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91.
矿物中U、Th及其子核进行α衰变释放出α粒子时,剩余重核受到反冲而产生辐射损伤。在适当的条件下经化学蚀刻,这些辐射损伤成为在相干涉反差显微镜下可观测的核径迹。实验证明,蚀刻过程中,Alpha反冲径迹(ARTs)增长数和蚀刻时间成线性关系,随蚀刻时间增加,线性被破坏,最终达到一个“坪”。退火过程表明,Alpha反冲径迹的退火要比裂变径迹的退火容易,其退火率随退火时间的增长和温度的升高而增加,且温度对其影响显著,在350℃下加热样品20h,退火率达到90%左右,在400℃下加热4h,完成全退火。 相似文献
92.
The study zone is located in the city of Padova (the Veneto region, NE Italy). The industrial activities present in this area
since 1950 have produced very high concentrations of Pb, Zn, Cu, Pcb and oils until a depth of 7 m. The unsaturated and the
saturated zones are both polluted. Because of the abundance of Pb values it was decided to analyze the lead distribution in
the studied zone. In many studies of the polluted sites, the geometry of the investigated volume is highly anisotropic. Generally
we have an extension of some hectares in the horizontal plane and of a few meters in depth. It is likely that different horizontal
spatial continuity structures in pollution distribution are found at different depths both for the layered nature of the medium
and for the transition between unsaturated and saturated conditions. In such conditions the decision to divide a 3D problem
into 1D and 2D problems can be useful. Initially the studied volume was divided into seven layers up to 5 m in depth; the
study was then approached in two phases. First, the Pb values in the vertical direction were analyzed, considering a derive
along z, and estimating the values using the Kriging with Trend (KT) method. Thus it was possible to increase the data in the z direction, especially in the deeper layers. Second, 500 realizations of the Pb distribution for each of the seven layers
were simulated using the simulated annealing procedure. Finally, results were presented and discussed for each layer in terms
of median and probability maps. 相似文献
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96.
Modeling of Fluvial Reservoirs with Object Models 总被引:16,自引:0,他引:16
An object model for fluvial reservoirs that has been developed from 1985 to present is described. It uses a formal mathematical object model (marked point process) describing the distributions of four facies: channel, crevasse, barrier, and background. Realisations from the model are generated using the Metropolis-Hastings simulation algorithm with simulated annealing conditioning on the volume ratios and well observations. The main challenge has been to find a suitable parameterization of the geology of fluvial reservoirs, and to find and implement the generating function of the channels in the simulation algorithm. The model and simulation algorithm can be conditioned on arbitrary well paths including horizontal wells and paths with partly missing observations, well test data, well contacts, seismic data, and general geological knowledge. 相似文献
97.
新月形沙丘形态的模拟实验研究 总被引:10,自引:1,他引:9
新月形沙丘是风沙地貌基本形态之一,一般为高浓度非饱和风沙流所塑造。其形成过程始于风沙运动的“波粒二重性”,并经历沙物质积累(高浓度饱和风沙流)和形体塑造(高浓度不饱和风沙流)两个发育阶段,即耗散性增大和色散性减小过程;非沙质床面零星分布的单个新月形沙丘具有明显的移动性和形态的不稳定性(高大新月形沙山除外)。风洞实验条件下形成的新月形沙丘形态(其尺度比床面沙纹大一个数量级),有助于新月形沙丘形成机制的了解。 相似文献
98.
The VLF-R (very low frequency-resistivity) data, i.e. the apparent resistivity ( ρ a ) and phase ( φ ) data, were inverted individually and jointly using the VFSA (very fast simulated annealing) global inversion approach. Global inversion results for synthetic data without and with various amounts of random and normally distributed Gaussian noise reveal that the inversion of neither the ρ a nor φ data alone yields the true parameters of the structures. However, the joint inversion of the ρ a and φ data yields very good estimates of the model parameters. Five models, representing typical subsurface structures in the shield areas, are studied here. Various models achieved after 10 VFSA runs were used to compute the mean model and the corresponding covariance and correlation matrices, which were used to estimate the uncertainties in the mean model parameters and correlations between the model parameters. We observe that these correlations follow the physics associated with the problem. VLF-R field data due to a nearly vertical contact structure and a very thick dyke-like structure were also inverted to demonstrate the efficacy of the approach in the delineation of the parameters of 2-D structures. 相似文献
99.
挪威某些铜镍矿石中单斜磁黄铁矿出溶体的退火和粗化 总被引:4,自引:0,他引:4
在挪威某些正岩浆铜镍矿床的矿石中,六万磁黄铁矿基质内的单斜磁黄铁矿叶片是高温时形成的磁黄铁矿固溶体在降温过程中出溶的产物。出溶叶片宽度和间距的加大、叶片的带状分布、楔形尖端、箱状扭曲和复杂叶片等结构,表明出溶产物在不高于单斜-六方转变温度(254℃)的条件下发生过显著的退火和粗化。重结晶的六方磁黄铁矿基质中所保存的单斜变种甚少,表明变质作用所引起的矿石重结晶,可使磁黄铁矿吸收其中的单斜出溶体而发生均匀化。 相似文献
100.
磷灰石裂变径迹分析(AFTA)——一种研究含油气盆地古热构造史的新方法 总被引:2,自引:0,他引:2
磷灰石裂变径迹分析近年来广泛地被用来研究含油气盆地古热定史与古构造史及指导油气勘探,这主要是根据磷灰石裂变径迹退火是时间和温度的函数,而烃的生成与热成熟同是也是和温度的函数,而且磷灰石裂变径迹退火温度范围与石油的生成门限相吻合,退火除受温度、时间影响外、还受化学成分,取向因素控制。AFTA包括裂变径迹年龄分析和裂变径迹长度分析,通过前者可获得退火方面信息,通过后者可获得最大古地温及其随时间的变化及 相似文献