Wavelength conversion using the cross-gain modulation (XGM) of amplified spontaneous emission (ASE) in a traveling-wave type semiconductor optical amplifier (TW-SOA) is theoretically studied. Taking into account the spatial and temporal variations of carrier density along the SOA length, output signal and converted ASE waveforms are analyzed. We also reveal the dependency of the signal and converted ASE waveforms on input signal power and repetition frequency, and confirm that numerical analyses well agree with the experimental results. Finally we qualitatively clarify the way to improve frequency response by simulating eye-diagrams for long SOAs and assist light pumping for the first time.

This paper presents an innovative 155Mb/s burst-mode laser transmitter chip, which was designed and successfully demonstrated, and contains several new subsystems: a digitally programmed current source, programmable up to 120mA with a resolution of 0.1mA, a fast but accurate intermittent optical level monitoring circuit, and a digital Automatic Power Control (APC) algorithm. This generic and intelligent chip was developed in a standard digital 0.35µm CMOS process. Extensive testing showed a high yield and algorithm stability, as well as excellent performance. During initialization, when the transmitter is connected to the Passive Optical Network (PON) for the first time, maximum three Laser Control Fields (LCF) are needed, with a length of 17bytes (0.88microsecond at 155Mb/s), to stabilize the laser output power. In this short time, the chip can regulate the launched optical output power of any FSAN (Full Service Access Network) compliant laser diode to the required level, even in the extreme circumstances caused by outdoor operation or by battery backup operation during power outages. Other tests show that the chip can further stabilize and track this launched optical power with a tolerance lower than 1dB over a wide temperature range, during the burst mode data transmission. The APC algorithm intermittently adjusts the optical power to be transmitted in a digital way, starting from loosely specified but safe preset values, to the required stable logic "1" and "0" level. No laborious calibration of the laser characteristic curve and storage of the calibration values in lookup tables are needed, nor any off-chip adjustable component. The power consumption is significantly reduced by disabling inactive circuitry and by gating the digital high-speed clock. Although this laser transmitter was developed for FSAN PON applications, which are standardized at a speed of 155Mb/s upstream, the design concept is quite generic and can be applied for developing a wide range of burst mode laser transmitters, such as required for Gigabit PON systems or other TDMA networks.

In this paper, we propose a new computer-aided diagnosis system which can extract specific features from hematoxylin and eosin (HE)-stained breast tumor images and evaluate the type of tumor using artificial organisms. The gene of the artificial organisms is defined by three kinds of texture features, which can evaluate the specific features of the tumor region in the image. The artificial organisms move around in the image and investigate their environmental conditions during the searching process. When the target pixel is regarded as a tumor region, the organism obtains energy and produces offspring; organisms in other regions lose energy and die. The searching process is iterated until the 30th generation; as a result, tumor regions are filled with artificial organisms. Whether the detected tumor is benign or malignant is evaluated based on the combination of selected genes. The method developed was applied to 27 test cases and the distinction between benign and malignant tumors by the artificial organisms was successful in about 90% of tumor images. In this diagnosis support system, the combination of genes, which represents specific features of detected tumor region, is selected automatically for each tumor image during the searching process.

The c-Secure CRT code is a collusion-secure fingerprinting code whose code length is reduced by using the Chinese Remainder Theorem. The tracing algorithm for the c-secure CRT code drops its performance of traitor tracing when random errors are added to the codewords. In this paper, we show two approaches to enhance random-error-resilience to the tracing algorithm of the c-secure CRT code. The first approach is introducing thresholds for the distinction of the detected part of the embedded data called detected blocks. We propose a method to derive appropriate values of the thresholds on an assumption that the tracer can estimate the random error rate. This modification extends the capability of traitor tracing to the attacks in which the alteration rate of the detected blocks is not fixed to 0.5. The second approach is extending the scope of the search for the detected blocks. With numerical results by computer simulations, we confirmed an impressive improvement of random-error-resilience of a c-secure CRT code.

System-level diagnosis is a very important technique for identifying faulty processors in a system with a large number of processors. Processors can test other processors, and then output the test results. The aim of diagnosis is to determine correctly the faulty/fault-free status of all processors. The adaptive diagnosis have been studied in order to perform diagnosis more efficiently. In this paper, we present adaptive diagnosis algorithms for a system modeled by butterfly networks. Our algorithms identify all faulty nodes in butterfly networks with the optimal number of tests. Then, we design another algorithm for diagnosis with very small constant number of rounds.

We report field emission from multilayered cathodes grown on silicon and glass substrates. The cathode consist of a layer of nanoseeded diamond and overlayers of nanocluster carbon (sp2 bonded carbon) and tetrahedral amorphous carbon (predominantly sp3 bonded carbon). These films exhibit good field emission characteristics with an electron emission current density of 1µA/cm2, at a field of 5.1V/µm. The multilayered cathodes on silicon substrates exhibit even lower emission threshold field of about 1-2V/µm for an emission current density of 1µA/cm2. The emission is influenced by the nanoseeded diamond size and concentration and the properties of the nano carbon over layer.

We propose a novel pixel pattern-based approach for texture classification, which is independent of the variance of illumination. Gray scale images are first transformed into pattern maps in which edges and lines, used for characterizing texture information, are classified by pattern matching. We employ principal component analysis (PCA) which is widely applied to feature extraction. We use the basis functions learned through PCA as templates for pattern matching. Using PCA pattern maps, the feature vector is comprised of the numbers of the pixels belonging to a specific pattern. The effectiveness of the new feature is demonstrated by applications to the image retrievals of the Brodatz texture database. Comparisons with multichannel and multiresolution features indicate that the new feature is quite time saving, free of the influence of illumination, and has comparable accuracy.

We propose a new closed-loop power control scheme for wireless mobile communication systems using an adaptive step size. The proposed scheme selects the basic power control step size by considering the speed of the mobile station and a variable step size by using instantaneous companding logic based on power control command bit patterns. We show its improved performance in view of the standard deviation of received power at the base station in consideration of channel BER.

In this paper, we will show that some families of periodic sequences over Z4 and Z8 with period multiple of 2r-1 generated by r-th degree basic primitive polynomials assorted by the root of each polynomial, and give the exact distribution of sequences for each family. We also point out such an instability as an extreme increase of their linear complexities for the periodic sequences by one-symbol substitution, i.e., from the minimum value to the maximum value, for all the substitutions except one.

In this paper we present reconfigurable computing as a compelling choice of computing platform for real-time, onboard processing for satellite applications. In particular, we discuss the use of reconfigurable computing in the context of a real-time remote sensing system, providing motivation for such a system and describing attributes of reconfigurable computing that support it as the technology of choice. The High Performance Computing (HPC-I) payload, designed and developed for the Australian scientific satellite FedSat, is introduced as a demonstration of onboard processing in space using reconfigurable logic. We present an overview of the real-time remote sensing system architecture, and describe the design and implementation of three remote sensing algorithms in HPC-I for cloud masking, wildfire detection and volcanic plume detection. Finally, results from simulation and testing are presented which show very promising performance in terms of data throughput and detection capabilities.

An automatic LSI package lead inspection system for backside lead specification is proposed. The proposed system inspects not only lead backside contamination but also the mechanical lead specification such as lead pitch, lead offset and lead overhangs (variations in lead lengths). The total inspection time of a UQFP package with a lead count of 256 is less than the required time of 1 second. Our proposed method is superior to the threshold method used usually, especially for the defect between leads.

We propose a new algorithm for blind source separation (BSS), in which frequency-domain independent component analysis (FDICA) and time-domain ICA (TDICA) are combined to achieve a superior source-separation performance under reverberant conditions. Generally speaking, conventional TDICA fails to separate source signals under heavily reverberant conditions because of the low convergence in the iterative learning of the inverse of the mixing system. On the other hand, the separation performance of conventional FDICA also degrades significantly because the independence assumption of narrow-band signals collapses when the number of subbands increases. In the proposed method, the separated signals of FDICA are regarded as the input signals for TDICA, and we can remove the residual crosstalk components of FDICA by using TDICA. The experimental results obtained under the reverberant condition reveal that the separation performance of the proposed method is superior to those of TDICA- and FDICA-based BSS methods.

In this study, wave propagation phenomena of phase differences observed in van der Pol oscillators coupled by inductors as a ladder are investigated. The phenomena are called "phase waves. " We classify the observed phenomena and analyze the difference in detail. We observe that the behavior of the phase waves generated by giving a phase difference of positive value is different from the behavior of those generated by giving a phase difference of negative value. We can also observe the generation of two pairs of phase waves. We clarify the mechanisms of these complicated phenomena. Finally, for the case of nine oscillators, we carry out both computer calculations and circuit experiments. Circuit experimental results agree well with computer calculated results qualitatively.

A formula-based approach for extracting the inductance of on-chip VLSI interconnections is presented. All of the formulae have been previously proposed and are well-known, but the degrees of accuracy they provide in this context have not previously been examined. The accuracy of the equations for a 0.1 µm technology node is evaluated through comparison of their results with those of 3-D field solvers. Comprehensive evaluation has proven that the maximum relative error of self- and mutual inductances as calculated by the formulae are less than 5% for parallel wires and less than 13% for angled wires, when wire width is limited to no more than 10 times the minimum. When applied to a realistic example with 43 wire segments, a program using the formula-based approach extracts values more than 60 times faster than a 3-D field solver.

When decision-directed channel estimation is used for QAM-OFDM systems, the optimal filter shape depends on the amplitudes of the modulated symbols as well as the channel characteristics. In this letter we propose a simple channel estimation method for multi-level-amplitude-modulated systems, which can effectively suppress the estimation variances with a small filter. Using the proposed method the implementation cost can be reduced and possibly better results might be obtained by avoiding the estimation bias due to large-sized filtering.

There exists an optimum power assignment, which can be obtained by solving a set of linear equations, for multi-cell CDMA networks. According to the direct method, we have to measure all the link gains to solve these linear equations. We propose in this paper an indirect method which allows each base station to only measure the received power for each user in its cell area and the interference from each other-cell. Compared to the direct method, the number of measurements can be largely reduced.

This paper describes multigrain parallel processing on OSCAR (Optimally SCheduled Advanced multiprocessoR) chip multiprocessor architecture. OSCAR compiler cooperative chip multiprocessor architecture aims at development of scalable, high effective performance and cost effective chip multiprocessor with ease of use by compiler supports. OSCAR chip multiprocessor architecture integrates simple single issue processors having distributed shared data memory for optimal use of data locality over different loops and fine grain data transfer and synchronization, local data memory for private data recognized by compiler, and compiler controllable data transfer unit for overlapping data transfer to hide data transfer overhead. This OSCAR chip multiprocessor and OSCAR multigrain parallelizing compiler have been developed simultaneously. Performance of multigrain parallel processing on OSCAR chip multiprocessor architecture is evaluated using SPEC fp 2000/95 benchmark suite. When microSPARC like single issue core is used, OSCAR chip multiprocessor architecture gives us 2.36 times speedup in fpppp, 2.64 times in su2cor, 2.88 times in turb3d, 2.98 times in hydro2d, 3.84 times in tomcatv, 3.84 times in mgrid and 3.97 times in swim respectively for four processors against single processor.

Following the developments in the use of ID-based schemes and smart cards, Yang and Shieh proposed two password authentication schemes to achieve two purposes: (1) to allow users to choose and change their passwords freely, and (2) to make it unnecessary for the remote server to maintain a directory of passwords or a verification table to authenticate users. Recently, Chan and Cheng showed that Yang and Shieh's timestamp-based password authentication scheme is insecure against forgery. In this paper, we point out that Chan and Cheng's forgery attack can not work. Thus, we further examine the security of Yang and Shieh's password authentication schemes and find that they are insecure against forgery because one adversary can easily pretend to be a valid user and pass the server's verification which allows the adversary to login to the the remote server.

A fast-motion-estimation (ME) algorithm called a "breaking-off-search (BOS)" was developed. It can improve processing speed of the full-search (FS) method by a factor of 3.4. The BOS algorithm can not only sometimes achieve better visual quality than FS, but can also solve visual degradation problems associated with conventional fast-ME algorithms whenever picture patterns change (i. e. , presence of scene changes). The power dissipation of a 0.6-µ m CMOS parallel Wallace-tree motion estimator using BOS was reduced to about 281 mW which was 1/28.7 that of the 0.6-µ m CMOS binary-tree motion estimator using FS.

This paper describes an ultra low power, motion estimation (ME) processor for MPEG2 HDTV resolution video. It adopts a Gradient Descent Search (GDS) algorithm that drastically reduces required computational power to 6 GOPS. A SIMD datapath architecture optimized for the GDS algorithm decreases the clock frequency and operating voltage. A low power 3-port SRAM with a write-disturb-free cell array arrangement is newly designed for image data caches of the processor. The proposed ME processor contains 7-M transistors, integrated in 4.50 mm 3.35 mm area using 0.13 µm CMOS technology. Estimated power consumption is less than 100 mW at 81 MHz@1.0 V. The processor is applicable to a portable HDTV system.