Delta wing flutter based on doublet lattice method in NASTRAN

The subsonic doublet-lattice method (DLM) aeroelastic analysis in NASTRAN was successfully applied to produce subsonic flutter boundary data in parameter space for a large delta wing configuration. Computed flow velocity and flutter frequency values as functions of air density ratio, flow Mach number, and reduced frequency are tabulated. The relevance and the meaning of the calculated results are discussed. Several input-deck problems encountered and overcome are cited with the hope that they may be helpful to NASTRAN Rigid Format 45 users

Structural, Magnetic and Electrical Properties and Colossal Magnetoresistive Effect Of La0.67Sr0.33mno3 Perovskites With Dy Substitution At La Site

A thorough study on structural, magnetic and electrical properties and colossal magnetoresistive (CMR) effect in La0.67Sr0.33MnO3 or generically known as LSMO manganites substituted with dysprosium (Dy) at lanthanum (La) site is the main area of research in this thesis. In the first part of this work, the samples of (La1-xDyx)0.67Sr0.33MnO3 (LDSMO) with x=0.00-0.90 were synthesized using standard solid state reaction method. The second part involves the characterization of the samples using X-ray Diffractometer (XRD), Vibrating Sample Magnetometer (VSM), four point probe electrical resistivity and magnetoresistance measurement system, and Atomic Force Microscope (AFM). The XRD pattern for all samples reveals a single phase pattern with rhombohedral structure. When Dy concentration increases, the magnetization value at any given temperature decreases markedly. Moreover, the magnetization (temperature dependence of magnetization and isothermally hysteresis loop) show a prominent transition corresponding to Curie temperature,TC arising from long range ferromagnetic order to a short range nature with paramagnetic order (0.00≤≤x0.06), antiferromagnetic (x=0.90) and spin glass state (x=0.80). The electrical resistivity increases with the shifting of metal-insulator transition temperature, TMIT to lower temperature. Low temperature resistivity datas signify that the resistance of electrical transport mechanism in the metallic region can be ascribed as electron-electron scattering with minor attribution of magnon-electron scattering. On the other hand, the high temperature resistivity data satisfy the variable range hopping (VRH) model and small polaron hopping (SPH) model. The considerable change in the density of states at Fermi level, N(Ef) and activation energy, Ea which was obtained from fitting the electrical transport data, proved that the mobility of the electron decreases proportionally with Dy concentration. The N(Ef) values were found within the range of 1.53x1016 eV-1cm-3 to 1.45x1018 eV-1cm-3 whereas the Ea values were ranged from 2.96x102 meV to 1.32x103 meV. The TC-TMIT discrepancy is due to the fact that the former is an intrinsic characteristic, the latter depends strongly on the extrinsic factor e.g. grain size (grain boundary). The effect of grain size on the CMR mechanism is analyzed from AFM images. The grain size was found to decrease exponentially from 2.88 μm (x=0.00) to 1.34 μm (x=0.90) with the increase of Dy concentration. As the grain size decreases, the ratio of surface over volume increased. Hence, the influence of grain boundaries effect cannot be excluded and eliminated in all samples. Overall, negative CMR in ascending order had been obtained in all samples as decreasing temperature at low magnetic field. This phenomenon is known as Low Field Magnetoresistance (LFMR). Spin dependent scattering, spin polarization and tunneling between neighbouring grains and the magnetically disordered grain boundaries seems to be responsible for the LFMR effect. The highest CMR value with 62.2% is obtained in x=0.60 LDySMO sample at 90K

Preparation and Characterization of Carboxymethyl Sago Waste and its Hydrogel

Carboxymethyl sago waste (CMSW) was prepared under heterogeneous condition as the product of the sago waste and sodium monochloroacetate (SMCA) in presence of sodium hydroxide (NaOH). The carboxymethylation of sago waste was optimized respect to degree of substitution (DS) and reaction efficiency (RE). Maximum values of DS and RE were obtained with aqueous isopropyl alcohol as the reaction medium. Data obtained also suggest that water: isopropyl alcohol with 1:15 ratio was most appropriate for the reaction. The concentration of aqueous sodium hydroxide solution, which is used to activate the cellulose and starch was found optimal at 25 % (w/v). The increase of concentration of SMCA leads to an increase of DS, but only in certain extent, approaching a maximum value with anhydroglucose unit of sago waste: SMCA with 1:2.1 in molar ratio. The highest value of DS is being obtained when carboxymethylation was performed at an hour of alkalization and 2 hours etherification at temperature of 55 oC. The values of DS and RE under optimum condition for CMSW were 1.06 and 61.1% respectively. Sago waste were fractionated into cold water soluble (2.8%), hot water soluble (7.5%), 5% sodium hydroxide soluble polysaccharides (starch and hemicelluloses) (78.1%), 10% acetic acid and sodium chlorite (3.1%), 24% potassium hydroxide and 2% boric acid soluble hemicelluloses (1.9%) and -cellulose (10.5%), respectively. Moisture content, density, values of pH and solubility in water of CMSW were found higher than sago waste and these properties were enhanced by increasing the DS of CMSW. Fourier Transform Infrared Spectroscopy (FTIR) of CMSW revealed two new bands with sharp intensity at 1320 and 1422 cm-1, which respectively correspond to the vibration of substituted carboxyl groups (COO). Scanning electron microscopy studies showed that the sago waste consists of surface morphologies of cellulose fibres and smooth surface and oval granules of starch. After carboxymethylation, CMSW were rough and grooved with agglomeration of cellulose fibres and starch granules. Thermogravimetric analysis and differential thermogravimetric of CMSW showed the thermal stability of CMSW was more stable than sago waste from 35 to 900 oC. Results from differential scanning calorimetric revealed that the carboxymethylation reduced the crystallinity of starch and cellulose and reduced the portion of starch granules being able to be gelatinized in CMSW. Viscometry capillary study indicates that the degradation of the sago waste chains was occurred where the intrinsic viscosity and molecular weight of CMSW were found to be decreased after carboxymethylation. The CMSW hydrogels with various parameter of cross-linking were prepared by using electron beam irradiation. CMSW hydrogel with DS of 1.06, 80 % of CMSW aqueous solution and irradiation dose of 40 kGy showed the highest of gel content. The swelling of CMSW hydrogel decreased with the increase of the dose of irradiation and CMSW concentration. The swelling of CMSW hydrogel in water increases with increasing of hydrophilic substituents (–CH2COONa) in CMSW hydrogel. Swelling ratio of CMSW hydrogel in alkaline medium (0.1 M NaOH) and sodium chloride (0.1 M NaCl) were lower than swelling in deionized water but higher than acidic medium (0.1 M HCl). The presence of cations in swelling medium were remarkably affected the swelling ratio of CMSW hydrogel

How will disenfranchised Peoples adapt to Climate Change? Strengthening the Ecojustice Movement

The Fourth assessment of the Intergovernmental Panel on Climate Change (IPCC) acknowledged That millions of people are currently, and will increasingly be, affected by the impacts of climate change, in the form of floods, droughts and other extreme events, as well as related threats to food security. In response to these global environmental changes, the international community, including civil society, is acting on the need for immediate adaptation measures and is developing strategies for future adaptation. However, the impacts of climate change are unevenly distributed, with many of the poorest, most vulnerable peoples experiencing the immediate effects of climate change, in the here and now. As the IPCC noted, developing countries are disproportionately affected by climate change and often, the least able to adapt due to lack of infrastructure and resources

An automated method for comparing motion artifacts in cine four-dimensional computed tomography images.

The aim of this study is to develop an automated method to objectively compare motion artifacts in two four-dimensional computed tomography (4D CT) image sets, and identify the one that would appear to human observers with fewer or smaller artifacts. Our proposed method is based on the difference of the normalized correlation coefficients between edge slices at couch transitions, which we hypothesize may be a suitable metric to identify motion artifacts. We evaluated our method using ten pairs of 4D CT image sets that showed subtle differences in artifacts between images in a pair, which were identifiable by human observers. One set of 4D CT images was sorted using breathing traces in which our clinically implemented 4D CT sorting software miscalculated the respiratory phase, which expectedly led to artifacts in the images. The other set of images consisted of the same images; however, these were sorted using the same breathing traces but with corrected phases. Next we calculated the normalized correlation coefficients between edge slices at all couch transitions for all respiratory phases in both image sets to evaluate for motion artifacts. For nine image set pairs, our method identified the 4D CT sets sorted using the breathing traces with the corrected respiratory phase to result in images with fewer or smaller artifacts, whereas for one image pair, no difference was noted. Two observers independently assessed the accuracy of our method. Both observers identified 9 image sets that were sorted using the breathing traces with corrected respiratory phase as having fewer or smaller artifacts. In summary, using the 4D CT data of ten pairs of 4D CT image sets, we have demonstrated proof of principle that our method is able to replicate the results of two human observers in identifying the image set with fewer or smaller artifacts

Tables of electrostatic structure of near wakes behind space probes at the mesothermal speeds

Tabular data for electrostatic structure of disturbed region behind moving bodies in collisionless plasma for sphere and long circular cylinde

ForestQC: Quality control on genetic variants from next-generation sequencing data using random forest.

Next-generation sequencing technology (NGS) enables the discovery of nearly all genetic variants present in a genome. A subset of these variants, however, may have poor sequencing quality due to limitations in NGS or variant callers. In genetic studies that analyze a large number of sequenced individuals, it is critical to detect and remove those variants with poor quality as they may cause spurious findings. In this paper, we present ForestQC, a statistical tool for performing quality control on variants identified from NGS data by combining a traditional filtering approach and a machine learning approach. Our software uses the information on sequencing quality, such as sequencing depth, genotyping quality, and GC contents, to predict whether a particular variant is likely to be false-positive. To evaluate ForestQC, we applied it to two whole-genome sequencing datasets where one dataset consists of related individuals from families while the other consists of unrelated individuals. Results indicate that ForestQC outperforms widely used methods for performing quality control on variants such as VQSR of GATK by considerably improving the quality of variants to be included in the analysis. ForestQC is also very efficient, and hence can be applied to large sequencing datasets. We conclude that combining a machine learning algorithm trained with sequencing quality information and the filtering approach is a practical approach to perform quality control on genetic variants from sequencing data

Building bridges in development: Five recommendations to connect the islands of research, policy and practice.

Elizabeth Harrison, Eleanor Jew, Thomas Smith, Iqbal Ahmed and Sarah Peck present the recommendations from a recent conference for early-career researchers on bridging the gap in development research, policy and practice. Participants were encouraged to consider partnership-based solutions to development problems. From having a realistic understanding of intended outcomes to formulating relevant research questions, constructive debate took place on how best to navigate and undertake practical solutions to developing dialogue across sectors

Implicit large-eddy simulation of a wingtip vortex

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordIn this article, recent developments in numerical methods for performing a large-eddy simulation of the formation and evolution of a wingtip vortex are presented. The development of these vortices in the near wake, in combination with the large Reynolds numbers present in these cases, makes these types of test cases particularly challenging to investigate numerically. First, an overview is given of the spectral vanishing viscosity/implicit large-eddy simulation solver that is used to perform the simulations, and techniques are highlighted that have been adopted to solve various numerical issues that arise when studying such cases. To demonstrate the method's viability, results are presented from numerical simulations of flow over a NACA 0012 profile wingtip at R ec = 1.2 × 10 6 and they are compared against experimental data, which is to date the highest Reynolds number achieved for a large-eddy simulation that has been correlated with experiments for this test case. The model in this paper correlates favorably with experiment, both for the characteristic jetting in the primary vortex and pressure distribution on the wing surface. The proposed method is of general interest for the modeling of transitioning vortex-dominated flows over complex geometries.The authors acknowledge support from the United Kingdom Turbulence Consortium (UKTC) under grant EP/L000261/1 as well as from the Engineering and Physical Sciences Research Council (EPSRC) for access to ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). DM acknowledges supported by the Laminar Flow Control Centre funded by Airbus/EADS and EPSRC under grant EP/I037946. SJS additionally acknowledges Royal Academy of Engineering support under their research chair scheme. We also acknowledge the support from the Imperial College London High Performance Computing facilities