Flight Technique Research Articles

Poly-(3-ethyl-3-hydroxymethyl)oxetanes-Synthesis and Adhesive Interactions with Polar Substrates.

Hyperbranched polyoxetanes are a relatively new class of polymers. These are branched polyethers that are synthesized from oxetanes—four-member cyclic ethers bearing hydroxymethyl groups—via ring-opening polymerization. Four series of polyoxetanes were synthesized from 3-ethyl-3-(hydroxymethyl)oxetane and 1,1,1-tris(hydroxymethyl)propane as a core molecule. Reagents ratios ranged from 1:5 to 1:50, theoretical molar mass ranged from 714 g/mol to 5942 g/mol, and dispersities ranged from 1.77 to 3.75. The morphology of the macromolecules was investigated by a matrix-assisted laser desorption/ionization time of flight technique. The polyoxetanes’ adhesive interactions with polar materials were analyzed and provided results as follows: the work of adhesion was 101–105 mJ/m2, the bond-line tensile shear strengths were 0.39–1.32 MPa, and there was a brittle fracture mode within the polymer. The findings confirmed a good adhesion to polar substrates, but further research on polyoxetane modifications toward a reduction of brittleness is necessary.

A band selection approach based on Lévy sine cosine algorithm and alternative distribution for hyperspectral image

ABSTRACT Hyperspectral image (HSI) has become one of the most important remote sensing techniques for object interpretation by its abundant band information. As the data dimension increases, band selection technique is utilized to achieve the highest possible classification accuracy with fewer bands. Essentially, it is considered as an NP-hard problem, which is a non-deterministic problem within polynomial complexity and difficult to achieve a satisfactory solution using traditional search methods. Sine cosine algorithm (SCA) is a recently developed swarm intelligence algorithm based on the calculation of sine and cosine functions. To determine the parameters setting in SCA, Lévy flight technique is employed to improve the exploitation phase of the algorithm. In the paper, a new band selection method on the basis of SCA with a Lévy flight is proposed, and an alternative distribution is utilized to decrease the band dimension of HSI. In addition, crossover operation is conducted to enhance the optimal bits of each individual, and an evaluation criterion for assessing the performance of band selection is defined, allowing the classification accuracy and selected number of bands to be as balanced as possible. Experimental results demonstrate that the proposed band selection method is superior to other state-of-the-art approaches in terms of band subsets that achieve higher classification accuracy.

Investigation of the neutron-gamma ray discrimination performance at low neutron energy of a solution-grown stilbene scintillator

The results of experiments performed with a Ø25 x 25 mm solution-grown stilbene crystal in mono-energetic neutron fields in the 80-to-230 keV energy range are presented. The goal of the measurements, performed at the AMANDE facility, was to explore the capabilities of this organic scintillator to measure neutrons at the lowest possible energy with good pulse shape discrimination (PSD). The time of flight (TOF) technique was used in order to help with the neutron-gamma discrimination. The data are collected via a programmable digital acquisition (DAQ) system CAEN DT7530 using the software CoMPASS with the charge comparison method (CCM). The data are analysed using post-processing codes developed in the ROOT environment. The results show that the stilbene detector has discrimination capabilities for energies as low as 80 keV.

Application of the Vernier method for absolute distance metrology with CW TOF phase shift technique

A phase shift time of flight technique determines a position by comparing the phase angle of a continuously modulated signal in the source and its reflection on a target. However, due to its cyclical properties, the position information is contained within an ambiguity interval. For an absolute measurement, this interval is repeated N times plus a residual part given by the phase shift. In this work we propose an application of the Vernier method to determine N and a setup for mid-range applications (10-20) m with a 3 GHz amplitude modulated source to allow accuracies ≤ 100 μm.

Combined gamma-ray and energy-selective neutron radiography at CSNS

Combined photon and neutron radiography can integrate merits of X/gamma-ray radiography and energy-selective neutron radiography and has the potential of simultaneously visualizing objects composed of high-Z materials, low-Z materials and particular isotopes that resonantly absorb neutrons at certain energies. Intense pulsed gamma bursts and wide energy spectrum neutrons at spallation sources provide a unique opportunity to perform such combined radiography research. We present the results of the combined radiography experiments performed at the back-streaming white neutron (back-n) beamline at China Spallation Neutron Source (CSNS). Gamma-ray and energy-selective neutron radiographic images of multi-element samples were taken by an ICCD camera coupled with scintillators using the time of flight (TOF) technique. High-Z (Pb, Au, W, Ta, et al.) components were visualized with the intense gamma-ray bursts. The low-Z (10B) component was confirmed with varied image contrast when neutrons with varied energies were selected. The specific elements (natIn, 197Au and natW) were identified with neutrons at corresponding resonant energies. The experimental results prove the potential for simultaneously visualizing and identifying high-Z materials, low-Z materials and particular nuclides via combined X-ray radiography and energy-selective neutron radiography.

Rapid Identification of Carbapenemase-producing Klebsiella pneumoniae strains by Matrix-Assisted Laser Desorption/Ionization-Time of Flight using Vitek® Mass Spectrometry System.

The analysis of the protein pattern of Klebsiella pneumoniae carbapenemase (KPC)-producing strains by Bruker Matrix-Assisted Laser Desorption Ionization (MALDI) Biotyper system has revealed the presence, in the majority of cases, of an 11.109 m/z peak. The peak corresponds to the gene product named p019 of the bla KPC-bearing plasmids and has been suggested as a candidate for a biomarker that is able to distinguish KPC-producers from non-KPC-producers. The aim of this study was to evaluate the rapid detection of the 11.109 m/z peak of KPC-producer strains in the clinical laboratory routine by Matrix-Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) technique, using the Vitek® Research-User-Only (RUO) Mass Spectrometry (MS) system without changing the instrument parameters. Globally, 373 K. pneumoniae isolates were investigated and identified by MALDI-TOF MS analysis. KPC-producers were distinguished from non-KPC-producers by Antimicrobial Susceptibility Testing (AST) and phenotypic carbapenemase resistance assays. The MALDI-TOF Vitek MS RUO detected the 11.109 m/z peak in 95.7% of KPC-producers with 100% specificity before traditional test results became available. Our approach is appropriate as a first screening step for the rapid identification of KPC isolates, which will help to improve infection control in clinical practice and prevent the outbreak and dissemination of resistant bacteria.

Adaptive differential search algorithm with multi-strategies for global optimization problems

Differential search (DSA) is a recently proposed evolutionary algorithm mimicking the Brownian motion-like random movement existing in living beings. Though it has displayed promise for global optimization, the original DSA suffers from relatively poor search capability, especially for exploitation. In this study, an augmented DSA (ADSA) is proposed by integrating memetic framework with multiple strategies. In ADSA, a sub-gradient strategy is combined to improve local exploitation, and the dynamic Levy flight technique is developed to strengthen the global exploration. Moreover, a mutation operator based on differential search is used to increase swarm diversity. An intelligent selection method is implemented to adaptively adjust the strategies based on historical performance. To fully benchmark the proposed algorithm, 35 test functions of various properties in 30-D and 100-D are adopted in numerical experiments. Seven canonical optimization algorithms are involved for experimental comparison. In addition, two real-world problems are also tested to verify ADSA’s practical applicability. Numerical results reveal the efficiency and effectiveness of ADSA.

The Effect of Indium Doping on Deep Level Defects and Electrical Properties of CdZnTe

CdZnTe (CZT) ingots doped with different concentrations of indium (2 ppm, 5 ppm, 8 ppm, and 11 ppm) were grown by the Vertical Bridgman Method. The charge transport behaviors of CZT wafers were characterized by Thermally Stimulated Current (TSC), Time of Flight technique (TOF) and Current–Voltage measurements (I–V). TSC results indicate that the concentration of deep donor defects $$ {\hbox{Te}}_{\rm{Cd}}^{{ 2 { + }}} $$ is reduced significantly by increasing indium dopant content from 2 ppm to 8 ppm, while that of indium related traps, $$ {\hbox{In}}_{\rm{Cd}}^{ + } $$ and A-centers, is sharply increased. Hecht fitting and TOF results indicate that the electron mobility keeps nearly unchanged for different dopant concentrations in the region between 2 ppm and 5 ppm, but the lifetime increased greatly with increasing indium dopant concentration. Therefore, (μτ)e value was increased with higher indium dopant. The up-shift of Fermi level is also observed in the temperature-dependent I–V result with the increasing of indium dopant content. Large Schottky barriers are found in detectors with higher indium concentration. High voltage x-ray response results show that the channel number shifts to the low energy side for 2 ppm dopant samples compared with best performance 5 ppm dopant samples, while the full-energy peaks are broadened for 8 ppm and 11 ppm dopant samples.

Effect of Ga substitution for In in LiInSe2 crystals on carrier transport behaviors and alpha particles detection

Due to high density of 6Li isotope and the ability to respond to ionizing radiation through direct charge carrier transport, Li-containing chalcogenides are expected to be the replacement of 3He-tube or neutron reactive material coated semiconductor films for thermal neutron detection. However, the neutron detection efficiency of 6LiInSe2 is limited to 82% ascribed to that 115In isotope captures neutrons and generates gamma rays, which deteriorated the neutron response. Neutron detection efficiency could be improved by gallium substitution since its low neutron capture cross-section. In this work, the electron and hole mobility (μ) of LiIn1−xGaxSe2(x = 0, 0.25, 0.5, 0.75, 1) were studied by first-principles density functional theory (DFT) calculation, which demonstrated the electron mobility (μ e) of LiIn0.5Ga0.5Se2 is close to that of LiInSe2 while the hole mobility (μ h) is much improved. To further certify, both LiIn0.5Ga0.5Se2 and LiInSe2 crystals were grown under similar condition by vertical Bridgman method, exhibited comparable bandgap and bulk resistivity at room temperature. The charge transport behaviors were evaluated under 241[email protected] alpha particles. The full energy peak is clearly resolved in the pulse height spectra. The electron and hole mobility-lifetime products of LiIn0.5Ga0.5Se2 are 1.5×10−5 cm2/V and 6.9×10−5 cm2/V, respectively. The resulting μ e of LiIn0.5Ga0.5Se2 and LiInSe2 crystals are 270 cm2V−1s−1 and 180 cm2V−1s−1, respectively, fitted by time of flight (TOF) technique. In addition, the μ h of LiIn0.5Ga0.5Se2 is obtained with the value of 110 cm2V−1s−1, but the hole response is too weak to be resolved for LiInSe2.

Lévy Flights and Wavelets Analysis of Volcano-Seismic Data

In this work, we explore the use of Levy flight and wavelet techniques as a tool for investigating the statistical properties of the seismic signals generated during volcanic eruptions. Using two methodologies, we discuss the statistical characterization of the whole seismic signal, from days prior to the eruption to days after the eruption. We show that the seismic energy released can be modeled using the stochastic Levy flight model. The values of the Levy flight exponent parameters $$\alpha$$ were less than 2.0, indicating that the evolution of the released energy exhibits a long memory behavior. Furthermore, the wavelet techniques help to characterize the temporal evolution of the eruptive process. This observation is supported by our wavelet analysis, where we conclude that the proportions of total wavelet energy at lower levels of the eruption is high compared to the proportions at upper levels. The results from this study are expected to provide the basis for further analysis that might require a previous knowledge of the statistical behavior and parameters that characterize the seismic signals generated by these events.

Paenibacillus stellifer: a new cause of human infections

Introdução: Paenibacillus stellifer está amplamente distribuído na natureza, mas sua patogenicidade não foi relatada, desde que foi identificado pela primeira vez em 2003. Objetivos: Este trabalho objetivou identificar bacilos Gram-variáveis, isolados em casos de infecções relacionadas à assistência à saúde, no período de Setembro/2015 a Agosto/2016, em um hospital da região serrana do Rio de Janeiro, Brasil e avaliar o perfil de sensibilidade destes microrganismos a antibióticos comumente empregados na prática clínica. Métodos: Inicialmente, os microrganismos foram identificados a partir de testes bioquímicos convencionais e o resultado foi confirmado através da técnica de Matrix-Assisted Laser Desorption/Ionization — Time of Flight (MALDITOF). O teste de sensibilidade aos antimicrobianos foi realizado de acordo com as recomendações do Clinical and Laboratory Standards Institute. Resultados: Foram analisadas 105 amostras: 59 secreções de feridas cirúrgicas e 46 hemoculturas. Bacilos Gram-variáveis foram identificados em duas amostras de secreção de ferida cirúrgica (3,39%) e em duas hemoculturas (4,35%). Paenibacillus stellifer foi o microrganismo isolado nas quatro amostras e apresentou sensibilidade perante todas as drogas testadas. Conclusão: P. stellifer é um microrganismo de origem ambiental e não compõe a microbiota humana. De acordo com o conhecimento atual, esta é a primeira identificação de P. stellifer, como agente etiológico de infecções de ferida cirúrgica no mundo, e bacteremia no Brasil. Por fim, destaca-se o fato de que microrganismos normalmente encontrados no ambiente são capazes de causar infecções, quando presentes no ambiente hospitalar.

Implementation of tactical maneuvers with maneuver libraries

This study creates and combines the general maneuver libraries for fixed-wing aircraft to implement tactical maneuvers. First, the generalized maneuver libraries are established by analyzing the characteristics of tactical maneuvers required in battlefields. The 7th order polynomial is applied to both the creation of the maneuver libraries and the generation of the trajectories or flight paths for modal inputs. To track the desired trajectory, we design the Attitude Command Attitude Hold (ACAH) system and the Rate Command Rate Hold (RCRH) system using Model Following Controller (MFC). Moreover, the Line-of-Sight (LOS) guidance law is designed. In particular, the CONDUIT® is employed to optimize the gains so that the control systems meet the aircraft Handling Qualities (HQ) criteria. Finally, flight simulations are performed for the longitudinal loop, immelmann-turn, and climb-slalom-descent maneuvers to verify that tactical aggressive maneuvers are realizable via the combination of maneuver libraries. This study can contribute to the development of flight techniques for aircraft tactical maneuvers and to the revision of air force operational manuals.

The effects of temperature and frequency dispersion on sound speed in bulk poly (vinyl alcohol) poly (N-isopropylacrylamide) hydrogels caused by the phase transition

Bulk Poly (Vinyl Alcohol) (PVA) Poly (N-isopropyl acrylamide) (PNIPAm) hydrogel, one of the thermally responsive phase transitive hydrogels, is a versatile material due to its sharp volumetric phase transition and anomalous behaviors with facile tunability by thermal stimulation. At the lower critical solution temperature (LCST) of 33 °C, the hydrogels undergo a volumetric phase transition that causes drastic, non-monotonic change in the elastic modulus, viscosity, stiffness, and speed of sound. Here, we report the temperature and frequency dependence of the speed of sound in bulk PVA-PNIPAm hydrogel as measured by means of a planar resonant cavity. The linear response theory is applied for calculation of frequency dependent speed of sound. Comparisons find standard time of flight techniques underestimate the speed of sound by up to 6%, with variation in the frequency dependent speed of sound reaching as high as 200 m/s in the ultrasonic range of 0.2–0.8 MHz. The first characterization of frequency dependent speed of sound in PVA-PNIPAm hydrogel is addressed and delineated into its phase transition behaviors as connected to temperature. The findings can lead to better characterization of mechanical properties using ultrasonic spectroscopy, and higher resolution in ultrasonic imaging applications with dispersive media.

Fragmentation of pure nitromethane in the gas phase and a collision-free system at laser interactions of 532 nm, 355 nm, and 266 nm

High-resolution mass spectrometry using the time of flight (TOF) technique with a reflectron with multiphoton absorption was used to analyze the fragmentation pattern of nitromethane in a collision-free system. We used a radiation source with nanosecond laser pulses of 532 nm, 355 nm, and 266 nm wavelengths and a supersonic jet of nitromethane to produce positive fragment ions. The density power (irradiation) range was from 109 to 1010 W/cm2. The identification of 20 ions at a wavelength of 532 nm was obtained, whereas at 266 nm, more than 60 fragment ions were identified, as was the parent ion and many clusters. We associate these ionic fragments as a function of the intensity, energy, and pulse duration of the radiation source. The observation of radicals such as CH1,2,3, C2H1,2,3, C3H1,2,3, and CH3O, CHNO, higher mass molecules, and clusters is presented. The absence of the parent ion at 532 nm and 355 nm wavelengths demonstrates that the ladder switching mechanism elucidates the dissociation-ionization (DI) pathways of nitromethane. At 266 nm, the presence of the parent ion and the clusters are an indication of the functioning of the other model of fragmentation (ID). Due to the experimental characteristics, the numerous fragments seem to be a result of the interactions of the intensity of the electromagnetic radiation over nitromethane in the gas phase and their clusters.

Uncertainty evaluation and phase variation of ultrasonic interferometer manometer: A primary pressure and vacuum standard

The ultrasonic interferometer manometer (UIM) is an apex level primary pressure standard for Pascal realization established at National Physical Laboratory India (NPLI). The performance of UIM has been evaluated from time to time by participation in key comparisons, calibration and measurement capabilities (CMC) and publications in reputed international metrology journals. The pressure is measured using time of flight technique at 44 different frequencies in ultrasonic range and the phase measurement. The phase measurement combined with the time of flight measurement using the exact fractional algorithm provides highly accurate column length hence respective pressure values. The combined process helps in lowering the uncertainty in real experimental conditions. Recently, we have also changed UIM software from tbasic to window based program with the same algorithm which provides a column length measurement study. A detailed study was carried out for variation of fringe counts or oscillations with varying pressure. Experimental and theoretical calculation for both resolution and pressure dependent part has been carried out for uncertainties involves the physical parameters. The uncertainties in lower pressure range, i.e., between 1 Pa and 1000 Pa were varying equal or sometimes higher than the theoretical resolution value 0.0092 Pa (k = 2) because of environmental conditions like vibration, temperature, atmospheric pressure, and humidity whereas for higher pressure range, i.e., 1000 Pa to 130 kPa the uncertainties were either close or smaller than the pressure dependent theoretical uncertainty value, i.e. 7.2 × 10−6 of the reading.

A simulation study of a fan-beam time-of-flight fast-neutron tomography system

A fast neutron imaging system, consisting of a deuterium-tritium neutron generator, an associated alpha-particle detector and an arc-shaped array of individual neutron detectors is simulated for fan-beam fast neutron tomography purpose. In this system, the associated particle and time of flight techniques are used to separate transmission neutrons from scattered neutrons by electronically collimating and time tagging the source neutrons. To evaluate factors affecting the system’s spatial resolution and image quality, a series of simulations were performed with a GEANT4 based Monte Carlo program. The parameters include neutron detector resolution, system coincidence resolving time and reconstruction algorithm. The simulation results indicate that a reconstructed image resolution of about 2.1 mm can be obtained with an array of two hundred 4 mm resolution neutron detectors. With the aid of electronic collimation and time tagged based event filtering, the reconstructed image quality was significantly improved. Among iterative reconstruction algorithms tested, the Simultaneous Algebraic Reconstruction Technique-Total Variation algorithm showed better overall performance than others.

Realisation and Characterisation the BEC for 87Rb Atoms

The Bose-Einstein condensate (BEC) is created in a magnetic trap in the Quadrupole-Ioffe configuration (QUIC). This kind of trap combines an anti-Helmholtz quadrupole field with an offset field produced by a single coil perpendicular to the quadrupole field axis to suppress Majorana transitions. In the quadrupole trap evaporative cooling is performed by using radio frequency, reaching the phase transition to a BEC in the QUIC trap. By using Time of Flight (TOF) technique, the expansion velocity is measured with and which lead to temperature of and It is roughly around the recoil temperature.

Optimization of the flight technique in ski jumping: The influence of wind

Ski jumping performance is strongly affected by wind. Flight technique optimization for maximizing jump length is a highly complex motor-control task that also depends on the wind. Pontryagin's minimum principle was used in this study to gain a better understanding on how wind influences flight technique optimization. Optimum time courses of the angle of attack α of the skis and of the body-to-ski angle β were computed for seven realistic wind scenarios on the large hill and on the flying hill. The optimum values of α were smaller at headwind, and larger at tailwind when compared to the optimum time course at calm wind. The optimum values of β were the smallest possible ones at the given flight technique constraints, except for the last part of the flight. Optimum adjustments of α increased the jump lengths between 0 and 1.8 m on the large hill, and between 0 and 6.4 m on the flying hill. Maximum jump length increases were achieved at the highest headwind speed. Even larger jump length effects can be achieved by using smaller β-angles, which might be possible in headwind conditions, but this is associated with increased problems to keep the flight stable.

Neutron capture data for unstable nuclei – Astrophysical quests and experimental challenges

The abundances of the chemical elements heavier than iron can be attributed in about equal parts to the r and s processes, which are taking place in supernova explosions and during the He and C burning phases of stellar evolution, respectively. So far, quantitative studies of the r-process are out of reach, because it involves reactions on extremely short-lived neutron-rich nuclei. On the contrary, the situation for the s-process is far advanced, thanks to a comprehensive database of experimental (n,γ) cross sections for most isotopes along the reaction path from 12C to the Pb/Bi region. For the stable isotopes last gaps in the data are presently closed, but further studies are clearly needed to reach the required accuracy and to resolve remaining discrepancies. The quest for cross sections of unstable isotopes remains a persisting challenge though. In particular, nuclei which act as branching points are of prime interest, because they provide key information on the deep stellar interior. While the activation method is limited to a few exceptional branch-point nuclei, successful measurements via the time-of- flight technique are depending on intense pulsed neutron sources and elaborate methods for sample production. Current developments in Europe are providing promising perspectives in both areas.

Characteristics of Moyamoya Syndrome in Sickle-Cell Disease by Magnetic Resonance Angiography: An Adult-Cohort Study.

Background: Sickle cell disease (SCD) can be complicated by moyamoya syndrome. Brain magnetic resonance angiography (MRA) is a non-invasive method to diagnose this syndrome and, steno-occlusion and moyamoya vessels (MMV) scores have been proposed to evaluate its severity. Previous studies of SCD moyamoya syndrome did not evaluate the severity according to MRA scores. The objective was to assess the characteristics of moyamoya syndrome in an adult cohort of SCD using these MRA scores.Methods: Twenty-five SCD patients with moyamoya syndrome were included using MRA with 3D time of flight technique. We evaluate steno-occlusion score for each hemisphere (range 0–10) from: steno-occlusion severity of internal carotid (ICA) (0–3), anterior cerebral (ACA) (0–3), middle cerebral (MCA) (0–2), and posterior cerebral (PCA) (0–2) arteries. MMV score for each hemisphere (range 0–5) depended from 5 MMV areas: (1) anterior communicating artery (2) basal ganglia (3) ICA/MCA (4) posterior communicating artery/PCA (5) basilar artery.Results: Eight patients (32%) showed unilateral moyamoya syndrome. ICA steno-occlusion was involved in 22 patients (88%), MCA in 23 patients (92%), ACA in 9 patients (36%), and PCA in 3 patients (12%). MMV involved ACoA area in 10 patients (40%), basal ganglia in 13 patients (52%), PCoA/PCA in 10 patients (40%), MCA/ICA in 7 patients (28%), and BA in 1 patient (4%). Steno-occlusion and MMV mean hemisphere scores were 3.4/10 (± 1.42) and 1.6/5 (± 0.71), respectively.Conclusion: Frequent unilateral moyamoya syndrome, uncommon PCA involvement and, moderate steno-occlusion and MMV scores seem to be features of SCD moyamoya syndrome. In future studies, MRA scores could be collected to assess the follow-up in these patients.