Home – Home – Jornals – Thermophysics and Aeromechanics 2013 number 3

Single-mode optical fibers have been widely used in optical communications, and effective fiber lasers have been designed on the basis of active fibers with linear or ring cavities. In fiber lasers, the distance between the cavity mirrors can reach 270 km (the maximum length is determined by the linear attenuation and nonlinear dephasing of the waves). In 2009, random lasing was found in a long telecommunications fiber without any cavity: the positive distributed feedback required for lasing is due to Rayleigh scattering of light, and distributed amplification is provided by stimulated Raman scattering. Such a laser can be classified into the group of so-called random lasers, actively studied recently; the fiber geometry and the weakness of Rayleigh scattering provide much better output characteristics compared to the other types of random lasers. The lasing efficiency and beam quality of this laser are comparable to those of fiber lasers with a conventional cavity. At the same time, it has a number of unique features (unlimited length, and mode-free spectrum etc.), providing new physical phenomena and new opportunities for applications in telecommunications and sensor systems. The paper presents a review of recent results of studies in this area.

Methods of tuning and doubling of the generation frequency of fiber lasers are discussed. It is shown that the use of a KTP crystal for second harmonic generation makes it possible to develop effective tunable sources of radiation in the visible range.

Recent results of experimental investigations of parametric conversion of electromagnetic radiation in fibers are presented. The main attention is paid to the description of continuous-wave (CW) and pulse fiber optical parametric oscillators (FOPOs) operating in the spectral range from 0.5 to 2 µm. Requirements to obtaining effective generation and possible problems in FOPO design are discussed. Results of the development of a CW tunable FOPO with pump by an ytterbium-doped fiber laser, which allows generation of radiation with wavelengths shorter than 1 µm, are considered in detail.

This paper reviews studies of the possibility of controlling the output spectrum of Q-switched fiber lasers. Various laser configurations for producing output radiation with characteristics optimized for specific applications, such as high-power pulses for micromachining of materials, probe pulses in fiber-optic sensor systems, etc., are considered. The mechanism of broadening of the lasing line is elucidated, and methods for controlling the output spectrum in Q-switched all-fiber lasers are described. Frequency tuning in the amplification line and generation of higher harmonics in nonlinear crystals are considered.

The results of the design and study of femtosecond fiber lasers are reviewed. Various methods of mode-locking and generation regimes are considered. Special attention is paid to the regime of dissipative solitons in an all-fiber resonator with normal dispersion. The main results and analysis of the possibilities of energy scaling of femtosecond pulses are given.

Stimulated Raman scattering (SRS) of light in a single-mode optical silica fiber under excitation by a subnanosecond laser pulse with a wavelength of 532 nm is studied. The dependence of the SRS power and its spectrum on the laser pumping power is investigated. It is shown that, at relatively low pumping powers, SRS is well described by an exponential function predicted by the model, neglecting pumping depletion. At powers causing deviations from this dependence, the SRS band, whose value depends on the pumping power, is additionally broadened. Features of the broadening are similar to that of a laser line in an optical fiber. Intense anti-Stokes scattering on vibrational modes over-populated because of the SRS process is also observed.

Full-scale and computational experiments were used to investigate the flows in the jet thrust unit with annular nozzle and deflector in the form of a spherical segment. The used working gas was the combustion products of air mixtures with acetylene, gas-phase aviation kerosene, and natural gas. Experimental studies were carried out in a hot-shot wind tunnel in the range of stagnation pressure from 0.48 to 2.05 MPa. The calculations for the cases of combustion products outflow in terrestrial and high altitude conditions were performed with the original computer program that used the Euler and NavierStokes systems supplemented by equations of chemical kinetics. It was found that the thrust of the jet module with an annular nozzle at high altitude almost twice exceeds the sound nozzle thrust, but is lesser (about 25 %) than the thrust of the ideal calculated Laval nozzle; the difference therewith decreases markedly with the decrease of flight altitude and stagnation pressure.

An experimental investigation of the influence of mixing intensification by small-size jets on the startup and characteristics of a gas ejector with central nozzle and a convergent mixing chamber is carried out. It is shown that at high flow rates of the secondary gas, the critical regime is not settled because of the formation of a thick subsonic layer near the chamber wall. In these cases, a stepwise startup was done. The range of critical regimes is limited by the reloading point, at which the velocity near the chamber wall becomes sonic. The critical regime breakdown behind the reloading point occurs due to the upstream propagation of the back pressure through the subsonic layer. The mixing intensification ensures the equalization of the velocity profile and the extension of the range of critical regimes. Despite the improvement of characteristics the mixing in an ejector with the central nozzle remains incomplete. Experimental characteristics are compared with the computed ones. The mixing process is isobaric in the computation without the consideration of dissipative losses because of which the rise of the pressure of a mixture of primary and secondary gases occurs.

The influence of vibration on the behavior of the perfect viscous gas inside a rectangular cavity is investigated numerically. The heat and mass transfer processes in gas are compared in the region under the isothermal and adiabatic boundary conditions. The problem is solved in the one-dimensional statement.

A possibility to simulate a thick Clauser-equilibrium incompressible turbulent boundary layer on a flat plate of finite length with the help of a grid formed by cylindrical rods was experimentally examined. A grid with rods oriented parallel to the streamlined surface proved to be an efficient tool enabling modification of the turbulent boundary layer. In most cases, at a distance of 600 rod diameters the time-average and fluctuation characteristics of the modified boundary layer exhibited values typical of a natural turbulent boundary layer. It is shown that the mean velocity profiles with artificially increased boundary-layer thickness can be represented, to a good accuracy, in terms of law-of-the-wall variables, and they can be generalized with a single dependence using an empirical velocity scale in the outside region. The use of a combined method for exerting an influence on the shear flow capable of improving the modeling procedure for turbulent velocity fluctuations in boundary layer is proposed.

The conditions for possible reduction of hydrodynamic resistance by the compliant coatings are considered from two points of view: pulling the laminar flow and alteration of turbulence generation in the near-wall zone. A strong effect of the longitudinal pressure gradient and reasonability of the search for the laminarized bypass flows in the presence of compliant coatings are distinguished.

Results of a study of the optical response of liquid crystals with helical supramolecular structure to surface-friction-induced shear stress in aerodynamic experiments are reported. The effect of re-orientation of molecules from confocal (light-scattering) to planar (selectively reflecting light) texture is considered. The textural transition is examined by the spectral and colorimetric methods. Dependences of the reflection spectra of the formed planar texture on time and on the mean shear-stress level were obtained. It is shown that the dependence of the texture transition time on the shear-stress level can be approximated, in a logarithmic scale, with a linear dependence; this allows using the effect for flow diagnostics.

A new method of solution to the problem of stability of the swirl flow of viscous incompressi-ble fluid is developed. The method based on expansion of the required function into power series of radial coordinate allows an avoidance of difficulties related to numerical integration of the system of differential equations with a singular point. Stability of the Poiseuille flow in a rotating pipe is considered as an example.

Results of a parametric study of pressure characteristics of a perforated membrane in an oscillating liquid flow are reported. A diagram of an experimental facility for evaluation of the pressure produced by a perforated membrane in an oscillating flow is given.

The article is devoted to the evaluation of the role of science and higher education in the dynamics of development of the society on the global scale and in relation to Russia. There is proposed a law, according to which the rate of technological progress in the society is proportional to the level of payment of the higher education faculty. There is evaluated quantitatively and qualitatively the change of the role of Russia in the world science and education for the last 60 years. The greatest successes (entering the outer space, creating the nuclear missile shield, etc.) were achieved by the country in the years 1950 – 1960 due to the increase of the quality and role of public higher education and fundamental science. The decline in the prestige and payment in these areas of skilled labor, which occurred in Russia in the end of the last century, has reduced the role of Russia in the world in all areas.

In the article, civil society is considered as one of sophisticated social complexes, its definition is made, education as a factor of its formation is singled out. Also, the author considers the “innovation” concept in the pedagogical process.

There is considered in the article an educational correlate of the human being’s ability to transcend. In this philosophical-anthropological research, the author makes an attempt of theoretical comprehension of transcending as a mechanism of educational self-construction of the human being. A metaphysical idea of the possibility of final «completion of the human being» is criticized in the work. There is shown continuous educational processuality, which determines a self-creating way of existence of the human being. The author states a thesis about the necessity of using the onto-anthropological concept of «educational transcending» for theoretically effective study and description of education as a way of existence of the human being.

The article considers the problems of organization of the research education environment as a backbone factor of innovational activity. The structure of the education environment for the modern educational institution is described, this structure having been developed both in the “classical” and the innovation-generative versions.

The article deals with the world-systems interpretation of the «open» and «closed» societies. There are made critical remarks concerning the content of these concepts in K. Popper’s works. The main aim of the article is the explanation of the historical reasons of occurrence of the “open” and “closed” societies in the world-system history.

The article focuses on the philosophy of cinema and education of one of the most prominent post-structuralists of the Twentieth century Gilles Deleuze. It is based on his work “What is philosophy?” and the two-volume “Cinema”. There is noted the philosopher’s unusual approach to the problems of cinema and education, their common points are emphasized. Deleuze has developed the “pedagogy of perception”: the training of the film perception and of the experience virtualization. The article explains its essence and also reflects on the philosopher’s ideas about the relationship between philosophy and cinema, cinema and education.

A brief analysis of the antique educational paradigm is carried out in the article. The author indicates the absence of the modern domestic ideology of education, capable to answering both the general questions of education and the questions of its reforming. The author pays attention to the possibility of using some principles and methods of antique education for creation a modern domestic educational paradigm.

The article considers the problems of Russian technical education caused by the reducing in the educational standards the in-room studies of the basic subjects, which are the foundation for the formation of the highly qualified specialist (advanced mathematics, theoretical mechanics, theory of the strength of materials, theory of machines and mechanisms). The high speed of scientific and technical progress sets higher requirements for the training of the specialist with higher education. However, a decrease of the knowledge level is detected through the monitoring of the training quality. A trend analysis is carried out to highlight the consequences of the classroom load reduction in the educational standards concerning the machine-building subjects.

In the article, the problem of humanization of technical education is described, its social-philosophical aspect is considered, the questions about the problems of globalization of society and education are brought up. There is defined a set of problems which can be solved by creation of a new program of teaching of humanitarian disciplines in the technical college.

At the present time, the problems of managing the reputation and image of educational organizations are gaining a broad resonance in the educational field. In the unfolding competition, the institutions of higher education resort to the extensive use of Internet to enhance their communicational capabilities. Maintaining a positive image of the higher education institute on the Internet has an influence not only on the strengthening of its competitiveness and outlook for the future, but, in general, makes it possible to indicate the level of educational development in a region or a country. The author analyzes the characteristics of Internet reputation of the higher education institution and the factors which form the educational reputation. In the article, there is also described an online reputation management system and a set of possible actions to implement the process of management of the Internet reputation.

The author analyzes the potential of online-learning activities in the educational process in higher education. The development of the virtual communication environment provides many new opportunities for the training process organization. The author offers an option of integrating the traditional forms of practical training organization in the new communication environment. The article considers the types of online-activities that are conducted by commercial organizations, their strengths and weaknesses, as well as indicates the most prospective forms of the online-learning activities.

The current conditions of education development, the society’s demands and the challenges of modern time – all lead to a more urgent need for working out the philosophical-methodological foundations of didactics and applying the latter as a fundamental science to shape a higher culture of thinking. In which case (under which conditions) can the learner develop reflexive thinking, an active ability to resolve forthcoming problems and contradictions in professional life? This article addresses a number of problem questions, viewed through the prism of philosophical thought and its development, as well as through the methodology of science, in order to find out the causes of the present cognition issues and draft some ways to tackle them. The author considers the dialectical approach as a progressive efficient means.

A critical view on modern education reflecting the historical period of transition from the traditional system of education to a new high-quality one cannot be constructed outside the philosophical-methodological basis of the core aspect of education, which is didactics. The social philosophy of education and the methodology of the pedagogical science didactics are united by gnoseology (epistemology), the theory of the objective reality cognition that has a direct relation to the students and pupils’ cognitive process. In our experience, the quality of education is achieved by innovative knowledge tests and educational (training) testing, especially at the pre-examination stage. The traditional testology, which is a science of monitoring and evaluating the quality of education, is used here in a new system of its synthesis with didactics, which is the theory of teaching. A functional integration of the two education-related sciences (didactics and testology) produces the surprisingly progressive results.

The authors raise a question of the methodological and theoretical foundation of the modern dissertation research as one of the criteria of its evaluation. The authors describe the current state of the problem of conceptual-categorical framework of research. Some examples of reasonable choice of the methodological foundation in various pedagogical dissertation researches are given in the article.

The role of evaluation system in the development of educational process is described in this article. The nature and specificity of the evaluation process in the school are revealed. The article deals with the reasons which reduce the students’ results in school. The modern methods of the students’ knowledge evaluation are examined and analyzed. Also, some ways to improve the evaluation organization in school are suggested.

To reach their goals, the institutions of higher education employ the quality monitoring. The information, collected as a result of such monitoring, allows making informed management decisions and identifying the problem areas, which are then targeted with specific measures and improvement programs. This article describes the quality management system tools, which has been successfully implemented for quality monitoring of the educational processes in the Siberian University of Consumer Cooperatives.

The article describes the contemporary requirements to the teacher’s professional competence and the ways of additional training of the teachers in the context of development of the domestic system of education. A special attention is given to the specificities of the program development and its implementation under conditions of the module technology, which provides the practice-transforming activity, awareness of teacher’s own abilities and the development of the individual educational program. As an example, there is presented a program of educational invariant normative-legal module as a part of the individual educational program.

In the article, the influence of educational group, as a socialization micro-factor, on the creative development of students is shown; an intrinsic characteristic is given of educational group as a small social group, as a group of contemporaries, as a precondition of social and personal development of students. From the point of view of philosophical approach, the concept of “creativity” is revealed; the creative development of students is considered in the aspect of the development of creativity as a general universal ability, being possessed to some extent by every person.

The article features the topical problems of the influence of PR on the formation of the cultural-ideological values of the youth. The author analyzes the functions of the media and their influence on awareness, self-consciousness and intelligence of young people.

In the article, the modern models of education are analyzed: the traditional and the humanistic ones. There is described a new technology of education, coaching, which has appeared relatively recently: its principles, methods, techniques and areas of application are presented. The possibility is discussed of using coaching in modern conditions as a tool promoting realization of the principles of the humanistic educational model.

The author analyzes various approaches to the formation of metacognitive structures of cognitive activity and their roles in the development of general culture of thinking in the process of education. The article studies the impact of these approaches on the formation of modern educational strategies and models. There is shown the specificity of formation and development of cognitive and metacognitive structures of consciousness and thinking in the context of the traditional subject of study in the process of developing education, focused on the metasubject contents. There is substantiated the need of taking into account the distinctions of the metacognitive structures organizing logical thinking in its classical understanding, and the narrative language categories and structures. A conclusion is made about the necessity and prospects of development of new models of education aimed at the development of metacognitive structures of consciousness and abilities to reflect the categories, which organize thinking and language means.

The methodological bases of studying socialization of the person with limited opportunities of health in inclusive education are presented in article. At the philosophical level of methodology, socialization of the person with limited opportunities of health is considered as a form of manifestation of the general philosophical category of “development” on the basis of 3 dynamic pairs of concepts. At the general scientific level of methodology, socialization of the person with limited opportunities of health is analyzed through the prism of the synergetic, the activity and the subject subject approaches.

The methodology of developing creative abilities of the person is based on the philosophical theses about the essence of the human being and his/her activity, as well as on the creative thinking concept which is based on dialectical logic. The dialectical laws manifest themselves by revealing the unity of the processes of development and creation; hence, there arises the primary theoretical foundation for understanding of creation. The phenomenology of creativity is considered through the chess players’ creative activity.

The work presents the rationale of development of multifunctional components and devices on children’s clothing as the psycho-pedagogical means of prevention the psycho-emotional disorders and psychosomatic disorders in preschoolers, related to the adverse emotional content of the parent’s relations with the child.