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111.
在室内水泥池,利用沙层自净养殖模式和直接铺沙养殖模式对不同规格的方斑东风螺(Babylonia areolata Link)进行了高密度养殖的研究。结果表明,沙层自净养殖模式养殖小螺、中螺、大螺组日均增重分别为0.031、0.088、0.098g/d,沙层NH4^+-N最高含量ω分别为1.3、2.1、3.1mg,/L,H2S最高含量ω分别为0.03、0.07、0.14mg/L.各规格组东风螺保持正常生长和活动,成活率92.9%以上;直接铺沙养殖模式养殖小螺、中螺、大螺日均增重分别为:0.023、0.051、0.068g/d.成活率分别为95.2%、86.7%、84.9%,沙层NH4^+-N最高含量ω达到13.7mg/L,H2S最高含量ω达到0.47mg/L,沙层底质恶化,东风螺活动异常、不摄食。可见,沙层自净养殖模式对方斑东风螺的生长、成活率、沙层水质控制效果显著,在一定程度上克服了直接铺沙养殖底质恶化问题。 相似文献
112.
Two optimization techniques ta predict a spatial variable from any number of related spatial variables are presented. The applicability of the two different methods for petroleum-resource assessment is tested in a mature oil province of the Midcontinent (USA). The information on petroleum productivity, usually not directly accessible, is related indirectly to geological, geophysical, petrographical, and other observable data. This paper presents two approaches based on construction of a multivariate spatial model from the available data to determine a relationship for prediction. In the first approach, the variables are combined into a spatial model by an algebraic map-comparison/integration technique. Optimal weights for the map comparison function are determined by the Nelder-Mead downhill simplex algorithm in multidimensions. Geologic knowledge is necessary to provide a first guess of weights to start the automatization, because the solution is not unique. In the second approach, active set optimization for linear prediction of the target under positivity constraints is applied. Here, the procedure seems to select one variable from each data type (structure, isopachous, and petrophysical) eliminating data redundancy. Automating the determination of optimum combinations of different variables by applying optimization techniques is a valuable extension of the algebraic map-comparison/integration approach to analyzing spatial data. Because of the capability of handling multivariate data sets and partial retention of geographical information, the approaches can be useful in mineral-resource exploration. 相似文献
113.
激光时间传递技术的进展 总被引:4,自引:0,他引:4
激光时间传递技术是通过激光脉冲在空间的传播来实现地面与卫星时钟或地球上远距离两地时钟的同步,它具有很高的准确度和稳定度。一些国家已经成功进行了激光时间传递的试验,结果证明利用激光进行时钟之间的同步是有效可行的。介绍国内外已有的激光时间传递试验的情况和结果,重点介绍美国地面与机载原子钟之间的激光时间比对,以及法国的LASSO(LAser Synchronization from Stationary Orbit)和T2L2(Time Transfer by Laser Link)计划。 相似文献
114.
GPS掩星技术和电离层反演 总被引:13,自引:6,他引:7
系统地介绍了GPS无线电掩星技术的发展现状、系统组成和一些关键技术;论述了利用GPS掩星数据进行电离层反演的理论、模型及相应的计算流程.并结合GPS/MET和CHAMP卫星的实测资料,计算了电子密度剖面,与用其他方法所得结果的对比表明.GPS掩星电离层观测具有精度高、覆盖范围大等特点;最后讨论了GPS掩星技术应用于地震前兆监测的机理和前景。 相似文献
115.
GRAN NILSSON 《地理学报(英文版)》1991,(6)
Comparison of methods is a technique often used for investigation of systematic errors of measurementmethods.As concerns the design and analysis of such comparisons,much variety of opinion and practiceexists.In one approach a few specimens are measured several times by different operators in differentlaboratories(reproducibility conditions)and in another approach several specimens are measured on oneor a few occasions by one operator in the same laboratory(repeatability conditions).In this paper amodel for the error structure of measurements is formulated and it is emphasized that one has todistinguish between two types of systematic errors:the first type depends only on the level of themeasured quantity and the second type is specific for the separate specimens.On the basis of this modelthe information which can be obtained from the different designs of method comparisons is discussed.A new approach for the analysis of method comparisons with many specimens is also proposed. 相似文献
116.
《The Professional geographer》1988,40(1):106-116
software reviews are in this article BMDP/PC CONCEPTS COMPUTERIZED ATLAS EVALUATION OF ALTERNATE PROPOSALS (EAP) EXTRA: EXPRESS TRANSIT ANALYSIS MATC CAD MOTORS TRANSPORTATION PACKAGE PCMAP: Thematic Mapping Software for the IBM Personal Computer, Version 2.3 PLACE TRANPLAN . US-ATLAS 相似文献
117.
M.-P. Ledru D.-D. Rousseau F.W. Cruz Jr. C. Riccomini I. Karmann L. Martin 《Quaternary Research》2005,64(3):444-450
A long terrestrial record, Colônia CO-3, from the Atlantic rainforest region in Brazil (23°52′S, 46°42′20 W, 900 m a.s.l.) registrates variations in the forest expansion during the last 100,000 yr. The 780-cm depth core was analyzed at 2-cm intervals and arboreal pollen frequencies were compared to nearby speleothem stable isotope records and neighboring marine records from the tropical Atlantic. To evaluate regional versus global climate forcing, our record was compared with Greenland and Antarctic ice-core records. These comparisons suggest that changes in temperature seen in polar latitudes relate to moisture changes: e.g., to changes in the length of the dry season, in tropical and subtropical latitudes during glacial as well as interglacial times. These climatic changes result from changes in the frequency of polar air incursions to these latitudes inducing a permanent cloud cover and precipitation. This is an important result that should help define paleoclimatic features in the Southern Hemisphere for the last glaciation. 相似文献
118.
Analysis of stomach contents of samples of clupeid fishes (Japanese anchovy, half-fin anchovy, zunas' scaled sardine, rednosed
glassnose and tapertail anchovy) collected from the catches of a 1982–1984 fishery resource survey showed they are zooplanktonivorous.
Similar food groups, such as copepoda. Chaetognatha, Amphipoda and Mysidacea were found in the stomach. Dietary similarity
coefficients were studied to evaluate the degree of similarity in the dietary species-pairs. Seasonal variation is discussed.
Contribution No.2050 from the Institute of Oceanology, Academia Sinica. 相似文献
119.
采用双压力室三轴仪对粉煤灰试样进行了单线法湿陷试验,研究了在静水压力作用以及在不同应力状态和应力水平下粉煤灰湿陷变形的规律,得出了粉煤灰湿陷变形的经验计算公式.提出了计算粉煤灰地基湿陷变形的"全应变曲线"增量有限元法.基于本文的试验结果,对一个粉煤灰地基的湿陷变形进行了有限元计算. 相似文献
120.