面向全局的VVA体系结构研究

为了对建模与仿真进行全面性的校核、验证、确认(Verification,Validation,Accreditation,VVA),从系统工程的角度,提出了一种面向全局的VVA开放体系结构(VVA Global Open Structure,VVA-GOS),从通用性、生命周期及视图等方面对其内容、过程与方法进行了讨论,开发了VVA-GOS的基础平台.通过在水声对抗系统建模与仿真VVA中的应用,验证了VVA-GOS的可行性及有效性.为建模与仿真VVA提供了一个实用的体系结构和自动化的使能工具.图7,参12.     

数字仿真技术科学

数字仿真技术科学由其技术理论和专业技术两部分组成.技术理论是促进技术发展的理论.数字仿真技术理论指出,为了充分地发挥数字仿真的经济有效性,各仿真应用领域应按照"仿真需求-仿真系统-仿真应用"这个循环螺旋上升,最终达到面向整个领域的"三全":全寿命(包括论证、方案、研制、生产和使用等阶段),全系统(包括主要装备、支持装备、保障装备)和管理全方位.数字仿真专业技术主要密集在仿真系统,仿真软件,校核、验证和确认三大方面.三者相辅相成,缺一不可;三者共同构成了数字仿真区别于其它学科所独有的部分.如今,数字仿真的发展正在向数字化、智能化、虚拟化、集成化、网络化、协同化的方向大踏步地迈进.     

冷连轧轧制力仿真模型的可信度评估

根据仿真模型的校核、验证及验收理论和主要技术,结合冷连轧轧制过程的特点,对轧制力仿真模型的校核、验证和验收过程进行了简化.提出了适合轧制力仿真模型的可信度评估方法:不等式系数法与灵敏度分析法相结合的方法,即首先定义了仿真模型的TIC值,并用现场采集的轧制数据计算轧制力模型的TIC值,依据TIC值判断轧制力模型是否适合于当前的轧制条件,据此定性分析仿真模型的适用性;然后用灵敏度分析法定量分析仿真模型输入参数集对输出的敏感性,两种方法相辅相成,就能准确地验证轧制力模型的有效性.仿真实例与冷连轧生产线所采用的轧制力模型的实际情况相吻合.     

仿真技术在减速器设计中的应用

从齿轮传动的基本原理出发,系统地分析了齿轮传动系统的动力学模型,提出了基于齿轮副接触算法的动力学仿真模型.利用仿真软件建立了减速器虚拟样机模型,综合考虑了多种影响因素.计算结果很好地反应了实际的齿轮啮合接触行为,所使用的仿真方法及得到的分析结果对减速器的工程设计及性能校核具有参考价值和指导意义.     

船用柴油机均值模型建模及仿真研究

柴油机模型的研究是探究柴油机性能、实现虚拟仿真的基础,可缩短仿真计算时间、有效节约柴油机开发成本。本文以RK270柴油机为研究对象,使用GT-POWER软件建立稳态性能仿真模型,在此基础上,采用仿真精度高、计算速度快的平均值法,以C++语言建立柴油机平均值模型,并归纳通用的平均值模型建模标定校核流程;提出二元响应拟合的方法,解决了涡轮增压器特性参数处理困难的问题,并借助数学工具,获得了压气机主要工作区域内拟合精度较高的模型。完成模型开发后,分析了8组工况下的仿真结果,通过误差分析,验证了模型的准确性,丰富完善了柴油机建模理论和方法,可应用于实时控制模型的动态仿真或者实现与船舶动力系统的交互。     

基于改进SVPWM模型的异步电动机MRAS矢量控制

在分析SVPWM调制原理的基础上,对一种改进SVPWM的建模方法进行了详细研究.借助于Matlab强大的仿真建模能力,结合异步电动机MRAS矢量控制模型,建立了改进的仿真模型,并将其与SVPWM的一般仿真模型比较.仿真结果验证了改进的SVPWM仿真模型的正确性,与传统SVPWM相比结构简单,逻辑性强,运算量减少.     

基于IBIS模型的高速数字I／O缓冲器的瞬态行为建模

引入了一种基于最新版本的IBIS模型给出的信息构造高速数字I／O缓冲器的瞬态行为模型的方法，阐述了从IBIS建模数据中得到这种瞬时状态转换行为模型的过程，同时获得了建模所需要的充分条件，与相应的晶体管级模型相比，该方法在获得了更高仿真精度的同时，提高了具有大量同步开关器件芯片互连的仿真速度，最后，为了验证模型的有效性，给出了该模型和晶体管级模型（SPICE模型）模拟结果的比较。     

用于平顺性仿真的七自由度非线性模型

为了解决传统平顺性振动模型对悬架非线性环节描述不足的问题,开发了一个用于平顺性仿真的七自由度非线性时域模型.此模型以线性七自由度模型为基础,通过对悬架迟滞非线性和减振器非线性的准确建模,实现悬架非线性特性的准确描述.通过典型工况仿真,验证所建模型能够更为真实的描述悬架非线性环节对平顺性的恶化现象,进一步提升了平顺性模型的仿真精度.利用所建模型对影响平顺性的典型因素进行仿真研究,研究结果表明可以通过降低悬架刚度、合理匹配减振器阻尼等措施来提升平顺性.     

一种改进的耗散型接触力模型及实验验证

为了研究含间隙运动副对连杆机构动态性能的影响,基于能够描述碰撞过程中能量损失的连续接触模型,建立了一个新的耗散型接触力模型.在这个新模型下对含间隙连杆机构进行动力学仿真,并进行了实验研究.主要考察了间隙尺寸和加载强度对连杆受力的影响.结果表明:间隙的存在会影响传递力曲线,使机构产生明显的振动冲击,间隙大小和加载速度是影响机构动态响应的主要因素.该仿真结果得到了实验的验证.     

基于正过零鉴相的全数字锁相环的研究

介绍了数字锁相的主要方法,对正过零鉴相TMS320LF2407的全数字锁相环进行了数学建模,得到了简化模型.其模型对数字锁相环的参数设计有着非常重要的指导意义.仿真结果证明了该数字锁相环模型的可行性、稳定性与快速性.为提高数字锁相环的准确性,给出了处理量化误差的方法.     

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.     

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.     

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the