The Topology ToolKit

This system paper presents the Topology ToolKit (TTK), a software platform designed for topological data analysis in scientific visualization. TTK provides a unified, generic, efficient, and robust implementation of key algorithms for the topological analysis of scalar data, including: critical points, integral lines, persistence diagrams, persistence curves, merge trees, contour trees, Morse-Smale complexes, fiber surfaces, continuous scatterplots, Jacobi sets, Reeb spaces, and more. TTK is easily accessible to end users due to a tight integration with ParaView. It is also easily accessible to developers through a variety of bindings (Python, VTK/C++) for fast prototyping or through direct, dependence-free, C++, to ease integration into pre-existing complex systems. While developing TTK, we faced several algorithmic and software engineering challenges, which we document in this paper. In particular, we present an algorithm for the construction of a discrete gradient that complies to the critical points extracted in the piecewise-linear setting. This algorithm guarantees a combinatorial consistency across the topological abstractions supported by TTK, and importantly, a unified implementation of topological data simplification for multi-scale exploration and analysis. We also present a cached triangulation data structure, that supports time efficient and generic traversals, which self-adjusts its memory usage on demand for input simplicial meshes and which implicitly emulates a triangulation for regular grids with no memory overhead. Finally, we describe an original software architecture, which guarantees memory efficient and direct accesses to TTK features, while still allowing for researchers powerful and easy bindings and extensions. TTK is open source (BSD license) and its code, online documentation and video tutorials are available on TTK's website

Prioritizing the Maintenance of Pipeline Based on Risk Analysis

There have been a number of incidences reported for pipeline failures at both onshore and offshore facilities. In order to minimize the failure causes, it is required to clearly understand the failure mechanism, probability and consequences of failure and also the methodology for data to be analyzed. This thesis was based on an Analytical Hierarchy Process (AHP) to determine the risk factors of pipeline failure. AHP provide a multiple criteria scoring results based on expert judgment for prioritizing the maintenance of the pipeline. To perform the AHP approach, two pipeline systems have been chosen for case studies was located in Kertih, Malaysia and Kutai Basin, Indonesia. Analysis of the AHP process showed that the gas pipeline in Kertih involves greatest risk failure covers probabiliy and consequences. The highest probability is internal corrosion of 41.7% and the rest is caused by internal erosion of 19.1%, external impacts of 13.8 %, external corrosion of 10.7%, free span of 8.1%, and on bottom stability of 6.7%. The greatest consequences of pipeline failure would impact on the environment of 59.4%, and the others will be the impact on economic of 24.9% and safety of 15%. On the other hand the highest probability for oil pipeline at Kutai Basin is caused by system operation of 34.7% and the other factors are design index of 23.7%, maintenance of 23.7%, and third party index of 18%. The greatest consequences will be on business of 60%, the second impact is environment of 20% and the last impact is on population of 20%. Based on these two pipelines systems then the moderation for probability and consequence of failure have been determined. The result of analysis shows in general the factor of probability and consequence of failure are similar in various pipeline areas. By clearly knowing and understanding the probability and consequences of pipeline failure, then the risk level and category can be determined. From this analysis the pipelines can be ranked according to risk will assists the prioritization of pipelines maintenance. The inspection and maintenance budgets would be more effectively plan by setting priorities based on these pipelines risk. Those pipelines with higher risk should be given more urgent attention for maintenance action while those with lower risk rank may be put on a waiting list. The AHP method has been compared to the existing method in formulating the pipeline maintenance, from the analysis the detail and complete result for AHP has been showed. AHP can exactly show the factors that may cause the pipeline failure based on the structure of hierarchy of risk pipeline failure and categorize the risk into risk category so that proper maintenance can be determined. Where as in the existing method the maintenance plans only based on inspection and comparison of each factor has not been made. This practice will result in improper maintenance which may incur unnecessary cost