Investigative study on the development of a green UWB antenna

Copyright @ 2010 ISA

Receptive Field Block Net for Accurate and Fast Object Detection

Current top-performing object detectors depend on deep CNN backbones, such as ResNet-101 and Inception, benefiting from their powerful feature representations but suffering from high computational costs. Conversely, some lightweight model based detectors fulfil real time processing, while their accuracies are often criticized. In this paper, we explore an alternative to build a fast and accurate detector by strengthening lightweight features using a hand-crafted mechanism. Inspired by the structure of Receptive Fields (RFs) in human visual systems, we propose a novel RF Block (RFB) module, which takes the relationship between the size and eccentricity of RFs into account, to enhance the feature discriminability and robustness. We further assemble RFB to the top of SSD, constructing the RFB Net detector. To evaluate its effectiveness, experiments are conducted on two major benchmarks and the results show that RFB Net is able to reach the performance of advanced very deep detectors while keeping the real-time speed. Code is available at https://github.com/ruinmessi/RFBNet.Comment: Accepted by ECCV 201

1-Benzoyl-3,3-dibutyl­thio­urea

The title mol­ecule, C16H24N2OS, is twisted about the central N(H)—C bond with a C—N(H)—C—N torsion angle of −62.67 (15)°. The carbonyl group is twisted out of the plane of the benzene ring, forming a C—C—C=O torsion angle of −25.06 (17)°. In the crystal, mol­ecules related by centres of symmetry are linked by pairs of inter­molecular N—H⋯S hydrogen bonds, forming eight-membered {⋯HNCS}2 synthons. These are further connected by weak via C—H⋯O contacts, forming a two-dimensional array in the bc plane

[meso-5,10,15,20-Tetra­kis(5-bromo­thio­phen-2-yl)porphyrinato-κ4 N,N′,N′′,N′′′]nickel(II)

The NiII atom in the title porphyrin complex, [Ni(C36H16Br4N4S4)], is in a square-planar geometry defined by four pyrrole N atoms. There is considerable buckling in the porphyrin ring with the dihedral angles between the N4 donor set and the pyrrole rings being in the range 17.0 (3)–18.8 (3)°. Each of the six-membered chelate rings is twisted about an Ni—N bond and the dihedral angles between diagonally opposite chelate rings are 13.08 (15) and 13.45 (11)°; each pair of rings is orientated in opposite directions. The bromo­thienyl rings are twisted out of the plane of the central N4 core with dihedral angles in the range 51.7 (2)–74.65 (19)°. Supra­molecular chains along [001] are formed through C—H⋯Br inter­actions in the crystal packing. Three of the four bromo­thienyl units are disordered over two coplanar positions of opposite orientation with the major components being in 0.691 (3), 0.738 (3) and 0.929 (9) fractions

3-(4-Bromo­phen­yl)-1-phenyl-1H-pyrazole-4-carbaldehyde

In the title compound, C16H11BrN2O, the phenyl and chloro­benzene rings are twisted out of the mean plane of the pyrazole ring, forming dihedral angles of 13.70 (10) and 36.48 (10)°, respectively. The carbaldehyde group is also twisted out of the pyrazole plane [the C—C—C—O torsion angle is 7.9 (3)°]. A helical supra­molecular chain along the b axis and mediated by C—H⋯O inter­actions is the most prominent feature of the crystal packing

1-Benzoyl-3,3-bis­(propan-2-yl)thio­urea

Two independent thio­urea derivatives comprise the asymmetric unit of the title compound, C14H20N2OS. The major difference between the mol­ecules relates to a twist in the relative orientation of the benzene rings [torsion angles = 4.5 (2) and −19.9 (2)° for the two independent mol­ecules]. The thio­carbonyl and carbonyl groups lie to opposite sides of the mol­ecule as there are twists about the central N—S bond [torsion angles = 83.90 (15) and 81.77 (15)°]. Supra­molecular chains extending parallel to [101] with a stepped topology and mediated by N—H⋯O hydrogen bonding feature in the crystal structure. C—H⋯O and C—H⋯π inter­actions are also present

N,N′-Bis[(E)-(3-methyl-2-thienyl)methyl­idene]ethane-1,2-diamine

Two independent half-mol­ecules, each being completed by inversion symmetry, comprise the asymmetric unit of the title compound, C14H16N2S2. The major difference between the mol­ecules is found in the central C—C bond [the C—N—C—C torsion angles are 114.66 (18) and 128.94 (18)° in the two mol­ecules]. The thio­phene and imine groups are almost co-planar in each case [S—C—C—N torsion angles = −6.9 (2) and −3.6 (2)°]. In the crystal, the mol­ecules aggregate into supra­molecular chains via C—H⋯π inter­actions

N,N′-Bis[(E)-(5-chloro-2-thienyl)methyl­idene]ethane-1,2-diamine

The full mol­ecule of the title compound, C12H10Cl2N2S2, is generated by the application of a centre of inversion. The thio­phene and imine residues are co-planar [the N—C—C—S torsion angle is −2.5 (4)°] and the conformation about the imine bond [1.268 (4) Å] is E. Supra­molecular arrays are formed in the bc plane via C—Cl⋯π inter­actions and these stack along the a axis

Dicyclo­hexyl­ammonium thio­cyanate: monoclinic polymorph

The title salt, C12H24N+·NCS−, represents a monoclinic polymorph of the previously reported ortho­rhom­bic form [Khawar Rauf et al. (2008 ▶). Acta Cryst. E64, o366]. Two independent formula units comprise the asymmetric unit with the major difference in their mol­ecular structures relating to the relative dispositions of the cyclo­hexyl rings [dihedral angles = 79.88 (6) and 67.72 (5)°]. Further, the independent anions form distinctive patterns of hydrogen-bonding inter­actions, i.e. 2 × N—H⋯N versus N—H⋯N and N—H⋯S. The resulting supra­molecular architecture is a supra­molecular chain along the c axis based on a square-wave topology

Probing 5f-state configurations in URu2Si2 with U L3-edge resonant x-ray emission spectroscopy

Resonant x-ray emission spectroscopy (RXES) was employed at the U L3 absorption edge and the La1 emission line to explore the 5f occupancy, nf, and the degree of 5f orbital delocalization in the hidden order compound URu2Si2. By comparing to suitable reference materials such as UF4, UCd11, and alpha-U, we conclude that the 5f orbital in URu2Si2 is at least partially delocalized with nf = 2.87 +/- 0.08, and does not change with temperature down to 10 K within the estimated error. These results place further constraints on theoretical explanations of the hidden order, especially those requiring a localized f2 ground state.Comment: 11 pages,7 figure