A new Gray map between codes over F2+uF2+u2F2 and codes over F2 is defined. We prove that the Gray image of a linear (1-u2)-cyclic code over F2+uF2+u2F2 of length n is a binary distance invariant linear quasi-cyclic code. We also prove that, if n is odd, then every binary code which is the Gray image of a linear cyclic code over F2+uF2+u2F2 of length n is equivalent to a quasi-cyclic code.

In this letter, orthogonal frequency division multiplexing-code division multiplexing (OFDM-CDM) using a novel 2-dimensional spreading scheme is proposed as a candidate for a next-generation multiple access scheme. Full residual frequency diversity gain can be obtained with OFDM-CDM by adapting the proposed 2-dimensional spreading scheme with a novel frequency-hopping technique. Setting the frequency-hopping pattern in proper consideration of the coherent channel bandwidth allows us to exploit both the full frequency diversity and the time diversity in any channel environment.

An unsupervised adaptive signal processing method of principal components analysis (PCA) neural networks (NN) based on signal eigen-analysis is proposed to permit the eigenstructure analysis of lower signal to noise ratios (SNR) direct sequence spread spectrum (DS) signals. The objective of eigenstructure analysis is to estimate the pseudo noise (PN) of DS signals blindly. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, which duration is two periods of PN sequence. Then an autocorrelation matrix is computed and accumulated by these signal vectors one by one. Lastly, the PN sequence can be estimated by the principal eigenvector of autocorrelation matrix. Since the duration of temporal window is two periods of PN sequence, the PN sequence can be reconstructed by the first principal eigenvector only. Additionally, the eigen-analysis method becomes inefficient when the estimated PN sequence is long. We can use an unsupervised adaptive method of PCA NN to realize the PN sequence estimation from lower SNR input DS-SS signals effectively.

This paper describes an efficient PCRD (Post-Compression Rate-Distortion) scheme for rate control of JPEG2000. The proposed method determines the rate constant in consideration of the decreasing characteristic of RD-slopes and conducts rate allocation about only coding passes excluded from the previous rate allocation. As a result, it can considerably reduce the number of operations and encoding time with nearly the same PSNR performance as the conventional rate control scheme of JPEG2000.

A triple density Error Diffusion for medical monochrome LCDs is proposed to improve their gray-scale precisions. In addition, a measurement technique of image qualities based on E-MSE (Eye model-based Mean Square Error) is proposed. Several conventional techniques for medical LCDs, such as Sub-Pixel Modulation and Error Diffusion, are evaluated based on E-MSE and the validity of the proposed technique is ensured objectively.

The objective of this paper is to propose the Pulse Position Modulation (PPM) system which embeds the synchronizing signal in the information frame. In the proposed system, the frame for transmitting information is also the frame for acquiring frame timing. The data transmission rate of the proposed system is independent of the length of the synchronization signal because the proposed system does not require the synchronization frame. The data transmission rate and the synchronization performance for the proposed system are better than those of the conventional system.

In this paper, we propose an interactive instruction system named IMPRESSION, which allows performance of interactive presentations using multimedia educational materials in class. In recent years, although many practices of educational methodology with information technology and presentation tools using multimedia resources as educational materials have come into common use, instructors can only present such materials in a slide-sheet form through the use of such presentation tools in class. Therefore, instructors can neither do formative evaluations nor can they present suitable materials according to students' reactions in class. Our proposed methodology employs a scenario-based approach in a double loop instructional design process to overcome such problems. Instructors design an instructional plan as a scenario, and subsequently implement and modify the plan through formative evaluation during the class. They then conduct a summative evaluation based on planned and implemented instructions for redesign. To realize our methodology, in this paper we propose and design an instruction system that provides functions to select and present multimedia materials interactively provided on the Internet during the class; we then record these instructions. After implementing it, we confirmed that we can conduct the class flexibly based on our methodology through its practical use in an actual classroom environment.

This letter presents two high-performance level-converting flip-flops (LCFF) for multi-VDD systems, indirect precharging flip-flop (IPFF) and multi-supply complementary pass-transistor flip-flop (MCPFF). Employing a simple precharging scheme, IPFF provides high operating speed. MCPFF, on the other hand, provides low power operations by implementing the edge-triggering function with complementary pass transistors. Performance comparison indicates that IPFF operates at the highest speed and MCPFF consumes the lowest power among the seven LCFFs under evaluation.

A simple method for the gain improvement of matrix distributed amplifiers is presented. The method is based on modifying the central transmission line of the matrix amplifier without any changes in the input and output transmission lines. In the new method the termination impedances in the central transmission line are modified and the transmission line is replaced by an impedance matching circuitry. It has been shown that the new method can significantly improve the gain while preserving the input and output return losses of the amplifier.

In this paper, the confinement loss of octagonal photonic crystal fibers (PCFs) with an isosceles triangle lattice of air-holes are numerically investigated. Taking into account the confinement loss, the mode field diameter (MFD), the effective area (Aeff) and the chromatic dispersion of octagonal PCFs are calculated, compared to conventional hexagonal PCFs. It is found from confinement loss and MFD results that the octagonal PCFs can confine the field strongly than the hexagonal PCFs due to the different air filling fraction. Moreover, it is shown that the octagonal PCFs are obtained not only positive but also negative larger dispersion values and smaller Aeff values compared to the hexagonal PCFs.

A 32-bit embedded RISC microcontroller core targeted for automotive, industrial, and PC-peripheral applications has been developed to offer the smaller code size, lower-latency instruction and interrupt processing needed for next-generation microcontrollers. The 360 MIPS/400MFLOPS/200 MHz core--based on the Harvard bus architecture--uses 0.13/0.15-µm CMOS technology and consists of a CPU, FPU, and register banks. To reduce the size of the control programs, new instructions have been added to the instruction set. These new instructions, as well as an enhanced C compiler, produce object files about 25% smaller than those for a previous designed core. A dual-issue superscalar structure consisting of three- or five-stage pipelines provides instruction processing with low latency. The cycle performance is thus an average of 1.8 times faster than the previous designed core. The superscalar structure is used to save 19 CPU registers in parallel when executing interrupt processing. That is, it saves the 19 CPU registers to the resister bank by accessing four registers at a time. This structure significantly improves interrupt response time from 37 cycles to 6 cycles.

In this paper, we propose the construction of a web-based Question Answering (QA) system for restricted domain, which combines three resource information databases for the retrieval mechanism, including a Question&Answer database, a special domain documents database and the web resource retrieved by Google search engine. We describe a new retrieval technique of integrating a probabilistic technique based on OkapiBM25 and a semantic analysis which based on the ontology of HowNet knowledge base and a special domain HowNet created for the restricted domain. Furthermore, we provide a method of question expansion by computing word semantic similarity. The system is first developed for a middle-size domain of sightseeing information. The experiments proved the efficiency of our method for restricted domain and it is feasible to transfer to other domains expediently using the proposed method.

This paper presents a new statistical model-based voice activity detection (VAD) algorithm in the wavelet domain to improve the performance in non-stationary environments. Due to the efficient time-frequency localization and the multi-resolution characteristics of the wavelet representations, the wavelet transforms are quite suitable for processing non-stationary signals such as speech. To utilize the fact that the wavelet packet is very efficient approximation of discrete Fourier transform and has built-in de-noising capability, we first apply wavelet packet decomposition to effectively localize the energy in frequency space, use spectral subtraction, and employ matched filtering to enhance the SNR. Since the conventional wavelet-based spectral subtraction eliminates the low-power speech signal in onset and offset regions and generates musical noise, we derive an improved multi-band spectral subtraction. On the other hand, noticing that fixed threshold cannot follow fluctuations of time varying noise power and the inability to adapt to a time-varying environment severely limits the VAD performance, we propose a statistical model-based VAD algorithm in wavelet domain with an adaptive threshold. We perform extensive computer simulations and compare with the conventional algorithms to demonstrate performance improvement of the proposed algorithm under various noise environments.

Feedback-type Adaptive Array Antenna has been proposed for frequency division duplexed (FDD) system, where the mobile station (MS) measures channel characteristics and sends those back to the base station (BS). Using a higher number of feed-back bits provides better performance. However it wastes channel capacity of the up-link. On the other hand, error in feedback signals transmission causes significant performance degradation. To solve these problems, this paper proposes a method that the MS sends back the difference between the optimum weights calculated at the MS and weights which are currently used at the BS. Bit error rate performance of the system is shown under a realistic propagation condition.

An all-digital clock deskew buffer with variable duty cycles is presented. The proposed circuit aligns the input and output clocks with two cycles. A pulsewidth detector using the sequential time-to-digital conversion is employed to detect the duty cycle. The output clock with adjustable duty cycles can be generated. The proposed circuit has been fabricated in a 0.35 µm CMOS technology. The measured duty cycle of the output clock can be adjusted from 30% to 70% in steps of 10%. The operation frequency range is from 400 MHz to 600 MHz.

The hand posture estimation system by searching a similar image from a vast database, such as our previous research, may cause the increase of processing time, and prevent realtime controlling of a robot. In this study, the authors proposed a new estimation method of human hand posture by rearranging a large-scale database with the Self-Organizing Map including self-reproduction and self-annihilation, which enables two-step searches of similar image with short period of processing time, within small errors, and without deviation of search time. The experimental results showed that our system exhibited good performance with high accuracy within processing time above 50 fps for each image input with a 2.8 GHz CPU PC.

A reduced-sample-rate (RSR) sigma-delta-pipeline (SDP) analog-to-digital converter architecture suitable for high-resolution and high-speed applications with low oversampling ratios (OSR) is presented. The proposed architecture employs a class of high-order noise transfer function (NTF) with a novel pole-zero locations. A design methodology is developed to reach the optimum NTF. The optimum NTF determines the location of the non-zero poles improving the stability of the loop and implementing the reduced-sample-rate structure, simultaneously. Unity gain signal transfer function to mitigate the analog circuit imperfections, simplified analog implementation with reduced number of operational transconductance amplifiers (OTAs), and novel, aggressive yet stable NTF with high out of band gain to achieve larger peak signal-to-noise ratio (SNR) are the main features of the proposed NTF and ADC architecture. To verify the usefulness of the proposed architecture, NTF, and design methodology, two different cases are investigated. Simulation results show that with a 4th-order modulator, designed making use of the proposed approach, the maximum SNDR of 115 dB and 124.1 dB can be achieved with only OSR of 8, and 16 respectively.

This paper proposes an adaptive transmission scheme for MIMO systems to provide different bit error rates and transmission rates for multimedia traffic. The adaptive transmission scheme allocates antennas, rate and power jointly according to the feedback information to satisfy the diverse QoS requirements of the multimedia traffic. Furthermore, an efficient search algorithm with low complexity is proposed for practical implementation. Simulation results show that the proposed scheme improves the spectral efficiency while guaranteeing the QoS requirements of multimedia traffic. Moreover, the proposed search algorithm achieves close optimal performance with great complexity reduction.

A great deal of research has been made to model the vagueness and uncertainty in information retrieval. One such research is fuzzy ranking models, which have been showing their superior performance in handling the uncertainty involved in the retrieval process. However, these conventional fuzzy ranking models have a limited ability to incorporate the user preference when calculating the rank of documents. To address this issue, in this study we develop a new fuzzy ranking model based on the user preference. Through the experiments on the TREC-2 collection of Wall Street Journal documents, we show that the proposed method outperforms the conventional fuzzy ranking models.

In this study, we achieved predictable control of a wheelchair by changing the existing mapping method of the joystick, which considers the consecutive operations of a motor of a wheelchair, to a new mapping method that corresponds to the internal model of a human being. Since the existing method uses the polar coordinate system, it is not easy at all to use this method to predict either the direction of motion or the operating order for changing the position of the wheelchair according to the requirements of an operator. In order to improve the embodiment, we divided the existing joystick mapping method into two degrees of freedom-one in the vertical axis that can control the velocity and the other, in the horizontal axis for direction control. Based on this division, we implemented a wheelchair model that can be controlled by the electromyography (EMG) signal from the neck and the arm muscles of an operator. This was achieved by mapping the divided degrees of freedom onto the degrees of freedom of the neck and arm of the operator. In this case, since the operator controls the direction of motion by the joint of his/her neck, he/she can move the wheelchair in the desired direction; thus, a more intuitive human interface is implemented.