Digital monitoring for heavy duty mechanical equipment based on fiber Bragg grating sensor

The digital monitoring principle and technologies for heavy duty mechanical equipment based on fiber Bragg grating (FBG) technology are introduced in this paper. The fundamentals of new-style FBG sensing technology, including the photorefractive effect of FBG, the physical formation, and the relation between optical properties and grating parameters, are investigated. The plaster, encapsulation and distribution planning of FBG sensor (FBGS), which is used to monitor heavy duty mechanical equipment under abominable environment and extreme conditions, are also studied. In addition, theoretical and experimental researches on the strain, temperature, displacement, and stress transmission characteristics between FBGS and detection interface are presented. The principle and method for temperature compensation in non-uniformity temperature field are described in detail as well. Comparing with the traditional sensing monitoring techniques, the application of FBGS technology on digital monitoring and diagnosis for heavy duty mechanical equipment has a number of significant technical advantages and will make a new breakthrough in this field.     

Microstructure and texture evolution during warm compression of the magnesium alloy AZ31

The evolution of the microstructure and texture with strain during compression at 150℃ of the magnesium alloy AZ31 has been investigated using the electron backscattered diffraction (EBSD) technique. The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction. The EBSD data provide evidence concerning the relative activity of both {10-12} extension twinning and slip, and suggest that non-basal slip is important in samples deformed to a strain of more than 0.2. The relative contributions of the twinning and the slip during deformation have been discussed based on the results above.     

Renewal strategies for old industrial areas in the post-industrial age—Take “Zurich-West” in Switzerland as an example

This paper introduces and analyses the renewal planning of “Zurich-West”, an old industrial area. It points out that systematic and comprehensive target orientation, extensive collaboration in argumentation and decision-making, and the design ideas of coexistence and integration are the key to its success. Considering the status quo of China’s old industrial district remodeling, the paper offers some suggestions. Supported by the National Natural Science Foundation of China (Grant No. 50878045)     

Effect of coagulation temperature on structures and properties of poly(<Emphasis Type="Italic">p</Emphasis>-phenylene benzobisoxazole) (DHPBO) fibers during dry-jet wet-spinning process

The effect of coagulation temperature on the morphology, microstructures and mechanical properties of dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO) fibers was investigated during dry-jet wet-spinning process, in which the coagulation bath concentration and drawn ratio were kept as 10 wt% of PPA in water and 1.7, respectively. The structures and mechanical properties of the as-spun DHPBO fibers were characterized by FTIR, XRD, SEM, and single fiber tensile testing. The results indicated that in PPA/H₂O coagulation system, when the coagulation temperature was 25°C, highly crystallized DHPBO as-spun fibers possessing fine crystallites, circular and smooth morphology, and excellent mechanical properties could be achieved. Supported by the National Natural Science Foundation of China (Grant No. 50673017), Shanghai Leading Academic Discipline Project (Grant No. B603) and the Program of Introducing Taleuts of Discipline to University of People’s Republic of China (“111” Program) (Grant No. 111-2-04)     

Method of change management based on dynamic machining error propagation

In multistage machining processes(MMPs),the final quality of a part is influenced by a series of machining processes,which are complex correlations.So it is necessary to research the rule of machin-ing error propagation to ensure the machining quality.For this issue,a change management method of quality control nodes(i.e.,QC-nodes) for machining error propagation is proposed.A new framework of QC-nodes is proposed including association analysis of quality attributes,quality closed-loop control,error tracing...     

Introduction of fluorin into PBO polymer chains: Toward higher thermal stability and lower dielectric constant

A series of novel fluorinated benzoxazole polymers (6FPBO's) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihy-drochloride (DAR), 1,4-benzenedicarboxylic acid (PTA) and various amount of 4'4- (hexafluoroisopro-pylidene) bis (benzoic acid) (BIS-B-AF) in the medium of polyphosphoric acid (PPA). 6FPBO fibers were then obtained via dry-jet wet-spinning technique and characterized by means of Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), single fiber tensile testing machine and scanning electron microscopy (SEM). FTIR spectrum of 6FPBO fibers indicated that the fluorine groups had been incorporated into PBO molecular chains successfully. TGA curves revealed that 6FPBO fibers possessed high thermal stability just as pure PBO fibers. Moreover, dielectric constant spectrum of 6FPBO exhibited that the polymers had low dielectric constant, especially in the range of high- frequency.     

Discrimination for ablative control mechanism in solid-propellant rocket nozzle

The ablation in solid-propellant rocket nozzle is a coupling process resulted by chemistry, heat and mass transfer. Based on the heat and mass transfer theory, the aero-thermo-dynamic, and thermo-chemical kinetics, the thermal-chemical ablation model is established. Simulations are completed on the heat flow field and chemical ablation in the nozzle with different concentrations, frequency factors and activation energy of H2. The calculation results show that the concentration and the activation energy of H...     

一种多级跨域访问控制管理模型

访问控制管理为维护访问控制策略的安全、一致提供了重要保障。针对现有访问控制管理模型存在指派关系复杂、扩展性差、缺乏对跨域访问管理有效支撑的问题,结合多级跨域系统特性和访问控制管理的细粒度要求,文章提出了多级跨域访问控制管理模型,给出了模型的基本元素、元素关系、约束条件和管理规则。与现有研究相比,该模型具有良好的可扩展性,支持细粒度的管理操作,能够有效支撑多级跨域环境下安全、统一的访问控制管理。     

改善水泥性能满足施工需求的措施

1技术攻关方向保定太行和益水泥股份有限公司初期生产的水泥问题主要表现是和混凝土减水剂适应性比较差,需水量大,在施工过程中要多加水才能达到规定的水泥胶砂流动度,但多加水降低了混凝土制品的强度,相应使生产成本上升了。为解决这种情况,2004年以来     

正交法选择COPNA树脂的最佳合成条件

COPNA树脂可作为炭／炭复合材料的基体前驱体。为提高以苯甲醛为交联荆，蔡为单体，浓硫酸为催化剂的缩合多核芳香烃（COPNA）树脂的残炭率，采用正交实验，研究了合成COPNA树脂的交联荆与单体的摩尔比、催化荆的用量、反应温度等因素对树脂的残炭率的影响。结果表明：影响因子强度大小依次为交联剂与单体的摩尔比、催化荆用量、反应温度。通过正交实验得到的最佳反应条件是交联剂与单体的摩尔比为2．5、催化剂的用量为5％、反应温度170℃，此条件下合成的COPNA树脂的残炭率达到76％。