysulfide perovskites Ln2Ti2O5S2 (Ln = Sc, Y, or La), with a tunable band gap of 1.45-2.1 eV and a small exciton binding energy of ∼0.1 eV, among which Y2Ti2O5S2 has been synthesized experimentally. Sc2Ti2O5S2 possesses the largest light absorbance in the visible region. We further rationalize the light absorption via the transition dipole moment and suggest potential applications of Sc2Ti2O5S2 in solar cells and Y2Ti2O5S2 and La2Ti2O5S2 in water splitting. In addition, this family exhibits small effective masses within the x-y plane and large ones along the z direction. Most importantly, electron gas-like carrier behaviors are observed within the Ti-O bond region, offering a diffusion channel for electron transport. These findings greatly advance our understanding of lead-free perovskites and offer a novel material platform for future optoelectronic devices.

An analytical approach for the determination of helical gear tooth geometry

Purpose This paper aims to present an analytical approach for the determination of helical gear tooth geometry and introduces the necessary parameters. Tooth geometry including tooth chamfer, involute curve, root fillet, helix as well as tooth microgeometry can be obtained using the presented approach. Design/methodology/approach The presented analytical approach involves deriving the equivalent equations at the transverse plane rather than the normal plane. Moreover, numerical evaluation of microgeometry modifications is presented for tooth profile, tooth lead and flank twist. Findings An analytical approach is presented and equations are derived and explained in detail for helical gear tooth geometry calculation, including tooth microgeometry. Method 1, which was presented by Lopez and Wheway (1986) for obtaining the root fillet, is examined and it is proven that it does not work accurately for helical gears, but rather it works perfectly in the case of spur gears. Changing the normal plane parameters in Method 1 to the transverse plane ones does not give correct results. Two alternative methods, namely, Methods 2 and 3, are developed in the current research for the calculation of the tooth root fillet of helical gears. The presented methods and also the numerical evaluation presented for microgeometry modification are examined against the geometry obtained from Windows LDP software. The results show very good agreement, and it is feasible to apply the approach using the presented equations. Originality/value In the gear design process, it is important to model the correct gear tooth geometry and deliver all related dimensions and calculations accurately. However, the determination of helical gear tooth geometry has not been presented adequately by equations to facilitate gear modelling. The detailed helical gear tooth root has been enveloped using software tools that can simulate the cutter motion. Deriving those equations, presented in this article, provides gear design engineers and researchers with the possibility to model helical gears and perform design calculations in a structured, applicable and accurate method.

Prevalence of Oral Habits in Dentalanomalies

There are a lot of oral habits in which are included even non-nutritional habits. The role of these habits has been evidenced in the development of different malocclusion in each plane, vertical, transversal and sagittal ones. The reason why habits can cause such problems is based on equilibrium theory. The main purpose of this study is to assess the prevalence of non-nutritional habits and their effect development of dental anomalies. The method of this study was descriptive in prospectively. Its duration was 20 months. The age of children taken in this study vary from 6 to 15 years old and was selected casually at clinics of “University of Mother of Good Council” and two private clinics. Results we were able to fill the questionnaires of 194 patients in which 50.3% of them were females and 43.1% of them were males. According to the age of children, there was a frequency of 46.7% of 6-10 years old children and 53.3% of 11-15 years old ones. Results on the frequency of non-nutritive habits were about 64% of fake pacifier usage, in which there was a variety of percentage of time when it was used. Meanwhile, thumb sucking resulted in 10.20 % of results, lip biting or sucking 7.10%. Conclusions: This group age was very often in predisposition to have such habits. Our results confirm the impact of these habits in the development of different malocclusions. We recommend applying preventive strategies so we can avoid the installation of these habits and such malocclusions.

Augmentation on Heat Transfer and Friction Factor in Three Sides Solar Air Heaters Having an Arrangement of Multi-V and Transverse Wire Roughness on the Absorber Plate

This paper present the experimental inquiry on heat transfer and friction features enrichment adopting new-fangled of three side’s synthetically rugged rectangular duct solar air heaters (SAHs). The roughened rectangular SAH ducts has been an arrangement of multi-v and transverse wire (top wall multi-v and two side walls transverse) covered with glass on three sides. It has various appliances such as crop drying, seasoning of timber, space heating, industrial purpose, etc. The rectangular duct used has a width to height ratio, W/H, equal to 8, relative raggedness pitch, P/e, wide-ranging from 10 - 25, relative raggedness height, e/D, varied from 0.018 – 0.042 and flow Reynolds number, Re, occupied from 3500 – 12,000 for fixed values of relative raggedness width, W/w, of 6 and an angle of attack, 𝛼, equal to 60°. The heat transmission and friction features of this roughened duct is compared with plane ones under identical working conditions. The maximum augmentation in heat transmission and friction feature is identified to be 6.42 and 6.44 times over the smooth duct respectively. The enhancement in air temperature streaming under three side’s synthetically rugged SAH duct is found to be 54.47% more than that of the smooth one. Three side’s artificially rugged rectangular duct SAHs are preferable over plane ones collectively and tentatively

An Ultrawideband and High-Gain Antenna Based on 3-D Impedance-Matching Metamaterial Lens

In this article, we present an ultrawideband and high-gain antenna based on a 3-D impedance-matching metamaterial (IMM) lens. First, we design a 3-D IMM lens which can convert spherical-like waves to plane ones and is nearly perfect impedance-matching with the free space. To realize the 3-D lens, we propose and design two kinds of ultrawideband sandwich-structured metamaterial unit cells that can cover the refraction index ranges from 1.25 to 1.4 and from 1.4 to 3.8, respectively. We also design a double-ridged pyramid horn antenna as an ultrawideband feed source. Measured results verify that the presented lens antenna can work in an ultrawide bandwidth from 5.2 to 15.13 GHz, and the relative bandwidth is 97.7%. Moreover, it achieves a high aperture efficiency of more than 66% from 5.2 to 14.3 GHz, with a relative bandwidth of 93.3%. A maximum aperture efficiency of 85.6% is obtained at 11.5 GHz. The proposed lens antenna has an average of 2 dB gain enhancement versus optimal horn with the same aperture area. And the length of the lens antenna reduces to 22% compared to a bare horn antenna with the same gain and aperture efficiency.

Modeling Nonstationary Gas-Free Combustion Processes with Account of Sample Structure Heterogeneity

A model of nonstationary gas-free combustion has been formulated with account for the structure heterogeneity and for the temperature dependence of diffusion with the use of two models of reaction cells: plane and spherical ones. Numerical simulation of the propagation of the self-propagating high-temperature synthesis (SHS) wave and a comparative analysis of the SHS wave propagation velocity was carried out with the use of two models of reaction cells. The numerical investigations have shown that with the use of the model of spherical reaction cells the SHS wave propagation velocity is higher than for plane cells by 1.7 times. Dependences of the rate of combustion on the characteristic value of the heterogeneous structure of a sample have been obtained. The computational–theoretical values of the SHS wave propagation velocity coincide with good accuracy with experimental data in a wide range of the dimension of the heterogeneous structure of SHS.

Atomic-scale characterization of interfaces between 2A70 aluminum alloy matrix and Cu-enriched layer after electropolishing

The formation of a Cu-enriched layer in Al-Cu alloy upon corrosion has been widely recognized. However, the detailed compositional, structural and interfacial information of this solute enrichment behavior has been ambiguous. Herein, we report on an atomic-scale Cs-corrected scanning transmission electron microscopy (STEM) study on 2A70 aluminum alloy subject to electropolishing, in order to unveil the ambiguities concerning the Cu enrichment. A 2-nm-thick Cu-enriched θ′ phase layer, has been observed underneath the amorphous layer. Three kinds of interfaces between the Al matrix and this layer are observed along different crystalline directions from plane (110), including coherent and semicoherent ones.

CVD growth of zinc oxide thin films on graphene on insulator using a high-temperature platinum-catalyzed water beam

The characteristics of zinc oxide (ZnO) films with different thicknesses grown on graphene, i.e., single-layer graphene (SLG) and multilayer graphene (MLG), on insulators at 500 °C using a reaction between dimethylzinc and high-temperature water generated by a catalytic reaction on Pt nanoparticles were investigated. The growth rate of continuous ZnO layer on MLG was higher than that of SLG. XRD patterns for the ZnO films exhibited an intense diffraction peak associated with (0002) plane and small ones associated with (10–10) and (10–11) planes, suggesting the grown hexagonal wurtzite ZnO is not perfectly along c-axis direction due to the nature of the used graphene structures. The FWHM values of the 2θ for ZnO (0002) were < 0.20° and 0.16° for ZnO on SLG and MLG, respectively. The photoluminescence at room temperature exhibited strong emission peak at 3.28 eV with no significant level of green emission indicating negligible defect density in the grown ZnO films. The results suggest that accurate optical bandgap cannot be determined from the transmittance spectra for the ZnO films with thickness and roughness higher than 1 µm and 20 nm, respectively. The results also suggest that the thickness of ZnO films should be below 1 µm in order to obtain acceptable level of transmittance in visible up to near infrared region.

Quantitative assessment of wideband antenna geometry modifications for size-reduction-oriented design

Incorporation of various topological modifications to basic antenna structures is a common strategy in the context of size-reduction-oriented design. Modifications can be applied to the ground plane, the feed line, and/or antenna radiator, and may lead to achieving smaller physical dimensions of the antenna at hand. Unfortunately, various topology alteration options are normally reported on a case-to-case basis; systematic comparisons of different modification types are lacking in the literature. In this paper, thorough investigations of selected topological changes in terms of their effect on antenna size reduction are carried out. Numerical experiments are performed using two ultra-wideband monopoles. In order to ensure a fair comparison, for each antenna topology, all geometry parameters are rigorously optimized to obtain the minimum footprint while maintaining acceptable electrical performance. The results clearly indicate the advantage of feed line modifications (56% average physical size reduction) over a ground plane and radiator ones (43% and 2.15% respectively). Experimental validations confirming the numerical findings are also provided.

Influence of baffle configurations on flow and heat transfer characteristics of unilateral type helical baffle heat exchangers

The flow and heat transfer performances were investigated on unilateral ladder type helical baffle heat exchangers (ULHBHXs) with different geometrical structures in half cylindrical space and compared with those of the segmental baffle heat exchangers (SBHXs). The unilateral ladder type helical baffles consist of two alternate groups of plates, the folded baffles (Baffles A) and the segment ones (Baffles B). The studied ULHBHXs include the combination schemes of different Baffle A with different baffle pitches (40, 60, 80 mm) and different projection length of inclined section (l = 60, 72, 84 mm and a plane one). Visualization methods of nephograms were adopted on special slices to clearly reveal the impacts of baffle configurations on flow patterns. The numerical results show that the shell-side heat transfer coefficients of the ULHBHX schemes with folded Baffles A are superior but the comprehensive indexes are inferior to those of the corresponding plane ones, and all the helical schemes are superior to those of the segmental schemes. The average ratios of shell-side heat transfer coefficient, pressure drop and comprehensive indexes hoΔpo−1 and hoΔpo−1/3 of all the twelve ULHBHX schemes over those of the SBHX ones with corresponding baffle pitches are 1.166, 0.670, 1.851 and 1.352, respectively.

Soundproof Characteristics of Zigzag-Shaped Panel on Site

A transparent sound-proof panel which was zigzag shaped was developed and tested of its effects for installed with 20 m extension on site. The reflected and diffracted sound were measured for travelling and fixed noise. The noise barrier was tested not only for plane panel, but also mixed composition which was combined shaped and plane ones. In result, the shaped barrier showed average 1.01 dBA for the SUV travelling vehicle. For fixed noise, increased effects for reflected sound was for distant source, especially, 1.18 dBA for 3 m distance from installed noise barrier. Key words: Noise Barrier, Traffic Noise, On-Site Soundproof, Shaped Panel

Facile and controllable preparation of different SBA-15 platelets and their regulated drug release behaviours

Based on the simplest TEOS/P123/HCl(aq.) templating system, it is demonstrated in this work that different SBA-15 platelets can be controllably prepared via the partitioned cooperative self-assembly (PCSA) process without using any additives or complicated procedures. Experimental results show that the reduced amounts of TEOS added in the 2nd additions in the PCSA process play a determining role in transforming the SBA-15 platelet morphologies from the plane ones to a unique kind of UFO-shaped ones. The obtained SBA-15 platelets, plane or UFO-shaped ones, are composed of plugged mesochannels aligned in a 2D hexagonal symmetry, with neighboring channels connected by large tunnel holes (intrawall pores). Different platelet morphologies and their evolution were found to be dependent on partitioning conditions (2nd TEOS addition and interval time). A competitive process involving the aggregation of SBA-15 primary particles dictates the formation of SBA-15 particles with different morphologies, meanwhile the UFO-shaped SBA-15 platelets (U-SBA-15P) can be deemed as intermediate ones between rod-like particles and plane platelets. Moreover, upon the release of indometacin (IMC) in simulating intestinal fluid, UFO-shaped SBA-15 platelets show faster drug release performance compared with their plane counterparts or conventional SBA-15 fibers. The larger the protruded areas in UFO-shaped platelets, the higher the release rate will be. This work, as we believe, presents a new strategy to regulate drug releasing performance by simply tuning particle morphologies of SBA-15 platelets and can allow rational design of IMC/meso-silica formulations.

Magnetic and magneto-optical characteristics of spin coated Co0.6Zn0.4Fe1.7Mn0.3O4 thin films on Pt (111) coated Si substrate

Abstract This paper reports magnetic and magneto-optical properties of Co0.6Zn0.4Fe1.7Mn0.3O4 nanocrystalline thin films (thickness ∼140–200 nm) deposited on Pt (1 1 1)/Ti/SiO2/Si substrates by spin coating technique. Deposited films are then annealed at 600 °C and 700 °C for 60 min (significant reduction in film thickness from 200 nm to 140 nm was noted with the increase in post deposition annealing temperature). The X ray diffraction patterns confirmed the spinel cubic structure of Co0.6Zn0.4Fe1.7Mn0.3O4 films with polycrystalline phase and also indicated a partial texture orientation. Deposited films showed magnetic anisotropy as evidenced from magnetic and magneto-optical measurements. Higher in plane remnant magnetization and low coercivity values as compared to out of plane ones were observed for both samples, indicating in plane alignment of easy axis of magnetization.

Dynamics of plasma−dust structures formed in a trap created in the narrowing of a current channel in a magnetic field

The geometry and dynamics of plasma−dust structures in a longitudinal magnetic field is studied experimentally. The structures are formed in a glow-discharge trap created in the double electric layer produced as a result of discharge narrowing by means of a dielectric insert introduced in the discharge tube. Studies of structures formed in the new type of glow-discharge trap are of interest from the standpoint of future experiments with complex plasmas in superstrong magnetic fields in which the dust component is magnetized. Different types of dielectric inserts were used: conical and plane ones with symmetric and asymmetric apertures. Conditions for the existence of stable dust structures are determined for dust grains of different density and different dispersity. According to the experimental results, the angular velocity of dust rotation is ≥10 s–1, which is the fastest type of dust motion for all types of discharges in a magnetic field. The rotation is interpreted by analyzing the dynamics of individual dust grains.

Molecular modeling of the effects of 40Ar recoil in illite particles on their K–Ar isotope dating

The radioactive decay of 40K to 40Ar is the basis of isotope age determination of micaceous clay minerals formed during diagenesis. The difference in K–Ar ages between fine and coarse grained illite particles has been interpreted using detrital-authigenic components system, its crystallization history or post-crystallization diffusion. Yet another mechanism should also be considered: natural 40Ar recoil. Whether this recoil mechanism can result in a significant enough loss of 40Ar to provide observable decrease of K–Ar age of the finest illite crystallites at diagenetic temperatures – is the primary objective of this study which is based on molecular dynamics (MD) computer simulations.All the simulations were performed for the same kinetic energy (initial velocity) of the 40Ar atom, but for varying recoil angles that cover the entire range of their possible values. The results show that 40Ar recoil can lead to various deformations of the illite structure, often accompanied by the displacement of OH groups or breaking of the Si–O bonds. Depending on the recoil angle, there are four possible final positions of the 40Ar atom with respect to the 2:1 layer at the end of the simulation: it can remain in the interlayer space or end up in the closest tetrahedral, octahedral or the opposite tetrahedral sheet. No simulation angles were found for which the 40Ar atom after recoil passes completely through the 2:1 layer. The energy barrier for 40Ar passing through the hexagonal cavity from the tetrahedral sheet into the interlayer was calculated to be 17kcal/mol. This reaction is strongly exothermic, therefore there is almost no possibility for 40Ar to remain in the tetrahedral sheet of the 2:1 layer over geological time periods. It will either leave the crystal, if close enough to the edge, or return to the interlayer space. On the other hand, if 40Ar ends up in the octahedral sheet after recoil, a substantially higher energy barrier of 55kcal/mol prevents it from leaving the TOT layer over geological time.Based on the results of MD simulations, the estimates of the potential effect of 40Ar recoil on the K–Ar dating of illite show that some of 40Ar is lost and the loss is substantially dependent on the crystallite dimensions. The 40Ar loss can vary from 10% for the finest crystallites (two 2:1 layers thickness and <0.02μm in diameter) to close to zero for the thickest and largest (in the ab plane) ones. Because the decrease of the K–Ar estimated age is approximately proportional to the 40Ar loss, the finer crystallites show lower apparent age than the coarser ones, although the age of crystallization is assumed equal for all the crystallites. From the model it is also clear that the lack of K removal from illite fringes (potentially Ar-free) strongly increases the apparent age differences among crystallites of different size.

Effects of submerged sheet pile vanes on mobile river beds

Submerged vanes are low-height flow-training structures emerging from the riverbed with a suitable angle of attack to the incoming flow. These structures redirect the stream flow and modify erosion and depositional rates in the bottom and in the banks of a river as a result of the secondary currents generated by their installation. For this reason they have many applications in river hydraulics for controlling river bed morphology. An experimental investigation is carried out to compare the efficiency of sheet-piling vanes versus thin plane ones in controlling sediment redistribution in the channel bed. In particular, experimental tests were carried out within a straight water channel, in conditions of bed load motion. The morphology of the river bed both in the area close to the structure and in the far field was examined at different angles of attack of the vane to the incoming flow and at different values of the submergence parameter, which is the ratio between the height of the water above the structure and the water level. The experimental results show that both the shape of the vanes as well as the angle of attack affect their performance in terms of the effects on the bed morphology, especially for greater submergence parameters. Specifically, plane and sheet-piling vanes produce comparable remodelings of the channel bed in the downstream region, but when the attack angle is increased, the thin plane vane causes deeper scour holes close to the structure. This last effect is probably due to the increased erosive capacity of the horseshoe vortex associated with the plane vane, while the uneven surface of the sheet-piling vane mitigates the erosive strength of that vortex.

Interaction of inner and outer layers in plane and radial wall jets

Large eddy simulations of turbulent radial and plane wall jets were performed at different Reynolds numbers using the Lagrangian dynamic eddy viscosity subgrid-scale model. The results were validated with experimental data available in the literature. Compared to the plane ones, the radial wall jets have an extra direction for expansion, which causes faster decay rates. Thus, the resulting pressure gradient distributions are different. However, the comparison of the results with the turbulent boundary layers under adverse and favourable pressure gradients reveals that these pressure gradients are not strong enough to cause any fundamental physical difference between plane and radial wall jets. In both cases, the local Reynolds number is an important determining factor in characterisation of the flow. The joint probability density function analysis shows that the local Reynolds number determines the level of intrusion of the outer layer into the inner layer: the lower the local Reynolds number, the stronger is the interaction of the inner and outer layers. These results can be used to clarify the scatter of the reported log-law constants in the literature.

Ising-type magnetic anisotropy and single molecule magnet behaviour in mononuclear trigonal bipyramidal Co(ii) complexes

The magnetic anisotropy of two pentacoordinate trigonal bipyramidal (C3v symmetry) Co(II) complexes, [Co(Me6tren)Cl]ClO4 (1) and [Co(Me6tren)Br]Br (2), was investigated and analysed by magnetic studies, high field multifrequency electron paramagnetic resonance (EPR) and ab initio calculations. Negative D parameters expressing an Ising-type anisotropy (easy axis of magnetization) were found experimentally for both complexes. Calculations led to D values very close to the experimental ones, which allows a robust rationalisation of the magnetic anisotropy in these complexes. The wavefunctions of the ground and the first four excited states reveal that they are strongly multideterminantal i.e. linear combinations of several determinants. The most important contribution to the spin orbit coupling between the ground and lowest excited states stabilizes the largest MS = ±3/2 components of the S = 3/2 state and therefore brings a large negative contribution to D. The analysis of the difference between the magnitudes of the anisotropy of the two complexes led to the conclusion that a large Ising anisotropy is preferred when weak σ-donating ligands are in the equatorial plane and strong π-donating ones are in axial positions; thus providing an efficient tool to chemists to predict the magnetic anisotropy in these types of complexes. The investigation of the magnetic behaviour of a single crystal of 1 by micro-SQUID shows, as expected, the presence of an easy axis of magnetization. The magnetic behaviour is consistent with quantum tunnelling of the magnetization mediated by intermolecular three-dimensional antiferromagnetic exchange interactions. Upon dilution of the Co(II) molecules in the isostructural Zn(II) compound, a blocking of the magnetization below 2 K is demonstrated; it results in an opening of the magnetization hysteresis loop in zero applied magnetic field.

EXPLICIT EXPRESSIONS FOR PRESSURE IN ACOUSTIC WAVES MULTIPLY REFLECTED FROM REFLECTING SURFACES OF CANONICAL FORM

In fra mework of the geometrical diffraction theory, the explicit expressions for the pre s sure in waves arbitrarily re reflected N times from a contour, boundary surfaces of the cylindrical and spherical refle c tors are obtained. Pressure expressions in the recept ion point for reflectors of the canonical form are obtained on the basis of 2D and 3D sol utions to the problems on the pressure determination in the acoustical wave re - reflected from a set of reflectors in the case of high - frequency oscillations. The pro blem in its general formulation is studied on the basis of a modified physical diffraction of Kirchhoff diffraction theory. Within the frames of the proposed modification , diffraction int egrals which leading terms for asymptotic expansions are studied throug h the multidimensional stationary phase tec h nique, are obtained. The developed analytical expressions for the pressure in the re - reflected wave conform to the GTD. For all three cases, these expressions are connected with calculating the N - th order dete r mi nant (in the 2D case), and of the 2N - th order determinants (for reflectors in 3D space). An analytical and numerical analysis of the obtained expressions versus distances between a source and a receiver from the reflecting surfac e is pe rformed. The acousti c wave focusing points are marked. The problem of replacing non - plane reflectors by plane ones in the applied problems of acoustics is discussed.

Anisotropy of energy losses in high-current Z-pinches produced by the implosion of cylindrical tungsten wire arrays

Results are presented from measurements of the anisotropy of energy losses in high-current Z-pinches produced by the implosion of wire arrays at the ANGARA-5-1 facility at load currents of up to 4MA. The energy losses were measured in the radial direction and along the pinch axis from the anode side. The main diagnostics were time-integrated thermocouple calorimeters, nanosecond X-ray diodes (XRDs) with different filters, and a foil radiation calorimeter with a time resolution of 2 μs. The azimuthal anisotropy of energy losses was measured for different wire array configurations and different shapes of the high-voltage electrode. The presence of strong initial azimuthal inhomogeneity of the wire mass distribution (sectioned arrays), as well as the use of conical electrodes instead of plane ones, does not increase the azimuthal inhomogeneity of the total energy losses. For cylindrical wire arrays, energy losses in the radial direction are compared with those along the pinch axis. According to XRD and calorimetric measurements, the radiation yield per unit solid angle along the pinch axis is two to three times lower than that in the radial direction. In the axial direction, the energy flux density of the expanding plasma is two to three times lower than the radiation intensity. The measured radiation yield across the pinch is 2.5–5 kJ/sr, while that along the pinch axis is 1–2 kJ/sr. The results obtained by means of XRDs agree to within measurement errors with those obtained using the radiation calorimeter. It is found that the energy per unit solid angle carried by the expanding plasma in the radial direction does not exceed 10% of the soft X-ray yield. Analysis of the structure of time-integrated pinhole images and signals from the radial and axial XRDs shows that radiation emitted in the radial direction from the hot central region of the pinch is partially screened by the less dense surrounding plasma halo, whereas radiation emitted in the axial direction is a superposition of the emissions from the hot dense central region of the pinch and the colder less dense peripheral plasma.