Functionality Semantics of Predicate Data Flow Diagram

SOZL (structured methodology + object-oriented methodology + Z language) is a language that attempts to integrate structured method, object-oriented method and formal method. The core of this language is predicate data flow diagram (PDFD). In order to eliminate the ambiguity of predicate data flow diagrams and their associated textual specifications, a formalization of the syntax and semantics of predicate data flow diagrams is necessary. In this paper we use Z notation to define an abstract syntax and the related structural constraints for the PDFD notation, and provide it with an axiomatic semantics based on the concept of data availability and functionality of predicate operation. Finally, an example is given to establish functionality consistent decomposition on hierarchical PDFD (HPDFD).

A New Synthetical Knowledge Representation Model and Its Application in Data Flow Diagram

A new synthetical knowledge representation model that integrates the attribute grammar model with the semantic network model was presented. The model mainly uses symbols of attribute grammar to establish a set of syntax and semantic rules suitable for a semantic network. Based on the model,the paper introduces a formal method defining data flow diagrams (DFD) and also simply explains how to use the method.

Tectonic Implications of the Combined Use of Tectonomagmatic Geochemical Discrimination Diagrams and Indicators of Magma Flow Sense in Mafic Dykes

Geochemistry is a powerful tool to help characterize the tectonic setting of igneous rocks associations.However,when continental mafic dykes and flood basalts are the target most of the proposed geochemical discrimination diagrams fail to correctly classify them,i.e.many mafic

DFDVis:A Visual Analytics System for Understanding the Semantics of Data Flow Diagram

Data flow diagram(DFD),as a special kind of data,is a design artifact in both requirement analysis and structured analysis in software development.However,rigorous analysis of DFD requires a formal semantics.Formal representation of DFD and its formal semantics will help to reduce inconsistencies and confusion.The logical structure of DFD can be described using formalism of Calculus of Communicating System(CCS).With a finite number of states based on CCS,state space methods will help a lot in analysis and verification of the behavior of the systems.But the number of states of even a relatively small system is often very great that is called state explosion.In this paper,we present a visual system which combines Formal methods and visualization techniques so as to help the researchers to understand and analyze the system described by the DFD regardless of the problem of state explosion.

基于系统动力学模型的医院舆情风险研究

目的应用系统动力学模型探讨医院舆情风险系统的作用力,为医院舆情管理提供参考。方法构建医院舆情风险的因果回路图和存量流量图,结合案例舆情事件设定模型的方程和参数,应用Vensim PLE软件模拟仿真。结果医院子系统和政府子系统的作用变量分别增加10%,都会降低医院舆情风险,其中政府作用力更强,“峰值到消退阶段”比“起始到峰值阶段”作用更明显。将系统5个流量变量分别增加10%后比较舆情风险的变化,在舆情起始和发展阶段,事件作用力最大,其次是网媒和医院的作用力;在舆情峰值和消退阶段,政府作用力最大,其次是网媒和医院的作用力。结论在舆情起始阶段,医院应侧重事件主体,将舆情控制在初始萌芽状态;在发展和峰值阶段,医院应有效回应,表明态度,澄清事实,提倡政府适时介入,降低舆情热度,维护社会稳定;在消退阶段,医院应利用事件余热进行形象重塑。

Anisotropic flow in high baryon density region

Collective flow is a powerful tool used to analyze the properties of a medium created during high-energy nuclear collisions.Here,we report a systematic study of the first two Fourier coefficients v_(1)and v_(2)of the proton andπ^(+)from Au+Au collisions in the energy range√sNN=2.11-4.9 GeV within the framework of a hadronic transport model(UrQMD).Recent results from the STAR experiment were used to test the model calculations.A meanfield mode with strong repulsive interaction is needed to reproduce the 10-40%data at 3 GeV.This implies that hadronic interactions play an important role in the collective flow development in the high baryon density region.The mean values of the freeze-out time for protons andπ^(+)are shifted earlier owing to the additional repulsive interactions.We predict the energy dependence of the mean values of the transverse momentum<pT>,v_(1),and v_(2)for both protons andπ^(+)from the Au+Au collisions.

Analysis of interrelationship between pedestrian flow parameters using artificial neural network

Pedestrian flow parameters are analysed in this study considering linear and non-linear relationships between stream flow parameters using conventional and soft computing approach. Speed-density relationship serves as a fundamental relationship, Single-regime con- cepts and deterministic models like Greenshield and Underwood were applied in the study to describe bidirec- tional flow characteristics on sidewalks and carriageways around transport terminals in India. Artificial Neural Net- work （ANN） approach is also used for traffic flow mod- elling to build a relationship between different pedestrian flow parameters. A non-linear model based on ANN is suggested and compared with the other deterministic models. Out of the aforesaid models, ANN model demonstrated good results based on accuracy measure- ment. Also these ANN models have an advantage in terms of their self-processing and intelligent behaviour. Flow parameters are estimated by ANN model using MFD （Macroscopic Fundamental Diagram）. Estimated mean absolute error （MAE） and root mean square error （RMSE）values for the best fitted ANN model are 3.83 and 4.73 m/ min, respectively, less than those for the other models for sidewalk movement. Further estimated MAE and RMSE values of ANN model for carriageway movement are 4.02 and 4.98 m/min, respectively, which are comparatively less than those of the other models. ANN model gives better performance in fitness of model and future prediction of flow parameters. Also when using linear regression model between observed and estimated values for speed and flow parameters, performance of ANN model gives better fitness to predict data as compared to deterministic model. R value for speed data prediction is 0.756 and for flow data pre- diction is 0.997 using ANN model at sidewalk movement around transport terminal.

Application and comparison of coaxial correlation diagram and hydrological model for reconstructing flood series under human disturbance

Intense human activities have greatly changed the flood generation conditions in most areas of the world, and have destroyed the consistency in the annual flood peak and volume series. For design flood estimation, coaxial correlation diagram and conceptual hydrological model are two frequently used tools to adjust and reconstruct the flood series under human disturbance. This study took a typical mountain catchment of the Haihe River Basin as an example to investigate the effects of human activities on flood regime and to compare and assess the two adjustment methods. The main purpose is to construct a conceptual hydrological model which can incorporate the effects of human activities. The results show that the coaxial correlation diagram is simple and widely-used, but can only adjust the time series of total flood volumes. Therefore, it is only applicable under certain conditions(e.g. There is a strong link between the flood peaks and volumes and the link is not significantly affected by human activities). The conceptual model is a powerful tool to adjust the time series of both flood peak flows and flood volumes over different durations provided that it is closely related to the catchment hydrological characteristics, specifically accounting for the effects of human activities, and incorporating expert knowledge when estimating or calibrating parameters. It is suggested that the two methods should be used together to cross check each other.

Study of shear-thinning/thickening effects on plane Couette-Poiseuille flow with uniform crossflow

The shear-thinning/thickening effects on the plane Couette-Poiseuille flow with a uniform crossflow are studied. The detailed solution procedures for both theo- retical and numerical purposes are given. In order to clarify the difference between the Newtonian flow and the power-law flow, all cases of the plane Couette-Poiseuille flows with uniform crossflows for different power indexes are assigned to the phase diagram in the parameter plane corresponding to the Couette number and the crossflow Reynolds number. The effects of shear-thinning/thickening on the phase diagram are discussed. An important feature of the shear-thinning circumstance distinguished from the shear- thickening circumstance is discovered.

Process-Based Friction Factor for Pipe Flow

The Moody Diagram is widely used to determine the friction factor for fluid flow in pipes. The diagram combines the effects of Reynolds number and relative roughness to determine the friction factor. The relationship is highly non-linear and appears to have a complex interaction between viscous and boundary roughness effects. The Moody Diagram is based on predictions from an equation developed by Colebrook in 1939. The relationship requires an iteration process to make predictions. While empirical relationships have been developed that provide good predictions without an iteration process, no one has fully explained the cause for the observed results. The objective of this paper is to present a logical development for prediction of the friction factor. An equation has been developed that models the summed effect of both the laminar sublayer and the boundary roughness on the fluid profile and the resulting friction factor for pipes. The new equation does not require an iteration procedure to obtain values for the friction factor. Predicted results match well with values generated from Colebrook’s work that is expressed in the Moody Diagram. Predictions are within one percent of Colebrook values and generally less than 0.3 percent error from his values. The development provides insight to how processes operating at the boundary cause the friction factor to change.

汽车发电机支架压铸模设计及成型工艺优化

针对汽车发电机支架结构特点及品质要求高等问题,运用PQ2图优化电机支架压铸模设计,应用UG、FLOW-3D软件进行有限元模型的建立、模拟分析,预测铸件内部出现气孔、缩孔缺陷问题,优化发电机支架压铸成型工艺。通过对模具设计及压铸工艺的优化,进行生产并对生产的发电机支架铸件进行X射线探伤检测及精加工。结果表明,通过PQ2图优化模具设计及FLOW-3D优化压铸成型工艺,有效预防了发电机支架压铸成型缺陷产生,提升了铸件品质的同时又缩短了产品开发生产周期。

电网潮流图T接点及线路自动生成研究与应用

为了解决110 kV电网中存在大量T接线路,而潮流图中无法展示T接线路从而给电网实时监控造成很大困难的问题,提出一种电网潮流图中T接站及其线路的辅助生成方法,分析T接间隔下的线路连接关系,在常规厂站联络线布局的基础上,叠加生成T接点及其联络线。研究结果表明,该方法稳定可靠,在多个地级电网调度中心得到了实际应用。

基于开关流图法的Buck-Boost变换器小信号建模分析

阐述Buck-Boost变换器具有输出纹波低,电压可控等优点,广泛应用于新能源汽车电池发电、直流微电网。建立小信号模型有利于对电路系统主电路的控制和控制回路的设计。分析Buck-Boost变换器,利用开关流图法和信号支路的模型建立变换器的流图,从而推导出变换器的小型号模型。

基于宏观基本图的交通控制有效性与路网稳定性研究

区域城市路网在不同控制方法下呈现的网络交通流输出水平与维持能力不尽相同,要评价控制效果的优劣,需要分析区域控制方式下路网交通流与路网耦合时所体现出来的特征值。作为一种路网的基本属性,选择宏观基本图作为研究区域交通控制有效性与路网稳定性的评价载体,解析了相对于路段、交叉口等单点评价具有的优势。基于MFD的区域交通控制评价不受路网交通需求变化的影响。研究建立了路网最大加权流量、最佳累计车辆数、路网负载能力、交通流分布均衡度以及时序均衡度5评价指标,以对区域交通信号控制方法的有效性与路网运行的稳定性进行评价,解读路网高峰时段的交通流维持能力。以成都青羊区太升南路附近37个信号交叉口为路网,利用VISSIM二次开发技术,获得了该路网在定时控制、感应控制、自适应控制以及自适应协调控制下的路网宏观基本图形态。通过对比各控制方法的宏观基本图形态特征与评价指标,从多个维度比较了各控制方法的特征与适用性,分析了相应的控制有效性,解读了其从平峰至过饱和各阶段的交通流维持能力,进而可以了解特定控制方法下路网的运行效率。同时,根据相应控制方法的稳定性表现,指出了各自的局限性,有助于在实际应用中根据区域路网面临的环境,分析应采取的交通控制策略。

自然循环锅炉深度调峰时水冷壁汽水两相流动不稳定特性计算及安全分析

为对深度调峰时对冲燃烧自然循环锅炉水冷壁管道内的汽液两相流动不稳定特性进行研究,建立了适用于不同工况的频域法数学模型。通过对质量、能量、动量方程进行小扰动线性化,消去高阶无穷小扰动量以及稳态量后经拉普拉斯变换得到了用于描述管道内汽液流体流动稳定性传递函数,通过Nyquist曲线图解的方法判断管内工质流动的稳定性。计算结果表明典型回路在25%BMCR和50%BMCR工况运行时的临界热流密度分别为182.20、240.13k W/m^(2)。同时,利用该模型计算了某350MW自然循环锅炉水冷壁管段的不稳定边界并研究了入口过冷度、质量流速、管长、倾斜角度以及入口节流系数等参数对流动不稳定特性的影响。计算结果表明:入口过冷度对临界热流密度的影响呈非单值性,不稳定边界图表现为“双C”型;增大质量流速使流体的进口和出口密度差减小,有利于流动的稳定;增大热流密度使流体的进口和出口密度差增大,不利于流动的稳定;增大入口节流系数,可以抑制入口处流量的脉动,有利于流动的稳定;增加管道的倾斜角度,会增大重位压降,使其产生的扰动增加,不利于流动的稳定。

基于CRCLA的形式化描述与退火遗传映射算法

为解决密码算法映射到粗粒度可重构密码逻辑阵列(CRCLA)过程的描述困难问题,提出一种数据流图节点与划分后节点簇的描述形式,并以一种坐标序列描述形式精确显示CRCLA中资源的占用情况;针对密码算法映射到CRCLA上性能不高及编译时间过长的问题,提出一种能快速收敛到全局最优解的退火遗传算法,从初始温度、降温系数等方面对退火算法进行改进,增加遗传算法的筛选、交叉与变异流程。实验结果表明,编译时间与性能平均降低了30.6%与13.4%,验证了算法的高能效映射。

中国能源系统能流、㶲流与能效分析

能源领域贡献了中国近90%的碳排放,对能源系统能流与能效的多维刻画及分析对碳中和路径的顶层设计具有极其重要的作用。能量具有“数量”与“品质”的双重属性,将能量的数量分析法和品质分析法相结合,分别从热力学第一定律能流和热力学第二定律㶲流的视角,研究并刻画了2010年和2020年中国能源系统的能流图和㶲流图。并从能源生产、加工、转换、消费等角度,对比分析了中国能源系统能源各链条能流、能效与损失的特征。发现2010年和2020年中国终端能源效率从74.52%提升至79.04%,同时能源结构向绿色低碳转型。但同期中国能源系统的㶲效率仅分别为17.44%和23.91%,能源转换的㶲损失仍较大,存在大量的电能低质利用、热能不匹配利用、能源原料燃烧利用等过程。最后,就双碳目标下中国能源效率从能流视角走向㶲流视角的提出了相关建议。

基于多普勒超声技术的中医脉象鉴别指标筛选

目的 探索基于多普勒超声技术的中医脉象表达规律,筛选可用于脉象鉴别的多普勒超声血流频谱图指标。方法 利用彩色多普勒超声诊断仪收集临床常见脉象平脉、浮脉、沉脉、弦脉、滑脉、弱脉、涩脉数据信息,比较分析平脉与浮、沉、弦、滑、弱、涩脉之间的差异,筛选可作为脉象鉴别的多普勒超声血流频谱图指标。结果 收缩期峰值血流速度(PS)、舒张末期血流速度(ED)、收缩期峰值血流速度/舒张末期血流速度(S/D)、收缩期峰值血流速度-舒张末期血流速度(PS-ED)、阻力指数(RI)、收缩期主峰加速度(V1)、收缩期主峰减速度(V2)、收缩期升支角度、收缩期降支角度、收缩期降支角度-升支角度、平均血流速度(V3)、搏动指数(PI)、灰度值最大值、灰度值平均值、灰度值中间值、一周期面积、收缩末期血流速度等指标可以作为脉象鉴别指标。结论 利用彩色多普勒超声进行脉象的客观化表达研究具有可行性,共筛选出彩色多普勒超声脉象鉴别指标17个。

船舶交通流速度离散特性研究

为更深刻地理解船舶交通流运行特性,以速度离散度研究为切入点,提出描述船舶交通流速度离散特性的两种指标,根据交通流基本图理论,对速度离散度在船舶交通流基本图上的分布及其与船舶交通流三参数之间的关系进行定量分析。结果表明:随着船舶流量、密度和速度的增加,速度离散度的分布趋于稳定,在低流量、高速度离散度区间内,速度离散度随着船舶流量的增加逐渐降低,在低速度离散度区间内,速度离散度随着船舶流量增加逐渐升高;基于改进的K-means-FCM算法,使用船舶交通流流量、密度、速度和速度离散度作为分类指标,对船舶交通流进行聚类分析,得到4个聚类中心与指标值的分布范围。基于试验结果,抽象总结船舶交通流运行状态图,将船舶交通流划分自由态、同质态、稳定态和异质态等4种状态。该研究对更好地认识船舶交通流特性起到一定的作用。

基于能流和碳流的文成县低碳发展路径研究

针对我国各地开展精细化碳流分析的需求,提出了一种符合我国能源结构、能够快速精细分析的能源电力分析模型和碳分析模型,并提出了相应的构建计算方法,实现了对煤炭、石油、天然气等化石能源和光伏、风电、核电等清洁发电的全覆盖。以文成县为典型案例,基于能流和碳流模型,依据能源供给、能源传输、能源消费等数据信息分析了文成县的能源系统,并从碳排放总量、碳排放结构、碳排放强度和碳排放趋势方面构建文成县全域的碳排放流。通过量化能源传输和消费过程中的碳流情况,直观展现文成县能源结构和碳排情况,并提出了文成县未来低碳发展路径。分析结果表明,文成县处于“负碳”状态,产业碳排放承载空间和终端电力替换空间巨大,亟待建立配套机制,发挥碳资产资源优势。实际案例证明了能流和碳流模型能够快速完成地区能流碳流的精细化分析,有力支撑地方双碳规划。