A novel optical injection-locking configuration utilising Brillouin amplification in optical fibre feedback is reported. The proposed structure exhibits properties inherent in two phenomena, self-injection locking and injection-locking in master-slave configuration at the same time. Significant narrowing of the locked DFB laser linewidth was recorded. The configuration provides intensity-stable Stokes generation without a high-frequency external modulator and generator. 相似文献
Supersonic jet pumps are simple devices with no moving parts, where a high velocity (primary) flow is used to pump a second
fluid. In this paper, Computational Fluid Dynamics (CFD) is combined with an optimization framework in order to develop a
tool for the rapid generation of jet pump designs. A key feature of the problem formulation is the transformation of the jet
pump design parameters in terms of geometric ratios. This approach dramatically reduces the number of unrealistic designs
covered by the Design of Experiments. Optimal Latin Hypercubes for surrogate model building and model validation points are
constructed using a permutation genetic algorithm and design points are evaluated using CFD. Surrogate models of primary and
entrained flow rates are built using a Moving Least Squares approach. A series of optimizations for various pump sizes are
performed using a genetic algorithm and Sequential Quadratic Programming, with responses calculated from the surrogates. This
approach results in a set of optimized designs, from which pumps for a wide range of flow rates can be interpolated. 相似文献
For powdered tungsten alloys with carbide and carbooxide strengthening it was established that in recrystallization there are three regions of structural changes characterized by different activation energy.
2.
In deformed powdered alloys with additions of Y2O3 and HfC+C deformation (diffusion) contrast on subgrain boundaries and relaxation of subboundaries at the initial stages of polygonization were discovered.
3.
Formation of particles of the second phase in powdered tungsten alloys leads to an increase of the temperature of onset of structural changes by 200–400°C in comparison with unalloyed tungsten, and the maximal effect there is attained upon formation of finely disperse particles of the carbide HfC.
A. A. Baikov Institute of Metallurgy. Scientific and Production Association "Tulachermet". Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 23–26, January, 1988. 相似文献
Metallurgist - The production of pellets from a concentrate of oxidized ferruginous quartzites that are tailings at the Mikhailovsky GOK pelletizing plant is studied. The conditions for the... 相似文献
In this paper, a dropout prediction method for e-learning courses, based on three popular machine learning techniques and detailed student data, is proposed. The machine learning techniques used are feed-forward neural networks, support vector machines and probabilistic ensemble simplified fuzzy ARTMAP. Since a single technique may fail to accurately classify some e-learning students, whereas another may succeed, three decision schemes, which combine in different ways the results of the three machine learning techniques, were also tested. The method was examined in terms of overall accuracy, sensitivity and precision and its results were found to be significantly better than those reported in relevant literature. 相似文献
In this work a two step approach to efficiently carrying out hyper parameter optimisation, required for building kriging and gradient enhanced kriging metamodels, is presented. The suggested approach makes use of an initial line search along the hyper-diagonal of the design space in order to find a suitable starting point for a subsequent gradient based optimisation algorithm. During the optimisation an upper bound constraint is imposed on the condition number of the correlation matrix in order to keep it from being ill conditioned. Partial derivatives of both the condensed log likelihood function and the condition number are obtained using the adjoint method, the latter has been derived in this work. The approach is tested on a number of analytical examples and comparisons are made to other optimisation approaches. Finally the approach is used to construct metamodels for a finite element model of an aircraft wing box comprising of 126 thickness design variables and is then compared with a sub-set of the other optimisation approaches. 相似文献
Silica glass was implanted with negative 60 keV Cu ions at an ion flux from 5 to 75 μA/cm2 up to a fluence of 1 × 1017 ions/cm2 at initial sample temperatures of 300, 573 and 773 K. Spectra of ion-induced photon emission (IIPE) were collected in situ in the range from 250 to 850 nm. Optical absorption spectra of implanted specimens were ex situ measured in the range from 190 to 2500 nm.
IIPE spectra showed a broad band centered around 560 nm (2.2 eV) that was assigned to Cu+ solutes. The band appeared at the onset of irradiation, increased in intensity up to a fluence of about 5 × 1015 ions/cm2 and then gradually decreased indicating three stage of the ion beam synthesis of nanoclusters: accumulation of implants, nucleation and growth nanoclusters. The IIPE intensity normalized on the ion flux is independent on the ion flux below 20 μA/cm2at higher fluences. The intensity of the band increased with increasing samples temperature, when optical absorption spectra reveal the increase of Cu nanoparticles size. 相似文献
Experience shows that the successful introduction of automated information systems at metallurgical enterprises largely depends on the technology and software selected. In the present work, the basic technology and software options available are briefly outlined. The starting point is Agile development, which is based on iterative procedures, the dynamic formation of user requirements, and their implementation through constant dialog within working groups consisting of various specialists (users, analysts, programmers, and testers). Iteration corresponds to relatively brief development times (as a rule, months), after which the user is given the next tested version of the software, with new functional properties. The list of additional functional properties in each new version represents user priorities and is drawn from the overall list of requirements before each iteration begins. In each iteration, the following procedures are completed in sequence: verification of the computational algorithm (with the introduction of new variables, where necessary); functional modeling of the system; improvement of subsystem structure; conceptual modeling of the database; generation of a model of the database; loading of the test data in the database; creation of the functional diagrams in the mathematical library; implementation of the subsystem’s client software; testing and debugging of the software; and the development of reference documentation. The Atlassian JIRA system is used to control individual tasks and monitor their overall realization within the process of collective software development. The Atlassian Bitbucket platform provides remote storage for code storage and control of the software version. On the basis of up-to-date approaches to software development, systems that are functional, reliable, east to use, expandable, and integrable may be created. Such systems are characterized by minimum risk and acceptable cost. 相似文献