Vortex Induced Vibrations (VIV) of Spars under current flow is an important consideration of Spar mooring design. Model tests and Field data show that Spar VIV is a complex issue that can involve a large number of parameters which include Spar hull characteristics, dynamic characteristics of the moored system and current characteristics itself (profile, turbulence, direction). The Cell Spar is a new design that has several physical characteristics that are different than those of the present classic and truss Spars. Some of these characteristics allow the structure to be constructed in a manner that does not degrade the VIV performance in currents. A series of model tests were performed to study the effects of Spar hull and mooring system characteristics on the VIV response of the Cell Spar. This paper presents an overview of the tow tank model tests and the VIV response that was measured. The paper describes in detail the experimental setup and the Spar details that were altered to achieve a VIV response that is superior to all existing Spars. Introduction A new configuration of a Spar platform called the Cell Spar is presently being fabricated in Texas. This new hull form is composed of a bundle of cylindrical members called cells that are held together by a number of horizontal and vertical structural elements located in the interstitial space between the cells (see Figure 1). Since the outer surface of the upper portion of the Cell Spar does not form a regular cylinder, there was a concern that the strakes used on the existing Spars might not work. In addition, it is more difficult to fabricate the conventional Spar strake members to fit on the multisurfaced exterior of the Cell Spar. A number of plausible new strake configurations were proposed as possible solutions, but since VIV-suppression effectiveness has proven to be difficult to predict, a series of model tests were conducted to adequately quantify performance. This paper describes the various strake configurations that were tested and presents the VIV test results that were obtained. Figure 1 Sketch of the Cell Spar Platform.(AVAILABLE IN FULL PAPER) Description of Cell Spar The upper portion of the Cell Spar under construction is composed of six outer cells surrounding a central cell. These upper cells provide the buoyancy required to float the vessel. The lower portion of the Spar is formed by extending three of the outer cells down to the keel. Fixed ballast is contained within the bottom portion of these legs to ensure that the structure has adequate stability. Like the existing Spars the structure is unconditionally stable since the center of buoyancy is above the center of gravity.

Objects: Anterior cervical plating decreases the risk of pseudarthrosis, increases rate of fusion following anterior cervical discectomy and fusion (ACDF). Dysphagia is a common complication of ACDF, with the anterior plate implicated as a potential contributor. A zero-prole, stand-alone interbody spacer has been postulated to minimize soft-tissue irritation and postoperative dysphagia, but studies are limited. We are reporting our ndings in term of clinico-radiological outcomes following the use of such devices in the treatment of cervical spine degenerative diseases with a focus on the course of postoperative prevertebral soft-tissue thickness and the incidence of dysphagia. The authors conducted a prospective analysis of all Methods: patients who had undergone ACDF between December 2018 and December 2019. All patients received a Zero-P implant (DePuy Synthes Spine).The Neck Disability Index (NDI),Modied Japanese Orthopaedic Association Score(mJOA) and visual analog scale (VAS) scores for arm and neck pain were documented. Dysphagia was determined using the Bazaz criteria. Prevertebral soft-tissue thickness, spinal alignment, intervertebral disc height were assessed as well. The nal outcome was assessed with Odom's criteria. Total 30 patients Results: were studied prospectively, and data were collected and analyzed. 17 male and 13 female consecutive patients, with a mean age of 48.28 ± 8.17 years, underwent ACDF with Zero-Prole spacer (42 total operated levels) in the dened study period. There were signicant improvements in neck and arm VAS scores, the NDI and mJOA scores following surgery at last follow up. The neck VAS score improved from a mean 7.34 ±1.87 to 1.04 ± 0.09 (p<0.01) . The arm VAS score improved from 7.22±2.03 to1.03±0.10 at latest follow up. NDI score improved signicantly from preoperative 31.94±6.73 to 12.87±5.24 and mJOAscore improved from preoperative 9.53±1.98 to 15.6±1.26 at last follow up. Immediate postoperative dysphagia was experienced by 36.67% of all patients. Complete resolution of dysphagia was demonstrated at the latest follow-up. Prevertebral soft-tissue thickness at postoperative 48 hrs decreased across all levels from a mean of 15.87 ±0.69 to 11.81 ± 0.53 mm at last follow up. Cervical alignment and intervertebral disc height were also improved signicantly after surgery. Radiographic fusion was achieved in 100% of implants. No correlation was found between prevertebral soft-tissue thickness and Bazaz dysphagia score. Majority of the patients had excellent outcomes in odom's criteria. Conclusions: Zero-Prole device is a safe and effective alternative for the treatment of cervical degenerative diseases. Chronic dysphagia rates are comparable to or better than those for previously published case series.

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