Residual toughness of poly(acrylonitrile-butadiene-styrene) (ABS) after fatigue loading—effect of uniaxial fatigue loading

Toughness variation of non-notched poly(acrylonitrile-butadiene-styrene) (ABS) subjected to uniaxial fatigue loading was investigated. The experiments were conducted by applying fatigue loading to strip specimens first, from which dog-bone specimens were machined. The dog-bone specimens were tested to measure the strain for the on-set of fracture, named cracking strain here, thus to monitor the toughness change due to the fatigue loading.The test results showed that the fatigue loading caused the toughness drop in ABS, even before any visible crack was developed. Damage development and fracture behavior were then analyzed using scanning electron microscopy (SEM). The SEM analysis revealed that damage zones, not cracks, were initiated during the fatigue loading, and were the main cause of the toughness drop. Mechanisms for the damage initiation include matrix crazing and debonding of small rubber particles; however, large rubber particles remained intact. Based on the results, a deformation model is proposed for the damage zone initiation, which provides an explanation for the toughness change under the fatigue loading.     

Broadly wavelength-tunable external cavity lasers with extremely low power variation over tuning range

Tunable external-cavity lasers with low power variation over a broad tuning range are demonstrated using asymmetric multiple quantum-wells with a wide and flat gain. For a 2.8-/spl mu/m-wide ridge waveguide laser of cavity length 380 /spl mu/m, when used in a grating external cavity and with an antireflection coating on one facet of laser diode chip, the power variation of less than -1 dB is obtained over a range of 80 nm. This extremely low power variation is a direct result of the spectrally flat gain.     

W-band divide-by-3 frequency divider using 0.1 /spl mu/m InAlAs/InGaAs metamorphic HEMT technology

A W-band divide-by-3 frequency divider with wide bandwidth and low power dissipation is presented using harmonic injection-locking technique. A cascode FET is employed for a self-oscillating second-harmonic mixer which is injection-locked by third-harmonic input to obtain the division order of three. The fabricated frequency divider using 0.1 /spl mu/m GaAs metamorphic HEMT technology shows superior performance such as large bandwidth of 6.1 GHz around 83.1 GHz (7.3%) under small DC power consumption of 12 mW.     

2/spl times/4 optical add-drop module with no difference in propagation length

We developed a micromachined X-type 2/spl times/4 optical add-drop module (OADM) featuring no difference in propagation length. Four pairs of lensed fibers are aligned in "X" position, and four micromirrors are located between the pairs of optical fibers. The OADM was fabricated utilizing a silicon-on-insulator process. Electrostatic comb actuators can be driven up to 90 /spl mu/m to change the light path within 1 ms. The insertion loss and the on-off ratio were less than 3 and 70 dB, respectively. The loss uniformity in every channel was 1.5 dB.     

Performance modeling and evaluation of data/voice services in wireless networks

Application-level performance is a key to the adoption and success of the CDMA 2000. To predict this performance in advance, a detailed end-to-end simulation model of a CDMA network is built to include application traffic characteristics, network architecture, network element details using the proposed simulation methodology. We assess the user-perceived application performance when a RAN and a CN adopt different transport architectures such as ATM and IP. To evaluate the user-perceived quality of voice service, we compare the end-to-end packet delay for different vocoder schemes such as G.711, G.726 (PCM), G.726 (ADPCM), and vocoder bypass scheme. By the simulation results, the vocoder bypass scenario shows 30% performance improvement over the others. We also compare the quality of voice service with and without DPS scheduling scheme. We know that DPS scheme keep the voice delay bound even if the service traffic is high. For data packet performance, HTTP v.1.1 shows better performance than that of HTTP v.1.0 due to the pipelining and TCP persistent connection. We may conclude that IP transport technology is better solution for higher FER environment since the packet overhead of IP is smaller than that of ATM for web browsing data traffic, while it shows opposite effect to the small size voice packet in RAN architecture. We show that the 3G-1X EV-DO system gives much better packet delay performance than 3G-1X RTT. The main conclusion is that end-to-end application-level performance is affected by various elements and layers of the network and thus it must be considered in all phases of the development process. Jae-Hyun Kim He received the B.S., M.S., and Ph.D. degrees, all in computer science and engineering, from Hanyang University, Ansan, Korea, in 1991, 1993, and 1996 respectively. In 1996, he was with the Communication Research Laboratory, Tokyo, Japan, as a Visiting Scholar. From April 1997 to October 1998, he was a post-doctoral fellow at the department of electrical engineering, University of California, Los Angeles. From November 1998 to February 2003, he worked as a member of technical staff in Performance Modeling and QoS management department, Bell laboratories, Lucent Technologies, Holmdel, NJ. He has been with the department of electrical engineering, Ajou University, Suwon, Korea, as an assistant professor since 2003. His research interests include QoS issues and cross layer optimization for high-speed wireless communication. Dr. Kim was the recipient of the LGIC Thesis Prize and Samsung Human-Tech Thesis Prize in 1993 and 1997, respectively. He is a member of the Korean Institute of Communication Sciences (KICS), Korea Institute of Telematics and Electronis (KITE), Korea Information Science Society (KISS), and IEEE. Hyun-Jin Lee received the B.S. degree in electrical engineering from Ajou University, Suwon, Korea, in 2004, and is working toward the M.S. degree and Ph. D. degree in electrical engineering at Ajou University. He has been awarded Samsung Human-Tech Thesis Prize in 2004. His research interests QoS, especially network optimization and wireless packet scheduling. He is a member of the KICS. Sung-Min Oh received the B.S. and M. S. degrees in electrical engineering form Ajou University, Suwon, Korea, in 2004, and is working toward the Ph. D. degree in electrical engineering at Ajou University. His research interests QoS performance analysis and 4G network. He is a member of the KICS. Sung-Hyun Cho received his B.S., M.S., and Ph.D. in computer science and engineering from Hanyang University, Korea, in 1995, 1997, and 2001, respectively. From 2001 to 2005, he has been with Samsung Advanced Institute of Technology, where he has been engaged in the design and standardization of MAC and upper layers of B3G, IEEE 802.16e, and WiBro systems. He is currently a MAC part leader in the telecommunication R&D center of Samsung Electronics. His research interests include 4G air interface design, radio resource management, cross layer design, and handoff in wireless systems.     

Instability of solid–liquid interface in transitional metal–carbide systems

The instability of solid–liquid interface (ISLI) during the liquid-phase sintering was studied using carbide–Ni composites. Of the various transitional metal carbides TiC of 4th period is the only carbide that exhibits a strong ISLI with negative curvatures in molten Ni. No ISLI was observed for other carbides in the 5th and 6th periods. The origin of ISLI is strain developed at the interface between the carbides and the newly formed solid solutions. The difference in the size of the atoms involved can be used to predict the formation of a carbide–Ni solid solution when the Hume-Rothery rules are applied. Aside from the size factor, other factors in the rules are not effective in predicting this phenomenon.     

Kernel Spectral Matched Filter for Hyperspectral Imagery

In this paper a kernel-based nonlinear spectral matched filter is introduced for target detection in hyperspectral imagery, which is implemented by using the ideas in kernel-based learning theory. A spectral matched filter is defined in a feature space of high dimensionality, which is implicitly generated by a nonlinear mapping associated with a kernel function. A kernel version of the matched filter is derived by expressing the spectral matched filter in terms of the vector dot products form and replacing each dot product with a kernel function using the so called kernel trick property of the Mercer kernels. The proposed kernel spectral matched filter is equivalent to a nonlinear matched filter in the original input space, which is capable of generating nonlinear decision boundaries. The kernel version of the linear spectral matched filter is implemented and simulation results on hyperspectral imagery show that the kernel spectral matched filter outperforms the conventional linear matched filter.     

Reduction of optical beat interference using gain-saturated RSOA in upstream WDM/SCM optical links

A new scheme for reducing optical beat interference (OBI) noise in optical network units is proposed for subcarrier multiplexing-based access network applications. The optical spectrum of the transmit lasers is broadened by using a radio frequency (RF) clipping tone with a modulation depth greater than one. This reduces the impact of the OBI noise. The distortions caused by an RF clipping tone are also suppressed by introducing a gain-saturated reflective optical amplifier, which shows the characteristics of high-pass filter. The proposed scheme has been verified by measuring the error vector magnitude of 16QAM signal with 20 Mbps. Error-free transmission has been achieved even when the light of OBI-noise-causing lasers is stronger than that of the signal laser by 7 dB     

Reversible energy recovery logic circuit without non-adiabaticenergy loss

The authors propose a reversible energy recovery logic (RERL) circuit for ultra-low-energy consumption, which consumes only adiabatic energy loss and leakage current loss by completely eliminating non-adiabatic energy loss. It is a dual-rail adiabatic circuit using the concept of reversible logic with a new eight-phase clocking scheme. Simulation results show that at low-speed operation, the RERL consumes much less energy than the complementary static CMOS circuit and other adiabatic logic circuits     

Numerical simulation of flying phenomena of the running tape on rotating drum

This paper analyzes the running mechanism of flexible and thin tape above rotating protrusion through a numerical simulation. The scope of analysis is confined to the phenomena of elastohydrodynamic lubrication between the rotating drum with a protrusion and the running tape. This model is based on the modified Reynolds equation and the equation of plate considering the effect of geometric nonlinearity and geometry of protrusion. Finite element method of Bubnov-Galerkin type is adopted as a numerical simulation technique to solve the above two coupled nonlinear equations. In numerical simulation, the influences of tape tension and protrusion velocity are evaluated in simple model. In complex models, the reciprocal action of two protrusions is simulated.