Transition in a disturbed environment

The title of this presentation is the title of our research grant. While transition study is the objective of the work, the results to date are principally on the properties of turbulent boundary layers at low Reynolds numbers are discussed. Testing was done in a small return wind tunnel. Mean boundary layer development is given. The skin friction behavior of the turbulent points are considered. No standard laminar flow was observed. Furthermore, the turbulent mean flow data seem reasonable for the elevated disturbance levels of the tests in the sense that there is no discernible wake component to any of the profiles and that the variation of skin friction with R sub theta is consistent with zero wake strength. The no-grid data are in all likelihood transitional

The ISSC 2022 committee III.1-Ultimate strength benchmark study on the ultimate limit state analysis of a stiffened plate structure subjected to uniaxial compressive loads

This paper presents a benchmark study on the ultimate limit state analysis of a stiffened plate structure subjected to uniaxial compressive loads, initiated and coordinated by the ISSC 2022 technical committee III.1-Ultimate Strength. The overall objective of the benchmark is to establish predictions of the buckling collapse and ultimate strength of stiffened plate structures subjected to compressive loads. Participants were asked to perform ultimate strength predictions for a full-scale reference experiment on a stiffened steel plate structure utilizing any combination of class rules, guidelines, numerical approaches and simulation procedures as they saw fit. The benchmark study was carried out blind and divided into three phases. In the first phase, only descriptions of the experimental setup, the geometry of the reference structure, and the nominal material specifications were distributed. In the second phase, the actual properties of the reference structure were included. In the third and final phase, all available information on the reference structure and measured properties were distributed, including the material properties and laser-scanned geometry. This paper presents the results obtained from seventeen submitted FE simulations as well as details on the experiment. It also presents comparisons of the force versus the displacement curve, failure modes and locations for each phase, among others, and a discussion on the participants’ ability to predict the characteristics of the reference experiment with the information that is available for the phase. The outcome of the study is a discussion and recommendations regarding the design of finite element models for the ultimate state analysis of stiffened plate structures, with emphasis on the prediction of the ultimate capacity, force-displacement curve, and failure mode and location related to access to data, uncertainties and modeling of the material properties, geometric imperfections and distortions, and residual stresses

Finite element modeling for the progressive collapse analysis of steel stiffened-plate structures in fires

In this study, novel honeycomb structures with twisted feature were designed and manufactured by laser powder bed fusion (LPBF). The manufacturability, microstructure evolution of LPBFed honeycomb components with twisted feature were studied. The influence of twist angle on the compressive behavior of components was experimentally investigated and the underlying mechanism was revealed using FE simulation. Results revealed that the material relative density of LPBFed components was reduced with the increase of twist angle, caused by the enlarging overhanging area. Different cooling rate of melt pool at different parts along the building direction resulted in different microstructures. The twist angle significantly affected the compressive behaviors of honeycomb structures. When the cell number along each side was 3, the honeycomb structure with 30° twist angle exhibited the most uniform stress distribution under compression, leading to the highest specific compressive strength and energy absorption ability. The influence of cell number and wall thickness on compressive properties of honeycomb structures with 30° twist angle were investigated through finite element simulation, and results revealed that the structure with 0.75 mm wall thickness and 3 unit cells along each side showed the highest specific energy absorption ability

Effect of Mooring Line Layout on the Loads of Ship-shaped Offshore Installations

An offshore mooring system stations a ship-shaped offshore installation in place while withstanding incoming loads from the marine environment with short-term and long-term uncertainties. This study aims to develop a novel framework for analysing the loads on floating systems, namely mooring line tension, mooring line fatigue damage, and hull bending moment, as a function of the mooring layout design variables and environmental random variables. The nonlinear influence of those variables is assessed by means of advanced techniques using response charts, response divergence charts, and Sobol's total-effect sensitivity indexes. The developed procedure includes a probabilistic selection of mooring scenarios, station-keeping numerical analyses, and metamodel selection to define input loads. An example of a hypothetical floating production storage and offloading (FPSO) unit with taut legs in the Gulf of Mexico illustrates the procedure. The details of the computations are documented, and the findings show that the mooring line top-tension has a high total-effect index for the wave-induced bending moment and the total mooring line tension, whereas the fatigue damage is mostly affected by the chain diameter. The results of this research offer useful insights to designers and propose the use of a surrogate model to be used in the reliability-based design of mooring systems

Ecogeographical variations of chromosomal polymorphism in Hawaiian populations of Drosophila immigrans

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.Eighteen samples from twelve populations of Drosophila immigrans in the islands of Kauai, Oahu and Hawaii in the Hawaiian archipelago were analyzed for inversion polymorphism in 1125 females and 206 males. Three kinds of second chromosome inversions, which appear to be identical with those previously reported by other workers, were present in all of our populations; two other new inversions of the same autosome were detected from the Hawaii collections, but their origin, whether natural or laboratory, could not be assured. The average proportion of inversion heterozygosity per individual of the populations from Kauai, Oahu and Hawaii was about 34%, 32% and 65% respectively. The frequencies of heterozygous inversions Here similar between different populations within islands (with one notable exception on Hawaii). In contrast, the frequencies were significantly heterogeneous from one island to the next. The results of gene arrangement frequency analysis consolidated the above findings. It is suggested that the inter-island differentiations are due to natural selection and probably maintained by the isolation by oceanic channels. Two near-by localities on Hawaii were inhabited with significantly heterogeneous populations. Such a microgeographic differentiation has been interpreted as being due to the presence of highly localized, differential selection forces in the two localities, and the difference seems to be maintained due to isolation by the lava flows. Our data suggest that the breeding units of Hawaiian populations of D. immigrans are not so small as to allow for genetic drift to significantly affect the populations. Inversion polymorphism was similar between females and males taken at the same time in the same localities

Histone Deacetylase Inhibitors in Malignant Pleural Mesothelioma: Preclinical Rationale and Clinical Trials

AbstractMalignant pleural mesothelioma (MPM) is a rare and aggressive cancer of the mesothelium with only a limited range of treatment options that are largely ineffective in improving survival. Recent efforts have turned toward the analysis of specific, dysregulated biologic pathways for insight into new treatment targets. Epigenetic regulation of tumor suppressor genes through chromatin condensation and decondensation has emerged as an important mechanism that leads to tumorogenesis. A family of histone acetyltransferases and deacetylases regulates this balance, with the latter facilitating chromatin condensation, thus preventing gene transcription, resulting in the loss of heterozygosity of tumor suppressors. Inhibition of this process, coupled with a similar inhibition of nonhistone protein deacetylation, ultimately leads to the promotion of apoptosis, cell cycle arrest, and inhibition of angiogenesis. An increasing amount of preclinical data highlighting the effectiveness of histone deacetylase inhibition in MPM cell lines and mouse xenograft models has led to a number of early phase clinical trials in patients with MPM. The results of these efforts have led to a multicenter, randomized, placebo-controlled phase III study of the histone deacetylase inhibitor vorinostat in patients with advanced MPM, offering hope for a new and effective therapy in patients with this disease