Mathematical Model of Flow Process in 40t/h Pyroflow Circulating Fluidized Bed Boiler

A mathematical model is presented to describe the fluiddynamics processes for the combustion system of 410t/h Pyroflow CFB boiler.A core annulus structure with solid dispersion from core to annulus is considered,and the influence of coal particles fragmentation,attrition and broad size distribution of feeding coal and bed inventory on hydrodynamics is specially taken into account.The simulation results show that the CFB boiler has good hydrodnamic characteristics and high hot cyclone efficiency.     

Dynamic Modeling and Simulation of 440 t/h Steam-cooled Cyclone Separator for CFB Boiler

A dynamic mathematical model of the steam-cooled cyclone separator in a 440 t/h CFB boiler has been established.Based on the mathematical model,simulation model of the cyclone separator is created with the advanced continuous simulation language(ACSL).The validity of this model has been verified by the simulation experiments and analysis.This model can provide a theoretical guidance for operation and optimal design of the cyclone separator.     

3-D Simulation on the Transient Heat Transfer Characteristics of Municipal Solid Waste Lump in Clean Incinerator

To be effectively heated in incinerator for MSW is very important for stabilization and completeness combustion, the smaller produce of the PCDD/Fs. At the same time, the transient heat transfer characteristics of the MSW lump decides the stay time of the MSW in incinerator and effects on the operation feature of the combustion equipments. All of these would lead to design the reasonable and clean combustion project, the optimum incinerator and recover energy system. The component, shape, dimension, property, the hardly and inner structure feature of the MSW lump are taken in account, and the effective conduct heat coefficient has been adopted. And then, the physical model is setup with different shape(ball, cylinder, squareness), and the 3-D mathematical model and conduct heat efficient with porous feature for transient heat transfer of MSW lump are presented, at the same time, the simulation tests are gotten in various boundary and the interesting conclusions are gotten: The center stable temperature of the MSW lump is mostly decided by the inner gas temperature of the incinerator and the heated area of the lump. The transient heat transfer characteristics is variously effected by the shape of the MSW lump in incinerator. The transient process becomes longer and the center stable temperature decreases, the volatile can't be easily separated out and the combustion efficiency decreases because of the increasing of the lump feature dimension.     

Simulation on human-machine cooperation strategy in production cells

To adapt to the rapid changes of manufacturing environment,production cell needs to focus on high qualified staff and flexible human-machine cooperation method at the same time,when advanced manufacturing technology(AMT) is emphasized on. In order to study human-machine cooperation strategy dynamically and quantitatively in production cells,a simulation study which combined computer simulation with agent modeling technology is carried out. Firstly,a human-computer cooperation simulation model is established,and its realization method is presented. Secondly,specific cooperation mechanisms of designated production cell cooperation,partly independent cooperation and completely independent cooperation are studied respectively. Finally,an engine production cell is taken as an example,a series of simulation experiments are designed,and four performance indicators of the task waiting time,order on time percentage,waiting rate of machine and operator utilization are established to analyze and evaluate all kinds of man-machine division modes of the production cell to find a more reasonable mode.     

Study on Heat and Mass Transport of Porous Saline Materials

On_site measurement and numerical modeling are made for the interior heat mass distribution. The heat and mass coupling equation system to the porous saline materials in one-dimensional temperature and mass degree field was established. The dynamic distribution features of the materials in moderate temperature and mass degree field were obtained. The result of numerical modeling coincided with that of actual measurement and testified to the numerical model. The study has significance in promoting the interrelated sciences in their studies on the problem of heat and mass transport in porous saline materials.     

One Dimensional Steady Model for Natural Ventilation of Solar Chimney

Solar chimney is effective to enhance the natural ventilation by heating the air with solar radiation. Based on the research by other authors, a revised mathematical model is proposed. One dimensional heat conduction model is proposed when the thermal resistance of both the glass cover and heat absorbing wall are taken into account. The mean temperatures of the air and heat absorbing wall, the air mass rate and heat collection efficiency in the solar chimney are calculated with the present model. The results of the present model are compared with the related experimental data and reasonable agreement is validated. It is shown that the present revised model is able to predict the temperatures of the air and wall, the air mass rate and heat collection efficiency more preciously than the original model.     

Coupled Thermo-Elastic Contact Finite Element Method and It''s Application in Gearing

A new finite element method is presented in this paper to analyze the thermo- elastic contact problem with heat input on meshing tooth faces. The computational model of meshing gear has been established and the frictional heat input on meshing tooth faces is estimated. In addition, 2-D finite element analysis program for this kind of problem is listed. The test and practical examples are given to show the validity and versatility of this method.     

Influence of oygen-enriched combustion technology on overall performance of 220 t/h gas boiler

A 220 t/h gas boiler of some steel group is taken as the study objectand the idea of oxygen-enriched stable combustion is proposed and proved to be feasible with the furnace heat transfer model in order to make reasonable use of existing resources and improve the combustion stability of gas boiler in low load operation.Detailed analysis has been made about the effects of oxygen-enriched combustion on the flu gas temperaturecombustion stability boiler thermal efficiency and so on.The results show that the oxygen-enriched combustion technology can greatly improve the overall performance of the boiler.     

Study on Evaluating the Pozzolanicity of CFB Sulphur- Fixed Coal Ashes

There is no appropriate method or uniform standard for evaluating the pozzolanicity of CFB sulphur-fixed coal ashes,leading to difficulty in use of it as building material,because CFB sulphur-fixed coal ash has higher content of f-CaO and SO_3 than that of ordinary ash.In this paper the appropriate evaluating methods are developed through theoretical analysis and experiments with reference to the National standards GB2847 for the pozzolanic materials and GB12957-91for the testing method of the activity of the industrial wastes,the compressive strength ratio is suggested by determination of 28 day compressive strength ratio of ground CFB sulphur-fixed coal ashes-clinker to ground clinker.It is shown that this evaluating method gives the results consistent with those from other methods.     

Thermal Radiation Effects on Smoke-flow in Atrium Fires

The field models for smoke flow in atrium, takings into account strong buoyancy, turbulence, radiation exchange and wall heat losses are developed according to the characteristics of the atrium fire. Realistic combustion processes in the burning fuel have not been included. A six-flux radiation model is included in a general mathematical model for fires, which are taking as a volumetric heat source, It is applied to the predictions of fire smoke development in a small-scale atrium. In order to avoid complicated radiation exchange models, radiation heat loss effects are combined to the wall heat loss. A General-purpose compute program PHOENICS has been developed to meet this need. Results of numerical calculations based on the field model are compared with test data for a fire in the small-scale atrium test facility. The resullts indicate that radiation transfer has the minor effects, due to the relatively low temperatures encountered. The method that the effect of radiation is included in the calculation of wall heat transfer losses by using maximum heat transfer coefficient is feasible. The field model used in the present study is not good enough, which a turbulent combustion sub-model must be included.     

Advance in Mathematic Model of Solidification Heat Transfer Process in Continuous Casting

The mathematic model of solidification heat transfer process in continuous casting strand is useful for quantitatively analyzing heat transfer in continuous casting process, quality control and process control. The heat transfer in continuous cast strand in crystallizer and secondary cooling zone have been analyzed. The attention has been paid to basic logic and methodology in model building up. Typical methods determing solution condition and parameters for the model have been discussed. Some numerical methods at the present time for solving solidification heat transfer model, such as finite difference method, finite-element method and boundary element, have been investigated comparatively. In the future, working on solidification heat transfer model, which is more practical, and the integration of the control model will play an important role in the development of high efficiency continuous casting technology.     

Product Lifecycle Information Model

The technology of product modeling is the basis of Advanced Manufacturing Technologies.Product model is the key to realize sharing information in developing product.Three kinds of product model are compared.Base on it,the concept of product lifecyele information model and its components,the architecture and the approach to modeling are presented.     

Numerical Study on the Thermal-Mechanical Stability ofQinghai-Tibet Railway Embankment in Permafrost Regions

According to some basic theories of physics of frozen soil, heat transfer, frozen soil mechanics and frozen soil rheology, a mathematical model for moisture, heat and stress analysis of frozen embankment is established, in which the moisture and heat field are interacted with each other, the mechanical properties of frozen soil is decided by soil temperature and a in-situ test creep equation of frozen soil is also introduced. Meanwhile, its finite element program is written. Then, an experimental section of Qinghai-Tibet is taken as example, and the thermal-mechanical stability of the embankment is studied in detail. Through comparing with observational data, it is found that, the proposed analytical model is correct and reasonable, and it can well describe and predict the long-term stability of the embankment of Qinghai-Tibet railway.     

基于层次分析法的工矿废弃土地复垦潜力分区研究

工矿废弃土地复垦潜力分区评价的合理程度,对复垦工作的实施与管理有着密切的联系。为了对工矿废弃土地复垦潜力分区作出科学客观的评价,采用层次分析法建立了描述和评价复垦潜力分区的数学模型,该模型能综合考虑到复垦潜力各层次各因素对最后评价结果的影响,能同时定性和定量地对复垦潜力分区进行分析。实际使用情况表明,该模型有着很好的工程应用前景。     

THE VISCOELASTOPLASTIC BOUNDARY ELEMENT ANALYSIS FOR THE UNDERGROUND ROCK CAVERNS

In this paper,the theological model is presented,and the ba-sic principle of the viscoelastoplastic problem is worked out by the boundaryelement direct method,and the relevent formulations are derived.Several exam-ples show that the theological model and the corresponding boundary elementmethod presented in this paper are effective and reasonable.     

Dynamic Modeling and Analysis for a Humanoid Robot

To resolve the kinematics modeling and dynamics modeling of a humanoid robot with complicated machine, a modeling method based on the conventional mechanism combined with neural network is presented. First the kinematics formulas are deduced by analyzing its geometry structure. Second, the dynamics models are built up with Lagrange-Euler method combined with the define of interactive force among all parts of the humanoid robot. The interactive force is realized by neural network method. Finally, the true robot parameters are applied to the model. The simulation results show the validity of the modeling. So, the method is practical and available.     

Control model for secondary cooling of continuous casting based on compensation temperature of the difference between liquidus and solidus

During continuous casting process, the composition of molten steel often varies with different heats, which leads to the big fluctuation of billet surface temperature when the traditional parameter water control model is applied to control the process. Additionally, it is difficult to keep the temperature at the straightening point of the billet within a reasonable range. Given above consideration, a new control model for secondary cooling of continuous casting based on compensation temperature of the difference between liquidus and solidus has been presented. Meanwhile, the temperature field of the billet is simulated with both the parameter water control model and the new secondary cooling control model, and the results indicate that the new control model for secondary cooling of continuous casting could perform better when it is used to control the surface temperature at straightening points of billet, thereby ensuring the quality of the billet.     

口蹄疫OA／58病毒株VP2蛋白结构模拟与B细胞抗原表位的分析

以口蹄疫病毒株OA/58 RNA为模板,反转录并扩增目的cDNA,然后与pMD18-T载体连接并转化JM109菌株,提取的重组质粒用凝胶电泳、PCR和BamH I,Hind III双酶切法鉴定。运用同源模建得到OA/58 VP2蛋白三维空间结构,并结合理化性质、亲水性、可塑性和免疫原性进行分析,找出OA/58 VP2蛋白的B细胞抗原表位。结果表明,OA/58 VP2蛋白存在多个潜在的抗原表位,可能的蛋白质抗原表位区域:1~23,40~63,71~78,82~91,102~106,113~119,131~138,148~154,166~177,189~196,212~218。应用同源模建得到的OA/58 VP2蛋白三维空间结构来预测其B细胞表位,为进一步研究OA/58 VP2蛋白在引起易感宿主体液免疫应答方面提供了一种可视化的技术平台,并且为选择表达其他口蹄疫病毒株的VP2蛋白分子提供有参考价值的信息。     

Identifying the impact of multi-hazards on crop yield—A case for heat stress and dry stress on winter wheat yield in northern China

Winter wheat production in northern China severely suffered from high temperatures and low relative humidity. However, the spatio-temporal pattern of heat stress and dry stress and the impacts of these multi-hazards on winter wheat yield have rarely been investigated. Using historical climate data, phenology data and yield records from 1980 to 2008, an analysis was performed to characterize the spatio-temporal variability of heat stress and dry stress in the post-heading stages of wheat growth in northern China. Additionally, these stresses’ impacts on winter wheat yield fluctuations were evaluated. Spatially, the central and northern parts of northern China have seen more serious heat stress, while greater dry stress has been observed in the northwest and north of the research area. Temporally, the heat stress has increased in the western part but decreased in the central and eastern parts of research area. Dry stress has aggravated in the entire northern China during the past decades, indicating the complexity of the exposure to adverse climate conditions. These two hazards (heat stress and dry stress) have contributed significant yield loss (up to 1.28% yield yr⁻¹) in most parts of the research region. The yield in the west was more sensitive to heat stress, and dry stress was the main hazard in the south. Additionally, the opposite spatial pattern between the sensitivity and exposure revealed that the climate is not the only factor controlling the yield fluctuation, the local adaptation measures used to mitigate negative influences of extreme events should not be ignored. In general, this study highlighted a focus on the impacts of multi-hazards on agricultural production, and an equal importance of considering local adaptation ability during the evaluation of agricultural risk in the future. Additionally, paying more attention to higher sensitive areas and to more reasonable and practical adaptive strategies is critical and significant for food supply security.     

地源热泵技术在中国温室设施中的应用探讨

当前在中国温室设施中应用和推广地源热泵技术尚存在诸多不利因素,大大限制了该项技术在设施农业领域中的发展。为探寻合理的解决途径,对地源热泵空调系统的关键技术和其在中国的发展概况进行了相关的阐述和分析,并以中国农业大学上庄实验站已经建成使用的地下水式温室地源热泵空调系统为实例,介绍该系统的组成、工作流程、性能参数和使用情况,探讨温室地源热泵空调系统在推广和使用中可能出现的投资较高,长时间运行性能不稳定等问题,分析其原因并提出相应的对策建议。