Natural Characteristics Analysis for the Spacecraft Equipped with Constructed Cantilever Solar Panels

The power series polynomial constraining method is proposed in this paper. The dynamical model of the cantilever plate can be established by applying the constraint, which is different from the traditional polynomial. Firstly, the characteristic orthogonal polynomial was used to describe the displacement field of the rectangular plate of which all edges are free. Then the four-sided free plate was equivalent to cantilever plate by power series multiplier constraint method. The characteristic equation of the constructed cantilever plate was obtained by the Rayleigh–Ritz method. Natural frequencies and modal shapes of the plate were obtained by solving the characteristic equation. Next, the proposed method was adopted to establish dynamical model of a pair of solar panels clamped on the central platform symmetrically. The convergence of the proposed method was verified by comparing the calculated results of the cantilever plate with that of the finite element software ANSYS 15.0. The optimum order the power series polynomial was obtained by comparing different results. The analysis of the dynamical characteristics of the cantilever plate and the spacecraft demonstrates the validation of the proposed method. This method can provide a new idea for the plate with local edge constrained

Trichlorido[4-methoxy-2,6-bis(2-pyrimidin-2-yl-κN)phenyl-κC1]platinum(IV) acetonitrile monosolvate

In the title complex, [Pt(C15H11N4O)Cl3]·CH3CN, the PtIV ion adopts a distorted octahedral coordination geometry defined by a tridentate cyclometalated NCN ligand and three Cl atoms. In the crystal, individual molecules are aggregated into a three-dimensional network by C—H...Cl hydrogen-bonding interactions and π–π stacking interactions between the tridentate ligands, the shortest ring centroid–centroid distance being 3.613 Å

2-[3-Methoxy-5-(pyrimidin-2-yl)phenyl]pyrimidine

The title compound, C15H12N4O, was synthesized by a standard Suzuki cross-coupling reaction. The terminal pyrimidine rings are rotated at dihedral angles of 12.06 (4) and −13.13 (4)° with respect to the central benzene ring. In the crystal, the molecules are connected by two kinds of C—H...N hydrogen bonds, forming zigzag chains along the c axis. Weak π–π interactions between the benzene and one of the pyrimidine rings are also found and stack the molecules along the b axis [centroid–centroid distance = 4.112 (3) Å]

Ground Stereo Vision-based Navigation for Autonomous Take-off and Landing of UAVs: A Chan-Vese Model Approach

This article aims at flying target detection and localization of a fixed-wing unmanned aerial vehicle (UAV) autonomous take-off and landing within Global Navigation Satellite System (GNSS)-denied environments. A Chan-Vese model–based approach is proposed and developed for ground stereo vision detection. Extended Kalman Filter (EKF) is fused into state estimation to reduce the localization inaccuracy caused by measurement errors of object detection and Pan-Tilt unit (PTU) attitudes. Furthermore, the region-of-interest (ROI) setting up is conducted to improve the real-time capability. The present work contributes to real-time, accurate and robust features, compared with our previous works. Both offline and online experimental results validate the effectiveness and better performances of the proposed method against the traditional triangulation-based localization algorithm.Published versio

The effect of renal denervation on resistant hypertension: Meta-analysis of randomized controlled clinical trials

<p><i>Background</i>: This meta-analysis was conducted to evaluate the efficiency of renal denervation (RDN) on resistant hypertension. <i>Methods</i>: PubMed, EMBASE, and the Cochrane Central database were searched for eligible randomized controlled clinical trials (RCTs). Changes from the baseline of the office blood pressure and the 24-h ambulatory blood pressure were extracted. <i>Results</i>: Nine RCTs were included. RDN reduced the mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) by −8.23 mm Hg (95%CI: −16.86, 0.39) and −3.77 mm Hg (95%CI: −7.21, −0.32), respectively, compared with the control. In the population with a baseline SBP more than 170 mm Hg, the RDN reduced SBP by −17.77 mm Hg (95%CI: −33.73, −1.82) and DBP by −7.51 mm Hg (95%CI: −12.58, −2.44). In the subgroup with no medication adjustment, the RDN reduced SBP by −15.56 mm Hg (95%CI: −26.33, −4.80) and DBP by −6.89 mm Hg (95%CI: −9.99, −3.79). The proportion of patients with SBP decrease of 10 mm Hg or more and the controlled office BP were not different between two groups. RDN reduced 24-h mean SBP and DBP by −3.34 mm Hg (95%CI: −5.30, −1.38) and −1.56 mm Hg (95%CI: −2.71, −0.41), respectively. The SBPs in the subgroups with higher baseline SBP and with no medication adjustment were significantly decreased after the HTN-3 was omitted. <i>Conclusion</i>: Radiofrequency RDN in a randomized manner did not have superiority compared with medical treatment at 6-month follow-up in general population. Current evidence provides insufficient evidence to support the use of such RDN strategy in the treatment of resistant hypertension. The result could not be used to extrapolate other strategies’ effect.</p

Size-Selective Recognition by a Tubular Assembly of Phenylene–Pyrimidinylene Alternated Macrocycle through Hydrogen-Bonding Interactions

Study of artificial tubular assemblies as a useful host scaffold for size-selective recognition and release of guest molecules is an important subject in host–guest chemistry. We describe well-defined self-assembled nanotubes (<b>NT</b>_<b>6mer</b>) formed from π-conjugated <i>m</i>-phenylene–pyrimidinylene alternated macrocycle <b>1</b>_<b>6mer</b> that exhibit size-selective recognition toward a specific aromatic acid. In a series of guest molecules, a size-matched trimesic acid (<b>G3</b>) gives inclusion complexes (<b>NT</b>_<b>6mer</b>⊃<b>G3</b>) in dichloromethane resulting in an enhanced and red-shifted fluorescence. ¹H nuclear magnetic resonance (NMR) titration experiments indicated that the complex was formed in a 1:1 molar ratio. Density functional theory (DFT) calculations and the binding constant value (<i>K</i> = 1.499 × 10⁵ M^–1) of <b>NT</b>_<b>6mer</b> with <b>G3</b> suggested that the complex involved triple hydrogen-bonding interactions. The encapsulated guest <b>G3</b> molecules can be readily released from the tubular channel through the dissociation of hydrogen bonding by the addition of a polar solvent such as dimethylsulfoxide (DMSO). In contrast, <b>1</b>_<b>6mer</b> could not form self-assembled nanotubes in CHCl₃ or tetrahydrofuran (THF) solution, leading to weak or no size-selective recognizability, respectively

Photoreversible [2] Catenane via the Host–Guest Interactions between a Palladium Metallacycle and β‑Cyclodextrin

We report the efficient preparation of an A₂D₂ (A = acceptor and D = donor) metallacycle <b>2</b> = [(en)₂Pd₂(<b>1</b>)₂]­(NO₃)₄, using the coordination driven self-assembly of <i>trans</i>-azobenzene based bispyridyl ligand <b>1</b> and (en)­Pd­(NO₃)₂ (en = ethylenediamine). In the metallacycle, the <i>trans</i>-azobenzene units serve both as a structural element and as sites for subsequent host–guest chemistry with β-cyclodextrin, leading to the formation of a [2] catenane <b>3</b>. This catenation process is reversible and can be switched off and on in a photocontrollable manner via the <i>trans</i>–<i>cis</i> isomerization of the azobenzene units