遗传算法用于多组分同时测定     

杨兵  王洪艳  陈淑桂  沙志芳 《吉林大学学报(地球科学版)》1999,29(2):193-196

采用遗传算法（ＧＡ）进行了地质样品中的贵金属Ｐｄ、Ｒｕ、Ａｕ三组分的同时测定,并讨论了遗传算法的基本原理、数学模型的建立、目标检验函数、初始值范围、搜索范围、交配、变异概率等对计算结果的影响,证明了遗传算法用于多组分测定的可行性。  相似文献   

太阳的空间观测与研究Ι—太阳电磁波 辐射的观测与研究概况     

纪树臣 《天文研究与技术》1999,(2):25

太阳空间观测为揭示太阳新的观测现象与研究开拓了新的途径。空间观测具有全波段、全时段、全方位以及无大气抖动和大气散射光等观测优点。本文着重探讨了太阳空间长波射电观测、Ｘ射线观测、紫外线观测的成就与研究结果。这些波段（包括光学）的爆发均起因于太阳大气中被加速的荷能电子与太阳等离子体、磁场相互作用而产生的电磁辐射,其能量约占太阳耀斑总量的１／４,即１０２５Ｊ。  相似文献   

基于AHP-熵-TOPSIS对极轨气象卫星应用系统健康程度评价指标体系     

邢开云  贾树泽  赵现纲  冯小虎 《气象科技》2020,48(4):482-489

以实现对极轨气象卫星应用系统健康程度进行综合评价为目的,提出结合主观分析的层次分析法(Analytic Hierarchy Process,AHP)和客观分析的熵权法(Entropy Weight,EW)确定待评价系统指标值的综合权重,再采用逼近理想解排序法(Technique for Order Preference by Similarity to an Ideal Solution,TOPSIS)对系统的指标进行多角度评价排序来作为最终评价结果。本文根据连续5个月3颗极轨气象卫星在实际业务系统运行中异常指标样本进行实证分析。结果表明该方法较为全面考虑了影响应用系统的多种因素,避免了单一判据的局限性,并对各指标的重要性进行综合对比分析,使得评价结果更科学准确,可以作为构建极轨气象卫星应用系统健康程度评价指标体系的一种方法。  相似文献   

多组份电解质溶液热力学——活度系数和渗透系数与高次极限定律的关联   总被引：1，自引：0，他引：1  

杨家振  宋彭生 《盐湖研究》1993,(1)

自1973年Pitzer电解质溶液理论问世以来,它在海洋学、地球科学、生物学乃至化工中获得了广泛的应用。本文介绍在实际应用中有重要意义的高次极限定律及与活度系数、渗透系数间的关联,它们是Pitzer理论发展的重要组成部份。  相似文献   

上海城市游憩者流动行为研究   总被引：165，自引：9，他引：165  

吴必虎 《地理学报》1994,49(2):117-127

由参与游憩活动的本地居民和外来游客共同构成城市游憩者。城市游憩者在空间上的流动规律将影响城市游憩设施和旅游资源的开发管理。通过旅行测定手段获得基本数据，运用游憩活动空间和使用曲线分析技术，研究上海城市游憩者的流动规律。  相似文献   

Limestone solution rates and processes in the Waitomo District,New Zealand     

John Gunn 《地球表面变化过程与地形》1981,6(5):427-445

Karst solution processes are investigated on Oligocene limestones in the Waitomo district, west central North Island, New Zealand. Estimates of the inputs, throughputs and outputs of water and dissolved calcium and magnesium in two drainage basins were used to establish the rate of limestone solution by autogenic waters. The best estimate for solution loss from the basins during the study year is 69 m³/km². The potential measurement errors inherent in each parameter used in the erosion rate computations were assessed and the probable maximum and minimum erosion rates were estimated to be 88 and 61 m³/km². In both basins approximately 67 per cent of the annual solute load is transported by flows greater than the mean annual discharge, over 15 per cent being transported by flood flows that are exceeded only 5 per cent of the time. Almost half of the annual load is transported during the three winter months (June-August), but no one month accounts for more than 18 per cent or less than 2.7 per cent of the annual total. Approximately 37 per cent of solution takes place within the soil profile, and most of the remainder is concentrated in 5–10 m of weathered bedrock (the subcutaneous zone) beneath this. Thus, it is likely that at least 85 per cent of the total solutional erosion contributes to the surface lowering of soil and bedrock.  相似文献   

NARX neural network approach for the monthly prediction of groundwater levels in Sylhet Sadar,Bangladesh          下载免费PDF全文

Abdullah Al Jami  Meher Uddin Himel  Khairul Hasan  Shilpy Rani Basak  Ayesha Ferdous Mita 《地下水科学与工程》2020,8(2):118-126

Groundwater is important for managing the water supply in agricultural countries like Bangladesh. Therefore, the ability to predict the changes of groundwater level is necessary for jointly planning the uses of groundwater resources. In this study, a new nonlinear autoregressive with exogenous inputs(NARX) network has been applied to simulate monthly groundwater levels in a well of Sylhet Sadar at a local scale. The Levenberg-Marquardt(LM) and Bayesian Regularization(BR) algorithms were used to train the NARX network, and the results were compared to determine the best architecture for predicting monthly groundwater levels over time. The comparison between LM and BR showed that NARX-BR has advantages over predicting monthly levels based on the Mean Squared Error(MSE), coefficient of determination(R~2), and Nash-Sutcliffe coefficient of efficiency(NSE). The results show that BR is the most accurate method for predicting groundwater levels with an error of ± 0.35 m. This method is applied to the management of irrigation water source, which provides important information for the prediction of local groundwater fluctuation at local level during a short period.  相似文献   

Space group and hydrogen sites of δ-AlOOH and implications for a hypothetical high-pressure form of Mg(OH)<Subscript>2</Subscript>     

Y. ?KudohEmail author  T. ?Kuribayashi  A. ?Suzuki  E. ?Ohtani  T. ?Kamada 《Physics and Chemistry of Minerals》2004,31(6):360-364

The space group and hydrogen positions of -(Al_0.84Mg_0.07Si_0.09)OOH are investigated using a single crystal synthesized using a multi-anvil apparatus under conditions of 1000 °C and 21 GPa. The space group determined by single-crystal X-ray diffraction is to Pnn2, with unit-cell parameters of a=4.6975(8) Å, b= 4.2060(6) Å, c=2.8327(4) Å, and V=55.97(1) ų. Partial occupancy of the Al site by Mg and Si suggests the possibility of a limited solid solution between -AlOOH, stishovite, and a hypothetical CaCl₂-type Mg(OH)₂ that is 16% denser than brucite. Difference-Fourier maps reveal two small but significant Fourier peaks attributable to hydrogen atoms. Atomic distances and angles around the first peak indicate a hydrogen bond with O···O distances of 2.511 Å, while those around the second peak are suggestive of a bifurcated hydrogen bond with O···O distances of 2.743 and 2.743 Å.  相似文献   

嵌入式数字城市空间管治地理信息系统     

周立 《现代测绘》2004,27(5):21-23

探讨了数字城市空间管治Mobile GIS的技术路线。通过城市空间管治动态信息采集、空间决策支持需求分析，设计实现了基于MapX Mobile的数字城市空间管治移动GIS系统。  相似文献   

对流天气临近预报技术的发展与研究进展   总被引：34，自引：11，他引：34       下载免费PDF全文

陈明轩俞小鼎  谭晓光王迎春 《应用气象学报》2004,15(6):754-766

目前，临近预报技术主要包括雷暴识别追踪和外推预报技术、数值预报技术以及以分析观测资料为主的概念模型预报技术等。其中，识别追踪和外推预报技术主要以雷达资料为基础，在这方面，交叉相关外推和回波特征追踪识别外推是比较成熟的技术，已经用于许多的临近预报业务系统中，其缺陷是预报时效较短，准确率也不是很高。随着精细数值天气预报技术和计算机技术的发展，利用多普勒天气雷达资料和其它中小尺度观测资料进行数值模式初始化，来预报雷暴的发生、发展和消亡已经成为一个研究的热点，该技术发展很快但还不成熟。概念模型预报技术主要是通过综合分析多种中小尺度观测资料，包括雷达和气象卫星资料等，在此基础上建立雷暴发生、发展和消亡的概念模型，特别是边界层辐合线和强对流的密切关系等，再结合数值模式分析预报和其它外推技术的结果，然后建立雷暴临近预报的专家系统，其不但可以获取雷暴和对流降水移动、发展的信息，还可以预报它们的生成和消亡。检验和定性评估也表明，将多种资料和技术集于一体的概念模型专家系统，其临近预报的准确率最高，时效也最长，是临近预报技术未来发展的主要趋势之一。NCAR的Auto Nowcaster系统是雷暴临近预报概念模型专家系统的一个典型代表。  相似文献