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1.
目前在河道汇流计算中广泛应用的是马斯京根模型,该模型参数的优化求解是影响能否精确模拟实测水文过程的关键问题.以往的模型参数求解大多采用试错法、矩法等方法,计算过程繁琐,计算精度不高,影响到模型的模拟精度.针对此类问题,笔者将免疫原理与粒子群优化算法有机结合.提出了免疫粒子群优化新方法,有效解决了传统方法的计算结果精度不高的问题,并在马斯京根模型参数优化求解中得以应用,结果表明免疫粒子群算法的计算结果精度令人满意,为河道洪水演算方面研究提供了一种新的研究方法和研究模式.  相似文献   

2.
为了提高MODFLOW中模型计算的精确度,减少不收敛情况的发生,通过建立数值模型算例,分析了不同解算器对计算精度的影响差异、主要参数值的设定对计算精度产生的影响以及收敛指标与迭代次数的定量关系。结果表明,PCG、SAMG和GMG计算精度较高,WHS和SOR计算精度较低。PCG算法中,低收敛指标使得计算精度有所提高,但稳定性却明显降低;计算精度对PCG算法中的阻尼因子的敏感性比对SIP算法中的加速因子敏感性低,二者的减小均导致计算精度降低;SIP算法中,计算过程中的迭代次数、运行时间与水头变化的收敛指标值呈明显的反比关系。当收敛指标设定小于一定值时,迭代次数和收敛指标的对数值呈现明显的线性关系。  相似文献   

3.
主动加热光纤法(AHFO)可实现土体原位含水率的分布式测量,但受场地复杂环境的影响,现有含水率计算模型解译获得的测试结果容易发生较大误差。本文在试验研究的基础上,探究了土体干密度对AHFO法含水率计算的影响,并将支持向量回归(SVR)算法引入含水率的计算模型中,与传统计算模型进行了对比。研究结果表明:土体干密度是影响含水率计算模型精度的重要因素,干密度波动越大则传统计算模型的计算误差也越大,土体较高含水率下会降低计算模型的敏感性;与传统的含水率计算模型相比,考虑干密度影响的径向基核支持向量回归方法具有更高的计算精度,建议在含水率AHFO法的测试中推广应用。  相似文献   

4.
地下水中络合物的计算机模拟   总被引:1,自引:0,他引:1  
张文兵 《世界地质》1998,17(3):79-82
络合物广泛存在地下水中,研究地下水化学成分形成特征,水岩相互作用以及水中各组分浓度变化迁移规律时,必须考虑水中络合物影响,依据化学平衡原理和化学热力学,建立起一般地下水中络合物的化学模型,利用计算机模拟求各个组分和络合物的浓度,使用本方法对大同麻峪口地区水样进行了计算,取得了满意结果。  相似文献   

5.
针对遗传算法存在的缺陷,提出了用小生境方法改进遗传算法。为了提高采空沉陷预测精度,借助Holt-Winters模型的预测功能,应用改进遗传算法求解和优化Holt-Winters模型组合参数,形成了改进遗传算法-Holt-Winters模型组合算法。将组合算法应用于长平高速公路采空区路段沉陷预测,计算表明:改进遗传算法弥补了传统遗传算法易早熟、局部寻优能力弱的缺陷;改进遗传算法-Holt-Winters模型组合算法克服了按梯度试算法搜索质量差和精度不高的缺点,输出稳定性好,预测结果相对误差在2%以内,预测精度显著提高;在采空沉陷中长期预测的相对误差小于0.79%,该算法可用于中长期采空沉陷预测。  相似文献   

6.
在高精度正演计算中,应用有限差分法进行计算时,受傅里叶系数和边界条件的影响较大,导致计算精度不够高,所以对其进行两点改进,以提高其计算精度。在采用有限差分的基础上对傅里叶变换进一步优化,并对边界条件进行改进和校正使其正演结果更加准确。通过对地表电压进行算法验证,认为改进后的结果更接近理论值。并以温纳装置为模型基础,分别建立高低阻模型进行正演对比,通过结果对比可以看出,改进后的计算值精度更好,正演结果受边界影响更小,异常区域更加突出。  相似文献   

7.
铜的氯络合物和硫氢络合物是铜在成矿流体中稳定存在并参与地球化学迁移的重要形式;文中利用量子化学方法B3LYP/LanL2DZ和B3LYP/aug-cc-pVTZ研究计算了Cu+络合物(CuCl、[CuCl2]-、[CuCl3]2-、CuCl(H2O)(真空)、CuHS,0~600℃)和Cu2+络合物(CuCl+、CuCl2(真空)、CuOH+、CuHS+、Cu(HS)2,0~300℃)的简约配分函数比。然后对比前人的理论与计算成果,讨论了不同基组方法计算铜络合物的铜同位素分馏的适应性。计算结果表明:利用LanL2DZ得到的Cu+氯络合物的分馏结果103lnβ65-63比应用其他方法计算的结果偏大;而基于LanL2DZ基组计算Cu2+络合物的结果比aug-cc-pVTZ基组偏小。利用赝势基组LanL2DZ计算铜同位素分馏和实验结果偏差比较大,可能的原因是基于赝势基组LanL2DZ对上述络合物开展结构优化时,键长值比实验值偏大所致。因此,从理论计算上看,利用6-311+G(d,p)基组可能更适合铜络合物的铜同位素分馏计算。虽然这些不同基组计算的结果存在差异,但与前人的实验结果相比,各种理论计算结果都在误差允许范围之内。鉴于此,在利用第一性原理计算同位素分馏系数时,如果计算条件允许,最好利用多种基组计算并作对比分析。  相似文献   

8.
地震波旅行时计算是射线追踪方法的核心问题,其精度直接影响着路径的精度和正演模拟的准确程度。在简要分析目前最典型的几种地震波旅行时计算方法(如有限差分法、线性插值法等)局限性的基础上,提出了一种基于非线性插值的地震波旅行时计算方法,并推导了其计算公式。通过模型的对比试算,不仅验证了所提出的旅行时非线性插值算法的正确性,而且还表明本算法计算旅行时的精度,比Asakawa[5]提出的线性插值算法的精度更高。  相似文献   

9.
狄磊 《地下水》2020,(1):187-189,252
通过引入BA蝙蝠算法解决了传统的PP模型最佳投影方向a变化范围较大的问题,然后选择经济作物损失、粮食损失、成灾面积以及农作物受灾面积4个基本参数评估了庄河市1995~2017年的旱灾状态,其中旱灾评估分级标准利用旱灾投影系列标准差与均值构造,通过对比分析PSO-PP模型评估结果验证了该方法的可行性与准确性。研究表明:BA算法具有更高的计算精度与寻优能力,对最佳投影方向a利用BA算法选取可避免出现寻优结果变化区间过大的问题,且能够显著提升PP模型的精度;研究期间庄河市平均每5年发生一次重大旱灾,随着时间的推移该区域旱灾程度呈不断增大趋势,且变化幅度较为明显。  相似文献   

10.
研究发现,两种目前比较常用的可控源音频磁大地电流法(CSAMT)的正演计算方法,即简化积分法和二次插值法之间计算结果差异较大。为了正确地评价这两种方法的计算精度,本文提出了利用直接积分进行,CSAMT一维正演的算法,即通过将任意角度频率测深 ̄[1]正演结果沿发射源方向直接进行数值积分,得到有限长度发射源的CSAMT正演结果。大量计算和精度评价发现,在这些算法中,简化积分法和本文提出的直接积分法计算结果吻合很好,是精度较高的算法,而二次插值法与前两种算法结果差别较大,是精度较低的算法。  相似文献   

11.
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.  相似文献   

12.
The Global Stratotype Section and Point (GSSP) for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy (SSS) proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy (ICS). The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob's Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.  相似文献   

13.
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.  相似文献   

14.
Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base.  相似文献   

15.
Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators.  相似文献   

16.
东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。  相似文献   

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19.
郯庐断裂南段研究进展与断裂性质讨论   总被引:13,自引:3,他引:13  
据1:5万区域地质调查和专题研究资料,就郯庐断裂带是否南延与消失的原因,其与大别—苏鲁造山带交截形成的假位错效应,以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上,讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。  相似文献   

20.
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.  相似文献   

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