Utilization of self-injection Fabry–Perot laser diode for long-reach WDM-PON

In this investigation we propose and demonstrate a wavelength widely tunable laser source employing a self-injected Fabry–Perot laser diode (FP-LD) for long-reach wavelength-division-multiplexed passive optical network (WDM-PON). By using a tunable bandpass filter and an optical circulator inside the gain cavity, a stable and single-longitudinal-mode (SLM) laser output is achieved. Besides, the proposed laser sources are directly modulated at 2.5 Gb/s for both downlink and uplink transmissions of 85 km single mode fiber (SMF) in PON without dispersion compensation.     

Integration of four-phase QFD and TRIZ in product R&D: a notebook case study

Worldwide demand for notebook computers has outstripped that for desktop computers. Today, notebook computer design and manufacturing is one of the most competitive of all electronic industry subsectors. Innovation and environmental friendliness (i.e., “green”) are both of increasing importance to notebook computer makers. Traditional strategies for NB design and manufacturing may be inadequate to meet steadily rising customer product expectations and environmental concerns. This study aimed to develop and market an environmentally friendly and energy-efficient notebook computer. A four-phase QFD plan, based on a series of matrices, was developed to create an innovative product that (1) satisfied customer needs, (2) fulfilled target specifications, (3) achieved target cost objectives, (4) was achievable within a set development timetable and (5) realized high production yields. Contradictions among plan objectives represent a threat to overall project success. This study identified major QFD contradictions in the spheres of engineering and administration and applied a methodology integrating TRIZ inventive principles, a contradiction matrix, and eco-efficiency elements to achieve green-design solutions.     

Bipolar switching characteristics of low-power Geo resistive memory

We reported an ultra low-power resistive random access memory (RRAM) combining a low-cost Ni electrode and covalent-bond GeO_x dielectric. This cost-effective Ni/GeO_x/TaN RRAM device has very small set power of 2 μW, ultra-low reset power of 130 pW, greater than 1 order of magnitude resistance window, and stable retention at 85 °C. The current flow at low-resistance state is governed by Poole-Frenkel conduction with electrons hopping via defect traps, which is quite different from the filament conduction in metal-oxide RRAM.     

A New Union Bound on the Error Probability of Binary Coded OFDM Systems in Wireless Environments

Orthogonal Frequency Division Multiplexing (OFDM) systems are commonly used to mitigate frequency-selective multipath fading and provide high-speed data transmission. In this paper, we derive new union bounds on the error probability of a coded OFDM system in wireless environments. In particular, we consider convolutionally coded OFDM systems employing single and multiple transmit antennas over correlated block fading (CBF) channels with perfect channel state information (CSI). Results show that the new union bound is tight to simulation results. In addition, the bound accurately captures the effect of the correlation between sub-carriers channels. It is shown that as the channel becomes more frequency-selective, the performance get better due to the increased frequency diversity. Moreover, the bound also captures the effect of multi-antenna as space diversity. The proposed bounds can be applied for coded OFDM systems employing different coding schemes over different channel models.     

Cryptanalysis of Hsiang‐Shih's authentication scheme for multi‐server architecture

From user point of view, password‐based remote user authentication technique is one of the most convenient and easy‐to‐use mechanisms to provide necessary security on system access. As the number of computer crimes in modern cyberspace has increased dramatically, the robustness of password‐based authentication schemes has been investigated by industries and organizations in recent years. In this paper, a well‐designed password‐based authentication protocol for multi‐server communication environment, introduced by Hsiang and Shih, is evaluated. Our security analysis indicates that their scheme is insecure against session key disclosure, server spoofing attack, and replay attack and behavior denial. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of sintering atmosphere on the microstructure and water durability of SnO–MgO–P<Subscript>2</Subscript>O<Subscript>5</Subscript> glass

Effects of sintering atmosphere (Ar, air, and O₂) on the sinterability and crystallization at 380–470 °C of 60SnO, 10MgO, 30P₂O₅ (mol%) glass powder, and the water durability of the sintered glass were investigated. Increasing the oxygen partial pressure (P_\textO2 ) (P_{{{\text{O}}_{2} }} ) in the sintering atmosphere enhanced the oxidation tendency of Sn²⁺ to Sn⁴⁺ near the surface region of the glass particles. Therefore, the glass viscosity was increased, resulting in the increase in both the temperature of densification and the temperature at which crystalline phases developed. Phase assemblage and the amounts of crystalline phases were also affected by P_\textO2 . P_{{{\text{O}}_{2} }} . The water durability of the sintered glasses is discussed in terms of the above microstructural parameters.     

Surface states related the bias stability of amorphous In–Ga–Zn–O thin film transistors under different ambient gasses

This paper investigates the origin of the bias stability under ambient gas (oxygen, moisture and vacuum) of In–Ga–Zn–O thin film transistors with different annealing temperatures. In Zn-based TFTs, the electrical characteristic of device is a strongly function with the ambient gas, the simultaneous gas ambient and bias stresses are applied on devices annealed in atmosphere ambient to study this issue. The result shows the device which is annealed at temperature up to 330 °C has worst reliability. We suppose that the sensitivity of gas ambient depend the defect state, which is associated to the annealing temperature, of surface in a-IGZO.     

Two-dimensional simulations of ion concentration distribution in microstructural electroforming

A theoretical model is constructed to predict the metal ion concentration distribution during the electroforming of high-aspect-ratio microstructures. Two-dimensional numerical simulations are then performed using COMSOL Multiphysics^TM software to investigate the effect of the processing conditions and the microstructure geometry on the electroforming results. The electroforming outcome is significantly dependent upon the current density and the microstructure aspect ratio, respectively. The simulation results for the electroforming of microstructural posts with an aspect ratio of 10:1 are found to be in good agreement with the analytical solutions.     

Synergetic effects of temperature and magnetic field on the aragonite and calcite growth

The effects of temperature and magnetic field on aragonite and calcite growth were investigated in a stirred-tank crystallizer, using the constant-composition technique. At room temperature without magnetization, the calcite seeds grew but the aragonite did not. When the growth rates of the aragonite and calcite seeds were measured in the presence of a magnetic field at temperatures above room temperature, the synergetic effects were significant but with differing effects on the different seeds. The cluster-transformation mechanism was used to explain the growth rate data. Finally, the aragonite growth rate data were compared with data obtained in a fluidized bed.     

Drawing and tensile properties of polyamide 6/calcium chloride composite fibers

The influence of calcium chloride (CaCl₂) contents on the drawing and tensile properties of polyamide 6 (PA6)/CaCl₂ composite fibers prepared at varying drawing temperatures were investigated. At any fixed drawing temperature, the achievable draw ratio (D_ra) values of PA6_x(CaCl₂)_y as-spun fiber specimens approach a maximum value, as their CaCl₂ contents are close to the 3 wt% optimum value. The maximum D_ra values obtained for PA6_x(CaCl₂)_y as-spun fiber specimens prepared at the optimum CaCl₂ content reach another maximum as their drawing temperatures approach the optimum drawing temperature at 120 °C. The initial modulus, tensile strength and birefringence values of the PA6 and PA6_x(CaCl₂)_y fiber specimens were found to improve consistently with D_ra or with drawing temperatures when they were stretched to a fixed D_ra. Similar to those found for their achievable drawing properties, the ultimate initial modulus, tensile strength and birefringence values of PA6_x(CaCl₂)_y fiber specimens approach a maximum value, as their CaCl₂ contents and drawing temperatures approach the 3 wt% and 120 °C optimum values, respectively. Experiments including thermal, FTIR, melt shear viscosity and wide angle X-ray diffraction experiments were performed on the PA6_x(CaCl₂)_y resin and/or fiber specimens to clarify the possible reasons accounting for the interesting drawing, tensile and birefringence properties found for the PA6_x(CaCl₂)_y fiber specimens.