The Effect of Plasma Spraying on the Microstructure and Aging Kinetics of the Al-Si Matrix Alloy and Al-Si/SiC Composites

The Al-Si (LM 13)-based matrix alloy reinforced with SiC particles containing 10, 20, and 30 vol.% SiC particles were spray-formed onto Al-Si substrates. The sprayed samples were directly subjected to a standard aging treatment (T551). From the experiments, it was observed that the high rate of solidification resulted in very fine silicon particles which were observed as continuous islands in the matrix and each island exhibited several very fine silicon crystals. Analysis showed that plasma-spraying caused an increased solid solubility of the silicon in the aluminum matrix. DSC measurements in the permanent mold-cast Al-Si matrix alloy and plasma-sprayed Al-Si matrix alloy showed that plasma-spraying causes an increase in the amount of GP-zone formation owing to the very high rate solidification after plasma-spraying. In the plasma-sprayed Al-Si/SiC composites GP zones were suppressed, since particle-matrix interfaces act as a sink for vacancies during quenching from high plasma process temperature. Introduction of SiC particles to the Al-Si age-hardenable alloy resulted in a decrease in the time required to reach plateau matrix hardness owing to acceleration of aging kinetics by ceramic SiC particles.     

An example of facade colour design of mass housing

The colours and architectural characteristics of building facades are the major factors affecting the general appearance of cities. When cities are examined from various perspectives, first impressions are obtained from the geometrical forms and facade colours of buildings. The facade colour arrangements should reflect the features of the region and buildings. In this context various features of natural and artificial environments such as plant life, water elements, climate, and historical texture should be examined, and a facade colour arrangement should be designed according to the examination results. In addition, the other factors effective in determining the colour and style of a building, such as social‐cultural background of the society and traditional and natural building materials, should not be forgotten because in some regions traditional buildings with special construction styles, materials, and colours create a specific identity for the settlements and cities. The aims of this article are to elucidate the colour contrast, colour arrangement, and colour design stages of mass housing and to explain the colour design of Bizimkent Mass Housing, which was constructed in a new dwelling zone in Istanbul, Turkey, as an example of such an arrangement. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 291–299, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10068     

Synthesis and investigation of optical properties of ZnS nanostructures

Structural characterizations of wurtzite zinc sulfide (ZnS) nanostructures synthesized by vapour–liquid–solid technique (VLS) were carried out by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. Spectral dependence of photoluminescence (PL) was also carried out for optical characterization. PL results indicate that the bandgap energy of bulk ZnS which is 3·68 eV at room temperature changes from 3·7 eV to 3·72 eV depending on the size of the structures. We also supported these results by calculating the bandgap energies theoretically with using the infinite potential well approximation for 1D structures.     

Effect of Lithium Enrichment on the Tritium Breeding Characteristics of Various Breeders in a Fusion Driven Hybrid Reactor

Selection of lithium containing materials is very important in the design of a deuterium–tritium (DT) fusion driven hybrid reactor in order to supply its tritium self-sufficiency. Tritium, an artificial isotope of hydrogen, can be produced in the blanket by using the neutron capture reactions of lithium in the coolants and/or blanket materials which consist of lithium. This study presents the effect of lithium-6 enrichment in the coolant of the reactor on the tritium breeding of the hybrid blanket. Various liquid–solid breeder couples were investigated to determine the effective breeders. Numerical results pointed out that the tritium production increased with increasing lithium-6 enrichment for all cases.     

Density functional modelling studies of chloride-substituted Schiff bases as corrosion inhibitors: Optimized geometries,atomic charges,solvent and non-linear optical effects

The anti-corrosive properties, optimized geometrical structures, atomic charges, molecular electrostatic potential (MEP) surfaces and non-linear optical (NLO) effects of some chloride-substituted Schiff bases salicylaldimine (R), N-(2-chlorophenyl)salicyaldimine (2Cl–R), N-(3-chlorophenyl)salicyaldimine (3Cl–R) and N-(4-chlorophenyl)salicyaldimine (4Cl–R) have been investigated by using density functional modelling calculations. The quantum chemical parameters, such as the highest occupied molecular orbital, the lowest unoccupied molecular orbital, gap energy and other parameters, including electronegativity, global hardness, the total charges on the whole molecules and the total energies have been calculated and discussed to obtain information about the relationships between the molecular and electronic structures of the studied inhibitors and their experimental corrosion inhibition efficiencies. The linear polarizability (α), and the firstorder hyperpolarizability (β) have been also predicted by the density functional theory (DFT) with different base sets 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) for investigating the effects of basis sets on the NLO properties.     

Drilling thick fabric woven CFRP laminates with double point angle drills

Carbon fiber reinforced plastics (CFRPs) have many desirable properties, including high strength-to-weight ratio, high stiffness-to-weight ratio, high corrosion resistance, and low thermal expansion. These properties make CFRP suitable for use in structural components for aerospace applications. Drilling is the most common machining process applied to CFRP laminates, and it is difficult due to the extremely abrasive nature of the carbon fibers and low thermal conductivity of CFRP. It is a challenge for manufacturers to drill CFRP materials without causing any delamination on the work part while also considering the economics of the process. The subject of this study is the drilling of fabric woven type CFRP laminates which are known to be more resistant to delamination than unidirectional type CFRP laminates. The objective of this study is to investigate the influence of double point angle drill geometry on drilling performance through an experimental approach. An uncoated carbide and two diamond coated carbide drills with different drill tip angles are employed in drilling experiments of aerospace quality thick fabric woven CFRP laminates. Force and torque measurements are used to investigate appropriate drilling conditions based on drill geometry and ideal drilling parameters are determined. Tool life tests of the drills were conducted and the condition of the diamond coating is examined as a function of drilling operational parameters. High feed rate drilling experiments are observed to be favorable in terms of drill wear. Feed is observed to be more important than speed, and the upper limit of feed is dictated by the drill design and the rigidity of the machine drill. Hole diameter variation due to drill wear is monitored to determine drill life. At high feeds, hole diameter tolerance is observed to be more critical than hole exit delamination during drilling of fabric woven CFRP laminates.     

Graph theoretical approach for automated IP lifecycle management in telco networks

IP address management (IPAM) systems are commonly used in the telecommunication industry to serve resource management for large-scaled IP networks. In resource management, IPAM provides network operators a live IP lifecycle support with an easier use on IP inventory while providing the scaling and high performance. Throughout the management of IP lifecycle, having up-to-date topology information plays a key role because of the rapidly changing usage of the IP addresses. Furthermore, if the usage information which corresponds to data taken from the real topology for a specific block does not match with the information in planned state, there arises an anomaly situation. And if this anomaly is not taken under control, especially for the large-scaled networks, it causes a considerable increase in the operational cost (OPEX) of the internet service providers (ISPs). Thus, keeping track of this resource and checking the anomaly cases make a smooth functioning process through the lifecycle of an IP block in telecom applications. However, the techniques used in traditional IPAMs are mostly not covering track of IP usage. For this purpose, we propose an attribute-based IP management module (KIP), which consists of three engines by covering the three active states of the IP lifecycle. In this way, KIP serves efficient IP management with minimum traversal time, anomaly rate, and planning time. Compared to previous methods, our method has addressed three additional challenges that significantly impact an effective IP lifecycle management by regarding device-specific information, such as connectivity, anomaly situation, and planning.     

Determination of Oil Content and Fatty Acid Composition of Sesame Mutants Suited for Intensive Management Conditions

Sesame mutants with closed capsules, determinate growth habit and wilt resistance, have been proposed to be suitable for intensive management conditions facilitating mechanized harvesting. The objective of our experiment was to determine the oil content and fatty acid composition of these mutants before they are placed on the market. Oil content and fatty acids were studied in 19 mutants, 6 breeding lines and 4 control source genotypes. The oil contents of the seeds ranged from 46.4 to 62.7%. The mutants had generally a lower oil content than the control genotypes except the wilting tolerant group. For unsaturated fatty acids, oleic acid was higher in the mutants and breeding lines while linoleic acid was lower in the seed oil. However, no mutants or breeding lines were found with radically different composition or with any undesirable lipid component. The closed capsule and determinate growth habit mutants need to be improved for oil content while their fatty acid composition is fine.