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111.
Laser-induced fluorescence is used to characterize the axial velocity and temperature field at the exit plane of a low-power
helium arcjet. Two cases were examined, one in which the mass-flow rate was changed at a constant current, and the other where
the current was changed at a constant mass-flow rate. At constant mass-flow rate, the velocity scales with the increase in
power. At constant current, a higher specific energy results in an unexpected lower mean exit velocity. The temperature profiles
show that the nozzle-wall temperature is greater than the mean exit temperature. Along the axis of the arcjet, these measurements
indicate the presence of a shock less than one nozzle diameter downstream of the exit.
Received: 10 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +1-650-723-1748, E-mail: qwalker@stanford.edu 相似文献
112.
The reaction shown is presumed to be a new [3,3]-sigmatropic rearrangement involving an O-arylsulfoxonium species or related sulfurane. It allows a sulfoxide and a phenol to be joined and rearranged in one operation at or below room temperature, coupling an aromatic to a quaternary carbon and creating benzofurans or articulated dihydrobenzofurans in a number of examples. 相似文献
113.
M. Odlyha R. M. Walker W. H. Liddell 《Journal of Thermal Analysis and Calorimetry》1993,40(1):285-302
Prior to treatment, letters dating from 1665–66 were characterised using SEM, FTIR, ESCA or XPS, TG, TMA and DLTMA. All three papers were similar in composition and were basically cellulosic materials. Two which had been sent from Lisbon contained trace amounts of Fe and Cu; these impurities were also present in a letter sent from Dublin. All three letters had been written with iron gall ink. The letter from Dublin had an additional feature in the ink in the form of small bright specks of mica. The papers were examined after conservation treatment using the above same techniques in an attempt both to determine and quantify any changes which had occurred during the treatment process. Scanning electron micrographs showed that propounced changes had occurred to the surfaces of the treated papers. With XPS it was possible to measure the change in the surface composition of the papers which occurred on treatment. It was also found that the treatment reduced the thermal stability of the papers in all three cases. 相似文献
114.
M. Convery W. L. Davis K. DelSignore T. L. Jenkins E. Kangas M. Knepley K. L. Kowalski C. C. Taylor C. H. Wang S. H. Oh W. D. Walker P. L. Colestock B. Hanna M. A. Martens J. M. Streets R. C. Ball H. R. Gustafson L. W. Jones M. J. Longo J. D. Bjorken N. Morgan C. Pruneau 《Il Nuovo Cimento C》1996,19(6):1045-1049
Summary A small experiment, ?MiniMax?, has been set up in the C0 intersection region of the Fermilab Tevatron to seek evidence for
disoriented chiral condensates and to study other forward physics phenomena. The experiment consists of a proportional wire
chamber telescope accompanied by scintillation (trigger) counters, a lead converter, and followed by an electromagnetic calorimeter.
The solid angle accepted is a cone centered at pseudorapidity (η) of 4.1 and of radius (in η-ϕ space) of about 0.6. Over 2.5
million events thus far have demonstrated the successful operation of the apparatus, however to date the analysis has not
progressed sufficiently to permit any conclusions concerning disoriented chiral condensates.
presented byL. W. Jones
Paper presented at the Special Session on very high-energy cosmic-ray interactions (superfamilies) of the XXIV International
Cosmic-Ray Conference, Rome, August 28–September 8, 1995. 相似文献
115.
Single axial mode pumping and external mirror operation of a pulsed spin-flip Raman laser at 10.6 μm
By the addition of an external cavity to a single axial mode, TEA CO2 laser pumped, In Sb spin-flip Raman laser, a tenfold increase in first Stokes output and a twenty-five fold increase in second Stokes and anti-Stokes outputs has been observed. 相似文献
116.
The crossing of an octupole band by a rotation-aligned two-quasiparticle band has been observed in detail in 162Dy. Both the yrast and yrare states are identified from the band heads (I =2 and I = 5) to high spin (I ~ 14), with band crossing in both the even-spin and odd-spin sequences. 相似文献
117.
118.
119.
Typically encountered proton-decoupled spectra of [U-13C]-labeled molecules or proton-coupled spectra of natural abundance or singly labeled molecules contain many nuclei which satisfy the weak coupling approximation. The spectra of such nuclei are frequently highly asymmetric and often appear to exhibit the skewed intensity distribution characteristic of strongly coupled spins. Analysis of typical cases indicates that such effects arise in the presence of at least one moderately strong coupling interaction in the spin system (Jδν ~ 1/3), and the apparent intensity asymmetry reflects small differences in the spacing of unresolved components of the observed resonance. This effect is analogous to the case of ‘virtual coupling’ in which weakly coupled spins cannot be analyzed as first order spectra; however; the ABX spin system which generally serves as a model for such systems does not predict the existence of spectral asymmetry for the X resonances. Prediction of this asymmetry requires a spin system of at least four spins with at least ABMX complexity, and can be treated generally using the effective Hamiltonian approach of Poeple and Schaefer. 相似文献
120.
Dominating proton structure has been identified in the Kπ=3+ band of 168Yb, contrasting with neutron structure in the corresponding band of 172Yb. A region of low-lying Kπ=3+ bands is now established, with N=98?104, Z=68?72. For all stable nuclei in this region, the IπK=4+3 state is excited by inelastic deutron scattering. 相似文献