双相不锈钢在管流系统中的流动腐蚀动力学模型

针对管流体系 ,根据动量、能量和质量守恒原理 ,应用壁函数、k -ε湍流运动模型确立了管流体系中的计算流体力学模型和质量传递模型 ;结合腐蚀实验确定双相不锈钢流动腐蚀过程中的主要控制因素及其影响程度 ,分析了动力学过程 ,建立了双相不锈钢在 3.5 %NaCl溶液中的流动腐蚀动力学模型 .同时 ,采用数值计算方法计算了流动腐蚀速度 ,并与实验结果进行了验证 .揭示出双相不锈钢的流动腐蚀受阳极钝化过程控制 ,离子在电极表面钝化膜中的迁移、扩散过程为速度控制步骤 .

强迫对流管道内壁结垢层几何形状的逆运算估计

利用逆运算法中的共轭梯度法与差异原理,通过测量管壁内的温度,来估算一管流系统内壁结垢层厚度的几何形状.过程中未预先设定结垢层厚度的函数形式.因此,可将这类逆运算问题归类为"函数预测".逆运算过程的管壁温度测量值,可由直接解法所求得的温度数值来仿真实际的测量温度.并用测量误差来检验逆运算分析的正确性.数值实验结果显示,管内壁结垢层厚度的几何形状可获得极佳的估算值.所提出的技术可用作管路维修的预警系统,当管壁结垢层厚度超出某预先设定值时可适时发出维修警示.

基于细管流紫外反应系统探讨紫外和真空紫外/紫外辐照下水中微量磺胺甲噻二唑的光降解效果

水环境中存在的微量有机污染物可在较低浓度下对人类造成较大的危害.基于细管流紫外反应系统(MFPS)研究了典型微量有机污染物磺胺甲噻二唑(SML)在紫外(UV)和真空紫外/紫外(VUV/UV)辐照下的光降解过程,发现SML在VUV/UV辐照下的降解速率明显快于UV辐照.采用MFPS测定了各光化学动力学参数:UV和VUV/UV辐照下光子剂量基反应速率常数分别为0.88×10~3和4.64×10~3m^2·einstein-1;量子产率分别为0.227和0.379;羟基自由基(HO·)和SML的二级反应速率常数测定为6.59×10~9L·mol^(-1)·s^(-1).探讨了pH值和初始SML浓度对降解效果的影响,结果表明,VUV/UV辐照下pH 7.0时的SML降解速率达到最大,而UV辐照下SML的降解速率随pH增加而逐渐增大;初始SML浓度的增大会降低UV和VUV/UV辐照下的降解速率.此外,本研究表明MFPS作为实验室光反应系统可快速、准确地测量各光反应动力学参数,VUV/UV在去除水中微量有机污染物方面的效果优于UV,可较好的处理水中微量有机污染物.

Characteristics of turbulent flow distribution in branch piping system

Flow distribution in branch piping system is affected by flow characteristics and different geometric variations. Most of the flow distribution studies are performed with one-dimensional analysis to yield overall information only. However, detailed analysis is required to find effects of design parameters on the flow distribution. For this aspect, three-dimensional turbulent flow analysis was performed to assess turbulence model performance and effects of upstream pressure and branch pipe geometry. Three different turbulence models of standard k-e model, realizable k-e model and standard k-co yield similar results, indicating small effects of turbulence models on flow characteristics analysis. Geometric variations include area ratio of main and branch pipes, branch pipe diameter, and connection shape of main and branch pipes. Among these parameters, area ratio and branch diameter and shape show strong effect on flow distribution due to high friction and minor loss. Uniform flow distribution is one of common requirements in the branch piping system and this can be achieved with rather high total loss design.

Second-Order Consensus of Multiple Agents with Coupling Delay

In this paper, we investigate two kinds of second-order consensus algorithms for multiple agents with coupling delay under general fixed directed information topology. Stability analysis is performed based on Lyapunov- Krasovskii functional method. Delay-dependent asymptotical stability condition in terms of linear matrix inequalities （LMIs） is derived for the second-order consensus algorithm of delayed dynamical networks. Both delay-independent and delay-dependent asymptotical stability conditions in terms of LMIs are derived for the second-order consensus algorithm with information feedback.

On the mechanical behavior of the human biliary system

This paper reviews the progress made in understanding the mechanical behaviour of the biliary system. Gallstones and diseases of the biliary tract affect more than 10% of the adult population. The complications of gallstones, i.e. acute pancreatitis and obstructive jandice, can be lethal, and patients with acalculous gallbladder pain often pose diagnostic difficulties and undergo repeated ultrasound scans and oral cholecystograms. Moreover, surgery to remove the gallbladder in these patients, in an attempt to relieve the symptoms, gives variable results. Extensive research has been carried out to understand the physiological and pathological functions of the biliary system, but the mechanism of the pathogenesis of gallstones and pain production still remain poorly understood. It is believed that the mechanical factors play an essential role in the mechanisms of the gallstone formation and biliary diseases. However, despite the extensive literature in clinical studies, only limited work has been carried out to study the biliary system from the mechanical point of view. In this paper, we discuss the state of art knowledge of the fluid dynamics of bile flow in the biliary tract, the solid mechanics of the gallbladder and bile ducts, recent mathematical and numerical modelling of the system, and finally the future challenges in the area.

The dynamic power management for embedded system with Poisson process

The mass of the embedded systems are driven by second batteries, not by wired power supply. So saving energy is one of the main design goals for embedded system. In this paper we present a new technique for modelling and solving the dynamic power management (DPM) problem for embedded systems with complex behavioural characteristics. First we model a power-managed embedded computing system as a controllable Flow Chart. Then we use the Poisson process for optimisation, and give the power management algorithm by the help of Dynamic Voltage Scaling (DVS) technology. At last we built the experi- mental model using the PXA 255 Processors. The experimental results showed that the proposed technique can achieve more than 12% power saving compared to other existing DPM techniques.

Lightweight SOA-Based Twin-Engine Architecture for Enterprise Systems in Fixed and Mobile Environments

Mobile devices as a popular computing platform for enterprise systems have enabled certain tasks to be executed out of office.However,the work may be interrupted due to the server shutdown or network disconnection when employees access traditional single-engine Business Process Management System.To overcome this defect,we present a lightweight twin-engine architecture based on Service Oriented Architecture(SOA).In this paper,we discuss in detail the design and implementation of the architecture,and present a trigger mechanism to activate engines according to the states of hybrid environments since it is critical for the two types of engines to cooperate closely in hybrid environments with fixed and mobile computing resources.The experimental results validate the usability of the architecture.

Environmental Protection of Biodiversity in Macedonia and Albania under Legal Analysis View

Environmental problems in the Republic of Macedonia and Albania are similar in other countries in the region. Numerous problems and deficiencies identified through different projects. The studies and planning documents are evident for environmental media and areas. Such as lack of regional integrated systems for municipal solid waste management. The system for special waste types management, including hazardous waste, insufficient coverage of populated places and municipalities by wastewater collection and treatment systems （especially in agglomerations above 10,000 populations）. The need to establish integrated river basin management is in accordance with the new law on waters, air pollution with different intensity in different parts of the country. This paper presents the imperative reforms to protect the natural resources and biodiversity in the countries.

Modeling and Analysis of Data Dependencies in Business Process for Data-Intensive Services

With the growing popularity of data-intensive services on the Internet, the traditional process-centric model for business process meets challenges due to the lack of abilities to describe data semantics and dependencies, resulting in the inflexibility of the design and implement for the processes. This paper proposes a novel data-aware business process model which is able to describe both explicit control flow and implicit data flow. Data model with dependencies which are formulated by Linear-time Temporal Logic(LTL) is presented, and their satisfiability is validated by an automaton-based model checking algorithm. Data dependencies are fully considered in modeling phase, which helps to improve the efficiency and reliability of programming during developing phase. Finally, a prototype system based on j BPM for data-aware workflow is designed using such model, and has been deployed to Beijing Kingfore heating management system to validate the flexibility, efficacy and convenience of our approach for massive coding and large-scale system management in reality.

Flow Pattern and Pressure Fluctuation of Severe Slugging in Pipeline-riser System

During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.

Development of a distribution management system in refinery industry

Developing an information system for managing the product distribution in a refinery demands sophisticated design solutions. First, organization models are created to describe the structural relationships among employees and the ways in which they will use the information system. Second, function models are created to hierarchically describe how sales, transports, deliveries and vehicles are managed. Thirdly, an information model is built to represent the data entities and their dynamic interactions. Based on the system design, a distribution management system is developed and implemented in a refinery, which has considerably increased the distribution management efficiency and effectiveness.

A Hybrid Authorization Model For Project-Oriented Workflow

In the context of workflow systems, security-relevant aspect is related to the assignment of activities to (human or automated) agents. This paper intends to cast light on the management of project-oriented workflow. A comprehensive authorization model is proposed from the perspective of project management. In this model, the concept of activity decomposition and team is introduced, which improves the security of conventional role-based access control. Furthermore, policy is provided to define the static and dynamic constraints such as Separation of Duty (SoD). Validity of constraints is proposed to provide a fine-grained assignment, which improves the performance of policy management. The model is applicable not only to project-oriented workflow applications but also to other teamwork environments such as virtual enterprise.

A prototype of workflow management system for construction design projects

A great deal of benefits can be achieved if information and process are integrated within the building design project. This paper aims to establish a prototype of workflow management system for construction design project through the application of workflow technology. The composition and function of prototype is presented to satisfy the needs of information share and process integration. By integrating all subsystems and modules of the prototype, the whole system can deal with design information-flow modeling, emulating and optimizing, task planning and distributing, automatic tracking and monitoring, as well as network service, etc. In this way, the collaborative design environment of building design proiect is brought into being.

Continuous query scheduler based on operators clustering

Data stream management system (DSMS) provides convenient solutions to the problem of processing continuous queries on data streams.Previous approaches for scheduling these queries and their operators assume that each operator runs in separate thread or all operators combine in one query plan and run in a single thread.Both approaches suffer from severe drawbacks concerning the thread overhead and the stalls due to expensive operators.To overcome these drawbacks,a novel approach called clustered operators scheduling (COS) is proposed that adaptively clusters operators of the query plan into a number of groups based on their selectivity and computing cost using S-mean clustering.Experimental evaluation is provided to demonstrate the potential benefits of COS scheduling over the other scheduling strategies.COS can provide adaptive,flexible,reliable,scalable and robust design for continuous query processor.

The current status, threats and protection way of Sanjiang Plain wetland, Northeast China

The Sanjiang Plain is a vast area of alluvial floodplains and low hills in northeast Heilongjiang Province. It is the largest tract of wetlands in China and East Asia outside of Siberia. 28 wetland nature reserves exist on the Sanjiang Plain, and three of them have been listed as wetlands of international importance to water bird conservation by the Ramsar Convention Bureau. The wetlands of Sanjiang Plain are noteworthy for its rich biodiversity, but they continue to decline in area and deteriorate in quality currently. The main threats or constrains, immediate cause, root cause and required response are analyzed in this paper, and the four aspects opinion such as improvement of watershed management, enhancement of protection and restoration of habitats and biodiversity, alternative livelihoods of rural residents living in and near natural wetland reserve, and reinforcement of capacity building of natural reserves are brought forward as the effective measures for the Sanjiang Plain wetland protection.

Thyristor Controlled Phase Shifter:A Comprehensive Survey

Thyristor control phase shifter (TCPS) is one of the new facilities implemented in power network, leading to the development of economically efficient and technically reliable system. This paper introduces the function of TCPS in power system, describes its working principle and structure, and suggests some simple models used in its study and briefly presents the comparison between different types of TCPSs and their applications.

Asymmetric breakup of a droplet in an axisymmetric extensional flow

The asymmetric breakups of a droplet in an axisymmetric cross-like microfluidic device are investigated by using a three-dimensional volume of fluid(VOF) multiphase numerical model. Two kinds of asymmetries(droplet location deviation from the symmetric geometry center and different flow rates at two symmetric outlets) generate asymmetric flow fields near the droplet, which results in the asymmetric breakup of the latter. Four typical breakup regimes(no breakup, one-side breakup, retraction breakup and direct breakup) have been observed.Two regime maps are plotted to describe the transition from one regime to another for the two types of different asymmetries, respectively. A power law model, which is based on the three critical factors(the capillary number,the asymmetry of flow fields and the initial volume ratio), is employed to predict the volume ratio of the two unequal daughter droplets generated in the direct breakup. The influences of capillary numbers and the asymmetries have been studied systematically in this paper. The larger the asymmetry is, the bigger the oneside breakup zone is. The larger the capillary number is, the more possible the breakup is in the direct breakup zone. When the radius of the initial droplet is 20 μm, the critical capillary numbers are 0.122, 0.128, 0.145,0.165, 0.192 and 0.226 for flow asymmetry factor AS= 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5, respectively, in the flow system whose asymmetry is generated by location deviations. In the flow system whose asymmetry is generated by two different flow rates at two outlets, the critical capillary numbers are 0.121, 0.133, 0.145, 0.156 and 0.167 for AS= 1/21, 3/23, 1/5, 7/27 and 9/29, respectively.

Design and Implementation of Agricultural Products Logistics Management System based on WebGIS

The system will be to build a complete logistics monitoring system based on WebGIS, using the development technology of the third party map which is popular at present, the client technology Ajax is introduced into the two map development platform based on WebGIS, draw lessons from the mature MapABC map service interface for API programming, establish the optimization model of distribution route with hard time windows, and studies the application of tabu search algorithm to solve the distribution path optimization model. At the same time, t;he system can realize vehicle abnormal alarm, shortest path planning and analysis of statistical query functions, can display the corresponding curves on the map that query be some statistical analysis results or a heat map by the user, get a more intuitive feel and better user experience.

Scarcity within Opulence:Water Management in the Karakoram Mountains Revisited

Water management in general and in the Indus Basin in particular is concerned with the energy-efficient transportation of hydrologically exploitable resources from the upper zone to climatically favourable areas where irrigation helps to supersede arid conditions for the cultivation of crops and watering of meadows.In other words:Human intervention sets the stage for the allocation of water from a wider catchment area in a smaller habitat where this resource is deficient.Emphasis on mountain irrigation practices is counteracted with developments in the forelands where different frame conditions prevail and peculiar development problems occur.In dealing with the importance of water from the mountain regions three dimensions have to be evaluated:1) natural factors and their validity for the environmental frame conditions and technological adaptation processes;2) social factors and their impact on culture,economy and equitability;3) institutional factors and their importance for sustainable growth and for the implementation of development projects.In the study of decentralized irrigation systems in high mountain regions of the Indus Basin a systems theoretical approach values the complexity of interrelationships between different systems elements.Human activities in arid mountain regions are restricted by limiting ecological factors and are characterized by certain utilization and adaptive strategies.