A parametric linear filter for a linear observation model usually requires a parameter selection process so that the filter achieves a better filtering performance. Generally, criteria for the parameter selection need not only the filtered solution but also the filter itself with each candidate of the parameter. Obtaining the filter usually costs a large amount of calculations. Thus, an efficient algorithm for the parameter selection is required. In this paper, we propose a fast parameter selection algorithm for linear parametric filters that utilizes a joint diagonalization of two non-negative definite Hermitian matrices.

A stacked rectangular microstrip antenna with a shorting plate is proposed as a car antenna for dual band (VICS and ETC) operation in the ITS. The proposed antenna has the proper radiation patterns for the VICS and ETC. The antenna is small in size and effective in dual band operation.

We have built a CLQA (Cross Language Question Answering) system for a source language with limited data resources (e.g. Indonesian) using a machine learning approach. The CLQA system consists of four modules: question analyzer, keyword translator, passage retriever and answer finder. We used machine learning in two modules, the question classifier (part of the question analyzer) and the answer finder. In the question classifier, we classify the EAT (Expected Answer Type) of a question by using SVM (Support Vector Machine) method. Features for the classification module are basically the output of our shallow question parsing module. To improve the classification score, we use statistical information extracted from our Indonesian corpus. In the answer finder module, using an approach different from the common approach in which answer is located by matching the named entity of the word corpus with the EAT of question, we locate the answer by text chunking the word corpus. The features for the SVM based text chunking process consist of question features, word corpus features and similarity scores between the word corpus and the question keyword. In this way, we eliminate the named entity tagging process for the target document. As for the keyword translator module, we use an Indonesian-English dictionary to translate Indonesian keywords into English. We also use some simple patterns to transform some borrowed English words. The keywords are then combined in boolean queries in order to retrieve relevant passages using IDF scores. We first conducted an experiment using 2,837 questions (about 10% are used as the test data) obtained from 18 Indonesian college students. We next conducted a similar experiment using the NTCIR (NII Test Collection for IR Systems) 2005 CLQA task by translating the English questions into Indonesian. Compared to the Japanese-English and Chinese-English CLQA results in the NTCIR 2005, we found that our system is superior to others except for one system that uses a high data resource employing 3 dictionaries. Further, a rough comparison with two other Indonesian-English CLQA systems revealed that our system achieved higher accuracy score.

Automatic prosody labeling is the task of automatically annotating prosodic labels such as syllable stresses or break indices into speech corpora. Prosody-labeled corpora are important for speech synthesis and automatic speech understanding. However, the subtleness of physical features makes accurate labeling difficult. Since errors in the prosodic labels can lead to incorrect prosody estimation and unnatural synthetic sound, the accuracy of the labels is a key factor for text-to-speech (TTS) systems. In particular, mora accent labels relevant to pitch are very important for Japanese, since Japanese is a pitch-accent language and Japanese people have a particularly keen sense of pitch accents. However, the determination of the mora accents of Japanese is a more difficult task than English stress detection in a way. This is because the context of words changes the mora accents within the word, which is different from English stress where the stress is normally put at the lexical primary stress of a word. In this paper, we propose a method that can accurately determine the prosodic labels of Japanese using both acoustic and linguistic models. A speaker-independent linguistic model provides mora-level knowledge about the possible correct accentuations in Japanese, and contributes to reduction of the required size of the speaker-dependent speech corpus for training the other stochastic models. Our experiments show the effectiveness of the combination of models.

The recent progress in sensor and wireless communication technologies has enabled the design and implementation of new applications such as sensor telemetry which is the use of wireless sensors to gather fine-grained information from products, people and places. In this work, we consider a realistic telemetry application in which an area is periodically monitored by a sensor network which gathers data from equally spaced sample points. The objective is to maximize the lifetime of the network by jointly selecting the sensing nodes, the node transmission powers and the route to the base station from each sensing node. We develop an optimization-based algorithm OPT-RE and a low complexity algorithm SP-RE for this purpose and analyze their dynamics through extensive numerical studies. Our results indicate that SP-RE is a promising algorithm which has comparable performance to that of the more computationally intensive OPT-RE algorithm. The energy consumption is significantly affected by the channel access method, and in this paper, we also compare the effects of the collision free TDMA and contention based CSMA/CA methods. We propose practical enhancements to CSMA/CA so that the energy consumption due to collisions is reduced. Our simulation results indicate that with the proposed enhancements contention based channel access can provide comparable performance to that of the collision free methods.

In this paper, the cross-correlation distribution between a p-ary m-sequence s(t) and its p + 1 distinct decimated sequences s(dt + l) is derived. For an odd prime p, an even integer n, and d = pk +1 with gcd(n, k) = 1, there are p + 1 distinct decimated sequences s(dt + l), 0 ≤ l < p + 1, for a p-ary m-sequence s(t) of period pn -1 because gcd(d, pn - 1) = p + 1. The maximum magnitude of their cross-correlation values is 1 + p if l ≡ 0 mod p + 1 for n ≡ 0 mod 4 or l ≡ (p + 1)/2 mod p + 1 for n ≡ 2 mod 4 and otherwise, 1 + . Also by using s(t) and s(dt + l), a new family of p-ary sequences of period pn -1 is constructed, whose family size is pn and Cmax is 1 + p.

This paper describes a beam scanning antenna that consists of a movable dielectric plate loaded onto a microstrip comb-line antenna. This type of antenna uses a mechanical system and so offers a simple structure and low cost. The main beam direction of the proposed antenna is changed by moving the dielectric plate. The guide wavelength of the microstrip line was measured at the quasi-millimeter wave band (20 GHz) when moving the dielectric plate to investigate the possibility of beam scanning. The proposed antenna was fabricated to experimentally demonstrate its principle operation. A possible beam scanning angle of 20 degrees was confirmed.

In this letter, we design an optimal superimposed training scheme for orthogonal frequency division multiplexing (OFDM) systems. A linear least square (LS) channel estimator is developed, and optimal pilot symbols are proposed with respect to the channel estimate's mean square error (MSE). The optimal power allocation between training and data is derived by maximizing the averaged channel capacity lower bound. Simulation results validate our optimum design.

Near-field imaging has been intensively investigated to observe the shape and the physical properties of objects, aiming at wide applications in the areas of science and engineering. In this research, by using 60 GHz band waveguide-type microscopic aperture probe, the characteristics of the near-field imaging in transmission mode have been studied by simulation and experiment. The probe is made of a WR-15 rectangular waveguide with end-shielded metal plate and a 0.5 mm-diameter aperture. In the simulation, at first, the electric field distribution at the aperture, at the rear (waveguide) and the front positions (free space) are presented. Second, the transmitted electric fields are presented for three cases: (a) scanning of a dielectric slit, (b) by varying the distance between the aperture and a dielectric sample, and (c) scanning of a dielectric groove. In the experiment, the lateral resolution with a two-slit and the depth resolution with grooves having various depths in rectangular format are described and the results show both resolutions to be much shorter than the wavelength. Finally, the scanned images of the letter N punched through a dielectric material and a leaf are demonstrated.

Recently, a lot of UWB antennas have been reported by many research groups. Most of the reported antennas have omnidirectional radiation characteristics. The disadvantage of using omnidirectional antennas is that the antenna performance can be degraded by adjacent walls or metals. If unidirectional UWB antennas are utilized, the degradation on the antenna performance due to omnidirectionality can be avoided. Another important topic in UWB antennas is the waveform distortion caused by antennas' transmission characteristics. In impulse-based UWB communications, waveform distortions of transmitted and received pulses caused by antennas deteriorate the communication performance. Therefore, the development of UWB antennas having small waveform distortions is highly desirable. In this paper, we propose a novel bowtie antenna using leaf-shaped radiating elements and a flat reflector. This antenna has unidirectional radiation patterns over the frequency range of 3.0 to 10.5 GHz. The actual gain in the maximum radiation direction is 6.0-9.0 dBi in the frequency range of 4.5-9.4 GHz (relative bandwidth of 71%). The cross-correlations between source pulse and received pulse waveforms are 0.89-0.94, and hence the waveform distortion caused by this antenna is relatively small. As a result, the proposed antenna is useful for impulse-based UWB communication systems using correlation detection.

Transmission characteristics of a left-handed (LH) ferrite microstrip line are significantly affected by the nonuniform DC bias magnetic field in the ferrite substrate (internal magnetic field Hin) caused by the inhomogeneous demagnetizing effect because the strip conductors of these devices must be mounted at the edge of the ferrite substrate. Three dimensional analyses on the LH ferrite microstrip line are performed taking into account the nonuniform internal magnetic field Hin. The analytical results show that the nonuniform internal magnetic field under the strip conductor near the edge of the ferrite substrate is useful for spreading the frequency band of negative permeability and nonreciprocal operation, and for improvement of both the insertion and return losses of the LH ferrite microstrip line. Measured results of more than 20 dB isolation with 2.2 dB insertion loss and 1.33 GHz bandwidth are corresponding well to the analytical results.

Novel multiband circular microstrip antennas (C-MSAs) with multiple half-ring slots are presented in this paper. Two antenna-feeding systems, i.e. an embedded L-probe beneath the patch and a coplanar circular arc- shaped probe (T-probe), are used to feed the C-MSA with multiple half-ring slots. The embedded L-probe is used to excite the C-MSA with a double-layer dielectric substrate due to its tremendous performance to provide a wideband impedance matching. The coplanar T-probe is proposed to realize an excellent multiband C-MSA in a single-layer structure. The C-MSA with four half-ring slots fed by the embedded L-probe exhibits satisfactory radiation characteristics. Five frequencies with broadside radiation patterns and gains of at least 5.0 dBi are obtained. It is also confirmed by simulation that resonant frequency and gain can be easily controlled to meet the desired frequency requirements. Moreover, the C-MSA with three half-ring slots fed by the coplanar T-probe presents satisfactory performance over the four observed frequencies with good return losses (-10 dB reference). Broadside radiation patterns with acceptable cross-polarization level and gains in the range of 3.0-7.0 dBi are obtained. Couplings between the C-MSA and the coplanar T-probe have an important contribution to obtain good return losses. It can be controlled by adjusting the distance between them and the arc angle of the coplanar T-probe appropriately. Experiments of both types of antenna were conducted to verify the simulation results and good agreements are confirmed. Due to the performances, these two C-MSAs are considered to be an effective model as a multiband planar antenna.

This paper investigates the prospects and challenges of hierarchical optical path networks. The merits and issues of introducing higher order optical paths are elucidated. State of the art of the key enabling technologies are demonstrated including hierarchical optical cross-connect switch architectures, hierarchical optical path network design algorithms, a newly developed waveband filter, and waveband conversion technologies.

In this paper we propose a cross-layer retransmission control for TCP communication over a wireless link. With our proposed control, a retransmission delay for lost packet is reduced, packet losses in the wireless link are eliminated and all packets are delivered in the correct order. No change is required to TCP itself or to the sender. Our proposed method is implemented in a queue between the media access control (MAC) layer and logical link layer in a base station, and is designed to assist local retransmission control in the MAC layer. Computer simulations show that our proposed method can maximally use the bandwidth of the wireless link under high bit error rates conditions with conventional TCP control. The fairness problem of TCP communication between connections with different bit error rates in a wireless link is also improved, and MAC level fairness is also controllable.

Fe thin films were deposited directly and via Ag underlayer on glass and MgO(100) substrates by MBE. Polycrystal Fe films grew on the glass substrate while single crystal films grew on the MgO(100) substrate. Fe film growth followed the Volmer-Weber mode for both cases. The Fe film structure was influenced by the surface roughness of Ag underlayer at the early stage of film growth. The relationships between the Fe thin film morphology and the magnetic properties are discussed.

In order to realize a higher density version of the conventional optical disk, shorter wavelength laser and narrower track pitch have been put to practical use. However, using narrow track pitch can cause the increase of the crosstalk from the adjacent tracks. Moreover, the use of narrow pitch and short wavelength can also give rise to the increase of deterioration of the detected signal characteristics due to the microscopic roughness of disk surface. In this paper, in order to estimate the effect of surface roughness theoretically, we try to analyze the light-beam scattering and detected signal characteristics of a blue laser optical disk model with random rough surfaces by the Finite Difference Time Domain (FDTD) method.

In this paper, a compact ultra-wideband bandpass filter (UWB-BPF) using pseudo-interdigital stepped-impedance resonators (PIDT-SIRs) is designed and implemented on a commercial printed circuit board (PCB) of RT/Duroid 5880 substrate. The first two resonant modes of the SIR are coupled together and they are applied to create a wide passband. The proposed filter at center frequency f0 of 7.1 GHz has very good measured characteristics including the bandwidth of 3.68-10.46 GHz (3-dB fractional bandwidth of 95%), low insertion loss of -0.50.4 dB, sharp rejection due to two transmission zeros in the passband edge created by the inter-stage coupling. Experimental results of the fabricated filter show a good agreement with the predicted results.

For a microstrip antenna (MSA) with a ring-shaped slot on formed on the ground plane, downsizing the microstrip patch and expanding the circularly polarized bandwidth have been achieved successfully. The dimensions of the patch are 6.8 mm7.4 mm and the minimum axial ratio (AR) of 0.6 dB is obtained at 6.1 GHz. In addition, its AR is less than 3 dB at the relative bandwidth of 3.5%. The bandwidth of the proposed MSA is twice that of conventional single-feeding circularly polarized MSAs; however, its size is only half that of conventional MSAs.

The class of complete complementary sequences (of fixed length) have the ideal correlation properties and are good at increasing the channel usage efficiency but lacks in desirable sequence lengths. In spread spectrum communication systems, sequences having nice correlation properties are important in many ways such as in suppressing multi-user interference, for reliable initial synchronization and in separation of the multipath components. It would be even good if the sequences are easy to construct and have desirable lengths for the system under consideration. In this paper, M sets of sequences that constitute a complete complementary sequences with ith set containing N sequences of length Li each, i = 0, 1, ..., M - 1, is defined and a general method that constructs such a class of complete complementary sequences (of different lengths) is given. The proposed class of complete complementary sequences, constituted by sequence sets of different lengths, does not increase the data rates when short-length sequences are employed.

A communication means is presented for patients with amyotrophic lateral sclerosis in totally locked-in state who are completely unable to move any part of the body and have no usual communication means. The method utilizes changes in cerebral blood volume accompanied with changes in brain activity. When a patient is asked a question and the answer to it is 'yes', the patient makes his or her brain active. The change in blood volume at the frontal lobe is detected with near-infrared light. The instantaneous amplitude and phase of the change are calculated, and the maximum amplitude and phase change are obtained. The answer 'yes' or 'no' of the patient is detected using a discriminant analysis with these two quantities as variables. The rate of correct detection is 80% on average.