Review of a Decade of Research on Disordered Anderson Localizing Optical Fibers

Nearly a decade ago, transverse Anderson localization was observed for the first time in an optical fiber with a random transverse refractive index profile. This started the development of a whole new class of optical fibers that guide light, not in a conventional core-cladding setting based on total internal reflection, but utilizing Anderson localization, where light can guide at any location across the transverse profile of the fiber. These fibers have since been used successfully in high-quality endoscopic image transport. They also show interesting nonlinear and active (lasing) properties with promising applications. This review will cover a brief history of these fibers with personal accounts of the events that led to their development in our research groups. It will then follow with recent progress and future perspectives on science and applications of these fibers.

Study of Wear and Redistribution Dynamic Forces of Wheel Pairs Restored by a Wear-Resistant Coating 15Cr17Ni12V3F

The relevance of this study lies in the need to research the wear process of the elements of dynamic systems and to establish the dependence of the geometric and structural characteristics of wheels restored by plasma surfacing with a coating of 15Cr17Ni12V3F on dynamic, cyclically varying loads. The study was aimed to establish the dependencies between the deviation of the wear area, the formation of contact and fatigue stresses, and the change in the phase structure of the wheel defect. It is important to justify the permissible limits of wear of the transverse profile in the contact zone of a wheel and ridge. The object of the study was the dynamic interaction of the “wheel–ridge–rail contact surface” system. To achieve the goal, the following methodology was adopted: kinematic analysis, strength calculation, the use of mathematical analysis in dynamic system modelling, virtual modelling in the SOLIDWORKS software environment of the GearTrax application, experiment planning, and model correction through the results of metallographic studies. The results of the study are presented as reasonable prediction criteria that consider contact cycles during the formation of fatigue stresses at the stage of defect origin. The process of the dynamic interaction of the contact worn profile of a wheel with a railway rail is explored. Polynomial equations are proposed to substantiate the optimal design and technological parameters of designing a railway carriage wheel. The permissible limits of wear of the transverse profile in the contact zone of the wheel and the ridge are justified while taking the coefficient of the reduction of contact stresses in the metal into account. The dependences of the change in static load on the utilization factor of the railway carriage load capacity are established. The dependences of changes in fatigue stresses on the design deviation of the contact area of wheel wear are established. It is confirmed that the stress concentration under cyclic loads is formed in the ferritic layers of the material structure before the appearance of wear.

FEATURES OF GROWTH OF PETIOLATE OAK IN ARTIFICIAL LINEAR PLANTINGS OF THE CENTRAL FOREST-STEPPE

The formation of artificial linear plantations with the participation of pedunculate oak is predetermined by agrotechnical and silvicultural methods of cultivation. Its share among the used other breeds is about 25%. At the age of 33, with the placement of planting places 5.0 x 3.0 m, the pedunculate oak has a high preservation (by 33.9%) in a three-row plantation, in relation to crops from four rows. The protective height in a narrower artificial linear plantation is 10.2 m, which is 1.24 times higher with a width of 20.0 m. In mixed oak-ash crops at the age of 45 years, the best growth and preservation of pedunculate oak is noted in relation to oak plantations pure in composition. For birch-oak crops, the influence of a fast-growing breed is characteristic. At the age of 54, the safety of pedunculate oak is 23.1%, the wind protection height is 19.1 m. Differences in the growth of species are one class of bonitet. In the central rows of pedunculate oak at the age of 30-49 years, the average height has a greater value and a smaller diameter in relation to the indicators of the edging rows (by 7.5-19.9%). A convex transverse profile of the plantation is formed, which is predetermined by the physiological characteristics of the development of the tree species.

FORMATION OF ARTIFICIAL PROTECTIVE LINEAR PLANTS IN THE CONDITIONS OF THE EXPERIMENTAL FARM OF FSBEI HE "VSAU"

Artificial protective linear plantings in the experimental farm of the Federal State Budgetary Educational Institution of Higher Education "VGAU" were created more than 60 years ago. English oak was used as the main species for cultivation in cultures. The plantings are presented with a width of 18.0 m to 35.0 m with the placement of rocks 1.5 - 5.0 x 0.7 - 3.0 m. Due to the abundance of self-seeding, a dense structure of the lower profile has formed. To study the characteristics of the growth and condition of rocks, test plots were laid in the ZFN according to generally accepted methods in forest inventory and protective afforestation. English oak has a preservation of 50.1-60.1% and, at the same time, its average diameter is from 23.8-25.3 cm, the average height is 20.8-24.0 m. The best results were noted in plantations where the English oak grown with Norway maple and yellow acacia when placed 5.0 x 3.0 m. Silvicultural and reclamation assessment of plantings 4a. When creating protective plantations with the participation of fast-growing species with a placement of 1.5 x 0.7 m, 2.5 x 0.7 m English oak. enter when separating it in rows from fast-growing rocks. In cultures at the age of 62 years with a predominance of pedunculate oak, a convex transverse profile of the plantation is formed and, at the same time, the height of the middle rows is 10.1% higher than the edging rows, the average diameter of the middle rows is less than the extreme ones by 7.5%. Protective plantations transform agricultural landscapes, change the ecology of the territory, serve as boundaries and boundaries of vegetation in inter-strip fields.

Application of Risk Assessment While Assigning the Surface Width of Multi-Lane Roads

Постановка задачи. Рассматривается задача назначения ширины покрытия многополосных дорог на основе риск-ориентированного подхода в соответствии с Федеральным законом Российской Федерации № 184-ФЗ «О техническом регулировании». Результаты. Впервые представлена применимость алгоритма оценки риска взаимодействия транспортных средств на многополосных дорогах на примере назначения требуемой ширины шестиполосной автомагистрали. На основе оценок риска решены следующие проблемы: определены требуемые параметры ширины покрытия для нормативных документов; установлены допустимые величины ширины покрытия при проектировании автомагистралей; даны рекомендации по совершенствованию поперечного профиля существующих автомобильных дорог при капитальном ремонте и реконструкции. Выводы. Установлено, что в нормативных документах по проектированию шестиполосных автомобильных дорог при проектном составе транспортных средств следует предусмотреть изменение нормированной ширины покрытия, увеличив ее до значения, при котором риск столкновения автомобилей не превысит допустимой величины 1⸱10. Statement of the problem. The problem of ensuring the safety of vehicles on a multi-lane roadway of the required width of coverage is considered on the basis of a risk-oriented approach, in accordance with the Federal law of the Russian Federation No. 184-FZ «on Technical Regulation». Results. The authors presented the applicability of the algorithm to assess the risk of interaction of vehicles on six-lane highways for determining regulatory performance; the required values of surfacing thickness for the design have been identified; recommendations on the improvement of the transverse profile when major repairs and reconstruction have been provided. Conclusions. It was found that in normative documents for designing six-lane roads, the design vehicle should provide the change of normalized coating thickness, increasing it to values where the risk of collision of vehicles does not exceed the permissible value.

DESIGN ASPECTS OF INSTALLATION DEVICES OF THE SUPPORT RINGS

The processes of manufacturing machines and appliances show a continuous tendency to increase the degree of automation. An important role in the automation of manufacturing processes is played by the constructive technologicality of the product. It is important to use a minimum number of components, which have a construction as technological as possible in terms of automation. In this context, the use of supporting rings as fasteners is welcome. The design of the installation devices of these rings requires the knowledge of their deformation forces, information that is missing in the profile literature. The authors set their goal to develop the method for calculating the forces required to deform the supporting rings with a rectangular transverse profile and their maximum allowable deformations. The calculation relationships were obtained by formalizing the supporting ring through a bar with a fixed end and studying its deformation using Mohr's integral. The article lists some types of the supporting rings used in the construction of machines and appliances, their advantages and disadvantages, aspects of their automatic installation: deformation and installation methods, precision of joint orientation, optimal design, calculation of forces required for deformation and the maximum permissible deformation value. As a result of the research carried out, recommendations were developed regarding the calculation of some constructive parameters of the devices for installing the supporting rings.

A Unified Theory for 3D Gear and Thread Metrology

We propose a unified theory for the metrological treatment of helical machine elements such as cylindrical and conical gears, worms, and screw threads. The main idea is to introduce a universal 3D geometry model for threaded components that provides for distinct parameterization using a unique set of geometry parameters and that offers and a functional description of the transverse profile. Using modern 3D coordinate measuring technology, a holistic evaluation algorithm yields the actual geometry as the result of a high dimensional best-fit procedure and form deviations as corresponding residuals. All determinants and evaluation parameters can then be calculated from the set of actual geometry parameters. By applying certain constraints to the model to be fitted, the novel method can be reduced to the established 2D methods and hence meets demands for the comparison of the two procedures. The results of the novel approach have proven to be very stable and they enable the evaluation of areal measurements with no loss of information.

THE PROCEDURE OF ANALYSIS, ASSESSMENT AND RISK REDUCTION OF VEHICLE COLLISIONS ON A MULTI-LANE ROAD

Statement of the problem. The problem of ensuring the safety of vehicles on a multi-lane roadway of the required width of coverage is considered based on the risk-oriented approach, in accordance with the Federal law of the Russian Federation No. 184 -- FZ "on technical regulation". Results. The authors presented the applicability of the algorithm to assess the risk of interaction of vehicles on six-lane highways for determining regulatory performance; identify the required values of coating thickness for the design; decision-making on the improvement of the transverse profile when major repairs and reconstruction, as well as to develop recommendations for ODD. Conclusions. It was found that in normative documents for design of six-lane roads, the design vehicle should provide the change of normalized coating thickness, increasing it to values at which the risk of collision of vehicles does not exceed the permissible value.

Hob cutter shaping for internal straight thread

Резьба используется во многих механизмах и достаточно часто для разъемных соединений деталей судовых машин. Для повышения долговечности внутренней цилиндрической резьбы и производительности процесса ее нарезания предлагается новая методика «профилирования червячной фрезы для нарезания внутренней цилиндрической резьбы методом огибания. В данной статье приведено аналитическое определение сопряженных профилей цилиндрической внутренней резьбы и инструмента. Рассматривается метод профильных нормалей для профилирования червячной фрезы при нарезании внутренней резьбы способом огибания, основанный на применении теории матриц. Червячная фреза в осевом сечении имеет конкретный криволинейный профиль, для его получения необходимо знать расчетные зависимости торцового профиля резьбы, и уравнения ее винтовой поверхности и осевого профиля. Для возможности образования витков резьбы необходимы определенные зависимости скорости резанья фрезы и резьбы, а для формирования внутренней резьбы - ее поверхность должна набегать на зубья червячной фрезы. Эти задачи решены с помощью разработанной системы уравнений для изготовления фрез при нарезании внутренней цилиндрической резьбы способом огибания методом профильных нормалей. Расчетный механизм профилирования инструмента - фрезы для нарезания цилиндрических внутренних резьб – может применяться для формообразования конических внутренних резьб. Threads are used in many mechanisms and frequently in detached connections of marine engines elements. The new technique of hob cutter shaping for internal straight thread is proposed in order to increase durability of the internal cylindrical thread and to improve its cutting performance process. The article gives analytical definition of conjugate profiles of internal straight thread and of a tool. It also deals with the method of profile normals for shaping hob cutter whilst cutting the internal thread by enveloping. The method applies the matrix theory. There is some curved profile in the hob cutter axial section. In order to obtain that profile, it is necessary to know the calculated dependence of a thread transverse profile and its helical surface and axial profile equation. Special dependences of thread speed range and cutting are required to produce turns of the thread. To form internal thread – its surface is to slide on cutter teeth. All the mentioned tasks can be solved by the system of equations for cutters manufacture with cutting internal straight thread applying enveloping with the method of profiles normals. The calculation mechanism for shaping the tool – the hob cutter for internal straight threads – can be used for making internal taper threads.

Propagation Characteristics of Vortex Beam Using Visualization Analysis in Free Space

We theoretically analyze the linear momentum density and orbital angular momentum (OAM) propagation characteristics of Gaussian vortex beams in free space, and perform detailed numerical simulation analysis of the linear momentum density and OAM propagation characteristics. Further, we study the variation of the propagation characteristics with different topological charges. In addition, we also analyzed the position of momentum in the transverse profile, where the momentum density of the spot will be broadened with propagation distance. This study can provide guidance for using vortex beams in optical communication and manipulation.