Modal Parameters Identification of A Real Offshore Platform From the Response Excited by Natural Ice Loading

This paper investigates the possibility of utilizing response from natural ice loading for modal parameter identification of real offshore platforms.The test platform is the JZ20-2 MUQ jacket platform located in the Liaodong Bay,China.A field experiment is carried out in winter season,as the platform is excited by floating ices.The feasibility is demonstrated by the acceleration response of two different segments.By the SSI-data method,the modal frequencies and damping ratios of four structural modes can be successfully identified from both segments.The estimated information from both segments is almost identical,which demonstrates that the modal identification is trustworthy.Furthermore,by taking the Jacket platform as a benchmark,the numerical performance of five popular time-domain EMA methods is systematically compared from different viewpoints.The comparisons are categorized as:(1)stochastic methods versus deterministic methods;(2)high-order methods versus low-order methods;(3)data-driven versus covariance-driven stochastic subspace identification methods.

Natural orifice transluminal endoscopic surgery:Where are we going?

The foundation for natural orifice transluminal endoscopic surgery(NOTES) is to access the peritoneal and other body cavities through the wall of the alimentary tract via natural orifices,with the goal of performing procedures within the peritoneum and other cavities,without the need to make incisions in the abdominal wall.We have made great progress in the field of NOTES since the publication of the White Paper in 2006.There are still major fundamental goals as outlined by the Society of American Gastrointestinal and Endoscopic Surgeons/American Society for Gastrointestinal Endoscopy joint committee that need to be evaluated and answered before NOTES is ready for widespread clinical use.These include prevention of infection,instrument development,creation of a multitasking platform,and the ability to recognize and treat intraperitoneal complications such as hemorrhage and other physiological adverse events.In response to this need,recent abstracts and papers have focused on the management of intraoperative complications.The next phase is to focus on controlled prospective multicenter clinical trials that compare defined NOTES procedure to standard laparoscopy.The goal is to produce reliable and convincing data for the United States Food and Drug Administration,insurance companies,the physician community and the general public.At the present time,we still have many important milestones that still need to be met.Most investigators agree that a hybrid technique and not a pure NOTES practice should be advocated until devices can meet the current and new challenges in this f ield.