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1.
将各种排放物影响因子进行分类后 ,应用灰色系统理论 ,提出了影响评估灰类划分及其白化权函数 ,对各影响类别进行了灰色聚类分析 ,而后根据分析结果给出了分类影响指数的计算方法 .根据各影响类别的作用范围 ,将影响类别按全球影响、区域影响、本地影响进行了分组 ,并给出了分组影响指数以及总体影响指数的计算方法 .最后 ,以设计中的材料选择为例 ,说明了该方法在一类产品比较选择中的应用 .  相似文献   

2.
介绍了科技期刊影响因子的概念,分析了影响科技期刊影响因子的主要因素,提出了提高科技期刊影响因子的有效途径。  相似文献   

3.
刘天能 《科技信息》2009,(12):43-44
大学生就业难受多种因素影响,其成因的复杂性决定了就业难问题的解决是一项长期工程。本文从系统的角度,分析了影响大学生就业的因素。通过对影响大学生就业的五个影响体的分析,构建了就业影响系统模型,并提出了相应对策。  相似文献   

4.
随机约束条件下线性回归模型中的联合影响   总被引:1,自引:0,他引:1  
本文讨论数据集对约束模型的影响问题。建立了单组数据影响与两组数据影响之间的关系。引进了一个新的影响度量,并和Cook距离做了比较。  相似文献   

5.
大学生就业难的系统思考   总被引:1,自引:0,他引:1  
大学生就业难受多种因素影响,其成因的复杂性决定了就业难问题的解决是一项长期工程。本文从系统的角度,分析了影响大学生就业的因素。通过对影响大学生就业的五个影响体的分析,构建了就业影响系统模型,并提出了相应对策。  相似文献   

6.
城市内涝问题成为摆在我国城市发展面前的一个重要问题,低影响开发技术为解决城市内涝问题提供了有力的措施。解释了低影响开发技术的概念,分析了低影响开发技术对解决城市内涝问题的影响,评价了低影响开发技术的应用效果,阐述了低影响开发技术理论与方法的主要缺陷与扩展方向。  相似文献   

7.
陈一搏 《科技资讯》2013,(6):146-146
水力发电的出现缓解了城市用电紧张的局面,但在另一方面也给生态环境带来了一定的影响,这种影响既有正面影响也有负面影响。对于正面影响应该加以利用,而对于负面影响应该寻找解决办法降低危害性或消除影响因素。本文主要阐述了水力发电开发对生态环境造成的影响,也表明了加快水力发电发展的重要性。  相似文献   

8.
单位宽度轧制力对热轧带钢凸度的影响规律   总被引:1,自引:1,他引:1  
为了建立高精度的热轧带钢凸度计算数学模型 ,根据带钢凸度计算理论 ,采用影响函数法开发了四辊轧机带钢凸度影响率计算软件 ,系统地分析了单位宽度轧制力、轧辊直径和压下量对单位宽度轧制力影响率的影响规律·结果表明单位宽度轧制力影响率随带钢宽度的增加呈抛物线变化 ;轧辊直径和压下量对单位宽度轧制力影响率有一定的影响 ;建立了高精度单位宽度轧制力影响率的数学模型 ,确定了单位宽度轧制力影响率基本值及工作辊直径、支撑辊直径、压下量对单位宽度轧制力影响率修正系数的 6次拟合系数 ,为板形控制系统模型的建立及参数优化提供了理论依据  相似文献   

9.
影响因子对科技期刊评价的客观性分析   总被引:2,自引:0,他引:2  
论述了影响因子及其IF值的影响因素,分析了诸多因素对影响因子的影响,进而认为在对科技期刊评价中应该科学使用影响因子与科技期刊评价系统中提供的各项硬性学术计量指标.  相似文献   

10.
介绍了DG对继电保护生成影响的原因,且对其三个方面影响进行了简要描述:孤岛及对自动重合闸产生的影响、对故障电流产生的影响、对线路保护产生的影响。  相似文献   

11.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

12.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

13.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

14.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

15.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

16.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

17.
18.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

19.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

20.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

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