Aspects relevant for operational and structural design of a wide-breadth, neo-panmax containership were addressed. First, speed loss in waves was investigated. Second, wave-induced global hull girder torsion was determined to assess the effects of the increased breadth on this load component, generally considered critical for the ship’s structural strength. An extended Reynolds-averaged Navier–Stokes (RANS) equations solver simulated the ship advancing in calm water as well as in selected regular head and bow waves. A boundary element method (BEM) computed transfer functions of wave-induced ship response. Before using spectral techniques to obtain long-term predictions of hull girder torsion, these transfer functions were corrected to account for non-linear effects. To assess the reliability of the computed long-term hull girder torsion, the extended RANS equations solver was used to perform additional simulations for this ship advancing at selected speeds in equivalent regular design waves that represent wave conditions considered critical for structural design. Except for the very forward part of the ship, long-term BEM-based predictions of wave-induced hull girder torsion did not exceed rule values. Comparative BEM and RANS predictions of hull girder torsion differed significantly, underlining the need to validate the predictions systematically.

ExxonMobil Canada Properties and its collaborators are building a gravity based structure (GBS) in Newfoundland and Labrador to be installed on the Hebron Field offshore Eastern Canada. The geometry of the Hebron GBS is driven by the design constraints of a long operating life placed on the seafloor in the harsh environments at the Hebron field location. Prior to installation, the GBS encounters a number of significant floating phases — deep-water construction, towage, and installation. In each of these stages the hydrodynamic character of the unique Hebron geometry must be quantified to predict dynamic motions, assess tow performance, and define installation procedures and limitations. For the floating GBS, both heave and roll natural periods are long, and resonant responses due to wind gusting and vertical wave drift take place. Assessing the hydrodynamics by industry standard empirical methods is insufficient as regards capturing the viscous damping generated by eddy formation off the sharp edges of the submerged GBS structure. This paper focuses on the utilization of Computational Fluid Dynamics (CFD) to better understand and quantify this viscous damping. The Hebron GBS work has challenged the traditional methods for model generation and use of CFD for damping estimation, primarily because these techniques are most frequently used for traditional hull shapes. For example, application of the overset mesh technique, as successfully applied for ship-shaped vessels, does not provide the required accuracy in this case. Alternative numerical models are tested and found to work well: morphing techniques and sliding meshes for heave and pitch, respectively. Based on convergence and sensitivity studies, the results are accepted. Ultimately, the CFD work allows the project to quantify the expected increases in hydrodynamic damping and progress in the process of improving predictions of GBS motions and thus optimizing the operational planning of towing and installation.

Background and study aims: Endoscopic submucosal dissection (ESD) is a recognized method for the curative treatment of superficial neoplasia, but its use is limited by lengthy procedures and the lack of versatility of existing knives. We developed a prototype ESD device with the ability to work as a needle, hook, or “scythe.” This new device was compared to regular ESD knives in a randomized animal study. Patients and methods: Eight pigs underwent two gastric ESD procedures each, similar in size and difficulty, one with a regular ESD device and the other with the new device. The order and location of each ESD, as well as the performing operator, were randomized. Primary judgment criterion was safety of procedures. Overall and submucosal dissection procedure times were measured. Time-to-surface ratios were measured and estimated for ESDs larger than those performed. Histopathology of the resected tissue and remaining stomach was done after each experiment. Results: No complications were observed throughout the study and all resections were completed en-bloc and uneventfully. The submucosal extension of resections was similar with both the standard and the new devices. A comparison of time-consumption between groups did not show statistically significant differences, but a dramatic reduction of procedure duration was observed in some procedures with the new device; based on observed data, a potential time-saving of up to 66 % was anticipated, with a relatively short learning curve. Conclusions: This new versatile device proved to be as safe as regular ESD knives, and seems likely to help reduce the duration of the procedure.

No abstract