Influence of Nanosilver Synthesis Conditions on its Architecture

Silver nitrate reduction in presence of Ethylene glycol (EG) and Polyethylene glycol (PEG) represents one from the simplest techniques for silver nano-powder fabrication. Where EG act as reducing agent and PEG act as stabilizing agent. The impact of presence either the reducing agent or the stabilizing agent at the reaction media on the properties of synthesized silver were recorded. Regarding to the chain length of PEG was discovered to play the key role in the formation of nano-silver. Accordingly, the variation in the stabilizing agent (PEG) molecular weight on the morphological structures of produced silver was recorded. The formation of nano-silver was confirmed using UV–Vis spectroscopy. The UV–visible scanning results for the aqueous reaction medium containing silver ion has been demonstrated characteristics peak at 420nm that corresponding to the plasmon absorbance of silver nanoparticle. X-ray diffraction (XRD) was utilized to determine the crystalline structure of the prepared silver nano-powders. The crystalline structure of prepared nano-silver was produced in hexagonal, cubic crystal and face centered cubic configurations with different plane of orientation. Scanning electron micrographs of synthesized silver indicated that nano-silver were prepared in morphological structures as nanoparticle

Influence of Nanosilver Synthesis Conditions on its Architecture

Silver nitrate reduction in presence of Ethylene glycol (EG) and Poly Ethylene glycol (PEG) represents one from the simplest techniques for silver nano-powder fabrication. Where EG act as reducing agent and PEG act as stabilizing agent. The impact of presence either the reducing agent or the stabilizing agent at the reaction media on the properties ofsynthesized silver were recorded. Regarding to the chain length of PEG was discovered to play the key role in the formation of nano-silver. Accordingly, the variation in the stabilizing agent (PEG) molecular weight on the morphological structures of produced silver was recorded. The formation of nano-silver was confirmed using UV–Vis spectroscopy. The UV– visiblescanning results for the aqueous reaction medium containing silver ion has been demonstrated characteristics peak at 420nm that corresponding to the plasmon absorbance of silver nanoparticle. X-ray diffraction (XRD) was utilized to determine the crystalline structure of the prepared silver nano-powders.The crystalline structure of prepared nano-silver was producein hexagonal, cubic crystal and face centered cubic configurations with different plane of orientation. Scanning electron micrographs of synthesized silver indicated that nano-silver were prepared in morphological structures as nano-particle.Keywords: Silver, Nano-structures, Nano-material, Reduction, Characterization

A review of size and geometrical factors influencing resonant frequencies in metamaterials

Although metamaterials and so-called left-handed media have originated from theoretical considerations, it is only by their practical fabrication and the measurement of their properties that they have gained credibility and can fulfil the potential of their predicted properties. In this review we consider some of the more generally applicable fabrication methods and changes in geometry as they have progressed, exhibiting resonant frequencies ranging from radio waves to the visible optical region

GIZA 11 AND GIZA 12; TWO NEW FLAX DUAL PURPOSE TYPE VARIETIES

Sixteen flax genotypes {13 promising lines and 3 check varieties viz., Giza 8 (oil type), Sakha 1 (dual purpose type) and Sakha 3 (fiber type)} were evaluated for straw, seed, oil yields and their related traits under twelve different environments; four locations (Sakha, Etay El-Baroud, Ismailia and Giza Exp. Stations through three successive seasons (2011/12, 2012/13 and 2013/14). These materials were evaluated in a randomized complete blocks design with three replications at the twelve above-mentioned environments. The analysis of variance revealed highly significant differences among genotypes (G), environments (E) and G x E interaction for all studied traits except straw weight per plant, indicating a wide range of variation among genotypes, environments and these genotypes exhibited differential response to environmental conditions. The significant variance due to residual for all characters except both straw weight per plant and oil yield per fad indicated that genotypes differed with respect to their stability suggesting that prediction would be difficult, which means that mean performance alone would not be appropriate. Interaction component of variance (σ2ge) was less than the genotypic variance (σ2g) for all characters, indicating that genotypes differ in their genetic potential for these traits. This was reflected in high heritability and low discrepancy between phenotypic (PCV) and genotypic (GCV) coefficients of variability values for these traits indicating the possibility of using each of long fiber percentage, plant height and technical stem length as selection indices for improving straw weight per plant, as well as, using 1000-seed weight and capsules number per plant as selection indices for improving seed weight per plant. Yield stability (YSi) statistic indicated that S.541-C/3 and S.541-D/10 gave high mean performance and stability for straw, fiber, seed and oil yields per fad in addition to oil percentage, capsules number per plant and 1000-seed weight. Therefore, the two genotypes well be released under the name Giza 11 and Giza 12, respectively. These newly released varieties are of dual purpose type for straw, fiber, seed and oil yield. They may replace the low yielding cultivars Giza 8, Sakha 1 and Sakha 3

Metallo-dielectric diamond and zinc-blende photonic crystals

It is shown that small inclusions of a low absorbing metal can have a dramatic effect on the photonic band structure. In the case of diamond and zinc-blende photonic crystals, several complete photonic band gaps (CPBG's) can open in the spectrum, between the 2nd-3rd, 5th-6th, and 8th-9th bands. Unlike in the purely dielectric case, in the presence of small inclusions of a low absorbing metal the largest CPBG for a moderate dielectric constant (epsilon<=10) turns out to be the 2nd-3rd CPBG. The 2nd-3rd CPBG is the most important CPBG, because it is the most stable against disorder. For a diamond and zinc-blende structure of nonoverlapping dielectric and metallo-dielectric spheres, a CPBG begins to decrease with an increasing dielectric contrast roughly at the point where another CPBG starts to open--a kind of gap competition. A CPBG can even shrink to zero when the dielectric contrast increases further. Metal inclusions have the biggest effect for the dielectric constant 2<=epsilon<=12, which is a typical dielectric constant at near infrared and in the visible for many materials, including semiconductors and polymers. It is shown that one can create a sizeable and robust 2nd-3rd CPBG at near infrared and visible wavelengths even for a photonic crystal which is composed of more than 97% low refractive index materials (n<=1.45, i.e., that of silica glass or a polymer). These findings open the door for any semiconductor and polymer material to be used as genuine building blocks for the creation of photonic crystals with a CPBG and significantly increase the possibilities for experimentalists to realize a sizeable and robust CPBG in the near infrared and in the visible. One possibility is a construction method using optical tweezers, which is analyzed here.Comment: 25 pp, 23 figs, RevTex, to appear in Phys Rev B. For more information look at http://www.amolf.nl/research/photonic_materials_theory/moroz/moroz.htm

New Recursive Formulas for Eigenvalue Sensitivity Analysis

Eigenvalue sensitivity analysis represents a key discipline in many engineering system applications where the dynamic behavior of such systems is closely related to the eigenvalues of the system (state) matrix. Currently available eigenvalue sensitivity evaluation methods are based on a general form of the system matrix derivatives with respect to the sensitivity parameter of interest. In many engineering systems, however, the structure of the system matrix is such that its derivatives with respect to practical system parameters constitute special rank-one forms. This paper presents a novel application of a compact matrix exchange formula to the eigenvalue sensitivity problem, which includes rank-one derivative matrices, leading to very fast recursive sensitivity formulas with substantial savings in computation time and memory requirements. With such recursive formulas, the evaluation of higher-order eigenvalue sensitivities is therefore attainable using previously calculated lower-order sensitivities. An illustrative application to power system dynamic stability analysis is presented in which the new eigenvalue sensitivity formulas were successfully used to estimate the effect of parameter changes on the dynamic system modes

Dynamic stability improvement via coordination of static var compensator and power system stabilizer control actions

Power system controllers such as the static var compensators and the power system stabilizers are receiving a wide interest since many technical studies have proven their effects on damping system oscillations and stability enhancement. This paper is mainly concerned with coordinating the control actions of static var compensators and power system stabilizers to achieve improved dynamic performance of the power system using the newly developed concept of 'domains of influence'. Novel sensitivity-based algorithms are presented for the purpose of effectively identifying the domains of influence of various control parameters on critical dynamic system modes. Applications to the Saudi Consolidated Electric Company (SCECO) power system show that significant improvement in power network stability can be achieved via coordinating the control actions of both static var compensator and power system stabilizer instead of using them individually in an uncoordinated manner. © 2001 Elsevier Science B.V

An Improved Algorithm for Efficient Computation of Current Distribution in Power Cables

Unequal current distribution inside underground cables in close proximity causes unfavorable induced voltages and losses in their sheaths. Because of the problem complexity, most previous researchers in the field have not modeled the skin and proximity effects with sufficient accuracy. In this paper, a new technique is presented for tackling the eddy current problem of non-magnetic multi-conductor systems. The technique utilizes an efficient impedance matrix formulation, which yields accurate current distribution assessment. Applications to a set of test cable systems are also presented in the paper to demonstrate the usefulness of the proposed technique

Probabilistic approach to electrical safety assesment in the development of effective building codes in Saudi Arabia

An important part of developing an effective building code is the adherence to strict safety codes. Electrical safety and the associated issue of fault current breaker performance, in particular, are extremely important in this regard since the nature of electricity consumption in the Kingdom of Saudi Arabia and the improved style of living have led to a continual increase in the consumption demand which inevitably resulted in a corresponding increase in the expected fault current levels resulting from faults taking place randomly in the building. This paper presents an advanced probabilistic fault current analysis methodology and the associated computerized algorithm which incorporate an efficient risk-assessment model in order to simulate, more accurately, the various fault current scenario aspects in buildings and evaluate the associated electrocution risk. The methodology presented is believed to assist the electrical building code developers in order to know and assess the probability of both electrocution hazards and domestic equipment failure due to excessive fault currents. The approach adopted utilizes the desirable features of the Monte Carlo simulation method as it provides a simple and reliable way of treating the statistical distributions associated with complicated electrical building components. A demonstrative application is also presented in the paper in order to illustrate the implementation features of the presented approach.Corresponding Author: Dr. Abdulhameed Alohaly, Electrical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh-11421 Riyadh, Saudi Arabia. Email: [email protected]