Mechanical Behavior of Steel Pipe Bends; An Overview.

An overview of the mechanical behavior of steel pipe (elbows) is offered, based on previously reported analytical solutions, numerical results, and experimental data. The behavior of pipe bends is characterized by significant deformations and stresses, quite higher than the ones developed in straight pipes with the same cross section. Under bending loading (in-plane and out-of-plane), the main feature of the response is cross-sectional ovalization, which influences bending capacity and is affected by the level of internal pressure. Bends subjected to cyclic in-plane bending exhibit fatigue damage, leading to base metal cracking at the elbow flank. Using advanced finite-element tools, the response of pipe elbows in buried pipelines subjected to ground-induced actions is also addressed, with emphasis on soil-pipeline interaction. Finally, the efficiency of special-purpose finite elements for modeling pipes and elbows is briefly discussed. © 2016 by ASME

Large-scale meridional and zonal variability in the nitrogen isotopic composition of plankton in the Atlantic Ocean

The zonal (ca. 15º-40ºW along 26-29ºN) and meridional (ca. 30ºN-30ºS along 28º-29ºW) variability of δ15N of suspended particles and zooplankton (>40 µm) was studied to assess the influence of nitrogen fixation in the isotopic budget of the tropical and subtropical Atlantic ocean. Two cruises were conducted in October-November 2007 and April-May 2008 comprising a zonal and meridional transect each. In the region between 30º-15ºN, the concurrently measured nitrogen fixation was insufficient to explain the consistent patch of suspended particles with δ15N < 2‰ and points to a significant contribution of atmospheric deposition of light nitrogen to the isotopic budget. The equatorial region (15ºN-10ºS) is subject to intense nitrogen fixation, which, according to a two-end-member mixing model, may explain 40-60% of the observed δ15N in suspended particles and 3-30% in zooplankton. In the South region between 10ºS-30ºS, low values (<4‰) were measured in suspended particles and zooplankton during 2008. The values of δ15N of suspended particles suggest that nitrogen fixation, which is usually low (<10 µmol N m−2 d−1), may represent 50-60% of phytoplankton nitrogen in this region. Hence, diazotrophy in the South Atlantic may be more important than previously thought.Minsiterio de Ciencia y Tecnología (CTM2004-05174-C01 and CTM2004-05174-C02), Xunta de Galicia PGIDIT05PXIC31201PNPreprint1,749

Review and Evaluation of the J100â 10 Risk and Resilience Management Standard for Water and Wastewater Systems

Risk analysis standards are often employed to protect critical infrastructures, which are vital to a nation’s security, economy, and safety of its citizens. We present an analysis framework for evaluating such standards and apply it to the J100â 10 risk analysis standard for water and wastewater systems. In doing so, we identify gaps between practices recommended in the standard and the state of the art. While individual processes found within infrastructure risk analysis standards have been evaluated in the past, we present a foundational review and focus specifically on water systems. By highlighting both the conceptual shortcomings and practical limitations, we aim to prioritize the shortcomings needed to be addressed. Key findings from this study include (1) risk definitions fail to address notions of uncertainty, (2) the sole use of â worst reasonable caseâ assumptions can lead to mischaracterizations of risk, (3) analysis of risk and resilience at the threatâ asset resolution ignores dependencies within the system, and (4) stakeholder values need to be assessed when balancing the tradeoffs between risk reduction and resilience enhancement.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154262/1/risa13421_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154262/2/risa13421.pd

Design of Pressure Vessels and Piping

[no abstract provided]https://fount.aucegypt.edu/faculty_book_chapters/1135/thumbnail.jp