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81.
S. M. Curry R. Cubeddu T. W. Hänsch 《Applied Physics A: Materials Science & Processing》1973,1(3):153-159
A novel scheme is proposed for stabilizing the intensity of a fluctuating laser source, using a partly saturated high gain
traveling wave laser amplifier with a nonsaturable absorber distributed in the amplifying medium. Calculations for homogeneously
broadened laser gain band in an adiabatic approximation are presented, which indicate that the stabilization factor can be
increased by several orders of magnitude with the help of the absorber. An experiment is reported in which a two-stage dye
laser amplifier with inserted attenuator, pumped by a nitrogen laser, is used to amplify and stabilize the intensity of an
ultra-narrowband repetitively pulsed dye laser. The output intensity changes by less than a factor of four when the input
is changed over three orders of magnitude.
Work supported by the U.S. Office of Naval Research, Contract No. N00014-67-A-0112-0071, and by a Grant from the Research
Development Fund, Stanford University.
On leave from the Laboratorio de Elettronica Quantistica del CNR di Milano, Milano, Italy. 相似文献
82.
Gabriele Cazzoli Rinaldo Cervellati David G. Lister Damiano Damiani Claudio Degli Esposti 《Journal of Molecular Spectroscopy》1983,101(1):94-103
Direct l doublet transitions have been observed for the 0110 state of the 35Cl12C14N and 37Cl12C14N isotopic species of cyanogen chloride and the 79Br12C14N and 81Br12C14N isotopic species of cyanogen bromide in the frequency range 4–22 GHz. The l-doubling constants (q0, q1, q2) and the asymmetry parameters (ηeQqz) of the halogen nuclear quadrupole coupling tensors have been derived. The constants q1 have been calculated form the vibrational force fields of Whiffen for the four cyanogen halides using the formulation of Watson. Agreement with the observed values is found to be 10% or better and for cyanogen fluoride and cyanogen chloride the isotopic shifts in q1 are also well predicted. 相似文献
83.
Pulses of 100 ps duration and peak power up to 100 kW are obtained with a dye laser pumped by an atmospheric pressure nitrogen laser of 0.5 ns duration. The shortening of the dye laser pulses is attributed to amplified spontaneous emission. 相似文献
84.
85.
86.
We introduce a sort of semilinear structure on subsets of the family of semigroups
defined on a metric space. The key step is the definition of the sum of two
semigroups, which is here achieved by means of the classical operator splitting
technique. No linearity assumption is required, since the whole construction is
in a metric space. 相似文献
87.
International safety standards recommend a limit below 30% variation in acoustic intensity for ultrasound therapy (UST) equipment. In view of this question, the purpose of this work was to evaluate the intensity of new UST equipment in the Brazilian market. An evaluation was performed of eight models manufactured by six different national manufacturers; under continuous and pulsed conditions, at frequencies of 1.0-3.0 MHz, for a total of 48 items of equipment. The intensities were analysed according to the technical standards IEC 601-2-5, in the range 0.01-3.0 Wcm(-2), using a radiation pressure scale UPM-DT-10 (Ohmic Instruments), previously calibrated. The results demonstrated that the models Sonacel, Sonacel plus, Sonacel III, Avatar I, and Sonamed I, although they were new (unused) presented calibration errors of over 30% in more than one intensity checked, and the models SONOPULSE, PRO-SEVEN and SONOMASTER ST. are within the standards proposed. The results show that industry must improve quality control on their production lines, as well as that there is a need for a supervising body at national level. Published by Elsevier Science B.V. 相似文献
88.
On the Control of the Friction Force 总被引:1,自引:1,他引:1
This paper tackles the problem of controlling the Coulomb friction force in order to achieve damping characteristics which can be advantageous in engineering applications, particularly in the area of vibration control, for example, vehicle suspensions, rotating machinery foundations or earthquake protection systems. The control schemes employed belong to the family of variable structure controllers (VSC), a class of robust control algorithms, namely sliding mode control (SMC) and switched state feedback (SSF). The schemes perform force tracking control, aiming at making the friction force track a reference force in order to reduce the acceleration experienced by a suspended mass. The plant investigated is a 2-degree of freedom system and in this study represents a quarter car. The controller performances are investigated both numerically and experimentally. 相似文献
89.
Art D. Bochevarov Edward Harder Thomas F. Hughes Jeremy R. Greenwood Dale A. Braden Dean M. Philipp David Rinaldo Mathew D. Halls Jing Zhang Richard A. Friesner 《International journal of quantum chemistry》2013,113(18):2110-2142
Jaguar is an ab initio quantum chemical program that specializes in fast electronic structure predictions for molecular systems of medium and large size. Jaguar focuses on computational methods with reasonable computational scaling with the size of the system, such as density functional theory (DFT) and local second‐order Møller–Plesset perturbation theory. The favorable scaling of the methods and the high efficiency of the program make it possible to conduct routine computations involving several thousand molecular orbitals. This performance is achieved through a utilization of the pseudospectral approximation and several levels of parallelization. The speed advantages are beneficial for applying Jaguar in biomolecular computational modeling. Additionally, owing to its superior wave function guess for transition‐metal‐containing systems, Jaguar finds applications in inorganic and bioinorganic chemistry. The emphasis on larger systems and transition metal elements paves the way toward developing Jaguar for its use in materials science modeling. The article describes the historical and new features of Jaguar, such as improved parallelization of many modules, innovations in ab initio pKa prediction, and new semiempirical corrections for nondynamic correlation errors in DFT. Jaguar applications in drug discovery, materials science, force field parameterization, and other areas of computational research are reviewed. Timing benchmarks and other results obtained from the most recent Jaguar code are provided. The article concludes with a discussion of challenges and directions for future development of the program. © 2013 Wiley Periodicals, Inc. 相似文献
90.
Francesca Leonelli Luisa Maria Migneco Alessio Valletta Rinaldo Marini Bettolo 《Molecules (Basel, Switzerland)》2021,26(9)
The scientific activity carried out over forty-five years on stemodane diterpenes and diterpenoids structure elucidation, biogenesis, biosynthesis, biological activity and biotransformations was reviewed. 相似文献