浅析电厂锅炉运行效率的影响因素及对策

在电厂运行中,锅炉是最重要的设备之一,它与整个电厂的安全、稳定运行有着密切的关系,因此,提高电厂锅炉的运行效率是保证电厂长远发展的有效途径。分析了影响电厂锅炉运行效率的因素,提出了提高电厂锅炉运行效率的对策,以期能够促进电厂经济效益的不断提高。     

Influence of untreated and novel electron‐beam‐modified surface‐coated silica filler on the thermorheological properties of ethylene–octene copolymer

We developed surface‐modified silica fillers by coating these with an acrylate monomer, trimethylolpropane triacrylate, or a silane coupling agent, triethoxyvinyl silane, followed by electron‐beam irradiation at room temperature. These were incorporated in an ethylene–octene copolymer rubber. Thermorheological studies of the unvulcanized ethylene–octene copolymer and its untreated and modified silica‐filled composites were done with a shear dynamic oscillating rheometer. Modification of the silica filler, especially via the silanization process followed by electron beam treatment, significantly reduced filler–filler networking as revealed from the log–log plots of storage modulus and complex shear viscosity, and its real component. The rheological complexity of the compositions was analyzed from a double logarithmic plot of the storage modulus and loss modulus. The results obtained from the master curves constructed on the basis of the time–temperature superposition principle and the activation energy calculated from the Arrhenius equation for the flow of above these compounds further supported these findings. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2453–2459, 2003     

大型常压锥顶贮罐的设计

以工程实例为依据，论述国内以往较少采用的大型梁柱式支承锥顶贮罐的结构，介绍了国内外相关设计标准，给出了贮罐的典型结构－斜椽，横梁和立柱的计算公式，并用Excel电子表格编制了计算书。     

Molecular motions of non-crystalline poly(aryl ether-ether-ketone) PEEK and influence of elecron beam irradiation

The dynamic mechanical relaxation of non-crystalline poly(aryl ether-ether-ketone) PEEK and the one irradiated with electron beam were studied. The three distinct γ, β, α′ relaxation maxima were observed in unirradiated PEEK from low to high temperature. It was revealed from the study on the irradiation effects that three different molecular processes are overlapped in γ relaxation peak, i.e., molecular motion of water bound to main chain (peak temperature; at ?100°C), local motion of main chain (at ?80°C), and local mode of the aligned and/or oriented moiety (at ?40°C). The β relaxation connected with the glass transition occurred at 150°C and it shifted to higher temperature by irradiation. The α′ relaxation which can be attributed to rearrangement of molecular chain due to crystallization was observed in unirradiated PEEK ～ 180°C and its magnitude decreased with the increase in irradiation dose. This effect indicates the formation of structures inhibiting crystallization such as crosslinking and/or short branching during irradiation. A new relaxation, β′, appeared in the temperature range of 40° to 100°C by irradiation and its magnitude increased with dose. This relaxation was attributed to rearrangement of molecular chain from loosened packing around chain ends, which were introduced into the non-crystalline region by chain scission under irradiation, to more rigid molecular packing, From these observations, we proposed that deterioration in mechanical properties of non-crystalline PEEK by high energy electron beam was brought about not only by chain scission but structural changes such as crosslinking and/or branching in the main chain.     

Application of open-pit and underground mining technology for residual coal of end slopes

Given the conditions of residual coal from the boundary of a flat dipping open-pit mine,which uses strip areas mining and inner dumping with slope-covering,we propose an open-pit and underground integrated mining technology for residual coal of end slopes.In the proposal a conveyance road and ventilation conveyance near the slope are built,corresponding to the pit mining area and the surface coal mine dump,as well as an interval haulage tunnel and air-inlet tunnel.The outcome shows that such mining method may reduce the effect to slope stability from underground mining,it does not affect the dumping advance and has a high recovery rate of residual coal resources.The working face is timbered by single hydraulic props,transported by a scraper conveyor and supported by coal walls.This method of mining is one of layered top coal caving,with high resource recovery,low production cost where positive economic benefit can be realized.     

双洞口配筋砌块砌体框支墙梁试验

为研究双洞口配筋砌块砌体框支墙梁地震前后的受力模式,在拟动力子试验前后进行了底层框架配筋砌块短肢砌体剪力墙结构三层足尺模型的竖向力静载试验.试验结果表明:托梁与上部墙体表现出良好的协同工作能力,其工作模式为拉杆拱.通过对其在拟动力试验前后的受力模式进行了比较,可知带洞口配筋砌块砌体框支墙梁结构体系在墙体受到一定损伤时,并不会使墙梁的受力机理发生明显改变.     

CFRP加固钢筋混凝土梁滞后应变计算方法

为了系统研究从零负载状态到满负载状态各个阶段CFRP片材加固梁滞后应变的计算方法,在充分考虑加固梁不同负载状态及受压区混凝土非线性本构关系的基础上,分别建立了不同负载贴片加固梁考虑混凝土抗拉作用时的滞后应变计算公式及不考虑混凝土抗拉作用时的简化计算公式.试验数据和对比分析结果表明:"考虑混凝土抗拉作用"公式的计算结果与试验数据吻合良好,计算误差<8%,明显优于现有文献的计算方法;"不考虑受拉区混凝土抗拉作用"公式的计算结果在混凝土开裂前和试验值相差较大,但对已裂加固梁的计算误差与"考虑混凝土抗拉作用"公式的计算误差接近.为简化计算,对未裂和已裂混凝土梁贴片加固时的滞后应变可分别采用"换算截面"公式和"不考虑混凝土抗拉作用"公式进行计算,两种简化方法的误差均不会超过10%.     

简支梁多位置损伤识别研究

曲率模态是结构损伤识别的敏感标示量,采用数值仿真方法,把曲率模态用于桥梁损伤识别.利用简支梁损伤前后一阶曲率变化率作为识别参数,便可明显确定其多处损伤位置.对相关样本参数进行归一化处理并引入噪声干扰,利用BP人工神经网络进行数值仿真计算,也能对其损伤程度进行有效模拟,验证了BP神经网络也有很强的泛化能力及容错能力.     

Zipf定律在划定经济区域内的实证研究——以长江三角洲经济区为例

国外关于Zipf定律的实证研究的区域空间多采用国家层次,而国内关于Zipf定律的实证研究则涉及国家、跨省的经济区及行政省的不同层次,于是这就有可能存在经济区域空间划定是否合理的问题。现以长江三角洲地区为例,通过修正的引力模型计算城市之间的经济联系强度及潜能,以此进行长江三角洲经济区域的空间划定,并在划定的经济区域内进行Zipf定律的实证研究,以验证经济区域空间划定是否合理。研究结果显示了经济区域空间划定的合理性。     

Towards evolvable Internet architecture-design constraints and models analysis

There is a general consensus about the success of Internet architecture in academia and industry. However, with the development of diversified application, the existing Internet architecture is facing more and more challenges in scalability, security, mobility and performance. A novel evolvable Internet architecture framework is proposed in this paper to meet the continuous changing application requirements. The basic idea of evolvability is relaxing the constraints that limit the development of the architecture while adhering to the core design principles of the Internet. Three important design constraints used to ensure the construction of the evolvable architecture, including the evolvability constraint, the economic adaptability constraint and the manageability constraint, are comprehensively described. We consider that the evolvable architecture can be developed from the network layer under these design constraints. What＇s more, we believe that the address system is the foundation of the Internet. Therefore, we propose a general address platform which provides a more open and efficient network environment for the research and development of the evolvable architecture.