Research of the active reflector antenna using laser angle metrology system

Active reflector is one of the key technologies for constructing large telescopes, especially for the millimeter/sub-millimeter radio telescopes. This article introduces a new efficient laser angle metrology system for the active reflector antenna of the large radio telescopes, with a plenty of active reflector experiments mainly about the detecting precisions and the maintaining of the surface shape in real time, on the 65-meter radio telescope prototype constructed by Nanjing Institute of Astronomical Optics and Technology (NIAOT). The test results indicate that the accuracy of the surface shape segmenting and maintaining is up to micron dimension, and the time-response can be of the order of minutes. Therefore, it is proved to be workable for the sub-millimeter radio telescopes.Comment: 10 pages, 15 figure

Compact Dual-Band Planar Inverted-e-Shaped Antenna Using Defected Ground Structure

This paper presents a novel dual-band planar inverted-e-shaped antenna (PIEA) using defected ground structure (DGS) for Bluetooth and wireless local area network (WLAN) applications. The PIEA can reduce electromagnetic interferences (EMIs) and it is constructed on a compact printed circuit board (PCB) size of 10 × 5 × 4 mm3. Experimental results indicate that the antenna with a compact meandered slit can improve the operating impedance matching and bandwidths at 2.4 and 5.5 GHz. The measured power gains at 2.4 and 5.5 GHz band are 1.99 and 3.71 dBi; antenna efficiencies are about 49.33% and 55.23%, respectively. Finally, the good performances of the proposed antenna can highly promote for mobile device applications

5-Amino-7-(3-chloro­phen­yl)-3,7-di­hydro-2H-thieno[3,2-b]pyran-6-carbo­nitrile 1,1-dioxide

The title compound, C14H11ClN2O3S, with fused thiophene and pyran rings, was synthesized via the condensation of dihydro­thio­phen-3(2H)-one 1,1-dioxide and 2-(3-chloro­benz­yl­idene)malononitrile catalysed by triethyl­amine in ethanol. The thio­phene ring adopts an envelope conformation and the pyran ring is planar (r.m.s. deviation = 0.0067 Å). The dihedral angle between the pyran and phenyl rings is 80.8 (1)°. The crystal packing is stabilized by inter­molecular N—H⋯N and N—H⋯O hydrogen bonds in which the cyano N and sulphone O atoms, respectively, acting as acceptors

Combined effects of permeability and fluid saturation on seismic wave dispersion and attenuation in partially-saturated sandstone

Knowledge of dispersion and attenuation is essential for better reservoir characterization and hydrocarbon identification. However, limited by reliable laboratory data at seismic frequency bands, the roles of rock and fluid properties in inducing dispersion and attenuation are still poorly understood. Here we perform a series of laboratory measurements on Bentheimer and Bandera sandstone under both vacuum-dry and partially water-saturated conditions at frequencies ranging from 2 to 600 Hz. At vacuum-dry conditions, the bulk dispersion and attenuation in Bandera sandstone with more clay contents are distinctly larger than those in Bentheimer sandstone, suggesting clay contents might contribute to the inelasticity of the rock frame. The partially water-saturated results show the combined effects of rock permeability and fluid saturation on bulk dispersion and attenuation. Even a few percent of gas can substantially dominate the pore-fluid relaxation by providing a quick and short communication path for pore pressure gradients. The consequent bulk dispersion and attenuation are negligible. Only as the samples are approaching fully water-saturated conditions, rock permeability begins to play an essential role in the pore-fluid relaxation. For Bandera sandstone with lower permeability, a partially relaxed status of pore fluids is achieved when the gas saturation is lower than 5%, accompanied by significant attenuation and dispersion.Cited as: Wei, Q., Wang, Y., Han, D., Sun, M., Huang, Q. Combined effects of permeability and fluid saturation on seismic wave dispersion and attenuation in partially-saturated sandstone. Advances in Geo-Energy Research, 2021, 5(2): 181-190, doi: 10.46690/ager.2021.02.0

Meta-analysis of clinical randomized controlled trials comparing ReZOOM with ReSTOR multifocal intraocular lenses in cataract surgery

AIM: To systematic review the effectiveness of refractive multifocal intraocular lens(MIOL)ReZOOM <i>vs</i> diffractive MIOL ReSTOR in the treatment of cataract.<p>METHODS: Randomized controlled trials comparing refractive MIOL ReZOOM with diffractive MIOL ReSTOR were identified by searching CENTRAL, MEDLINE, EMbase, WANFANG MED ONLINE, CMJD, SinoMed, and CNKI. Related journals also were hand-searched. Methodological quality of randomized controlled trials(RCTs)was evaluated by simple evaluate method that recommended by the Cochrane Collaboration. Data extracted by two reviewers with designed extraction form. RevMan software(release 5.2)was used for data management and analysis.<p>RESULTS:A total of 7 trials(846 eyes)were included for systematic review. Subgroup analyses were used according to different model comparison of ReSTOR MIOL. The results showed a significant difference in the mean of the best distance corrected intermediate visual acuity(BDCIVA)in the ReZOOM MIOL group with WMD= -0.11, 95% <i>CI</i>(-0.16, -0.06)(<i>P</i><0.0001). It showed a significantly difference in the mean of the uncorrected near visual acuity(UCNVA), complete spectacle independent rate, halo rate and glare rate in the ReSTOR MIOL group with WMD= 0.09, 95% <i>CI</i>(0.05, 0.14)(<i>P</i><0.00001), WMD= 2.62, 95%<i>CI</i>(1.76, 3.91)(<i>P</i><0.00001), WMD=1.35, 95% <i>CI</i>(1.15, 1.60)(<i>P</i>=0.0004)and WMD= 1.29, 95% <i>CI</i>(1.09, 1.53)(<i>P</i>=0.003). There was no significant difference between the two groups in the mean of the uncorrected distance visual acuity(UCDVA), the uncorrected intermediate visual acuity(UCIVA), the best corrected distance visual acuity(BCDVA)and the best distance corrected near visual acuity(BDCNVA)with WMD -0.03, 95% <i>CI</i>(-0.06, 0.01)(<i>P</i>=0.15), WMD= -0.04, 95% <i>CI</i>(-0.09, 0.01)(<i>P</i>=0.10), WMD= -0.01, 95%<i>CI</i>(-0.04, 0.02)(<i>P</i>=0.55)and WMD= 0.06, 95% <i>CI</i>(-0.06, 0.17)(<i>P</i>=0.32). <p>CONCLUSION: Patients implanted with ReZOOM MIOL can provide better BDCIVA; patients implanted with ReSTOR MIOL show better UCNVA, are less likely to appear light halo, glare and other visual adverse reactions; correction in spectacles cases, patients implanted with ReZOOM or ReSTOR MIOL have considerable performances in the far and near visual acuity

Ethyl 7-(4-bromo­phen­yl)-5-trifluoro­methyl-4,7-dihydro­tetra­zolo[1,5-a]pyrimidine-6-carboxyl­ate

In the title compound, C14H11BrF3N5O2, the pyrimidine ring adopts a flattened envelope conformation with sp 3-hybridized carbon as the flap [deviation = 0.177 (3) Å]. The dihedral angle between tetra­zole and bromo­phenyl rings is 84.3 (1)°. In the crystal, mol­ecules are linked into centrosymmetric dimers by pairs of N—H⋯N hydrogen bonds

Global Stability of a Variation Epidemic Spreading Model on Complex Networks

Epidemic spreading on networks becomes a hot issue of nonlinear systems, which has attracted many researchers’ attention in recent years. A novel epidemic spreading model with variant factors in complex networks is proposed and investigated in this paper. One main feature of this model is that virus variation is investigated in the process of epidemic dynamical spreading. The global dynamics of this model involving an endemic equilibrium and a disease-free equilibrium are, respectively, discussed. Some sufficient conditions are given for the existence of the endemic equilibrium. In addition, the global asymptotic stability problems of the disease-free equilibrium and the endemic equilibrium are also investigated by the Routh-Hurwitz stability criterion and Lyapunov stability criterion. And the uniform persistence condition of the new system is studied. Finally, numerical simulations are provided to illustrate obtained theoretical results