Convex Edge Research Articles

Numerical investigation of the refractive properties of near-horizontal rocky shore platforms and their effects on harmonic and stationary wave patterns

Near-horizontal shore platforms display highly irregular plan shapes, but little is known about the way in which these irregularities influence the significant wave height (Hŝ) on the platforms and the frequency components of the nearshore wavefield. As ocean waves share akin refractive properties to light rays, it can be assumed that, similarly to optical lenses, shore platforms can separate waves according to their frequency depending on their geometry. Thus, we use a non-linear Boussinesq wave model to conduct harmonic and bispectral mode decomposition analyses to study the control of concave and convex platform edges over wind waves (WW: 0.125–0.33 Hz), swell waves (SW: 0.05–0.125 Hz) and infragravity (IG: 0.008–0.05 Hz) waves frequencies. For breaking and non-breaking waves, increasing the platform edge concavity intensified wave divergence and subsequent attenuation of SW and IG across the outer platforms, reducing Hŝ by up to 25 %. Increasing the platform edge convexity intensified focusing and amplification of SW and WW over the outer platforms, increasing Hŝ by up to 18 % and 55 % for breaking and non-breaking waves. In the presence of breaking, IG amplification was affected by wave divergence across the inner platform, a condition determined by a critical convex curvature threshold (K=1.8) balancing wave focusing from refraction and defocusing from breaking. We find that convex curvature can determine the relative dominance of WW, SW and IG across platforms. Alongshore, coherent wave interactions governed IG stationary patterns defined by a node near the platform centreline and two antinodes on either side of concave edges. A node was generated at the platform centreline, and two antinodes were observed on either side of the convex edges for K>1.8, with the opposite pattern observed for K<1.8. Such patterns likely result in alongshore variations in wave-generated currents and erosion shaping rock coasts.

Fabrication of Circular Defects in 2-Dimensional Photonic Crystal Lasers with Convex Edge Structure

We have developed circular defects in 2-dimensional photonic crystal lasers that allow current injection for interconnected optical communications. However, when cleaving the sample to measure the output light, the output light intensity changes due to the cleaving position. In a previous study, we proposed a new end face structure called a convex edge structure. In this paper, we design the electron beam lithography patterns to fabricate this structure. With this design, it is possible to eliminate the effect of different cleaving positions and ensure that the cleavage tolerance is larger than the cleavage position error. We also develop the fabrication technology for this structure, fabricate samples, and measure the output light experimentally. The optical properties of the fabricated sample are similar to well-fabricated samples with normal cleavage edge faces. We are assured that these results contribute to future work such as accurate manufacturing and improving the end face configuration to obtain higher outputs.

Impact of Rh, Ru, and Pd Leads and Contact Topologies on Performance of WSe2 FETs: A First Comparative Ab Initio Study.

2D field-effect transistors (FETs) fabricated with transition metal dichalcogenide (TMD) materials are a potential replacement for the silicon-based CMOS. However, the lack of advancement in p-type contact is also a key factor hindering TMD-based CMOS applications. The less investigated path towards improving electrical characteristics based on contact geometries with low contact resistance (RC) has also been established. Moreover, finding contact metals to reduce the RC is indeed one of the significant challenges in achieving the above goal. Our research provides the first comparative analysis of the three contact configurations for a WSe2 monolayer with different noble metals (Rh, Ru, and Pd) by employing ab initio density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods. From the perspective of the contact topologies, the RC and minimum subthreshold slope (SSMIN) of all the conventional edge contacts are outperformed by the novel non-van der Waals (vdW) sandwich contacts. These non-vdW sandwich contacts reveal that their RC values are below 50 Ω∙μm, attributed to the narrow Schottky barrier widths (SBWs) and low Schottky barrier heights (SBHs). Not only are the RC values dramatically reduced by such novel contacts, but the SSMIN values are lower than 68 mV/dec. The new proposal offers the lowest RC and SSMIN, irrespective of the contact metals. Further considering the metal leads, the WSe2/Rh FETs based on the non-vdW sandwich contacts show a meager RC value of 33 Ω∙μm and an exceptional SSMIN of 63 mV/dec. The two calculated results present the smallest-ever values reported in our study, indicating that the non-vdW sandwich contacts with Rh leads can attain the best-case scenario. In contrast, the symmetric convex edge contacts with Pd leads cause the worst-case degradation, yielding an RC value of 213 Ω∙μm and an SSMIN value of 95 mV/dec. While all the WSe2/Ru FETs exhibit medium performances, the minimal shift in the transfer curves is interestingly advantageous to the circuit operation. Conclusively, the low-RC performances and the desirable SSMIN values are a combination of the contact geometries and metal leads. This innovation, achieved through noble metal leads in conjunction with the novel contact configurations, paves the way for a TMD-based CMOS with ultra-low RC and rapid switching speeds.

Limited linear source approximation with edge detection for convergence stability of method of characteristics

ABSTRACT A new implementation of the limited linear source approximation (LLSA) is proposed. The LLSA was previously proposed to eliminate local negative source in flux regions to mitigate numerical instability of the method of characteristics (MOC) with linear source approximation (LSA). In the present LLSA implementation, the convex edges of flux regions are used to check the local negative source to decrease the computational load. The present method is implemented in the transport code GENESIS, and its effectiveness is verified through the two dimensional C5G7 benchmark problem and the simplified two-dimensional high-temperature engineering test reactor core. The calculation results indicate that the present LLSA implementation efficiently mitigates the numerical instability of MOC with LSA. Additional computational time is less than 1% of total computation time.

Spot size measurement of a deuterium-tritium dense plasma focus using neutron radiography.

Neutron radiography is a technique uniquely suited to applications in nuclear diagnostics, non-destructive testing, and subcritical experiments. The spatial resolution of neutron radiographs is degraded by optical blur in the imaging system and the neutron source size, where the ideal source is point-like to optimize the point-spread function. A potential neutron source for radiography is the dense plasma focus (DPF), a coaxial Z-pinch that produces thermonuclear and beam-target neutrons. To assess if the source size is suitable for radiography, a neutron imaging system was used to measure the source size of the 4 MA Sodium DPF at the Nevada National Security Site operating with deuterium-tritium gas-fill. The source size was measured using the edge-spread function of tungsten objects, each having a rolled (convex) edge. The spot size was found to be 7-12mm full-width at half-max(FWHM) assuming a Gaussian source, though comparison is presented for Lorentzian and Bennett distributions. The average FWHM was found to be 8.6 ± 1.2mm vertically and 10.8 ± 1.2mm horizontally with respect to the image plane, averaging over varied edges and alignments. The results were sensitive to source alignment and edge metrology, which introduced notable uncertainties. These results are consistent with separate experimental measurements as well as magnetohydrodynamics simulations of this DPF, which suggest that neutron production can originate from pinches ∼5-7mm off-axis. These results suggest that the DPF should be used for radiography at low magnification (M < 1) where spot size does not dominate spatial blur.

Computational study of shock diffraction over convex edges

Numerical analysis of normal shock diffraction over various step corners is presented using an implicit second-order upwind least squares cell-based method. Slipstream angle calculation for various corner angles and Mach numbers, variation of pressure load and specific heat flux with incident shock Mach numbers and different step corners along the step wall, separation point movement, and reattachment of the streamlines are some of the key features of the present study. Detailed studies have been conducted about the perturbed region enclosed within the diffracted shock wave and the last running expansion wave with the increase in the incident shock Mach numbers. The finite Volume Method is used to solve the governing equations numerically for the simulation of the moving shock. Various flow characteristics such as secondary shock, contact surface, expansion wave, slipstream, vortex, etc are well captured. Apart from isopycnics; Mach contours, isobars, and isotherms are plotted as well. The reattachment region formed after the flow separation near the step edge is mentioned and corresponding lengths over various steps are presented. Separation point movement along the step wall is highlighted and a relevant increase in reattachment length is reported. The slipstream angles get increased with incident shock Mach numbers and with corner angles. However, the rate of increment of slipstream angle decreases gradually. The core of the vortices generated and the reattachment of the separated streamlines are indicated by the two downfalls in the heat flux values.

Preparation of convex edges in fused silica by single pass perforation with a 2D Airy-Gaussian beam.

Following ultrafast laser machining of fused silica, post-processing such as polishing and honing are typically required for edges. In this study, we employed a spatial light modulator (SLM) to generate the 2D Airy-Gaussian beam to prepare the convex edges in fused silica by using a single pass of a picosecond laser. It is found that, if the speed exceeds 5mm/s, there would be plasma interference which is unfavorable for the separation process. A filament effect was observed when the internal laser peak power exceeds the damage threshold of fused silica. The shape of the convex edges was consistent with the propagation path of the 2D Airy-Gaussian beam inside the fused silica before separation. The inclination angle was 17° and 13°, respectively, on the upper and lower end of the edges. The results of this study provide a new, to our knowledge, method for the preparation of curved structures with different curvatures in transparent materials.

Active Osteoblasts or Quiescent Bone Lining Cells? Preosteoblasts Fate Orchestrated by Curvature and Stiffness of an In Vitro 2.5D Biomimetic Culture System.

Biomimetic cell culture systems are required to provide more physiologically relevant microenvironments for bone cells. Here, a simple 2.5D culture platform is proposed, combining adjustable stiffness and surface features that mimic bone topography by using sandpaper grits as master molds with two stiffness formulations of polydimethylsiloxane (PDMS). The subsequent replicas perfectly conform the grits and reproduce the corresponding negative relief with cavities separated by convex edges. Biomimicry is also provided by an extracellular matrix (ECM)-like thin film coating, using the layer-by-layer (LbL) method. The topographical features, alternating concave, and convex structures drive preosteoblasts organization and morphology. Strikingly, curvature orchestrates the commitment of preosteoblasts, with i) maturation to active osteoblasts able to produce a dense collagenous matrix that ultimately mineralizes in the cavities, and ii) edges hosting quiescent cells that synthetize a very thin immature collagen layer with no mineralization. In summary, the present in vitro culture system model offers a cell-instructive 2.5D microenvironment that controls preosteoblasts fate, leading to two coexisting subpopulations: mature osteoblasts and bone lining cells (BLC). This promising culture system opens new avenues to advanced tissue-engineered modeling and can be applied to precellularized bone biomaterials.

Fast diffraction model of an EUV mask based on asymmetric patch data fitting.

Calculating the diffraction near field (DNF) of a three-dimensional (3D) mask is a key problem in the extreme ultraviolet (EUV) lithography imaging modeling. This paper proposes a fast DNF model of an EUV mask based on the asymmetric patch data fitting method. Due to the asymmetric imaging characteristics of the EUV lithography system, a DNF library is built up including the training mask patches posed in different orientations and their rigorous DNF results. These training patches include some representative local mask features such as the convex corners, concave corners, and edge segments in four directions. Then, a convolution-based compact model is developed to rapidly simulate the DNFs of 3D masks, where the convolution kernels are inversely calculated to fit all of the training data. Finally, the proposed model is verified by simulation experiments. Compared to a state-of-the-art EUV mask model based on machine learning, the proposed method can further reduce the computation time by 60%-70% and roughly obtain the same simulation accuracy.

Visualization and analysis of the impinging spray and combustion characteristics in a lateral swirl combustion system (LSCS)

A lateral swirl combustion system (LSCS) was proposed to improve the fuel/air mixing and combustion processes, and previous results have validated its excellent combustion performance in direct injection diesel engines. To further explore the fuel/air mixture mechanism of the LSCS, the effects of convex edge height ha = 2–8 mm (corresponding to interferential angle δ = 133°-14°) on the impinging spray and flame were investigated visually in a constant volume combustion system employing high-speed shadowgraph, direct photography and two-color methods. The experimental results suggested that the combustion chamber with ha = 6 mm (δ = 48°) exhibited superior results in terms of total spray area and combustion. Regardless of whether ha increased or decreased from 6 mm, all of which impaired the synthesis result of the wall-flow-guided and interferential effects. Specifically, when the ha was 2 mm, the wall-flow-guided effect was decreased, and the excessive δ corresponding to 133° caused the neighboring wall jets to approximate a head-on collision, which inevitably resulted in the part of fuel accumulation. Modified ha to 8 mm (δ = 14°), the neighboring wall jets developed nearly in the same direction, diminishing the interferential capacity. Similar higher-temperature and higher-soot areas were observed during the burn-out process for ha = 2 and 8 mm compared to what was obtained at ha = 6 mm, except that the bright area of ha = 2 mm was located near the convex edge at the bottom, while ha = 8 mm appeared in a higher position. Therefore, the LSCS, through exerting the comprehensive effects of wall-flow-guided and interferential interactions, obtains the optimal fuel/air mixing and combustion effects.

On Optimal Embeddings in 3-Ary n-Cubes

The efficiency of a graph embedding problem when simulating one interconnection network in another interconnection network is characterized by the influential parameter of wirelength. Obtaining the minimum wirelength in an embedding problem determines the quality of that embedding. In this paper, we obtained the convex edge partition of 3-Ary n-Cubes and the minimized wirelength of the embeddings of both 3-Ary n-Cubes and circulant networks.

Placement of working bodies on the frame of the tool plow-ripper

The purpose is to investigate substantiate relative position working bodies of improved plow-ripper. Scheme of the plow-ripper is given. The plow-ripper consists of the left and right sections, a ripping share established down the axle of symmetry tool, improved working bodies with inclined racks. Analytics dependencies are mined to define distance between working organs and the distance between them along the plow-ripper. Experiments have been carried out come true the relation stance working bodywork. Experiments have established that with an increase in the distance between the working bodies with an inclined stand along the plow, the hail of crumbling ground increasing accordance law of a convex edge and the pulling force in accordance law of a curved parabola. It has been determined that in order to ensure the reliability of work and the quality of tillage with a minimum traction resistance, the spacing should be at least 30 cm, and the distance between the working bodies along the plow-ripper should be 60 cm.

The effects of planform morphology on two-dimensional wave transformation over near-horizontal shore platforms

Shore platforms fronting cliffs have highly irregular planform configurations that could modify the alongshore distribution of wave energy, thereby influencing cliff erosion. However, research aiming to understand the geomorphological control of platform morphology on two-dimensional wave transformation remains scarce. We conducted detailed wave measurements within the intertidal zone of three commonly observed mesoscale planform geometries (straight, concave and convex seaward edges). Waves were measured using a phased array of pressure transducers near the seaward edge of three near-horizontal shore platforms in New Zealand. Waves were analysed at infragravity (IG: 0.002–0.05 Hz) and swell frequencies (SW: 0.05–0.125 Hz), with wave energy derived from the zeroth moment wave height, directional wave spectra derived from the Extension of the Maximum Entropy Method and phase lag derived from the cross-spectrum characteristics. Results showed that wave translation occurred on the straight edge platform, divergence on the concave platform, and convergence on the convex platform. These patterns generated areas of wave ray convergence and divergence over the platforms. Wave energy convergence coincided with increased IG energy and reduced SW energy decay, whereas divergence had the opposite effects. Wave reflection generated cross-shore standing IG waves, for which nodal states varied alongshore with platform width. These phenomena resulted in alongshore variations in normalised wave energy Ê over the three platforms, which were more pronounced for IG than for SW. Compared to the straight platform, alongshore variations of IG were twice as large on the concave platform and three times larger on the convex platform. This study shows that planform morphology impacts along-platform wave energy distribution. These effects likely influence planform rock coast evolution and should be considered in future numerical modelling studies.

All-round: combining laser cutting and edge shaping of glass

Cutting glass to shape with ultra short laser pulses is nowadays a well established industrial process. Pulses with an elongated straight focal volume (line focus) are used to modify the workpiece throughout its entire depth with one single laser shot. At the same time, processed glass is often required to have a seamed or round edge, which usually requires an extra grinding step. Here we demonstrate that curved line foci can be used to combine cutting and edge shaping of glass sheets in one laser process. We reconsider the Airy-Gauss beam for this purpose, and suggest modifications to the beam profile to avoid unwanted effects, in particular an asymmetric laser modification of the glass sheet. We provide a combined experimental and numerical analysis of the laser process, and show a symmetric convex edge created in a \({920}\,{\upmu }\mathrm{m}\) thick glass sheet.

Numerical analysis of mixing and combustion characteristics of a lateral swirl combustion system in OP2S diesel engines

Opposed-Piston, Two-Stroke (OP2S) diesel engine is a potential powertrain to achieve efficient and clean combustion. However, its non-uniformity of mixing and combustion restricts performance improvement. To solve this problem, this work proposed a lateral swirl combustion system (LSCS) for the OP2S diesel engine. Applying CFD simulation, this work studied the effects of different combustion chamber parameters on the mixing and combustion performance, power, and emissions of the LSCS of the OP2S diesel engine. Furthermore, the combustion parameters were optimized by sensitivity analysis and parameter normalization methods. The results show that the LSCS helps improve the non-uniformity of mixing &amp; combustion of the OP2S diesel engine, accelerate burning, improve the power of the OP2S diesel engine and reduce soot emissions. Besides, under certain fuel supply conditions, it is necessary to make good use of the space of the axial and radial sections of the combustion chamber and make the convex edge height realize the split-flow effect. Therefore the performance of the LSCS can be improved effectively in the OP2S diesel engine.

A calculation method of phenotypic traits of soybean pods based on image processing technology

As a homologous organ of the leaf, the pod is an essential factor in determining the yield and quality of the grain. The physiological and ecological characteristics of pods are a critical basis for soybean breeding and yield estimation. In order to avoid time-consuming and laborious problems in the traditional manual measurement process, a fast calculation method of pod's phenotypic traits was proposed based on image processing technology. First, two varieties (Heihe 49 and Suinong 26) were taken as the research objects. The self-developed image acquisition platform was used to obtain the color images of soybean pods at different growth stages. Second, the geometric distortion of the raw image was registered by using the linear mapping equation. In addition, the edge of the pod was extracted by the Gaussian filter function and Canny detection operator. Finally, the length, width, and area of pods were calculated based on the minimum circumscribed rectangle method, the maximum inscribed circle method, and the pixel count of pod's contour area combined with the template calibration method. The shape and the number of seeds were calculated based on the interval duty cycle method, the interval duty cycle combined with the arc length of pod's convex edge. The results showed that the accuracy between the calculated values and the standard values of pod length, pod width, pod area, pod shape, and the number of seeds was 97.8%, 95.1%, 97.1%, 93.2%, and 85%, respectively. Thus, the proposed method can provide not only a rapid detection for quantitative indexes of soybean seed test and yield estimation, but also a theoretical basis and technical knowledge for soybean breeding and scientific cultivation.

Research on surface microstructures and properties of NiTi shape memory alloy after wire electrical discharge machining

This paper used wire electrical discharge machining (WEDM) to machine Nickel-titanium shape memory alloy (NiTi-SMA). Since NiTi-SMA is very sensitive to temperature, the surface of WEDM will form an altered-metal zone (AMZ), which affects the material performance. For investigating the effects of WEDM on the surface microstructures and properties, the method of experimenting clarified the thermal damage mechanism of NiTi-SAM surface formed by WEDM. After WEDM, an obvious three-layer structure (spattered layer, recast layer, and heat-affected layer) was formed on the machined surface, the grains in the recast layer were refined, and the microhardness of the recast layer was significantly improved, the formed hardened layer inhibits the deformation recovery of NiTi-SAM. For machining defects, multi-cutting methods are used to reduce the impact on the machining of NiTi-SAM. Results show that increasing the cutting passes reduces the size of craters and hard convex edges, producing a smoother surface, the roughness Ra value was reduced from 2.79 µm to 0.12 µm. After main cutting, the spattered and recast layers' thickness reached 18.16 µm, and many microcracks appeared in the AMZ. After the fifth trimming, the thickness of the recast layer gradually decreased to less than 0.3 µm. Due to the excellent surface state and enough thinned recast layer, the sample exhibited good corrosion resistance and shape recovery capability. Experimental results provide a reliable processing method for applying NiTi-SMA in micro-electro-mechanical systems and biomedical fields.

All carbon p-n border in bilayer graphene by the molecular orientation of intercalated corannulene

Geometric and electronic structures of a corannulene (C20H10) intercalated bilayer graphene are investigated in terms of the molecular conformation using density functional theory. Our calculations indicate that the electronic structure of bilayer graphene is tunable by controlling the molecular conformation of corannulene. Holes and electrons coexist on the upper and lower layers of graphene, which are situated at the convex region and edge of corannulene when it has the bowl conformation. In contrast, bilayer graphene has a tiny gap of 4.7 meV at the K point owing to the substantial interaction between graphene and corannulene when corannulene has flat conformation. Electron and hole redistribution in bilayer graphene intercalating corannulene indicated the possibility of all carbon p-n border at an interface between corannulene with convex and concave arrangements. The intercalation substantially decreases the energy difference between the ground state bowl conformation and the metastable state flat conformation by approximately 400 meV. Accordingly, the two-dimensional nano-spacing between the graphene layers changes the molecular conformation of corannulene from a bowl to a flat structure at 139 MPa.

Effect of Needle Type, Number of Layers on FPAFC Composite against Low-Velocity Projectile Impact

Protective structures subjected to intensive loads that may benefit from the use of multilayer composite structures with excellent hardness and impact resistance represent an emerging research field in recent times. In this study, low-velocity projectile impact tests were performed on Functionally-graded Preplaced Aggregate Fibrous Concrete (FPAFC) mixtures to evaluate their performance. The effects of projectile needle type, fibre type and hybridization in addition to the number of layers in the composites on projectile impact were investigated. The bioinspiration of the excellent impact strength of turtle shells was used to design an FPAFC comprising a higher amount of steel and polypropylene fibres at the outer layers. In parallel, one and two-layered concretes were also cast to assess the effectiveness of three-layered FPAFC. The tests were performed on disc specimens using non-deformable compound bevel, convex edge and hollow edge projectiles. The damage severity was quantified by the top damage area, bottom damage area and depth of penetration. In addition, a simple analytical model for predicting the composite mass expulsion was developed and implemented. Findings indicated that regardless of fiber type and distribution, the compound bevel projectile needle produced the lowest impact numbers for all single, double and triple-layer specimens compared to the convex edge and hollow edge projectiles. Repeated projectile impacts increased the penetration depth and damaged area at the top and bottom surfaces of all targets. Targets were more resistant to convex edge and hollow edge projectile penetration than the compound bevel. The experimental and analytical model results for mass expelled from the top surface are reasonably acceptable. This research gives an idea of developing advanced fibrous composite with superior impact resistance for the promising protective structures.

Shaping convex edges in borosilicate glass by single pass perforation with an Airy beam.

We demonstrate curved modifications with lengths of up to 2 mm within borosilicate glass produced by single 1030 nm picosecond laser shots with an Airy beam profile. Plasma ignition in the sidelobes of the beam as well as surface damage prove to be the crucial limitations for confined bulk energy deposition on a curved trajectory. A combined experimental and numerical analysis reveals optimum laser parameters for confined bulk energy deposition. This way, we achieved single pass perforation of a 525 µm thick glass sheet and separation by a subsequent etching step, resulting in a well-defined convex edge down to a radius of curvature of 774 µm.