Fabrication of Al/AlN composites by in situ reaction

The tensile properties and microstructures of various Al alloys fabricated by the pressureless infiltration method under a nitrogen atmosphere were examined. The spontaneous infiltration of molten metal into the powder bed occurred at 800 °C for 1 h under a nitrogen atmosphere. As a result, it was possible to fabricate Al alloys reinforced with AlN particles formed by in situ reaction. A significant strengthening even in the control alloy occurred due to the formation of in situ AlN particle even without an addition of artificial reinforcement. Strength values of the control alloy were increased with decreasing Al powders in bottom powders bed. In addition, tensile strength in Al–Mg alloys was increased with Mg content.     

The Transfer of Fibres in the Carding Machine

The problem of understanding the transfer of fibres between carding-machine surfaces is addressed by considering the movement of a single fibre in an airflow. The structure of the aerodynamic flow field predicts how and when fibres migrate between the different process surfaces. In the case of a revolving-flats carding machine the theory predicts a “strong” aerodynamic mechanism between taker-in and cylinder and a “weak” mechanism between cylinder and removal cylinder resulting in effective transfer in the first case and a more limited transfer in the second.     

Effects of numerical formulation on magnetic field computation using meshless methods

Meshless methods have some advantages over their counterparts such as the finite-element method (FEM). However, existing meshless methods for computational electromagnetic fields are still not as efficient as FEM. In this paper, we compare two meshless methods of discretizing the computational domain of Poisson-like problems; namely, the point collocation and Galerkin methods (which use the strong and weak forms of the governing equation respectively), and their effects on the computational accuracy and efficiency of the magnetic fields. We also discuss methods of handling discontinuities at the material interface. We present several examples, which also provide a means to validate and evaluate both meshless methods. Exact solutions and/or FEM are used as a basis for comparison. In addition, we also verify the results by comparing computed magnetic forces against those measured experimentally.     

Analysis of the Optimum Configuration of Roadside Units and Onboard Units in Dedicated Short-Range Communication Systems

With the aid of a simple relation, which is analogous to the radar equation, the uplink signal strength received by the receiving module of a roadside unit (RSU) and emitted from the radiation module of an onboard unit (OBU) can be described. Setting the scale of this relation arbitrarily and determining the signal strength threshold from experimental measurements, and combined with the simulation of the radiation and the receiving pattern by cosineⁿ function, the relative signal strength emitted from the OBU and received by the RSU can be calculated successfully. From this computed relative signal strength and the threshold, the influence of the RSU and OBU mounting parameters, such as the mounting angles and mounting height, on the available communication region is analyzed. The effect of windshield fading is also considered. With the help of the analysis results, an optimum RSU and OBU mounting configuration can be easily obtained. This method can be used conveniently and successfully for very short wavelengths. This includes visible light, infrared, and even submillimeter-wave ranges. For millimeter-wave and microwave systems, this method can, in some cases, also provide a rudimentary estimation     

Improvement in the volume efficiency of multilayered ceramic capacitors (MLCCs)

An attempt was made to improve the conventional lamination process in the multilayered ceramic capacitors (MLCCs) fabrication by adapting a solvent treatment on the BaTiO₃ green sheets. During the lamination process, additional particle rearrangement in the BaTiO₃ green block was stimulated by solvent treatment. This rearrangement resulted in a more compact structure of the BaTiO₃ green sheets compared to that obtained through the conventional lamination process. The overall thickness of BaTiO₃/Ni/BaTiO₃ laminates was also reduced after solvent treatment. It is suggested that miniaturization in the fabrication of MLCCs can be improved by adapting a solvent treatment during the lamination process.     

Preparation of lithium-ion polymer battery using LiNi1/3Co1/3Mn1/3O2 as a cathode material and its electrochemical properties

In this work, LiNi_1/3Mn_1/3Co_1/3O₂ powders were synthesized from co-precipitated spherical metal hydroxide. In the voltage range of 2.8–4.2, 2.8–4.4, and 2.8–4.6 V, the discharge capacities of LiNi_1/3Mn_1/3Co_1/3O₂ electrode were 163, 177, and 193 mAh⋅g⁻¹, respectively. A gel polymer electrolyte (GPE) was also prepared using polyoxyalkylene glycol acrylate (POAGA) as a macromonomer. LiNi_1/3Mn_1/3Co_1/3O₂/GPE/graphite cells were prepared and their electrochemical properties were evaluated at various current densities and temperatures. The ionic conductivity of the GPE was more than 6.2 × 10⁻³ S⋅cm⁻¹ at room temperature. POAGA-based cells were showed good electrochemical performances such as rate capability, low-temperature performance, and cycleability.     

Preparation of SnO2 whiskers via the decomposition of tin oxalate

A new method for preparing SnO₂ whiskers by the decomposition of SnC₂O₄ is suggested. A Whisker-like morphology of a SnC₂O₄ precipitate was attained via the gradual addition of an oxalic acid solution to a hot SnCl₂ aqueous solution (T > 50^∘C). In comparison, when the solution temperature was either lower than 50^∘C or when ethanol was used as the solvent, the SnC₂O₄ precipitate showed an angular and relatively isotropic morphology. The morphology of the SnC₂O₄ precipitate remained even after its thermal decomposition into SnO₂ at 400^∘C indicating that SnC₂O₄ precipitation is a key step in preparing the whiskers. The formation mechanism of SnO₂ whiskers was explained by the supersaturation during the precipitation of SnC₂O₄.     

A novel frequency-offset monitoring technique for direct-detection DPSK systems

We propose and demonstrate a novel technique to monitor the frequency offset between the optical source and delay interferometer (DI) for direct-detection differential phase-shift-keying (DPSK) systems. In this scheme, a phase-modulated tone is applied to DPSK signals at the transmitter and then detected after being converted into an amplitude-modulated tone at the DI to be used for the monitoring signal. Our experimental demonstration shows that the monitoring range and sensitivity of the proposed scheme are measured to be /spl plusmn/2 GHz and /spl sim/10 MHz, respectively, which we believe are good enough to be used either to generate alarm signals for the frequency offset monitoring or to control the feedback loop of the DI.     

An all-optical 2R regenerator using a compact self-seeded Fabry-Pe/spl acute/rot laser diode incorporated in a bidirectional EDFA

An all-optical 2R regenerator, based on a compact self-seeded Fabry-Pe/spl acute/rot laser diode with a 10-mm-long embedded fiber Bragg grating cavity, and a bidirectional erbium-doped fiber amplifier, is proposed and experimentally demonstrated to execute all-optical 2R regeneration at 10 Gb/s. Compared with the conventional 1R regeneration, the proposed scheme has achieved significant 6.4-dB improvement of power penalty at bit-error ratio =10/sup -9/ in the transmission experiment over 100-km standard single-mode fiber.