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991.
摘要:《工程地质学报》(简称《学报》)经过17年的不断发展壮大,目前各项指标均取得了长足的进步。为了对《学报》有一个明确的发展定位,有必要学报近年来的各项指标进行科学的统计评估。本文主要依据《学报》近年的相关数据进行统计,对《学报》的影响因子等各项综合指标等进行系统分析,总结出学近年来的发展规律,找出不足,为进一步提升学报学术质量提供一个科学的根据。  相似文献   
992.
研究了微型激光扩束镜准超光滑表面的加工工艺。分析了机床速度、压力、抛光粉、工作温度、抛光模等对高质量表面的影响。选定了一系列的工艺参数,大幅度地提高了产品的合格率。  相似文献   
993.
This paper presents a stability analysis of an oscillating body subjected to fluid forces located in a transient incompressible viscous flow. If the body is supported by elastic springs, oscillation will begin. If the characteristic period of the body and the excited oscillating period due to fluid forces match each other, resonance can occur. Stability analysis is therefore needed to determine the nonlinear behavior of the body. This paper presents an analysis of the changing stability of bodies by the numerical computation. To implement the computation, the motion of fluid around a body is expressed by the Navier–Stokes equation described in the arbitrary Lagrangian–Eulerian form. The fluid influence on the body is discretized by the finite element method based on a mixed interpolation by the bubble function in space. The motion of the body is assumed to be expressed by the equations of motion. To evaluate stability, stability function is defined by the total energy of the oscillating body. The stability is judged according to a stability index, obtained by the use of the automatic differentiation (AD) of the stability function. AD is a derivative computation method that gives high accuracy. By the use of AD, the second‐order derivative matrix, which is needed to compute the stability index, can be obtained exactly. For the numerical studies, analyses of one degree of freedom and two degrees of freedom (2DOF) for a circular cylinder and 2DOF for a rectangular cylinder are carried out. A combination of a cylinder and supporting elastic spring can produce stable, neutral and unstable states. It is shown that the stability of the cylinder can be determined by the stability index. This paper shows new possibilities for stability analysis of bodies located in a fluid flow. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
994.
ANewResonatorWithANon─misalignedFourMirorReflectorAndItsEfectOnBeamQualityImprovementOfHighAveragePowerNd:YAGLasersC.M.Zhao,G...  相似文献   
995.
The degradation of beam quality in large-core fiber is investigated experimentally. It is found that the output beam quality factor M2 is a compound tanh function ofthe fiber lengths and misalignment launch results that the beam quality degraded faster.  相似文献   
996.
唐万梅 《运筹与管理》2005,14(4):85-89,79
本文利用因子分析法分析比较了我国西部各地区的人口素质,分析了西部地区人口素质水平低的原因,同时对提高地区人口素质提出了建设性的意见。为政府在制定地区产业发展方向、确定地区经济走向时提供参考。  相似文献   
997.
A beam is described by its transverse power density distribution, its wavefront, and its transverse distribution of coherence. The beam propagation ratio, M2, is expressed as the square root of the sum of each of the three beam attributes. The shape of the power density distribution governs the diffraction of the beam. The stronger it is modulated, the higher the M2. In comparison to an non-aberrated beam, the M2 of a beam with an aberrated wavefront is increased. Similarly, the M2 of a partially coherent beam is higher than the one of a fully coherent one. A concise formula is derived. The components of M2 of a mixture of Hermite–Gaussian beams and of a spherically aberrated Gaussian beam are given as examples.  相似文献   
998.
当前中成药质量控制现状分析   总被引:6,自引:1,他引:5  
综述了当前中成药质量控制的现状,分析了中成药质量控制存在的问题及其今后的发展方向。  相似文献   
999.
The goal of this study was to determine if there are acoustical differences between male and female voices, and if there are, where exactly do these differences lie. Extended speech samples were used. The recorded readings of a text by 31 women and by 24 men were analyzed by means of the Long-term Spectrum (LTAS), extracting the amplitude values (in decibels) at intervals of 160 Hz over a range of 8 kHz. The results showed a significant difference between genders, as well as an interaction of gender and frequency level. The female voice showed greater levels of aspiration noise, located in the spectral regions corresponding to the third formant, which causes the female voice to have a more “breathy” quality than the male voice. The lower spectral tilt in the women's voices is another consequence of this presence of greater aspiration noise.  相似文献   
1000.
This paper uses a laboratory experiment to examine the effect of DSS use on the decision maker’s error patterns and decision quality. The DSS used in our experiments is the widely used Expert Choice (EC) implementation of the Analytic Hierarchy Process. Perhaps surprisingly, our experiments do not provide general support for the often tacit assumption that the use of a DSS such as EC improves decision quality. Rather, we find that, whereas a DSS can help decision makers develop a better understanding of the essence of a decision problem and can reduce logical error (especially if the information load is high), it is also susceptible to introducing accidental effects such as mechanical errors. In some cases, as in our study, the accidental errors may outweigh the benefits of using a DSS, leading to lower quality decisions.  相似文献   
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