基于协流结构的区域经济系统建模与政策仿真

使用协流结构构建经济系统动力学模型,合乎经济学相关理论的一般逻辑,可以为产业结构政策的仿真分析带来便利.模型应用的仿真研究表明,我国先发展地区的经济服务化转型,应该采取"进三升二"的发展路径,一方面要加快产业升级,推动制造业的先进化、高端化;另一方面,要大力发展现代服务业和高新技术产业,构建"双轮驱动"的现代产业体系.

基于增量聚类的协流识别系统研究

云计算中的群集计算应用程序(例如Map Reduce和面向用户的应用程序)具有应用程序级别的需求,因此需要有高级别的抽象来表示这些应用程序的需求.协流(coflow)是一个网络级别的抽象,用来表达数据并行编程范例的通信要求.协流使应用程序更容易地将其通信语义传达给网络,从而使网络能够优化常见的通信模式.然而,现有的协流识别方案依赖于修改应用程序,并不适用于多数实际场景.提出了基于增量聚类的协流识别策略,采用增量聚类算法来执行快速、透明的协流识别,实现了协流识别的自动化,同时无需对应用进行修改.仿真实验结果显示,本文的识别算法具有超过90%的准确率,具有一定的鲁棒性.

水雾协流作用下甲烷层流预混火焰熄火规律

在自行研制的水雾协流管式燃烧器的基础上,利用高速纹影实验系统对水雾协流作用下层流预混火焰燃烧速度、火焰拉伸以及熄火规律进行了实验研究,分析其现象产生过程与机理,得到了不同浓度甲烷预混火焰临界熄火时火焰拉伸率与燃烧速度的变化规律.结果表明,管式燃烧器预混火焰面拉伸与燃料浓度、混合气体流量以及水雾雾滴直径有关;对于较大粒径的细水雾,水雾载荷比越小,火焰面拉伸现象越明显;Le>1的富燃料预混火焰,当水雾载荷比较小时,燃烧速度越大的预混火焰更容易发生回火;而Le<1的贫燃料预混火焰,在相同水雾条件下,预混气体浓度越小,火焰就越容易产生熄脱.

燃料射流与空气协流混合中的自点火预测研究

预混燃烧室燃料与空气混合过程中出现的自点火会引起回火与挂火,烧毁燃料喷嘴。针对这一问题,利用实验台模拟贫燃燃烧室预混过程,燃料射流与预热后的空气协流同向喷入石英管预混段中,研究自点火现象。本文结合机器学习和物理规律分析,开展湍流混合过程的自点火预测研究。基于二元逻辑回归建立了机器学习模型,模型的特征由分析影响自点火的物理规律得到,训练和校验模型所需的数据由燃料射流-空气协流的自点火实验获得。结果显示,机器学习方法能快速、准确地预测混合过程中自点火的发生和火焰类型,并揭示其关键影响因素。与传统的数值计算方法相比,机器学习方法预测自点火所需的时间仅为传统数值模拟方法的几千分之一。

火焰羽流区细水雾利用效率及控制研究

为提高细水雾的灭火效能,研究细水雾对火焰的冷却性能。建立火焰区细水雾的运动、传热与传质模型,采用此模型全面评估影响细水雾穿透距离和汽化性能的因素,提出一种合理确定液滴初始粒径和初始速度的方法,以及能够提高细水雾利用效率的射流协流细水雾系统。结果表明:各因素影响作用由大至小排序为液滴初始粒径、传热温差、液滴初始速度、火焰羽流速度;该系统能够显著提高细水雾的穿透距离,增大细水雾的汽化率。

高温逆气流中细水雾的行为与控制研究

为提高细水雾的穿透性能,研究高温逆气流中细水雾的行为,建立单个雾滴运动、传热模型,分析逆气流和高温对雾滴速度和穿透距离的影响,评估协流射流对雾滴的控制效果,提出协流射流细水雾灭火系统的设计方法。结果表明:对于小雾滴而言,增大喷头工作压力难以有效提高雾滴的穿透距离,雾滴易被逆气流夹带;协流射流能够减小雾滴速度衰减,提高雾滴穿透距离;协流作用下雾滴的运动特征有利于减小雾滴在烟气层中的汽化,增大进入火焰区的雾滴数量,从而提高雾滴的利用效率;按照协流射流细水雾灭火系统的设计方法可以初步确定该系统的结构参数和运行参数。

电子商务中企业物流模式的分析及选择

电子商务的快速发展暴露了我国物流系统的滞后 ,物流成为电子商务发展过程中亟待解决的问题。本文试对电子商务环境下的企业外部物流模式作分析 ,并就从事电子商务的企业如何选择合适的物流方式进行探讨。

供应链环境下企业物流模式的探讨

总结了物流在50年来的发展规律,从中国物流管理的现状出发,讨论了供应链环境下的几种可以选择物流管理模式．然后在此基础上,给出适合我国企业现状的物流管理策略。

激光诱导炽光法定量测量碳烟

利用激光诱导炽光法和高温双色法相结合,得出碳烟体积分数的量化结果;利用碳烟炽光信号衰减速率和炽光物理模型分析得出碳烟粒径的量化结果.分析讨论了LII模型对于不同压力范围内模型的适用性.搭建了LII测试系统,在一台协流部分预混燃烧器上开展了实验,燃料以正庚烷和甲苯作为基础,分别添加乙醇和正丁醇.实验结果显示,含氧燃料的添加有效降低了火焰中碳烟的生成量,同时验证了LII测试系统及定量测试方法的实用性.

活化热氛围下柴油喷雾燃烧特性试验

针对柴油燃料喷雾的自燃及燃烧特性,利用可控活化热氛围燃烧试验系统,结合连续喷射系统和高速摄影技术,研究协流温度对喷雾滞燃期、自燃点位置、火焰长度及宽度、火焰起升高度的影响.为活化热氛围下液体燃料自燃及燃烧模型的建立奠定了基础.

Carbon fluxes and their response to environmental variables in a Dahurian larch forest ecosystem in northeast China

The Dahurian larch forest in northeast China is important due to its vastness and location within a transitional zone from boreal to temperate and at the southern distribution edge of the vast Siberian larch forest. The continuous carbon fluxes were measured from May 2004 to April 2005 in the Dahurian larch forest in Northeast China using an eddy covariance method. The results showed that the ecosystem released carbon in the dormant season from mid-October 2004 to April 2005, while it assimilated CO2 from the atmosphere in the growing season from May to September 2004. The net carbon sequestration reached its peak of 112 g.m^-2.month ^-1 in June 2004 （simplified expression of g （carbon）.m^-2.month^-1） and then gradually decreased. Annually, the larch forest was a carbon sink that sequestered carbon of 146 g-m^-2.a^-1 （simplified expression of g （carbon）.m^-2.a^-1） during the measurements. The photosynthetic process of the larch forest ecosystem was largely affected by the vapor pressure deficit （VPD） and temperature. Under humid conditions （VPD 〈 1.0 kPa）, the gross ecosystem production （GEP） increased with increasing temperature. But the net ecosystem production （NEP） showed almost no change with increasing temperature because the increment of GEP was counterbalanced by that of the ecosystem respiration. Under a dry environment （VPD 〉 1.0 kPa）, the GEP decreased with the increasing VPD at a rate of 3.0 μmol.m^-2.s^-1kPa -1 and the ecosystem respiration was also enhanced simultaneously due to the increase of air temperature, which was linearly correlated with the VPD. As a result, the net ecosystem carbon sequestration rapidly decreased with the increasing VPD at a rate of 5.2 μmol.m^-2.s-1.kPa^-1. Under humid conditions （VPD 〈 1.0 kPa）, both the GEP and NEP were obviously restricted by the low air temperature but were insensitive to the high temperature because the observed high temperature value comes within the category of the optimum range.

AGENT-BASED WORKFLOW COORDINATION FOR SUPPLY CHAIN MANAGEMENT

To align customer demand with suppliers for reducing work in process and supply costs and increasing re sp onsiveness to customer requirements, a real time collaborative supply chain mana gement system is essential. A solution to the realization of supply chain manage ment capable of timely responding to customer requirements is proposed. Workflow automation is used to manage process interaction across enterprises; Agents can be automatically invoked by supply chain workflow process and are used to pro mote the flexibility and reconfigurability by providing the mechanism in support of distributed compution in an enterprises to meet the requirements of performa nce and business dynamics. An approach that supports agent based workflow proce ss in a supply chain is proposed. And the coordination mechanism between agents is also discussed.

Dynamic business process modeling and verification for inter-organizational collaboration

To achieve an on-demand and dynamic composition model of inter-organizational business processes, a new approach for business process modeling and verification is introduced by using the pi-calculus theory. A new business process model which is multi-role, multi-dimensional, integrated and dynamic is proposed relying on inter-organizational collaboration. Compatible with the traditional linear sequence model, the new model is an M x N multi-dimensional mesh, and provides horizontal and vertical formal descriptions for the collaboration business process model. Finally, the pi-calculus theory is utilized to verify the deadlocks, livelocks and synchronization of the example models. The result shows that the proposed approach is efficient and applicable in inter-organizational business process modeling.

Coordinated Development of Human Settlement and Economy in County-level Cities in the Yellow River Basin

[Objective] To provide quantification means for comprehensively analyzing the coordinated development of urban human settlement and economy by constructing an index system of economy and human settlement. [Method] By constructing an evaluation index system of economy and human settlement, and using the coordinate measurement model of them, 22 county-level cities in the Yellow River Basin were analyzed. [Result] In the Yellow River Basin, the construction level of economy and human settlement in those county-level cities is low with distinct spatial differences and deteriorating polarization; there is a great spatial corresponding between coordinated development degree and economic level, the higher the economic development level, the higher coordinated development degree in county-level cities; county-level cities around the boundaries of provinces have difficulties in development. [Conclusion] Evaluation standards and models are clear in significance, convenient in application, which can successfully evaluate the coordination of human settlement development in the study region.

TWO DIMENSIONAL SIMULATION OF SHORT-GATE-LENGTH GaAs MESFET's

【正】 The two dimensional steady stale numerical simulation system MESS for C-band power GaAs MESFET’s by finite clement method is presented in this paper. The improved charge lumping method and the hybrid finite clement and finite difference scheme are used in discritization of poisson-continuity system. The grid generation and the improved coupled method for the solution of the Semiconductor basic equation are discribcd.

Association of hepatitis C virus infection and diabetes

Epidemiologic studies have suggested a relation between hepatitis C virus (HCV) infection and diabetes mellitus. HCV infection is emerging as a metabolic disease, and diabetes mellitus as a risk factor for HCV infection. However, some data on the prevalence of antibodies to HCV in patients with diabetes are conflicting. These seroprevalence data should be interpreted with caution. Some potential bias may occur in those clinic-based studies that target a specif ic disease group. In this letter we explain some reasons for these conflicting studies.

CC-CV charge protocol based on spherical diffusion model

A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capacity loss in the CC process, and the capacity loss increases with increasing the charging rate and decreases with increasing the lithium-ion diffusion coefficient and using a smaller r value （smaller particle-size and larger diffusion coefficient） and a lower charge rate will be helpful to decreasing the capacity loss. The results show that the CC and the CV charging processes, in some way, are complementary and the capacity loss during the CC charging process due to the large electrochemical polarization can be effectively compensated from the CV charging process.

Field synergy analysis of different flow patterns in falling-film dehumidification system with horizontal pipes

Effects of the flow pattern of intertubular liquid film on mass and heat transfer synergies in a falling-film dehumidification system with horizontal pipes are studied.A flow model of the dehumidifying solution between horizontal pipes is established using Fluent software,the rule of transitions of the flow pattern between pipes is studied,critical Reynolds numbers of flow pattern transitions are obtained,and the accuracy of the model is verified by experiments.The mass transfer synergy angle and heat transfer synergy angle are respectively used as evaluation criteria for the mass transfer synergy and heat transfer synergy,and distribution laws of the synergy angles for droplet,droplet columnar and curtain flow patterns are obtained.Simulation results show that the mass transfer synergy angles corresponding to droplet,droplet columnar and curtain flow patterns all rise to a plateau with time.The mean mass-transfer synergy angle is 98°for the droplet flow pattern,higher than 96.5°for the droplet columnar flow pattern and 95°for the curtain flow pattern.The results show that the mass transfer synergy of the droplet flow pattern is better than that of the droplet columnar flow pattern and that of the curtain flow pattern.

Metro passenger flow control with station-to-station cooperation based on stop-skipping and boarding limiting

Metro passenger flow control problem is studied under given total inbound demand in this work,which considers passenger demand control and train capacity supply.Relevant connotations are analyzed and a mathematical model is developed.The decision variables are boarding limiting and stop-skipping strategies and the objective is the maximal passenger profit.And a passenger original station choice model based on utility theory is built to modify the inbound passenger distribution among stations.Algorithm of metro passenger flow control scheme is designed,where two key technologies of stopping-station choice and headway adjustment are given and boarding limiting and train stopping-station scheme are optimized.Finally,a real case of Beijing metro is taken for example to verify validity.The results show that in the three scenarios with different ratios of normal trains to stop-skipping trains,the total limited passenger volume is the smallest and the systematic profit is the largest in scenario 3.

Synergetic Analysis and Possible Control of Vortex-Induced Vibrations in a Fluid-Conveying Steel Catenary Riser

This work aimed to demonstrate possibilities for both active and passive control of the vortex-induced vibration and fatigue life of steel catenary risers via an analysis of the self-organization and evolution of the structural vibration based on synergetic theory. An analysis of the complex interrelated and synergistic relationship between the order parameter and the fast variable was performed, and the master equation of the nodal displacements was established as the order parameter for the evolution of the riser's structural vibration. Passive control methods include modifying the structure's elastic modulus, the internal fluid velocity, the top tension and the structural damping ratio, while an active control involves adjusting the external flow rate. Optimized parameters were obtained by analyzing the non-steady state solution of the master equation. The results show that the fatigue life greatly increases as the riser's elastic modulus decreases. In contrast, the fatigue life decreases with an increase of the internal fluid velocity. With an increase of the top tension, the vibration amplitudes and the number of modes may decrease, resulting in fewer bending stress cycles and a longer fatigue life. Furthermore, the structural damping ratio should be as large as possible. Finally, an active and passive control of the riser structure's response to vortex-induced vibration and its fatigue life can be achieved by carefully modifying the parameters mentioned above. The results may provide a theoretical framework for engineering practice concerning the design and control of steel catenary riser structures which are affected by vortex-induced vibration.