Development of a software tool for reliability estimation

This thesis presents Version 2.0 of Software Tool for Reliability Estimation (STORE 2.0). It expands on the work done by Parekh [1] by revising the algorithm for tie-set and cut-set calculation, by including fault tree reliability analysis, by analyzing state dependent system, and by integrating component and system reliability analysis.;This thesis also presents an approach to the simplification of complex systems by collapsing series and parallel components into a sub-system. The approach was illustrated on an example described by Nelson et al. [2]. The example had 16 components resulting in ten cut-sets and fifty five tie-sets. Upon simplification, the problem was reduced to one tie-set only.;STORE 2.0 integrates parameter estimation, component reliability analysis, system reliability analysis, estimation of reliability of state dependent systems, and fault tree analysis. It was verified and validated on several examples taken from the open literature. The software was developed in Visual Basic 2008 with SQL as the database

Connectivity-Preserving Swarm Teleoperation With A Tree Network

During swarm teleoperation, the human operator may threaten the distance-dependent inter-robot communications and, with them, the connectivity of the slave swarm. To prevent the harmful component of the human command from disconnecting the swarm network, this paper develops a constructive strategy to dynamically modulate the interconnections of, and the locally injected damping at, all slave robots. By Lyapunov-based set invariance analysis, the explicit law for updating that control gains has been rigorously proven to synchronize the slave swarm while preserving all interaction links in the tree network. By properly limiting the impact of the user command rather than rejecting it entirely, the proposed control law enables the human operator to guide the motion of the slave swarm to the extent to which it does not endanger the connectivity of the swarm network. Experiment results demonstrate that the proposed strategy can maintain the connectivity of the tree network during swarm teleoperation

PL-MODT and PL-MODMC : two codes for reliability and availability analysis of complex technical systems using the fault tree modularization technique

"November 1978."Includes bibliographical referencesThe methodology used in the PL-MOD code has been extended to include the time-dependent behavior of the fault tree components. Four classes of components are defined to model time-dependent fault tree leaves. Mathematical simplifications are applied to predict the time-dependent behavior of simple modules in the fault tree from its input components' failure data. The extended code, PL-MODT, handles time-dependent problems based on the mathematical models that have been established. An automatic tree reduction feature is also incorporated into this code. This reduction is based on the Vesely-Fussell importance measure that the code calculates. A CUT-OFF value is defined and incorporated into the code. Any module or component in the fault tree whose V-F importance is less than this value will automatically be eliminated from the tree. In order to benchmark the PL-MODT code, a number of systems are analyzed. The results are in good agreement with other codes, such as FRANTIC and KITT. The computation times are comparable and in most of the cases are even lower for the PL-MODT code compared to the others. In addition, a Monte-Carlo simulation code (PL-MODMC) is developed to propagate uncertainties in the failure rates of the components to the top event of a fault tree. An efficient sorting routine similar to the one used in the LIMITS code is employed in the PL-MODMC code. Upon modularization the code proceeds and propagates uncertainties in the failure rates through the tree. Large fault trees such as the LPRS fault tree as well as some smaller ones have been analyzed for simulation, and the results for the LPRS are in fair agreement with the WASH-1400 predictions for the number of simulations performed. The codes PL-MODT and PL-MODMC are written in PL/l language which offers the extensive use of the list processing tools. First experience indicates that these codes are very efficient and accurate, specifically for the analysis of very large and complex fault treesSponsored by the NR

Insights into the mechanism of diurnal variations in methane emission from the stem surfaces of Alnus japonica

木の中にガスパイプライン？ --ガス漏れの場所を特定せよ！--. 京都大学プレスリリース. 2022-07-15.Recent studies have suggested that in certain environments, tree stems emit methane (CH₄). This study explored the mechanism of CH₄ emission from the stem surfaces of Alnus japonica in a riparian wetland. Stem CH₄ emission rates and sap flux were monitored year-round, and fine-root anatomy was investigated. CH₄ emission rates were estimated using a closed-chamber method. Sap flux was measured using Granier-type thermal dissipation probes. Root anatomy was studied using both optical and cryo-scanning electron microscopy. CH₄ emissions during the leafy season exhibited a diurnally changing component superimposed upon an underlying continuum in which the diurnal variation was in phase with sap flux. We propose a model in which stem CH₄ emission involves at least two processes: a sap flux-dependent component responsible for the diurnal changes, and a sap flux-independent component responsible for the background continuum. The contribution ratios of the two processes are season-dependent. The background continuum possibly resulted from the diffusive transport of gaseous CH₄ from the roots to the upper trunk. Root anatomy analysis indicated that the intercellular space of the cortex and empty xylem cells in fine roots could serve as a passageway for transport of gaseous CH₄

An Algebraic Classification of Exceptional EFTs Part II: Supersymmetry

We present a novel approach to classify supersymmetric effective field theories (EFTs) whose scattering amplitudes exhibit enhanced soft limits. These enhancements arise due to non-linearly realised symmetries on the Goldstone modes of such EFTs and we classify the algebras that these symmetries can form. Our main focus is on so-called exceptional algebras which lead to field-dependent transformation rules and EFTs with the maximum possible soft enhancement at a given derivative power counting. We adapt existing techniques for Poincar\'{e} invariant theories to the supersymmetric case, and introduce superspace inverse Higgs constraints as a method of reducing the number of Goldstone modes while maintaining all symmetries. Restricting to the case of a single Goldstone supermultiplet in four dimensions, we classify the exceptional algebras and EFTs for a chiral, Maxwell or real linear supermultiplet. Moreover, we show how our algebraic approach allows one to read off the soft weights of the different component fields from superspace inverse Higgs trees, which are the algebraic cousin of the on-shell soft data one provides to soft bootstrap EFTs using on-shell recursion. Our Lie-superalgebraic approach extends the results of on-shell methods and provides a complementary perspective on non-linear realisations