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1.
Randall D. Campbell 《Experimental Astronomy》2002,14(1):57-60
Keck's Long Wavelength Spectrometer (LWS), is the facility instrument used for imaging and spectroscopy in the wavelength
range of 3–28 μm at the Keck Observatory. LWS uses an 128 × 128 Si:As blocked impurity band (BIB) array manufactured by the
Boeing Corporation. This paper discusses the method used for optimizing the detector's operating parameters at a temperature
of 8.5 K and bias voltage of 1.2 V. A process for characterizing detective quantum efficiency of BIB detectors is also presented.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
初至折射波静校正技术在复杂探区地震数据处理中的应用 总被引：1，自引：0，他引：1
山区及黄土塬地区近地表结构复杂，地形起伏大、低降速带横向变化剧烈，地震资料处理中的静校正难度加大。长波长静校正容易引起构造形态畸变，短波长静校正影响地震剖面信噪比。针对此类问题，从长波长静校正问题及短波长地表非一致性问题分析入手，提出部分炮检距叠加识别长波长静校正技术及分段统计逼近地表非一致性校正技术。该技术在复杂地表区与其它相关技术综合应用，可有效解决长、短波长静校正问题。 相似文献
3.
For any specific wind speed, waves grow in period, height and length as a function of the wind duration and fetch until maximum values are reached, at which point the waves are considered to be fully developed. Although equations and nomograms exist to predict the parameters of developing waves for shorter fetch or duration conditions at different wind speeds, these either do not incorporate important variables such as the air and water temperature, or do not consider the combined effect of fetch and duration. Here, the wind conditions required for a fully developed sea are calculated from maximum wave heights as determined from the wind speed, together with a published growth law based on the friction velocity. This allows the parameters of developing waves to be estimated for any combination of wind velocity, fetch and duration, while also taking account of atmospheric conditions and water properties. 相似文献
4.
在发现类星体的方法中,最有效的４ 种方法是：颜色方法,无缝光谱方法,射电方法和Ｘ射线方法。覆盖的波段为：射电波段,光学波段和Ｘ 射线波段。我们将４ 种方法联合在一起,应用于４ 个ＵＫＳｃｈｍｉｄｔ 天区。其目的是尽量减少选择效应,建立更完备的类星体巡天样本。本工作从１００２ 天区入手。已完成了Ｘ 射线选和部分光学选的分光观测工作。发现了一颗Ｂ＝ １５ ．０ 的亮类星体和一个Ｓｅｙｆｅｒｔ 对,其强Ｘ 射线辐射,是迄今首次观测到的。 相似文献
5.
熔融制样波长色散X射线荧光光谱法测定白云石中钙镁硅铁铝 总被引：4，自引：3，他引：1
白云石属碳酸盐矿物,应用熔融制样X射线荧光光谱法测定其中主次量组分钙、镁、硅、铁、铝时,由于白云石灼烧减量大,在试料片制备过程中,如果以干基试料制备试料片,除灼烧减量外还有少量其他组分被分解出的大量CO2带走,导致试料损失,测定结果偏低;如果以灼烧基试料制备试料片,由于灼烧后的试料极易吸收空气中的水分和CO2,同样使测定结果偏低。基于质量守恒原理,本文直接以灼烧减量测量后的灼烧基试料质量作为试料量(即灼烧减量测定所称量的干基试料量扣除灼烧减量的量),以四硼酸锂为熔剂,5%碘化铵溶液为脱模剂,试料与熔剂的稀释比为1:10,于1050℃熔融15 min以上制备的试料片透彻、玻璃化程度高。以白云石标准物质和标准样品作为标准试料,制作各组分的标准曲线的相关系数在0.9940~0.9994之间;方法检出限为0.011%~0.48%;标准物质和标准样品的测定值与认定值基本一致,各组分的相对标准偏差(RSD,n=11)在0.5%~1.7%之间,方法具有较好的重现性。本方法以1050℃灼烧后的试样作为试料制备XRF分析样片,最大限度地降低了灼烧减量因素(空气中的水分和CO2)对测定结果的影响,适用于白云石及其煅烧物中钙、镁、硅、铁、铝等组分的同时测定。 相似文献
6.
PAULJ.GEMPERLINE 《地理学报(英文版)》1989,(3)
One of the major application areas of factor analysis, multivariate calibration and quantitation, is coveredin this review. The algorithms, methodologies and applications covered include principal componentregression, target transformation factor analysis, singular value decomposition and rank annihilationfactor analysis. Many important areas of research having relevance to multivariate calibration andquantitation problems are also covered in this review, including background correction, measurementerror, rank determination, cross-validation, figures of merit, detection of invalid samples, experimentaldesign, sample selection, statistical inference and wavelength selection. 相似文献
7.
We consider the problem of resolving the total luminescence spectra of two-component mixtures.Non-negativity of the constituent spectra is commonly used as a criterion to accomplish this resolution,but its application seldom leads to unique answers. Sometimes, the condition must be relaxed because nosolution satisfying non-negativity exists. In these cases judgments must be made concerning which partsof the spectra will be allowed to go negative and by how much. The wavelength component vectorgramn (WCV) is presented here as a tool for assisting theexperimenter in making these judgments. Even when non-negative resolutions exist, it may happen thatresolutions with slight negative elements will more closely match the spectra of the pure constituents.The WCV can also be used as a tool for detecting these cases. The methodology is illustrated with realdata from a two-component mixture. 相似文献
8.
A portable remote methane detector using an InGaAsP DFB laser 总被引：1，自引：0，他引：1
A portable remote methane detector based on infrared-absorption spectroscopy using an InGaAsP distributed-feedback laser is described. This equipment transmits a laser beam and detects a fraction of the backscatter reflected from the target. From this, the detector thereby measures the integrated methane concentration between the detector and the target. The equipment operator can easily detect methane clouds at a distance by hand-scanning the laser beam. To achieve a high sensitivity of detection, wavelength-modulation spectroscopy is applied to the infrared-absorption measurement for methane. The wavelength of the light source is modulated at a frequency of 10 kHz, and the center wavelength is stabilized at the center of the 23 band R(3) line of methane (1.65372 m). When used with typical targets at distances up to 10 m, the detector has a detection limit of less than 5 ppm-m. To the best of the authors knowledge, the detector is the only hand-held product capable of remote methane detection. Recently, this novel equipment was commercially introduced into the Japanese market as a product named the Portable Remote Methane Detector (PRMD). Some PRMD units were in research use for detecting methane emissions from garbage landfills, although the PRMD was mainly developed for remote detection of leaks from natural gas pipelines. The author expects that the PRMD could become the standard equipment for field measurements of methane emissions from land. 相似文献
9.
频率为3~30 kHz的甚低频（VLF,Very Low Frequency）电磁波具有波长长、传播距离远的特点,能够沿地面-低电离层波导进行传播,在通信、导航等许多领域都被广泛应用.基于波导模理论的长波传播模型（LWPC,Long-Wavelength Propagation Capability）能够用于计算甚低频波的传播路径及幅度,进而研究耀斑、磁暴、地震等事件对电离层的扰动.本文利用国际电离层参考模型（IRI,International Reference Ionosphere）对LWPC中电子密度和碰撞频率进行改进,并将模拟结果与武汉大学VLF接收机实际观测到的NWC （North West Cape）台站信号幅度进行比较分析,结果表明改进后LWPC模型得到的幅度及变化趋势与实际值更加接近.LWPC模型给出的电子密度与IRI模型得到的电子密度在日间基本一致,但是在夜间存在差异,造成夜间部分区域NWC台站信号幅度的差异性,验证了电离层电子密度对于VLF信号传播具有的重要影响.传播路径上的晨昏变化也可以引起VLF信号幅度分布的突变,在日出和日落时间段内存在明显的过渡区域.基于IRI模型的LWPC,改善了VLF电波传播过程的预测分析效果,提供了一种长波导航通信质量的评估方法. 相似文献
10.
短波红外光谱技术在矽卡岩型矿床中的应用——以鄂东南铜绿山铜铁金矿床为例 总被引：2，自引：2，他引：0
铜绿山铜铁金矿床是长江中下游铜铁多金属成矿带最重要的矽卡岩型矿床之一,矿床的形成与铜绿山石英闪长岩株体密切相关,矿体主要沿北北东向断裂产于石英闪长岩与大理岩/白云质大理岩的接触带,形成钙-镁复合型矽卡岩铜多金属矿化。围岩蚀变由致矿岩体到接触-蚀变矿化中心为:绢云母-绿泥石-钾化带、高岭石-绿泥石-弱矽卡岩化带、皂石-绿泥石-强矽卡岩化带。蚀变矿化期次可分为岩浆-热液期和表生期,其中,岩浆-热液期可分为矽卡岩阶段、退化蚀变阶段、氧化物阶段、硫化物阶段和碳酸盐阶段。绿泥石是钻孔岩芯中出现最多且分布最为广泛的蚀变矿物之一。经短波红外光谱(SWIR)研究发现,从蚀变矿化中心到外围,绿泥石出现由铁绿泥石/铁镁绿泥石逐渐转变为镁绿泥石,且绿泥石Fe-OH特征吸收峰位值(Pos2250)显示出从高值变为低值的趋势。结合其他蚀变矿物的空间分布特征,文章提出绿泥石的高Fe-OH特征吸收峰位值(Pos22502253 nm)与金云母、蛇纹石、绿帘石、皂石和高岭石的大量出现,对指示铜绿山矽卡岩型矿床的矿化中心具有一定的作用。 相似文献