基于区间多项式稳定性理论的PID控制器

为了研究热工过程鲁棒PID控制系统的分析和设计,针对具有参数不确定性的区间对象,根据Kharitonov定理及其广义定理,对PID控制系统的鲁棒性进行了分析,利用判断控制系统鲁棒性的充分条件、必要条件和充要条件,提出了一种针对区间对象进行鲁棒PID控制器设计和分析的方法和步骤。通过涡轮机负载的仿真控制实验,表明该方法在保证鲁棒性的同时,简化了分析和设计的计算量。     

基于PID控制的4工位冰箱性能测试试验室研制

介绍了PID控制技术在冰箱试验室的温湿度控制中的应用,依据国家标准GB／T8059．2-95要求,设计并建造了一套全自动电冰箱热工性能测试的试验系统,完成试验室空气处理系统、工况参数PID控制系统和电气系统设计以及软件编程等工作,并进行了调试电冰箱热工性能测试项目的试验。     

机炉协调控制的分散PID整定

设计适合于火电单元机组的机炉协调控制系统,有利于提高热工过程的自动化水平。采用双输入双输出(TITO)分散PID控制器的设计方法,应用于火电单元机组的机炉协调控制中,获得相应的控制系统。基于Nyquist稳定性判据和对角优势分析,通过适当的预补偿措施求得极限增益和极限频率,并利用Tyreus-Luyben方法整定PID控制器参数。通过仿真对比试验,显示了该控制系统具有满意的动态性能,以及较强的鲁棒性和抗干扰能力。     

基于MATLAB/Simulink环境下的PID参数整定

针对PID参数复杂烦琐的整定过程这一问题,基于MATLAB/Simulink仿真环境,模拟工程稳定边界法的PID参数整定策略和步骤,提出了一种简单有效的PID参数整定方法.与通常的整定方法比较,其优点是非常直观、完全可视化操作、省去了编程的工作量.仿真结果表明该方法具有良好的收敛性,使得控制系统动态性能得到有效改善,并且很大程度上减少了工作量.     

基于自适应遗传算法的PID参数寻优

针对工业过程中常见的二阶大滞后对象的PID参数调节问题,采用自适应遗传算法对PID控制进行参数寻优,并将结果与常用的PID参数寻优方法进行比较,仿真实验结果表明,在PID参数的寻优问题中,自适应遗传算法采用自动改变变异概率的方法,提高了控制系统的自适应性.     

基于自适应遗传算法的PID参数寻优

针对工业过程中常见的二阶大滞后对象的PID参数调节问题,采用自适应遗传算法对PID控制进行参数寻优,并将结果与常用的PID参数寻优方法进行比较,仿真实验结果表明,在PID参数的寻优问题中,自适应遗传算法采用自动改变变异概率的方法,提高了控制系统的自适应性。     

单元机组协调系统的非线性PID控制

协调系统的性能直接影响单元机组运行的安全性和经济性。设计有效的火电单元机组机炉协调控制系统是提高热工自动化水平的关键。首先介绍受控对象的数学模型及其简化的前提,然后采用双输入双输出(TITO)非线性PID控制器的设计方法,应用于火电单元机组的机炉协调控制中,获得相应的控制系统。利用Simulink工具箱中的NCD模块优化非线性PID控制器参数。通过仿真对比试验,显示了该控制系统具有优良的动态性能,以及较强的鲁棒性和抗干扰能力。     

模糊PID控制器在伺服变量泵控系统中的应用

针对伺服变量泵控制系统存在参数非线性、时变性等特点,基于模糊控制和PID控制理论,提出了模糊自适应PID控制方法来消除参数不确定性对系统控制性能的影响。仿真结果表明该控制策略有效提高了系统的响应时间,使系统具有良好的稳态性能和鲁棒性。     

基于模糊PID算法的直流电机控制系统研究

直流电机控制系统存在多变量,非线性,强耦合等特点。传统的PID控制存在其参数难以确定及PID参数对电机参数变化适应能力差等缺点。为克服上述缺点,本文根据模糊控制理论设计了基于模糊PID算法的直流电机双闭环调速控制系统;利用MATLAB软件对基于模糊PID控制的直流调速系统性能进行了仿真研究,并和传统PID控制系统进行了比较。仿真结果表明,和传统PID控制比较,模糊控制系统超调量小、抗扰动能力强、鲁棒性更高,更具适应性,控制性能优越。     

参数不确定对象的模糊非线性PID控制方法

针对传统 PID 控制不能同时获得较佳的动静态性能和一些非线性 PID 控制需构造合适的非线性函数和附加参数调整等问题,提出了将一维模糊控制器与 PID 控制器相级联构成了一个新型模糊非线性 PID 控制器。该一维模糊控制器只需用五条控制规则,实现了输入与输出的非线性增益关系,并且模糊非线性 PID 控制器利用原有的 PID 控制参数,易于实现。同时针对一类参数不确定的被控对象,采用基于蒙特卡罗方法进行随机试验得出了一种控制系统的性能评价方法     

Markedness and its Interpretation in Language Use

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.     

Features of Women's language

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

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.     

低渗透非均质砂岩油藏启动压力梯度研究

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

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.     

A computer generator for randomly layered structures

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

An Index mechanism for multi-scale view in spatial databases

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

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-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

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-