Contact problem for two perfectly bonded dissimilar infinite strips

In this paper a finite contact problem for two perfectly bonded dissimilar infinite strips is formulated in terms of singular integral equations. Both of the strips are assumed to be isotropic and uniaxial tension is applied to the lower strip away from the contact region. The contact stresses, stress intensity factors and stress distributions in the strips are obtained for various geometries and material combinations. It is also shown that the contact stresses become infinite at the contact ends with a typical square-root singularity.

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Résumé On exprime un problème de contact fini de deux bandes infinies différentes et parfaitement assemblées sur une longueur finie sous la forme d'intégrales singulières. On Suppose que chacune des bandes est isotrope, et qu'une tension uniaxiale est appliquée à la bande inférieure, à une distance suffisante de la zone de contact. On obtient pour diverses géométries et combinaisons de matériaux les contraintes de contact, les facteurs d'intensité de contraintes et les distributions des contraintes dans les bandes. On montre également que les contraintes de contact deviennent infinies aux extrémités de la zone de contact, et présentent une singularité typiquement exprimée par la racine carrée de leur valeur.

     

Periodically Ordered Meso‐ and Macroporous SiO2 Thin Films and Their Induced Electrochemical Activity as a Function of Pore Hierarchy

Silica thin films with variable pore hierarchy (different combinations of small meso‐, large meso‐, and macropores) were produced via evaporation induced self‐assembly in a one‐pot synthesis. A suitable block copolymer and an ionic liquid served as porogens for the generation of different types of mesopores whereas polymethylmethacrylate particles were used as macrotemplate. The silica architectures were characterized by various state‐of‐the‐art techniques, such as 2D‐SAXS, TEM, SEM, AFM, krypton and nitrogen sorption. Moreover, electrochemical functionalization was utilized as a tool to study the hierarchy‐property relationship. Thus, hierarchically porous films prepared on FTO‐coated glass were post‐synthetically silylated and electrochemically active ferrocene groups subsequently grafted onto the pore walls. Cyclic voltammetry was used to monitor the induced electrochemical activity as a function of variations in the pore hierarchy. It turned out that multimodal pore systems possess a relatively higher electrochemical response due to better connection between the pores and higher surface area.     

The Relation Between the Refractive Index of the Equatorial Ionospheric F2 Region and Long-Term Solar Indices

Ionospheric refractive index is especially important in the reflection and propagation of HF (3–30 MHz) waves from the ionosphere. For this reason, in this study, the relation between the real parts (μ\(_{0}^{2}\), μ\(_{x}^{2}\) and μ\(_{p}^{2}\)) of the refractive index computed as based on the direction of the Earth’s magnetic field for 300 km altitude in the equatorial ionospheric F2 region and the long-term solar indices (Sunspot Number-R12, Solar Flux at 10.7 cm -F10.7, Coronal Mass Ejection-CME) has been examined by using the multiple regression model. As a result of the examinations, it has been determined that there is a very strong relation between the three refractive index values and solar indices. While it was determined that the R12 and F10.7 indices have a very strong relation, it was also determined that CME did not have a statistically significant relation. This insignificant situation may only be explained with the magnetic field of the Earth acting like a shield.     

Application of Box-Wilson experimental design method for 2,4-dinitrotoluene treatment in a sequential anaerobic migrating blanket reactor (AMBR)/aerobic completely stirred tank reactor (CSTR) system

A sequential aerobic completely stirred tank reactor (CSTR) following the anaerobic migrating blanket reactor (AMBR) was used to treat a synthetic wastewater containing 2,4-dinitrotoluene (2,4-DNT). A Box-Wilson statistical experiment design was used to determine the effects of 2,4-DNT and the hydraulic retention times (HRTs) on 2,4-DNT and COD removal efficiencies in the AMBR reactor. The 2,4-DNT concentrations in the feed (0-280 mg/L) and the HRT (0.5-10 days) were considered as the independent variables while the 2,4-DNT and chemical oxygen demand (COD) removal efficiencies, total and methane gas productions, methane gas percentage, pH, total volatile fatty acid (TVFA) and total volatile fatty acid/bicarbonate alkalinity (TVFA/Bic.Alk.) ratio were considered as the objective functions in the Box-Wilson statistical experiment design in the AMBR. The predicted data for the parameters given above were determined from the response functions by regression analysis of the experimental data and exhibited excellent agreement with the experimental results. The optimum HRT which gave the maximum COD (97.00%) and 2,4-DNT removal (99.90%) efficiencies was between 5 and 10 days at influent 2,4-DNT concentrations 1-280 mg/L in the AMBR. The aerobic CSTR was used for removals of residual COD remaining from the AMBR, and for metabolites of 2,4-DNT. The maximum COD removal efficiency was 99% at an HRT of 1.89 days at a 2,4-DNT concentration of 239 mg/L in the aerobic CSTR. It was found that 280 mg/L 2,4-DNT transformed to 2,4-diaminotoluene (2,4-DAT) via 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) in the AMBR. The maximum 2,4-DAT removal was 82% at an HRT of 8.61 days in the aerobic CSTR. The maximum total COD and 2,4-DNT removal efficiencies were 99.00% and 99.99%, respectively, at an influent 2,4-DNT concentration of 239 mg/L and at 1.89 days of HRT in the sequential AMBR/CSTR.