Novel gain monitoring scheme in Remotely-Pumped EDF/DRA hybrid inline amplifier is proposed using Optical Time Domain Reflectometer (OTDR). Signal degradation due to cross gain modulation (XGM) caused by an OTDR pulse in the distributed Raman amplifier (DRA) section and remotely-pumped EDF (RP-EDF) unit is analyzed theoretically. The required conditions for suppressing of XGM in the DRA section are derived. We propose the directional bypass configuration to realize OTDR measurement without XGM in the EDF unit. Transmission experiments using the RP-EDF/DRA hybrid inline amplifier demonstrate the absence of transmission impairement induced by OTDR. An analysis of the OTDR trace for each gain medium is also discussed. The theoretical analysis agrees well with the experimental result.

For wavelength conversion based on cross-gain modulation (XGM) and cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), a CW assist light is quite effective for acceleration of carrier recovery and reduction of pattern effects. We theoretically study assist light conditions both for XGM- and XPM-based wavelength conversion by numerically simulating eye-diagrams. Taking into account the spatial and temporal variations of carrier density along the SOA length, we successfully clarify the dependences of wavelength, power, and propagation direction of the assist light, and reveal the principal difference of response characteristics between XGM and XPM depending on carrier modulation.

This paper discusses the design, fabrication, and measurement of four L-shaped-slot microstrip patch antenna for HiperLan2. The prototype consists of four L-shaped slots. To obtain suitable bandwidth, the form layer is inserted between the ground plane and substrate. The design considers various important factors that include the four L-slot's length, width, position, air-gap height, and feed-point position. Once these factors are optimized, a four L-shaped slot microstrip patch antenna is fabricated and measured. The measured results of the fabricated four L-shaped slot antenna are as follows: resonant frequency is 5.35 GHz, bandwidth is approximately 8.1% (VSWR < 2.0), and gain is 8-9 dBi. The experimental far-field patterns are stable across the pass band. The 3 dB bandwidth in Elevation and Azimuth are 69and 62, respectively.

This paper presents an analytical model for the electromagnetic radiation in multi-microstrip lines covering the frequency range from 30 MHz to 1 GHz. The radiated emissions of multi-microstrip structure can be divided into the summation of radiated emissions of multi-individual microstrip structures. It is done by modelling the imperfect ground effect of the PCBs. Here we present a circuit model based on traditional transmission lines (TMLs) model. For more accurate analysis of the imperfect ground effect in multi-microstrip lines, we will divide the equivalent circuit model into N sections, based on transverse electromagnetic (TEM) assumption, to estimate the electromagnetic interference (EMI) of multi-microstrip lines. The quantitative value of induced current distribution along the ground return path depends on the physical size, geometry and length of ground trace. Measured data are presented to confirm the results of numerical analysis and the computer simulations with a software package based on the Finite Element Method. A knowledge of EMI source mechanism and their relationship to layout geometries is necessary to determine the essential features that must be modelled to estimate emissions in PCBs design.

In this paper a novel dielectric resonator (DR) bandpass filter (BPF) with flexible arrangement of attenuation poles is proposed. This DR filter is similar to a conventional DR filter except adding a microstrip line below a DR, which not only shifts the location of attenuation poles, but also improves skirt characteristics. The duplexer with the proposed DR BPF has been yielded better isolation and sharper skirt behavior than that with a conventional DR filter. The implemented duplexer has shown a good performance and been well agreed with the simulation.

We analyzed passivation film and the AlGaN surface states using open-gated structures of AlGaN/GaN HFETs by numerical simulation and experiments. From the analyses, we confirmed that insulating film conductivity plays the prominent roles in device performances of the wide bandgap semiconductor device. Device simulation confirmed that the difference in ID-VG characteristics is due to the trapping type of the surface states; electron-trap type or hole-trap type. For electron-trap type surface states, the surface potential pinned at electron quasi-Fermi level, which is the same as the channel potential in the open-gated FETs. As a result, surface potential of ungated region is equal to the channel electric potential resulting in the uncontrollability of the channel current by the edge placed gate electrode. For hole-trap type surface states, the surface potential is pinned at hole quasi-Fermi level, which must be the same as the edge placed gate electrode potential. Then, the AlGaN surface potential varies with the electrode potential variation allowing the control of channel current as if the whole channel is covered with a metal electrode. Experiments for open-gated FET with unpassivated surface show no current variation. This corresponds to electron-trap type surface states from the simulation. On the other hand, SiOX evaporated open-gated FET show current control by the gate electrode. The ID-VG characteristics resembles in simulated ID-VG characteristics with hole-trap surface states. However, the estimated time constants for the trap reactions are incredibly long due to the deep energy level for the surface states in wide bandgap semiconductors. In addition, the open-gated FET showed reverse threshold shift to the value expected from the hole-trap pinning levels. So, we concluded that the no current variation for the unpassivated open-gated FET can be attributed to electron traps in the surface states, but the control of the drain current for SiOX deposited open-gated FET is not by surface hole-traps, but by slightly conductive passivation film of SiOX.

Synthetic speech usually suffers from bad F0 contour surface. The prediction of the underlying pitch targets robustly relies on the quality of the predicted prosodic structures, i.e. the corresponding sequences of tones and breaks. In the present work, we have utilized a linguistically enriched annotated corpus to build data-driven models for predicting prosodic structures with increased accuracy. We have then used a linear regression approach for the F0 modeling. An appropriate XML annotation scheme has been introduced to encode syntax, grammar, new or already given information, phrase subject/object information, as well as rhetorical elements in the corpus, by exploiting a Natural Language Generator (NLG) system. To prove the benefits from the introduction of the enriched input meta-information, we first show that while tone and break CART predictors have high accuracy when standing alone (92.35% for breaks, 87.76% for accents and 99.03% for endtones), their application in the TtS chain degrades the Linear Regression pitch target model. On the other hand, the enriched linguistic meta-information minimizes errors of models leading to a more natural F0 surface. Both objective and subjective evaluation were adopted for the intonation contours by taking into account the propagated errors introduced by each model in the synthesis chain.

A waveguide crossed-slot linear array with a matching element is accurately analyzed and designed by the method of moments using numerical-eigenmode basis functions developed by the authors. The rounded ends of crossed-slots are accurately modeled in the analysis. The initial values of the slot parameters determined by a model with assumption of periodicity of field are modified and refined by the full-wave finite-array analysis for uniform excitation and small axial ratio. As an example, an 8-element linear array is designed at 11.85 GHz, which radiates a circularly polarized wave at a beam-tilting angle of 50 degrees. The radiation pattern, the frequency characteristics of the reflection and the axial ratio are compared between the analysis and the measurement and they agree very well. The calculated and measured axial ratio at the beam direction are 0.1 dB and 1.7 dB, respectively. This method provides a basic and powerful design tool for slotted waveguide arrays.

This research aims to construct a high-quality Japanese TTS (Text-to-Speech) system that has high flexibility in treating prosody. Many TTS systems have implemented a prosody control system but such systems have been fundamentally designed to output speech with a standard pitch and speech rate. In this study, we employ a unit selection-concatenation method and also introduce an analysis-synthesis process to provide precisely controlled prosody in output speech. Speech quality degrades in proportion to the amount of prosody modification, therefore a target cost for prosody is set to evaluate prosodic difference between target prosody and speech candidates in such a unit selection system. However, the conventional cost ignores the original prosody of speech segments, although it is assumed that the quality deterioration tendency varies in relation to the pitch or speech rate of original speech. In this paper, we propose a novel cost function design based on the prosody of speech segments. First, we recorded nine databases of Japanese speech with different prosodic characteristics. Then with respect to the speech databases, we investigated the relationships between the amount of prosody modification and the perceptual degradation. The results indicate that the tendency of perceptual degradation differs according to the prosodic features of the original speech. On the basis of these results, we propose a new cost function design, which changes a cost function according to the prosody of a speech database. Results of preference testing of synthetic speech show that the proposed cost functions generate speech of higher quality than the conventional method.

This paper describes techniques of scoring prosodic proficiency of English sentences spoken by Japanese. The multiple regression model predicts the prosodic proficiency using new prosodic measures based on the characteristics of Japanese novice learners of English. Prosodic measures are calculated by comparing prosodic parameters, such as F0, power and duration, of learner's and native speaker's speech. The new measures include the approximation error of the fitting line and the comparison result of prosodic parameters for a limited segment of the word boundary rather than the whole utterance. This paper reveals that the introduction of the new measures improved the correlation by 0.1 between the teachers' and automatic scores.

New diode structures without the field-oxide boundary across the p/n junction for ESD protection are proposed. A NMOS (PMOS) is especially inserted into the diode structure to form the NMOS-bounded (PMOS-bounded) diode, which is used to block the field oxide isolation across the p/n junction in the diode structure. The proposed N(P)MOS-bounded diodes can provide more efficient ESD protection to the internal circuits, as compared to the other diode structures. The N(P)MOS-bounded diodes can be used in the I/O ESD protection circuits, power-rail ESD clamp circuits, and the ESD conduction cells between the separated power lines. From the experimental results, the human-body-model ESD level of ESD protection circuit with the proposed N(P)MOS-bounded diodes is greater than 8 kV in a 0.35-µm CMOS process.

Automatic labeling of prosodic features is an important topic when constructing large speech databases for speech synthesis or analysis purposes. Perceptually-related F0 parameters are proposed with the aim of automatically classifying phrase final tones. Analyses are conducted to verify how consistently subjects are able to categorize phrase final tones, and how perceptual features are related with the categories. Three types of acoustic parameters are proposed and analyzed for representing the perceptual features related to the tone categories: one related to pitch movement within the phrase final, one related to pitch reset prior to the phrase final, and one related to the length of the phrase final. A classification tree is constructed to evaluate automatic classification of phrase final tones, resulting in 79.2% accuracy for the consistently categorized samples, using the best combination among the proposed acoustic parameters.

In this letter, we evaluate the performance of Optical Cross Connect (OXC) architectures equipped with limited-range wavelength converters. Performance will be evaluated according to both an optimum and a random output wavelength assignment strategy. Analytical and simulation results show the possibility to reduce the conversion degree of the Wavelength Converters while keeping network performance high.

In this study, a multiple U-shaped slot microstrip patch antenna for application to the 5 GHz band is designed and fabricated. To obtain sufficient bandwidth in the operating band, foam is inserted between the substrate and ground plane, the type of form is styrofoam, the coaxial probe source is used, and the position of the probe shift is adjusted from the center to the left. The measured result (5.02-5.955 GHz) of the fabricated antenna satisfies the conditions of VSWR < 2.0 in 5 GHz band (5.15-5.35 GHz, 5.47-5.725 GHz, 5.725-5.825 GHz), gain of 3.88-9.28 dBi, and broad radiation pattern.

2 GHz band electrically tunable superconducting microstrip line band-pass filter was developed. The tunable filter used a thin interdigital electrode. The dielectric distribution of SrTiO3 substrate included a calculated nonlinear effect of the electrode and ferroelectric material. As a result, the tunable microstrip line filter design with interdigital electrode enabled calculation by the finite element method and the moment method. The tunable filter with a measured unloaded Q factor of 9700 and a frequency shift of 1.25 MHz was obtained.

A high temperature superconductor (HTS) filter is designed and measured at 1.93 GHz, using microstrip half-wavelength spiral resonators. Resonant and coupling characteristics of miniaturized microstrip spiral resonators are investigated first. Then a 4-pole Chebyshev bandpass filter with a very narrow passband (4.1 MHz) is designed and realized using microstrip spiral resonators. The filter is fabricated using HTS YBCO films deposited on a LaAlO3 substrate. The measured frequency response of the filter agrees reasonably with the specifications, and shows that the filter owns excellent property of spurious resonance rejection over a wide frequency range.

The electric currents on the upper, lower and side surfaces of the patch conductor in a circular microstrip antenna are calculated by using the integral equation method and the characteristic between the electric currents on the upper and lower surfaces is compared. The integral equation is derived from the boundary condition that the tangential component of the total electric field due to the electric currents on the upper, lower and side surfaces of the patch conductor vanishes on the upper, lower and side surfaces of the patch conductor. The electric fields are derived by using Green's functions in a layered medium due to a horizontal and a vertical electric dipole on those surfaces. The result of numerical calculation shows that the electric current on the lower surface is much bigger than that on the upper surface and the input impedance of microstrip antenna depends on the electric current on the lower surface.

At frequencies currently used by mobile communications, many of the microstrip half-wavelength resonators are too large to realize miniaturized filters. For this reason, very small-sized microstrip spiral resonators and filters, using high-temperature superconductors (HTS), have been studied recently. In this paper, the resonant and coupling characteristics of microstrip G-type and S-type spiral resonators are investigated first by using an electromagnetic simulator. Then small-sized 4-pole, 8-pole, and 16-pole Chebyshev bandpass filters using S-type spirals are designed, respectively, with a midband frequency f0 = 1.93 GHz. The frequency responses of the filters satisfy well the desired specifications, and the measured frequency response of the 8-pole HTS filter agrees well with the theoretical prediction.

As a highly efficient radio link technology, the opportunistic scheduling policy has been widely investigated and implemented. Therefore, new challenges come up in the case of TCP over opportunistic scheduling systems. In this paper we investigate the impact of wireless opportunistic scheduling on TCP throughput. It shows that the optimization of the wireless link mechanisms needs to be maintained at the transport layer by cooperation of the adjacent layers. We propose a new ACK Reservoir Method to smooth the TCP behavior combating against the spurious timeout caused by scheduling. Based on performance analysis and simulation results, the proposed method is shown to enhance the TCP throughput by up to 100% in the presence of opportunistic scheduling. Finally, the proposed method is evaluated in a practical simulation scenario of CDMA/HDR system.

Novel microstrip lowpass filters are developed with reduced size and significantly improved stopband characteristics. After introducing quarter-wavelength open stubs, we get one or two transmission zeros in the stopband. By folding the high impedance microstrip lines, we reduce the size of the filter. Three-pole and five-pole lowpass filters are designed, and their measured frequency responses agree well with theoretical predictions.