相律的应用:蒸发结晶过程自由度          下载免费PDF全文

房春晖  宋彭生 《盐湖研究》1993,(1)

在连续原理和浓度限制条件的基础上,分析了卤水蒸发过程的自由度,提出了“蒸发结晶过程自由度”这一概念。发现蒸发结晶过程自由度在整个过程中不是1便是0,在1和0之间交替变化,与选择的组分数和析出固相数目无关。蒸发结晶过程自由度为1,物理意义是在不引起新相产生旧相不消失的前提下过程连续地变化(水分的连续蒸失),几何意义是指在适当的坐标系中的一条线,一条直线或曲线;0的物理意义是指新相的产生和旧相的即将消失或者前一段的连续变化过渡到后一段的连续变化,几何意义是指一点,两蒸发阶段的交点或者过程的终点。简单地讨论了过程的单向性和连续件。  相似文献   

可可西里——东昆仑活动构造带强震活动研究   总被引：13，自引：0，他引：13  

张国民  田勤俭  王辉 《地学前缘》2003,10(1):39-46

青海昆仑山口西 8.1级地震发生在具有新生性特征的可可西里—东昆仑活动断裂带上。该断裂带在 190 0年以来的 10 0多年中经历了一个强震活动过程。在该强震活动过程中 ,地震沿整个可可西里—东昆仑活动构造带分段破裂 ,强震的破裂长度和震级之间大致满足对数线性的统计关系 ,强震活动呈现指数型时间分布的加速特征。这种强震加速活动特征可以用含多个震源体的孕震系统的强震成组活动模型给予解释。  相似文献   

辽宁义县—北票地区义县组地层层序——义县阶标准地层剖面建立和研究之一   总被引：30，自引：1，他引：30  

王五力  张宏  张立君  郑少林  杨芳林  李之彤  郑月娟 《地层学杂志》2003,27(3):227-232

义县地区广义的义县组可解体为王家屯组 (暂命名 )和义县组 ;分属王家屯和义县火山旋回 ,前者为偏酸、偏碱性 ,后者主体为中基性、末期为中酸性火山岩系 ,并广泛发育潜火山岩相的玄武玢岩、安山玢岩和火山集块角砾熔岩筒。该区有七个主要沉积层 ,自下而上分别为王家屯组马神庙层、义县组老公沟层、业南沟层、砖城子层、大康堡层、朱家沟层和金刚山层 ;产有较丰富的无脊椎动物、脊椎动物和植物化石。以砖城子层、大康堡层和金刚山层为界 ,义县火山旋回可划分为 4个亚旋回 ,分别代表火山活动的初始期、主期、晚期和末期。北票四合屯地区的义县组相当义县地区义县组的第一和第二亚旋回 ,含鸟类化石的主沉积层 (尖山沟层和上园层 )可与砖城子层对比  相似文献   

山东昌乐蓝宝石颜色与化学成分的关系     

张培强 《山东国土资源》2000,(2)

产于玄武岩中的蓝宝石颜色通常较深 ,山东昌乐蓝宝石的颜色因其晶体巨大更显得深暗。这类蓝宝石曾多次进行过改色试验 ,但成效都不大。通过对电子探针及紫外—可见光—近红外吸收光谱图测试结果的分析 ,并对山东昌乐蓝宝石的颜色与化学成分之间的关系进行研究 ,结果表明 :昌乐蓝宝石的主要致色元素为Fe,Ti,Cr,Ni等 ,Fe2 O3 FeO含量高及TiO2含量少 ,以及成对Fe3 的大量存在是其颜色偏深的重要原因 ;TiO2 含量对蓝宝石颜色纯度影响很大 ,也是蓝宝石改色能否成功的重要因素之一。  相似文献   

Research on Parallel Algorithms for uv-faceting Imaging     

《Chinese Astronomy and Astrophysics》2019,43(3):424-443

The uv-faceting imaging is one of the widely used large field of view imaging technologies, and will be adopted for the data processing of the low-frequency array in the first stage of the Square Kilometre Array (SKA1). Due to the scale of the raw data of SKA1 is unprecedentedly large, the efficiency of data processing directly using the original uv-faceting imaging will be very low. Therefore, a uv-faceting imaging algorithm based on the MPI (Message Passing Interface)+OpenMP (Open Multi-Processing) and a uv-faceting imaging algorithm based on the MPI+CUDA (Compute Unified Device Architecture) are proposed. The most time-consuming data reading and gridding in the algorithm are optimized in parallel. The verification results show that the results of the proposed two algorithms are basically consistent with that obtained by the current mainstream data processing software CASA (Common Astronomy Software Applications), which indicates that the proposed two algorithms are basically correct. Further analysis of the accuracy and total running time shows that the MPI+CUDA method is better than the MPI+OpenMP method in both the correctness rate and running speed. The performance test results show that the proposed algorithms are effective and have certain extensibility.  相似文献   

Study of Star/Galaxy Classification Based on the XGBoost Algorithm     

《Chinese Astronomy and Astrophysics》2019,43(4):539-548

Machine learning has achieved great success in many areas today. The lifting algorithm has a strong ability to adapt to various scenarios with a high accuracy, and has played a great role in many fields. But in astronomy, the application of lifting algorithms is still rare. In response to the low classification accuracy of the dark star/galaxy source set in the Sloan Digital Sky Survey (SDSS), a new research result of machine learning, eXtreme Gradient Boosting (XGBoost), has been introduced. The complete photometric data set is obtained from the SDSS-DR7, and divided into a bright source set and a dark source set according to the star magnitude. Firstly, the ten-fold cross-validation method is used for the bright source set and the dark source set respectively, and the XGBoost algorithm is used to establish the star/galaxy classification model. Then, the grid search and other methods are used to adjust the XGBoost parameters. Finally, based on the galaxy classification accuracy and other indicators, the classification results are analyzed, by comparing with the models of function tree (FT), Adaptive boosting (Adaboost), Random Forest (RF), Gradient Boosting Decision Tree (GBDT), Stacked Denoising AutoEncoders (SDAE), and Deep Belief Nets (DBN). The experimental results show that, the XGBoost improves the classification accuracy of galaxies in the dark source classification by nearly 10% as compared to the function tree algorithm, and improves the classification accuracy of sources with the darkest magnitudes in the dark source set by nearly 5% as compared to the function tree algorithm. Compared with other traditional machine learning algorithms and deep neural networks, the XGBoost also has different degrees of improvement.  相似文献   

福建长乐西施舌资源现状及保护成效研究          下载免费PDF全文

林建杰 《应用海洋学学报》2020,39(4):551-558

2018年4月在“福建省长乐海蚌资源增殖保护区”及其邻近海域布设31个站位进行底拖网调查取样,共鉴定渔获物45种,其中甲壳类21种、贝类14种、鱼类10种。西施舌（Mactra antiquata）的站位出现率为38.71%。站位的质量密度平均为975.68 kg/km²（0～23 384.53 kg/km²）,个数密度平均为2.983×10⁴个/km²（0～59.607×10⁴个/km²）。西施舌种群在渔获物中的IRI值高达 1 556.5 \[仅次于截形白樱蛤(Psammacoma gubernaculum)],为优势种,表明西施舌在保护区生物资源组成中占有重要的地位;保护区内西施舌的站位出现率及质量密度明显高于区外,表明西施舌资源主要集中分布于保护区范围内;西施舌种群的年龄组分布较广,年龄结构较为合理。大部分西施舌均达到性成熟年龄和大小,表明资源具有可持续发展的潜力。与2006年和2012年的调查结果相比,保护区2018年西施舌资源比2012年有显著提高,分布范围亦有明显扩大,但尚未恢复到2006年的总体水平。综上可以看出,西施舌资源保护区范围总体界定合理,西施舌资源保护显见成效;“福建省长乐海蚌资源增殖保护区”范围内不同区块实行不同程度的禁捕、限捕管控,2011年以来累计放流西施舌种苗253.07万粒,对于西施舌资源恢复和养护管理是有效的举措。  相似文献   

An Automatic Method for Detecting Transients and Variable Sources in AST3 Survey Based on Image Subtraction and Random Forest     

《Chinese Astronomy and Astrophysics》2020,44(1):41-60

AST3-2 (the second Antarctic Survey Telescope) is located in Antarctic Dome A, the loftiest ice dome on the Antarctic Plateau. It produces a huge amount of observational data which require a more efficient data reduction program to be developed. Also the data transmission in Antarctica is much difficult, thus it is necessary to perform data reduction and detect variable and transient sources remotely and automatically in Antarctica, but this attempt is restricted by the unsatisfactory performance of the low power consumption computer in Antarctica. For realizing this purpose, to develop a new method based on the existing image subtraction method and random forest algorithm, taking the AST3-2 2016 dataset as the test sample, becomes an alternative choice. This method performs image subtraction on the dataset, then applies the principle component analysis to extract the features of residual images. Random forest is used as a machine learning classifier, and in the test a recall rate of 97% is resulted for the positive sample. Our work has verified the feasibility and accuracy of this method, and finally found out a batch of candidates for variable stars in the AST3-2 2016 dataset.  相似文献   

Photometric Follow-up Transit (Primary Eclipse) Observations of WASP-43 b and TrES-3b and A Study on Their Transit Timing Variations     

Sun Zhao  Ji Jiang-hui  Dong Yao 《Chinese Astronomy and Astrophysics》2018,42(1):101-128

Two photometric follow-up transit (primary eclipse) observations on WASP-43 b and four observations on TrES-3 b are performed using the Xuyi Near-Earth Object Survey Telescope. After differential photometry and light curve analysis, the physical parameters of the two systems are obtained and are in good match with the literature. Combining with transit data from a lot of literature, the residuals (O ? C) of transit observations of both systems are fitted with the linear and quadratic functions. With the linear fitting, the periods and transit timing variations (TTVs) of the planets are obtained, and no obvious periodic TTV signal is found in both systems after an analysis. The maximum mass of a perturbing planet located at the 1:2 mean motion resonance (MMR) for WASP-43 b and TrES-3 b is estimated to be 1.826 and 1.504 Earth mass, respectively. By quadratic fitting, it is confirmed that WASP-43 b may have a long-term TTV which means an orbital decay. The decay rate is shown to be P? = (?0.005248 ± 0.001714) s·yr^?1, and compared with the previous results. Based on this, the lower limit of the stellar tidal quality parameter of WASP-43 is calculated to be ${Q^{\prime }}_{*}\ge 1.5\times {10}^5$, and the remaining lifetimes of the planets are presented for the different ${Q^{\prime }}_{*}$ values of the two systems, correspondingly.  相似文献   

安徽铜陵地区含金硫化物矿床成矿作用     

戴瑞榕 《大地构造与成矿学》1991,15(1):23-30

铜陵地区位于华中地洼区,苏鄂地洼系。具工业价值的金矿床多赋存于地洼期次一级构造以及它们的交汇处,这是本区构造控矿的特点。近矿围岩以地台型碳酸盐岩为主,矿体明显受地层层位控制。与矿化有关的侵入岩,主要形成于地洼期(燕山早、中期)。岩体形成后叠加了成矿热液的多次活动。金的成矿作用及金矿床的形成,通常与含金丰度相对较高的地台构造层有密切的成因联系,它们提供了重要的物质来源,可认为是矿源层(Source beds)。本区各主要矿床是以地洼型岩浆期后热液作用为主的多因复成层控含金硫化物矿床。  相似文献