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931.
Ozone measurement based on the optical absorption of visible light at 603 nm using polymer optical fibres is investigated and tested. Comparisons with a commercial UV based sensor demonstrate the ability of the visible based sensor to measure high concentrations over a range 27-127 mg/litre. A resolution of 5 mg/litre is also demonstrated for this sensor. 相似文献
932.
A. V. Solokhin S. L. Nazanskii V. S. Timofeev 《Theoretical Foundations of Chemical Engineering》2005,39(2):105-109
The evolution of the phase portrait for the dynamic system of open evaporation combined with a chemical reaction for a fixed liquid amount was studied as dependent on the rate constants of the reaction. A three-component azeotropic mixture whose vapor-liquid equilibrium diagram is characterized by two distillation regions was considered. The possibility of the open evaporation trajectory to transfer through the separatrix between the distillation regions was shown, as well as the possibility of implementing the principle of redistribution of the concentration fields due to chemical reactions occurring in reactive distillation columns.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 2, 2005, pp. 115–119.Original Russian Text Copyright © 2005 by Solokhin, Nazanskii, Timofeev. 相似文献
933.
A temperature sensor using a fiber-optic Fabry-Perot interferometer is described. A pseudo-heterodyne detection scheme is adopted to read the light phase difference in the Fabry-Perot interference output. A higher harmonic components comparison method is used to stabilize the system and to increase detection linearity. This system realizes not only highly sensitive temperature sensing with good linearity and minimal adjusting error, but also application to the sensing of other physical quantities such as vibrations. Additionally, the signal-to-noise ratio and distortion of the detected signal are investigated as functions of fiber end reflectivity. These results will be useful in designing a high performance fiber-optic Fabry-Perot thermometer. 相似文献
934.
An assessment is made of the technical contents of flight-vehicle structures curricula at 41 U.S. universities with accredited aerospace engineering programs. The assessment is based on the technical needs for the new and projected aeronautical and space systems as well as on the likely characteristics of the aerospace engineering work environment. A number of deficiencies and areas of concern are identified and recommendations are presented for enhancing the effectiveness of flight-vehicle structures education. A number of government supported programs that can help aerospace engineering education are listed in the appendix. 相似文献
935.
A novel moment-based m parameter estimator using noisy channel samples is derived. This estimator is simpler than known estimators. Numerical results are presented to demonstrate that, under some practical fading conditions, it outperforms previous estimators. 相似文献
936.
Y. Rey-Tauriac J. Badoc B. Reynard R.A. Bianchi D. Lachenal A. Bravaix 《Microelectronics Reliability》2005,45(9-11):1349
This paper presents results of reliability investigation of 20 V N-Drift MOS transistor in 0.13 μm CMOS technology. Due to high performances required for CMOS applications, adding high voltage devices becomes a big challenge to guarantee the reliability criteria. In this context, new reliability approaches are needed. Safe Operating Area are defined for switch, Vds limited and Vgs limited applications in order to improve circuit designs. For Vds limited applications, deep doping dose effects in drift area are investigated in correlation to lifetime evaluations based on device parameter shifts under hot carrier stressing. To further determine the amount and locations of hot carriers injections, accurate 2D technological and electrical simulations are performed and permit to select the best compromise between performance and reliability for N-Drift MOS transistor. 相似文献
937.
N. V. Vostokov Yu. N. Drozdov Z. F. Krasil’nik O. A. Kuznetsov A. V. Novikov V. A. Perevoshchikov M. V. Shaleev 《Russian Microelectronics》2005,34(4):203-209
The results are presented of the fabrication of strain-relaxed graded Si1 − x
Gex/Si(001) buffer layers with a maximum Ge fraction of about 0.25 that have a low density of threading dislocations (<106 cm−2) and low surface roughness. The buffer layers are grown by atmospheric-pressure hydride CVD. It is found that chemical mechanical polishing can reduce their surface roughness to a level comparable with that of the original Si(001) substrates. It is shown that the polished buffer layers can serve as substrates for MBE-grown SiGe/Si heterostructures.__________Translated from Mikroelektronika, Vol. 34, No. 4, 2005, pp. 243–250.Original Russian Text Copyright © 2005 by Vostokov, Drozdov, Krasil’nik, Kuznetsov, Novikov, Perevoshchikov, Shaleev. 相似文献
938.
What if every public space and surface were transformed into an interactive experience - capturing our movements, gestures, sounds and actions and using these to produce new sounds, images, text and actions? Bus stops could come alive and talk back, advertisements could look back at you and talk to you and public park robotic devices could play games with you. Will public places eventually become our social barometer as well as director? Will billboards display the populace's discourse? The author look at some special streets in France where the city is literally alive with art and explores what it might mean for us to live in a world of artistic interactivity. 相似文献
939.
M. M. Stadnyk 《Materials Science》2007,43(6):764-768
We deduce the theoretical formula taking into account the influence of biaxial loading of a plate weakened by a crack on the
stress intensity factor K
I. This enables us to compute the characteristic of crack resistance K
c according to the known boundary forces.
__________
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 6, pp. 14–16, November–December, 2007. 相似文献
940.
This paper considers the axisymmetric steady flow driven by exact counter rotation of two co-axial disks of finite radius.
At the edges of the rotating disks one of three conditions is (typically) imposed: (i) zero velocity, corresponding to a stationary,
impermeable, cylindrical shroud (ii) zero normal velocity and zero tangential fluid traction, corresponding to a (confined)
free surface and (iii) an edge constraint that is consistent with a similarity solution of von Kármán form. The similarity
solution is valid in an infinite geometry and possesses a pitchfork bifurcation that breaks the midplane symmetry at a critical
Reynolds number. In this paper, similar bifurcations of the global (finite-domain) flow are sought and comparisons are made
between the resulting bifurcation structure and that found for the similarity solution. The aim is to assess the validity
of the nonlinear similarity solutions in finite domains and to explore the sensitivity of the solution structure to edge conditions
that are implicitly neglected when assuming a self-similar flow. It is found that, whilst the symmetric similarity solution
can be quantitatively useful for a range of boundary conditions, the bifurcated structure of the finite-domain flow is rather
different for each boundary condition and bears little resemblance to the self-similar flow. 相似文献