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Experimental analyses of synthetic jet control (SJC) effects on aerodynamic characteristics of rotor in steady state and in hover were conducted. To ensure the structural strength of rotor and enough interior space for holding the synthetic jet actuators (SJAs), a particular blade with a frame-covering structure was designed and processed, and the experiment was conducted with low free stream velocities and rotor rotation speeds. There were three test conditions. In steady state, there were three free stream velocities (10m/s, 15m/s and 20m/s). In hover state, the rotor was worked with two rotation speeds of 180RPM and 240RPM. In forward flight, the rotor was worked with a rotation speed of 180RPM and a free stream velocity of 7.5m/s. To measure the synthetic jet control effect on rotor in stall, the range of collective pitch was set from 10° to 28° in steady state. The aerodynamic forces and sectional velocity field were measured by using the six-component balance and the Particle Image Velocimetry (PIV) system in the wind tunnel. Flow control effects on the blade based on the synthetic jets (SJ) were experimentally investigated with different jet parameters, such as jet locations, jet angles, and jet velocities. In steady state, the jet closer to the leading edge, and the jet angle of 90° had more advantages in improving the aerodynamic characteristics. Furthermore, the aerodynamic forces and sectional velocity field measurement of rotor in hover were conducted, it showed that SJAs could increase flow velocity at the upper surface, which led to lower upper surface pressure. As a result, the normal forces of rotor with two rotation speeds were increased significantly. These results indicated that the synthetic jet has a capability of increasing the normal force and delaying or preventing the stall of rotor.
Orthocoelium streptocoelium is a common paramphistome species parasitizing the rumen and/or reticulum of small ruminants, leading to significant losses. This study first determined the complete mitochondrial (mt) genome of O. streptocoelium. The complete mt genome of O. streptocoelium was amplified, sequenced, assembled, analysed and then compared with those of other digeneans. The entire mt genome of O. streptocoelium is 13,800 bp in length, which is smaller than those of other digeneans except for Opisthorchis viverrini. This mt genome contains 12 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and two non-coding regions. The arrangement of the O. streptocoelium mt genome is the same as those of other digeneans except for Schistosoma haematobium and Schistosoma spindale. Phylogenetic analyses based on concatenated amino acid sequences of the 12 protein-coding genes representing 16 digeneans were conducted to assess the relationship of O. streptocoelium with other digeneans. The result indicated that O. streptocoelium is closely related to Paramphistomum cervi and Fischoederius elongates, which is in accordance with their relationships by taxonomy. This complete mt genome of O. streptocoelium enriched the mitochondrial genome data of paramphistomes and provided important molecular markers for diagnostics and studies of population variation, epidemiology, ecology and evolution of O. streptocoelium and other digeneans.
In the experiments reported here, we used the female ladybird Coccinella septempunctata L. as a model to identify diapause-associated proteins using proteomics technology. Our results indicated that protein expression patterns of diapausing and nondiapausing individuals were highly differentiated. A total of 58 spots showed significant differences in abundance (Ratio > 2 and P < 0.05) according to two-dimensional electrophoresis and GE Image Scanner III analysis. Sixteen protein spots were further investigated using mass spectrometry. Eight proteins were characterized, including chaperones and proteins involved in glucose metabolism, lipid metabolism, and the tricarboxylic acid cycle. Among these proteins, five proteins were upregulated in diapausing female adults, including a chaperone (Symbionin symL), malate dehydrogenase (putative), two proteins linked to lipid metabolism (unknown and conserved hypothetical protein) and phosphoglyceromutase (partial). By contrast, isocitrate dehydrogenase (RH49423p), fumarylacetoacetate hydrolase (AGAP001942-PA), and a putative medium chain acyl-CoA dehydrogenase were downregulated. These results contribute to the understanding of diapause mechanisms of the ladybird C. septempunctata and may suggest methods for improving the application of this natural enemy insect.
Travelling internationally to acquire medical treatments otherwise unavailable or inaccessible in one’s home country is not a novel concept. Conventionally, such medical travel largely entailed patients from developed countries or wealthy patients from the developing world seeking care in Western facilities like the Mayo Clinic in the U.S. and myriad private clinics along Harley Street in London, England. What is different about the topical phenomenon known as “medical tourism” is the growing trend of health services export in the opposite direction. The number of patients travelling from the developed world to low- and middle-income countries (LMICs) for treatments has ballooned in recent years, primarily driven by difficulties with accessing affordable care at home. According to a liberal estimate by the Deloitte Center for Health Solutions, the number of Americans travelling abroad for care rose from 750,000 in 2007 to 1.6 million in 2012. On the flip side, Thailand reportedly treated a total of 1.3 million foreign nationals in 2007, which represented a 16% leap from 2001.
The Ultra-Fast Flash Observatory (UFFO) is a space observatory for optical follow-ups of
gamma ray bursts (GRBs), aiming to explore the first 60 seconds of GRBs optical emission.
UFFO is utilized to catch early optical emissions from GRBs within few sec after trigger
using a Gimbal mirror which redirects the optical path rather than slewing entire
spacecraft. We have developed a 15 cm two-axis Gimbal mirror stage for the UFFO-Pathfinder
which is going to be on board the Lomonosov satellite which is to be launched in 2013. The
stage is designed for fast and accurate motion with given budgets of 3 kg of mass and 3
Watt of power. By employing stepping motors, the slewing mirror can rotate faster than 15
deg/sec so that objects in the UFFO coverage (60 deg × 60 deg) can be targeted in
~1 sec. The obtained targeting resolution is better 2 arcmin using a close-loop
control with high precision rotary encoder. In this presentation, we will discuss details
of design, manufacturing, space qualification tests, as well as performance tests.
Recent theoretical progress in understanding the nonlinear optical response of noble metal nanocomposite materials with an enhanced third-order nonlinear susceptibility was reviewed. The enhanced third-order nonlinear susceptibility results from the surface plasmon resonance (SPR) of noble metal nanoparticles. And then the enhancement strongly depends on irradiation light wavelength, concentration and surrounding medium of noble metal particles. Furthermore, their applications as optical switchers with ultrashort time response and optical limiters of intense laser radiation were also reviewed. Moreover, the enhancement mechanism of third-order nonlinear susceptibility, and physical process was further discussed in detail, which was very important for further improvement of third-order nonlinear susceptibility and application on optical switchers and optical limiters for noble metal nanoparticles.
The unipolar resisitive switching properties of MOCVD deposited NiO in Ni/NiO/TiN stacks is reported. The switching quality is defined as function of RESET current and Roff/Ron ratio, and the importance of the Forming current and voltage on these parameters is discussed. The effect of structural stack variations as NiO thickness, Ti doping, and TiN thickness on the switching behavior of NiO is explained by the effect on the forming current and voltage conditions, and on Joule heating dissipation. Thinner NiO films, Ti doping, as well as thicker top electrode improve the switching quality by decreasing the RESET current and increasing the Roff/Ron ratio.
We report on the formation of ultrafine-grained Ti66Nb13Cu8Ni6.8Al6.2 composites with in situ precipitated micrometer-sized β-Ti(Nb) phase by spark plasma sintering with crystallization. Microstructure analysis indicated that all alloys consisted of soft (Cu, Ni)Ti2 regions surrounded by hard β-Ti(Nb) regions but displayed different microstructures. The alloys exhibited high fracture strength of more than 2200 MPa and remarkable plasticity of ∼25%. The results provided a promising method for fabricating large-sized bulk composites with excellent mechanical properties by powder metallurgy.
Quasi-monoenergetic electron beams of energies 12 MeV to over 200 MeV are generated from both nitrogen and helium gas targets with 7TW laser pulses. Typically nitrogen gas interactions lead to electron bunches in the range of 12 to 50 MeV varying from shot to shot. Helium gas leads to higher energy electron bunches from 25 to 100 MeV. Occasionally exceptionally high energy bunches of electrons up to 200 MeV are observed from nitrogen and helium. Initial full two-dimensional simulations indicate the production of 20–30 MeV electron energy bunches for the typical interaction conditions as the electrons are injected from wave breaking in the plasma wake behind the laser pulse and injected into the strong electric field gradient propagating with the optical pulse. This is consistent with the experimental observations from the majority of shots. Pulse compression during propagation in the high density plasma does not allow the threshold conditions for the full bubble regime to be reached. However, the electric acceleration field in the wakefield cavity is still sufficient to lead to the formation of a bunch of electrons with an energy peak in the range of 20 to 30 MeV. In order to explain the occasional high energy shots most likely a lower density channel created by the laser prepulse may occasionally form a natural low density electron guide channel giving ideal conditions for acceleration over much longer lengths leading to the high energies observed.
Amorphous Ti66Nb13Cu8Ni6.8Al6.2 alloy powders with different tungsten carbide (WC) contents were synthesized by mechanical alloying. Outstanding differences in particle size, thermal stability, glass-forming ability, and phase evolution are found for the synthesized Ti-based glassy powders with different WC contents. This is attributed to the fact that the WC was partially alloyed into the glassy matrix and the matrix element Ti was also partially alloyed into the WC particles. The obtained glassy powders exhibit a wide supercooled liquid region above 64 K. Meanwhile, the main crystalline phase is the ductile β-Ti with a high volume fraction in the crystallized alloy powders. These two aspects offer the possibility of easily preparing a plasticity-enhanced bulk composite in the supercooled liquid region by powder metallurgy, which couples the nanosized WC particles with in situ precipitated ductile β-Ti phase.
Amorphization of metallic titanium by ball milling was presented. With the introduction of continuous pickup of impurities, hexagonally close-packed (hcp) titanium transformed gradually into an amorphous phase without experiencing any intermediate stage of forming a detectable metastable compound phase. The crystallization temperature of the obtained Ti metal glassy phase is about 640 K. The total concentration of the impurities (oxygen, nitrogen, iron, etc.) in the final product of the milled powders that was obtained after 60 h of milling was 10.85 at.%. The amorphization of metallic titanium may account for the combined effects of the pickup oxygen impurity in small amount and the Gibbs–Thompson effect.
Solar radio fine structures (FSs) may be as an important diagnostics stool to draw the evolution map of the flare loop in the initial phase of solar flares. Also, it may be an important signature of the initial phase of CMEs. Here we analyzed a series of solar radio bursts with drift pulsation structures (DPS) and FSs during the former part of the 23rd solar activity cycle. Found they were associated with CMEs, and got some important statistic conclusions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html
Polymorphous Si nanowires (SiNWS) have been successfully synthesized on Si wafer by plasma enhanced chemical vapor deposition (PECVD) at 440°C, using silane as the Si source and Au as the catalyst. To grow the polymorphous SiNWS preannealing the Si substrate with Au film at 1100 °C is needed. The diameters of Si nanowires range from 15 to 100 nm. The structure, morphology and chemical composition of the SiNWS have been characterized by high resolution x-ray diffraction, scanning electron microscopy, transmission electron microscopy, as well as energy dispersive x-ray spectroscopy. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique.
Low temperature (50-400°C) and low pressure (10-300 mTorr) processing conditions for remote H-plasma cleaning of Si(100) substrates were investigated. After plasma exposure, ordered surfaces were obtained which displayed 2×1, 3×l and lxI LEED diffraction patterns. The surface phases following the H-plasma clean were dependent on temperature and pressure. The electronic states of the surfaces were explored with angle resolved uv-photoemission spectroscopy (ARUPS) and states due to Si-H bonding were identified. The atomic interactions at the surface were modeled in terms of several processes including Eley-Rideal abstraction, thermally activated desorption and a physisorbed weakly bound state. The kinetic model was able to describe the transitions observed in the processing results. Suitability of the cleaning process for low temperature epitaxy was demonstrated by low temperature MBE epi-growth on an H-terminated 2×1 surface. The initial oxide formation on the H-terminated surfaces were studied by ARUPS.
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