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Nd doped fluoroapatites SrxCa5−x(PO4)3F(SxC5−xPF, X = 0, 1, 2, 3, 4, and 5) single crystals have been grown by the Czochralski technique. Their polarized absorption and emission spectra have been recorded at room temperature and used to calculate the absorption and stimulated emission cross sections. Broadening of the absorption and emission bands is observed for Nd3+ in the solid solutions SPF-CPF compared to Nd3+ in CPF or SPF. 1% Nd:SxC5−xPF, X = 0, 2, 3, 4, and 5, laser rods have been tested in a cavity longitudinally pumped by a 1 W AlGaAs laser diode and compared to Nd:YAG and Nd:YVO4 rods. All fluoroapatites exhibit very good laser performance with low thresholds and high slope efficiencies, higher than in the case of YAG and equal to the YVO4 samples. The dependance of the laser output power versus the diode temperature has also been measured for all materials. The laser output was found to be as sensitive to the diode temperature fluctuations for fluoroapatites as for YAG. 相似文献
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中频变频器UFV故障探析 总被引:2,自引:1,他引:1
本文对中频变频器的UFV故障进行了系统试验和原因分析,并对UFV故障的关键因素进行了详细探析。 相似文献
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Latent or sub-clinical hepatic encephalopathy is a recognized complication of cirrhosis and is thought to represent one end of the spectrum of neuropsychiatric impairment, which occurrs as a result of portal-systemic shunting. We studied the psychometric, analyzed electroencephalography (EEG), and venous blood ammonia responses to an oral glutamine challenge in 17 patients with cirrhosis and in 4 normal controls. The cirrhotics were attending for liver transplant assessment and had no clinical evidence of hepatic encephalopathy. The oral glutamine challenge was repeated following liver transplantation. Five of sixteen patients (31%) showed impaired performance on at least one of the baseline psychometric tests. There was a correlation between fasting venous ammonia and choice reaction time (r = .7, P < .01). Following glutamine challenge there was a significant increase in blood ammonia from a mean fasting value ranging between 58 micromol/L to 120 micromol/L (P < .01), between significant prolongation of reaction times of 387 ms to 428 ms (P < .01), and an increase in mean EEG amplitude between 68.5 microV to 78.6 microV (P < .001). Four normal controls who were challenged with glutamine and 6 cirrhotic patients who were challenged with water showed no change in any of these parameters. Following orthotopic liver transplantation (OLT) the eight patients studied had normal baseline psychomotor performance with significant improvements in digit symbol, digit span, information processing, number connection tests (P < .05), and reaction time (P < .005). Posttransplantation, there were no significant changes in blood ammonia, analyzed EEG, or choice reaction time in response to oral glutamine challenge (six patients). We conclude that short lived changes in blood ammonia (in cirrhotics) can cause significant impairment of sensitive tests of brain function and that psychometric performance is improved following OLT. 相似文献
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Borel S. Levadoux D.P. Alouges F. 《Antennas and Propagation, IEEE Transactions on》2005,53(9):2995-3004
We present a new boundary integral equation dedicated to the solution of the boundary problem of a perfectly electrically conducting surface for the harmonic Maxwell equations in unbounded domains. Any solution of the harmonic Maxwell equations is represented as the electromagnetic field generated by a combination of electric and magnetic potentials. These potentials are those appearing in the classical combined field integral equation (CFIE), but their coupling is realized by an operator Y/spl tilde//sup +/ instead of a coefficient. Therefore, the integral equation obtained can be viewed as a generalization of the CFIE. In this paper, we propose an explicit construction of the coupling operator Y/spl tilde//sup +/ which is designed to approximate the exterior admittance operator of the scattering obstacle. A local approximation by the admittance operator of the tangential plane seems to be relevant thanks to the localization effects related to high-frequency phenomena. The provided numerical simulations show that this formulation leads to linear systems that are better conditioned compared to more classical integral equations, which speeds up the resolution when solved with iterative techniques. 相似文献
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Attention deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) are both disorders of childhood and adolescence that all too frequently extend into adulthood. But just what is the relationship between these two disorders? This study explores the overlap between these two disorders as they relate to juvenile delinquency; both are significant risk factors for the development of antisocial behavior. But there is more significance to the presence or absence of ADHD or CD in later antisocial behavior. Higher levels of defiant and/or aggressive behavior lead to antisocial acts as compared with lower levels of defiance and antisocial acts. Boys diagnosed with ADHD have higher felony rates than normal control boys, yet ADHD is not nearly as strong a predictor of offending behavior as is CD in study subjects. The presence of both CD and ADHD contributes to illegal behavior, and it is likely that early intervention in both disorders will reduce the prevalence of antisocial behavior. 相似文献