Nonlinear vibration analysis of pipeline considering the effects of soft nonlinear clamp

Soft nonlinear support is a major engineering project,but there are few relevant studies.In this paper,a dynamic pipeline model with soft nonlinear supports at both ends is established.By considering the influence of the Coriolis force and centrifugal force,the dynamical coupling equation of fluid-structure interaction is derived with extended Hamilton’s principle.Then,the approximate analytical solutions are sought via the harmonic balance method.The amplitude-frequency response curves show that different effects can be determined by approximate analysis.It is demonstrated that the increase in the fluid velocity can increase the amplitude of the pipeline system.The frequency range of unstable response increases when the fluid pressure raises.The combination of the soft nonlinear clamp and the large geometrical deformation of the pipeline affects the nonlinear vibration characteristic of the system,and the external excitation force and damping have significant effects on the stability.

Assessment of pipeline stability in the Gulf of Mexico during hurricanes using dynamic analysis

Pipelines are the critical link between major offshore oil and gas developments and the mainland. Any inadequate on-bottom stability design could result in disruption and failure, having a devastating impact on the economy and environment. Predicting the stability behavior of offshore pipelines in hurricanes is therefore vital to the assessment of both new design and existing assets. The Gulf of Mexico has a very dense network of pipeline systems constructed on the seabed. During the last two decades, the Gulf of Mexico has experienced a series of strong hurricanes, which have destroyed, disrupted and destabilized many pipelines. This paper first reviews some of these engineering cases. Following that, three case studies are retrospectively simulated using an in-house developed program. The study utilizes the offshore pipeline and hurricane details to conduct a Dynamic Lateral Stability analysis, with the results providing evidence as to the accuracy of the modeling techniques developed.

A Comprehensive Review on RNA-seq Data Analysis

RNA-sequencing(RNA-seq),based on next-generation sequencing technologies,has rapidly become a standard and popular technology for transcriptome analysis.However,serious challenges still exist in analyzing and interpreting the RNA-seq data.With the development of high-throughput sequencing technology,the sequencing depth of RNA-seq data increases explosively.The intricate biological process of transcriptome is more complicated and diversified beyond our imagination.Moreover,most of the remaining organisms still have no available reference genome or have only incomplete genome annotations.Therefore,a large number of bioinformatics methods for various transcriptomics studies are proposed to effectively settle these challenges.This review comprehensively summarizes the various studies in RNA-seq data analysis and their corresponding analysis methods,including genome annotation,quality control and pre-processing of reads,read alignment,transcriptome assembly,gene and isoform expression quantification,differential expression analysis,data visualization and other analyses.

Asset Integrity Management in Mitigating Oil and Gas Pipeline Vandalism in the Niger Delta Region—Deep Burial Solution

Pipelines, as means of transportation of water and hydrocarbon have been considered “effective, safe and reliable”. Over the years, pipeline failures in Niger Delta region of Nigeria have resulted in loss of lives, water pollution, soil contamination, air pollution, destruction of infrastructures and aquatic lives, and other losses. The study area, Niger Delta region is located on Latitude 4°50' 00"N, longitude 6°00'00"E and comprised of nine coastal states of Nigeria (about 70,000 km2). Failure data were collected using: Questionnaires administered to experienced pipeline engineers in the International oil and gas companies (IOCs), Personnel interviews, and reports from the Department of Petroleum Resources, Nigerian National Petroleum Corporation (NNPC). This study assessed the strategies employed by four IOCs to mitigate pipeline failures in the process of asset integrity management. Design and construction methods detailing pipelines laying to infiltration discouraging-depth were studied. The results obtained showed that vandalism is presently the major cause of pipeline failures. Deep burial solution was therefore explored as a vandalism mitigation approach and its cost of implementation for a typical Φ20"× 15 km trunkline in the region showed 9.627% (≈809.3 million Naira) rise compared to the normal burial option, and this difference accrued mainly from equipment and personnel cost. This is a paltry sum compared to the huge losses due to vandalism. Finally, this study posits that the available regulatory framework is now inadequate for pipeline design, construction, and operations due to this challenge and requires urgent amendment in favour of deep burial option.

Detecting differential expression from RNA-seq data with expression measurement uncertainty

High-throughput RNA sequencing （RNA-seq） has emerged as a revolutionary and powerful technology for expression profiling. Most proposed methods for detect- ing differentially expressed （DE） genes from RNA-seq are based on statistics that compare normalized read counts be- tween conditions. However, there are few methods consider- ing the expression measurement uncertainty into DE detec- tion. Moreover, most methods are only capable of detecting DE genes, and few methods are available for detecting DE isoforms. In this paper, a Bayesian framework （BDSeq） is proposed to detect DE genes and isoforms with consideration of expression measurement uncertainty. This expression mea- surement uncertainty provides useful information which can help to improve the performance of DE detection. Three real RAN-seq data sets are used to evaluate the performance of BDSeq and results show that the inclusion of expression mea- surement uncertainty improves accuracy in detection of DE genes and isoforms. Finally, we develop a GamSeq-BDSeq RNA-seq analysis pipeline to facilitate users.