Exploring the Element Integration of Urban and Rural“Space of Flows”in the Context of Consumption Upgrading:A Case Study of Changsi Village in Anhui Province

The mobility and interaction between urban and rural areas are becoming more and more intensive,and their links and exchanges are increasingly closer due to constant flow of factors such as information,capital,personnel and technology.In this context,the element integration of urban and rural“space of flows”can promote the integrated development of urban and rural areas,improve the consumption environment and experience,and promote the industrial upgrading and technological progress.To realize the element integration of urban and rural“space of flows”,it is necessary to explore and innovate in infrastructure construction,information technology application,industrial cooperation and cultural exchanges.Government departments,enterprises and social organizations also need to work together to give play to their respective advantages and jointly promote the process of element integration of urban and rural“space of flows”.

非对比增强SPACE FLOW序列与CT静脉造影在髂静脉压迫综合征诊断中的对照研究

目的探讨非对比增强磁共振血管成像SPACE FLOW技术在髂静脉压迫综合征的临床应用价值。方法搜集临床上明确诊断髂静脉压迫综合征的患者64例,在进行下肢直接法CTV的前后2天内采用西门子Prisma 3.0T进行非对比增强磁共振血管检查,扫描序列包括True-fisp、T_(1) SPACE及SPACE FLOW。运用主观评分对比SPACE FLOW序列及下肢直接法CTV检查的图像质量;分别在两组图像上测量患侧髂总静脉最大受压处最短径、同层面对侧髂总静脉最短径、患侧髂总静脉远端最短径及对侧髂总静脉远端最短径,并根据1-(患侧髂总静脉最大受压处最短径/对侧髂总静脉远端最短径)计算出狭窄率,对比两组检查所得直径及狭窄率的差异;评价盆腔内侧支循环显示差异。结果两名医师对SPACE FLOW图像与下肢直接法CTV图像进行图像质量主观评分一致性良好,Kappa值分别为0.75和0.69,两种成像方式横轴位图像质量评分差异无统计学意义。SPACE FLOW在患侧髂总静脉最大受压处最短径值、同层面对侧髂总静脉最短径值、患侧髂总静脉远端最短径值及对侧髂总静脉远端最短径值均较CTV所测值低,差异均有统计学意义(P<0.05)。同时,两种方法测得的狭窄率不同,SPACE FLOW测得狭窄率(54.92±23.54)%较CTV测得狭窄率(51.45±21.94)%大,二者差异有统计学意义(P=0.017);运用Bland Altman图可见两组测量狭窄率一致性较好。SPACE FLOW盆腔侧支血管显示率与CTV相比有统计学差异(P<0.001);两种方法显示侧支循环一致性良好,Kappa值为0.620。结论SPACE FLOW序列对比下肢CTV在评价髂静脉狭窄程度的一致性高,显示侧支循环的一致性良好,可作为临床诊断髂静脉压迫综合征的另一种辅助检查方法。

Spatial Structure of China's E-commerce Express Logistics Network Based on Space of Flows

The intermediate link compression characteristics of e-commerce express logistics ne tworks influence the tradition al mode of circulation of goods and economic organization,and alter the city spatial pattern.Based on the theory of space of flows,this study adopts China Smart Logistics Network relational data to build China's e-commerce express logistics network and explore its spatial structure characteristics through social network analysis(SNA),the PageRank technique,and geospatial methods.The results are as follows:the network density is 0.9270,which is close to 1;hence,indicating that e-commerce express logistics lines between Chinese cities are nearly complete and they form a typical network structure,thereby eliminating fragmented spaces.Moreover,the average minimum number of edges is 1.1375,which indicates that the network has a small world effect and thus has a high flow efficiency of logistics elements.A significant hierarchical diffusion effect was observed in dominant flows with the highest edge weights.A diamond-structured network was formed with Shanghai,Guangzhou,Chongqing,and Beijing as the four core nodes.Other node cities with a large logistics scale and importance in the network are mainly located in the 19 city agglomerations of China,revealing the fact that the development of city agglomerations is essential for promoting the separation of experience space and changing the urban spatial pattern.This study enriches the theory of urban networks,reveals the flow laws of modern logistics elements,and encourages coordinated development of urban logistics.

磁共振T2-SPACE FLOW序列评价肺球形病灶内血管的可行性研究

目的探讨磁共振三维可变翻转角快速自旋回波成像技术(SPACE)在显示肺球形病灶内部血管的临床应用价值。方法搜集拟进行胸部CT增强扫描的患者30例,所有患者均在接受CT增强检查后24 h内进行MR检查。扫描序列包括T1WI 3D Star VIBE序列、T2WI HASTE序列以及T2-SPACE FLOW序列。由2名具有10年以上工作经验的放射科医师采用盲法先对MRI图像上所有病灶中肺血管的显示度进行主观评价,再观察与之对应的CT增强图像上肺血管的显示能力(CT增强图像作为参考标准),评分标准采用4分法(4分:边缘非常清晰,3分:边缘较清晰,2分:边缘不清晰,1分:不可见)。结果 CT增强图像上共检出48个肺球形病灶(大小1.0~5.6 cm),69支肺血管,另于MRI T2-SPACE FLOW序列上,检出48个球形病灶64支肺血管,检出率为94.3%。两名医师对CT增强图像和MRI图像上对肺球形病变内部血管形态显示度的主观评分分别为(3.59±0.46)分和(3.42±0.39)分(医师1)、(3.61±0.22)分和(3.49±0.68)分(医师2),差异均无统计学意义(P>0.05)。结论在显示肺球形病变内部血管中,T2-SPACE FLOW序列具有较高的敏感度及准确率,同时可以提供和CT增强扫描同等效能的肺血管显示度,具有重要的临床价值。

MICROGRAVITY EXPERIMENTS OF TWO-PHASE FLOW PATTERNS ABOARD MIR SPACE STATION

A first experimental study on two-phase how patterns at a long-term, steady microgravity condition was conducted on board the Russian Space Station 'MIR' in August 1999. Carbogal and air are used as the liquid and the gas phase, respectively. Bubble, slug, slug-annular transitional, and annular hows are observed. A new region of annular how with lower liquid superficial velocity is discovered, and the region of the slug-annular transitional flow is wider than that observed by experiments on board the parabolic aircraft. The main patterns are bubble, slug-annular transitional and annular flows based on the experiments on board MIR space station. Some influences on the two-phase how patterns in the present experiments are discussed.

LES prediction of space-time correlations in turbulent shear flows

We compare the space-time correlations calculated from direct numerical simulation （DNS） and large-eddy simulation （LES） of turbulent channel flows. It is found from the comparisons that the LES with an eddy-viscosity subgrid scale （SGS） model over-predicts the space-time corre- lations than the DNS. The overpredictions are further quantified by the integral scales of directional correlations and convection velocities. A physical argument for the overpre- diction is provided that the eddy-viscosity SGS model alone does not includes the backscatter effects although it correctly represents the energy dissipations of SGS motions. This argument is confirmed by the recently developed elliptic model for space-time correlations in turbulent shear flows. It suggests that enstrophy is crucial to the LES prediction of spacetime correlations. The random forcing models and stochastic SGS models are proposed to overcome the overpredictions on space-time correlations.

INVISCID INCOMPRESSIBLE AND COMPRESSIBLE FLOW EQUATIONS UNDER SPACE-TIME TRANSFORMATION

The equations governing incompressible and compressible inviscid flows and written in the physical frame ( t,x,y,z ) are known to be linearly well posed and exhibit elliptic or hyperbolic nature. The linear well posedness is considered here for these equations under a space time transformation ( t,x,y,z)→(τ,ξ,η,ζ ), where the pseudo time τ and the new space coordinate ( ξ,η,ζ ) all depend on ( t,x,y,z ). Such a transformation could be useful for uniformly treating problems in which the flow is fast unsteady somewhere and slow unsteady or steady elsewhere. It is found that the transformation may alter the ellipticity, the hyperbolicty, and even the well posedness of the original equations. In one dimension, the transformed incompressible flow equations become weakly hyperbolic and the compressible ones could degenerate to elliptical equations. In high dimensions there are conditions such that the transformed equations become ill posed.

Prediction of elevator traffic flow based on SVM and phase space reconstruction

To make elevator group control system better follow the change of elevator traffic flow (ETF) in order to adjust the control strategy,the prediction method of support vector machine (SVM) in combination with phase space reconstruction has been proposed for ETF.Firstly,the phase space reconstruction for elevator traffic flow time series (ETFTS) is processed.Secondly,the small data set method is applied to calculate the largest Lyapunov exponent to judge the chaotic property of ETF.Then prediction model of ETFTS based on SVM is founded.Finally,the method is applied to predict the time series for the incoming and outgoing passenger flow respectively using ETF data collected in some building.Meanwhile,it is compared with RBF neural network model.Simulation results show that the trend of factual traffic flow is better followed by predictive traffic flow.SVM algorithm has much better prediction performance.The fitting and prediction of ETF with better effect are realized.

Study of Nonlinear Earthquake Flow Functions and Their Application to the Space Increased Probability of Strong Earthquake (SIP)

The definition and abnormality discriminatory criteria of earthquake flow function are introduced in this paper based on the algorithm of Space Increased Probability (SIP). Nine earthquake flow functions were defined by the method. The retrospect test that applied the SIP algorithm with the nonlinear earthquake flow function to 7 earthquakes, which occurred from 1975 to 1989 in Eastern China, with a magnitude of 6 or greater depicted that 6 of the 7 strong earthquakes (86%) were located in the SIP areas, and the SIP covers about 32% of the total research time-space domain. These suggest that the R-value, an effective scale for earthquake forecast, is 54% and may imply that the nonlinear earthquake flow function introduced in this paper can be applied to the intermediate-term earthquake forecast research.

Formal Similarity of Solutions in the Laplace Space on the Class of Fluid Flow Differential Equation

In this paper, the fluid flow differential equation based on the homogenous reservoirs model is first reviewed. Then a theorem about the formal similarity of solutions in the Laplace space with outer boundary conditions and inner boundary condition is presented and proved. Lastly, a corollary of our theorem is given particularly on inner boundary. The obtained results are very helpful for understanding inherent laws of relevant engineering science and designing practical analysis software.

空间组织的逻辑演化与区域治理范式变革对中国城市群治理的启示

大都市作为区域发展的活跃力量和空间推进载体,是区域治理理论缘起与实践探索的重点,为城市群治理问题研究提供了价值基础。空间组织逻辑由“场所空间”向“流动空间”的转变形成了理论演化的分水岭,亦为区域治理理论奠定了贯通性的解释框架。在以信息城市为典型特征的“流动空间”背景下,区域治理思维发生了向新区域主义理论强调关系协调的非制度性变革和新国家空间理论围绕“再地域化”的制度变革的范式变化。后者重点阐释了全球城市区域崛起并充当国家竞争力平台的尺度重组机制,对沿海城市群完善制度建设具有重要的指导价值。前者关于区域整体性的建构思路对后发城市群的发育壮大仍然不乏实践意义。在中国多重尺度嵌套的复杂空间格局下,采取正式与非正式制度变革互补的城市群治理策略是可行的选择,对创新网络的尺度重组则是未来区域治理的重点。

Space Transformation-Based Interdependency Modelling for Probabilistic Load Flow Analysis of Power Systems

Dependence among random input variables affects importantly the results of probabilistic load flow(PLF),system economic operation,and system security.To solve this problem,the main objectiveness of the paper is to analyze the performance of several schemes for simulating correlated variables combined with the point estimate method(PEM).Unlike the existing works that considering one single scheme combined with Monte Carlo simulation(MCS) or PEM,by neglecting the correlation among random input variables,four schemes were presented for disposing the dependence of correlated random variables,including Nataf transformation /polynomial normal transformation(PINT) combined with orthogonal transformation(OT) / elementary transformation(ET).Combining with the 2m+1 approach of PEM,a space transformation-based formulation was proposed and adopted for solving the PLF.The proposed approach is applied in the modified IEEE 30-bus system while considering correlated wind generations and load demands.Numerical results show the effectiveness of the proposed approach compared with those obtained from the MCS.Results also show that the scheme of combining Nataf transformation and ET with PEM provides the best performance.

对置射流封闭人居空间内流场的涡识别研究

在由多个对置射流风口所构成的封闭人居环境内,对涡旋结构的认识对遏制病毒和污染物传播起到至关重要的作用。搭建了对置射流封闭人居空间的缩比模型,使用PIV(particle image velocimetry)系统对等温条件和冷却条件下的流场进行测量。在涡的视角下对流场的湍流特性进行研究,对比了不同的涡识别算法的识别效果。筛选出Liutex涡识别方法对一个摆动周期内的涡旋运动进行分析,发现逆时针和顺时针方向涡旋强度不同,最大强度分别为50 s^(-1)和110 s^(-1),得出涡旋的运动、合并、湮灭会对流场结构产生影响,射流摆动的周期约为3.67 s。由于涡对污染物具有锁定作用,通过涡心相对频率分布图表示污染物聚集的区域,分析得出虽然流场是非定常的,但涡的分布却相对稳定,其中CS4截面左侧涡心在同一点出现的次数高达21次。在冷却条件下污染物被锁定在更小的区域,这有助于遏制污染物的传播。

Space Syntax与Arc GIS集成技术下的商业体内行人轨迹预测

为有效地开展空间使用价值预测及人流预测,研究了建筑空间组织对人流分布的影响.以商业建筑为研究类型,选择两个典型样本,综合Space Syntax与Arc GIS集成技术对集销中心交通空间进行量化分析.该技术在建立理论与现实之间的反馈机制方面具有独特优势,研究数据表明:对于业种组合稳定的集销中心,可综合主入口位置、垂直交通布局与空间整合度等因素实现建筑内有效的人流分布预测;合理的垂直交通与业种分层组合有利于提高各层人流的可达性;集销中心内部空间均具有较强的对称性,其组构关系越简明、形态越统一,越利于实现人流均衡分布.

Flow-shop网络作业计划模型的解法

将 Flow-Shop网络作业计划的优化模型 Sch( m,n) Lp[1 ] 化为向量矩阵线性空间 ,利用线性空间的理论提出了一个求解

一种保持OpenFlow功能完整性的TCAM流表压缩模型

OpenFlow协议版本的更新带来流表项匹配域支持字段的增加,而表项匹配域支持的任意通配符依赖TCAM进行匹配处理,导致设备中的TCAM存储空间面临很大压力。为此,提出一种减小TCAM中流表存储空间的数学模型FICO(function-integral TCAM-saving compression model for flow table of OpenFlow)。FICO首先根据匹配域不同字段间的关系,将字段之间的冗余分为三种,基于冗余提出三种预压缩算法,分别为域间字段合并、字段映射、域内字段压缩,最终组合为更小位宽的表项被送往TCAM中进行流匹配。通过仿真表明在保持OpenFlow功能完整性的前提下,较未压缩流表,FICO可以节省60%TCAM存储空间。并且随着流表规模的增大,压缩性能保持稳定。

一种抗恶意攻击的OpenFlow虚拟流表高性能查找方法

针对恶意攻击给OpenFlow虚拟流表查找带来的破坏性影响,构建了一种抗恶意攻击的OpenFlow虚拟流表高性能查找方法。该方法基于近似成员关系查询理论,采用布鲁姆过滤器预测元组查找失败结果,以绕过绝大多数元组失败查找操作,提高OpenFlow虚拟流表查找效率;进一步,设计了一种可扩展计数型布鲁姆过滤器,根据元组规模的动态变化进行适应性伸缩,从而始终以高准确率判定元组查找失败结果;最后,采用实际网络流量样本和模拟恶意攻击方式,评估所提OpenFlow虚拟流表查找方法的性能。实验结果表明:当攻击包与正常包分别按1:2和2:1比例混合时,所提方法的假阳性错误率始终保持在6%以下,比计数型布鲁姆过滤器降低了93%,而平均查找长度降低了90%。

直管型不锈钢板式热沉流动与传热数值模拟

热沉主要用于在空间环境试验中模拟太空冷黑环境,针对现有蜂窝型板式热沉存在的流阻大、极易产生气堵的问题,提出采用直管型不锈钢板式热沉结构,对其流体分布与温度分布进行了仿真研究,使用液氮作为工质,研究了热流、流速、单管流道宽度、管道间距等参数对温度、流体分布及流阻等的影响。

TIME-SPACE CONCEPT FOR PRECISION MEASUREMENT

The transformation between time and space is discussed. To improve real-time response speed of intelligent measuring system, the concept of exchanging program execution time with more circuitry is presented working in cycle mode. Displacement measuring by magnification is achieved with period measurement by magnification. To change the condition that traditional precision measurement depends on machining precision greatly, the concept of measuring space with time and theory of time-space coordinate transformation are proposed. Guided by the idea of measuring space with time, differential frequency measurement system and time grating displacement sensor are developed based on the proposed novel methods. And high-precision measurement is achieved without high-precision manufacture, which embeds the remarkable characteristics of low cost but high precision to the devices. Experiment and test results conform the validity of the proposed time-space concept.

Aerodynamic map for soft and hard hypersonic level flight in near space

In this note, we design a velocity-altitude map for hypersonic level flight in near space of altitude 20-100 km. This map displays aerodynamic-related parameters associated with near space level flight, schematically or quantitatively. Various physical conditions for the near-space level flight are then characterized, including laminar or turbulent flow, rarefaction or continuous flow, aerodynamic heating, as well as conditions for sustaining level flight with and without orbital effect. This map allows one to identify conditions to have soft flight or hard flight, and this identification would be helpful for making correct planning on detailed studies of aerodynamics or making initial design of near space vehicles.