http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Multidisciplinary robust design optimization based on time-varying sensitivity analysis
Huanwei Xu,Wei Liao,Mufeng Li,Cong Hu,Suichuan Zhang,Xin Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3
The performance of complex mechanical systems often degrades over time primarily due to time-varying uncertainties. Improving the design of such systems entails addressing time-varying uncertainties through multidisciplinary design optimization (MDO). In this study, a multidisciplinary robust design optimization method that is based on time-varying sensitivity analysis is proposed. First, the indices for the time-varying reliability sensitivity of limit state functions are calculated by combining sensitivity analysis and an empirical correction formula. The propagation effects of these time-varying uncertainties are qualified by combining the simplified implicit uncertainty propagation and sequential quadratic programming methods. Finally, the robust design method is integrated with MDO to reduce the effects of time-varying uncertainties. The feasibility and effectiveness of the proposed method are illustrated with a mathematical problem and an engineering example.
李羲泰(Hee-Tae Lee),文鍾必(Jong-Fil Moon),金載哲(Jae-Chul Kim) 대한전기학회 2006 전기학회논문지A Vol.55 No.11
The failure prediction and preventive maintenance for the equipment of nuclear power plant area using reliability-centered maintenance have been grown. On the other hand, the maintenance for power distribution system consists of time-based maintenance mainly. In this paper, the new maintenance algorithms for power distribution system are developed considering reliability indices. First of all, Time-varying failure rates are extracted from data accumulated at KEPCO using exponential distribution function and wei bull distribution function. Next, based on the extracted failure rate, reliability for real power distribution system is evaluated for applying the effective maintenance algorithm which is the analytic method deciding the maintenance point of time and searching the feeder affecting the specific customer. Also the algorithm deciding the maintenance priority order are presented based on sensitivity analysis and equipment investment plan are analyzed through the presented algorithm at real power distribution system.
Kim, Su Jin,Sullivan, Jenna M,Wang, Shuo,Cosgrove, Kelly P,Morris, Evan D BlackWell Publishing Ltd 2014 HUMAN BRAIN MAPPING Vol.35 No.9
<P>The “linear parametric neurotransmitter PET” (lp-ntPET) model estimates time variation in endogenous neurotransmitter levels from dynamic PET data. The pattern of dopamine (DA) change over time may be an important element of the brain's response to addictive substances such as cigarettes or alcohol. We have extended the lp-ntPET model from the original region of interest (ROI) - based implementation to be able to apply the model at the voxel level. The resulting endpoint is a dynamic image, or movie, of transient neurotransmitter changes. Simulations were performed to select threshold values to reduce the false positive rate when applied to real <SUP>11</SUP>C-raclopride PET data. We tested the new voxelwise method on simulated data, and finally, we applied it to <SUP>11</SUP>C-raclopride PET data of subjects smoking cigarettes in the PET scanner. In simulation, the temporal precision of neurotransmitter response was shown to be similar to that of ROI-based lp-ntPET (standard deviation ∼ 3 min). False positive rates for the voxelwise method were well controlled by combining a statistical threshold (the <I>F</I>-test) with a new spatial (cluster-size) thresholding operation. Sensitivity of detection for the new algorithm was greater than 80% for the case of short-lived DA changes that occur in subregions of the striatum as might be the case with cigarette smoking. Finally, in <SUP>11</SUP>C-raclopride PET data, DA movies reveal for the first time that different temporal patterns of the DA response to smoking may exist in different subregions of the striatum. These spatiotemporal patterns of neurotransmitter change created by voxelwise lp-ntPET may serve as novel biomarkers for addiction and/or treatment efficacy.</P>
현재 소득에 따라 소비하는 가계의 비율에 대한 변화 추이 연구
김윤미 ( Yun Mi Kim ) 한국경제통상학회 2012 경제연구 Vol.30 No.2
This paper investigates the time-varying nature of the excess sensitivity of consumption to income. Using a recently proposed estimation method on time-varying parameter models, we have discovered that the excess sensitivity has been gradually decreased over the period of 1953 through 2006 in the US. One potential explanation for this finding is that the gradual developments and improvements in the financial system could have lessened liquidity constraints, such that consumers have become less restricted by their current income level.