Gama radiation-induced graft copolymerization of N-p-hydroxyphenylmaleimide onto polypropylene films

Polypropylene (PP) films were grafted with N-p-hydroxyphenylmaleinide using γ-radiation. The effect of both monomer concentration and dose rate on the degree of grafting was measured. Characterization of the grafted PP films included IR spectroscopy, X-ray diffraction, mechanical properties, thermal stability and surface topology and the dyeing characteristics of the grafted films with different dyes were also investigated.     

Damage analysis of composites reinforced with Alfa fibers: Viscoelastic behavior and debonding at the fiber/matrix interface

In this article, we first review state‐of‐the‐art experimental techniques and measurements to characterize the mechanical properties of anisotropic vegetal alfa fibers, epoxy‐resin, and the behavior of the interphase between the matrix and alfa fibers. Second, we conduct experimental tests to determine the mechanical properties of fibers, resin, and the interphase. Third, we carry out a series of finite element simulations to predict damage initiation and to estimate crack propagation in alfa‐fiber/epoxy‐resin (AFER) composites. Different tests to determine the longitudinal Young's modulus of alfa fibers and epoxy resin as well as nanoindentation tests to obtain the transverse stiffness of the fibers are presented. Experimental results from the characterization are introduced in a micromechanical model to estimate, using the concept of the energy release rate (ERR), the matrix crack, and its interaction with interfacial debonding. The wettability problems in the preparation of vegetable composites and their effect on fiber‐matrix interfacial debonding are also addressed. The analysis of the damage behavior of AFER composites demonstrates that under load transverse to the fiber axis, a crack initiated in the matrix is propagated perpendicular to the direction of the load. Near the interface, the ERR decreases and this energy is higher in the presence of interfacial debonding areas generated by problems of fiber wettability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43760.     

Drying of Citrus sinensis Peels in an Inert Fluidized Bed: Kinetics,Microbiological Activity,Vitamin C,and Limonene Determination

Citrus sinensis peel drying kinetics in a fluidized bed with inert material were investigated. Drying impact on microbiological activity as well as limonene and vitamin C content was also studied. Drying parameters studied were as follows: temperatures of 40°C, 50°C, and 60°C; air velocities of 0.73 m/s and 0.85 m/s; and orange peel:sand weight ratios of 1:0, 1:1, and 1:2. High temperatures, high air velocity, and the presence of inert material increased the drying rate. Nine thin-layer drying models were fitted to the experimental data of Citrus sinensis peels. The Midilli et al. model was found to be the most suitable model for describing the drying kinetics of Citrus sinensis peels. Vitamin C and limonene content were higher in the product dried using a fluidized bed than in the sun-dried product. Drying of Citrus sinensis peel in a fluidized bed also may reduce microorganism growth, increasing storage life.     

Aspects of the behavior of some pentaerythritol ester base synlubes for turbo-engines

In this work a series of pentaerythritol esters have been synthesized. Dean Stark apparatus has been used to measure the water separated periodically as one of the resultants giving an indication about reaction progress. Elementary analyses, mean average molecular weight, i.r., viscosity, density and pour point have been determined for the prepared esters.Some physico-chemical behaviors and correlations have been deduced to characterize the prepared esters. Moreover, they shed the light on their suitability as base oils which may be used in formulations according to French Air specification 3514 (Nato 0–150) as compared with the commercial oil sample (Trubonycoil 13B) used in this respect.     

A Triple-Channel Encrypted Hybrid Fusion Technique to Improve Security of Medical Images

Assuring medical images protection and robustness is a compulsory necessity nowadays. In this paper, a novel technique is proposed that fuses the wavelet-induced multi-resolution decomposition of the Discrete Wavelet Transform (DWT) with the energy compaction of the Discrete Wavelet Transform (DCT). The multi-level Encryption-based Hybrid Fusion Technique (EbhFT) aims to achieve great advances in terms of imperceptibility and security of medical images. A DWT disintegrated sub-band of a cover image is reformed simultaneously using the DCT transform. Afterwards, a 64-bit hex key is employed to encrypt the host image as well as participate in the second key creation process to encode the watermark. Lastly, a PN-sequence key is formed along with a supplementary key in the third layer of the EbHFT. Thus, the watermarked image is generated by enclosing both keys into DWT and DCT coefficients. The fusions ability of the proposed EbHFT technique makes the best use of the distinct privileges of using both DWT and DCT methods. In order to validate the proposed technique, a standard dataset of medical images is used. Simulation results show higher performance of the visual quality (i.e., 57.65) for the watermarked forms of all types of medical images. In addition, EbHFT robustness outperforms an existing scheme tested for the same dataset in terms of Normalized Correlation (NC). Finally, extra protection for digital images from against illegal replicating and unapproved tampering using the proposed technique.     

γ-MnO_2结构模型现状与EMD的性能

介绍了γ-MnO2的结构模型的新近进展以及研究γ-MnO2结构的方法一阶跃电位电化学谱、汇聚光束电子衍射法和TEM法。指出EMD在碱性电液中比CMD有优越的性能。尽管同属γ-型,即使同为EMD,由于结构特性的不同,放电性能也不尽相同。讨论了在不同放电电压下相应的反应过程。     

Positioning and navigation of mobile robot

Positioning tracking is not a new idea as we have been seen from the ability of the GPS (Global Positioning System) to track the position of the object, in general with acceptable accuracy but the cost of GPS installation is expensive. However, in the case of detecting the exact position in signal-blocked closed environment (e.g. inside building, forest, mines and others); the accuracy factor provide by GPS is low. Thus, this project presents a positioning tracking system that is able to track the movement of an object within a small area or inside buildings. A complete set of the positioning tracking system consists of a pair of computer mechanical mouse and a microcontroller. From the position displayed on the computer screen, the position of the object can be located. The pair of mouse detects each movement of the object and sends the movement data to microcontroller. Linear, angular displacement and positioning calculation are also being discussed. From the results, it’s shown that the positioning system is applicable. However, some small errors are also occurred but in acceptable range. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Study on acrylamide-vinyl pyrrolidone copolymer

Summary The solution copolymerization of acrylamide (AAm) with N-vinyl pyrrolidone (NVP) was investigated using azobisisobutyronitrile (AIBN) as an initiator at 60°C. The study was performed by measuring the rate of the copolymerization reaction, the molecular weights and by determining the monomer reactivity ratios. In addition, the thermal properties (thermal conductivity, thermal diffusivity and volumetric heat capacity) of the resulted copolymers in aqueous solutions were investigated at various temperatures. The kinetic results and the apparent reactivity ratios indicate that NVP is more reactive than AAm towards the copolymerization process. The values of the thermal properties whowed that the behaviour of such parameters depend on the polymer concentration, the temperatures and the content of vinyl pyrrolidone in the copolymeric chains.     

Utilization of composite’s tensile properties for energy absorbing systems

This idea was inspired by the fact that huge energy absorption capability can be achieved if the longitudinal properties of composite structures are being utilized. This can only be done if the energy absorbing system postfailure scenario is mitigated to be tearing failure mechanism. In this paper, friction, crazing, circumferential expansion and tearing failure mechanisms were introduced and applied successfully to control the response of energy absorbing system to the applied load. The system was designed by slipping a solid cone into composite cone. The semi-cone angles used were 8°, 12°, 16° and 20°. The cone height and bottom diameter were kept constant for all cases as 100 mm and 76.2 mm, respectively. Force–stroke curves and deformation histories of typical specimens are presented and discussed. The results demonstrated that at first crush stage the energy is dissipated in the form of friction and crazing and the conical responded in an elastic manner, while the post-crush stage is dominated by tearing failure mechanisms.