82 research outputs found
Π€ΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ ΡΠΌΠ΅Π½ΠΈΠΉ ΡΡΡΠ΄Π΅Π½ΡΠΎΠ² ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ·Π°
ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π° ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΡΠΌΠ΅Π½ΠΈΠΉ ΡΡΡΠ΄Π΅Π½ΡΠΎΠ² ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ·Π° Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΏΡΠ°ΠΊΡΠΈΠΊΠΎ-ΠΎΡΠΈΠ΅Π½ΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΠΏΠΎΠ΄Π³ΠΎΡΠΎΠ²ΠΊΠΈ, ΡΠΏΠΎΡΠΎΠ±ΡΡΠ²ΡΡΡΠ΅ΠΉ Π²Π½Π΅Π΄ΡΠ΅Π½ΡΠ΅ΡΠΊΠΎΠΉ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ° Π² ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
. ΠΡΠΎΠ²Π΅Π΄Π΅Π½ Π°Π½Π°Π»ΠΈΠ· ΡΠΎΡΡΠΎΡΠ½ΠΈΡ ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΡΠΌΠ΅Π½ΠΈΠΉ Π² Π ΠΎΡΡΠΈΠΈ. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ ΠΏΠ΅Π΄Π°Π³ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΡΠ»ΠΎΠ²ΠΈΡ, ΡΠΏΠΎΡΠΎΠ±ΡΡΠ²ΡΡΡΠΈΠ΅ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π³ΠΎΡΠΎΠ²Π½ΠΎΡΡΠΈ ΡΡΡΠ΄Π΅Π½ΡΠΎΠ² ΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ° ΠΊ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠΉ ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠΉ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ. Π‘ΡΠΎΡΠΌΡΠ»ΠΈΡΠΎΠ²Π°Π½ΠΎ ΠΏΠΎΠ½ΡΡΠΈΠ΅ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΎΠΉ ΠΊΠΎΠΌΠΏΠ΅ΡΠ΅Π½ΡΠΈΠΈ ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ°. ΠΠ±ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΎ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ΅ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΏΡΠΎΠ΅ΠΊΡΠΎΠ² Π΄Π»Ρ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΡΠΌΠ΅Π½ΠΈΠΉ ΡΡΡΠ΄Π΅Π½ΡΠΎΠ² ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ·Π°. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π° ΠΌΠΎΠ΄Π΅Π»Ρ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΡΠΌΠ΅Π½ΠΈΠΉ ΡΡΡΠ΄Π΅Π½ΡΠΎΠ² ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ·Π° Ρ ΡΡΠ΅ΡΠΎΠΌ ΠΏΡΠΎΠ΅ΠΊΡΠ½ΠΎΠΉ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ°.The developing methods of entrepreneurial competences of engineering students, based on the practice-oriented training to encourage an implemental activity of an engineer in the modern context has been presented in the report. The analysis of the problem of entrepreneurial competencies development in Russia has been carried out. The pedagogical conditions encouraging the commitment of the technical university students for an integrated engineering activity has been defined. The concept of entrepreneurial competencies of an engineer has been stated. An effective appliance of project methods to develop entrepreneurial competences of the engineering university students has been proved. There has been presented the development model of entrepreneurial competences of engineering students
ΠΠ²ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ Π·Π°ΠΊΠΎΡΠ°ΡΠΈΠ²Π°Π½ΠΈΠ΅ ΠΎΡΠ΄Π΅Π»ΡΠ½ΡΡ ΡΠ°Π· Π»ΠΈΠ½ΠΈΠΉ Π΄Π»Ρ Π»ΠΈΠΊΠ²ΠΈΠ΄Π°ΡΠΈΠΈ Π΄ΡΠ³ΠΎΠ²ΡΡ ΠΊΠΎΡΠΎΡΠΊΠΈΡ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΠΉ
During the last few years high power diode laser arrays have become well established for direct material processing due to their high efficiency of more than 50%. But standard broad-area waveguide designs are susceptible to modal instabilities and filamentations resulting in low beam qualities. The beam quality increases by more than a factor of four by using tapered laser arrays, but so far they suffer from lower efficiencies. Therefore tapered lasers are mainly used today as single emitters in external resonator configurations. With increased output power and lifetime, they will be much more attractive for material processing and for pumping of fiber amplifiers. High efficiency tapered mini bars emitting at a wavelength of 980 nm are developed, and in order to qualify the bars, the characteristics of single emitters and mini bars from the same wafer have been compared. The mini bars have a width of 6 mm with 12 emitters. The ridge waveguide tapered lasers consist of a 500 Β΅m long ridge and a 2000 Β΅m long tapered section. The results show very similar behavior of the electro-optical characteristics and the beam quality for single emitters and bars. Due to different junction temperatures, different slope efficiencies were measured: 0.8 W/A for passively cooled mini bars and 1.0 W/A for actively cooled mini-bars and single emitters. The threshold current of 0.7 A per emitter is the same for single emitters and emitter arrays. Output powers of more than 50 W in continuous wave mode for a mini bar with standard packaging demonstrates the increased power of tapered laser bars
ΠΠΊΠ»Π°Π΄ ΠΎΡΠ΅ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ Π»Π΅Π΄ΠΎΠΊΠΎΠ»ΠΎΠ² Π² ΠΎΡΠ²ΠΎΠ΅Π½ΠΈΠ΅ ΠΡΠΊΡΠΈΠΊΠΈ
The longitudinal carrier density distribution of an InGaAlAs high-power broad-area semiconductor laser has been measured using spontaneous emission from the side of the device. The laser shows continuously increasing carrier densities on the facet with the high reflectivity coating (reverse facet). This has a major impact on the efficiency and the lifetime of the laser. This behavior is in good agreement with one-dimensional calculations for the longitudinal carrier distribution
Dynamics of Viscoplastic Deformation in Amorphous Solids
We propose a dynamical theory of low-temperature shear deformation in
amorphous solids. Our analysis is based on molecular-dynamics simulations of a
two-dimensional, two-component noncrystalline system. These numerical
simulations reveal behavior typical of metallic glasses and other viscoplastic
materials, specifically, reversible elastic deformation at small applied
stresses, irreversible plastic deformation at larger stresses, a stress
threshold above which unbounded plastic flow occurs, and a strong dependence of
the state of the system on the history of past deformations. Microscopic
observations suggest that a dynamically complete description of the macroscopic
state of this deforming body requires specifying, in addition to stress and
strain, certain average features of a population of two-state shear
transformation zones. Our introduction of these new state variables into the
constitutive equations for this system is an extension of earlier models of
creep in metallic glasses. In the treatment presented here, we specialize to
temperatures far below the glass transition, and postulate that irreversible
motions are governed by local entropic fluctuations in the volumes of the
transformation zones. In most respects, our theory is in good quantitative
agreement with the rich variety of phenomena seen in the simulations.Comment: 16 pages, 9 figure
5 W high-efficiency high-brightness tapered diode lasers at 980 nm
Tapered diode lasers in external resonator configuration are suitable for applications such as frequency conversion or non-linear spectroscopy were narrow linewidth in combination with high output power is needed. In order to increase the brightness it is necessary to make the output power and the efficiency comparable to broad area lasers and simultaneously keep the beam quality nearly diffraction limited. For this purpose we have grown low modal gain, single quantum well InGaAs/AlGaAs devices emitting at 980 nm by molecular beam epitaxy. As an example of a tapered laser with an overall length of 3.5 mm, we achieved an optical output power of more than 5 W in continuous wave mode (cw)
Developments in tapered lasers at 980 nm to 1060 nm
High-brightness diode lasers are attractive for pumping of fiber lasers, raman amplification and other applications. The paper gives an overview about the development and current status of tapered high-brightness diode lasers
Metamorphic 50 nm InAs-Channel HEMT
A 50 nm gate length metamorphic HEMT with InAs-channel and InAlAs-barriers for high frequency low power applications has been developed. Using a composite channel layout with backside doping an on-state breakdown voltage of 1.2 V and a g(ind m) max/g(ind O) ratio of four at V(ind DS) = 1.2 V was achieved. A low g(ind m) dispersion of only 5 % was measured. The realized three-stage 70 GHz LNA shows a power dissipation as low as 1.9 mW with an associated small signal gain of 6 dB
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Cycling Characteristics of Human Lymphocytes In Vitro
Abstract The cycling characteristics of human peripheral blood lymphocytes in phytohemagglutinin-stimulated cultures were examined by means of a new technique employing radioautographic methods which assay the fraction of cells whose nuclei contain DNA polymerase utilizing exogenous and/or endogenous DNA primer-template capability. The fraction of cells labeled by these techniques increases 5-11 hr prior to the onset of DNA synthesis. Estimates of cell cycle time, G1 time, and fraction of cycling cells are made for the first 4 days in culture. Evidence is presented to support the hypothesis that daughter cells of the first divisions may be retired from cycle by virtue of loss of primer-template availability, rather than by loss of DNA polymerase
Reliability of 70 nm metamorphic HEMTs
The reliability and degradation mechanisms of 70 nm gate length metamorphic InAlAs/InGaAs HEMTs for low noise applications will be presented and discussed. Based an a 10% g(ind m max) failure criterion, a median time to failure of 10(exp 6) h and an activation energy of 1.3 eV in air were found. By comparing the electrical device characteristics before and after stress, gate sinking, ohmic contact degradation, and hot electron degradation were found to be the major failure mechanisms. The stress induced platinum diffusion into the semiconductor was quantified by cross-section TEM
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