Pipeline Rockberm Design Principles for UHB Mitigation

2019 ◽  
Author(s):  
M. Liu ◽  
C. Cross
Keyword(s):  
Theoretical Analysis ◽  
Structural Reliability ◽  
Design Principle ◽  
Failure Mechanisms ◽  
Vertical Direction ◽  
Analytical Models ◽  
Soil Types ◽  
The Common ◽  
Uplift Resistance ◽  
Mitigation Design

Abstract Rockdumping may be necessary for pipeline UHB mitigation, crossings for separation, protection and stability. It is imperative that the structural reliability analysis for UHB is assessed with all aspects and factors taken into account to predict accurately the amount of rock and download required to ensure the integrity of pipelines. For UHB mitigation design, there are a number of analytical models available for download calculations to determine rockdump schedule. This paper examines and highlights some fundamental issues and pitfalls for rockberm design with respect to UHB download assessment. The lateral breakout has been previously addressed by some engineers and researchers. The potential risk for pipe to breakout from the rockberm is studied herein focusing on the vertical direction due to upheaval load. Based on the theoretical analysis and numerical FEA modelling, it is demonstrated that the common practice for rockbern design is not consistent resulting in unconservative rockdumping for UHB stability. Further design optimization can be compromised by lack of understanding of the failure mechanisms. Uplift resistance for stratified and layered soil types applicable for rock enhancement is also discussed and formulated. The design principle and rationale for selecting an appropriate rockberm profile and its sizing is proposed. Its effect on the UHB is illustrated by a detailed theoretical analysis and a series of numerical simulations with respect to pipeline dimensions.

UHB Design Approach for Multiple Pipelines Installed in Shared Trench

2019 ◽  
Author(s):  
M. Liu ◽  
C. Cross
Keyword(s):  
Proximity Effect ◽  
Burial Depth ◽  
Field Development ◽  
Upheaval Buckling ◽  
Resistance Reduction ◽  
Failure Angle ◽  
The Common ◽  
Uplift Resistance ◽  
Mitigation Design ◽  
Offshore Field

Abstract Upheaval buckling (UHB) mitigation for trenched and buried pipelines can constitute a substantial cost element for offshore field development. There appears to have a variety of reasons for dual or more pipelines and umbilicals to be considered for installation inside the same trench. A single shared trench has been used for multiple pipelines not only for cost saving, but especially when constrained and driven by route corridor challenges. The common practice for dual pipeline trenching and UHB design is to either perform UHB design independently without due consideration of the pipelines in the proximity, potentially resulting in a compromised UHB mitigation design, or simply combine the uplift resistance required for each individual pipeline in the proximity to obtain the overall backfill/rock dumping to account for pipeline interactions. This paper re-examines the rationale of the normal practice and some fundamental aspects of UHB design for dual pipelines installation inside the same trench. The proximity effect on the uplift resistance is investigated with respect to pipeline spacing and burial depth. Its impact on the UHB mitigation is considered by a detailed analysis and a series of parametric simulations with respect to pipeline dimensions and gaps. The sensitivity of the soil slip failure angle and the dilatancy is also performed. Based on the theoretical analysis and FEA modelling, a model solution is formulated and proposed for evaluating uplift resistance reduction for multiple lines. The formulae are extended to deal with multi-layered soil and rockdump. A number of pipeline configurations have been discussed including a piggyback arrangement. A robust UHB mitigation and reduced optimum rockdumping can be achieved by considering the proximity effect through challenging the industry norms and common approach.

Methodology for Analysis of Schottky Diode Failures

2010 ◽  
Author(s):  
Bhanu P. Sood ◽  
Michael Pecht ◽  
John Miker ◽  
Tom Wanek
Keyword(s):  
Failure Mode ◽  
Schottky Diode ◽  
Failure Modes ◽  
Schottky Diodes ◽  
Failure Mechanisms ◽  
Forward Voltage ◽  
Fast Switching ◽  
Voltage Drops ◽  
The Common

Abstract Schottky diodes are semiconductor switching devices with low forward voltage drops and very fast switching speeds. This paper provides an overview of the common failure modes in Schottky diodes and corresponding failure mechanisms associated with each failure mode. Results of material level evaluation on diodes and packages as well as manufacturing and assembly processes are analyzed to identify a set of possible failure sites with associated failure modes, mechanisms, and causes. A case study is then presented to illustrate the application of a systematic FMMEA methodology to the analysis of a specific failure in a Schottky diode package.

scholarly journals Developing Soft Skills among Potential Employees: A Theoretical Review on Best International Practices

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Oleksandr Malykhin ◽  
Nataliia Oleksandrivna Aristova ◽  
Liudmyla Kalinina ◽  
Tetyana Opaliuk
Keyword(s):  
Professional Development ◽  
Theoretical Analysis ◽  
Soft Skills ◽  
The Other ◽  
Skills Development ◽  
Common Language ◽  
The Common ◽  
The One ◽  
A Company ◽  
Selection Of

The present paper addresses the issue of determining the best international practices for developing soft skills among students of different specialties through carrying out a theoretical review. Basing on literature on present-day theory the authors make an attempt to explain soft skills dichotomies, summarize existing approaches to classifying soft skills, consolidate and document best international practices for soft skills development among potential employees of different specialties including bachelor students, master students, doctoral and postdoctoral students. The data obtained in the theoretical analysis reveal that the possible ambiguities in the interpretation of the concept of “soft skills” are caused, on the one hand, by the dichotomic perception of their nature by present-day researchers and educators and, on the other hand, by the absence of the common language which makes it difficult to provide a more unified definition most satisfactory to all concerned. The authors are convinced that soft skills have a cross-cutting nature and regard them as personal and interpersonal meta-qualities and meta-abilities that are vital to any potential employee who is going to make positive contributions not only to his/her professional development but to the development of a company he/she is going to work for. The results of the conducted theoretical review clearly indicate that the absence of the unified understanding of the concept of “soft skills” is reflected in the existence of different approaches to classifying soft skills, let alone, the selection of didactic tools for developing soft skills among potential employees.

scholarly journals Third Report on a Forest Survey of Illinois

1926 ◽  
Vol 16 (1-7) ◽  
pp. 1-102 ◽  
Author(s):  
Clarence Telford
Keyword(s):  
Natural History ◽  
The State ◽  
Soil Types ◽  
Forest Survey ◽  
The Common ◽  
History Survey

The State Natural History Survey has undertaken an inventory of the forests, and the purpose of this report is to present the area and condition of the forests of Illinois, and to show the productiveness of the common soil types in terms of forest crops.

The Technology Study of New Asymmetrical Half-Bridge Converter

2014 ◽  
Vol 986-987 ◽  
pp. 1884-1887
Author(s):  
Yue Fen Wu
Keyword(s):  
Theoretical Analysis ◽  
Control Strategy ◽  
Bridge Circuit ◽  
Technology Study ◽  
Soft Switch ◽  
Dc Bias ◽  
The Common ◽  
Simulation Results

Because the shortcomings of the common asymmetrical half-bridge circuit can't achieve soft switch and has DC bias for the transformer, the paper studies a new asymmetrical half-bridge circuit. Compared with the traditional asymmetrical half-bridge circuit, the circuit is added an auxiliary switch and diode by the composition of the slip. Thus the converter can achieve the control strategy of symmetric PWM. At last the simulation results show that the theoretical analysis is correct.

scholarly journals Country-scale InSAR monitoring for settlement and uplift damage calculation in architectural heritage structures

2020 ◽  
pp. 147592172094212
Author(s):  
Anastasios Drougkas ◽  
Els Verstrynge ◽  
Koenraad Van Balen ◽  
Michal Shimoni ◽  
Thibauld Croonenborghs ◽  
...  
Keyword(s):  
Ground Movement ◽  
Analytical Models ◽  
Building Structures ◽  
Architectural Heritage ◽  
Damage Classification ◽  
General Applicability ◽  
Combined Use ◽  
Building Geometry ◽  
Different Types ◽  
The Common

The article proposes a methodology for assessing the development of damage in building structures, subjected to differential settlement and uplift, using the analysis of Interferometry Synthetic Aperture Radar (InSAR) data. The proposed methodology is targeted towards general applicability, capable of providing assessment results for measurements over wide geographic areas and for varying structural typologies. The methodology is not limited to ground movement measurements linked to tunnelling, as is the common case. Instead it extends to the monitoring of arbitrary movement in buildings, for example, due to ground consolidation, water table changes or excavation. The methodology is designed for use alongside patrimonial building databases, from which data on individual building geometry and typology are extracted on a region or country scale. Ground movement monitoring data are used for the calculation of the building deformation, expressed in different types of deformation parameters. The combined use of this data with analytical models for settlement damage classification in building structures enables the assessment in patrimonial building structures, at a country scale. The methodology is elaborated and applied on the patrimonial inventory of Belgium for the evaluation of potential settlement and uplift damage on buildings over a period of nearly three decades. The analysis results are compared to on-site observations.

scholarly journals Failure Modes and Resistance of Perforated Steel Rib Shear Connectors under Uplift Forces

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Xiaoqing Xu ◽  
Yuqing Liu
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Analytical Models ◽  
Shear Connectors ◽  
Steel Bar ◽  
Concrete Damage ◽  
Uplift Resistance ◽  
Transverse Steel ◽  
Uplift Forces

In recent years, there is a rapid increase in the application of perforated steel rib shear connectors in steel and concrete composite structures. The connectors must not only ensure shear transfer but also sufficient uplift resistance. The shear behavior of connectors has been extensively investigated. However, studies on uplift resistance are lacking so far. Therefore, three push-out test specimens were tested to investigate the shear and tension behavior of perforated L-shaped and plain steel rib shear connectors. The failure modes of connectors were analyzed, and analytical models for the determination of uplift resistance were derived based on test results. The results showed that the ductility of perforated steel rib shear connectors under uplift force was smaller than that under shear force, and more severe concrete damage surrounding the rib and larger bending deformation of transverse steel bar was observed. The rib flange of L-shaped perforated rib has a significant contribution to the uplift resistance. It was suggested to increase the rib height of L-shaped rib to avoid the horizontal crack at the height of the rib flange. The validity of the proposed analytical models was confirmed by comparing the failure modes and capacities of specimens.

Ferroelasticity of SrCo0.8Fe0.2O3–δperovskite-related oxide with mixed ion–electron conductivity

2015 ◽  
Vol 48 (1) ◽  
pp. 179-188 ◽  
Author(s):  
I. Belenkaya ◽  
A. Matvienko ◽  
A. Nemudry
Keyword(s):  
Phase Transition ◽  
Theoretical Analysis ◽  
Mechanical Load ◽  
Electron Conductivity ◽  
Transmission Electron ◽  
Lamellar Texture ◽  
The Common ◽  
Common Nature ◽  
Means Of Transmission ◽  
Group Theoretical Analysis

A group-theoretical analysis was carried out to determine the possible orientation states of domains formed as a result of the `perovskite–brownmillerite' phase transition in SrCo0.8Fe0.2O2.5oxide with mixed ion–electron conductivity (MIEC). The results of the theoretical analysis agree with the experimental data obtained in the study of the SrCo0.8Fe0.2O2.5microstructure by means of transmission electron microscopy. Brownmillerite SrCo0.8Fe0.2O2.5(BM) has a lamellar texture composed of 90° twins 60–260 nm in size; the 〈010〉BMand 〈101〉BMdirections are linked through twinning in accordance with the predictions of the group-theoretical analysis. The presence of twins and their switching under mechanical load provide evidence that the perovskite–brownmillerite phase transition in SrCo0.8Fe0.2O2.5is ferroelastic. Comparative analysis of the phenomena observed for ferroelectrics and MIEC oxides indicates their similarity based on the common nature of ferroelectricity and ferroelasticity, and allows us to suppose that nonstoichiometric SrCo0.8Fe0.2O3−δwith compositional disorder may be considered (in terms of its microstructural features) a `relaxor ferroelastic'.

A New Holistic Approach for Subsea Pipeline Upheaval Buckling Design

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
M. Liu ◽  
C. Cross
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
A Priori ◽  
Holistic Approach ◽  
Load Factor ◽  
Fe Model ◽  
Potential Cost ◽  
Upheaval Buckling ◽  
Structural Reliability Analysis ◽  
Uplift Resistance

For a trenched and buried pipeline, the propensity to upheaval buckling (UHB) is a major design concern. Predictive UHB design is typically required at the outset to determine both trenching and backfilling requirements. Additional rockdump schedule can be established by analyzing post pipelay out of straightness (OOS) survey data incorporating appropriate safety factors based on a structural reliability analysis (SRA). The normal approach is to examine the as-laid pipeline imperfection survey statistics and data accuracy. The structural reliability analysis and load factor calculation are typically performed a priori based on the assumed initial imperfections using the universal design curve methodology. A new pseudo-energy method for UHB and OOS is proposed and discussed in this paper based on the variational principle and modal analysis. The approach takes into account the effects of varying effective axial force, trench imperfections, and vertical uplift resistance, by combining both axial friction and lateral resistance methods into a unified model. A new concept, effective uplift resistance and associated load, is also introduced to deal with nonuniform backfill cover. Adjacent imperfections and backfill profiles are considered in detail. A finite element (FE) model is developed to consist of three-noded quadratic pipe elements using abaqus Ver 6.12, and iterations of FE analyses are performed to demonstrate the tangible benefits of the approach specifically for UHB OOS design in relation to target trenching and backfilling, leading to improved reliability and potential cost saving in UHB OOS design and rockdump installation.

A UWB-2PPM Reconstruction Algorithm without a Priori Knowledge of Pilot

2014 ◽  
Vol 556-562 ◽  
pp. 3545-3548
Author(s):  
Hai Bo Yin ◽  
Jun An Yang ◽  
Jie Gong ◽  
Wei Dong Wang
Keyword(s):  
Theoretical Analysis ◽  
A Priori ◽  
Sampling Rate ◽  
Reconstruction Algorithm ◽  
A Priori Knowledge ◽  
Reconstruction Algorithms ◽  
High Sampling Rate ◽  
The Common ◽  
Transmitted Signal ◽  
Complex Channel

Compressed Sensing is very efficient in reducing the relatively high sampling rate. But when it comes to the channel estimation of uncooperative communication, the common CS reconstruction algorithms seem impractical to implement since a pilot is required, which is difficult for uncooperative communication. In this paper, we combine the sparsity transform dictionary, which is formed by a sequence of delays of the template signal, together with the idea of alternative minimization to improve the traditional CoSaMP algorithm to reconstruct under-sampled UWB-2PPM signal transmitted by unkown complex channel without a knowledge of pilot. The theoretical analysis and simulations show that the proposed algorithm is capable of reconstructing the original transmitted signal without a pilot.

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