Partially bonded near-surface-mounted CFRP bars for strengthened concrete T-beams

A partially bonded strengthening approach for reinforced concrete (RC) beams utilizing near-surface-mounted (NSM) carbon fiber reinforced polymer (CFRP) bars was investigated with the specific objective of improving deformability. A total of six RC T-beams strengthened with NSM CFRP bars of various unbonded lengths were tested. Test results showed a decrease of the stiffness at the post-yield stage of the load–deflection response in the partially bonded beams. This is caused by the delayed increase of the FRP strain within the unbonded length. As a result the beam deformability was increased as the unbonded length increased at the same applied load. Internal slip of the FRP bar and gradual concrete failure were observed near the ultimate state, which caused a complicate nonlinear behavior of the beams. An analytical model is proposed to address the complete beam behavior including the effect of slip of FRP reinforcement and gradual concrete crushing. This model was developed based on the compatibility of deformation of the partially bonded system and was able to represent the ultimate behavior of the beams well.     

An investigation of speech enhancement using wavelet filtering method

This paper investigates the utilization of wavelet filters via multistage convolution by Reverse Biorthogonal Wavelets (RBW) in high and low pass band frequency parts of speech signal. Speech signal is decomposed into two pass bands of frequency; high and low, and then the noise is removed in each band individually in different stages via wavelet filters. This approach provides better outcomes because it does not cut the speech information, which occurs when utilizing conventional thresholding. We tested the proposed method via several noise probability distribution functions. Subjective evaluation is engaged in conjunction with objective evaluation to accomplish optimal investigation method. The method is simple but has surprise high quality results. The method shows superiority over Donoho and Johnstone thresholding method and Birge-Massart thresholding strategy method.     

Privacy Analysis of Forward and Backward Untraceable RFID Authentication Schemes

In this paper, we analyze the first known provably secure Radio Frequency Identification (RFID) authentication schemes that are designed to provide forward untraceability and backward untraceability: the L-K and S-M schemes. We show how to trace tags in the L-K scheme without needing to corrupt tags. We also show that if a standard cryptographic pseudorandom bit generator (PRBG) is used in the S-M scheme, then the scheme may fail to provide forward untraceability and backward untraceability. To achieve the desired untraceability features, we show that the S-M scheme can use a robust PRBG which provides forward security and backward security. We also note that the backward security is stronger than necessary for the backward untraceability of the S-M scheme.     

CRETACEOUS SOURCE ROCKS AT THE ABU GHARADIG OIL- AND GASFIELD, NORTHERN WESTERN DESERT, EGYPT

The Abu Gharadig oil- and gasfield is located in the north of the Western Desert of Egypt. In this paper, the geochemical characteristics of kerogens from Cretaceous shales at this field are described. The shale samples came from the Abu Roash Formation E and G Members (late Cenomanian- Turonian), the Bahariya Formation (early Cenomanian) and the Betty Formation (Neocomian- Barremian). Kerogen type and quality was evaluated by optical microscopy and by standard methods (elemental analysis, infrared spectroscopy and Rock-Eval pyrolysis). The results show that the shale samples analysed contain fair to high quantities of organic matter, and that this takes the form of marine amorphous sapropelic and structured liptinite macerals which can be classified as Types I and II kerogens.
Maturation indicators and burial history curves indicate that shales from the Abu Roash E and G Members are currently located in the oil-generation window. Oil generation in these units has taken place since the late Palaeocene-early Eocene—i.e. since the formation of structural traps in the Abu Gharadig area, which occurred in the Maastrichtian—Eocene. Shales in the Bahariya and Betty Formations passed through the oil window during the Late Cretaceous before the traps were formed, but the shales reached the wet-gas zone in the late Miocene - early Pliocene.
Most of the liquid hydrocarbons in the Abu Gharadig field are sourced by Cretaceous shales in the Abu Roash E and G Members; and most gas is generated by shales in the underlying Bahariya and Betty Formations. The Jurassic Khatatba Formation may also have generated some gas.     

Low-Temperature Preparation and Magnetic Properties of V-Doped SnO2 Nanoparticles

A solid solution of vanadium (V)-doped tin oxide (SnO₂) particles of average diameter 2 nm and V content of 19 at.% was prepared at normal pressure and low temperature (100°C) by mixing wet SnO₂ gel SnO₂· x H₂O with a boiling solution of vanadium oxide (V₂O₅). Experimental characterizations using X-ray, electron diffraction, and transmission electron microscope show evidence of a pure single phase. The nanoparticles exhibit a mixed magnetic behavior, namely paramagnetic and ferromagnetic. Their thermal stability is also investigated. At higher temperature, 850°C, some amount of Fe precipitates from the solid solution.     

Infrared spectra, Raman laser, XRD, DSC/TGA and SEM investigations on the preparations of selenium metal, (Sb2O3, Ga2O3, SnO and HgO) oxides and lead carbonate with pure grade using acetamide precursors

Ga₂O₃, Se metal, SnO, Sb₂O₃, HgO and PbCO₃ are formed upon the reaction of acetamide aqueous solutions with Ga(NO₃)₃, SeO₂, SnCl₂, SbCl₃, HgCl₂ and Pb(NO₃)₂, respectively, at 90°C. Different amorphous or crystalline phases can be obtained depending upon the experimental conditions (molar ratios, metal salts and temperature). The chemical mechanisms for the formations of this metal, oxides or carbonate are discussed and the X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscope (AFM) are described. The type of metal ions plays an important role in the decomposition of acetamide, leading to the formation of solid stable (metal, oxides or carbonate), soluble and gases species. These new precursors are more stable preventing the rapid precipitation of metal, oxides or carbonate. Furthermore, this route allows the formation of pure compounds in solutions.     

US Foreign Affiliates,Technology Diffusion and Host Country Human Development: Human Development Index versus Human Capital

In this study, we use a cross-sectionally correlated and timewise autoregressive model and panel data for the period 1966–2000 to investigate human development as a measure of host country absorptive capacity in 30 developed and developing countries. The results suggest that technology diffusion from US foreign affiliates has a positive and significant impact on labor productivity only if host countries have a minimum level of human development. This condition may partially explain why previous studies show mixed support for the hypothesis that foreign affiliates have a positive effect on productivity in developing countries. Although the results have to be interpreted with caution, the policy implication is that human development enhances the capacity of countries to reap the benefits of foreign direct investments.     

Elastic stability analysis of loosely fitted thin liners – A proposed simplified procedure and evaluation of existing solutions

The paper reports the results of an extensive numerical simulation to estimate the elastic buckling pressure and the corresponding thrust and bending moment induced in loosely fitted thin liners. The study is conducted numerically using a two-dimensional (2D) non-linear finite element model that accounts for the effects of large deformations on the stability of loosely fitted liners. The finite element results together with a non-linear multi-variant regression analysis are used to develop simplified non-dimensional formulae that provide the critical pressure, thrust and bending moments, at buckling, based on the liner’s geometry and material properties.In addition, several other analytical and numerical solutions for the same problem are revisited and critically reviewed. For comparison purposes, two of such methods are extended to allow for the calculation of the thrust and bending moment developed at the most heavily stressed point in the loosely fitted liners at the onset of buckling. In general, the comparison reveals the appropriateness of the proposed regression models in predicting the critical pressure and the associated thrust and bending moment induced in imperfect loosely fitted liners. Developed formulae provide designers with a simple and reliable means for ensuring stability and safety of such special type of structures.     

Electrochemical behavior of nickel in nitric acid and its corrosion inhibition using some thiosemicarbazone derivatives

The adsorption and corrosion inhibition behavior of three selected thiosemicarbazone derivatives, namely 3-pyridinecarboxaldehyde thiosemicarbazone (META), isonicotinaldehyde thiosemicarbazone (PARA) and 2-pyridinecarboxaldehyde thiosemicarbazone (ORTHO) at the nickel surface were studied electrochemically by Tafel and impedance methods and computationally by carrying out Monte Carlo searches of configurational space on nickel/thiosemicarbazone derivative system. Electrochemical measurements showed that the inhibition efficiency of these compounds increased with increase in their concentration. The recorded inhibition efficiencies of the three tested thiosemicarbazone increase in the order: META > PARA > ORTHO. Polarization studies showed that these compounds act as mixed-type inhibitors for nickel corrosion in 1.0 M HNO₃ solutions. Results obtained from Tafel and impedance methods are in good agreement. Thiosemicarbazone derivatives have been simulated as adsorbate on Ni (1 1 1) substrate and the adsorption energy, binding energy and the low energy adsorption sites have been identified on nickel surface.