Study of planar structure applying reciprocity technique combined with MGEC and analysis of discontinuity

The 3D structure electromagnetic computation presents several difficulties related to the volume mesh. In fact, the entire volume space must be taken into account even the smallest details. In this article, we propose a formulation based on the reciprocity theorem combined with the generalized equivalent circuit method to model a planar 3D structure with both coaxial and planar excitation. The major advantage of this formulation is the fact to reduce the computational volume into 2D ones in the discontinuity plane. In addition, we focused on the calculation of the discontinuity between the excitation source and the planar structure to determine the exact behavior of the electric coaxial excitation model. The obtained current density, electric field distributions, and the input impedance are presented and discussed in the following sections. An approximately good agreement of input impedance with those obtained by the simulator and measurement is shown.     

Super-Resolution image Reconstruction Based on Iteration and Wavelet Transform

In this paper, we provide a super-resolution image reconstruction algorithm based on wavelet transform. Wavelet transform can separate high frequency and low frequency information of image. The more high frequency information can be obtained by using wavelet transform and the technique of image fusion. Meanwhile, reconstructed super-resolution image is produced by the iterative method. In iteration process, noise of image can be suppressed by applying method of wavelet threshold de-noising. The experiment results show that the algorithm can overcome the disadvantage of the classical interpolation method and effectively improve the resolution and PSNR of the image.     

基围虾冻藏过程中的品质变化

通过测定基围虾不同冻藏时间点(0、1、3、5、7周)质构、多酚氧化酶(PPO)活性、脂肪氧化、脂肪酸组成、风味及鲜度的变化,探究了对虾冻藏过程中品质变化的机理。结果表明,随着冻藏时间的延长,基围虾的黏附性逐渐增加,弹性、硬度、咀嚼性显著下降。PPO活性呈现先升后降的趋势。基围虾冻藏过程中脂肪氧化水平(TBARS)不断增加,饱和脂肪酸显著增加,多不饱和脂肪酸(PUFA)显著降低。基围虾冻藏过程中共检测出50多种挥发性风味物质,其中醇类和芳香族化合物含量降低,醛、酮及含氮化合物的含量增加。由ATP、ADP、AMP和HxR及Hx等鲜度指标的测定结果可知,基围虾冻藏7周后仍比较新鲜。虽然基围虾在冻藏过程中品质和营养价值降低,但仍较新鲜。     

用正交多小波压制信号的随机噪声

正交多小波可同时具有短支集，对称性或反对称性和正交性，这是一般的正交单小波所没有的性质。本文详细说明了应用GHM正交多小波对信号进行去噪处理原理，并给出实际例子说明该方法的有效性。     

Modeling and technical–economic optimization of an autonomous photovoltaic system

Solar energy technologies offer a clean and renewable energy source, and are essential components of a sustainable energy future. The current paper presents a method for technical–economic optimization of an autonomous photovoltaic system. The principal objective of this study is to find the optimum characteristics of a photovoltaic system, able to accomplish the energy requirements of a given load distribution, for a specific site.Mathematical models are exploited to analyze the working of the photovoltaic system. These models present an estimation of the recovered solar energy anywhere and anytime, an evaluation of the electric energy produced by a photovoltaic generator and a determination of the storage unit characteristics. Then, the optimizing step is done based on lack of energy to generate probability (LEGP), percentage of the surplus of energy produced (PSEP) and the cost of the kilowatt-hour produced (C_kWh).A case study has been presented to determine the optimal system configuration used to satisfy the requirements of a typical residential home located in Sfax, Tunisia.     

Size Effects in Thin Face-Centered Cubic Metals for Different Complex Forming Loadings

Influence of the size effects on the mechanical behavior of face-centered cubic metals was studied for complex loadings close to microforming ones. The effect of a reduction in thickness (t) over grain size (d) ratio on the mechanical behavior for high-purity nickel and copper is investigated for three different loadings by tensile and Nakazima tests (plane strain conditions and balanced biaxial expansion). Experimental results highlight a strong degradation of the mechanical properties of Cu and Ni when the t/d ratio is reduced below a critical value, independently of the strain path. However, this effect occurs if the equivalent plastic strain is larger than a critical level which is strain path dependent and related to the stress triaxiality. The current study reveals that plastic anisotropy is also affected by size effects. An excellent correlation is obtained between the t/d ratio and the thickness reduction, through the mean normal plastic anisotropy parameter which is widely used to estimate sheet formability. A size effect map based on forming limit diagrams is proposed to depict the optimal conditions of microforming.     

Synthesis,characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

A new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH₄ was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B₁₂ loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39890.     

Variations in essential oil and fatty acid composition during Myrtus communis var. italica fruit maturation

The essential oil and fatty acid composition of Myrtus communis var. italica fruit during its ripening was determined. The effect of the harvesting time on some physical properties of Myrtus fruits, fruit weight and moisture content, were significant. The increase of fruit weight (from 2.54 to 8.79 g% fruits) during ripeness was correlated positively with that of moisture content (from 28% to 72%). Fruit essential oil yields varied from 0.003% to 0.01% and showed a remarkable increase at 60 days after flowering to reach a maximum of 0.11%. Forty-seven volatile compounds were identified in fruit essential oils; 1,8-cineole (7.31–40.99%), geranyl acetate (1.83–20.54%), linalool (0.74–18.92%) and α-pinene (1.24–12.64%) were the main monoterpene compounds. Total fatty acid contents varied from 0.81% to 3.10% during fruit maturation and the predominant fatty acids were linoleic (12.21–71.34%), palmitic (13.58–37.07%) and oleic (6.49–21.89%) acids. The linoleic acid proportions correlated inversely with palmitic and oleic acids during all the stages of ripening.     

Numerical modeling of damage evolution of DP steels on the basis of X-ray tomography measurements

In order to couple the damage evolution and the stress state of DP steel grades, a new advanced GTN (Gurson-Tvergaard-Needleman) model was developed and implemented into a finite element code. This model is an extension of the original one. It takes into account the plastic anisotropy and the mixed (isotropic + kinematic) hardening of the matrix. Two different methods to compute the void volume fraction were developed and used within the constitutive equations. The first method is new and allows the accurate modeling of the observations of damage initiation and growth in DP steels measured using high-resolution X-ray absorption tomography ( [Bouaziz et al., 2008] and [Maire et al., 2008]). The second method is classic and assumes the additive decomposition of the total void volume fraction into a nucleation and a growth part. A parametric study is carried out to assess the effect of the kinematic hardening on some mechanical parameters such as the equivalent plastic strain, the triaxiality and the porosity. The numerical predictions are favorably compared to the experimental results.     

Composition and insecticidal activity of essential oil from Pistacia lentiscus L. against Ectomyelois ceratoniae Zeller and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

This study reports investigations on the chemical constituents and fumigant toxicity of Pistacia lentiscus L. (Anacardiaceae) essential oil against two major stored-date insects, carob moth Ectomyelois ceratoniae Zeller and Mediterranean flour moth Ephestia kuehniella Zeller. Results showed that P. lentiscus essential oil contained terpinene-4-ol (23.32%), α-terpineol (7.12%) and β-caryophyllene (22.62%) as major compounds. Fumigant toxicity tests showed that P. lentiscus oil was more toxic to E. kuehniella (LC₅₀ = 1.84 μl/l, LC₉₅ = 5.14 μl/l) than E. ceratoniae (LC₅₀ = 3.29 μl/l, LC₉₅ = 14.24 μl/l). The fecundity and hatching rate of both insects decreased with increases in concentration or exposure time to the oil. At 136 μl/l air, fecundities and hatching rates were respectively 35 eggs/female and 42.86% for E. ceratoniae and 78 eggs/female and 29.49% for E. kuehniella.