A Return to the Basics: Constitutional Answers to the Racial Gerrymandering Questions

This comment seeks to explain the incorrigible by returning to the basics. Starting and ending at the Constitution and a notion of what it means to be represented, this comment traces the development of redistricting jurisprudence from the Fourteenth and Fifteenth Amendments through the Voting Rights Act and finally to the Supreme Court. Most notably, this comment focuses on the effects of the redistricting quagmire on the state ofNorth Carolina throughout the 1990\u27s as an exemplar of a reapportionment process attempting to pander to the political proclivities of both the Department of Justice and the Judicial branch

A Return to the Basics: Constitutional Answers to the Racial Gerrymandering Questions

This comment seeks to explain the incorrigible by returning to the basics. Starting and ending at the Constitution and a notion of what it means to be represented, this comment traces the development of redistricting jurisprudence from the Fourteenth and Fifteenth Amendments through the Voting Rights Act and finally to the Supreme Court. Most notably, this comment focuses on the effects of the redistricting quagmire on the state ofNorth Carolina throughout the 1990\u27s as an exemplar of a reapportionment process attempting to pander to the political proclivities of both the Department of Justice and the Judicial branch

Modelling Risers With Partial Strake Coverage

This paper compares model test data for risers with partial strake coverage to predictions made with the Vortex-Induced Vibration (VIV) prediction program SHEAR7 Versions 4.5 and 4.6. It is shown that new features in Version 4.6 substantially enhance the capability for predicting the VIV response of risers with partial coverage. Experimental data is taken from two large L/D tests: the NDP 38 m long riser tests and the Deepstar-Miami, 500 foot long riser. New methods are described for modeling risers partially covered with helical strakes. Key SHEAR7 parameters are recommended, based on parametric investigations to calibrate the model against the available experimental data. Recommended modeling procedures are described so as to facilitate implementation by SHEAR7 users in their VIV modeling tasks.SHEAR7 JI

Response Variability in Flexible Cylinder VIV Model Test Data

This paper presents some results from the 2011 SHELL tests at the MARINTEK basin. The tests involved towing densely instrumented 38m long flexible cylinders at Reynolds numbers up to 220,000. The main objective it to present the experimental results in a manner that describes the response variability that exists in the measured response data. Despite the fact that VIV is known to be a stochastic process, this is rarely addressed in the literature and currently there is no framework or 'best-practice' in the VIV community that can address statistically non-stationary data. In this paper, the experimental measurements are treated like non-stationary time-series and all statistical quantities which are typically of interest are computed with the use of short duration moving windows (or time-gates). A novel way of plotting and presenting VIV response data for flexible cylinders is introduced that is capable of revealing the inherent variability that exists in the cylinder's response.SHEAR7 Joint Industry Projec

The Identification of Power-In Region in Vortex-Induced Vibration of Flexible Cylinders

This paper proposes a novel method to identify the power-in regions of long flexible cylinders subjected to vortex-induced vibration (VIV). It also attempts to address a practical problem: “Will a secondary power-in region appear after the primary power-in region is covered with suppression devices?” The source of data is a recent model test on a 38 meter long flexible cylinder, densely instrumented with fiber optic strain gauges and accelerometers. For pipes with partial coverage of suppression devices in uniform flow, the bare region would be expected to be a power-in region and the section with suppression devices is expected to be a power-out region. Experimental data from these types of tests are used to benchmark the proposed power-in zone identification method. The method is then used to identify the power-in zones on a bare cylinder in a sheared flow. This paper also explores the occurrence of secondary power-in regions that may exist, when suppression devices are placed in the primary power-in zone. Secondary power-in regions were observed. Lessons learned from the power-in region identification in sheared flows will be a useful tool for designer/engineers choosing where to place suppression devices.DeepStar (Consortium)SHEAR7 JI

Effects of Strake Coverage and Marine Growth on Flexible Cylinder Vortex-Induced Vibrations

This paper presents some results from the recent SHELL tests at the MARINTEK basin. The tests involved towing densely instrumented flexible cylinders at Reynolds numbers up to 220,000. The main objective is to present the experimental results describing the effectiveness of different amounts of strake coverage and to explore the influence of simulated marine growth. The data are presented in terms of cross-flow (CF) response amplitudes and rainflow-counted damage rates due to the combined CF and in-line (IL) bending stresses. All the results are compared with the bare cylinder cases which will be used as a reference to determine how effective the strakes are in suppressing vortex-induced vibrations (VIV) and how this effectiveness can be affected by marine growth. The results show that even small bare sections (missing strakes) can lead to significant VIV response. Finally, the tests revealed that even moderate amounts of marine growth can quickly negate any suppression coming from the strakes.SHEAR7 JI

Reynolds Number Effects on the Vortex-Induced Vibration of Flexible Marine Risers

This paper explores the Reynolds number dependence of the Vortex-Induced Vibration (VIV) of flexible marine risers. Emphasis is placed on revealing the trends that exist between the Strouhal number and the Reynolds number and between the dimensionless amplitude (A/D) and Reynolds number. Data is drawn from recent towing tank experiments which used flexible cylinders of three different diameters. The 38m long pipes were exposed to uniform and sheared currents. The Reynolds number range extended from approximately 5,000 to 220,000 — well into the critical regime — with the larger diameter pipes responding in up to the 13th mode and the smaller diameter pipe responding well above the 20th mode. The results and trends from this set of experiments are compared to previous results from laboratory and field experiments.SHEAR7 JI