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971.
Several methods using linear predictionz-transformation and autoregression have been applied to FTIR spectral analysis to reduce noise and improve resolution of an emission spectrum obtained from the truncated interferogram. 相似文献
972.
研究了用控制电位库仑法测定银、砷、汞、铜单元素标准溶液(1000ug/mL)中离子的含量,进行了控制电位、支持电解质种类等条件的选择,使得测定背景电流小,测定精度优于0.1%,并对样品进行了均匀性、稳定性检验。 相似文献
973.
通过分析询问域大小对底片乳剂颗粒产生的散斑噪声及其散斑噪声对干涉条纹识别的影响,推导出了询问域大小的选择与被测粒子位移量之间的关系,并详细讨论和分析了询问域的大小对所能探测的粒子位移量最大值的限止,以及合理选择询问域大小的依据. 相似文献
974.
研究了单模激光中的倍增噪声和饱和效应,导出了定态激光强度的平均值和归一化方差.同实验值相比较,理论与实验在阈值附近符合得很好.而在远高于阈值时,含有饱和效应的激光模型能更好地描述实际应用中的激光. 相似文献
975.
Wenlei Shan Yoshihisa Irimajiri Shengcai Shi Takeshi Manabe 《International Journal of Infrared and Millimeter Waves》2004,25(2):383-391
A fitting method is presented here for the accurate characterization of the IF noise contribution of a sub-millimeter SIS receiver. By fitting the mixer's IF output power response and junction's IV curve of an SIS mixer without LO pumping, we can obtain the IF noise contribution, the physical temperature of the isolator connected just behind the SIS mixer, the output mismatching of the mixer, and the total gain of the IF chain. Differing from a conventional method, which only uses the normal-state (linear) branch of the junction's IV curve, the method proposed here also includes the nonlinear portion around the gap voltage. The dynamic resistance in this portion is varied dramatically, providing us a good probe to characterize the output mismatching of the mixer, as well as other parameters. 相似文献
976.
977.
Hidemi Tsuchida 《Optical Review》1996,3(5):309-311
Frequency doubling of a Ti:sapphire laser with a KNbO3 crystal has been used to generate wavelength tunable amplitude-squeezed lights in the second harmonic mode. The crystal is placed in an enhancement cavity designed to resonate only the fundamental mode, and the phase matching condition is achieved by changing the crystal temperature. Noise reduction of 1.8–2.0 dB below the shot noise level is observed between 427.28 and 433.76 nm. 相似文献
978.
We consider the stochastic dynamics of an array of two closely spaced atomic force microscope cantilevers in a viscous fluid for use as a possible biomolecule sensor. The cantilevers are not driven externally, as is common in applications of atomic force microscopy, and we explore the stochastic cantilever dynamics due to the constant buffeting of fluid particles by Brownian motion. The stochastic dynamics of two adjacent cantilevers are correlated due to long range effects of the viscous fluid. Using a recently proposed thermodynamic approach the hydrodynamic correlations are quantified for precise experimental conditions through deterministic numerical simulations. Results are presented for an array of two readily available atomic force microscope cantilevers. It is shown that the force on a cantilever due to the fluid correlations with an adjacent cantilever is more than 3 times smaller than the Brownian force on an individual cantilever. Our results indicate that measurements of the correlations in the displacement of an array of atomic force microscopes can detect piconewton forces with microsecond time resolution. 相似文献
979.
M. Rudolph A. Destexhe 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(1):125-132
Systems driven by Poisson-distributed quantal inputs can be described as
“shot noise” stochastic processes. This formalism can apply to neurons
which receive a large number of Poisson-distributed synaptic inputs of similar
quantal size. However, the presence of temporal correlations between these
inputs destroys their quantal nature, and such systems can no longer be
described by classical shot noise processes. Here, we show that explicit
expressions for various statistical properties, such as the amplitude
distribution and the power spectral density, can be deduced and investigated
as functions of the correlation between input channels. The monotonic behavior
of these expressions allows an one-to-one relation between temporal
correlations and the statistics of fluctuations. Multi-channel shot noise
processes, therefore, open a way to deduce correlations in input patterns by
analyzing fluctuations in experimental systems. We discuss applications such
as detecting correlations in networks of neurons from intracellular recordings
of single neurons. 相似文献
980.
P. Lougovski H. Walther E. Solano 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(3):423-426
We present a method of measuring expectation values of quadrature
moments of a multimode field through two-level probe
“homodyning”. Our approach is based on an integral transform
formalism of measurable probe observables, where analytically
derived kernels unravel efficiently the required field information
at zero interaction time, minimizing decoherence effects. The
proposed scheme is suitable for fields that, while inaccessible to
a direct measurement, enjoy one and two-photon Jaynes-Cummings
interactions with a two-level probe, like spin, phonon, or cavity
fields. Available data from previous experiments are used to
confirm our predictions. 相似文献