This paper proposes the signaling network deployment for mobile networks with a goal of reducing the signaling cost and time to set up calls. In this deployment, we solve the heavy concentration of signaling traffic resulting from the centralized database used in current mobile networks. The solution exploits the features of the distributed databases, data partition, locality of mobile users, and Common Channel Signaling System No.7 (CCSS No.7) network architectures. We assume the area served by the mobile network is partitioned into a few zones. There is a database associated with each zone. A numbering database strategy is proposed in this paper for the mobiles to register at some specific nearby databases according to their mobile identification numbers. Thus, a calling party can directly locate the called party by the mobile identification number he/she dialed. This method can reduce over 95% of the location-updating cost and 70% of the location-tracking cost under a general sumulation model. We also present the implementation considerations of this strategy. This implementation is an enhancement of the routing function of the Signaling Connection Control Part in CCSS No.7 protocol stacks. With few modifications on current mobile networks, the proposed strategy can obtain very excellent results.

The electric field intensity of the THz radiation from YBCO thin films excited by ultrashort laser pulses has been enhanced by a factor of 3 using a-axis oriented films instead of c-axis oriented ones used previously under the same excitation conditions. This corresponds to the enhancement of a factor of 10 for the radiation power. From the transmittance measurements of the millimeter wave for a-and c-axis oriented films, the origin of the enhancement is attributed to the increased fraction of the THz electromagnetic wave power transmitted from the YBCO film to free space. This result indicates that the utilization of the anisotropic properties of high-Tc superconductors is effective to enhance the radiation power.

The problem of restoring binary (black and white) images degraded by color-dependent flip-flap noises is considered. The real image is modeled by a Markov Random Field (MRF). The Iterated Conditional Modes (ICM) algorithm is adopted. It is shown that under certain conditions the ICM algorithm is insensitive to the MRF image model and noise parameters. Using this property, we propose a parameter-free restoration algorithm which does not require the estimations of the image model and noise parameters and thus can be implemented fully in parallel. The effectiveness of the proposed algorithm is shown through applying the algorithm to degraded hand-drawn and synthetic images.

While estimating glitches or spurious transitions is a challenge due to signal correlations, the random behavior of logic gate delays makes the estimation problem even more difficult. In this paper, we present statistical estimation of signal activity at the internal and output nodes of combinational and sequential CMOS logic circuits considering uncertainty of gate delays. The methodology is based on the stochastic models of logic signals and the probabilistic behavior of gate delays due to process variations, interconnect parasitics, etc. We propose a statistical technique of estimating average-case activity, which is flexible in adopting different delay models and variations and can be integrated with worst-case analysis into statistical logic design process. Experimental results show that the uncertainty of gate delays makes a great impact on activity at individual nodes (more than 100%) and total power dissipation (can be overestimated up to 65%) as well.

This paper presents a logic synthesis method for look-up table (LUT) based field programmable gate arrays (FPGAs). We determine functions to be mapped to LUTs by functional decomposition for each of single-output functions. To share LUTs among several functions, we use a new Boolean resubstitution technique. Resubstitution is used to determine whether an existing function is useful to realize another function; thus, we can share common functions among two or more functions. The Boolean resubstitution proposed in this paper is customized for an LUT network synthesis because it is based on support minimization for an incompletely specified function. Experimental results show that our synthesis method produces a small size circuit in a practical amount of time.

A design methodology of the analog currentmode bandwidth programmable integrator for a low voltage (3V) and low power application is developed and the integrator designed by this method is successfully fabricated by a 0.8µm CMOS n-well single poly/double metal process. The integrator ocuppies the active chip area of 0.3mm2. The experimental result illustrates a low power dissipation (1.0mW-3.55mW), 65dB of the dynamic range, and bandwidth programmability (10MHz-30MHz) with an external digital 4bit.

This paper presents an exact minimization algorithm for AND-OR-EXOR three-level networks, where a single two-input exclusive-OR (EXOR) gate is used. The network realizes an EXOR of two sum-of-products expressions (EX-SOP), where the two sum-of-products expressions (SOP) can share products. The objective is to minimize the total number of different products in the two SOPs. An algorithm for the exact minimization of EX-SOPs with up to five variables are shown. Up to five variables, EX-SOPs for all the representative functions of NP-equivalence classes were minimized. For five-variable functions, we confirmed that minimum EX-SOPs require up to 9 products. For n-variable functions, minimum EX-SOPs require at most 92n-5 (n6) products.

In this paper we propose a comprehensive approach to physical design based on the constraint paradigm. Bounds on the most critical circuit parasitics are automatically generated to help designers and/or physical design tools meet a set of high-level specifications. The constraint generation engine is based on constrained optimization, where various parasitic effects on interconnect and devices are accounted for and dealt with in different manners according to their statistical behavior and their effect on performance.

For the completely polarized wave case, this paper presents the explicit formulae of the characteristic polarization states in the co-polarized radar channel, from which one can obtain the CO-POL Max, the CO-POL Saddle and the CO-POL Nulls in the Stokes vector form. Then the problem on the polarimetric contrast optimization is discussed, and the explicit formula of the optimal polarization state for contrast enhancement is presented in the Stokes vector form for the first time. To verify these formulae, we give some numerical examples. The results are completely identical with other authors', which shows the validity of the presented method.

We report the strong microwave Josephson radiation from an array of high-Tc junctions on a MgO bicrystal substrate from centimeter- to millimeter-wave ranges. The dc bias current was fed to the junction array having parallel geometry with the pair of junctions shunted by superconducting loops. The configuration of bias leads was a series of interlocking dc SQUID's geometry which guaranteed the oscillation of all junctions at the same frequency. For a five-junctions array, we observed the coherent output power of about 13 pW at receiving frequency fREC22GHz without an external magnetic flux, which was nearly five times higher than that of a single bicrystal junction. We observed the Josephson linewidth of the selfradiation in coherent state less than 1 GHz by the adjustment of the external flux. The phase differences between adjacent junctions with different IcRn products could be controlled by an external small magnetic field. Submillimeter-wave detector response of the five-junction array was also studied experimentally at frequency f478 GHz.

We report on progress in the development of high-current-density all-NbN tunnel junctions for application as submillimeter wave SIS mixers. A very high current density up to 54 kA/cm2, roughly an order of magnitude larger than any reported results for all-NbN tunnel junctions, was achieved in the junctions with a thin aluminum nitride (AIN) tunnel barrier. Even though the junctions have a very high current density, they showed high-quality junction characteristics with a large gap voltage, sharp quasipartical current rise, and small subgap leakage current. The junctions also exhibited good Josephson tunneling behavior, excellent terahertz response, and sensitive heterodyne mixing properties. NbN/AIN/NbN tunnel junctions were integrated with a NbN thin-film antenna to investigate the terahertz responses and the heterodyne mixing properties in a quasioptical mixer testing system. Photon-assisted tunneling steps were clearly observed on the I-V curve with irradiation up to 1 THz, and low-noise heterodyne mixing was demonstrated in the 300-GHz band.

This study shows the results of evaluating the flux noises at low frequency when the alternating current(AC) bias direct offset integrated technique(DOIT) with additional positive feedback (APF) is used in a high-Tc dc superconducting quantum interference device (SQUID). The AC-bias DOIT can reduce low-frequency noise without increasing the level of white noise because each operating point in the two voltage-flux characteristics with AC bias can always be optimum on the magnetometer in the high-Tc dc-SQUID. APF can improve the effective flux-to-voltage transfer function so that it can reduce the equivalent flux noise due to the voltage noise of the preamplifier in the magnetometer. The use of APF combined with the AC-bias DOIT reduced the noise of the magnetometer by factors of 1.5 (33µΦ0/Hz vs. 50 µΦ0/Hz) at100 Hz, 3.5 (43 µΦ0/Hz vs. 150 µΦ0/Hz) at 10 Hz, and 5.2 (67 µΦ0/Hz vs. 351 µΦ0/Hz) at 1 Hz as compared with the noise levels that were obtained with the static-current-bias DOIT. The contribution of the factors at 1 Hz is about 2 by APF and 2.6 by AC bias. The performance of improving the flux noise in the AC -bias DOIT with APF is almost equal to that of the flux locked loop (FLL) circuits in which the flux modulation uses a coupling system with a transformer and with the AC bias.

High-Tc SQUID was applied to the detection of magnetized fine particle moving at high speed. Two types of SQUIDs were used. One was a large washer type and the other was a flux transformer type. Their Josephson junctions were step edge type. The iron particle was attached on a nylon wire and scanned under the SQUID. High-Tc SQUID detected an iron particle of 50 µm diameter running at 800 m/min. It was shown that the magnetic field measured by the SQUID was proportional to the volumer of the particle and is inversely proportional to the distance between the SQUID and the particle. This technique using high-Tc SQUID is hopeful not only to wire production line but also for the processing of food and medicine, etc.

New THz radiation devices made of high-Tc superconductors are fabricated and their characteristics are studied in detail. Ultrashort electromagnetic pulses with 0.5 ps width have been radiated into free space from current biased devices made of superconducting YBa2Cu3O7 (YBCO) films by exciting with femtosecond laser pulses. The Fourier spectrum of them extends up to 3 THz. The radiation mechanism is ascribed to the ultrafast supercurrent modulation by the optical pulses. The THz waveform is analyzed using rate equations describing the relaxation of photoexcited quasiparticles. By the improvement of the device structure and the collecting optics, the radiation power can be increased up to 0.5 µW. A new type THz radiation from YBCO films under an external magnetic field without a transport current is also reported.

A parallel IP router that uses off-the-shelf wor-kstations and interconnecting switches is presented. This router, called CORErouter-I, is a medium-grained, functionally distributed parallel system consisting of four kinds of processors for routing, routing-table searching, servicing, and line interfacing. Also discussed are issues related to the implementation of CORErouter-I, especially in terms of routing protocol processing and packet-forwarding. Performance characteristics of CORErouter-I are also clarified through several experiments performed to evaluate maximum throughput, analyze packet-forwarding time, and estimate the effect of parallel processing on the route-flapping problem.

A punctured convolutional coded PR4ML system for digital magnetic recording, which applies a punctured coding method to the convolutional code and records the punctured code sequences on two tracks, is proposed. In this study, the bit error rate performance of the proposed system is obtained by computer simulation taking account of partial erasure, which is one of the nonlinear distortions at high densities, and it is compared with those of a conventional 8/9 coded PR4ML system and an I-NRZI coded PR4ML system. The results show that the proposed system is hardly affected by partial erasure and exhibits good performance in high-density recording. A bit error rate of 10-4 can be achieved with SNR's of approximately 13.2 dB and 9.1 dB less than those of the conventional 8/9 coded and I-NRZI coded PR4ML systems, respectively, at a normalized linear density of 3.

A modified frequency domain method for analyzing nonlinear waveform distortion in a magnetic recording process is presented. The measurement technique combines a 5th harmonic measurement technique, which uses a specific 30-bit pattern including dibits, and a precompensation technique for the dibits. The 5th harmonic voltage ratio given by the former technique includes the amount of NLTS (Nonlinear transition shift) and PE (Partial erasure) in dibits. The latter precompensation technique is employed to evaluate the PE as the minimum in the 5th harmonic voltage ratio. The true NLTS can be estimated from the amount of distortion and the evaluated PE. The high accuracy of the technique was confirmed by an examination using a pulse pattern generator with varied phase and amplitude. Finally, the effects of medium properties such as coercivity and squareness on the nonlinear distortions have been investigated by applying the technique to particulate flexible media. The NLTS increased with squareness from 3.5% to 7% while PE was less than 6% for any squareness at a recording density of 76 kFRPI. When coercivity became large, NLTS and PE decreased. The direction of NLTS for Ba-ferrite media agreed with that for a perpendicular Co-Cr thin-film medium.

A series of CoxAg1-x (0x100at.%) granular films were prepared using the ion-beam cosputtering technique at different substrate temperatures. Systematic investigations have been carried out on the giant magnetoresistance (GMR) effect and characterization of microstructures of these samples. The magnetoresistance ratio depends strongly on cobalt concentration, substrate temperature, and annealing treatment. The optimal value of GMR was observed in Co22Ag78 sample prepared at the temperature of 300 K. Microstructures of as-deposited and annealed samples were characterized by structural analyses. For Co22Ag78 sample, real-time in situ observation by TEM together with FMR spectra indicates that the size and shape of cobalt granules evolve primarily along the film plane during annealing. The results of FMR also provide that the cobalt granules remain single-domain particles after annealing at temperatures up to 700 K.

Recently, many types of high-density recording technologies for future MO (Magneto-Optical) storage have been reported. MSR (Magnetically Induced Super Resolution) technology is one of the most promising candidates, and over ten types of MSR technologies have been already proposed. However, they are not well-discussed from the viewpoint of total recording technology which would include the recording and readout methods, the pick-up technology and the signal processing technology. Key technologies for realizing MO storage of over 7 GBytes in a CD-sized disk using a red laser are proposed, and the experimental results pertaining to each key technology are described. The write/read characteristics were examined for the CAD (Center Aperture Detection)-MSR disk. From the characteristics of the CAD-MSR disk combined with laser pumped magnetic field modulation recording, it was shown that land/groove (0.7 µm width) recording with the linear density of 0.27 µm/bit and track pitch below 0.7 µm can be realized. It was also shown that CAD-MSR disk is well combined with an OSR (Optical Super Resolution) pick up, laser pumped read-out and PRML (Partial Response Maximum Likelihood) technologies which are very useful to achieve a high density MO disk. Using CAD-MSR disk combined with above technologies together, high density write/read with a bit length of 0.2 µm and a track pitch of 0.6 µm should be realized with using the laser of 635 nm wavelength. Applying the CAD-MSR disks to a CD sized MO disk, the capacity becomes over 7 GBytes (Format efficiency: 80%), which is 20 times higher than 5.25 inches MO disk and 1.5 times than DVD-ROM.

In this paper, we present an error concealment method to recover damaged blocks for block-based image coding schemes. Imperfect transmission of image data results in damaged blocks in the reconstructed images. Hence recovering damaged image blocks is needed for reliable image communications. To recover damaged blocks is to estimate damaged blocks from the correctly received or undamaged neighborhood information with a priori knowledge about natural images. The recovery problem considered in our method is to estimate a larger block, which consists of a damaged block and the undamaged neighborhood, from the undamaged neighborhood. To find an accurate estimate, a set of the feature vectors is introduced and an estimate is expressed as a linear combination of the feature vectors. The proposed method recoveres damaged blocks by projecting the undamaged neighborhood information onto the feature vectors. The sequential projections onto the feature vectors algorithm is proposed to find the projection coefficients of the feature vectors to minimize the squared difference of an estimate and the undamaged neighborhood information. We tested our algorithm through computer simulations. The experimental results showed the proposed method ourperforms the frequency domain prediction method in the PSNR values by 4.0-5.0dB. Tthe reconstructed images by the proposed method provide a good subjective quality as well as an objective one.