Jack-Up Site Assessment: The Voyage to an ISO

2011 ◽  
Author(s):  
Mike J. R. Hoyle ◽  
John J. Stiff ◽  
Rupert J. Hunt
Keyword(s):  
Offshore Structures ◽  
Site Assessment ◽  
Detailed Review ◽  
Technical Developments ◽  
Ocean Environment ◽  
The Many ◽  
Analytical Tools ◽  
Jack Up ◽  
Safe Working

As a mobile offshore unit, a jack-up can float, self-elevate and then impose proofing loads on the seabed to establish a safe working envelope for subsequent drilling or construction activities. Jack-up site assessment has seen significant advances over the 50 or more years that jack-ups have been deployed offshore. The advances have occurred as a result of both the improvements that have been seen in the analytical tools and also as a result of the many significant strides in our understanding of the physics of the jack-up and the ocean environment. Jack-ups, due to their semi-compliant nature, pose particularly difficult challenges to the designer and operator — more so than most offshore structures. This requires cutting edge technologies to assure that practical solutions can be reached without either too much conservatism or too little safety. These advances have often occurred, or been encouraged, as a result of the engagement of the operators hiring the jack-ups and their technical overseers such as Jan Vugts. Jan was instrumental in initiating the Shell study into jack-up site assessment that resulted in a follow-up JIP which developed the SNAME Recommend Practice. Since then ISO 19905-1 has been under development and Jan has provided both encouragement and also very detailed review comments. This paper charts the voyage from the early days of jack-up site assessment through to the development of the ISO and highlights some of the key technical developments.

scholarly journals The Impact of Dental Implant Length on Failure Rates: A Systematic Review and Meta-Analysis

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3972
Author(s):  
Maha Abdel-Halim ◽  
Dalia Issa ◽  
Bruno Ramos Chrcanovic
Keyword(s):  
Treatment Plan ◽  
Meta Analysis ◽  
Implant Failure ◽  
Failure Rates ◽  
Manual Search ◽  
Short Implants ◽  
The Many ◽  
The Impact ◽  
Implant Length

The present review aimed to evaluate the impact of implant length on failure rates between short (<10 mm) and long (≥10 mm) dental implants. An electronic search was undertaken in three databases, as well as a manual search of journals. Implant failure was the outcome evaluated. Meta-analysis was performed in addition to a meta-regression in order to verify how the risk ratio (RR) was associated with the follow-up time. The review included 353 publications. Altogether, there were 25,490 short and 159,435 long implants. Pairwise meta-analysis showed that short implants had a higher failure risk than long implants (RR 2.437, p < 0.001). There was a decrease in the probability of implant failure with longer implants when implants of different length groups were compared. A sensitivity analysis, which plotted together only studies with follow-up times of 7 years or less, resulted in an estimated increase of 0.6 in RR for every additional month of follow-up. In conclusion, short implants showed a 2.5 times higher risk of failure than long implants. Implant failure is multifactorial, and the implant length is only one of the many factors contributing to the loss of an implant. A good treatment plan and the patient’s general health should be taken into account when planning for an implant treatment.

Numerical Study of the Combined Loading Envelope of a Skirted Spudcan Foundation

2014 ◽  
Author(s):  
Ning Cheng ◽  
Mark J. Cassidy ◽  
Yinghui Tian
Keyword(s):  
Clay Soil ◽  
Numerical Study ◽  
Failure Mechanisms ◽  
Small Strain ◽  
Offshore Structures ◽  
Combined Loading ◽  
Finite Element Analyses ◽  
Failure Envelope ◽  
Foundation Type ◽  
Jack Up

Foundations for offshore structures, such as mobile jack-up units, are subjected to large horizontal (H) and moment (M) loads in addition to changing vertical (V) loads. The use of a combined vertical, horizontal and moment (V-H-M) loading envelope to define foundation capacities has become increasingly applied in recent years. However, there is no study on the skirted spudcan, a new alternative foundation type to the conventional spudcan footing for jack-ups. In this study, the combined V-H-M yield envelope of a skirted spudcan foundation in clay soil is investigated with small strain finite element analyses using 3D modeling. The footing’s uniaxial bearing capacities and failure mechanisms are described. The failure envelope for the combined V-H-M loadings is presented. A comparison of the bearing capacities between the spudcan and skirted spudcan of various dimensions is also presented.

scholarly journals A “Scientist” on the Radio: Understanding the Framing of STEM to the Public

2015 ◽  
Vol 1 (2) ◽  
pp. 125-141
Author(s):  
G. Michael Bowen ◽  
Richard Zurawski ◽  
Anthony Bartley
Keyword(s):  
Information Management ◽  
News Media ◽  
Management Practices ◽  
Radio Station ◽  
The Public ◽  
Research Fields ◽  
Factual Content ◽  
The Many ◽  
Radio Broadcast

News media presentations of STEM (and particularly science) in various formats have been critiqued for the many ways by which they misrepresent both the facts of the discipline and the practices of the discipline and the researchers in them. Another issue is that the material is presented in a format – basically a one-way transmission – with usually little opportunity for questions by the recipients (i.e., readers, listeners, viewers, etc.) to be addressed when they don’t understand something. One news media format which might allow this dialogic activity is the radio call-in show format which is structured so that the public can ask questions of a “scientist” with the opportunity for follow-up questions to address what are discontinuities in the listener’s understanding. In this paper we document the processes by which listener interests ultimately end up discussed in the radio broadcast and what influences the “science” that is presented on-air. Our analysis reports the ways in which the STEM topics and content are mediated by radio station personnel, often times distorting the factual content available to the public and misrepresenting the practices of the research fields, as they engage in information management practices which are typical of opinion-driven shows (such as those on the topics of politics or sports) which are designed to create controversy and drama to increase ratings.

scholarly journals Considering the importance of metaphors for marine conservation

2018 ◽  
Author(s):  
Alasdair Neilson
Keyword(s):  
Scientific Evidence ◽  
Environmental Issues ◽  
Marine Conservation ◽  
Ocean Environment ◽  
The Many ◽  
The Way ◽  
Culturally Embedded

This paper seeks to highlight the importance of metaphors for marine conservation and policy. It argues that themanner in which the oceans are perceived, often as an alien landscape, can limit the way language is utilised inmarine conservation efforts. This limitation can produce unhelpful environmental metaphors that, instead ofacting as catalysts for action, produce negative and reactionary responses. It illustrates this point through theexample of what has become known as the ‘Great Pacific Garbage Patch.’ It postulates that if there is a disconnectbetween the many complex environmental issues facing the world's oceans and the way they are perceived, thenmore focus should be placed on developing pre-determined culturally embedded metaphors, which can conjurerelatable imagery, but that are also rooted in scientific evidence. It recommends that, in an extension to existingpublic perception research (PPR) on how different communities value the ocean environment, there is room forshared metaphors of the oceanic environment to be developed that can help raise awareness within a particularcultural setting.

scholarly journals THE DYNAMIC RESPONSE OF OFFSHORE STRUCTURES TO TIME-DEPENDENT FORCES

1964 ◽  
Vol 1 (9) ◽  
pp. 29
Author(s):  
William S. Gaither ◽  
David P. Billington
Keyword(s):  
Degrees Of Freedom ◽  
Wind Waves ◽  
Offshore Structures ◽  
Time Dependent ◽  
Wave Forces ◽  
Ocean Bottom ◽  
Single Wave ◽  
Single Degree Of Freedom ◽  
The Many ◽  
Floating Objects

This paper is addressed to the problem of structural behavior in an offshore environment, and the application of a more rigorous analysis for time-dependent forces than is currently used. Design of pile supported structures subjected to wave forces has, in the past, been treated in two parts; (1) a static analysis based on the loading of a single wave, and (2) a dynamic analysis which sought to determine the resonant frequency by assuming that the structure could be approximated as a single-degree-of-freedom system. (Ref. 4 and 6) The behavior of these structures would be better understood if the dynamic nature of the loading and the many degrees of freedom of the system were included. A structure which is built in the open ocean is subjected to periodic forces due to wind, waves, floating objects, and due occasionally to machinery mounted on the structure. To resist motion, the structure relies on the stiffness of the elements from which it is built and the restraints of the ocean bottom into which the supporting legs are driven.

scholarly journals New Investigations for Offshore and Onshore structures

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Levent Yilmaz
Keyword(s):  
State Of The Art ◽  
Offshore Structures ◽  
History Of ◽  
Jack Up

In this research the investigated parameters are given as below: History of offshore and onshore construction…Onshore structures…StorageTanks Breakwaters……Estacada…Offshore structures…Stationary fixed platforms (steel, concrete, combined, arctic)…Floating (Jack-up, semi-submersibles, TLP,…)…Pipe lineThis issues are given as State-of-the-art and written new examined innovative researches.

Analysis and Design of Offshore Pile Foundation

2014 ◽  
Vol 891-892 ◽  
pp. 17-23 ◽  
Author(s):  
Sudip Basack
Keyword(s):  
Pile Foundation ◽  
Complex Loading ◽  
Offshore Structures ◽  
Laboratory Model ◽  
Element Analysis ◽  
Analysis And Design ◽  
Theoretical Investigations ◽  
Experimental Laboratory ◽  
Combined Action ◽  
Ocean Environment

The ocean environment necessitates the pile foundation supporting the offshore structures to be designed against cyclic load, moments and torques initiated by a combined action of waves, wind, tides, currents, etc. Such a complex loading condition induces progressive degradation in the pile-soil interactive performance introducing significant reduction in bearing capacity with increased settlement and displacements. The Author has carried out extensive experimental (laboratory model tests) and theoretical investigations (boundary element analysis) to study the salient features of this degradation and developed a design methodology for offshore pile foundation. The works conducted and the major conclusions drawn are highlighted in this paper.

Microfinance RCTs in Development

2020 ◽  
pp. 186-226
Author(s):  
Florent Bédécarrats ◽  
Isabelle Guérin ◽  
François Roubaud
Keyword(s):  
Political Economy ◽  
External Validity ◽  
Data Entry ◽  
Special Issue ◽  
Collection Data ◽  
The Many ◽  
Dissemination Of Results ◽  
Analytical Tools ◽  
Internal And External Validity ◽  
Political Success

Microcredit has long stood as a flagship topic for RCTs in development, starting with the publication of a special issue in a leading economics journal on six RCTs conducted in different world regions. This special issue was hailed as the first rigorous and conceivably definitive study on the impacts of microcredit. However, a detailed exploration of the implementation of these six RCTs reveals many limitations with respect to internal and external validity, ethics, and interpretation. This chapter uses analytical tools from statistics, political economy, and development anthropology to discuss the extent to which the entire RCT chain strays from the ideal RCT principles (from sampling, data collection, data entry and recoding, estimates and interpretation to publication and dissemination of results). It also raises questions about the disparity between the academic and political success of this special issue and the many inconsistencies of method.

“I'm Here for You”

2016 ◽  
pp. 55-75 ◽  
Author(s):  
Kelly R. Elander
Keyword(s):  
Online Learning ◽  
Video Clips ◽  
Instructor Presence ◽  
Historical Role ◽  
The Many

The author examines instructor presence by considering its historical role, the many important tasks that instruction presence accomplishes, and many ways instructional presence can be shown in online learning. Instructor presence has historically fulfilled four key functions: guidance, socialization, motivation, and coordination. Tasks that instructor presence can help with include welcoming and orienting learners, providing grades and explanations for grades, communicating course and instructor expectations and feedback on learner work, offering follow-up questions and comments, and moderating discussions. Seven techniques suggested to provide a sense of instructor presence include scheduling predetermined, regular appearances online, providing quick responses to comments and assignments, making occasional instructor posts throughout course discussions, offering periodic, brief, personal comments, providing special periods of instructor access, simulating presence by means of prerecorded audio or video clips and using instructor representatives.

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