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Abstract:: Comparative study of the solid-state reaction (SSR) in a series of Ti/Ni multilayered films (MLF) with a bilayer period of 0.65-22.2 nm and a constant Ti to Ni sublayer thickness ratio has been performed by using the experimental and computer-simulated magneto-optical (MO) and optical spectroscopies as well as X-ray diffraction (XRD). It was shown that alloyed-like regions in an amorphous structure is spontaneously formed near the interfaces between pure elements during the film deposition. The thickness of this region was estimated as 2-3.8 nm on the basis of the MO and optical studies. The SSR in the Ti/Ni MLF caused by an annealing at 580 K for 60 min increases the thickness of these interfacial amorphous regions. It was shown that SSR takes place mainly in the Ti/Ni MLF with relatively “thick” sublayers. The existence of a threshold nominal Ni-sublayer thickness for observing the equatorial Kerr effect of about 3.0 and 4.5 nm for the as-deposited and annealed Ti/Ni MLF, respectively, is explained by formation of the nonmagnetic alloyed regions between pure components during the film deposition as a result of the SSR. For the case of Ti/Ni MLF, the MO and optical approaches turn out to be more sensitive in determining the thickness of the reacted zone, while XRD is more useful for the structural analysis. It was also shown that the very thin nonreacted Ni sublayers have different MO properties (and hence electronic structure) from the bulk.

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A theoretical and experimental study was performed to examine the water spray method of ice slurry production. First, the conditions for the formation of ice particles were investigated theoretically by the diffusion-controlled evaporation model. The prediction of the model was proved to agree relatively well with experiments in which we examined the conditions for a droplet of initial temperature 20°C and size 50 μm to change into an ice particle in a chamber of height 1.33 m. Second, the production of cold storage heat will increase almost proportionally to the number of spray nozzles because no substantial difference was found in the Sauter Mean Diameter (SMD) of sprays from single and twin nozzle. Third, an ice slurry was experimentally obtained by spraying droplets of 7% ethylene glycol aqueous solution in a vacuum chamber where pressure is maintained below the freezing point of the solution. Finally, based on the theoretical and experimental results, we propose an optimizing chart for providing the operating conditions to make ice slurry using the relations of the staying time of the droplet in the chamber, the injection pressure, the spray droplet size and the chamber pressure.

Abstract:: The influence of the structural disorder on the electron transport properties of Co0.50Ti0.50 alloy films in a temperature range of 4.2-300 K has been investigated at zero and 0.5 T of magnetic field. The disordered state in the alloy films was obtained by vapor quenching deposition onto substrates cooled by liquid nitrogen. The changes in the transport properties of the alloy films caused by the order-disorder structural transformation and the external magnetic field are explained by the analyses using various models for the electron transport in the disordered systems.

The most critical step in a tolerance chart is to determine the various unknown working dimensions and their corresponding tolerances that are related to a particular blueprint dimension. The required algorithm in doing so in manual tolerance charting is both tedious and time–consuming. This paper presents a simple path tracing model that is used to achieve the above–mentioned. From this model, the unknown working dimensions and their corresponding blueprint dimensions are reduced to a set of linear equations. All the working dimensions can be easily solved by employing the Gauss elimination technique. Next, the tolerances are balanced using a separate mathematical model. As a result, the complete system is capable of solving all the unknown working dimensions involved in a machining process and obtaining their respective optimised tolerances.

Electrochemical synthesis of millimeter-sized single crystals of Ba1−ϰKϰBio3with superconducting transition temperatures of 31.0 K is detailed. The resulting crystals are cubic, well-faceted and exhibit remarkably high quality surfaces which aid in important studies of the transport properties of the material. In addition, an oxygenation treatment which increases and sharpens the transition temperature of the as-grown crystals is reported.

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Acoustic wave generation during excimer laser interaction with copper substrates has been investigated. It is found that the amplitudes of acoustic waves depend on laser fluence, pulse number and surface condition of the substrate and can be used to determine the nature of laser-material interactions such as pulsed-laser-induced cleaning, surface roughening and ablation. When laser fluence is below the ablation threshold of copper, the amplitudes are reduced to zero due to the cleaning of surface contaminants but increase again due to surface roughening if the fluence is large enough. As laser fluence becomes higher than the ablation threshold, the amplitudes of acoustic waves also reduce with increasing pulse number but to a level larger than zero due to laser ablation and then increase again due to surface morphology change. By establishing a relationship between the amplitudes and laser-substrate parameters, i.e., bulk response, surface response, pulse dependence and morphology response, a numerical formula is proposed for real-time monitoring of laser-solid interaction. The bulk response can be used to determine the ablation threshold. The morphology response is found to reach the maximum at the ablation threshold.