1,721,112 research outputs found
An Experimental Study of Thermophoretical Effects on the Small Particle Deposion from Combustion Gas Flows
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DEVELOPMENT OF THE ADVANCED PROCEDURE FOR EMERGENCY OPERATION USING TASK ALLOCATION AND SYNTHESIS OF PRA RESULTS
No full textAn advanced emergency operating procedure (AEOP) for emergency operation is developed and discussed by focusing attention on the importance of the operator's role in emergency conditions for nuclear power plants (NPPs). Progress and improvement in the procedures now seem to be at a standstill insofar as the remaining problems cannot apparently be solved using the conventional approach. To overcome the complexity of emergency operating procedures (EOPs) and maintain the consistency of action steps according to plant emergency conditions, operator tasks are allocated according to their duties in the AEOP and a computerized operator aided system (COAS) is developed as an alternative to reduce the operator's burden and provide the detail action procedures. The PRA (Probabilistic Risk Assessment) results are synthesized in the AEOP using the event tree (ET) to give awareness and prediction of accident progression in advance dynamically and COAS is implemented on a SUN-4/75 workstation using C and Quintus(TM) prolog language. Finally, the time response for completing the required action is observed to evaluate the impact of the AEOP with COAS on operator performance during the loss of offsite power (LOOP) scenario with the full scope simulator of NPP at Kori. The results indicated that operator actions using AEOP are not only more consistent but are also able to provide earlier termination and mitigation of accidents
DEVELOPMENT OF SEVERE ACCIDENT MANAGEMENT SUPPORTING SYSTEMS USING QUANTIFIED CONTAINMENT EVENT TREES
No full textThe Probabilistic Risk Analysis (PRA) for a nuclear power plant can provide so much valuable information including plant-specific vulnerabilities against severe accident, which is quite useful in developing severe accident management (SAM) strategies. In this study, the information regarding Containment Event Trees obtained by performing PRA is introduced to develop the suitable event-oriented SAM strategies. For these, it is crucial to identify the exact state of severe accident progression which is called Plant Damage State as an entrance condition. However, there are several areas where insufficient knowledge exists at the moment and thus it can be impossible to identify the event correctly. In this study, symptom-oriented strategies are also provided as an alternative methodology by using safety objective tree method to circumvent such drawback. Both event-oriented and symptom-oriented approaches are synthesized into a computerized supporting system for SAM, and linked with a severe accident simulator for on-line verification. A sample sequence is selected to show the simulated results performed by the system. Simulation results show that this kind of methodology might be quite useful in developing and implementing SAM strategies.
Effects of diethyl aluminum chloride (DEAC) addition to the catalysts prepared by reduction of TiCl4 with EtMgCl on ethylene-propylene copolymerization
No full textTiCl3/2.5MgCl2(0.5MgEt2)/THF catalyst (R) was prepared by the reduction of TiCl4 with EtMgCl. The effect of diethyl aluminum chloride (DEAC) addition on the catalytic activity in ethylene-propylene copolymerization was investigated. It was suggested from FT-i.r. that the catalyst R formed similar bimetallic (Ti-Mg-THF) complexes to the TiCl3(AA)/3MgCl2/THF catalyst (T3ME) of our previous report [7]. An ESR study provided evidence that the Ti3+ species in the catalyst R was of the multinuclear type, instead of an isolated type of T3ME, and it changed from a tetrahedral to an octahedral structure with addition of DEAC. The activities of R catalysts in copolymerization were more or less in the same order of magnitude with each other due to the multinuclear nature of the Ti3+ species, and the response to propylene comonomer decreased with addition of DEAC. The polydispersity of comonomer over R catalysts was in the range of 6-10, being much broader than that over the T3ME catalyst system. It might be due to the heterogeneity of the titanium(III) structure; tetrahedral as well as octahedral in R, instead of only octahedral in T3ME
Effects of Cr/Al underlayer on magnetic properties and crystallography in CoCrPtTa/Cr/Al thin films
No full textThe effects of Cr/Al underlayers on the magnetic properties of CoCrPtTa films deposited on glass substrates were investigated. The coercivity increased and the coercivity squareness decreased by using Cr/Al underlayers. The cause of the coercivity increase is attributed to the reduction of Co(0002) texture, the increase of magnetic isolation of CoCrPtTa grains, and the refinement of CoCrPtTa grains deposited on Cr/Al underlayers. The effects of an Al overlayer on the magnetic properties of CoCrPtTa/Cr films were also studied. The decrease of coercivity squareness is ascribed to the magnetic isolation of CoCrPtTa grains
Threshold-based camera motion characterization of MPEG video
No full textWe propose an efficient scheme for camera motion characterization in MPEG-compressed video. The proposed scheme detects six types of basic camera motions through threshold-based qualitative interpretation, in which fixed thresholds are applied to motion model parameters estimated from MPEG motion vectors (MVs). The efficiency and robustness of the scheme are validated by the experiment with real compressed video sequences
Model for the formation of active titanium complexes on MgCl2-ethyl benzoate-TiCl4catalysts for propylene polymerization
No full textCarbonyl (C-O) bonds of ethyl benzoate (EB) in the support and the catalysts were investigated by infrared (IR) spectroscopy, and a model for the MgCl2-EB-TiCl4 complex was proposed. The characteristic carbonyl peaks at 1690 cm-1 and 1636 cm-1 can be attributed to the carbonyl vibrations in linear EB-MgCl2 and bridged EB-MgCl2 complex, respectively. With small amounts of EB added to MgCl2, both linear and bridged EB/MgCl2 complexes are formed. A further increase in the amount of EB converts all of the complexes to the linear form. The active site for propylene polymerization seems to be the TiCl4-MgCl2 complex, generated by activation with TiCl4 of the bridged EB-MgCl2 complex, some of which is converted to the linear EB-MgCl2 complex. The linear EB-MgCl2 complex tends to inactivate the (EB-TiCl4)2 complex. The catalytic activity for propylene polymerization was consistent with the proposed model and the IR investigation
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