Failure investigation was carried out on boiler water wall tubes of a thermal power plant through visual inspection, chemical analysis, and metallurgical analysis. Failure was in the form of thin/micro cracks along the length of the tubes which were located at the girth welding joint of tubes. Experimental results revealed that the cracking was from inward to outward of the tube thickness. Discontinuities/cavities were observed in the welded region which might have occurred due to lack of fusion of base metal and the weld metal. Cracks were initiated from the sharp corner/crack tip of the cavities/discontinuities present at the welded region under the action of hoop/thermal stress existed during the operation. Nature of the crack propagation indicates the case of typical hydrogen-induced cracking. Moreover, the presence of the cavities/discontinuities reduced the cross-sectional area of tubes resulting increased stress intensity. Increased stress beyond the flow stress of the material assisted by hydrogen-induced effect resulted the cracking of the tubes. In order to mitigate the problem, proper welding of tubes joints should be carried out followed by proper inspection after weld. Secondly, hydrogen dissolution during welding should be prevented and treatment for its removal after welding should be carried out. 相似文献
A re-configurable, QoS-enhanced intelligent stochastic real-time optimal fair packet scheduler, QUEST, for IP routers is proposed and investigated. The objective is to maximize the system QoS subject to the constraint that the processor utilization is kept at 100%. All past work on router schedulers for multimedia traffic were of earlier generation, in that they focused on maximizing utilization whereas being QoS-aware but without explicitly maximizing the QoS. Keeping utilization fixed at nearly 100%, QoS is dynamically maximized, thus moving to the next generation. QUEST’s other unique advantages are three-fold. First, it solves the challenging problem of starvation for low priority processes; second, it solves the major bottleneck of Earliest Deadline First scheduler’s failure at heavy traffic loads. Finally, QUEST offers the benefit of arbitrarily pre-programming the process utilization ratio. Three classes of multimedia IP traffic, namely, VoIP, IPTV and HTTP have been considered. Two most important QoS metrics, namely, packet loss rate (PLR) and mean waiting time, are addressed. All claims are supported by discrete event and Monte Carlo simulations. The proposed scheduler outperforms benchmark schedulers and offers 37% improvement in packet loss rate and 23% improvement in mean waiting time over the best competing current scheduler Accuracy-aware EDF. The proposed scheduler was validated in a test-bed platform of a NetFPGA® router and results were observed with Paessler® PRTG network monitor.
Knowledge gained through classification of microarray gene expression data is increasingly important as they are useful for phenotype classification of diseases. Different from black box methods, fuzzy expert system can produce interpretable classifier with knowledge expressed in terms of if-then rules and membership function. This paper proposes a novel Genetic Swarm Algorithm (GSA) for obtaining near optimal rule set and membership function tuning. Advanced and problem specific genetic operators are proposed to improve the convergence of GSA and classification accuracy. The performance of the proposed approach is evaluated using six gene expression data sets. From the simulation study it is found that the proposed approach generated a compact fuzzy system with high classification accuracy for all the data sets when compared with other approaches. 相似文献
Being innocuous, nanodiamonds find huge applications in bioimaging, drug delivery and biomedical sensing. Their synthesis is generally carried out by detonation or shock wave methods. This article reports novel, economical and risk-free extraction of nanodiamonds from carbonaceous waste (smoke deposits of Hawan kund). Structural and morphological studies of extracted material revealed that the nanodiamonds have a size range of 4–5 nm and consists of sp3 core and sp2 shell. Extracted nanodiamonds contain various functional groups on its surface which make it suitable for various applications. Cytotoxicity assay revealed very less toxicity of extracted nanodiamonds, which makes them suitable candidate for biological applications. The proposed method offers the possibility of economical and detonation free production of nanodiamonds. 相似文献
Journal of Inorganic and Organometallic Polymers and Materials - Nanocomposite polymer electrolyte (NCPE) films based on a blend of two polymers poly (ethylene oxide) (PEO) and poly (vinylidene... 相似文献