Damping multi-model adaptive switching controller design for electronic air suspension system

This paper presents the design and verification of a damping multi-model adaptive switching controller for electronic air suspension (EAS) system. In order to improve the convergence rate of identification algorithm of conventional adaptive controller, multiple local linear full-car vehicle models of EAS system with fixed parameters are established according to the actual damping control process of EAS for different vehicle driving conditions and an adaptive model whose initial value of parameters can be re-assigned is introduced to enhance the system control precision. The model switching control strategy based on minimum error is used to select the best matching model online and the optimum damping force is regulated by adaptive control algorithm, thus constituting the damping multi-model adaptive control for EAS. Simulation results show that the control method proposed in this paper can improve the damping regulating performance of EAS effectively in wide range driving conditions, especially for the case of sudden change in driving conditions

3,9-Di-tert-butyl-2,4,8,10-tetra­oxaspiro­[5.5]undeca­ne

The title compound, C15H28O4, was prepared by the condensation of pivalaldehyde with penta­erythritol. In the crystal, the two halves of the mol­ecule are related by a crystallographic twofold rotation axis passing through the central spiro-C atom. The two non-planar six-membered heterocycles both adopt chair conformations with the two tert-butyl groups both located in the equatorial positions

2,2′-(p-Phenyl­enedimethyl­ene)bis­(propane-1,3-diol)

The mol­ecule of the title compound, C14H22O4, is centrosymmetric. In the crystal, the mol­ecules are linked through O—H⋯O hydrogen bonds into a three-dimensional network

Bis[μ-1,2-diphenyl-N,N′-bis­(di-2-pyridyl­methyl­eneamino)ethane-1,2-diimine]disilver(I) bis­(hexa­fluorido­phosphate) acetonitrile disolvate

In the centrosymmetric dinuclear title compound, [Ag2(C36H26N8)2](PF6)2·2C2H3N, the Ag+ ion is bound to four N atoms from two 1,2-diphenyl-N,N′-bis­(di-2-pyridyl­methyl­eneamino)ethane-1,2-diimine ligands in a distorted tetra­hedral geometry. The ligand adopts a twist conformation, coordinating two metal centers by three pyridyl N atoms and one imine N atom and spanning two Ag+ ions, resulting in the formation of a helical dimeric structure

3,9-Dimethyl-3,9-bis­(4-nitro­phen­yl)-2,4,8,10-tetra­oxaspiro­[5.5]undeca­ne

In the title compound, C21H22N2O8, both of the nonplanar six-membered heterocycles adopt chair conformations. The dihedral angle between the terminal benzene rings is 58.22 (11)°. Weak inter­molecular C—H⋯O inter­actions are observed in the crystal structure

Tetraethyl 2,2′-(2,3,5,6-tetrafluoro-p-phenylenedimethylene)dipropanoate1

In the mol­ecule of the title compound, C22H26F4O8, a crystallographic inversion centre is located at the centroid of the benzene ring. C—H⋯F and C—H⋯O intra­molecular hydrogen bonds are observed as well as an inter­molecular C—H⋯O inter­action

[(4S,5S)-2,2-Dimethyl-1,3-dioxolane-4,5-di­yl]bis­[N-(thio­phen-2-yl­methyl­idene)methanamine]

In the title compound, C17H20N2O2S2, the five-membered heterocycle exhibits an envelope conformation and the mol­ecular chirality and configuration are well preserved from l-tartaric acid. The dihedral angle between the two thio­phene rings is 17.0 (2)°. In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯S hydrogen inter­actions, which are effective in the stabilization of the crystal structure

Expression levels of apoptotic factors in a rat model of corticosteroid-induced femoral head necrosis

Purpose: To study the expression levels of apoptotic factors in corticosteroid-mediated femoral head necrosis (FHN) in rats. Methods: Sprague-Dawley (SD) rats (n = 60) bred adaptively for one week were randomly assigned to control and model groups (30 rats/group). A rat model of corticosteroid-induced femoral head necrosis was established. Then, 3 mL of blood drawn from the inferior vena cava of each rat was used for the assay of the expression levels of osteoprotegerin (OPG) and osteoclast differentiation factor (RANKL) in each group using enzyme-linked immunosorbent assay (ELISA). The caspase-3- and Bcl-2-+ve cells in each group were determined with immunohistochemical method. Results: Relative to control, serum OPG level of model group was significantly decreased, while the RANKL level was markedly raised (p < 0.05). The degree of empty lacunae in the model rats was markedly increased, relative to control. Caspase-3-+ve cells were more numerous in the model group than in control, while Bcl-2-positive cells were markedly decreased compared to control (p < 0.05). Conclusion: Apoptosis occurs in the rat model of femoral head necrosis. Glucocorticoids may regulate the apoptotic process by  upregulating caspase-3 and inhibiting Bcl-2. This provides a novel lead for FHN therapy. Keywords: Femoral head necrosis, Corticosteroid, Glucocorticoid, Apoptosi

rac-3,9-Bis(3-chloro­phen­yl)-2,4,8,10-tetra­oxaspiro­[5.5]undeca­ne

In the title compound, C19H18Cl2O4, the two non-planar six-membered heterocycles passing through the spiro-C atom both adopt chair conformations, and the dihedral angle between the two benzene rings is 7.2 (1)°. In the crystal, the enanti­omers with R and S configurations are generated by the symmetry elements of the centrosymmetric space group, forming a racemic crystal. Inter­molecular C—H⋯π and weak C—H⋯O inter­actions link the mol­ecules in the crystal structure