A novel type of optically clocked all-optical flip-flop based on a coupled-mode distributed Bragg reflector laser diode is proposed. The device operates as a bistable laser, where the two lasing modes at different wavelength are switched all-optically by injecting a clock pulse together with a set/reset signal. We employ an analytical model based on the two-mode coupled rate equations to verify the basic operation of the device numerically. Optically clocked flip-flop operation is obtained with a set/reset power of 0.60 mW and clock power of 1.8 mW. The device features simple structure, small footprint, and synchronized all-optical flip-flop operation, which should be attractive in the future digital photonic integrated circuits.

This paper presents a new non-interactive string-commitment scheme that achieves universally composable security. Security is proven under the decisional composite residuosity (DCR) assumption (or the decisional Diffie-Hellman (DDH) assumption) in the common reference string (CRS) model. The universal composability (UC) is a very strong security notion. If cryptographic protocols are proven secure in the UC framework, then they remain secure even if they are composed with arbitrary protocols and polynomially many copies of the protocols are run concurrently. Many UC commitment schemes in the CRS model have been proposed, but they are either interactive commitment or bit-commitment (not string-commitment) schemes. We note, however, that although our scheme is the first non-interactive UC string-commitment scheme, a CRS is not reusable. We use an extension of all-but-one trapdoor functions (ABO-TDFs) proposed by Peikert and Waters at STOC 2008 as an essential building block. Our main idea is to extend (original deterministic) ABO-TDFs to probabilistic ones by using the homomorphic properties of their function indices. The function indices of ABO-TDFs consist of ciphertexts of homomorphic encryption schemes (such as ElGamal, and Damgåd-Jurik encryption). Therefore we can re-randomize the output of ABO-TDFs by re-randomization of ciphertexts. This is a new application of ABO-TDFs.

An efficient method is proposed for reconstructing speakerphone-mode cellular phone sound. The overall transfer function from digital PCM signals stored in a cellular phone to dummy head-recorded signals is modeled as a combination of a cellular phone transfer function (CPTF) and a cellular phone-to-listener transfer function (CPLTF). The CPTF represents the linear and nonlinear characteristics of a cellular phone and is modeled by the Volterra model. The CPLTF represents the effect of the path from a cellular phone to a dummy head and is measured. Listening tests show the effectiveness of the proposed method. An application scenario of the proposed method is also addressed for sound quality assessment of cellular phones in speakerphone mode.

This paper proposes a method for detecting determiner errors, which are highly frequent in learner English. To augment conventional methods, the proposed method exploits a strong tendency displayed by learners in determiner usage, i.e., mistakenly omitting determiners most of the time. Its basic idea is simple and applicable to almost any conventional method. This paper also proposes combining the method with countability prediction, which results in further improvement. Experiments show that the proposed method achieves an F-measure of 0.684 and significantly outperforms conventional methods.

We present pseudo-preimage attacks on Davis-Meyer mode of reduced rounds of the block ciphers ARIA, Camellia, and Serpent by using Sasaki's framework. They yield preimage or second-preimage attacks on PGV hashing modes. We develop proper initial structures for applying meet-in-the-middle techniques to the block ciphers, by considering their diffusion layers, and propose a method to find matching-check equations for indirect partial matching technique with a binary matrix. These works enable us to attack 5 rounds of ARIA, 7 rounds of Camellia, and 4 rounds of Serpent faster than brute force attack.

A novel Template Updating system for fingerprint verification systems used in mobile applications is introduced in the paper. Based on the proposed method, the system performance is improved much more than the original one. Not only the FRR (False Reject Rate) but also the small overlap problem caused by the very narrow sensor on the mobile phone are solved. Based on the template updating system, templates are replaced with matched inputs towards a target structure which can expand the coverage of templates with large displacement and rotation. By using the test database, the system performance shows the FRR can be reduced by 79% in comparison with the one without template updating procedure. This system was adopted in practical mobile phones in the commercial market in 2009.

The probe used in the conventional SAR measurement is usually calibrated in a well filled with tissue-equivalent liquid surrounded by a rectangular waveguide and a matching dielectric window in the frequency range from 800 MHz to 3 GHz. However, below 800 MHz, the waveguides are too large to be used for the calibration. Therefore, we have developed another technique of calibrating the SAR-probe, that is, relating the output voltage of the probe to the field intensity produced by a reference antenna in the tissue-equivalent liquid by using two-antenna method. In this paper, the calibration system using the reference dipole antennas in the liquid at 450 MHz, 900 MHz and 2450 MHz is presented and far-field gain of the reference antenna and calibration factor of the SAR-probe are measured and compared with those obtained by using the conventional waveguide system.

A total-field/scattered-field (TF/SF) boundary for the constrained interpolation profile (CIP) method is proposed for multi-dimensional electromagnetic problems. Incident fields are added to or subtracted from update equations in order to satisfy advection equations into which Maxwell's equations are reduced by means of the directional splitting. Modified incident fields are introduced to take into account electromagnetic fields after advection. The developed TF/SF boundary is examined numerically, and the results show that it operates with good performance. Finally, we apply the proposed TF/SF boundary to a scattering problem, and it can be solved successfully.

We consider Downlink (DL) scheduling for a multi-user cooperative cellular system with fixed relays. The conventional scheduling trend is to avoid interference by allocating orthogonal radio resources to each user, although simultaneous allocation of users on the same resource has been proven to be superior in, e.g., the broadcast channel. Therefore, we design a scheduler where in each frame, two selected relayed users are supported simultaneously through the Superposition Coding (SC) based scheme proposed in this paper. In this scheme, the messages destined to the two users are superposed in the modulation domain into three SC layers, allowing them to benefit from their high quality relayed links, thereby increasing the sum-rate. We derive the optimal power allocation over these three layers that maximizes the sum-rate under an equal rates' constraint. By integrating this scheme into the proposed scheduler, the simulation results show that our proposed SC scheduler provides high throughput and rate outage probability performance, indicating a significant fairness improvement. This validates the approach of simultaneous allocation versus orthogonal allocation in the cooperative cellular system.

In this paper, we propose a two-step TDC with phase-interpolator and time amplifier to satisfy high resolution at 2.4 GHz input frequency by implementing delay time less than that of an inverter delay. The accuracy of phase-interpolator is improved for process variation using the resistor automatic-tuning circuit. The gain of time amplifier is improved using the delay time difference between two delay cells. It is implemented in a 0.13 µm CMOS process with a die area of 0.68 mm2. And the power consumption is 14.4 mW at a 1.2 V supply voltage. The resolution and input frequency of the TDC are 0.357 ps and 2.4 GHz, respectively.

The specific absorption rate (SAR) measurement procedure for wireless communication devices used in close proximity to the human body other than the ear was standardized by the International Electrotechnical Commission (IEC). This procedure is applicable to SAR measurement of data communication terminals that are used with host devices. Laptop PCs are assumed as host devices in this study. First, numerical modeling of laptop PCs and the validity of computations are verified with corresponding measurements. Next, mass averaged SARs are calculated dependent on the dimensions of the laptop PCs and the position of the terminals. The results show that the ratio of the maximum to minimum SARs is at most 2.0 for USB dongle and card-type terminals at 1950 MHz and 835 MHz.

In this letter, we present a novel timing offset estimation method for chirp-based communication systems which is robust against frequency offset. For robust timing offset estimation, we propose a partial cross-correlation and differential multiplication method using up and down chirp symbols. The performances of the proposed estimator in indoor multipath channel model provided by IEEE 802.15.4a standard are presented in terms of mean-square error (MSE) obtained by computer simulation. The simulation results show that the proposed estimator has a significantly smaller MSE than the conventional estimators.

A circularly-polarized planar array antenna using hexagonal aperture elements is proposed. A 22-element subarray as the basic unit is excited by a corporate-feed circuit located in the lower layer of the double-layered antenna. The hexagonal aperture is designed to achieve a good axial ratio in the boresight. A 1616-element array antenna with uniform element spacing smaller than the free-space wavelength was fabricated by diffusion bonding of laminated thin metal plates for the 60 GHz-band. The high gain of 33.4 dBic is measured with 91.6% antenna efficiency, including losses.

With the increasing demand of high video quality and large image size, adaptive interpolation filter (AIF) addresses these issues and conquers the time varying effects resulting in increased coding efficiency, comparing with recent H.264 standard. However, currently most AIF algorithms are based on either frame level or macroblock (MB) level, which are not flexible enough for different video contents in a real codec system, and most of them are facing a severe time consuming problem. This paper proposes a content based coarse to fine AIF algorithm, which can adapt to video contents by adding different filters and conditions from coarse to fine. The overall algorithm has been mainly made up by 3 schemes: frequency analysis based frame level skip interpolation, motion vector modeling based region level interpolation, and edge detection based macroblock level interpolation. According to the experiments, AIF are discovered to be more effective in the high frequency frames, therefore, the condition to skip low frequency frames for generating AIF coefficients has been set. Moreover, by utilizing the motion vector information of previous frames the region level based interpolation has been designed, and Laplacian of Gaussian based macroblock level interpolation has been proposed to drive the interpolation process from coarse to fine. Six 720p and six 1080p video sequences which cover most typical video types have been tested for evaluating the proposed algorithm. The experimental results show that the proposed algorithm reduce total encoding time about 41% for 720p and 25% for 1080p sequences averagely, comparing with Key Technology Areas (KTA) Enhanced AIF algorithm, while obtains a BDPSNR gain up to 0.004 and 3.122 BDBR reduction.

In this paper, we propose a new method to estimate and effectively reduce the effect of thermal asperity (TA) in the perpendicular magnetic recording (PMR) channels with the state trellis. The TA is estimated from the state trellis, then its average is used to modify the equalized signal entering the Viterbi detector. For the partial response (PR) targets with DC component, the proposed method with a maximum-likelihood detector can improve the bit error rate performance by more than an order of magnitude when TA occurs and degrades when the giant magneto-resistive (GMR) nonlinearity and base line wander (BLW) effects are present. Unlike the previous studies, this method allows the use of PR targets with DC component under the presence of TA.

As a global feature of fingerprint patterns, the Orientation Field (OF) plays an important role in fingerprint recognition systems. This paper proposes a fast binary pattern based orientation estimation with nearest-neighbor search, which can reduce the computational complexity greatly. We also propose a classified post processing with adaptive averaging strategy to increase the accuracy of the estimated OF. Experimental results confirm that the proposed method can satisfy the strict requirements of the embedded applications over the conventional approaches.

Ultra-wide band (UWB) pulse radar has high range resolution, and is thus applicable to imaging sensors for a household robot. To enhance the imaging region of UWB radar, especially for multiple objects with complex shapes, an imaging algorithm based on aperture synthesis for multiple scattered waves has been proposed. However, this algorithm has difficulty realizing in real-time processing because its computation time is long. To overcome this difficulty, this letter proposes a fast accurate algorithm for shadow region imaging by incorporating the Range Points Migration (RPM) algorithm. The results of the numerical simulation show that, while the proposed algorithm affects the performance of the shadow region imaging slightly, it does not cause significant accuracy degradation and significantly decreases the computation time by a factor of 100 compared to the conventional algorithm.

Since retina blood vessels (RBV) are a major factor in ophthalmological diagnosis, it is essential to detect RBV from a fundus image. In this letter, we proposed the detection method of RBV using a morphological analysis and support vector machine classification. The proposed RBV detection method consists of three strategies: pre-processing, features extraction and classification. In pre-processing, noises were reduced and RBV were enhanced by anisotropic diffusion filtering and illumination equalization. Features were extracted by using the image intensity and morphology of RBV. And a support vector machine (SVM) classification algorithm was used to detect RBV. The proposed RBV detection method was simulated and validated by using the DRIVE database. The averages of accuracy and TPR are 0.94 and 0.78, respectively. Moreover, by comparison, we confirmed that the proposed RBV detection method detected RBV better than the recent RBV detections methods.

High-performance 1.3-µm electroabsorption modulators integrated with DFB lasers are developed for long-reach 100 Gbit Ethernet. The dynamic extinction ratio of over 8-dB with the voltage swing of 2 V are achieved for the four LAN-WDM lanes (14 nm wavelength range) used in 100 Gbit Ethernet with the same modulator structure. The fabricated devices are packaged in butterfly modules and four-lane 40-km single mode fiber transmission at 25-Gbit/s operation is demonstrated. Further, a can-type transmitter optical subassembly is fabricated to reduce the cost and size of transmitter modules. The use of a low-dielectric-constant liquid crystal polymer transmission line makes the 3-dB bandwidth larger and enables 25-Gbit/s operation with CAN-TOSA module.

Silicon Mach-Zehnder interferometric (MZI) waveguide modulator incorporating the n-channel junction field-effect transistor (JFET) as a signal modulation unit was designed, fabricated, and analyzed. The proposed MZI with JFET was designed to operate based on the plasma dispersion effect in the infrared wavelength of 1550 nm. The three different modulation lengths (ML) of 500, 1000, and 2000 µm while keeping the overall MZI length constant at 1.5 cm were set as a general design rule for these 10 µm-wide MZIs under study. When the JFET was operated in an active mode by injecting approximately 50 mA current (Is) to achieve a π phase shift, the modulation efficiency of the device was measured to be η = π /(Is· L) 40π/A-mm. The temporal and frequency response measurements also demonstrate that the respectively rise and fall times measured using a high-speed photoreceiver were in the neighborhood of 8.5 and 7.5 µsec and the 3 dB roll-off frequency (f3 dB) measured was in the excess of 400 kHz.