Improvements to the RELAP5/MOD3 reflood model and uncertainty quantification of reflood peak clad temperature

Assessment of the original REAP/N4OD3.1 code against the FLECHT SEASET series of experiments has identified some weaknesses of the reflood model, such as the lack of a quenching temperature model, the shortcoming of the Chen transition boiling model, and the incorrect prediction of droplet size and interfacial heat transfer. Also, high temperature spikes during the reflood calculation resulted in high steam flow oscillation and liquid carryover. An effort had been made to improve the code with respect to the above weakness, and the necessary model for the wall heat transfer package and the numerical scheme had been modified. Some important FLECHT-SEASET experiments were assessed using the improved version and standard version. The result from the improved REAP/MOD3.1 shows the weaknesses of REAP/N4OD3.1 were much improved when compared to the standard MOD3.1 code. The prediction of void profile and cladding temperature agreed better with test data, especially for the gravity feed test. The scatter diagram of peak cladding temperatures (PCTs) is made from the comparison of all the calculated PCTs and the corresponding experimental values. The deviation between experimental and calculated PCTs were calculated for 2793 data points. The deviations are shown to be normally distributed, and used to quantify statistically the PCT uncertainty of the code. The upper limit of PCT uncertainty at 95% confidence level is evaluated to be about 99K

Identification of SYK inhibitor, R406 as a novel senolytic agent

The selective removal of senescent cells by senolytics is suggested as a potential approach to reverse aging and extend lifespan. Using high-throughput screening with replicative senescence of human diploid fibroblasts (HDFs), we identified a novel senolytic drug R406 that showed selective toxicity in senescent cells. Using flow cytometry and caspase expression analysis, we confirmed that R406 caused apoptotic cell death along with morphological changes in senescent cells. Interestingly, R406 altered the cell survival-related molecular processes including the inhibition of phosphorylation of the focal adhesion kinase (FAK) and p38 mitogen-activated protein kinase (MAPK) in senescent cells. This pattern was not observed in other known senolytic agent ABT263. Correspondingly, apoptotic cell death in senescent cells was induced by simultaneously blocking the FAK and p38 pathways. Taken together, we suggest that R406 acts as a senolytic drug by inducing apoptosis and reducing cell attachment capacity. © Cho et al.1

Sub-optimal feedback control using a successive galerkin-wavelet algorithm

We present a numerical algorithm for solving the Hamilton-Jacobi Bellman equation using a successive Galerkin-wavelet projection scheme. According to this scheme,the so-called Generalized-Hamilton-Jacobi-Bellman (GHJB) equation is solved iteratively starting from a stabilizing solution. As basis function for the Galerkin projections we consider the antiderivatives of the well-known Daubechies ’ wavelets. Wavelets offer several advantages over traditional bases functions such as time-frequency localization and compact support. A numerical example illustrates the proposed approach.

Approximations to Optimal Feedback Control Using a Successive Wavelet Collocation Algorithm

Wavelets, which have many good properties such as time/freqency localization and compact support, are considered for solving the Hamilton-Jacobi-Bellman (HJB)equation as appears in optimal control problems. Specifically, we propose a Successive Wavelet Collocation Algorithm (SWCA)that uses interpolating wavelets in a collocation scheme to iteratively solve the Generalized-Hamilton-Jacobi-Bellman (GHJB)equation and the corresponding optimal control law. Numerical examples illustrate the proposed approach.

AAS 03-575 Solving

optimal control problems with generating function

Development of fast RF spectrometer system for MHD detection

During the 2010 KSTAR plasma experiment, unidentified spiky RF pulses (< 3 GHz, similar to 10 mu s) were detected by an electron cyclotron emission imaging (ECEI) system at the occurrence of large MHD instabilities such as edge localized modes (ELMs). A fast RF spectrometer system has been constructed for direct detection of the RF radiation in the range of 0.5 similar to 3.0 GHz to study the spectral evolution of the RF spikes in more detail.X1153sciescopu