Direct tensile behavior of a transversely isotropic rock

The tensile behavior of a transversely isotropic rock is investigated by a series of direct tensile tests on cylindrical argillite specimens. To study the deformability of argillite under tension, two components of an electrically resistant type of strain gage with a parallel arrangement, or a semiconductor strain gage, are adopted for measuring the small transverse strain observed on specimens during testing. The curves of axial stress vs axial strain and vs average volumetric strain are presented for argillite specimens with differently inclined angles of foliation. Experimental results indicate that the stress-strain behavior depends on the foliation inclination of specimens with respect to the loading direction. The five elastic constants of argillite are calculated by measuring two cylindrical specimens in the manner recommended by Wei and Hudson. Based on theoretical analysis results, the range of the foliation inclination of the specimens tested is investigated for feasibility obtaining the five elastic moduli. A dipping angle of the foliations (θ) of 30–60° with respect to the plane normal to the loading direction is recommended. The final failure modes of the specimens are investigated in detail. A sawtoothed failure plane occurs for the specimens with a high inclination of foliation with respect to the plane perpendicular to the loading direction. On the other hand, a smooth plane occurs along the foliation for specimens with low inclination of foliation with respect to the plane normal to the loading direction. A conceptual failure criterion of tensile strength is proposed for specimens with a high inclination of foliation.     

Surface‐treatment effects of a sapphire substrate by He+‐, Ar+‐, and Xe+‐ion implantations for GaN epitaxial layers

Abstract— The structural, electrical, and optical properties of GaN epilayers grown on various ion‐implanted sapphire(0001) substrates by MOCVD were investigated. GaN or AlN buffer layers and pre‐treatment were indispensably introduced before GaN‐epilayer growth. The ion‐implanted substrate's surface had decreased internal free energies during the growth of the ion‐implanted sapphire(0001) substrates. The crystal and optical properties of the GaN epilayers grown in ion‐implanted sapphire(0001) substrates were improved. Also, an excessively roughened and modified surface caused by ions degraded the GaN epilayers. Not only the ionic radius but also the chemical species of implanted sapphire(0001) substrates improved the properties of the GaN epilayers grown by MOCVD. It is obvious that the ion‐implanted pre‐treatment of sapphire(0001) substrates can be an alternative pre‐treatment procedure for GaN deposition and has the potential to improve the properties of the GaN epilayers on sapphire(0001) substrates.     

Dispersion of Titania Powder in an Electronic Ink for Electrophoretic Display

The colloidal stability of titania powder in electronic ink, which contains an organic solvent of octane and a dispersant of phosphate ester, has been investigated. The concentration of phosphate ester required to stabilize the nonaqueous titania suspension agrees with that needed for monolayer adsorption. Theoretical calculations of potential energies show that the colloidal stability of organic titania suspension is caused by the steric repulsion mechanism. The results of optical properties including reflectivity and response time show that the resulting nonpolar titania suspension meets the requirements of an electronic ink for electrophoretic display.     

Experimental studies on the instabilities of viscous fingering in a Hele-Shaw cell

When air is injected into silicone oil contained in a horizontal Hele-Shaw cell, a single air bubble forms and grows showing various interesting phenomena. In this study the effects of the bubble front velocity, air injection velocity at a nozzle, fluid properties and cell depth on the stability of the growing bubble were investigated experimentally. By using the modified capillary number involving the aspect ratio, we obtained the onset conditions of the unstable bubble. Also, the bubble width was analyzed both quantitatively and qualitatively. Before the bubble experiences splitting, the bubble front velocity is almost proportional to the air injection velocity. Therefore the latter velocity may be used in a practical sense.     

Minimizing the total machine workload for the wafer probing scheduling problem

The Wafer Probing Scheduling Problem (WPSP) is a practical generalization of the parallel-machine scheduling problem, which has many real-world applications, particularly, in the Integrated Circuit (IC) manufacturing industry. In the wafer probing factories, the jobs are clustered by their product types, which must be processed on groups of identical parallel machines and be completed before the due dates. The job processing time depends on the product type, and the machine setup time is sequentially dependent on the orders of jobs processed. Since the wafer probing scheduling problem involves constraints on job clusters, job-cluster dependent processing time, due dates, machine capacity, and sequentially dependent setup time, it is more difficult to solve than the classical parallel-machine scheduling problem. In this paper, we consider the WPSP and formulate the WPSP as an integer programming problem to minimize the total machine workload. We demonstrate the applicability of the integer programming model by solving a real-world example taken from a wafer probing shop floor in an IC manufacturing factory.     

Synthesis of polycarbonate‐silica nanocomposites from copolymerization of CO2 with allyl glycidyl ether,cyclohexene oxide,and sol‐gel

The copolymerization of carbon dioxide, allyl glycidyl ether, and cyclohexene oxide catalyzed by the system consisting of Y(CF₃CO₂)₃, Zn(Et)₂, and pyrogallol in the solvent of 1, 3‐dioxolane was performed in this study. The IR, ¹H NMR, and ¹³C‐NMR spectra, as well as the elemental analysis, indicated that the resulting copolymer was an alternating polycarbonate possessing more than 90% of carbonate units. The molecular weight could be as high as 1.5 × 10⁵, and the polydispersity index was 4.5. The resultant polycarbonate was found to effectively react with 3‐(trimethoxysilyl)propyl methacrylate via a free radical reaction to result in a precursor used in the sol‐gel process to synthesize a polycarbonate‐silica nanocomposite. The nanocomposites were characterized by SEM, ²⁹Si NMR, TGA, DSC, and UV–Vis. Silica particles with size less than 100 nm were found to disperse uniformly in the nanocomposites. It was also found that the thermal properties were dependent on the content of cyclohexene carbonate units. Both the thermal and mechanical properties of the resultant nanocomposites could be adjusted with silica content, while the transparency was comparable to the base copolymer even at high silica contents. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 750–757, 2005     

A novel hybrid silica wide-band amplifier covering S+C+L bands with 105-nm bandwidth

We report a novel hybrid optical amplifier covering S+C+L bands with 105-nm total bandwidth using a silica fiber. The principle of amplification is based on the stimulated radiative transition of Er-ions for C-band and on the stimulated Raman scattering for S- and L-band, respectively. In this letter, we analyze the amplification characteristics for two types of active fiber mediums through numerical simulation. One is a silica fiber configured with Er-doped cladding and Ge-doped core and the other is a medium consisting of Er-doped fiber and dispersion-compensating fiber. By optimizing parameters such as fiber length and pump power, we newly achieve wide-band amplification with 105-nm bandwidth showing a flat gain characteristic over the entire S+C+L bands.     

Synthesis of a self-equalized dual-passband filter

This letter describes synthesis method for a self-equalized dual-passband filter. Compared to a conventional dual-passband filter, the self-equalized dual-passband filter can reduce bit-error rate (BER) in digital data communications and does not need an external equalizer for group delay equalization. To validate the synthesis method described in this letter, a 10-pole dual-passband filter which has two self-equalized five-pole elliptic-response passbands is synthesized.     

Reliability improvement by the suppression of keyhole generation in W-plug vias

This paper describes a mechanism of failures in W-plug vias due to the keyhole generation, and presents the process conditions which enhance the reliability of W-plug vias. For a high aspect ratio via-hole, one of the limiting factors in the reliability of the W-plug is the generation of the keyholes. We have investigated the sensitivities of corresponding technologies and conditions to the generation of the keyholes during the plug process. They include deposition technologies of TiN and deposition conditions of W. Based on the SEM observation and the electromigration failure test, the process conditions of TiN and W have been optimized.     

Suppression of transient phenomena in hybrid Raman/EDF amplifier

Transient phenomena of hybrid Raman/erbium-doped fiber amplifier (EDFA) upon optical channel add-drop are investigated. The transient responses of surviving channels are resulted from the combined dynamics of Raman amplifier and EDFA. It is shown that the suggested method employing fast gain control of EDFA only can effectively suppress the transient variation of output power. The transient-suppressing hybrid Raman/EDFA is proven to be enough for wavelength-division-multiplexing networks including reconfigurable optical add-drop multiplexer and/or transparent optical cross-connect, if the optical switching speed is carefully chosen.