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 15 毫秒
1.
In the paper a concept for modeling the economic systems by the formalism of P?un’s systems is proposed. The main idea is to represent economic systems as homomorphic images of Petri nets corresponding to the (super) cells of P?un’s systems.  相似文献   

2.
In the paper a concept for modeling the economic systems by the formalism of P?un’s systems is proposed. The main idea is to represent economic systems as homomorphic images of Petri nets corresponding to the (super) cells of P?un’s systems.  相似文献   

3.
4.
    
Spatial analysis is a multidisciplinary field that involves multiple influential factors, variation and uncertainty, and modeling of geospatial data is a complex procedure affected by spatial context, mechanism and assumptions. In order to make spatial modeling easier, some scholars have suggested a lot of knowledge from exploratory data analysis (EDA), specification of the model, fitness and diagnosis of the model, to interpretation of the model. Also an amount of software has improved some functionalities of spatial analysis, e.g. EDA by the dynamic link (GeoDa) and robust statistical calculation (R). However, there are few programs for spatial analysis that can automatically deal with unstructured declarative issues and uncertainty in machine modeling using the domain knowledge. Under this context, this paper suggests a prototype support system for spatial analysis that can automatically use experience and knowledge from the experts to deal with complexity and uncertainty in modeling. The knowledge base component, as the major contribution of the system, in support of the expert system shell, codes and stores declarative modeling knowledge, e.g. spatial context, mechanisms and prior knowledge to deal with declarative issues during the modeling procedure. With the open architecture, the system integrates functionalities of other components, e.g. GIS’ visualization, DBMS, and robust calculation in an interactive environment. An application case of spatial sampling, design and implementation of spatial modeling with such a system is demonstrated.  相似文献   

5.
万新华  朱晓翠 《江西科学》2012,30(2):236-237,261
介绍了利用H.264 SVC可分级视频编码技术优势,有效地实现不同终端和网络用户的分级接入,确保不同网络和用户之间视频图像的流畅传输的实现方法。  相似文献   

6.
《科学通报(英文版)》1998,43(8):652-652
Molecular modeling of cyanoacrylates and ureas with D1 protein of Pisum sativum have been presented. Studies show that these two kinds of inhibitors occupy the similar region in the D1 protein. Cyanoacrylates have more binding sites than ureas, thus they have higher activities.  相似文献   

7.
The type III secretion system(T3SS) plays important roles in Pseudomonas aeruginosa pathogenicity.Previously,we reported that the uncharacterized protein PmpR could regulate pqsR,an important regulator in the quorum-sensing system,by directly binding to its promoter region.As the T3SS is controlled by the quorum-sensing system,here,we investigated the relationship between PmpR and the T3SS.Our data showed that expression of the T3SS genes exoS,exoY,exoT,and exsD was dramatically increased in a pmpR-deletion mutant compared with that in the wild-type P.aeruginosa strain PAO1.Data from DNA mobility assays indicated that PmpR affects the T3SS indirectly.It is unlikely that PmpR controls the T3SS via the Pseudomonas quinolone signal(PQS) because the PQS negatively regulates the T3SS,while pmpR negatively regulates the PQS.The effect of PmpR on the T3SS seems to be independent of the PQS;further investigation is required to uncover the underlying regulatory pathways.  相似文献   

8.
法藏写本P.2439保存完整,正面抄《萨婆多毗尼毗婆沙卷第三》,背面抄有杂写、《妙法莲华经》、社司转帖及《晏子赋》。从卷背题记可知该写本抄于924年,是一件与永安寺有关的写本。根据《晏子赋》异文情况,可知此卷所抄《晏子赋》与P.2564、BD10740属同一写本系统。  相似文献   

9.
房地产项目前期产品研发对项目开发价值的实现具有重要意义.通过对市场调研数据的回归分析,得到各种房地产产品的建筑密度、容积率、销售速度、销售均价的期望值,建立L.P.模型,定量地研究不同产品组合对地块价值的影响,这种方法基于已开发项目的客观数据,经过了市场的检验.有别于传统的对拟开发项目直接进行数据的假设.具有更高的科学性和合理性.  相似文献   

10.
谢剑峰 《广东科技》2008,(4):113-114
全文针对安全管理工作,结合“P.D.C.A.”戴明环的管理理念,从四个步骤重点介绍了提升电力施工单位安全管理水平的建议。  相似文献   

11.
通过对甘肃庆阳巴家嘴第四系底部地层中发现的2种真马化石研究得出,其地质年龄为2.5Ma B.P,是欧亚大陆发现最早真马化石的地点之一。认为:第四纪初真马从北美向欧亚大陆快速扩散的背景,是全球冰期气候的出现;中国与整个欧亚大陆一样,在一系列年龄为 2. 5 Ma B.P.的地点发现了最早的真马;这些化石显示出种级单元丰富的多样性,即在同一生态区域内常常同时有2种真马共同生活,还有三趾马共生;这是在气候突变条件下动物快速扩散事件产生的适应辐射,为区域叠覆成种理论提供了大型动物成种的证据。  相似文献   

12.
基于季节性AR(P)模型的水质预测   总被引:2,自引:0,他引:2  
自回归模型的建立是基于序列平稳性的假设,只能描述平稳序列的统计特性,而水质的月监测数据序列往往具有季节性变化的现象.文章介绍了平稳过程的相关理论及其检验方法并应用到黄河潼关、三门峡断面的水质序列的检验中,检验结果为非平穗序列,且序列具有明显季节性(月份)变化的特性。为此尝试建立季节性AR (P)模型来捕捉黄河水质的季节性变化规律,实践表明该模型预测总体效果是较为满意的。  相似文献   

13.
研究了Wolstenholme定理的逆命题,证明:若p∈P,2(?)p,2(?)t,n=prt,且t满足1/2pk<1/2p(k+1),2(?)k,则(2n-1 n)(?)(mod n3),即此时Wolstenholme定理的逆命题成立.  相似文献   

14.
Numerical modelling of a turbulent bluff-body flow has been performed using differential Reynolds stress models (DRSMs). To clarify the applicability of the existing DRSMs in this complex flow, several typical DRSMs, including LRR-IP model, JM model, SSG model, as well as a modified LRR-IP model, have been validated and evaluated. The performance difference between various DRSMs is quite significant. Most of the above mentioned DRSMs cannot provide overall satisfactory predictions for this challenging test case. Motivated by the deficiency of the existing approaches, a new modification of LRR-IP model has been proposed. A very significant improvement of the prediction of flow field is obtained.  相似文献   

15.
P.T.1047号写卷是国内外所藏敦煌古藏文文献中,篇幅最长、内容极其丰富且苦涩难懂又涉及吐蕃早期历史事件和历史人物的占卜类文书。文章认为该卜法属于中古苯教卜法,其产生年代很早,是藏族先民创造的非常古老的卜法之一,也是吐蕃王室或上层集团独享的一种占卜术。在其占卜的方式上,学界有木板上掷骰子法、羊胛骨卜法、象雄绳占法等三种不同的观点。但是通过文本研读发现,上述观点均经不起科学的检验,多为猜测或推断。另外,文章在前人研究的基础上,补偏救弊,翻译P.T.1047号全文的同时,做了必要的注解。  相似文献   

16.
英国浪漫主义诗人P·B.雪莱以抒情诗闻名于世,而《西风颂》是其著名抒情诗之一。本文把雪莱的《西风颂》的审美特征概括为:雄壮精妙。雄是指气势宏大,情感充沛;壮是指范围宽广,景色壮观;精是指刻画精致,描写细腻;妙是指含义深厚,哲理精妙。  相似文献   

17.
Based on the clonal selection theory and immune memory theory, a novel artificial immune system algorithm, immune memory clonal programming algorithm (IMCPA), is put forward. Using the theorem of Markov chain, it is proved that IMCPA is convergent. Compared with some other evolutionary programming algorithms (like Breeder genetic algorithm), IMCPA is shown to be an evolutionary strategy capable of solving complex machine learning tasks, like high-dimensional function optimization, which maintains the diversity of the population and avoids prematurity to some extent, and has a higher convergence speed.  相似文献   

18.
李霏  马玉贞 《甘肃科技》2007,23(3):99-102
文章在已有32-25 Ka B.P.期间黄土高原植被研究成果的基础上,初步勾画出黄土高原这一时期植被带的分布.与现今植被带分布相比,32-25 Ka B.P.期间森林草原带可能同时向南北扩张达到黄土高原的北界和南界,成为黄土高原植被的主体.现在兰州以西的草原带当时为山地针叶林.这些植被证据说明当时高原北部和西部可能比现在湿润,而南部比现在干.由于直接反映植被状况的资料有限,本文所进行的仅是定性的植被带描绘.  相似文献   

19.
This paper deals with the problem of robust H∞ control for uncertain systems with multiple state delays. The parameter uncertainties are unknown but norm - bounded. An LMI based method is developed for robust H∞ stabilization for a class of uncertain systems with multiple state delays via linear memoryless state feedback control. The resuits depend on the size of the delays and are given in terms of linear matrix inequalities, so they are less con. servative than those of delay - independent.  相似文献   

20.
IntroductionDetection of fecal coliforms,a group of bacteriaassociated with pathogens,has been used tomonitor the microbiological quality of water andfood for at least half a century. However,traditional methods are quite time- consuming,anddelays often occur in transporting samples fromfield to laboratory. Therefore,new portable andcompact instruments are needed.  Recently,β- D- galactosidase has often been usedas a coliform marker. Most current rapidtechniques are based on the enzymatic h…  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