catena-Poly[[bis­(nitrato-κ2 O,O′)cobalt(II)]-μ-4,4′-bis­(pyrazol-1-ylmeth­yl)biphenyl-κ2 N 2:N 2′]

In the title compound, [Co(NO3)2(C20H18N4)]n, the CoII atom lies on a crystallographic twofold axis and the coordination geometry can be considered as a slightly distorted tetra­hedron defined by two O atoms from two nitrate groups and two N atoms from two ligand mol­ecules. A distorted octa­hedron may be assumed when two of the symmetry-related nitrate O atoms with Co—O distances of 2.3449 (19) Å are added to the coordination environment. Another twofold axis, passing through the middle of the biphenyl bonds, is observed in the crystal structure. A chain is built up by the ligands linking the CoII ions along [101]

1-(4-tert-Butyl­benz­yl)-3-phenyl-1H-pyrazole-5-carboxylic acid

In the title compound, C21H22N2O2, the mean plane of the pyrazole ring makes dihedral angles of 18.80 (12) and 77.13 (5)°, respectively, with the mean planes of the phenyl and tert-butyl­benzyl rings. The carboxylate group is inclined at 8.51 (14)° with respect to the pyrazole ring. The crystal structure displays inter­molecular O—H⋯O hydrogen bonding, generating centrosymmetric dimers

Relaxation Behavior of Residual Stress on Deck-to-Rib Welded Joints by Fatigue Loading in an Orthotropic Bridge Deck

To accurately evaluate the influence of the actual tension and compression state and stress ratio at the deck-to-rib welding seam position on the fatigue life of a bridge deck, this paper establishes a coupled stress analysis model that considers the welding residual stress and vehicle stress. Taking the Jiangyin Bridge as an example, a qualitative analysis of the fatigue life under the vehicle load and residual stress field is carried out using the proposed method. A case analysis showed that when the residual tensile stress in the welding seam position is superimposed on the mainly tensile cyclic vehicle load stress, the longitudinal stress relaxation exceeds the peak vehicle load stress; significant longitudinal stress relaxation occurred, while the transverse stress relaxation is not significant. However, when the residual tensile stress is superimposed on the mainly compressive cyclic vehicle load stress, the relaxations of both the longitudinal and transverse stresses are not obvious. Compared with the stress state of the welding point under the action of only the vehicle stress, when the coupling effect of the residual stress and vehicle stress is considered, i.e., the loading condition, the fatigue stress state of the weld point has undergone an essential change under cyclic compressive stress, that is, the compressive stress state that does not require a fatigue check is changed to the tensile stress state. Although the fatigue state of the tensile stress cycle condition has not changed, the fatigue life is reduced by varying degrees under either the compressive or tensile condition

Self-Similarity Based Corresponding-Point Extraction from Weakly Textured Stereo Pairs

For the areas of low textured in image pairs, there is nearly no point that can be detected by traditional methods. The information in these areas will not be extracted by classical interest-point detectors. In this paper, a novel weakly textured point detection method is presented. The points with weakly textured characteristic are detected by the symmetry concept. The proposed approach considers the gray variability of the weakly textured local regions. The detection mechanism can be separated into three steps: region-similarity computation, candidate point searching, and refinement of weakly textured point set. The mechanism of radius scale selection and texture strength conception are used in the second step and the third step, respectively. The matching algorithm based on sparse representation (SRM) is used for matching the detected points in different images. The results obtained on image sets with different objects show high robustness of the method to background and intraclass variations as well as to different photometric and geometric transformations; the points detected by this method are also the complement of points detected by classical detectors from the literature. And we also verify the efficacy of SRM by comparing with classical algorithms under the occlusion and corruption situations for matching the weakly textured points. Experiments demonstrate the effectiveness of the proposed weakly textured point detection algorithm

catena-Poly[[bis­(nitrato-κ2 O,O′)zinc(II)]-μ-4,4′-bis­(pyrazol-1-ylmeth­yl)biphenyl-κ2 N 2:N 2′]

In the title compound, [Zn(NO3)2(C20H18N4)]n, the ZnII atom lies on a crystallographic twofold axis and the coordination geometry can be considered as a slightly distorted tetra­hedron defined by two O atoms from two nitrate groups and two N atoms from two ligand mol­ecules. A distorted octa­hedron may be assumed when two of the symmetry-related nitrate O atoms, with Zn—O distances of 2.528 (2) Å, are added to the coordination environment. Another twofold axis, passing through the middle of the biphenyl bonds, is observed in the crystal structure. A chain along [101] is built up by the ligands linking the ZnII ions