Catastrophic floods in Kosi catchment during August 2008

A breach in embankment of Kosi barrage was reported on 18 August, 2008 which has changed its course and resulted in a fresh channel around 120 km to the east of its previous channel. At the time of failure of the embankment, gushing out of about 2832 m3/s water with great impact breaking into the Mahendra Rajmarg and then taking a southward route into the old 1892-1921 abandoned course of the river, thus leaving the pre-breach C-loop and following a straight route to the Ganga. In this study meteorological aspect are analysed in details in relation to the catastrophic flood in the Kosi river catchment during August 2008. It seems that this catastrophic flood may not be solely due to rainfall in the catchment of Kosi. The breach is due to incorrect strategies of river management, human negligence and poor maintenance of afflux bund of the barrage (Sinha, 2009).

Ice on Suspension Bridge Cables

In this report we study mathematical models for predicting when ice may form and fall from vertical steel hangers of suspension bridges down onto the road below. This is an important problem to study, not only because of the economic costs related to closing a bridge due to the risk of falling ice, but also the human cost if the bridge is still open to traffic when ice falls down. In the report we present two main categories of models for predicting falling times: 1) models based on heat transfer from the surrounding air, and 2) models based on heating due to radiation from the sun. A flow chart is furthermore presented together with tables for determining which model to use and quickly estimating time of failure based on a set of simple conditions.

Research on the Fast and Accurate Estimation Method of Sag Voltage

Sag voltage affects the quality of the grid voltage and the working conditions of the electrical equipment. In order to prevent effectively this problem, the authors investigated the estimation method of fast and accurate voltage and phase angle in the presence of sag voltage. The method proposed Least Error Squares (LES) were constructed on the basis of the least squares algorithm and Taylor series expansion. Compared with conventional Clark and Park methods, the LES approach has the following major advantages: faster detection time, reduced deviation of estimated voltage values at the time of failure; faster detection time, reduced deviation of estimated voltage values at the time of failure; being not affected by other fundamental components 50Hz, the DC components in the grid. The effectiveness of the method is verified by simulation model of a distribution grid in Vinh Phuc province by Matlab / SIMULINK software.

Time-of-Failure Probability Mass Function Computation Using the First-Passage-Time Method Applied to Particle Filter-based Prognostics

One of the main challenges in prognostics corresponds to the estimation of a system’s probability density function (PDF) for the time-of-failure (ToF) prior to reach a fault condition. An appropriate characterization of the ToF-PDF will let the user know about the remaining useful life of the system or component, allowing the users to prevent catastrophic failures through optimal maintenance schedules. However, the ToF-PDF estimation is not an easy task because it involves both the computation of long-term predictions of a fault indicator of the system and the definition of the hazard zone. In most cases, the trajectory of the fault indicator is assumed as a trajectory with monotonic behavior, and the hazard zone may be considered as a deterministic or probabilistic threshold. This monotonic behavior of the fault indicator enables assuming that the system will only fail once when this indicator reaches the hazard zone, and the ToF-PDF will be estimated according to mathematical definitions proposed in the state-of-the-art. Nevertheless, not all the fault indicators may be considered with a monotonic behavior due to its nature as a stochastic process or regeneration phenomenon, which may entail to errors in the ToF-PDF estimation. To overcome this issue, this paper presents an approach for the estimation of the ToF-PDF using the first-passage-time (FPT) method. This method is focused on the computation of the FPT-PDF when the stochastic process under analysis reaches a specified threshold for the first time only. Accordingly, this work aims to analyze the impact in the estimation of the ToF-PMF (probability mass function) when particle-filter-based prognostics algorithms are used to perform long-term predictions of the fault indicator and compute the probability of failure considering specific hazard zones (which may be characterized by a deterministic value or by a failure likelihood function). A hypothetical self regenerative degradation process is used as a case study to evaluate the performance of the proposed methods.

Conversations in Caves

This paper takes the form of a discussion between Flora Parrott (an artist) and Harriet Hawkins (a geographer) who first brought together their existing interests in caves and the underground in 2015. Gully Cave, a site of their shared “field-work” and two experimental workshops offer the chance to reflect on their evolving work together. This exchange, edited from a series of emails, has the sort of evolving, looping form their collaboration has taken, circling around key themes including; the importance of time, of failure and trust in the process of development and discussions around expertise and experimentation.

Making power emerge: municipalism and the right to the city

Although the end of 2019 will be remembered by many as a time of failure, the last few years have also been a time of hope. This article draws lessons from the internationalist municipalist movement, and frames these experiences through the concepts of autogestion and the Right to the City. Municipalist political strategies can provide a radical re-articulation of this hope: to argue for a municipalist politics is to argue for place-based strategies that transform our relationship to our territories, with a focus on making new forms of power emerge. It is not an alternative to national and international perspectives, but rather the development of new ways of acting on these perspectives. Establishing the difference between progressive local government policy and a municipalist agenda, the article concludes by offering five propositions for the development of a municipalist coordination in one British city - Manchester.