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Abstract Since the discovery of graphene and its remarkable properties, researchers have actively explored advanced graphene-patterning technologies. While the etching process is pivotal in shaping graphene channels, existing etching techniques have limitations such as low speed, high cost, residue contamination, and rough edges. Therefore, the development of facile and efficient etching methods is necessary. This study entailed the development of a novel technique for patterning graphene through dry etching, utilizing selective photochemical reactions precisely targeted at single-layer graphene (SLG) surfaces. This process is facilitated by an excimer ultraviolet lamp emitting light at a wavelength of 172 nm. The effectiveness of this technique in selectively removing SLG over large areas, leaving the few-layer graphene intact and clean, was confirmed by various spectroscopic analyses. Furthermore, we explored the application of this technique to device fabrication, revealing its potential to enhance the electrical properties of SLG-based devices. One-dimensional (1D) edge contacts fabricated using this method not only exhibited enhanced electrical transport characteristics compared to two-dimensional contact devices but also demonstrated enhanced efficiency in fabricating conventional 1D-contacted devices. This study addresses the demand for advanced technologies suitable for next-generation graphene devices, providing a promising and versatile graphene-patterning approach with broad applicability and high efficiency.

Since the discovery of graphene and its remarkable properties, researchers have actively explored advanced graphene-patterning technologies. While the etching process is pivotal in shaping graphene channels, existing etching techniques have limitations such as low speed, high cost, residue contamination, and rough edges. Therefore, the development of facile and efficient etching methods is necessary. This study entailed the development of a novel technique for patterning graphene through dry etching, utilizing selective photochemical reactions precisely targeted at single-layer graphene (SLG) surfaces. This process is facilitated by an excimer ultraviolet lamp emitting light at a wavelength of 172 nm. The effectiveness of this technique in selectively removing SLG over large areas, leaving the few-layer graphene intact and clean, was confirmed by various spectroscopic analyses. Furthermore, we explored the application of this technique to device fabrication, revealing its potential to enhance the electrical properties of SLG-based devices. One-dimensional (1D) edge contacts fabricated using this method not only exhibited enhanced electrical transport characteristics compared to two-dimensional contact devices but also demonstrated enhanced efficiency in fabricating conventional 1D-contacted devices. This study addresses the demand for advanced technologies suitable for next-generation graphene devices, providing a promising and versatile graphene-patterning approach with broad applicability and high efficiency. This study introduces a novel selective etching method for single-layer graphene (SLG) using excimer UV irradiation under ambient conditions. Its high selectivity enables the precise removal of SLG, while leaving other graphene-based structures intact. Using this technique, we effectively fabricated edge-contact devices via SLG patterning with hBN masks. This advancement holds significant promise for expanding the applicability of graphene and paving the way for large-area applications. [ABSTRACT FROM AUTHOR]

Accurately and fast calculation of single tooth load contact state of a gear pair is the basis for accurate calculation of multi-tooth load contact analysis. Therefore, this study proposed a semi-analytical quick single tooth load tooth contact analysis (Q-SLTCA) method. First, the ease-off tooth contact analysis (ease-off TCA) method was established, and a numerically stable initial contact stress distribution and contact ellipse analytical model was derived. Then, considering the influence of edge contact, the real-time division method of gear tooth slice was derived. Based on this, the equivalent principle of contact elliptical node and the load correction strategy were innovatively proposed. Then, the calculation method of the meshing characteristics of the tooth slice was established by coupling the boundary element method (BEM) with the equivalent cylindrical Hertz contact theory. The bending deformation, tooth root stress distribution, contact stress, contact deformation and meshing stiffness of the tooth slice were analyzed and calculated, and the instantaneous meshing stiffness of the single tooth was determined by combining the parallel method of the gear tooth stiffness. Finally, a single-tooth finite element method (FEM) meshing model was created for comparison with the method in this study, which verified the calculation accuracy and efficiency of the proposed method. This method can be easily developed into a quick multi-tooth load contact analysis algorithm, which can provide a new method for gear tooth crack and failure analysis. • Propose a real-time division method of tooth slice combined with ease-off TCA. • Propose an elliptical node equivalent principle and load correction strategy considering edge contact. • Derive the BEM equation for calculating the mechanical properties of the tooth slice. • Use BEM and Hertz theory to conduct load tooth surface contact analysis. [ABSTRACT FROM AUTHOR]

The article deals with the issues of modeling the stress-strain state of the attachment points of the cab of a wheeled chassis of high load capacity. The main design loads are determined. Geometric and computational finite element models are constructed, taking into account the features of the metal structure. The technique of gluing elements of the grid model is applied. The contact interaction of the parts is taken into account. Based on the calculations performed, conclusions are drawn about the compliance of the developed structure with the strength requirements.

Contact resistance strongly deteriorates the performance of devices based on 2-D materials and their nanostructures, masking their exceptional electronic and transport properties. This work explores the dependence of contact resistance (${R}_{C}$) of graphene nanoribbon (GNR) devices on contact geometry using atomistic quantum transport simulations. The influence and contributions of edge and top contacts and GNR width scaling on ${R}_{C}$ is studied in detail. Metallization effects on the density of states, transmission, and GNR field-effect transistor (GNR FET) driving current are investigated. We show that wider GNRs (~4 nm) exhibit edge-dominated transport and lower ${R}_{C}$ than the ultranarrow GNRs (~0.4 nm) that exhibit much higher contact resistance which is also dependent on the contact area. [ABSTRACT FROM AUTHOR]

Optimization with edge contact avoidance and contact stress minimization is essential for gear design. Due to the complex geometry of modified helical face gear drives, it is complicated to find the optimal design parameters with the consideration of issues including loading, assembly errors, and edge contact. As the finite element method is tedious and time-consuming, an optimization model with a simplified algorithm of the loaded tooth contact analysis with errors (ELTCA) for modified helical face gears is presented, and it can programmatically optimize the contact stress with edge contact avoidance. Firstly, a simplified ETCA algorithm is introduced, which reduces the five unknowns in the traditional contact equations to three. Secondly, the LTCA is analytically implemented according to the Hertz theory. Subsequently, an optimization model with the objective function of avoiding edge contact and reducing maximum contact stress is proposed. Furthermore, the proposed model is applied to reveal the effects of design parameters and assembly errors on the optimized contact path and stress. The results show that the optimization model is accurate and efficient; the design parameters and assembly errors have great effects on the meshing of modified helical face gears. [ABSTRACT FROM AUTHOR]

This study explores the inhomogeneity problem near the edge of a cantilever beam. Common in gears and turbine blades, inhomogeneities under local edge contact, coupled with macroscale bending effects, result in extreme and complex stress concentration. This model employs the Conjugate Gradient Method to combines the macroscopic beam theory and microscopic elasticity. The Eshelby inclusion method for simulating inhomogeneities. The Hetényi image method is used for address edge contacts in the beam. Enhanced by the Discrete Convolution fast Fourier Transform algorithm, the model's accuracy and efficiency are validated with the Finite element method. Parametric analysis highlights the influence of distance between indenter and edge, stress components distribution and potential failure in cross-scale challenges. [Display omitted] • New model for inhomogeneous beam indentation introduced. • Novel micro-macro beam-indentation approach using Conjugate Gradient Method. • Model includes edge contact with Hetényi method and Equivalent inclusion method. • Model gains accuracy with fast Fourier transform and Conjugate Gradient Method. [ABSTRACT FROM AUTHOR]

A great challenge is presented when metals have contact with a 2D semiconducting material because the contact resistances (Rc) induced at the metal‐graphene interfaces hinder the performances of 2D devices, and therefore low resistance Ohmic contacts need to be developed to achieve unique and high performance of the 2D devices. This study demonstrates that edge‐contacted graphene devices of multiple stacked 2D hetero‐structures with hexagonal boron nitride (hBN) exhibit superior performances in carrier transport across channel and contact regions, compared to surface‐contacted devices. In surface‐contacted graphene devices, Rc and contact resistivity (ρc) are calculated by applying the modified transfer length (LT*) obtained from the contact‐end‐resistance method, while Rc and ρc in edge‐contacted graphene devices are estimated by replacing the LT* with the thickness of graphene. The edge‐contacted device is fabricated via a controlled plasma etching that allows each layer of graphene and hBN consisting hetero‐structures to be removed evenly at a uniform speed. Four‐point probe measurements are conducted in addition to transmission line method and confirms that ρc is lower for edge contact than surface contact. ρc of a graphene edge‐contacted device (≈10 Ω µm2) is much lower than that of a surface‐contacted device (≈230 Ω µm2). [ABSTRACT FROM AUTHOR]

Edge contacts are promising for improving carrier injection and contact resistance in devices based on two-dimensional (2D) materials, among which monolayer black phosphorus (BP), or phosphorene, is especially attractive for device applications. Cutting BP into phosphorene nanoribbons (PNRs) widens the design space for BP devices and enables high-density device integration. However, little is known about contact resistance (RC) in PNRs with edge contacts, although RC is the main performance limiter for 2D material devices. Atomistic quantum transport simulations are employed to explore the impact of attaching metal edge contacts (MECs) on the electronic and transport properties and contact resistance of PNRs. We demonstrate that PNR length downscaling increases RC to 192 Ω µm in 5.2 nm-long PNRs due to strong metallization effects, while width downscaling decreases the RC to 19 Ω µm in 0.5 nm-wide PNRs. These findings illustrate the limitations on PNR downscaling and reveal opportunities in the minimization of RC by device sizing. Moreover, we prove the existence of optimum metals for edge contacts in terms of minimum metallization effects that further decrease RC by ~30%, resulting in lower intrinsic quantum limits to RC of ~90 Ω µm in phosphorene and ~14 Ω µm in ultra-narrow PNRs. [ABSTRACT FROM AUTHOR]

To avoid edge contact and stress concentration on the tooth surface of hypoid gear pairs machined by the duplex helical method for the drive axle of heavy-duty vehicles, a four-segment tool profile was designed for the simultaneous modification of the concave and convex surfaces of the pinion. First, a geometric model of the four-segment tool profile was established. Second, a mathematical model of the duplex helical method based on the four-segment tool profile was established, and a method for solving the tooth surface generated by the connecting points of the four-segment tool profile was presented. Finally, loaded tooth contact analysis based on finite element method was used to analyse the meshing performance of the gear pair obtained by the four-segment tool profile modification. The results of the original and modified gear pairs were compared. The tooth surface modification inhibited edge contact, improved the stress distribution, and decreased the maximum contact stress of the tooth surfaces, thereby improving the fatigue and wear life of the gear pair. [ABSTRACT FROM AUTHOR]

Highly anisotropic black phosphorus (BP) has recently attracted significant interest for electronic and optoelectronic devices. To date, in‐plane anisotropic properties of BP field effect transistors (FETs) have been reported only with top contact. However, the 2D top contact geometry is unable to measure the in‐plane electrical conductance precisely, due to the presence of the out‐of‐plane conductance, resulting in underestimation of anisotropy. Here, 1D edge contact method is employed to measure the in‐plane conductance precisely along the armchair and zigzag directions of BP without the contribution of out‐of‐plane conductance. The conductance and mobility anisotropies for BP FETs are measured with edge contact at 300 K to be ≈5.5 and ≈7.5, respectively. The results further show that the mobility of BP FETs with edge contact weakly depends on temperature, indicating that the edge roughness scattering limits the mobility. In contrast, the mobility of BP FETs with top contact strongly depends on temperature, showing that the impurity scattering and phonon scattering limit the mobility at below and above 150 K, respectively. Finally, a scattering phase diagram is demonstrated to understand the role of different scattering mechanisms on the modulation of mobility anisotropy in BP FETs with edge and top contacts. [ABSTRACT FROM AUTHOR]

The tooth surface grid node coordinates are accurately calculated by the tooth surface equation. According to the density requirements of the grid nodes， the grid nodes are evenly divided， the tooth root transition curve mesh is encrypted， and the finite element software is directly imported to generate an accurate finite element model of the spiral bevel gear meshing transmission. Tooth surfaces with different geometric transmission errors are designed， and the loaded tooth contact analysis is performed by using finite element software，and the contact stress and loaded transmission error of gear pairs with different geometric transmission errors are analyzed. Based on the modal superposition method， the vibration response analysis of the spiral bevel gear is used to obtain the vibration displacement， velocity， acceleration. The comparison results show that under the load of 200 N·m， as the geometric transmission error increases， the degree of edge contact decreases， the fluctuation of the upper and lower amplitudes of the loaded transmission error decreases by 44%， and the corresponding vibration displacement， speed and acceleration decrease， effectively reduce deformation and vibration.

The persistent challenges encountered in metal-transition-metal dichalcogenide (TMD) junctions, including tunneling barriers and Fermi-level pinning, pose significant impediments to achieving optimal charge transport and reducing contact resistance. To address these challenges, a pioneering self-aligned edge contact (SAEC) process tailored for TMD-based field-effect transistors (FETs) is developed by integrating a WS 2 semiconductor with a hexagonal boron nitride dielectric via reactive ion etching. This approach streamlines semiconductor fabrication by enabling edge contact formation without the need for additional lithography steps. Notably, SAEC TMD-based FETs exhibit exceptional device performance, featuring a high on/off current ratio of ∼10 8 , field-effect mobility of up to 120 cm 2 /V·s, and controllable polarity─essential attributes for advanced TMD-based logic circuits. Furthermore, the SAEC process enables precise electrode positioning and effective minimization of parasitic capacitance, which are pivotal for attaining high-speed characteristics in TMD-based electronics. The compatibility of the SAEC technique with existing Si self-aligned processes underscores its feasibility for integration into post-CMOS applications, heralding an upcoming era of integration of TMDs into Si semiconductor electronics. The introduction of the SAEC process represents a significant advancement in TMD-based microelectronics and is poised to unlock the full potential of TMDs for future electronic technologies.

Electronic devices employing two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenide (TMD) layers as semiconducting channels often exhibit limited performance (e.g., low carrier mobility), in part, due to their high contact resistances caused by interfacing non-vdW three-dimensional (3D) metal electrodes. Herein, we report that this intrinsic contact issue can be efficiently mitigated by forming the 2D/2D in-plane junctions of 2D semiconductor channels seamlessly interfaced with 2D metal electrodes. For this, we demonstrated the selectively patterned conversion of semiconducting 2D PtSe 2 (channels) to metallic 2D PtTe 2 (electrodes) layers by employing a wafer-scale low-temperature chemical vapor deposition (CVD) process. We investigated a variety of field-effect transistors (FETs) employing wafer-scale CVD-2D PtSe 2 /2D PtTe 2 heterolayers and identified that silicon dioxide (SiO 2 ) top-gated FETs exhibited an extremely high hole mobility of ∼120 cm 2 V -1 s -1 at room temperature, significantly surpassing performances with previous wafer-scale 2D PtSe 2 -based FETs. The low-temperature nature of the CVD method further allowed for the direct fabrication of wafer-scale arrays of 2D PtSe 2 /2D PtTe 2 heterolayers on polyamide (PI) substrates, which intrinsically displayed optical pulse-induced artificial synaptic behaviors. This study is believed to vastly broaden the applicability of 2D TMD layers for next-generation, high-performance electronic devices with unconventional functionalities.

We use atomistic quantum transport device simulations to investigate the contact resistance (${R}_{C}$) in monoelemental 2D material nanoribbon MOSFETs with edge contacts. The consequences of attaching metal electrodes to source/drain regions are investigated for various metal-channel interaction strengths and nanoribbon dimensions. We find that ${R}_{C}$ is minimized by using moderately interacting metallic materials, and that the minimum ${R}_{C}$ is $\sim 150~\Omega \cdot \mu \text{m}$ in graphene, silicene and germanene, and $\sim 430~\Omega \cdot \mu \text{m}$ in phosphorene nanodevices with edge contacts. [ABSTRACT FROM AUTHOR]

Optimization with edge contact avoidance and contact stress minimization is essential for gear design. Due to the complex geometry of modified helical face gear drives, it is complicated to find the optimal design parameters with the consideration of issues including loading, assembly errors, and edge contact. As the finite element method is tedious and time-consuming, an optimization model with a simplified algorithm of the loaded tooth contact analysis with errors (ELTCA) for modified helical face gears is presented, and it can programmatically optimize the contact stress with edge contact avoidance. Firstly, a simplified ETCA algorithm is introduced, which reduces the five unknowns in the traditional contact equations to three. Secondly, the LTCA is analytically implemented according to the Hertz theory. Subsequently, an optimization model with the objective function of avoiding edge contact and reducing maximum contact stress is proposed. Furthermore, the proposed model is applied to reveal the effects of design parameters and assembly errors on the optimized contact path and stress. The results show that the optimization model is accurate and efficient; the design parameters and assembly errors have great effects on the meshing of modified helical face gears.

Improving gear mesh efficiency contributes to reducing the environmental impact of vehicles. This study examined the effect of adjusting gear specifications on improving mesh efficiency. When the gear ratio of cylindrical gears is relatively high, it tends to increase the sliding velocity between the engaging gear teeth. Moving the contact region toward the base circle of the pinion along the line of action is considered to be one solution for reducing friction loss. However, it may cause deterioration of tooth surface strength because the radius of curvature of the tooth surface becomes smaller on account of being closer to the base circle. In order to confirm the influence of the gear meshing region on tooth surface strength, gear durability tests were carried out and tooth damage states were observed in detail under a microscope. The results revealed that pitting failure occurred near the tooth root region of the pinion. Furthermore, trochoidal interference due to the high torque condition extended over the base circle. In this case, trochoidal interference has a greater influence on pitting failure. In order to investigate the effect of reducing trochoidal interference near the base circle on pitting failure, further gear durability tests were conducted using the mating gears with large tooth tip modification. However, the effect on improving pitting durability was limited. Multidirectional, interacting wear was observed not only in the profile direction due to trochoidal interference but also in the lead direction due to edge contact. Such wear changed the location of pits. The results of these detailed investigation revealed a new viewpoint for explaining the mechanism of these phenomena in terms of conflict between pitting and multidirectional, interacting wear. Presumably, pitting failure changes if the state of progression of trochoidal interference and wear in the lead direction changes. In order to confirm the influence of such wear on pitting durability, a gear durability test was conducted using gears with tooth tip modification and endface relief. The test results confirmed that the location of pits and pitting durability changed. These results revealed that pitting durability and the state of damage were influenced sensitively and compositely by multidirectional, interacting wear, i.e., wear in the profile and lead directions.

Edge contacts are promising for improving carrier injection and contact resistance in devices based on two-dimensional (2D) materials, among which monolayer black phosphorus (BP), or phosphorene, is especially attractive for device applications. Cutting BP into phosphorene nanoribbons (PNRs) widens the design space for BP devices and enables high-density device integration. However, little is known about contact resistance (RC) in PNRs with edge contacts, although RC is the main performance limiter for 2D material devices. Atomistic quantum transport simulations are employed to explore the impact of attaching metal edge contacts (MECs) on the electronic and transport properties and contact resistance of PNRs. We demonstrate that PNR length downscaling increases RC to 192 Ω µm in 5.2 nm-long PNRs due to strong metallization effects, while width downscaling decreases the RC to 19 Ω µm in 0.5 nm-wide PNRs. These findings illustrate the limitations on PNR downscaling and reveal opportunities in the minimization of RC by device sizing. Moreover, we prove the existence of optimum metals for edge contacts in terms of minimum metallization effects that further decrease RC by ~30%, resulting in lower intrinsic quantum limits to RC of ~90 Ω µm in phosphorene and ~14 Ω µm in ultra-narrow PNRs.

In order to explore the contact mechanical properties of artificial hip joint under different materials and structural parameters,a finite element model of the ball based common hip joint is established by using the finite element method. The contact mechanical properties of the acetabulum cup under different material combinations and structural parameters are analyzed by applying a vertical upward load on the center of the femoral head. The results show that with the increase of the elastic modulus of the material, the contact pressure between the mating pairs increases, the corresponding contact area decreases, and the change trend of the contact pressure of the mating pairs of different materials under the same structural parameters is basically the same; in the structural parameters, the clearance between the femoral head and the cup, the diameter of the femoral head have the greatest influence on the contact pressure, and the edge contact phenomenon will occur when the angle of the cup exceeds 60°. The research results can be used as a reference for the design and installation of artificial hip joints. [ABSTRACT FROM AUTHOR]

To avoid the occurrence of the hub tooth tip edge contact with the sleeve tooth root flank and the sleeve tooth tip edge contact with the hub tooth root flank, a novel crown gear coupling composed of a hub with profile crowning, longitude crowning, and tip sphere teeth, and a sleeve with straight internal teeth is presented in this paper. The generating procedure of the hub with profile parabolic modification for the novel crown gear coupling is proposed. And the meshing model with angular misalignment of the novel crown gear coupling is developed. Tooth contact analysis (TCA) based on the theory of gearing and loaded tooth contact analysis (LTCA) based on finite element method (FEM) are employed to simulate contact path and to calculate contact stress distributions of the novel crown gear coupling. An example crown gear coupling is presented. The effects of profile parabolic modification coefficient and misalignment angle on contact path are investigated both for the conventional and novel crown gear couplings. Also, contact stress distributions are analyzed both for them with the maximum misalignment angle. The performed research proves that an appropriate amount of profile modification for the hub of the crown gear coupling permits the avoidance of edge contact in presence of angular misalignment, and can significantly reduce the maximum contact stress, compared with the conventional one.

Two-dimensional (2D) transition metal dichalcogenide (TMD) layers are highly promising as field-effect transistor (FET) channels in the atomic-scale limit. However, accomplishing this superiority in scaled-up FETs remains challenging due to their van der Waals (vdW) bonding nature with respect to conventional metal electrodes. Herein, we report a scalable approach to fabricate centimeter-scale all-2D FET arrays of platinum diselenide (PtSe 2 ) with in-plane platinum ditelluride (PtTe 2 ) edge contacts, mitigating the aforementioned challenges. We realized a reversible transition between semiconducting PtSe 2 and metallic PtTe 2 via a low-temperature anion exchange reaction compatible with the back-end-of-line (BEOL) processes. All-2D PtSe 2 FETs seamlessly edge-contacted with transited metallic PtTe 2 exhibited significant performance improvements compared to those with surface-contacted gold electrodes, e.g., an increase of carrier mobility and on/off ratio by over an order of magnitude, achieving a maximum hole mobility of ∼50.30 cm 2 V -1 s -1 at room temperature. This study opens up new opportunities toward atomically thin 2D-TMD-based circuitries with extraordinary functionalities.

van der Waals heterostructures (vdWHs) based on two-dimensional (2D) semiconductors have attracted considerable attention. However, the reported vdWHs are largely based on vertical device structure with large overlapping area, while the realization of lateral heterostructures contacted through 2D edges remains challenging and is majorly limited by the difficulties of manipulating the lateral distance of 2D materials at nanometer scale (during transfer process). Here, we demonstrate a simple interfacial sliding approach for realizing an edge-by-edge lateral contact. By stretching a vertical vdWH, two 2D flakes could gradually slide apart or toward each other. Therefore, by applying proper strain, the initial vertical vdWH could be converted into a lateral heterojunction with intimately contacted 2D edges. The lateral contact structure is supported by both microscope characterization and in situ electrical measurements, exhibiting carrier tunneling behavior. Finally, this approach can be extended to 3D thin films, as demonstrated by the lateral 2D/3D and 3D/3D Schottky junction.

• Generation of the backlash-adjustable face-gear drive including a tapered involute pinion is performed. • The limiting conditions of the tapered involute pinion and the face-gear are investigated. • The double crowned tapered involute pinion is proposed by application of a generating worm. • TCA and stress analysis are implemented. The face-gear drive with a double-crowned pinion performs better. • The backlash of the face-gear drive can be adjusted through the axial movement of the pinion and little influence occurred. This paper focuses on the face-gear drive with a tapered involute pinion. Two types of pinion geometries are derived: 1) the profile crowned pinion implemented by a crowned rack-cutter, and 2) the double-crowned pinion by a generating worm. The tooth surfaces and the limiting conditions of the pinion and the face-gear are obtained based on the meshing and geometry theories. The tooth contact analysis (TCA) and stress analysis are performed to evaluate the performance of the presented face-gear drive. The results indicate that the backlash adjusting of the face-gear drive can be achieved by axially moving the pinion. The application of double-crowned pinion modifies the contact patterns on the gear surfaces, providing lower contact and bending stresses compared with the face-gear drive using a profile crowned pinion. Both the profile crowned and double-crowned pinions can relieve the edge contact effects. Numerical examples are given to illustrate the results. [ABSTRACT FROM AUTHOR]

This paper considers the wear process of the teeth of straight spur gear transmissions under the conditions of skew of the axes of conjugated wheels. The method for determining the magnitude of wear of tooth profiles, taking the skew angle into account, is based on the dependence of average contact pressure on the skew angle. To determine the contact pressure, the physical and mathematical model of contact interaction of cylindrical elastic bodies is used when they are skewed using the Winkler model of elastic foundation. It is established that the presence of skew angle of teeth of 0.1° increases the wear rate by 3.61 times. [ABSTRACT FROM AUTHOR]

Abstract First principles calculations are carried out to study the effect of contact configurations on the electronic and transport properties of borophane-MoSe 2 heterojunction. Four different contact configurations between borophane and MoSe 2 are designed and the most stable configurations are determined. Calculations show that metallic behavior is appeared in semiconductor MoSe 2 as a result of junction formation with borophane. The metallic states are mainly located at the contact interface and produced by d states of Mo atoms, p states of B and Se atoms. The calculated band alignments indicate that n -type Schottky contacts are formed between borophane and MoSe 2. The different current-voltage behaviors of two represented configurations indicate the contact configurations are important for the electronic transport properties of borophane-MoSe 2 heterojunction. Highlights • Four different contact edges between borophane and MoSe 2 are constructed. • MoSe 2 is metalized as a consequence of junction formation with borophane. • n-type Schottky contacts are found in four borophane-MoSe 2 lateral heterostructures. • The electronic and transport properties rely on the contact geometries of borophane-MoSe 2 heterostructures. [ABSTRACT FROM AUTHOR]

The present paper describes edge contact analyses for power transmission gears using tooth-flank-film elements, which have been proposed for finite element analyses of tooth stresses. For edge contact analyses, the tooth-flank-film elements are placed not only on usable flanks but also over tooth edges. Finer elements on edge neighboring areas and on the parts of usable tooth flanks where tend to contact with mating edges enable the edge contact to be analyzed. Comparisons of calculated distributions of tooth contact stress with observed tooth flanks after a running test showed the validity of the proposed method for edge contact analyses.

[Display omitted] • In-plane mixed-dimensional heterostructures of MoS 2 and Mo/Te were synthesized. • The composition, dimension and phase of heterostructures were controlled by Te flux. • In-plane 2D/2D/1D, 2D/1D and 2D/2D heterostructures were selectively fabricated. • The heterostructures exhibit Ohmic behavior between 2D semiconductor and 1D metal. • The synthesized heterostructures were used for low contact resistance optoelectronics. Mixed-dimensional heterostructures formed by combining 2D materials and other dimensional (0D, 1D, and 3D) materials provide new opportunities for various applications owing to their novel properties. However, in-plane mixed-dimensional heterostructures have been rarely investigated. Here, we report a novel flux-controlled chemical vapor deposition method for synthesizing in-plane mixed-dimensional heterostructures composed of monolayer MoS 2 and low-dimensional Mo/Te compounds. By adjusting the Te flux and growth time, we controlled the composition, dimension, and phase of the Mo/Te compounds interfaced with the MoS 2. While in-plane 2D/1D MoS 2 /Mo 6 Te 6 and 2D/2D/1D MoS 2 /2H MoTe 2 /Mo 6 Te 6 heterostructures were obtained with a low Te flux, in-plane 2D/2D MoS 2 /mixed 2H-1T' MoTe 2 and 2D/2D MoS 2 /2H MoTe 2 heterostructures were synthesized with a high Te flux. We investigated the transport properties of the devices fabricated with in-plane mixed-dimensional 2D/2D/1D MoS 2 /2H MoTe 2 /Mo 6 Te 6 heterostructures and imaged localized electronic band structures using scanning photocurrent microscopy. Under the low bias condition, the device exhibited an Ohmic-like behavior, which has not been achieved in conventional devices with stacked van der Waals junctions. Under the high bias condition, the device showed a rectifying behavior because of band-bending formed at the heterojunctions; this is consistent with the electronic band-alignment expected from the bandgap and electron affinity of the materials. [ABSTRACT FROM AUTHOR]

The vibrations of a double-seat weighty rotor of the steam turbine with a breathing transverse crack are examined in the field of operating environment temperatures. The 3D vibration model for the rotor with a breathing transverse crack is applied. The variable two-dimensional temperature field is found from the solution of nonstationary heat transfer problem. Its effect on the contact of crack edges on rotor vibrations was evaluated. The distribution of stress intensity factors along the crack front was established for different rotor positions. Fatigue crack extension modes are assessed. [ABSTRACT FROM AUTHOR]

A single enveloping worm gear of cylindrical worm gear drive is cut by an oversized hob. The oversize provides a longitudinal crowning on the worm gear tooth surface. However, when a lead angle of the worm becomes higher, the longitudinal crowning becomes more asymmetric. The asymmetrically crowned worm gear surface makes the gear contact more sensitive to the certain direction of misalignment. To change the longitudinal crowning from asymmetric to symmetric, a method of modified worm gear hobbing is proposed. The modification uses a modified machine tool setting and a modified hob specification. A new hobbing mechanism or hob geometry is not required in this method. Results of the proposed modification are confirmed by using a surface separation topology based on differential geometry, and contact pressure analysis based on finite element method. [ABSTRACT FROM AUTHOR]

Alumina ceramic total hip joint bearings have shown superior wear properties. The joint bearing may undergo adverse conditions such as micro-separation causing head contact on the cup rim. As a transition, an edge is formed between the cup bearing and the rim. The aim of this study was to predict the effect of the edge on contact stresses in order to better understand the mechanisms of wear. A finite element contact model was developed under the conditions of the head displacements 0.5–2 mm and vertical loads 0.5–3 kN. The edge contact produced the most severe stresses capable of causing elevated wear and damage to ceramic bearings. The study shows that the bearing design should be considered in association with clinical conditions to eliminate severe stress. [ABSTRACT FROM AUTHOR]

The electrical performance of graphene-based devices is largely limited by substantial contact resistance at the heterodimensional graphene-metal junctions. A laser-assisted nanowelding technique is developed to reduce graphene-metal (G-M) contact resistance and improve carrier injection in suspended graphene devices. Selective breakdown of CC bonds and formation of structural defects are realized through laser irradiation at the edges of graphene within the G-M contact regions in order to increase the chemical reactivity of graphene, facilitate G-M bonding, and, therefore, maximize interfacial carrier transportation. Through this method, significantly reduced G-M contact resistances, as low as 2.57 Ω µm are obtained. In addition, it is demonstrated that the location of laser-induced defects within the contact areas significantly impacts the interfacial properties and the carrier mobility of graphene devices. A fourfold increase in photocurrent is observed in the suspended graphene photodetectors with treated G-M interfaces as compared to ordinary ones. This contact-free and position-selective technique minimizes the degradation of the graphene channels and maintains the superior performance of graphene devices, making it a promising approach for reducing G-M resistance in the fabrication of graphene-based devices. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal dichalcogenides (TMDs) are promising materials for semiconductor nanodevices owing to their flexibility, transparency, and appropriate band gaps. A variety of optoelectronic and electronic devices based on TMDs p-n diodes have been extensively investigated due to their unique advantages. However, improving their performance is challenging for commercial applications. In this study, we propose a facile and doping-free approach based on the contact engineering of a few-layer tungsten di-selenide to form a lateral p-n homojunction photovoltaic. By combining surface and edge contacts for p-n diode fabrication, the photovoltaic effect is achieved with a high fill factor of ≈0.64, a power conversion efficiency of up to ≈4.5%, and the highest external quantum efficiency with a value of ≈67.6%. The photoresponsivity reaches 283 mA/W, indicating excellent photodiode performance. These results demonstrate that our technique has great potential for application in next-generation optoelectronic devices.

• An arbitrary contact point, whether or not edge contact, can be obtained. • The contact path, with or without edge contact, can be quickly obtained. • The approach is adapted for mismatched involute spiroid gears. The theoretical contact type of involute spiroid gears (IS) is line contact. The line contact will be turned out into point contact, even edge contact, due to errors. An improved algorithm for tooth contact analysis of mismatched IS is presented. The algorithm can be generally applied to the gears with point contact, whether edge contact occurs or not. Three methods are used in the algorithm: clearance method, edge rule and numerical method. Edge rule is provided to predict the contact type. The numerical method is used to solve nonlinear equations to obtain the precise contact point and contact path. The guess point can be estimated by the clearance method or the known contact point near the solution. In addition, the clearance method with high precision is utilized to avoid the invalidation of numerical method to ensure the robustness. Finally, the proposed algorithm is applied to simulating the meshing of helical gears and IS. The results are compared with those obtained by published literature or finite element method to verify the accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) has attracted a great deal of attention in optoelectronic applications due to its high mobility, low off-state current and high on/off ratio. However, its intrinsic large bandgap limits its application in infrared detection. Here, we have developed a high-performance infrared photodetector by integrating nonlayered PbS and layered MoS2 nanostructures via van der Waals epitaxy. Density functional theory (DFT) calculations indicate that PbS nanoplates are in contact with MoS2 edges through strong chemical hybridization, which is expected to offer a fast transmission path for carriers that enhances the response speed. The phototransistor exhibits a fast response (τrising = τdecay = 7.8 ms) as well as high photoresponsivity (4.5 × 104 A·W-1) and Ilight/Idark (1.3 × 10²) in the near-infrared spectral region at room temperature. In particular, the detectivity (D*) is as high as 3 × 1013 Jones, which is even better than that of commercial Si and InGaAs photodetectors. Furthermore, by controlling the growth and microfabrication patterning, periodic device arrays of PbS-MoS2 that are capable of infrared detection are achieved on Si/SiO2 substrates. Our work provides a possible method for the integration of photodetector arrays on Si-based electronic devices and lays a solid foundation for the practical applications of MoS2-based devices in the future. [ABSTRACT FROM AUTHOR]

This study examined the geometric interference of cylindrical worm gear drives using an oversized hob to cut the worm gear. The instantaneous line contact of a fully conjugated gear set becomes an instantaneous point contact when an oversized hob is used. In this type of worm gear drive, however, an edge contact can occur between the worm and worm gear. The edge contact is caused by geometric interference, and it occurs regardless of the presence of elastic deformation, misalignment, and transmission error. Aspects of the interference are presented through graphical illustrations. For examining the interference based on the differential geometry, two methods are proposed. The first method is for determining the surface separation topology between the tooth surfaces of a worm and a worm gear for an entire meshing cycle, and the second method for determining the boundary of the initially occurring area of interference when the hob oversize changes from zero to a nonzero value. By using the presented methods, the influence of various design parameters, such as the lead angle of the worm, the oversize of the hob, and the normal pressure angle, on the interference are examined and discussed through numerical examples. [ABSTRACT FROM AUTHOR]

We demonstrate a two-dimensional (2D) multilayered molybdenum disulfide (MoS2) transistor with molybdenum (Mo) side and edge contacts, which is deposited using a dc-sputtering method. It exhibits field-effect mobility of 23.9 cm ^\mathrm 2 /Vs and ON/OFF ratio of 10^\mathrm 6 in a linear region. A current–voltage study under different temperatures (300–393 K) reveals that the Mo–MoS2 transistor shows a band transport characteristics, and a Schottky barrier height of 0.14 eV is estimated using a thermionic emission theory. Finally, the side and edge contacts of Mo–MoS2 are confirmed through the transmission electron microscope analysis. Our results not only show that Mo can be an alternative contact metal to other low work-function metals but also that the edge contact may play an important role in resolving the performance degradation over thickness increase of the MoS2 channel layer. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Propose an edge contact model to evaluate the time-varying contact stiffness with local defect in roll. [•] Effect of local defect on dynamics of a Sendzimir twenty-high roll mill is studied. [•] The root mean square and the envelope spectrum are analyzed with different local defect sizes in roll. [•] The power spectral entropy is used to indicate the propagation of roll local defect. [Copyright &y& Elsevier]

Abstract: Minimum lubricant film thickness and maximum pressure every so often appear close to roller ends. This study combines the Boussinesq–Cerruti half-space equations with a free boundary correction procedure for precise modeling of edge contact conditions. The thermal EHL model developed associates this representation to a standard finite difference of the energy equation, and to a modified finite difference expansion of the Couette term of the Reynolds equation. To complete the model, the Carreau expression describes the shear-thinning response of the lubricant. The investigation includes different roller profile corrections. The results show that a large radius crowning modification combined with a rounding of the corners constitutes the most effective profile adjustment. [Copyright &y& Elsevier]

The science and engineering of two-dimensional materials (2DMs), in particular, of 2D semiconductors, is advancing at a thriving pace. It is well known that these delicate few-atoms thick materials can be damaged during the processing toward their integration into final devices. Thermal scanning probe lithography (t-SPL) is a gentle alternative to the typically used electron beam lithography to fabricate these devices avoiding the use of electrons, which are well known to deteriorate the 2DMs' properties. Here, t-SPL is used for the fabrication of MoS 2 -based field effect transistors (FETs). In particular, the use of t-SPL is demonstrated for the first time for the fabrication of edge-contact MoS 2 FETs, combining the hot-tip patterning and Ar + milling to etch the 2DM. To avoid contamination of the contact interface by atmospheric gas molecules, etching and metal deposition are performed without breaking the vacuum conditions in between. With this process, edge-contact MoS 2 FETs are successfully fabricated and characterized. On/off ratios up to 10 8 and 10 9 are obtained at room temperature in air and vacuum, respectively, i.e., comparable with the best values reported in the literature.