Circular Mode Research Articles

До порівняльної оцінки триланкових автобусів різних компонувальних схем за стійкістю руху

The article develops a mathematical model describing the movement of a three-link articulated bus (two-axle bus and two single-axle trailers), further ТAВ, as a four-mass system, taking into account the control wheel module of the bus. The system allows to study the influence of the design parameters of the bus and trailers on the stability of the ТAВ. The object of the study is the stability of the articulated bus with drive either on the axle of the bus or on the axle of the first trailer. The purpose of the work is a comparative evaluation of articulated buses with drive either on the bus axle or on the axle of the trailer in terms of stability. Research methods – mathematical modeling of the stability of the movement of a three-link articulated bus (two-axle bus and two uniaxial trailers) with drive either on the bus axle or on the axle of the first trailer. As a result of the study, it was found that at the selected values of the design parameters of the ТAВ, the critical speed when applying traction to the bus axis was 31.19 m / s, which exceeds the maximum speed of its movement. When implementing traction on the axis of the trailer, the loss of stability of circular stationary modes is realized at values of 0.08 <alpha <0.09 (alpha – coefficient determining the share of normal reaction of the bearing surface on the wheels of the bus or trailer driving wheels), and the loss of stability of rectilinear motion – at alpha = 0,0815. The critical velocity in this case is vkp = 12.34 m / s. Analysis of the conditions of static stability of the ТAВ during the implementation of traction on the axis of the trailer showed that the value of the drag coefficient does not affect the critical speed (not included in the expression of critical speed), and the value of rolling resistance coefficients on the first and second axles slightly affects the critical speed . and a critical value of the alpha parameter that determines the amount of traction. At the same time, even with optimally selected stiffness and layout parameters, the critical speed of articulated buses does not exceed 12.5 m / s, that is, such buses need a special system of opposition. Keywords: articulated bus, stability, critical speed, traction force, driving mode, trailer, support surface reaction.

Investigation of modal electromagnetic propagation across magnetic chiral interfaces without and with dielectric loss

Fresnel coefficients (FCs) corresponding to a lossless magnetic achiral/chiral (ACC) interface under variable angles of incidence (of s-polarized light) and permittivity/permeability ratios are derived including the nonmagnetic-magnetic case, examining possible anomalous Brewster and critical angle conditions. Bimodal and single-mode propagation (including also cases where both characteristic modes (right- and left-circular) in the chiral region enter evanescence) across a magnetic chiral/achiral (CAC) interface are then examined for possible anomalies. Simulation results are presented along with interpretations, supported extensively by verified tabular data. Finally, the concepts behind examining magnetic chiral interfaces in the presence of realistic dielectric loss are introduced for the ACC interface, indicating how the Snell’s laws are modified for each mode, and the decay behavior of the fields has to be rederived to accommodate the effect of loss. To introduce possible application areas, the characteristics of lossy, magnetic, and chiral slab resonators are presented, specifically relative to transverse resonances. Finally, a magnetic, chiral Fresnel zone plate is introduced via a methodology for examining its imaging and tuning properties relative to the two circular modes.

A study on the flow behavior and bubble evolution of circular oscillating laser welding of SUS301L-HT stainless steel

The flow characteristics, bubble formation and inhibition mechanisms of circular oscillating laser beam welding (OLBW) at distinct stages were elucidated in present work. The formation processes of bubbles mainly included the following manners. First, one or more of vortex P2, the recoil pressure flow P3, the migration flows FMF and BMF impinged the keyhole wall. The necking generated, gradually destabilized, and finally collapsed. Second, the self-instability of needle-like keyhole bottom (NKB) with large curvature induced the bubble formation. Third, complex melt flow broke the abnormal deformation of the keyhole or the bubble wall to form a new bubble. The bubble suppression mechanisms were summarized to three categories. First, the recoil pressure on the inner wall of bubble was at a low level, and the volume of bubble continually decreased until it collapsed. Second, high recoil pressure penetrated the metal liquid bridge between keyhole and bubble. Third, when recoil pressure was greater than the resultant force between surface tension and melt dynamic pressure, the bubble constantly fluctuated and gradually merged with the moving keyhole. As the frequency increased from 10 Hz to 200 Hz, porosity showed an exponential decrease from 7.16% to 0.35% in circular oscillation mode. A unified porosity prediction curve based on the Reynolds number was built with a coefficient of determination of 0.989. When fluid changed from laminar to turbulent flow, the critical Reynolds number was set as 1000, the predicted porosity was 0.912%, and the critical frequencies in circular and infinite oscillation modes were 143 Hz or 115 Hz, respectively, which were consistent with experiment results.

Machine Learning Models for Slope Stability Classification of Circular Mode Failure: An Updated Database and Automated Machine Learning (AutoML) Approach

Slope failures lead to large casualties and catastrophic societal and economic consequences, thus potentially threatening access to sustainable development. Slope stability assessment, offering potential long-term benefits for sustainable development, remains a challenge for the practitioner and researcher. In this study, for the first time, an automated machine learning (AutoML) approach was proposed for model development and slope stability assessments of circular mode failure. An updated database with 627 cases consisting of the unit weight, cohesion, and friction angle of the slope materials; slope angle and height; pore pressure ratio; and corresponding stability status has been established. The stacked ensemble of the best 1000 models was automatically selected as the top model from 8208 trained models using the H2O-AutoML platform, which requires little expert knowledge or manual tuning. The top-performing model outperformed the traditional manually tuned and metaheuristic-optimized models, with an area under the receiver operating characteristic curve (AUC) of 0.970 and accuracy (ACC) of 0.904 based on the testing dataset and achieving a maximum lift of 2.1. The results clearly indicate that AutoML can provide an effective automated solution for machine learning (ML) model development and slope stability classification of circular mode failure based on extensive combinations of algorithm selection and hyperparameter tuning (CASHs), thereby reducing human efforts in model development. The proposed AutoML approach has the potential for short-term severity mitigation of geohazard and achieving long-term sustainable development goals.

Oscillating laser welding of AZ31B magnesium alloy to DP590 dual-phase steel

Oscillating laser welding of AZ31B magnesium (Mg) alloy to DP590 dual-phase steel was performed in an overlap Mg-on-steel configuration with Sn foil added to lap joint, numerical simulation of laser energy distribution, temperature and flow fields inside molten pool was analyzed, and the effect of oscillating laser beam on microstructure and mechanical properties of joints were also investigated. A sound Mg/steel dissimilar joint is obtained under the beam rotation of oscillating laser assisted by Sn foil. Some defects, such as spatter and collapse, can be avoided in welding joints. In the case of circular oscillation mode, the shear force of joint reaches the maximum value of 1487 N when oscillation amplitude is 1.5 mm and oscillation frequency is 100 Hz, which is improved by 121.94 % compared with the non-oscillation mode. As laser beam oscillates, the uniformity of laser energy distribution is improved, the energy peak decreases. As a result, the laser action range increases and the joint width increases. In addition, the dendrites on both sides of molten pool are broken due to the increased flow and the enhanced vortex and convective effects induced by the rotation of keyhole. Hence, the performance of Mg/steel joint is improved.

Magnetoplasmonics beyond Metals: Ultrahigh Sensing Performance in Transparent Conductive Oxide Nanocrystals.

Active modulation of the plasmonic response is at the forefront of today's research in nano-optics. For a fast and reversible modulation, external magnetic fields are among the most promising approaches. However, fundamental limitations of metals hamper the applicability of magnetoplasmonics in real-life active devices. While improved magnetic modulation is achievable using ferromagnetic or ferromagnetic-noble metal hybrid nanostructures, these suffer from severely broadened plasmonic response, ultimately decreasing their performance. Here we propose a paradigm shift in the choice of materials, demonstrating for the first time the outstanding magnetoplasmonic performance of transparent conductive oxide nanocrystals with plasmon resonance in the near-infrared. We report the highest magneto-optical response for a nonmagnetic plasmonic material employing F- and In-codoped CdO nanocrystals, due to the low carrier effective mass and the reduced plasmon line width. The performance of state-of-the-art ferromagnetic nanostructures in magnetoplasmonic refractometric sensing experiments are exceeded, challenging current best-in-class localized plasmon-based approaches.

Compact dual-band rectangular T E10 mode to circular TM01 mode converter for telemetry/telecommand applications in satellite communication: design, equivalent circuit modeling, mode level measurement technique and 3d printed manufacturing

In this study, the design of a dual-band mode converter, which provides transition from rectangular waveguide T E10 mode to circular waveguide TM01 mode and operates simultaneously in telemetry/telecommand (TT&C) frequencies, is presented along with its equivalent circuit and a mode level measurement technique. This dual-band converter is designed to uniformly excite TT&C slot antennas used in satellite communication with symmetric circular TM01 mode. The structure can work as a transceiver due to having one common rectangular waveguide feed. As a Ku-band application, a converter giving high purity TM01 mode at circular waveguide at 11.75 GHz/TX and 13.75 GHz/RX center frequencies is designed and manufactured with 3D printing technology. Approximate equivalent circuit models of the designed structure are extracted by using lumped elements from simulated S-parameter results. In addition, a measurement technique to detect the normalized power levels of different propagation modes in dual-band mode converter is applied on the manufactured structures to obtain transmission levels of circular TM01 mode and suppression levels of circular T E11 mode. It is revealed from the measurement results that while the designed structure gives more than 17.5 dB return loss and suppression of T E11 mode, and less than 0.6 dB insertion loss of TM01 mode within 500 MHz bandwidth at TX band, it gives more than 23 dB return loss and suppression of T E11 mode, and less than 0.3 dB insertion loss of T M01 mode within 900 MHz bandwidth at RX band.

Teaching Reform of Double-center & Three-cycle Hybrid Mechanical Specialty

The ability of college students to discover, propose and solve engineering problems in machinery has become an essential part of a contemporary college education. Therefore, the teaching reform focusing on cultivating College Students’ ability to propose and solve engineering problems has become an essential part of a college education. Taking mechanical students as an example, this paper constructs a teaching content and method with “students” and “theory, engineering” as the double centres, combined with “pre-class”, “in-class” and “after class”, in which the teacher put forward the relationship between curriculum knowledge points and mechanical engineering problems, guide students to discover actively, learn and apply curriculum knowledge points, and put forward practical solutions to engineering problems in combination with mechanical engineering related issues. To achieve the goal of teaching engineering problems based on theoretical knowledge and practical operation, we should combine the “Internet plus” modern teaching tools to create “Online & Offline” mixed interactive courses and high-quality curriculum resources, forming the circular multi-dimensional closed-loop teaching mode of “student, theory, engineering” cycle, “pre-class, during-class, after-class” cycle and “before class test, instruction, after class test” cycle, which the students’ ability to master knowledge points in the teaching process.

Study on sex-linked region and sex determination candidate gene using a high-quality genome assembly in yellow drum

Yellow drum is marine fish species distributed in East Asia, exhibiting a sex-dependent dimorphic growth pattern where females grow much faster than males. The sex determination candidate gene and molecular mechanism were still unclear in yellow drum. The interpretation of sex chromosome sequences could shed light on sex determination. Herein, using high-fidelity (HiFi) reads generated with the PacBio circular consensus sequencing mode, we assembled and annotated a male genome of the yellow drum. The genome sequence assembly has a contig N50 size of 22.37 Mb and 98.17% of sequence length of contigs can be assigned to 24 chromosomes via Hi-C interaction data. Fst analysis demonstrated that the genetic divergence regions on sex chromosome occupied 2/3 of sex chromosome. The site with genotypes concordance (the male is heterozygous and female is homozygous) reached 100% in both males and females spanning from 14.9 – 24.9 Mb on sex chromosome, this 10 Mb region was designed as sex determination region (SDR). We integrated the RNAseq data generated with gonads of early development larvae and analyzed the expression of the genes located in SDR, suggested that dmrt1 might play as sex determination key gene in males of yellow drum. Subsequently, we screened out a Y chromosome contig (∼1.4 Mb) using a sex-linked marker. We found that there are two tandem dmrt1 genes in yellow drum, designated as dmrt1a and dmrt1b, and dmrt1b harbors a premature stop codon. A male-specific 438-bp deletion in the promoter of dmrt1a was successfully developed as a sex specific marker. Our study laid an important foundation for clarifying the sex determination mechanism in yellow drum and accelerating the production of all-female population.

Mechanical and microstructural properties of dissimilar copper and stainless-steel butt welds prepared using zigzag and circular fiber laser oscillation methods

Dissimilar copper and stainless-steel butt welds are prepared using zigzag and circular laser beam oscillation welding methods. The tensile strengths, microhardness values, and weld bead morphologies of the joints are evaluated and compared for various values of the oscillation amplitude and frequency. The optimal laser oscillation parameters are found to be a laser power of 1550 W, an oscillation frequency of 15 Hz, and an oscillation amplitude of 1 mm. Under these optimal processing conditions, the tensile strengths of the joints produced using the zigzag and circular oscillation welding modes are 232.6 MPa and 235.7 MPa, respectively. The superior strength of the weld produced using the circular oscillation method is attributed to a more uniform mixing of the alloying elements in the weld zone and a greater penetration depth. The addition of a thin Ni interlayer to the joint is found to improve the tensile strength to 240 MPa for the zigzag oscillation mode and 242 MPa for the circular oscillation mode. By contrast, the addition of a Ti interlayer reduces the tensile strengths of the joints to around 163 MPa and 198 MPa, respectively. The reduction in the tensile strength is the result mainly of a more brittle fracture mode within the heat affected zone (HAZ). Nonetheless, the circular oscillation welding mode results in a higher tensile strength than the zigzag mode due to a greater suppression of intermetallic compound (IMC) phase in the weld area and a reduction in the number of pores and cracks. Compared to conventional straight-line welding, the zigzag and circular oscillation modes reduce the grain size by around 32% and 52%, respectively, and enhance the mechanical properties accordingly.

Airy coherent vortices: 3D multilayer self-accelerating structured light

We propose and generate a class of structured light fulfilling the mathematical form of a SU(2) coherent state based on a set of circular Airy vortex modes. Such wave packets possess strong focus with both radial and angular self-accelerations, which exploit more general 3D inhomogeneous velocity control with global spatial symmetry of multilayer rotation akin to galactic kinematics, termed galaxy waves. Galaxy waves are endowed with higher degrees of freedom to control strong focusing and acceleration, which opens a direction of multi-dimensional accelerating of 3D structured light field, promising numerous applications in optical trapping, manufacturing, and nonlinear optics.

Improved electron trajectory and power distribution in APPLE-knot undulator.

The APPLE-Knot undulator has been proposed to reduce the large on-axis heat load of the APPLE-II at very low photon energy. However, the current designs have an inherent non-zero second field integral due to the Knot sections, resulting in a transverse deflection of the electron beam throughout the undulator. For a long device, such a deviation can degrade the brightness and power distribution of the outgoing beam. Here, a new end-Knot section is presented to compensate for the electron trajectory, and the undulator is symmetrized to balance the output power distribution. The performance of the APPLE-Knot with symmetric power distribution is investigated. The partial power, flux, and polarization are compared with the APPLE-II. In the linear mode, APPLE-Knot shows a pronounced reduction of the partial power, with a similar flux to the APPLE-II. The symmetric power density distribution reduces the hotspot by 41%, with a flux loss of less than 5%. In the circular mode and at low photon energies, the flux is limited by the phase error of the symmetric design.

Negative differential thermal conductance between Weyl semimetals nanoparticles through vacuum

In this work, the near-field radiative heat transfer (NFRHT) between two Weyl semimetal (WSM) nanoparticles (NPs) is investigated. The numerical results show that negative differential thermal conductance (NDTC) effect can be obtained in this system, i.e., when the temperature of the emitter is fixed, the heat flux does not decrease monotonically with the increase of the temperature of the receiver. Specifically, when the temperature of the emitter is 300 K, the heat flux is identical when the temperature of the receiver is 50 K or 280 K. The NDTC effect is attributed to the fact that the permittivity of the WSMs changes with the temperature. The coupling effects of polarizability of two WSM NPs have been further identified at different temperature to reveal the physical mechanism of the NDTC effect. In addition, the NFRHT between two WSM NPs can be greatly enhanced by exciting the localized plasmon and circular modes. This work indicates that the WSMs maybe promising candidate materials for manipulating NFRHT.

A Refined Closed-Form Solution for Laterally Loaded Circular Membranes in Frictionless Contact with Rigid Flat Plates: Simultaneous Improvement of Out-of-Plane Equilibrium Equation and Geometric Equation

Essential to the design and development of circular contact mode capacitive pressure sensors is the ability to accurately predict the contact radius, maximum stress, and shape of a laterally loaded circular membrane in frictionless contact with a concentric circular rigid flat plate. In this paper, this plate/membrane contact problem is solved analytically again by simultaneously improving both out-of-plane equilibrium equation and geometric equation, and a new and more refined closed-form solution is given to meet the need of accurate prediction. The new closed-form solution is numerically discussed in convergence and effectiveness and compared with the previous one, showing that it can greatly improve the prediction accuracy of the contact radius, maximum stress, and shape of the circular membrane in frictionless contact with the rigid flat plate.

Eigenmode analysis of dynamical many-body near-field radiative heat transfer mediated by an external magnetic field

• Eigenmode analysis is applied to the dynamical many-body near-field radiative heat transfer under an external magnetic field. • We identify near-field and far-field thermalization modes and the roles of magneto-resistance effect and directional heat flow. • The near-field mode can be largely slowed down by the magnetic field and is highly tunable via variation of the direction of the magnetic field. • The far-field mode is greatly enhanced by the magnetic field due to extra contribution of circular resonances. • The far-field mode is independent on the particle-particle near-field interaction, the spatial arrangement of the cluster and the direction of the magnetic field. In this work, we apply eigenmode analysis to the dynamical many-body radiative heat transfer (RHT) of an ensemble of magneto-optical (MO) nanoparticles under an external magnetic field. With the eigenmode analysis, we identify near-field and far-field modes of thermalization, each mode can dominate the dynamical many-body RHT depending on the temperature distribution of the nanostructures. The near-field thermalization modes, dominated by near-field RHT, tend to distribute the thermal energy uniformly through the ensemble at small time scales. The eigenmode analysis shows that the thermal magneto-resistance effect can slow down the near-field mode by an order of magnitude, which is highly sensitive to the direction of the magnetic field. The far-field mode is activated upon reaching uniform temperature distribution and occurs at much larger time scales, in which the nanoparticles thermalize with the background via far-field RHT, independent of the near-field interaction, the spatial arrangement of the ensemble and the direction of the magnetic field. The far-field mode, in contrast, can be greatly accelerated by the magnetic field due to the extra contribution of circular resonances. The eigenmode analysis also identifies circular thermalization modes in certain configurations, indicating the emergence of persistent directional heat flow and the thermal photonic Hall effect. Aided with eigenmode analysis, our work gives deep physical insights into the thermalization process of MO many-body nanostructures, revealing the important role of the magnetic field in the temporal and spatial control of many-body near-field RHT.

Time-Domain Simulation of Helical Gyro-TWTs With Coupled Modes Method and 3-D Particle Beam

A new self-consistent time-domain model for the simulation of gyrotron traveling-wave tubes with a helically corrugated interaction space (helical gyro-TWTs) is presented. The new model links classical methods using the approach of slowly varying variables together with an expansion of the electromagnetic field in eigenmodes and advanced full-wave particle-in-cell (PIC) solvers. The aim is to significantly reduce the required calculation time compared to full-wave PIC solvers, while less strict assumptions are introduced as in the classical approaches of slowly varying variables. For the first time, the classical theory of coupled circular waveguide modes for the description of the operating electromagnetic eigenmode in the helical interaction space is combined with a 3-D PIC representation of the electron beam. This allows the simulation of the beam–wave interaction over a broad bandwidth and at arbitrary harmonics of the cyclotron frequency. In addition, arbitrary electron beams (with spreads, offsets of the guiding center from the symmetry axis, and so on) can be investigated. The new approach is compared with the full-wave 3-D PIC code CST Microwave Studio. A good agreement of the simulation results is achieved, while the computing time is significantly reduced.

Wire Oscillating Laser Additive Manufacturing of 2319 Aluminum Alloy: Optimization of Process Parameters, Microstructure, and Mechanical Properties

In this study, a wire oscillating laser additive manufacturing (O-WLAM) process was used to deposit 2319 aluminum alloy samples. The optimization of the deposition process parameters made it possible to obtain samples with smooth surfaces and extremely low porosities. The effects of the deposition parameters on the formability and evolution of the microstructure and mechanical properties before and after heat treatment were studied. The oscillating laser deposition of 2319 aluminum alloy, especially the circular oscillation mode, significantly reduced the porosity and improved the process stability and formability compared with non-oscillating laser deposition. There were clear boundaries between the deposition units in the deposition state, the interior of which was dominated by columnar crystals with many rod- and point-shaped precipitates. After the heat treatment, the θ phase was significantly dissolved. The residual dot- and rod-shaped θ ' phases were dispersedly distributed, exhibiting an obvious precipitation-hardening effect. The samples in the as-deposited state had a tensile strength of 245–265 MPa, an elongation of approximately 12.6%, and an 87 HV microhardness. After heat treatment at 530°C for 20 h and aging at 175°C for 18 h, the tensile strength, elongation, and microhardness reached 425–440 MPa, approximately 10%, and 153 HV, respectively. The performance improved significantly without significant anisotropy. Compared with the samples produced by wire arc additive manufacturing (WAAM), the tensile strength increased by approximately 10%, and the strength and microhardness were significantly improved.

Analysis on the development direction of circular economy theory in automobile industry market and economic and technical conditions

With regard to the analysis of China's automobile industry market and development direction, we should not only consider the pulling effect of domestic economic growth, changes in consumption structure and industrial structure on automobile demand, but also the international experience of the relationship between per capita income level and automobile ownership rate, and more importantly, we should reflect on the traditional economic development model and find a new development model that effectively balances the relationship among economy, society, environment and resources. It is an inevitable trend for the development of automobile industry to take the circular economy mode, and it is the general trend of implementing the sustainable development strategy. In this situation, all kinds of technical ways to deal with the problems of resources and environment have their advantages and cannot be replaced. However, the research on circular economy of automobile industry in China has just started, and the basic material flow table and data analysis model of automobile products have not been established. This paper analyzes the traditional development mode of automobile industry, discusses the economic development direction of automobile industry and the development mode of circular economy in automobile industry, so as to keep up with the general trend of China's sustainable development strategy.

Broadband circularly polarized 2 × 2 MIMO array for midband 5G wireless applications

Abstract The novel compact size orthogonally fed 2 x 2 Multiple Input and Multiple Output (MIMO) array antenna for mid-band Fifth Generation (5G) wireless application is presented. The antenna configuration consists of diamond-shaped patches employed at the top of substrate. The V-shaped common ground slot structure is employed at the bottom of substrate. A broadband circular polarization is achieved by simply combining two circular polarization modes obtained from ground V slot and top patch feed structure. Mainly, the impedance bandwidth (IBW) and gain are enhanced by protruding slots on ground and cutting edges of patches. The measured result shows that 1.70 – 8.00 GHz (6.30 GHz) of IBW, 8.8 dBic of peak gain, and 3 dB axial ratio bandwidth from 1.81 – 3.87 GHz (2.06 GHz) are obtained. The proposed antenna performances are experimentally validated by fabricating and testing it for measured result analysis without using power divider.

Arbitrary higher-order optical spatial state generation by using spontaneously broken degeneracy modes in helically twisted ring-core hole assisted fibers.

A helically twisted ring-core hole assisted fiber (HAF) is proposed for an arbitrary higher-order spatial state generation. In usual circular core fibers, HE and EH modes are degenerate and have vector field distributions. We will show the degeneracy of these modes having specific azimuthal mode order is lifted by periodically placing air-holes around the core with specific symmetry while preserving their vector field distributions. It is called spontaneously broken degeneracy (SBD) in this paper. Azimuthal order of the SBD modes can be changed with the arrangement of surrounding air-holes. By using this SBD modes, it is shown that arbitrary higher-order spatial state generation, including orbital angular momentum (OAM) state, is possible based on a geometric phase existing in twisted fibers. Furthermore, by using periodically inverted twisting, efficient OAM state generation is possible by accumulating the geometric phase. The topological charge can be changed by changing the arrangement of surrounding air-holes. Since the mechanism does not depend on a phase matching, such as a long-period grating, but on a topological effect, the wavelength dependence is very small, leading to novel and efficient mechanism for the manipulation of the spatial state of the light.