A Discussion on How Internal Pressure is Treated in Offshore Pipeline Design

2004 ◽  
Author(s):  
Nelson Szilard Galgoul ◽  
Andre´ Luiz Lupinacci Massa ◽  
Cla´udia Albergaria Claro
Keyword(s):  
Internal Pressure ◽  
Axial Force ◽  
Research Work ◽  
Lateral Force ◽  
Poisson Effect ◽  
Cross Sectional ◽  
Starting Point ◽  
Global Buckling ◽  
Temperature And Pressure ◽  
Fixed End

The design of rigid submarine pipelines has been the object of extensive research work over the last few years, where the most relevant issues include upheaval and lateral buckling problems. Both of these problems systematically associate temperature and pressure loads, where the treatment of the first is obvious, while the latter have always been a matter of discussion. In 1974 Palmer and Baldry [1] presented a theoretical-experimental contribution, in which they have set a pattern that has been followed ever since. Another similar and well known paper was published by Sparks in 1983 [7], who only present a physical interpretation of this same theory. Most of the present day industry codes define an effective axial force, according to which, fixed end pipelines will be under compression due to internal pressure. The starting point of the discussion presented in [1] was that internal pressure produces a lateral force, which is numerically equal to the pressure times internal cross-sectional area times the pipeline curvature: q=p.Ai.d2y/dx2(1) This equation is demonstrated further ahead in this paper. Palmer and Baldry then based their arguments on the traditional equation of the pinned column buckling problem, studied by Euler [2]: EId4y/dx4+Pd2y/dx2=0(2) for which the well known solution is: P=π2EI/L2(3) and on the associated problem studied by Timoshenko [3], which adds a distributed lateral load q to the same problem: EId4y/dx4+Pd2y/dx2=q(4) Replacing q with the lateral pressure given above, they were able to have their own problem fall back onto the Euler solution: EId4y/dx4+Pd2y/dx2=p.Ai.d2y/dx2P-pAi=π2EI/L2(5) After correcting for the Poisson effect they were able to determine the new critical axial force caused by the pressure. Unfortunately, however, the arguments set forth in [1] have been misunderstood. The fact that both axial force and lateral force multiply curvature does not make them forces of the same nature. Being able to add them has solved a mathematical equation, but still hasn’t converted the lateral force to axial. The authors wish to prove that [1] presents no more than a tool, which can be used in the analysis of global buckling problems of pipelines subject to both temperature and pressure. It will be shown, however, that this pressure will not produce an axial force, as now-a-days prescribed conservatively in many pipeline codes, which is even used for stress checking.

Influences of Concentric and Eccentric Loads on Buckling of Fixed-End Supported Pultruded FRP Channel Beams

2015 ◽  
Vol 1119 ◽  
pp. 721-725 ◽  
Author(s):  
Jaksada Thumrongvut ◽  
Sittichai Seangatith
Keyword(s):  
Research Work ◽  
Geometrically Nonlinear ◽  
Cross Sectional ◽  
Modes Of Failure ◽  
Cross Sectional Dimension ◽  
Center Position ◽  
The Cross ◽  
Flexural Torsional Buckling ◽  
Fixed End ◽  
Structural Behaviors

This paper presents the results of the experimental research performed on the pultruded FRP (PFRP) channel beams subjected to transversely concentric and eccentric loads. The objectives of the research work are to investigate their structural behaviors and to determine the critical buckling moments and modes of failure of the beams with various span-to-depth ratios and eccentricities. Pultruded beams are fixed-end supported at both ends for major and minor-axis flexure. The beam specimens have the cross-sectional dimension of 102×29×6 mm with span-to-depth ratios, ranging from 20 to 40. A total of 40 mono-symmetric section tests were performed. The effects of vertical load position through the cross-section were studied. Also, shear center position with concentric load and three different eccentricities were investigated ranging from 0 to-3e. The specimens were tested to final buckling. Based upon the results of this study, it is found that the load versus mid-span vertical deflection relationships of the beams are linear up to the failure. On the contrary, the load versus mid-span lateral deflection relationships are geometrically nonlinear. The general mode of failure is the flexural-torsional buckling. The eccentrically loaded specimens are failed at buckling loads lower than their concentric counterparts. Overall, the critical buckling moment decreases as the magnitude of eccentricity increases. Additionally, it is noticed thatL/dratio increases, the critical buckling moment is decreased.

Tube Bending Under Axial Force and Internal Pressure

2005 ◽  
Vol 128 (2) ◽  
pp. 598-605 ◽  
Author(s):  
Jyhwen Wang ◽  
Rohit Agarwal
Keyword(s):  
Internal Pressure ◽  
Axial Force ◽  
Shape Control ◽  
Analytical Models ◽  
Thickness Variation ◽  
Tube Bending ◽  
Cross Sectional ◽  
Thickness Change ◽  
Model Predictions ◽  
Good Agreement

Tube bending is a widely used manufacturing process in the aerospace, automotive, and various other industries. During tube bending, considerable in-plane distortion and thickness variation occurs. Additional loadings such as axial force and internal pressure can be used to achieve better shape control. Based on plasticity theories, analytical models are developed to predict cross-sectional distortion and thickness change of tubes under various loading conditions. The model predictions are in good agreement with finite element simulations and published experimental results. The models can be used to evaluate tooling and process design in tube bending.

Impacto de la comunicación de la responsabilidad social universitaria en la selección de universidad y efecto mediador de la reputación

2020 ◽  
Author(s):  
Lucy Erazo-Coronado ◽  
Sergio Llano-Arristizábal ◽  
Miguel Garcés-Prettel ◽  
Ana-María Erazo-Coronado
Keyword(s):  
Social Responsibility ◽  
Professional Training ◽  
Research Work ◽  
Community Support ◽  
Human Beings ◽  
Cross Sectional ◽  
Public And Private ◽  
University Selection ◽  
Cross Sectional Design ◽  
Institutional Websites

The emerging concept of university social responsibility (USR) consists in the fulfillment of the mission of the university in terms of ethical standards, community support, respect for human beings, and respect for the environment. Thus, universities must not only provide professional training but also instill ethical principles in students to allow them to behave as good citizens and help solve community problems. On the other hand, competition for students requires efficient management of university reputation and communication with their stakeholders, to demonstrate the accomplishment of the university’s mission and attract potential students. The objective of this paper is thus to explain the causal relationship between communication about university social responsibility (USR) activities through institutional websites and university selection, as well as the role of reputation. Research work was carried out based on an explanatory cross-sectional design, with a sample of 356 subjects from a population of 11th-grade students from public and private schools in the City of Barranquilla (Colombia). The results revealed that USR communication through institutional websites has a significant influence on university selection, not only directly but also indirectly, through reputation as a mediating variable. These findings contribute at a theoretical level by providing empirical evidence to understand and explain the analyzed topic. Furthermore, the results provide useful information to evaluate USR disclosure and implement strategies to make progress on USR issues. Resumen El naciente concepto de responsabilidad social universitaria (RSU) consiste en el cumplimiento de la misión de la universidad dentro de unos estándares éticos, de apoyo a la comunidad, respeto al ser humano y al medio ambiente. Así, pues, la universidad no sólo debe impartir formación profesional, sino inculcar a sus estudiantes principios éticos que les permitan comportarse como buenos ciudadanos y contribuir a la solución de los problemas de la comunidad. Por otra parte, la competencia entre universidades exige una gestión eficiente de su reputación y de la comunicación con sus distintos stakeholders, para demostrar a la sociedad el cumplimiento de su misión social, y para atraer estudiantes potenciales hacia la institución. Por lo tanto, este artículo tiene como objetivo explicar la relación de causalidad entre la comunicación de las prácticas de RSU en los sitios web institucionales y la selección de universidad, y el papel mediador de la reputación en esta relación. Para lograrlo, se llevó a cabo una investigación cuantitativa de nivel explicativo experimental y diseño transversal, con una muestra conformada por 356 sujetos, de una población de estudiantes de grado 11º de colegios públicos y privados de la ciudad de Barranquilla (Colombia). Los resultados revelan que la comunicación de las prácticas de RSU en los sitios web institucionales ejerce una influencia significativa directa en la intención de selección de universidad, e indirecta, a través de la reputación como variable mediadora. La evidencia empírica aportada representa un avance teórico en la comprensión y explicación del fenómeno estudiado, e igualmente servirá para que las universidades evalúen si están comunicando adecuadamente su responsabilidad social y adopten estrategias para avanzar en este aspecto.

scholarly journals Examining Australian public perceptions and behaviors towards a future COVID-19 vaccine

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Holly Seale ◽  
Anita E. Heywood ◽  
Julie Leask ◽  
Meru Sheel ◽  
David N. Durrheim ◽  
...  
Keyword(s):  
Online Survey ◽  
Private Health Insurance ◽  
Public Perceptions ◽  
Multivariable Logistic Regression Model ◽  
Careful Planning ◽  
Cross Sectional ◽  
The Public ◽  
Individual Perceptions ◽  
Starting Point ◽  
Early Indication

Abstract Background As immunisation program launches have previously demonstrated, it is essential that careful planning occurs now to ensure the readiness of the public for a COVID-19 vaccine. As part of that process, this study aimed to understand the public perceptions regarding a future COVID-19 vaccine in Australia. Methods A national cross-sectional online survey of 1420 Australian adults (18 years and older) was undertaken between 18 and 24 March 2020. The statistical analysis of the data included univariate and multivariable logistic regression model analysis. Results Respondents generally held positive views towards vaccination. Eighty percent (n = 1143) agreed with the statement that getting myself vaccinated for COVID-19 would be a good way to protect myself against infection. Females (n = 614, 83%) were more likely to agree with the statement than males (n = 529, 78%) (aOR = 1.4 (95% CI: 1.1–1.8); P = 0.03), while 91% of those aged 70 years and above agreed compared to 76% of 18–29-year-olds (aOR = 2.3 (95% CI:1.2–4.1); P = 0.008). Agreement was also higher for those with a self-reported chronic disease (aOR = 1.4 (95% CI: 1.1–2.0); P = 0.04) and among those who held private health insurance (aOR = 1.7 (95% CI: 1.3–2.3); P < 0.001). Beyond individual perceptions, 78% stated that their decision to vaccinate would be supported by family and friends. Conclusion This study presents an early indication of public perceptions towards a future COVID-19 vaccine and represents a starting point for mapping vaccine perceptions. To support an effective launch of these new vaccines, governments need to use this time to understand the communities concerns and to identify the strategies that will support engagement.

scholarly journals A Bibliometric Analysis of the Global Trend of Using Alginate, Gelatine, and Hydroxyapatite for Bone Tissue Regeneration Applications

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 647
Author(s):  
Mohamed Saiful Firdaus Hussin ◽  
Aludin Mohd Serah ◽  
Khairul Azri Azlan ◽  
Hasan Zuhudi Abdullah ◽  
Maizlinda Izwana Idris ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Bibliometric Analysis ◽  
Research Work ◽  
The United States ◽  
Research Area ◽  
Bone Tissue Regeneration ◽  
Future Research ◽  
Starting Point

Collecting information from previous investigations and expressing it in a scientometrics study can be a priceless guide to getting a complete overview of a specific research area. The aim of this study is to explore the interrelated connection between alginate, gelatine, and hydroxyapatite within the scope of bone tissue and scaffold. A review of traditional literature with data mining procedures using bibliometric analyses was considered to identify the evolution of the selected research area between 2009 and 2019. Bibliometric methods and knowledge visualization technologies were implemented to investigate diverse publications based on the following indicators: year of publication, document type, language, country, institution, author, journal, keyword, and number of citations. An analysis using a bibliometric study found that 7446 papers were located with the keywords “bone tissue” and “scaffold”, and 1767 (alginate), 185 (gelatine), 5658 (hydroxyapatite) papers with those specific sub keywords. The number of publications that relate to “tissue engineering” and bone more than doubled between 2009 (1352) and 2019 (2839). China, the United States and India are the most productive countries, while Sichuan University and the Chinese Academy of Science from China are the most important institutions related to bone tissue scaffold. Materials Science and Engineering C is the most productive journal, followed by the Journal of Biomedical Materials Research Part A. This paper is a starting point, providing the first bibliometric analysis study of bone tissue and scaffold considering alginate, gelatine and hydroxyapatite. A bibliometric analysis would greatly assist in giving a scientific insight to support desired future research work, not only associated with bone tissue engineering applications. It is expected that the analysis of alginate, gelatine and hydroxyapatite in terms of 3D bioprinting, clinical outcomes, scaffold architecture, and the regenerative medicine approach will enhance the research into bone tissue engineering in the near future. Continued studies into these research fields are highly recommended.

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

The emergence of entrepreneurial team as a research field – way forward

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Willy Das ◽  
Satyasiba Das ◽  
Manojit Chattopadhyay
Keyword(s):  
Research Agenda ◽  
Research Field ◽  
Academic Disciplines ◽  
Future Research ◽  
Cross Sectional ◽  
Content Type ◽  
Future Research Agenda ◽  
Starting Point ◽  
Entrepreneurial Team ◽  
Research Stream

PurposeThe purpose of this paper is to review and critique the existing literature on entrepreneurial teams (ET) by taking a multi-disciplinary viewpoint and provide a future research agenda based on the identified themes and trends.Design/methodology/approachA systematic literature review (SLR) was undertaken using “business source complete”. Further scrutiny and application of exclusion criteria led to a final sample consisting of 139 papers from 27 different journals belonging to not just entrepreneurship and strategic management but also other disciplines like OB, finance, sociology, psychology, etc. Using qualitative thematic analysis, the authors identified 11 major themes.FindingsThe paper reviews both the eleven themes and the linkages between the themes. Thereby identifying areas that have been understudied and those that have received comparatively more attention. The review revealed that the research stream possesses certain conceptual and methodological concerns apart from its cross-sectional and primarily bivariate nature. Five such main concerns have been identified and discussed in detail. Other elements of the resulting research agenda include calls for more clinical process-oriented research, further attention to context, shifting the level of analysis, and a need to integrate across disciplines.Originality/valueThis paper incorporates a broad insight of ET across academic disciplines to show how future contributions could benefit by incorporating research from other fields. In doing so, provides a starting point for more nuanced discussions around the interrelationships between the different conversations that are taking place in the ET literature.

Preliminary design of precast, segmental box-girder bridges using optimization

1979 ◽  
Vol 6 (1) ◽  
pp. 120-128
Author(s):  
Craig J. Miller ◽  
Juarez Accioly
Keyword(s):  
Minimum Cost ◽  
Preliminary Design ◽  
Box Girder Bridges ◽  
Cross Sectional ◽  
Box Girder ◽  
Prestressing Steel ◽  
Girder Bridges ◽  
Starting Point ◽  
Final Design ◽  
The Cost

Precast, prestressed segmental box-girder bridges are now accepted as an economical alternative for spans over 150 ft (46 m). Decisions about cross-sectional dimensions made during preliminary design can have a substantial influence on the final cost of the bridge. To help the designer obtain an economical starting point for a final design, a program was written to determine section dimensions and midspan and pier prestressing steel areas to give minimum cost. Since a preliminary design is obtained, the analysis techniques and design criteria have been simplified to reduce computation. The design produced by the program will satisfy AASHTO specification requirements and the recommendations of the PCI Bridge Committee. The optimization algorithm used is the generalized reduced gradient technique. To demonstrate the program capabilities, three example problems are discussed. The results indicate that optimum span-depth ratios are approximately 24 for the cost ratios used. The cost of the optimum design does not seem to be too sensitive to the ratio of concrete cost to prestressing steel cost.

scholarly journals MRI Study on Tibial Nerve of the Ankle Canal and Its Branches: A method of multiplanar reconstruction with 3D-FIESTA-C sequences

2020 ◽  
Author(s):  
Yan Zhang ◽  
Xucheng He ◽  
Juan Li ◽  
Ju Ye ◽  
Wenjuan Han ◽  
...  
Keyword(s):  
Tibial Nerve ◽  
Three Dimensional ◽  
The Body ◽  
Multiplanar Reconstruction ◽  
Medial Malleolus ◽  
Cross Sectional ◽  
Medial Plantar Nerve ◽  
Lateral Plantar Nerve ◽  
Good Imaging ◽  
Starting Point

Abstract Background The display of tibial nerve and its branches in the ankle canal is helpful for the diagnosis of local lesions and compression, and also for clinical observation and surgical planning.The aim of this study was to investigate the feasibility of three-dimensional dual-excitation balanced steady-state free precession sequence (3D-FIESTA-C) multiplanar reconstruction (MPR) display of tibial nerve and its branches of the ankle canal. Methods The subjects were 20 healthy volunteers (40 ankles), aged 22–50, with no history of ankle joint desease. 3D-FIESTA-C sequence was used in the 3.0t magnetic resonance equipment for imaging. During the scanning, each foot was at a 90-degree angle to the tibia.The tibial nerve of the ankle canal and its branches were displayed and measured at the same level through multiplanar reconstruction. Results Most of the tibial nerve bifurcation points were located in the ankle canal (57.5%), few (42.5%) were located at the proximal end of the ankle canal, and none was found away from the distal end. The bifurcation between the medial plantar nerve and the lateral plantar nerve is on the line between the tip of the medial malleolus and the calcaneus, and it’s angle is between 6° and 35°.The average cross-sectional diameter of the medial plantar nerve is about mm, and the lateral plantar nerve about mm. In MPR images, the display rates of both the medial calcaneal nerve and the subcalcaneal nerve were 100%, and the starting point of the subcalcaneal nerve was always at the distal end of the starting point of the medial calcaneal nerve. In 55% of cases, there were more than 2 medial calcaneal nerve innervations. Conclusion The 3D-FIESTA-C MPR can display the morphological features and positions of tibial nerve and its branches and the bifurcation point’s projection position on the body surface can be marked. This method not only benefited the imaging diagnosis of tibial nerve and branch-related lesions of the ankle canal, but also provided a good imaging basis to plan the clinical operation of the ankle canal and avoid surgical injury.

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