Improvement of the Parameterized Identification Model Using Quasi-Steady and Nonuniform Inflow Aerodynamic Model

Compared with those of a fixed-wing aircraft, the dynamics of a rotorcraft are significantly more complex. One of the major challenges in the design of an autonomous helicopter is the development of a flight dynamic model, which can be useful for simulation studies and for the design of control law and navigational aspects. There is always a trade-off from the accuracy of the mathematical model to the more simplified model required for a control design as far as the helicopter rotor/fuselage dynamics is concerned. Small-scale helicopters posses a higher bandwidth of dynamics; hence, models developed from the first principle alone do not fulfill the needs, and more-sophisticated mathematical models are thus required. The main objective of the present work is to improve the parameterized identification model by replacing it with a most-general flight dynamic model for a minihelicopter. This model includes the rotor blade flap dynamics, stabilizer bar dynamics, and vehicle dynamics, which will be applicable for a general maneuvering flight. A systematic study is undertaken to analyze the influence of inflow models and flap response on the helicopter trim. Stability of the minihelicopter is also analyzed; except for phugoid, all other modes are stable in hover and high forward flight conditions.     

High luminance YAG:Ce nanoparticles fabricated from urea added aqueous precursor by flame process

High luminance Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) nanoparticles were prepared from urea-added nitrate aqueous precursor by flame-assisted spray pyrolysis (FASP). The addition of urea into nitrate precursor plays an important role in YAG:Ce nanoparticle formation and in improving its optical performance. The decomposition and combustion of urea in the flame zone provides additional heat to the particles, which coupled with the evolution of large volumes of gasses, contributes to nanoparticle formation. The as-prepared nanoparticles are hexagonal YAlO₃, that are nearly spherical, rough on the surface and dense—and they can be converted to YAG:Ce after being annealed at 1200 °C for 4 h. The heat-treated particles are single crystalline, smooth in surface and dense with an average size around 50 nm. The optimum cerium-doping concentration of YAG:Ce nanoparticles is 4.0 at.%, which exhibits quantum efficiency of 45.0%. This quantum efficiency is comparable with that of YAG:Ce nanoparticles produced from other processes. The efficient emission of YAG:Ce nanoparticles also originates from a relatively good distribution of Ce ions incorporated into the host material of YAG as evidenced from the elemental mapping analysis.     

Cloning of the bile salt hydrolase (bsh) gene from Enterococcus faecium FAIR-E 345 and chromosomal location of bsh genes in food enterococci

Enterococcus faecium strain FAIR-E 345 isolated from food was shown to possess bile salt hydrolase (Bsh) activity in a plate screening assay and by high-performance liquid chromatography analysis. The bsh gene was cloned and sequenced. DNA sequence analysis revealed that it encoded a protein of 324 amino acids, with pI 4.877. A bsh gene probe was prepared from the cloned bsh gene and was used for probing plasmid and total genomic DNA of Bsh-positive enterococci isolated from food to determine the genomic location of their bsh genes. This probe was able to detect the bsh gene among total genomic DNA preparations but not from plasmid preparations of 10 plasmid-bearing Enterococcus strains. However, the probe could detect the bsh gene from total genomic DNA preparations of 12 Enterococcus strains that did not contain detectable plasmid DNA. In no cases did the probe hybridize with plasmid DNA preparations, suggesting that the bsh gene among enterococci is probably generally chromosomally encoded. This presumptive chromosomal location of bsh genes among food enterococci suggests that transfer of this trait by conjugative plasmids is unlikely.     

Genetic subsets regression

Subset regression procedures have been shown to provide better overall performance than stepwise regression procedures. However, due to the combinatorial nature of evaluating each potential subset, subset regression techniques are costly to use. To resolve this difficulty, the use of a simple genetic algorithm (GA) is proposed to reduce the number of subsets which must be evaluated. Any of a number of popular criteria, including Mallows' C_p, MSE, R², AIC, etc., can be used to drive the search strategy associated with the use of the GA. Several illustrated examples on its use are provided.     

High-dispersed MoO3 nanoparticles in 3D-dendritic mesoporous silica nanospheres: heterogeneous catalysts for the epoxidation of olefins

Journal of Porous Materials - Highly dispersed molybdenum trioxide were loaded in three-dimensional dendritic mesoporous silica nanospheres (MoO3@3D-DMSNs) by one-pot method. The mesoporous silica...     

A framework for GPU‐accelerated exploration of massive time‐varying rectilinear scalar volumes

We introduce a novel flexible approach to spatiotemporal exploration of rectilinear scalar volumes. Our out‐of‐core representation, based on per‐frame levels of hierarchically tiled non‐redundant 3D grids, efficiently supports spatiotemporal random access and streaming to the GPU in compressed formats. A novel low‐bitrate codec able to store into fixed‐size pages a variable‐rate approximation based on sparse coding with learned dictionaries is exploited to meet stringent bandwidth constraint during time‐critical operations, while a near‐lossless representation is employed to support high‐quality static frame rendering. A flexible high‐speed GPU decoder and raycasting framework mixes and matches GPU kernels performing parallel object‐space and image‐space operations for seamless support, on fat and thin clients, of different exploration use cases, including animation and temporal browsing, dynamic exploration of single frames, and high‐quality snapshots generated from near‐lossless data. The quality and performance of our approach are demonstrated on large data sets with thousands of multi‐billion‐voxel frames.     

Interactive Volumetric Visual Analysis of Glycogen‐derived Energy Absorption in Nanometric Brain Structures

Digital acquisition and processing techniques are changing the way neuroscience investigation is carried out. Emerging applications range from statistical analysis on image stacks to complex connectomics visual analysis tools targeted to develop and test hypotheses of brain development and activity. In this work, we focus on neuroenergetics, a field where neuroscientists analyze nanoscale brain morphology and relate energy consumption to glucose storage in form of glycogen granules. In order to facilitate the understanding of neuroenergetic mechanisms, we propose a novel customized pipeline for the visual analysis of nanometric‐level reconstructions based on electron microscopy image data. Our framework supports analysis tasks by combining i) a scalable volume visualization architecture able to selectively render image stacks and corresponding labelled data, ii) a method for highlighting distance‐based energy absorption probabilities in form of glow maps, and iii) a hybrid connectivitybased and absorption‐based interactive layout representation able to support queries for selective analysis of areas of interest and potential activity within the segmented datasets. This working pipeline is currently used in a variety of studies in the neuroenergetics domain. Here, we discuss a test case in which the framework was successfully used by domain scientists for the analysis of aging effects on glycogen metabolism, extracting knowledge from a series of nanoscale brain stacks of rodents somatosensory cortex.     

Observations on the Raynaud's disease

During the last 25 years, owing to the improvement of the diagnostic means, the cases of "Raynaud's phenomenon" with well known etiology have been increasing and according to some authors they should be considered clearly prevailing. Through a right prevention and a medical and surgical therapy it is possible to obtain significant results. Consequently it is important to carry out a diagnostic screening. A study concerns 68 cases have been carried out in the Institute of Vascular Surgery, University of Milan, during the period 1971-1974. The cases are divided in two groups: idiopathic forms (disease) and forms connected to identifiable etiologies (syndrome). Many of the clinical parameters studied are examined. The so-called idiopathic forms: 47 cases (69%) with an average age of 45 years and a clear female prevalence (33 against 14). The forms with an identifiable etiology: 21 (31%) with an average age of 31 years and a clear male prevalence (16 against 5). It is therefore observed that the idiopathic Raynaud's disease is still prevailing and particularly in women. In idiopathic forms brachial angiography shows in most of the cases X-ray evidence of digital artery occlusion.     

Formation of BaTiO3 nanoparticles from an aqueous precursor by flame-assisted spray pyrolysis

By manipulating process parameters, BaTiO₃ nanoparticles with tunable size were successfully prepared by flame-assisted spray pyrolysis (FASP) from an aqueous solution of barium acetate and titanium-tetra-isopropoxite. Particle size was controlled over a wide range (from about 23 to 71 nm) by varying the concentration of precursor and methane flow rate. Flame temperature was a key factor in producing particles with a narrow size distribution. The BaTiO₃ nanoparticles were cubic in crystal structure, dense, spherical and softly agglomerated. The particles contained OH, carboxyl and CO₂ bonding groups that could be completely removed by post-heat treatment. At room temperature, BaTiO₃ pellets had relatively high dielectric constants (2578.8–3611.8) with loss factors ranging from 2.6% to 7.1% at the frequency of 1 kHz. The results of this study indicate that BaTiO₃ nanoparticles can be fabricated using continuous and industrially applicable FASP.