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1.
Structural health monitoring system based on multi-agent coordination and fusion for large structure
In practical applications of structural health monitoring technology, a large number of distributed sensors are usually adopted to monitor the big dimension structures and different kinds of damage. The monitored structures are usually divided into different sub-structures and monitored by different sensor sets. Under this situation, how to manage the distributed sensor set and fuse different methods to obtain a fast and accurate evaluation result is an important problem to be addressed deeply. In the paper, a multi-agent fusion and coordination system is presented to deal with the damage identification for the strain distribution and joint failure in the large structure. Firstly, the monitoring system is adopted to distributedly monitor two kinds of damages, and it self-judges whether the static load happens in the monitored sub-region, and focuses on the static load on the sub-region boundary to obtain the sensor network information with blackboard model. Then, the improved contract net protocol is used to dynamically distribute the damage evaluation module for monitoring two kinds of damage uninterruptedly. Lastly, a reliable assessment for the whole structure is given by combing various heterogeneous classifiers strengths with voting-based fusion. The proposed multi-agent system is illustrated through a large aerospace aluminum plate structure experiment. The result shows that the method can significantly improve the monitoring performance for the large-scale structure. 相似文献
2.
3.
The water–LiBr absorption machine was analyzed with the purpose of identifying the endogenous, exogenous, avoidable and unavoidable fractions of the exergy destruction. The latter was observed to be largely of endogenous nature, with the desorber and absorber being the major contributors. When the difference between the absorption and condensation temperatures was raised, both the first and second law efficiencies degraded. Furthermore, the absorber endogenous avoidable irreversibility was much larger than that at the desorber when the absorption temperature was lower than the condensation temperature, and the situation reversed when the absorption temperature became higher than the condensation temperature. The same trends were observed in terms of the exogenous avoidable exergy destruction. However, the endogenous unavoidable exergy destruction at the absorber was initially smaller than that at the desorber, and the two components equally contributed to the total endogenous unavoidable irreversibility when the absorption temperature became higher than the condensation temperature. 相似文献
4.
Spray quality is the critical factor which decides the efficacy of Small Quantity Lubrication (SQL) technology in a high specific energy involved machining process like grinding. Yet, the understanding about spray quality, the actual process mechanics and its effect on machining performance is inadequate. The present work is an attempt to establish a correlation between the spray input variables, quality of the spray and machining performance of SQL grinding through modelling and experiments. Using computational fluid dynamic techniques, the variation of droplet size, droplet velocity, number of droplets and heat transfer coefficient have been analysed at different input parameters and the computed trends have been verified and validated. CFD modelling of spray indicates that it is possible to produce aerosol medium with high heat dissipation ability at moderately high air pressure and low flow rate. It also shows that any increase in atomising air pressure favourably leads to notable increase in wetting area and also results in substantial enhancement in heat dissipation ability. Reduction of residual stress is thus remarkably good. On the other hand, grinding fluid flow rate, if increased, offers significantly better lubricity and reduces the grinding force which also reduces tensile residual stress. Short spell grinding test results are found to be in good agreement with CFD results. 相似文献
5.
李彩虹 《南京工业职业技术学院学报》2008,8(2):1-3
根据PET薄膜的特点和高分子熔融态流动理论,分析了挤出回收用螺杆的各段结构,及螺杆参数选择,设计出大长径比、深槽、双排气、高效专用螺杆。 相似文献
6.
《International Communications in Heat and Mass Transfer》2005,32(1-2):27-31
Pool boiling heat transfer from nano-porous surface immersed in a saturated FC-72 dielectric fluid has been experimentally studied at atmospheric pressure (101 kPa). The data obtained from nano-porous surface (Anodisc 25) of thickness about 70 μm made from aluminum oxide (Al2O3) obtained from Whatman, were compared to that of a plain surface (aluminum) of thickness about 105 μm. From the experimental data obtained it was evident that there is a reduction of about 30% in the incipient superheat for the applied power for nano-porous surface over plain surface. SEM photographs of the nano-porous coating were taken for determining the size of the pores. 相似文献
7.
This article presents a detailed investigation on the influence of the phosphorus element upon the laser sintering of a multicomponent
Cu-based metal powder system consisting of Cu, Cu-10Sn, and Cu-8.4P. Powder systems containing 0, 10, 15, and 20 wt pct CuP
were sintered in atmosphere at room temperature using the following optimal processing parameters: laser power of 350 W, scan
speed of 0.04 m/s, scan line spacing of 0.15 mm, and layer thickness of 0.25 mm. It was found that the relative density of
the sintered sample with 15 wt pct CuP increased by 24,4 pct as compared with the sample without phosphorus addition. A further
increase in the CuP content (≥20 wt pct), however, resulted in a poor densification with a serious delamination. The exact
metallurgical roles of the phosphorus element in the laser sintering process were addressed as follows. First, the phosphorus
could prevent the sintering system from oxidation by forming CuPO3, thereby improving the wetting characteristics and the sintering kinetics. Second, the phosphorus could decrease the surface
tension of molten materials, leading to a successive transition from highly discontinuous sintered tracks to fairly coherent
ones with increasing the phosphorus content. Third, the phosphorus could lower the melt viscosity, thereby improving the microstructural
homogeneity of the laser-sintered samples. 相似文献
8.
《International Journal of Fatigue》2007,29(9-11):1846-1854
This work presents a survey of the isothermal and anisothermal fatigue behavior of aluminum casting alloys obtained from different processes. Experimental results have shown that porosity, especially large and irregular pores, provides the main factor in decreasing fatigue properties of the tested alloys. In materials with similar porosity levels, other microstructural factors became relevant such as, matrix morphology and the amount of alloying elements. Fractographic analyses showed that fatigue cracks preferentially start to propagate in microcracks or interdendritic shrinkage usually located next to the surface. In most cases, propagation takes place in the eutectic phase, although in the thixoformed material, a transition from transgranular to intergranular mode was observed in the crack propagation mode. 相似文献
9.
A modified rainflow counting method 总被引:1,自引:0,他引:1
Nie Hong 《International Journal of Fatigue》1991,13(6):465-469
The rainflow counting method is commonly recognized to be a good cyclic counting method in fatigue life prediction and for testing engineering components and structures. However, it has some shortcomings, which are pointed out in this paper in connection with the analysis of the stress-strain response. A modified rainflow counting method is presented. Case studies show that all the cycles really existing in the stress-strain response that cannot be counted by the rainflow counting method can be counted by the modified rainflow counting method. So it can be said that the modified rainflow counting method is a more reasonable cycling counting method than the traditional rainflow counting method. 相似文献
10.
荀殿栋 《信息安全与通信保密》1996,(3)
Datacryptor 64E是数据包端一端保密机,用于保护经公用和专用X.25包交换网传输的敏感而有价值的信息。在传输之前先将数据加密,加密后的数据经网络传输,在其终点予以解密。 Datacryptor 64E仅对包的数据字段加密,地址和控制信息仍为明文,以保证数据包正确地通过网的路由传输。既然本设备用于端一端加密,这就意味着它仅安装在网络的终点处,而不是安装在每个网络的链路上。 相似文献