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991.
本文介绍子带峰值能量检测方法及其在被动声纳显示和检测中的应用[2-4],同时提出了波束域宽带峰值能量检测算法。新的波束域算法是在已有波束形成的基础上进行处理,不需对原系统进行较大的修改。通过波束域宽带峰值能量检测处理,可以改善声纳显示效果,更加清晰地显示目标方位。相对于高分辨率波束形成算法,两种峰值能量检测算法的运算量都比较低,具有一定的工程应用前景。通过计算机仿真和实测数据处理,验证了所述两种峰值能量算法在提高显示清晰度,减小测向模糊度方面的优点。 相似文献
992.
993.
994.
A new anthracene derivative bearing two phenylboronic acid groups at the 1,8-positions was prepared and its binding properties towards sorbitol, xylitol, fructose, glucose and galactose have been studied using fluorescence analysis. 相似文献
995.
Colleen C. Mitchell 《Journal of Mathematical Analysis and Applications》2005,309(2):567-582
We explore the precision of neural timing in a model neural system with n identical input neurons whose firing time in response to stimulation is chosen from a density f. These input neurons stimulate a target cell which fires when it receives m hits within ? msec. We prove that the density of the firing time of the target cell converges as ?→0 to the input density f raised to the mth and normalized. We give conditions for convergence of the density in L1, pointwise, and uniformly as well as conditions for the convergence of the standard deviations. 相似文献
996.
Diana DiBerardino Robert J. Rafac Steven Boone Vladislav P. Gerginov Carol E. Tanner 《Optics Communications》2002,210(3-6):233-243
This paper describes the position-sensitive light-collection system that we use in our fast-beam laser experiments. The collection system consists of fiber-optic bundles whose facets are arranged to accept light emitted from a beam of fluorescent atoms. The flexibility of the fiber bundles allows their use in scanning collection systems with precise position sensitivity. We describe calculations of geometrical collection efficiency using a numerical integration scheme and compare the results with measurements. We also compare the collection efficiencies of the different fiber bundle arrangements that we used as our apparatus evolved with the implementation of various improvements. 相似文献
997.
998.
Influence of laser intensity in second-harmonic detection with tunable diode laser multi-pass absorption spectroscopy 总被引:6,自引:0,他引:6 下载免费PDF全文
Tunable diode laser absorption spectroscopy (TDLAS) has been widely employed in atmospheric trace gases detection. The ratio of the second-harmonic signal to the intensity of laser beam incident to the multi-pass cell is proved to be proportional to the product of the path length and the gas concentration under any condition. A new calibration method based on this relation in TDLAS system for the measurement of trace gas concentration is proposed for the first time. The detection limit and the sensitivity of the system are below 110 and 31ppbv (parts-per-billion in volume), respectively. 相似文献
999.
Shielding against noise interfering with quantitation of insect infestations by acoustic detection systems in grain elevators 总被引:1,自引:0,他引:1
Acoustic devices used to detect hidden insect infestations must be shielded from noise in most practical applications. One device developed specifically for use in a noisy environment, the Acoustic Location ‘Fingerprinting’ Insect Detector (ALFID), counts the numbers of insects present in grain samples from shipments being graded for export at commercial grain elevators. This report considers the performance of ALFID's noise-shielding components, which include an enclosure for passive reduction of ambient noise, and an electronic system for active detection and masking of sounds originating outside the grain sample container. Sound pressure levels (SPLs) of ambient noise are reduced inside the enclosure by 60–90 dB at frequencies between 1 and 10 kHz, with a reduction of ~6.5 dB per octave (frequency doubling). The active noise-masking system protects ALFID from loud ambient sounds not sufficiently attenuated by the enclosure. If the output from one of four sensors mounted on the outside of the grain sample container rises above a preset amplitude threshold, a signal is triggered that inhibits acquisition of insect sound data from sensors inside the container. In tests of the complete ALFID system at a grain elevator with ambient noise of 73 ± W dB re 20 μPa SPL, the mean rate of noise-mask triggering was 5.5 s−1, inhibiting acquisition of insect sounds for only 3.9% of the total testing period. This level of performance is sufficient to enable successful operation of ALFID under such noise conditions. 相似文献
1000.
离子色谱电导检测法测定酒中的有机酸和无机阴离子 总被引:7,自引:0,他引:7
采用淋洗液发生器-抑制电导检测法,同时分离和检测16种无机阴离子和低分子量有机酸,建立了用亲水性阴离子交换分离柱,KOH为淋洗液等浓度泵作梯度淋洗的离子色谱分离方法. 该方法具有良好的重现性、线性关系. 除马来酸外,所有被测离子的检测限都在0.16 mg/L以下. 方法用于测定4种酒样品的分析,结果满意.样品测定的回收率在93.52%到116.08%之间,除富马酸外其它RSD都小于3.8%. 相似文献