首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 218 毫秒
1.
本文就GM(1,1)传统模型及其辨识值求解模型做了一定探讨。GM(1,1)传统模型的本质是曲线拟合,然而此曲线对于各历史点的拟合是最优的,但对于预测未来值不一定最优;传统灰色预测辨识值求解模型采用等权最小二乘法,认为各已知历史点的一次累加值与实测值累加值的误差对辨识值模型的权值均为1,未考虑时间因素,在理论上存在一定缺陷。本文提出一种时间加权辨识值求解模型,用加权最小二乘求解辨识值,进而求出系统预测方程,并用MATLAB语言编写了改进的灰色预测模型程序。将本文提出的模型应用到超高层建筑物的变形预测中,将改进预测模型预测结果与传统方法得到的预测结果进行比较,证明本文提出的改进模型具有较好的实用性和参考价值。  相似文献   

2.
关于几种经济预测模型的应用研究   总被引:7,自引:3,他引:4  
在社会经济的各个领域,大量的决策问题离不开对变量未来值的预测或对不易观测变量的预测。而在进行预测的过程中,最重要的是预测模型的选择。本文着重研究了经济预测中常用的线性回归模型、灰色预测模型和RBF神经网络模型,并且引入组合预测模型对这三种单项预测模型进行优化。通过对天津港货物吞吐量预测的实例分析,检验了这些方模型的可行性和可靠性,为决策者制定相应的战略规划提供了科学的参考依据。  相似文献   

3.
根据武汉市2001—2010年固定资产投资数据,利用灰色预测理论对未来几年的投资进行预测。文章在分析灰色理论的基础上,结合实际情况构建GM(1,1)预测模型,并用于对武汉市2001—2010年全社会固定资产投资进行拟合,同时为保证模型预测的高精度,引入了新陈代谢思想,即加入新数据的同时丢弃较"老"的数据,使拟合精度进一步提高。通过对模拟投资值与实际投资值进行比较,并且对模型精度进行检验,证实该预测模型具有较高的预测精度,其精度等级为"好",可用于对武汉市未来几年全社会固定资产投资进行预测,预测结果具有一定的参考价值。  相似文献   

4.
研究由低维非线性动力系统所产生的混沌时序的预测方法及其应用。通过改进的最小二乘方法来估计模型的参数,并在其相空间中对时序的未来值进行预测。给出了有代表性的实例对本文的模型和算法进行验证。结果发现选取最佳的模型阶数能增加预测的准确程度,且混沌时序不可能进行长期的预测。算例表明本文建议的方法是有效的。  相似文献   

5.
利用时间序列在t时刻的有效观测值去预测在某个未来时刻t+l的值,并建立自回归移动平均(ARMA)模型,以MATLAB为工具,亚泰集团360个交易日的数据作为样本,预测10天股市的收盘价;并与含有一个隐含层的BP网络模型进行对比,结果表明自回归移动平均(ARMA)模型算法对短期股价预测的精度较高.  相似文献   

6.
基于信息融合的网络安全态势感知模型   总被引:2,自引:0,他引:2  
在分析已有的安全态势评估和预测方法的基础上,提出了基于信息融合的网络安全态势感知模型.该模型采用D-S证据理论对多源网络安全数据进行融合,计算漏洞、服务、主机、网络的安全态势值.同时根据历史安全态势评估结果,利用支持向量回归理论对未来态势进行预测.相比已有的安全态势评估和预测方法,该模型的结构更加完整,结果更为准确有效.  相似文献   

7.
以支持向量机(SVM)为基础提出一种网络安全态势预测方法.SVM可以借助于已有的网络安全态势值对未来安全进行预测,并引入了遗传算法对SVM进行参数优化,进而提升其预测效率.仿真结果表明,此模型在预测网络安全态势变化趋势方面有着很好的前景,能够显著提升预测精度,相较于传统预测技术优势显著,更契合当前的互联网环境.  相似文献   

8.
为检验灰色模型及径向神经网络模型用于短时交通流预测的可行性及适用性,本文分析和比较了灰色模型GM(1,1)和RBF径向神经网络模型对短时交通流的预测效果。仿真实例表明,灰色模型不适合用于短时交通流预测,而径向神经网络能够准确预测短期交通流的未来变化趋势,当径向基函数的分布密度值在0.8~1.0之间时能够取得较高的预测精度。  相似文献   

9.
柳茂盛 《广东科技》2012,21(9):196-197
根据改进马尔可夫链预测方法,汇总分析了陕西省榆林市韩家峁水文站15年的年降雨量,采用均值一标准差分级法。结果表明:应用马尔可夫链模型预测未来年降雨量,显示了较高的可信度和可行性,并对2004年降雨量进行分析预测,根据模糊集理论中的特征值预测降雨量。结果显示预测值与实际值情况吻合。  相似文献   

10.
ARIMA模型静态预测精确度较高,但是只能预测下一期的值,动态预测可以预测多期的值,但是不能很好的给出股价走势.现以股票价格走势为例,首先利用ARIMA模型动态的预测序列未来多期的值,再结合傅里叶级数预测法建立修正的预测模型,以得到较为准确的股价走势.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

18.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

19.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

20.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号