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Submarine pipeline was widely used to transport oil and gas in offshore petroleum exploitation. In practice, deep-water pipeline experiences several times of maintenance every year. This periodic o...

Deep-sea pipelines exhibit lateral global buckling under high temperature and pressure differences. Numerical simulations are an effective and easy way to obtain the deformation and stress distribution of a post-buckling pipeline with a low cost. A relatively accurate and convenient simulation model using the explicit dynamic method was developed based on ABAQUS software to analyse pipeline lateral global buckling. In pipeline global buckling analysis, the dynamic variation of soil resistance as the pipeline moves laterally, the optimized computational length and the use of smooth initial imperfection profiles influence the accuracy of the simulation results. These three key factors were discussed here, and calculation methods were proposed. A CEL simulation model with improved boundary conditions that reduce the influence of wave reflection with a low calculation time cost was built to calculate the variation dynamics of soil resistance throughout the buckling process. Different computational lengths for pipelines with different parameters were simulated, and a fitting function to obtain an optimized computational length was proposed. A method to build the profiles of a pipeline with smooth imperfections was developed. Based on these analyses of the three impact factors, a relatively accurate and convenient simulation model for pipeline global lateral buckling analysis was established. Finally, an engineering case was evaluated to show the application of the simulation model and to test the reliability of this model.

Commercialization and corporatization (C&C) in American higher education since the 1980s have gradually marginalized shared governance in various areas. This chapter is a case study of an American public university, based on empirical studies through in-depth surveys, observations, and base data collection. It addresses the issue of academic commercialization and corporatization and their impact on shared governance, faculty morale, and faculty strain in their research, teaching, and service. After defining the key concepts, explaining the methodology and discussing the data, this chapter examines the roles of commercialization and corporatization in decreasing shared governance and lowering faculty morale in academic research, teaching, and service. The chapter concludes that, with the erosion of academic freedom and faculty power, academic commercialization and corporatization have created dissatisfaction among faculty members who lack pride in their profession and distrust administrators.

Pipeline walking is a global axial movement caused by the asymmetric distribution of axial force along the pipeline during the repetitive operational loading cycle. The pipeline walking rate, increasing with the loading cycles, may lead to high stress thereby the failure of connectors at PLETs or PLEMs. Current research studies and design guidelines focused on free-end pipelines and neglected changes in the pipeline walking rate and axial resistance with effects of pipeline end structures. However, in practice, several pipelines are adjacent to PLETs or PLEMs, which potentially affect the pipeline walking and expansion behaviour thereby walking rate and axial displacement. This study analyses the walking phenomenon considering the effects of mobilisation of the resistance at the pipeline end structures and develops new analytical solutions for the present problem, in terms of different walking mechanism, maximum axial resistance Pmax, and positions of pipeline end structures. The analytical solutions are validated through numerical simulation results. The case study results indicate the axial resistance generated by PLETs/PLEMs can effectively mitigate pipeline walking rate compared with free-end pipeline walking. In particular, the influence of PLETs/PLEMs is investigated, highlighting the sensitivity of the pipeline walking to the end boundary conditions covering different design scenarios.

Pipelines are widely used for transporting oil resources in offshore oil exploitation. As burying an entire deep-water pipeline is not possible owing to the large water depth, an on-bottom pipeline inevitably exhibits lateral global buckling deformation under high temperature and pressure in practice. Triggering several controllable mitigatory global buckling deformations by installing sleepers under pipelines is a more effective alternative to prevent cross-sectional failure caused by excessive buckling. While sleepers may trigger vertical global buckling and this risk must be verified before they are installed in practice. This study analysed the feature of lifting deformation for a pipeline laid on a sleeper. Nine influential factors of the variation in the lifting displacement were analysed. Based on the nonlinear relationship between lifting displacement and temperature difference, three key points and four relevant key parameters for describing the lifting displacement curve were proposed and calculated for the conditions of a pipeline with different combinations of influential factors. A back propagation neural network was trained to model the relationship between the locations of the three key points and the values of the nine influential factors. The error analysis indicated that the trained network can effectively predict the vertical lifting deformation and is suitable for a pipeline that experiences no lifting deformation. Based on the feature points predicted by the trained network, the approximate profile of vertical lifting displacement during the heating process can be described, and the assessment of whether the lifting displacement with the loading conditions in practice is allowable can be conducted.

With the development of submarine oil and gas resources, research on global pipeline buckling caused by high temperature and pressure in the process of oil and gas transport is becoming an important issue. Owing to human factors or to uneven seabed conditions, local bends are produced in the process of pipeline manufacturing and laying. Those bends are called geometric initial imperfections whose deformation forms can be divided into a single arch symmetric deformation and a double arch antisymmetric deformation. In this paper, the energy method is introduced to calculate the analytical solution of pipeline lateral buckling with a single arch initial imperfection, and the cause of snap buckling phenomenon is discussed. A FEA model is established, and the difference between the analytical solution and numerical solution is also presented.

Submarine pipelines are the primary component of an offshore oil transportation system. Under operating conditions, a pipeline is subjected to high temperatures and pressures to improve oil mobility. As a result, additional stress accumulates in pipeline sections, which causes global buckling. For an exposed deep-water pipeline, lateral buckling is the major form of this global buckling. Large lateral displacement causes a very high bending moment which may lead to a local buckling failure in the pipe cross-section. This paper proposes a lateral global buckling failure envelope for deep-water HT/HP pipelines using a numerical simulation analysis. It analyzes the factors influencing the envelope, including the thickness t, diameter D, soil resistance coefficient μ, calculating length Lf, imperfection length L and imperfection amplitude V. Equations to calculate the failure envelope are established to make future post-buckling pipeline failure assessment more convenient. The results show that (1) the limit pressure difference pmax (the failure pressure difference for a post-buckling pipeline when it suffers no difference in temperature) is usually below the burst pressure difference pb (which is the largest pressure difference a pipeline can bear and is determined from the strength and sectional dimensions of the pipeline) and is approximately 0.62–0.75 times the value of pb and (2) thickness t has little influence on the normalized envelopes, but affects pmax. The diameter D, soil resistance coefficient μ, and calculating length Lf influence the maximum failure temperature difference Tmax (the failure temperature difference for a pipeline suffering no pressure difference). The diameter D also significantly affects the form of the normalized envelope.

With the increase in pipeline operating depth, research on pipeline global buckling during the process of oil and gas transport is drawing considerable attention. Numerical simulation is an important method that is used to analyze pipeline buckling, which is immediately caused by the combined action of high temperature and high pressure. Two important problems must be solved before simulating submarine pipeline global buckling. Because the finite-element (FE) model length greatly affects analysis of the buckling results, finding a reasonable model length is the first problem in finite-element analysis (FEA). The second is how to trigger global buckling in the pipeline because the ideal pipeline would not buckle in FEA. Previous studies only state that geometric initial imperfection and interference force could trigger pipeline global buckling. Therefore, simulating pipeline global buckling in FEA becomes a problem. In this paper, an effective method for calculating the reasonable model length (als...

Given the fact that the new private entrepreneurs (NPEs) are playing an increasingly important role in Chinese politics and economy, this article maps the historical evolution of the NPEs through analyzing five main private business groups, including small individual businessmen, price speculators, land speculators, enterprise investors and high-tech investors. The article also examines six major ways that the NPEs have sought to protect their private property and improve their moral reputation, ranging from obtaining the Communist Party membership, congressional seat and an official position within a government branch, to relying on the law, participating in the local election process, and contributing to charitable causes. In so doing, they have increased their influence in the Chinese political, social, and economic spheres.