Dynamic Vehicle-Track-Structure Interaction Analysis using Lagrange Multipliers

In the design of bridges and other overhead structures that support high-speed trains, particularly complex or unproven structural systems, an analysis accounting for the dynamic interaction between the train and the structure is required. This is termed dynamic vehicle-track-structure interaction (VTSI). In this paper, we present an approach to such analysis where the bridge structure and the train are modeled independently and coupled by time-varying kinematic constraints. Specifically, displacements of the train wheels are constrained to be equal to the track displacements at their locations. The contact forces between the wheels and the track appear in this formulation as Lagrange multipliers corresponding to these constraints. Particular consideration is needed in the interpolation of the constraints to avoid spurious oscillations in the Lagrange multipliers, and consequently accelerations, which we solve using a cubic B-spline constraint interpolation. For three-dimensional bridge and train models, including curved bridges, we adopt a corotational approach to representing the deformations of the suspension system within the vehicle body. We also use an energyconserving time integration scheme that reduces to Newark's constant average acceleration method in the absence of constraints. Implementation in the structural analysis software LARSA 4D is discussed, with particular emphasis on implications for users. ABSTRACT In the design of bridges and other overhead structures that support high-speed trains, particularly complex or unproven structural systems, an analysis accounting for the dynamic interaction between the train and the structure is required. This is termed dynamic vehicletrack-structure interaction (VTSI). In this paper, we present an approach to such analysis where the bridge structure and the train are modeled independently and coupled by timevarying kinematic constraints. Specifically, displacements of the train wheels are constrained to be equal to the track displacements at their locations. The contact forces between the wheels and the track appear in this formulation as Lagrange multipliers corresponding to these constraints. Particular consideration is needed in the interpolation of the constraints to avoid spurious oscillations in the Lagrange multipliers, and consequently accelerations, which we solve using a cubic B-spline constraint interpolation. For three-dimensional bridge and train models, including curved bridges, we adopt a corotational approach to representing the deformations of the suspension system within the vehicle body. We also use an energy-conserving time integration scheme that reduces to Newark's constant average acceleration method in the absence of constraints. Implementation in the structural analysis software LARSA 4D is discussed, with particular emphasis on implications for users

Nonlinear Elasticity in Biological Gels

Unlike most synthetic materials, biological materials often stiffen as they are deformed. This nonlinear elastic response, critical for the physiological function of some tissues, has been documented since at least the 19th century, but the molecular structure and the design principles responsible for it are unknown. Current models for this response require geometrically complex ordered structures unique to each material. In this Article we show that a much simpler molecular theory accounts for strain stiffening in a wide range of molecularly distinct biopolymer gels formed from purified cytoskeletal and extracellular proteins. This theory shows that systems of semi-flexible chains such as filamentous proteins arranged in an open crosslinked meshwork invariably stiffen at low strains without the need for a specific architecture or multiple elements with different intrinsic stiffnesses.Comment: 23 pages, 5 figures, submitted to Natur

Synthesis and thermal properties of a novel schiff base oligomer with a double azomethine group and its Co(II) and Mn(II) complexes

Schiff base oligomer of N,N'-bis (2,4-dihydroxybenzylidene) 1,2-phenylenediamine (DHBPDA), with a double azomethine group, was synthesized from the oxidative polycondensation (OP) reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90C. About 75% DHBPDA was converted to O-DHBPDA. The structures of the products were studied by UV-Vis, FT-IR, 1H-NMR, 13C-NMR and elemental analysis. According to Gel Permeation Chromatography (GPC) analysis of O-DHBPDA, the number average molecular weight (Mn), weight average molecular weight (Mw) and PDI values were found to be 4328g mol-1, 6228g mol-1 and 1.43, respectively. TG/DTA analyses were shown to be stable of O-DHBPDA against thermo-oxidative decomposition. During the polycondensation reaction, a part of the azomethine (-CH=N-) groups oxidized to aldehyde (CHO) group (10-12%). Oligomer-metal complexes of oligo-N,N'-bis (2,4-dihydroxybenzylidene) 1,2-phenylenediamine (O-DHBPDA) with Co(II) and Mn(II) were synthesized and characterized by FT-IR, UV-Vis, TG-DTA and Atomic Absorption Spectroscopy (AAS). The residue of DHBPDA, O-DHBPDA, O-DHBPDA-Co and O-DHBPDA-Mn were found to be 0%, 3.65%, 11.67%, and 9.20%, respectively at 1000C.National Council for Scientific Research: 106 T 365The authors thank the Scientific and Technological Research Council (Tübitak) for financial support (Project Number 106 T 365). Also thanks are due the METU-Central Lab. for 13C-NMR and TG/DTA analyses

Effect of long-chain amines on the extraction of boron from CaCl2 brine with CTMP in petroleum benzine

The effect of TOA (tri-n-octylamine), TOMA (tri-n-octylmethylammonium iodide), DEDA (N,N'-didodecylethylenediamine), DEDMA (N,N'-didodecyl-N,N'-tetramethylethylene-diammonium diiodide), and NDM (N-dodecylmorpholine) upon the solvent extraction of boron from CaCl2 brine with CTMP [2-chloro-4(1,1,3,3,-tetramethylbutyl)-6-methylolphenol] in petroleum benzine has been studied. In order to extract boron effectively and reject other cations such as Ca2+, the extraction of boron with CTMP was investigated in terms of extractant, the concentration of an amine, and solvent polarity. The results show that in the presence of long-chain amines, boron extraction with CTMP in all solvent systems was shifted To a more acidic pH range. Larger extraction, hence distribution, and an increase in selectivity are observed when CTMP is used together with long-chain amines and their ammonium salts in petroleum benzine

Synthesis, characterization and thermal poroperties of oligo-N,N'-bis (2,4-dihydroxybenzylidene) ethylenediamine and its cobalt (II) and manganese (II) complexes

In this study, the new oligomer Schiff base oligo-N,N'-bis (2,4-dihydroxybenzylidene) ethylenediamine (O-DHBEDA), with a double azomethine group, was synthesized by oxidative polycondensation (OP) of N,N'-bis (2,4-dihydroxybenzylidene) ethylenediamine (DHBEDA) with NaOCl as an oxidant in an aqueous alkaline medium at 90°C. About 69.3% DHBEDA was converted to O-DHBEDA. The structures of the products were studied by UV-Vis, FT-IR, 1H-NMR, 13C-NMR and elemental analysis. According to gel-permeation chromatography (GPC) analysis of O-DHBEDA, the number-average molecular weight (M n), weight-average molecular weight (M w) and PDI values were found to be 5255 g/mol, 9116 g/mol and 1.73, respectively. During the polycondensation reaction, a part of the azomethine (-CH=N-) groups oxidized to aldehyde (CHO) groups (approx. 4%). Oligomer-metal complexes of oligo-N,N'-bis (2,4-dihydroxybenzylidene) ethylenediamine (O-DHBEDA) with Co (II) and Mn (II) were synthesized and characterized by FT-IR, UV-Vis, TG-DTA and atomic absorption spectroscopy (AAS). TG/DTA analyses were shown to be stable of O-DHBEDA against thermo-oxidative decomposition. The residue values of DHBEDA, O-DHBEDA, O-DHBEDA-Co and O-DHBEDA-Mn were found to be 0%, 7.1%, 14% and 13.4%, respectively, at 1000°C. © 2008 Koninklijke Brill NV.106 T 365The authors thank The Scientific and Technological Research Council (Tübitak) for financial support (Project Number 106 T 365). Also thanks the METU-Central Lab. for 1H and 13C-NMR and TG/DTA analyses

Synthesis, characterization, and biological properties of Ni(II), Co(II), and Cu(II) complexes of Schiff bases derived from 4-aminobenzylamine

New Schiff bases, N,N'-bis(salicylidene)-4-aminobenzylamine (H2L1), N,N'-bis(3-methoxysali- cylidene)-4-aminobenzylamine (H2L2), and N,N'-bis(4-hydroxysalicylidene)-4-aminobenzylamine (H2L3), with their nickel(II), cobalt(II), and copper(II) complexes have been synthesized and characterized by elemental analyses, electronic absorption, FT-IR, magnetic susceptibility, and conductance measurements. For the ligands, 1H and 13C NMR and mass spectra were obtained. The tetradentate ligands coordinate to the metal ions through the phenolic oxygen and azomethine nitrogens. The keto-enol tautomeric forms of the Schiff bases H2L1, H2L2, and H2L3 have been investigated in polar and apolar solvents. All compounds were non-electrolytes in DMSO (~10-3 M) according to the conductance measurements. Antimicrobial activities of the Schiff bases and their complexes have been tested against Acinobacter baumannii, Pseudomonas aeruginosa, Micrococcus luteus, Bacillus megaterium, Corynebacterium xerosis, Staphylococcus aureus, Escherichia coli, Candida albicans, Rhodotorula rubra, and Kluyveromyces marxianus by the disc diffusion method; biological activity increases on complexation. © 2009 Taylor & Francis.Institute for Research in Fundamental Sciences: FEF2006BAP-15The authors are grateful to the Science Research Fund of the C¸ ukurova University in Turkey for supporting this work (Project number: FEF2006BAP-15) and to the Department of Chemistry for allowing using the laboratory facilities

SOIL IMPROVEMENT TO COUNTER LIQUEFACTION USING COLLOIDAL SILICA GROUT

Soil liquefaction due to earthquakes is a major reason of damage to buildings and other structures. This study deals with soil improvement against liquefaction by injection of a particular stabiliser, colloidal silica, which is nontoxic and stable. Laboratory experiments were performed to determine the effects of colloidal silica grout injection regarding soil strength and deformations. The experiments involved static and dynamic triaxial tests on untreated and treated soil samples. The variables used in the tests are the relative density (loose - 40%, medium - 60% and dense - 80%), the confining pressure (100 and 300 kPa), and the curing period of silica treated samples (7 and 28 days). The results clearly indicate the significant increase in strength of the soil with colloidal silica injection. Furthermore, the relative increase is the highest in the sand of the lowest relative density which is the most probable candidate for soil improvement. The observations that the increase in the strength of colloidal silica treated sands with curing time is gradual and continuous add to the advantage of this method for use in soil improvement works. By using the dynamic test results, the equivalent Young modulus (or shear modulus) and the hysteretic damping ratio of untreated and treated soils are compared.C1 [Manav, Y.; Karakaplan, E.; Inel, M.] Pamukkale Univ, Dept Civil Engn, Kinikli Campus, Denizli, Turkey.[Toprak, S.] Gebze Tech Univ, Civil Engn Dept, TR-41400 Gebze, Kocaeli, Turkey

Extraction of boron with diols in petroleum benzine and n-amyl alcohol

In the present work, the solvent extraction of boron with 2-ethyl-1,3-hexanediol (EHD), 1,2-dihydroxy-4-oxadodecane (DHD) and 3-(4-tert-butylphenoxy)-1,2-propanediol (BFPD) in petroleum benzine and n-amyl alcohol was thoroughly studied as a function of equilibrium pH. The pH(0.5) values for EHD, DHD and BFPD were determined from R %-pH graphs as 8.3, 2.7 and 2.3 in n-amyl alcohol, respectively. The extraction efficiencies of these diols were also comparatively investigated. The extraction efficiency in both solvents for each extractant was ranged from 78 to 98%. Stripping of boron was achieved as 96% for EHD with NaOH and 81% for BFPD with H2SO4