Numerical simulation of residual stress induced by roll-peening

There are various techniques to improve the components resistance against oscillating loads or fatigue. One of the most efficient techniques is to induce a compressive residual stress layer on the surface of the component. This can be accomplished by different methods such as surface coating, shot-peening, heat treatment, laser peening and roll-peening. The latter is widely used for surface modification of flat and cylindrical industrial components such as crankshaft and etc. The distribution, layer thickness, and the maximum of residual stress induced by roll-peening can be influenced by parameters of rolling such as work piece material, radius of roller curved boundary, roller angular velocity, roller transverse speed, and rolling depth. In this work the effect of these parameters are studied by numerical simulations. The material used in this work is AISI 4340. The roller is a solid disk with a curved boundary. The results indicate that: (i) the surface residual stress increases with the increase of rolling depth up to a specific value thereafter begins to decline; (ii) the effect of roller curvature radius on surface residual stress shows exactly the same trend as the rolling depth does; (iii) for a strain rate hardened material which is the case for the material used in this work, the angular velocity of the roller gives rise to the increase of the surface residual stress and finally, (iv) the increase of the transverse speed of the roller brings about the reduction in the residual surface, as expected.     

Nickel electrodeposition on copper substrate for cyclotron production of <Superscript>64</Superscript>Cu

Natural nickel electrodeposition on a copper substrate with a gold layer was studied with the aim of production of ⁶⁴Cu radionuclide. The electrodeposition experiments were carried out in acid plating baths. The operating parameters such as pH, temperature, and current density were optimized. The current efficiency was measured at different current densities. The optimum conditions of the nickel electrodeposition are as follows: 5.7 g 1⁻¹ nickel, pH 3–4, dc current density 85.54 mA cm⁻², and 55°C, with 97% current efficiency. SEM photomicrographs demonstrated fine-grained structure of the deposit obtained from the optimum bath. A 46-μm high-quality layer was deposited on a gold layer of the copper substrate.     

Poly(ε-caprolactone) electrospun nanofibers containing curcumin nanocontainers: enhanced solubility,dissolution and physical stability of curcumin via formation of inclusion complex with cyclodextrins

Supramolecular nanocontainers of cyclodextrins (α- and β-CD)/curcumin (CUR) were prepared by inclusion complex (IC) forming between CDs and guest molecule at two conditions. Formation of the inclusion complex between CDs and CUR at various conditions in solid phase was characterized by various methods. Solubility and in vitro dissolution of obtaining CUR nanocapsules were investigated and results showed that encapsulation of CUR, improved CUR bioavailability with a controllable release. Electrospun nanofibers of poly-ε-caprolactone (PCL) containing CUR/CDs inclusion complex of various conditions have been fabricated using a conventional electrospinning process and indicated that these nanofibers are bead-free.     

The corrosion inhibition of Ti-alloy (VT-9) in mixture of H<Subscript>2</Subscript>SO<Subscript>4</Subscript>-NaF by organic compounds

This investigation deals with corrosion behavior of high strength titanium alloy in concentrated sulphuric acid solution containing different concentrations (500, 1000, 1500 ppm) of fluoride ion (F⁻) using various organic compounds (MPA, L-OH, NFP) as inhibitor, potentiodynamically. The open circuit potential values noted before and after each experiment, varied appreciably. These values were negative before polarization but after completion of the experiment turned positive and remained stable over long period of time. It is observed that cathodic current density values increase with increasing cathodic potential (more negative) and fluoride ion. The values of cathodic Tafel slopes derived from the curves (∼110 − 140 mV/dec I) indicate hydrogen evolution reaction (h.e.r). The corrosion potential (E _corr) varied slightly with addition of inhibitors. The corrosion current densities (I _corr) increased with increasing fluoride ion concentration, but these values decreased appreciably when inhibitor (MPA) was used. SEM micrograph reveals reduction of pits in the presence of inhibitor (MPA). So this concludes that organic compound was used in this case acts as a good inhibitor. The article is published in the original.     

Endothelial-selectin ligands sialyl Lewis(x) and sialyl Lewis(a) are differentiation antigens immunogenic in human melanoma

BACKGROUND: Sialyl Lewis(x) (sLe(x)) and sialyl Lewis(a) (sLe(a)), the endothelial-selectin ligands involved in extravasation of neutrophils and carcinomas, have been identified in human melanoma. This study explored the following issue: If these ligands are immunogenic tumor-differentiation antigens, they would be potential targets for immunotherapy because of their putative roles in extravasation and metastasis. METHODS: Using a cell-suspension enzyme-linked immunosorbent assay (ELISA), the expression of sLe(x) and sLe(a) on the surface of normal melanocytes, melanoma cells from biopsies, and cell lines (M10-v, M24, and M101) constituting melanoma cell vaccine (MCV) were quantitated. Melanoma patients were immunized with the MCV expressing these antigens. Sera of normal individuals, sera of patients, and sera that adsorbed to sLe(x) and sLe(a) were titrated for anti-sLe antibodies by ELISA to verify the immunogenicity of the ligands. RESULTS: The normal melanocytes did not express sLe(x) and poorly expressed sLe(a). Melanoma cells from tumor biopsies and MCV lines expressed both sLe(x) and sLe(a). Sialyl Le(x) was associated with glycoprotein(s) in M10-v, and sLe(a) occurred as a glycolipid moiety in M24. MCV recipients developed high titers for immunoglobulin (Ig)M but not IgG to both ligands. IgM titers to these ligands were low in normal subjects. In some of the preimmune sera of patients, the titers were threefold above normal. Six of 13 MCV recipients developed at least a twofold increase in anti-sLe titers above preimmune level after the second or third immunization. Adsorption studies suggested that both ligands were immunogenic. CONCLUSIONS: The melanoma-associated sLe(x) and sLe(a) are immunogenic neoplasm-differentiation antigens and are therefore potential targets for passive and active specific immunotherapy in the treatment of melanoma.     

Multiperiod cellular network design via price-influenced simulated annealing (PISA).

Cellular telecommunications systems tend to be more flexible than traditional ones. As a result, traditional approaches to telecommunications network design are often inappropriate for the design of cellular networks, and approaches that explicitly incorporate the increased flexibility into the design process need to be developed. This paper presents one such multiperiod cellular network design problem and solves it via a hybrid heuristic that incorporates ideas from linear programming (LP) and simulated annealing (SA). Extensive computational results comparing the performance of the heuristic with the lower bound obtained from the LP relaxation are presented. These results indicate that this price-influenced simulated annealing (PISA) procedure is extremely efficient, consistently providing solutions with average gaps of 0.30% or less in fewer than 30 s.     

A variable parameters multivariate control chart for simultaneous monitoring of the process mean and variability with measurement errors

Evaluating the effect of measurement errors on either adaptive or simultaneous control charts has been a topic of interest for the researchers in the recent years. Nevertheless, the effect of measurement errors on both adaptive and simultaneous monitoring control charts has not been considered yet. In this paper, through extensive numerical studies, we evaluate the effect of measurement errors on an adaptive (variable parameters) simultaneous multivariate control chart for the mean vector and the variance-covariance matrix of p quality characteristics assumed to follow a multivariate normal distribution. In order to do so, (a) we use eight performance measures computed using a Markov chain model, (b) we consider the effects of multiple measurements as well as the error model's parameters, and (c) we also consider the overall performance of this adaptive simultaneous chart including the chart parameters values optimization, which have never been considered so far for this scheme. At last, a real case is presented in order to illustrate the proposed scheme.     

A sparsity-based Bayesian approach for hyperspectral unmixing using normal compositional model

A new Bayesian-based method is developed for unmixing of hyperspectral images. Endmembers are assumed variable based on the Gaussian distribution. A semi-supervised scenario is considered, and as a practical aspect, the abundance vectors are assumed sparse. We propose the Dirichlet prior to represent the sparsity and derive the corresponding posteriors in Bayesian sense. Numerical results are used to evaluate different methods for both simulated and real data. It is shown that the proposed method achieves a lower error in abundance estimation and image reconstruction.     

Preparation of polyvinylchloride membranes from solvent mixture by immersion precipitation

In this study, polyvinylchloride (PVC) membranes were prepared through the immersion precipitation method using a mixture of two solvents (tetrahydrofuran (THF) and dimethyl formamide (DMF)), which had different affinities with the nonsolvent (water). Membranes prepared from PVC/THF/water system showed a sponge‐like structure with isolated pores, which were impermeable to water even at a feed pressure of 20 bars, whereas those prepared from PVC/DMF/water exhibited a porous macrovoid containing morphology with a high water flux. The precipitation time and polymer concentration profiles were calculated by using a simple mathematical model and were in good agreement with the experimental findings on PVC/THF/water and PVC/DMF/water systems. By using a mixture of DMF and THF as solvent and changing the mixed solvent composition, membranes with different morphologies from sponge‐like to macrovoid containing were obtained. The membranes showed no water flux below a DMF concentration of 50 wt % and then became increasingly permeable with increasing DMF content in the casting solution. Measurement of the system cloud points showed a linear change of system thermodynamics with variation of the mixed solvent composition. The obtained results showed that although the system thermodynamics could explain the overall behavior of the system, but the local changes such as change of membrane performance from impermeable to permeable at a certain mixed solvent composition could not be explained by the thermodynamics alone. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40206.