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Composite grinding machine for non-circular shaft parts, on the workpiece servo spindle high requirements.In order to overcome the vector control coordinate calculation of complex, slow response speed and other defects, this paper adopts the direct torque control scheme of asynchronous motor spindle servo control research.Using the Matlab/Simulink module library provides the basic module, built asynchronous electric spindle direct torque control system model.Coordinate transformation process were established, flux adjust step, flux observation, link and loop PID position control module, and the use of subsystem package technology package.The current loop, speed loop, ring in position and torque simulation test, the results show that, the method of direct torque control of asynchronous motor spindle control drive control system can obtain good static and dynamic response characteristics and the closed-loop response performance.

A series of new coordination polymers, namely, [Sr(H2EIDC)2(H2O)2]n (1),{[Pb(H2EIDC)2(H2O)](H2O)3}n (2), [Ag(H2EIDC)]n (3), and [Ba(H2EIDC)2(H2O)]n (4) (H2EIDC = 2-ethyl-1H-imidazole-4,5-dicarboxylate), were synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, X-ray diffraction and thermogravimetric analyses. Complex 1 is a 2D infinite gridlike (4,4)topological layer structure. Complex 2 is a 2D corrugated layer constructed by PbII atoms and H2EIDC– anions. Complex 3 is a 2D corrugated sheet consisting of 1D chains linked by short Ag···Ag interactions, and the three complexes are extended into 3D supramolecular structures by weak intermolecular forces such as hydrogen bonds and π–π stacking interactions. Complex 4 exhibits a 3D framework with 1D channels. Furthermore, the luminescent properties of complexes 1, 2, and 3 are also investigated.

Background and objectives: Acetabular dysplasia is often characterized by acetabular bone hyperplasia and osteonecrosis of the femoral head. These pathological changes can alter the position of the center of the femoral head, causing abnormal values on anteroposterior radiographs of the adult pelvis involving the Wiberg anterior center-edge (CE) angle, acetabular angle (Sharp angle), and acetabular head index, eventually resulting in the inaccurate diagnosis of acetabular dysplasia. Herein, we introduce and verify three X-ray indicators, offshoring index (OFI), moving up index (MUI) and teardrop baseline offshoring index (TBOI). All data will be expressed as relative ratios, as we expect to make an accurate diagnosis by avoiding the generation of errors resulting from measurement angles. Design: A single-center, diagnostic trial. Methods: Two hundred adult patients (100 female and 100 male) will be scheduled to undergo pelvic X-ray examinations at the Third Hospital of Hebei Medical University in China. The affected and healthy sides will be measured and analyzed using commercial software. Outcome measures and preliminary results: The primary outcome measure is the sensitivity of OFI of the femoral head for diagnosing adult acetabular dysplasia. Secondary outcome measures include the specificity, positive and negative predictive values, and positive and negative likelihood ratios of OFI, and sensitivity specificity, positive and negative predictive values, and positive and negative likelihood ratios of MUI and TBOI of the femoral head for diagnosing adult acetabular dysplasia as well as the rate of correct diagnosis; correlation of OFI, MUI and TBOI to CE angle, Sharp angle and acetabular head index; and risk factors for hip dysfunction as analyzed by logistic regression analysis. In our pre-tests, pelvic X-ray data from 241 male patients showed that the OFI, MUI and TBOI were 86.8 ± 0.6%, 75.8 ± 2.0% and 76.2 ± 0.5%, which closely correlated with CE angle, Sharp angle, and acetabular head index (AHI). Discussion: This study is designed to verify that three new X-ray indicators, OFI, MUI and TBOI, as diagnostic indicators for adult acetabular dysplasia, can increase diagnostic accuracy and effectively avoid diagnostic errors in comparison with the CE angle, Sharp angle, and AHI. Ethics and dissemination: The study was approved by the Ethics Committee of the Third Hospital of Hebei Medical University in China (approval No. KE2016-011-1). The study will be performed in accordance with the relevant laws and regulations of the Declaration of Helsinki. All the participatns will be fully informed of the study protocol and experimental process, and provide written informed consent with the premise of fully understanding the treatment plan. The results of this study will be disseminated in peer-reviewed journals or presented at scientific meetings. Trial registrations: This trial was registered in the Chinese Clinical Trial Registry with registration number: ChiCTR1800016375 (protocol version: 1.0).

For an undirected graph G, a zero-sum flow is an assignment of non-zero integers to the edges such that the sum of the values of all edges incident with each vertex is zero. We extend this notion to a more general one in this paper, namely a constant-sum flow. The constant under a constant-sum flow is called an index of G, and I(G) is denoted as the index set of all possible indices of G. Among others we obtain that the index set of a regular graph admitting a perfect matching is the set of all integers. We also completely determine the index sets of all r-regular graphs except that of 4k-regular graphs of even order, k ≥ 1.

In the title complex, [Co(C(8)H(9)N(2)O(4))(2)(H(2)O)(2)]·2C(3)H(7)NO, the Co(II) cation (site symmetry ) is six-coordinated by two 5-carb-oxy-2-propyl-1H-imidazole-4-carboxyl-ate ligands and two water mol-ecules in a distorted octa-hedral environment. In the crystal structure, the complex mol-ecules and dimethyl-formamide solvent mol-ecules are linked by extensive O-H⋯O and N-H⋯O hydrogen bonding into sheets lying parallel to (21).

In the title complex, [Ni(C(8)H(9)N(2)O(4))(2)(H(2)O)(2)]·4H(2)O, the Ni(II) ion is coordinated in a slightly distorted octa-hedral environment formed by two bis-chelating H(2)pimda (H(3)pimda is 2-propyl-1H-4,5-dicarb-oxy-lic acid) ligands and two coordinated water mol-ecules. In the crystal structure, a three-dimensional framework is formed by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds involving the solvent water mol-ecules, coordinated water mol-ecules, carboxyl-ate O atoms and the protonated N atoms of the H(2)pimda ligands. The propyl groups of each H(2)pimda ligand are disordered over two sets of sites with refined occupancies of 0.50 (2):0.50 (2) and 0.762 (11):0.238 (11). In one water solvent mol-ecule, one of the H atoms was refined as disordered over two sites of equal occupancy.

The title compound, [Ni(C(9)H(45)N(2)O(4))(2)(H(2)O)(4)]·2C(3)H(7)NO·2H(2)O, has the Ni(II) center coordinated by four water mol-ecules and two N atoms from two 1H-benzimidazole-5,6-dicarboxyl-ate ligands in an octa-hedral geometry. The mol-ecule inter-acts with the solvent water and dimethyl-formamide mol-ecules through N-H⋯O and O-H⋯O hydrogen bonds to form a three-dimensional supra-molecular network. The metal atom lies on a center of inversion.

In the title complex, [Ni(C(9)H(4)N(2)O(4))(C(12)H(8)N(2))(H(2)O)(2)](n), the Ni(II) atom is hexa-coordinated by one N and one O atom from two different 1H-benzimidazole-5,6-dicarboxyl-ate ligands, two N atoms from one 1,10-phenanthroline ligand and two water mol-ecules. The flexible 1H-benzimidazole-5,6-dicarboxyl-ate ligands link the Ni(II) centres, forming an infinite zigzag chain parallel to [001]. The crystal packing is governed by inter-molecular hydrogen-bonding inter-actions of the O-H⋯O, N-H⋯O and C-H⋯O types.

In the title mononuclear complex, [Ni(C(9)H(4)N(2)O(4))(H(2)O)(5)]·5H(2)O, the Ni(II) atom is six-coordinated by one N atom from a 1H-benzimidazole-5,6-dicarboxyl-ate ligand and by five O atoms from five water mol-ecules and displays a distorted octa-hedral geometry. Inter-molecular O-H⋯O hydrogen-bonding inter-actions among the coordinated water mol-ecules, solvent water mol-ecules and carboxyl O atoms of the organic ligand and additional N-H⋯O hydrogen bonding lead to the formation of a three-dimensional supra-molecular network.

In the title complex, [Ni(C8H9N2O4)2(H2O)2]·4H2O, the NiII ion is coordinated in a slightly distorted octa­hedral environment formed by two bis-chelating H2pimda (H3pimda is 2-propyl-1H-4,5-dicarb­oxy­lic acid) ligands and two coordinated water mol­ecules. In the crystal structure, a three-dimensional framework is formed by inter­molecular O—H⋯O and N—H⋯O hydrogen bonds involving the solvent water mol­ecules, coordinated water mol­ecules, carboxyl­ate O atoms and the protonated N atoms of the H2pimda ligands. The propyl groups of each H2pimda ligand are disordered over two sets of sites with refined occupancies of 0.50 (2):0.50 (2) and 0.762 (11):0.238 (11). In one water solvent mol­ecule, one of the H atoms was refined as disordered over two sites of equal occupancy.

In the title compound, [Ni(H(2)O)(6)](C(16)H(12)O(6))·H(2)O, the Ni(II) cation is located on a mirror plane and is coordinated by six water mol-ecules, two of which are also located on the mirror plane, in a distorted octa-hedral geometry. The 4,4'-(1,2-dihy-droxy-ethane-1,2-di-yl)dibenzoate anion is centrosymmetric with the mid-point of the central ethane C-C bond located on an inversion center. The uncoordinated water mol-ecule is located on a mirror plane. Extensive O-H⋯O hydrogen bonding is present in the crystal structure.

In the title complex, [Ag(C(3)H(3)N(4)O(2))](n), the Ag(I) atom is four-coordinated in a slightly distorted tetra-hedral coordination geometry by two N atoms from two tetra-zole-1-acetate (tza) ligands and two O atoms from the other two tza ligands. The tza ligand bridges two Ag atoms through the carboxyl-ate O atoms and simultaneously binds to the other two Ag atoms through the tetra-zole N atoms, forming a two-dimensional network parallel to (100).

The title compound, [Ni(C9H45N2O4)2(H2O)4]·2C3H7NO·2H2O, has the NiII center coordinated by four water mol­ecules and two N atoms from two 1H-benzimidazole-5,6-dicarboxyl­ate ligands in an octa­hedral geometry. The mol­ecule inter­acts with the solvent water and dimethyl­formamide mol­ecules through N—H⋯O and O—H⋯O hydrogen bonds to form a three-dimensional supra­molecular network. The metal atom lies on a center of inversion.

In the title mononuclear complex, [Ni(C9H4N2O4)(H2O)5]·5H2O, the NiIIatom is six-coordinated by one N atom from a 1H-benzimidazole-5,6-dicarboxylate ligand and by five O atoms from five water molecules and displays a distorted octahedral geometry. Intermolecular O—H...O hydrogen-bonding interactions among the coordinated water molecules, solvent water molecules and carboxyl O atoms of the organic ligand and additional N—H...O hydrogen bonding lead to the formation of a three-dimensional supramolecular network.