水准测量资料中的地形效应     

王家富  张希 《大地测量与地球动力学》1992,(1)

本文首先用有限元方法对几种不同的地形模型进行了分析。所得的结论是:由于实际地球表面地形的起伏不平,水准测量资料与地形之间具有相关性,即水准点高程变化与该点高程之间呈相关性。最后,本文对今后水准测量资料的分析处理提出了建议。  相似文献   

Opposition polarimetry and photometry of S- and E-type asteroids     

Irina N Belskaya  Vasilij G Shevchenko  Yurij N Krugly  Yurij S Efimov  Alberto Cellino 《Icarus》2003,166(2):276-284

The first results of the observational program devoted to simultaneous investigation of asteroid polarimetric and photometric opposition phenomena are presented. UBVRI polarimetric and V-band photometric observations of the S-type Asteroid 20 Massalia and the E-type Asteroids 214 Aschera and 620 Drakonia were carried out in 1996-1999 down to phase angles of 0.08°, 0.7°, and 1.2°, correspondingly. The S-type Asteroid 20 Massalia is characterized by the pronounced brightness opposition surge with an amplitude larger than that observed for the E-type asteroids. A sharp peak of negative polarization at small phase angles was not observed for this asteroid. The value of polarization degree at phase angle α<1° is less than 0.5% for both S and E types. The negative polarization branches of S and especially E-asteroids have an asymmetrical shape. The phase angle at which the polarization minimum occurs is close to the angle at which non-linear increase begins in the asteroid magnitude phase curves. A relation of the observed effects to the mechanism of coherent backscattering is discussed.  相似文献   

THERMAL EFFECTS OF BUILDING′S EXTERNAL SURFACES IN CITY——Characteristics of Heat Flux into and out of External Wall Surfaces     

ZHANG Yi-ping  HE Yun-ling    LIU Yu-hong  MA You-xin  LI You-rong  DOU Jun-xia     《中国地理科学(英文版)》2004,(4)

1INTRODUCTIONWiththerecentmodernizationandurbanizationofChi-na,urbanareashavegreatlyincreased, andgiantbuild-ings,especiallythosetallerthan100m,havebeendomi-nantincities,whichhave resultedinthegreatincreaseintheproportionofbuilding'sexternalsurfacetototalurbanarea.Thedifferencesofthermalpropertiesmain-lyinducedbysolarradiationbetweenbuilding'sexter-nalsurfacesareobviousfordifferentexposures,whichcaninevitablyinfluencethedistributionsofairtempera-turenearby,eventheverticaldistributionsofurb…  相似文献   

Compaction-induced inclination shallowing of the post-depositional remanent magnetization in a synthetic sediment     

G. L. Anson  K. P. Kodama 《Geophysical Journal International》1987,88(3):673-692

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三峡库首区重点断裂围限区蓄水的加卸载效应     

陈蜀俊  姚运生  蔡永建 《大地测量与地球动力学》2006,26(4):97-101

通过对蓄水前后三峡库首区构造应力场进行三维数值模拟发现,相对于蓄水前,蓄水至135 m水位时,官渡口断裂-马鹿池断裂-牛口断裂围限区、秭归地理中心和九湾溪断裂带,出现了4个主应力下降区和共轭的主应力增长区,形成了差应力场;175 m水位与135 m水位相比,局部差应力场呈现逆向变化,即形成了加载效应与卸载效应的交替过程。这一过程,可能是水库诱发地震的诱震(或触震)因素。  相似文献   

运输系统的区域效应研究   总被引：1，自引：0，他引：1  

高小真 《地理学报》1991,46(1):93-102

运输系统改进—运距缩短—产业布局调整这一空间过程对不同的区域可能具有完全不同的意义。本文通过对一个两区域—两部门经济模型的研究得出结论:当较落后的资源产区与经济中心之间的距离由于运输系统的改进而缩短时,资源产区的经济结构向单一化转变,初级产品的生产和输出在经济建设中逐渐占主导地位,加工工业逐渐萎缩,地方经济发展受到阻碍,而且这种变化是在距离的某一特定值处突然出现的,带有跃变的性质。这一研究结果表明,对区域运输系统的任何改进措施都应该慎而行之,以免造成与本来目标相悖的区域效应。  相似文献   

维生素C对胡子鲶生长、免疫与抗病作用的影响   总被引：2，自引：0，他引：2  

李桂峰  钱沛锋 《广东海洋大学学报》2004,24(4):17-22

在胡子鲶基础料中分别添加 0、5 0 0、10 0 0、15 0 0、2 0 0 0mg/kg的维生素C(VC) ,分别在饲喂不同实验料后的第 12、2 4、36和 5 2天 ,测定各组的生长指标、血清的溶血活力和杀菌活力 ;并在饲喂后的第 4 0天 ,用鲁氏不动杆菌进行攻毒实验 ,观察胡子鲶死亡情况。结果表明 ,添加VC对胡子鲶体重、特定生长率和体长增长率有提高作用 ,但无规律性 ;在添加后的第 12、2 4、36天对血清溶血活力有明显的提高作用 ;对血清杀菌活力没有增强作用。攻毒结果表明 ,VC能明显提高胡子鲶对鲁氏不动杆菌的抵抗力  相似文献   

Short-lived asteroids in the 7/3 Kirkwood gap and their relationship to the Koronis and Eos families     

K. Tsiganis  H. Varvoglis 《Icarus》2003,166(1):131-140

A population of 23 asteroids is currently observed in a very unstable region of the main belt, the 7/3 Kirkwood gap. The small size of these bodies—with the notable exception of (677) Aaltje (∼30 km)—as well as the computation of their dynamical lifetimes (3<T_D<172 Myr) shows that they cannot be on their primordial orbits, but were recently injected in the resonance. The distribution of inclinations appears to be bimodal, the two peaks being close to 2° and 10°. We argue that the resonant population is constantly being replenished by the slow leakage of asteroids from both the Koronis (I∼2°) and Eos (I∼10°) families, due to the drift of their semi-major axes, caused by the Yarkovsky effect. Assuming previously reported values for the Yarkovsky mean drift rate, we calculate the flux of family members needed to sustain the currently observed population in steady state. The number densities with respect to semi-major axis of the observed members of both families are in very good agreement with our calculations. The fact that (677) Aaltje is currently observed in the resonance is most likely an exceptional event. This asteroid should not be genetically related to any of the above families. Its size and the eccentricity of its orbit suggest that the Yarkovsky effect should have been less efficient in transporting this body to the resonance than close encounters with Ceres.  相似文献   

电测深ρ＿s差值法的应用效果     

杨昌桂 《湖南地质》1994,(1)

用电测深研究地电断面、寻找隐伏多金属矿体时，以往采用ρ＿ｓ（或η＿ｓ）等值线断面图进行地质推断解释，因受浅源信号的干扰，效果差。本文提出了采用ρ＿ｓ（或η＿ｓ）差值法，能排除浅源干扰信号，反映出地电断面的相对变化，突出了深部微弱信息，取得了较好的地质解释效果。  相似文献   

RETRACTION: Numerical simulation of a wind-sand flow under different conditions of atmospheric stability     

LÜ PING  ZHIBAO DONG 《Sedimentology》2008,55(3):721-721

A theoretical model for wind‐sand flow is developed by considering the coupling between wind flow and sand particle motion, the latter subject to the Magnus effect, under different atmospheric stability conditions. Using this model, the characteristics of the wind‐sand flow are discussed in detail. The results show that the atmospheric stability and the Magnus effect both have a strong influence on wind profiles and on the trajectories of sand particles. This approach produces results with characteristics that differ from those previously reported; the latter only applying to atmospheric conditions of neutral stability. The saltating sand reaches a greater height under non‐neutral stability than under neutral stability, while the maximum horizontal distance is greater under unstable conditions and is smaller under stable conditions than under conditions of neutral stability.  相似文献