Plasmonic Nanobar-on-Mirror Antenna with Giant Local Chirality: a New Platform for Ultrafast Chiral Single-Photon Emission

Providing an additional degree of freedom for binary information encoding and nonreciprocal information transmission, chiral single photons have become a new research frontier in quantum optics. Without using complex external...

MATHEMATICAL JUSTIFICATION OF STABILITY OF STEERING BRIDGE OF WHEELED TRACTOR

The article deals with the influence of wheel oscillation and the micro-profile of the road surface on the stability of the wheel tractor axle movement. The reasons for the oscillations of the steered wheels, the design diagram of the controlled axle of the tractor and the sequence for determining the oscillation frequency of the axle of the tractor are presented. The reasons for the oscillation of the steered wheels are collisions with bumps, imbalance of the wheels and a double connection with the tractor frame through the steering system and the fastening of the steering axle beam. The most common functions for describing road irregularities that affect the movement of a tractor are the mathematical expectation and the average value of the ordinates of the micro-profile, the variance or standard deviation of the ordinates, the correlation function characterizing the relationship of various implementations of the micro-profile functions along the length of the road section and spectral density. Oscillations of the steered wheels have a side effect on the stability of the tractor, which leads to oscillations of the steered axle due to the presence of an additional degree of freedom (turning around the pivot) in comparison with uncontrolled ones. In addition, the steered wheels are interconnected by a steering linkage, which is damped due to clearances. Oscillations of the wheels can also occur due to the fact that the radial (normal) stiffness of the tires around the circumference is not the same. When such a tire rolls, the wheel begins to oscillate in a vertical plane. Such oscillations, performed due to changes in the parameters of the oscillatory system, are called parametric. Self-oscillations of the steered wheels cause significant dynamic loads on the steering parts, intense tire wear and lead to a loss of tractor controllability and driving stability. One of the main reasons for the occurrence of oscillations of the steered wheels is the presence of a gyroscopic relationship between the angular oscillations of the beam of the steered bridge in the transverse plane and the rotation of the wheels of this bridge relative to the pins. The article also discusses the physical essence of the processes occurring during self-oscillations of the tractor's controlled wheels.

Photoluminescence enhancement with all-dielectric coherent metasurfaces

Mie resonances have recently attracted much attention in research on dielectric metasurfaces, owning to their enriched multipole resonances, negligible optical loss, and efficient light emitter integration. Although there is a rapid advancement in this field, some fundamental developments are still required to provide a simpler and more versatile paradigm for photoluminescence (PL) control. In this work, we proposed that an all-dielectric coherent metasurface can engineer the PL response by tuning the array size. Such PL manipulation is attributed to the collective Mie resonances that mediate the inter-unit interactions between unit elements and alter the PL intensity. Metasurfaces with different chip sizes are utilized to explore the array size effect on the collective Mie resonances, field enhancement, and Q-factor in TiO2 metasurfaces. Incorporating the all-dielectric coherent metasurface with fluorescent photon emitters, we performed the dependence of PL enhancement on array size, which achieves an enhancement factor of ∼10 at the central area of a 90 × 90 μm2 TiO2 metasurface array. These findings provide an additional degree of freedom to engineer the near-field confinement and enhancement, allowing one to manipulate incoherent photon emission and tune light–matter interaction at the nanoscale.

Development of environmental measures to reduce the dusty emissions of stone coal in loading and unloading works

Now Russia is one of the worlds leading coal producers. Particles inevitably pass into an aerosol state, forming dust, which is subsequently emitted into the atmosphere during the extraction, crushing, sorting and transportation of coal. This dust negatively affects the health of workers in the mining industry, as well as the population of the residential area. In this regard, the question arises about the effective air cleaning in the working area from coal dust and reducing its concentration. The work purpose is to develop a comprehensive cleaning of gas-air emissions from coal dust in the working area where it is transported. The main task is to create an additional degree of air purification from coal dust. For this purpose, a vortex absorber was used, which is a cylindrical apparatus in which a contact element with perforated holes is located. The geometric dimensions of the absorber and its main parameters have been determined. The absorber developed by the authors has shown very good results as a device for the final purification of gas-air emissions. The efficiency of trapping small solid particles in the presented scheme reaches 99%. At the same time, as a result of the introduction of this installation, effective air purification from dust particles with a diameter of about 0.2 microns is carried out and the coal briquettes production is increased by 144 tons per year.

Controlling valley polarisation in graphene via tailored light pulses

Analogous to charge and spin, electrons in solids endows an additional degree of freedom: the valley pseudospin. Two-dimensional hexagonal materials such as graphene exhibit two valleys, labelled as $\mathbf{K}$ and $\mathbf{K}^{\prime}$. These two valleys have the potential to realise logical operations in two-dimensional materials. Obtaining the desired control over valley polarisation between the two valleys is a prerequisite for the logical operations. Recently, it was shown that two counter-rotating circularly polarised laser pulses can induce a significant valley polarisation in graphene. The main focus of the present work is to optimise the valley polarisation in monolayer graphene by controlling different laser parameters, such as wavelength, intensity ratio, frequency ratio and sub-cycle phase in two counter-rotating circularly polarised laser setup. Moreover, an alternate approach, based on single or few-cycle linearly polarised laser pulse, is also explored to induce significant valley polarisation in graphene. Our work could help experimentalists to choose a suitable method with optimised parameter space to obtain the desired control over valley polarisation in monolayer graphene.

Research of the chisel with multi-operation working bodies for tillage

The mechanized technologies applied in Russia in vineyards are characterized by 2.5-3.4 times higher energy costs comparing to foreign countries. It is necessary to improve the methods of mechanized tillage in vineyards in order to reduce energy costs while maintaining quality. The purpose of the study is to develop mechanized universal technical means and working bodies for processing vineyard rows with the lowest energy consumption without damaging the root system of the bushes. The designed multi-stage chisel is capable of performing multi-tiered tillage in accordance with the architectonics of the root system of the bushes. The depth of loosening is 9-45 cm. The original design of the working bodies of the chisel with the additional degree of freedom provides reduction in traction resistance by 12-14% and specific energy consumption by 1.2 and more times. Chisel complies with agrotechnical requirements for the implementation of quality indicators of the technological process. The number of fractions of up to 50 mm is 57.5-76.5%, lumps of over 100 mm is 8-9%. The versatile design of the multi-operational horticultural and vineyard chisel will allow it to be used in the cultivation technologies of not only fruit and berry, but also grain and row crops.

Redesigning the Jefferson Lab Hall A beam line for high precision parity experiments

The Continuous Electron Beam Accelerator Facility (CEBAF) was built with a thermionic electron source and the three original experimental hall lines reflected this. A few years after beam delivery began a parity violation experiment was approved and two polarimeters were installed in the Hall A beam line. The beam raster system was placed after the new Compton polarimeter, before one accelerator quadrupole and four quadrupoles in the new Moller polarimeter. It was very difficult to meet experimental requirements on envelope functions and raster shape with this arrangement so a sixth quadrupole was installed downstream of the Moller polarimeter to provide an additional degree of freedome. All of the parity experiments in Hall A have been run with this still-unsatisfactory configuration. The MOLLER experiment is predicated on achieving a 2% error on a 32 ppb asymmetry. Beam line changes are required to meet the systematic error budget. This paper documents the existing beam line, an interim change which can be accomplished during a annual maintenance down, and the final configuration for MOLLER and subsequent experiments.

Gain-Assisted Optical Pulling Force on Plasmonic Graded Nano-Shell with Equivalent Medium Theory

The tunable optical pulling force on a graded plasmonic core-shell nanoparticle consisting of a gain dielectric core and graded plasmonic shell is investigated in the illumination of a plane wave. In this paper, the electrostatic polarizability and the equivalent permittivity of the core-shell sphere are derived and the plasmonic enhanced optical pulling force in the antibonding and bonding dipole modes of the graded nanoparticle are demonstrated. Additionally, the resonant pulling force occurring on the dipole mode is shown to be dependent on the aspect ratio of the core-shell particle, which is illustrated by the obtained equivalent permittivity. This shows that the gradation of the graded shell will influence the plasmonic feature of the particle, thus further shifting the resonant optical force peaks and strengthening the pulling force. The obtained results provide an additional degree of freedom to manipulate nanoparticles and give a deep insight into light–matter interaction.

MULTI-PURPOSE CHISEL FOR SOIL TREATMENT IN VINEYARDS

Used in Russia mechanized technology in the vineyards characterized by an increase in en-ergy costs 2.5–3.4 times compared to foreign countries. Most of the energy costs account for processing vineyard soil. It is necessary to improve the methods of mechanized soil cul-tivation in vineyards in terms of reducing en-ergy consumption while maintaining quality. The aim of the study is to develop mecha-nized universal technical means and working bodies for processing row-spacing of vine-yards with the lowest energy consumption without damaging the root system of the bushes. The designed multioperational chisel is capable of performing tiered tillage in ac-cordance with the architectonics of the root system of the bushes. Loosening depth 9–45 cm. The original design of the working bodies of the chisel with an additional degree of freedom provides a reduction in traction resistance by 12–14% and specific energy consumption by 1.2 and more times. Chisel complies with agrotechnical requirements in terms of fulfilling the quality indicators of the technological process. The number of frac-tions up to 50 mm 57.5–76.5 %, lumps over 100 mm 8–9 %. Universal design multiopera-tional garden and vineyard chisel allow its use in technologies of cultivation not only fruit, but also grain and row crops.

Various multipole combinations for conical Si particles

In this work, we investigated the possibility of creating various multipole combinations in conical silicon nanoparticles. It was found that in conical silicon particles it seems possible to create key effects for nanophotonics, such as various kinds of Kerker effects (Generalized Kerker, Transverse Kerker), Hybrid anapole state, Bound states in the continuum. This greatly simplifies the manufacturing process of photonic devices due to the easier production of nanocones in practice. Also, conical particles allow an additional degree of freedom, which opens up new horizons for obtaining previously unknown effects.