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1.
基于经济变量和状态的模糊性,建立计量经济模型,运用模糊聚类(FCM)算法对样本空间进行聚类划分,获取模糊相似矩阵,优化经济变量输入输出关系,对经济变量进行拟合和预测.将模糊聚类方法用于复杂的能源系统,对我国能源生产进行预测,把预测结果与实际值进行了比较,结果表明误差较小,同时还将此预测与多元回归预测进行比较,结果表明用模糊方法对能源生产进行预测效果更好.用同样的方法可以对经济领域中诸如消费、货币需求、产品需求等进行预测,其应用领域是广泛的.  相似文献   

2.
建立一种基于空间的逻辑回归模型用于分析和预测城市扩展,这种模型利用空间滤波对因子进行空间平滑得出"隐含变量",从而把原始变量变换为没有空间相关的新变量.利用该模型对新堡市的土地利用变化进行了分析和预测.实验结果表明,新方法比普通逻辑回归模型的预测精度有较大提高,曲线下面积从0.74提高到0.84.  相似文献   

3.
提出了一种基于多变量相重构的混沌时间序列预测方法.该预测方法从非线性动力学系统中获取与待预测时间序列相关的信息组成多变量时间序列,首先进行多变量相空间重构,然后利用局域多元线性回归模型在相空间中进行预测,最后从预测出的高维相点中分离出时间序列的预测值.由于考虑了动力学系统中多个变量之间相互耦合的关系,从而增加了重构相空间的系统信息量,使得相空间的相点轨迹更加逼近原系统的动力学行为.与采用单变量进行预测的方法相比,基于多变量相重构的预测方法无论是单步预测还是多步预测,都能有效地提高预测精度,且具有嵌入维数的选择对预测精度影响较小的优点.通过对Lorenz混沌信号进行预测,实验结果验证了方法的有效性.  相似文献   

4.
文章对中国民用汽车拥有量及相关经济变量1985—2015年的年度数据进行了多层面分析.建立单变量Logistic时序模型,对未来民用汽车拥有量进行预测;建立双变量弹性分析模型,研究单个经济变量每变动1%对民用汽车拥有量的影响程度;建立多元线性回归模型,发现人口总数、工业增加值、钢材产量和全国居民消费水平与民用汽车拥有量之间的线性关系.  相似文献   

5.
居民消费价格指数是国民经济发展中的重要宏观监控指标之一,由定性分析预测得出可能影响居民消费价格指数的解释变量,选取我国1996年以来的有关数据,通过EVIEWS软件进行对各变量进行计量分析,建立数学模型分析得出货币供应量、国内生产总值和物价水平有较强的正相关关系,并在此基础上提出建议分析.  相似文献   

6.
全林 《上海交通大学学报》2000,34(11):1549-1552
通过分析与我国宏观经济物价变动密切相关的主要经济变量以及变量以及变量与物价之间的关系,建立我国宏观经济物价模型,得出“高增长、低通胀”的结论,并在此基础上对我国未来的物价水平,走势出大胆预测,对指导我国经济稳定、健康、持续的发展具有现实意义。  相似文献   

7.
封之聪  祝云  高枫 《科学技术与工程》2022,22(26):11394-11401
在火力发电过程中,蒸汽量的准确测量,对于汽轮机机组的经济稳定运行具有重要的意义。针对传统蒸汽量测量方法精度低的问题,提出了一种基于宽度学习系统(broad learning system, BLS)和Lasso (least absolute shrinkage and selection operator)回归模型的组合预测模型。首先利用One-class SVM (one-class support vector machines)算法对样本进行异常值检测,将检测得到的异常值剔除。然后,采用最大信息系数(maximal informationcoefficient, MIC)对特征变量和蒸汽量进行非线性关联性分析,确定宽度学习系统和Lasso回归模型的输入变量,通过训练得出各自的预测结果。最后,通过最优加权组合法确定两单一模型的权重系数,将它们所得的预测结果线性组合,得到最终的预测结果。实例表明,所建立的组合模型有效地缓解了单一模型在变化剧烈的峰值和谷值预测偏差大的问题,能够准确地预测蒸汽量。  相似文献   

8.
闫冬梅  蒋蓉 《甘肃科技》2012,28(16):19-20
针对芳烃抽提装置水系统具有多变量、时变、非线性、强耦合、干扰因素多等特点,对水系统控制策略进行了研究,提出了专家控制、多变量预测控制综合使用技术,采用专家控制、多变量预测控制技术建立了水系统生产过程先进控制系统,使水系统先进控制投运取得成功应用.  相似文献   

9.
模型预测控制因其解耦性和强鲁棒性得以在过程控制中广泛使用.在实际生产过程中,因操作需要常常放开控制器对部分操作变量的控制,此部分操作变量则转化为前馈变量.变量之间的转换将使系统的结构在方系统、胖系统和瘦系统之间发生转换.对于瘦系统,操作变量的维数少于被控变量,其控制效果往往低于其他结构的系统.同时,原操作变量不被控制器控制后,转换为前馈变量,也会影响对系统的控制效果.可行域能直接反映系统控制效果.在对状态空间模型进行多步预测推导的基础上,将部分控制变量与前馈变量进行转换,用空间几何映射表示变量转换,并分析转换对系统可行域的影响.最后,针对实际生产过程中放开部分控制变量的情况,提出预判机制,以保证系统可控.  相似文献   

10.
光伏系统的发电量受到太阳辐照强度、温度、湿度和压强等多种天气变量的影响,变化复杂,具有间歇性和波动性.传统预测模型中需要以天气预报数据作为输入,但其与实际的天气变量存在一定偏差,这给预测结果带来了不可避免的误差.为了进一步提高预测精度,本文提出了天气变量预测数据到天气变量实际数据和天气变量实际数据到光伏系统发电量的双模型预测系统,并对训练好的模型进行了测试和分析,预测结果表明,此模型能够达到较高的预测精度,具有一定的可行性和有效性.  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.
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   

19.
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   

20.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

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