For system identification problems, such as noise and echo cancellation, FIR adaptive filters are mainly used for their simple adaptation and numerical stability. When the unknown system is a high-Q resonant system, having a very long impulse response, IIR adaptive filters are more efficient for reduction in the order of a transfer function. One way to realize the IIR adaptive filter is a separate form, in which the numerator and the denominator are separately realized and adjusted. In the actual applications, the order of the unknown system is not known. In this case, it is very important to estimate the total order and the order assignment on the numerator and the denominator. In this paper, effects of the order estimation error on the residual error are investigated. In this form, indirect error evaluation called "equation error" is used. Through theoretical and numerical investigation, the following results are obtained. First, under estimation of the order of the denominator causes large degradation. Second, over estimation can improve the performance. However, this improvement is saturated to some extent due to cancellation of the redundant poles and zeros. Third, the system identification error is proportional to the equation error as the adaptive filter approaching the optimum. Finally, there is possibility of recovering from the unstable state as the order assignment approaches to the optimum in an adaptive process using the equation error. Computer solutions are provided to aid in gaining insight of the order assignment and stability problem.

This paper describes an image synthesis method based on an estimation of camera parameters. In order to acquire high quality images using image synthesis, we take some constraints into account, which include angle of view, synchronization of change of scale and change of viewing direction. The proposed method is based on an investigation that any camera operation containing a change of scale and a pure 3D rotation can be represented by a 2D geometric transformation. The transformation can explain all the synthesis procedure consisting of locating, synchronizing, and operating images. The procedure is described based on a virtual camera which is constituted of a virtual viewing point and a virtual image plain. The method can be efficiently implemented in such a way that each image to be synthesized undergoes the transformation only one time. The parameters in the image transformation are estimated from image sequence. The estimation scheme consists of first establishing correspondence and then estimating the parameters by fitting the correspondence data to the transformation model. We present experimental results and show the validity of the proposed method.

This paper presents an approach for assembly plan generation from an assembly illustration. Previously, we have already proposed an approach for the assembly plan related information acquisition from an assembly illustration, in which auxiliary lines were taken as clues. However, some ambiguity remains in dynamic information such as assembly operations and their execution order. We have verified through experiments that the ambiguity could be made clear by referring to the feedback information from the completed assemblage after the assembly operations shown in the current illustration. But in fact, in an assembly illustration there are not only the figures of mechanical parts and the auxiliary lines for visualizing their assembly relations, but explanatory words and explanatory lines as well. Explanatory words can basically be classified into two categories: instructions on assembly operations and mechanical part names. The former explicitly describes dynamic information such as the details of assembly operations. The latter also implies dynamic information such as the function of a mechanical part. Explanatory lines are usually drawn for making clear the explanatory relations. Naturally we consider that to integrate the information from explanatory words with that already obtained through the extraction of auxiliary lines will probably enable us to generate an unambiguous assembly plan from the currently observing illustration.

This paper proposes a new subband adaptive filtering algorithm for adaptive FIR filters. The number of taps for each subband filter is adaptively controlled based on a sum of the absolute coefficients or the coefficient power in conjunction with the subband signal power. Keeping the total number of taps constant, redundant taps are redistributed to subbands where the number of taps is insufficient. Simulation results with a white signal show that the number of taps in each subband approaches an optimum as each subband filter converges. For a colored signal, tap assignment by the new algorithm is as stable as for a white signal.

This paper proposes RSA-type cryptosystems over elliptic curves En(O, b) and En(a, O),where En(a, b): y2 x3+ax+b (mod n),and n is a product of from-free primes p and q. Although RSA cryptosystem is not secure against a low exponent attack, RSA-type cryptosystems over elliptic curves seems secure against a low multiplier attack. There are the KMOV cryptosystem and the Demytko cryptosystem that were previously proposed as RSA-type cryptosystems over elliptic curves. The KMOV cryptosystem uses form-restricted primes as p q 2(mod 3)or p q 3(mod 4), and encrypts/decrypts a 2log n-bit message over varied elliptic curves by operating values of x and y coordinates. The Demytko cryptosystem, which is an extension of the KMOV cryptosystem, uses form-free primes, and encrypts/decrypts a log n-bit message over fixed elliptic curves by operating only a value of x coordinates. Our cryptosystems, which are other extensions fo the KMOV cryptosystem, encrypt/decrypt a 2log n-bit message over varied elliptic curves by operating values of x and y coordinates. The Demytko cryptosystem and our cryptosystems have higher security than the KMOV cryptosystem because from-free primes hide two-bit information about prime factors. The encryption/decryption speed in one of our cryptosystems is about 1.25 times faster than that in the Demytko cryptosystem.

Broadcasting with secrecy of messages is important in a situation such as pay television. In pay television only a broadcasting station broadcasts a message. On the other hand, broadcast communication is also important. Broadcast communication means any user in a whole group can broadcast a message to any subset of the group. In this paper the efficiency of secure broadcast communication is discussed in terms of the length of messages sent and the encryption speed. We prove that the length of the broadcast messages is not kept less than O(n), where n is the number of receivers, when a broadcast system has a form of a single system which is defined as the generalized form of an individual key method and a master key method. In contrast, the proposed secure broadcast communication method, a multi-dimension method, keeps the length of messages sent O(mmn), where m is the number of the dimension used in the multi-dimension method. At the same time the encryption speed was reduced from O(n(log(n+C2)+C3)) of the master key method to O(mn(logmn+C1)) of the multi-dimension method.

The byte error locating codes specify the byte location in which errors are occurred without indicating the precise location of erroneous bit positions. This type of codes is considered to be useful for fault isolation and reconfiguration in the fault-tolerant computer systems. In this paper, difference between the code function of error-location and that of error-correction/error-detection is clarified. With using the concepts of unidirectional byte distance, unordered byte number and ordered byte number, the necessary and sufficient conditions of the unidirectional byte error locating codes are demonstrated.

We propose a method which can construct LOTOS specifications of communication systems from temporal properties described in Extended branching time temporal logic (EBTL) in this paper. Description of LOTOS, one of Formal Description Techniques, is based on behaviors of systems so that LOTOS permits strict expression. However, it is difficult to express temporal properties explicitly. On the other hand, Temporal logic is based on properties of systems. Thus temporal logic permits direct expression of temporal properties which can be understood intuitively. Accordingly, temporal logic is more useful than FDTs on the first step of systems specification. This method is effective in this point of view. Specifications obtained using this method can have a structured style. When temporal properties are regarded as constraints about temporal order among actions of systems, those specification can have a constraint oriented style. This method is based on sequential composition of Labelled Transition Systems (LTSs) which are semantics of LOTOS. EBTL is also defined on LTSs. In general, many LTSs satisfy the same temporal property. To obtain such the minimal LTS, the standard form of LTSs corresponding to EBTL operators are defined. Those standard LTSs are mainly tailored to the field of communication protocol. We also show conditions that original temporal properties are preserved in case of sequential composition of standard LTSs. In addition, applying this method to the Abracadabra Protocol, we show that this method can construct specifications of concrete protocols effectively.

A new BiCMOS process based on a high-speed bipolar process with 0.5 µm emitter width has been developed using a bonded SOI substrate. Double polysilicon bipolar transistors with the trench isolation, shallow junctions and the pedestal collector implantation provide a high cut-off frequency of 27 GHz. Stress induced device degradation is carefully examined and a low stress trench isolation process is proposed.

Recent achievements in low-voltage and low-power circuit techniques are reported in this paper. DC current in low-voltage CMOS circuits stemming from the subthreshold current in MOS transistors, is effectively reduced by applying switched-power-line schemes. The AC current charging the capacitance in DRAM memory arrays is reduced by a partial activation of array blocks during the active mode and by a charge recycle during the refresh mode. A very-low-power reference-voltage generator is also reported to control the internal chip voltage precisely. These techniques will open the way to using giga-scale LSIs in battery-operated portable equipment.

The throughput performance of a slotted, non-persistent Idle-Signal Casting Multiple Access (ICMA) protocol under the effects of various combinations of Rayleigh fading, lognormal shadowing, and spatial distribution of mobile users is studied. The opposing effects of propagation impairments on the performance of the protocol through simultaneously increasing the probability of receiver capture and attenuation of the received signal power level are demonstrated.

Recently there has been considerable interest in coded modulation schemes that offer multiple levels of error protection. That is, constructions of (block or convolutional) modulation codes in which signal sequences associated with some message symbols are separated by a squared Euclidean distance that is larger than the minimum squared Euclidean distance (MSED) of the code. In this paper, the trellis structure of linear unequal-error-protection (LUEP) codes is analyzed. First, it is shown that LUEP codes have trellises that can be expressed as a direct product of trellises of subcodes or clouds. This particular trellis structure is a result of the cloud structure of LUEP codes in general. A direct consequence of this property of LUEP codes is that searching for trellises with parallel structure for a block modulation code may be useful not only in analyzing its structure and in simplifying its decoding, but also in determining its UEP capabilities. A basic 3-level 8-PSK block modulation code is analyzed under this new perspective, and shown to offer two levels of error protection. To illustrate the trellis structure of an LUEP code, we analyze a trellis diagram for an extended (64,24) BCH code, which is a two-level LUEP code. Furthermore, we introduce a family of LUEP codes based on the |||-construction, using Reed-Muller (RM) codes as component codes. LUEP codes in this family have the advantage of having a well known trellis structure. Their application in constructing LUEP-QPSK modulation codes is presented, and their error performance over an AWGN channel examined.

A new recursive method for obtaining the mean waiting time in a polling system with general service order and gated service discipline is proposed. The analytical approach used to obtain the mean waiting time is via an imbedded Markov chain and a new recursive method is used to obtain the moments of pseudocycle time which are parameters in the formula for the mean waiting time. This method is computationally tractable, so the analytical results can cover a wide range of applications. Simulations are also conducted to verify the validity of the analysis.

We propose, for the first time, highly reliable flash-type EEPROM cell fabrication using in-situ multiple rapid thermal processing (RTP) technology. In this study, rapid thermal oxynitridation tunnel oxide (RTONO) film formations followed by in-situ arsenic (As)-doped floating-gate polysilicon growth by rapid thermal chemical vapor deposition (RTCVD) technologies are fully utilized. The results show that after 5104 program/erase (P/E) endurance cycles, the conventional cell shows 65% narrowing of the threshold voltage (Vt) window, whereas the RTONO cell indicates narrowing of less than 20%. A large number of nitrogen atoms (1020 atoms/cm3) are confirmed by secondary ion mass spectrometry (SIMS), pile up at the SiO2/Si interface and distribute into bulk SiO2. It is considered that in the RTONO film stable Si-N bonds are formed which minimize electron trap generation as well as the neutral defect density, resulting in lower Vt shifts in P/E stress. In addition, the RTONO film reduces the number of hydrogen atoms because of final N2O oxynitridation. The SIMS data shows that by the in-situ RTCVD process As atoms (91020 atoms/cm3) are incorporated uniformly into 1000--thick film. Moreover, the RTCVD polysilicon film indicates an extremely flat surface. The time-dependent dielectric breakdown (TDDB) characteristics of interpoly oxide-nitride-oxide (ONO) film exhibited no defect-related breakdown and 5 times longer breakdown time as compared to phosphorus-doped polysilicon film. Therefore, the flash-EEPROM cell fabricated has good charge storing capability.

Step-edge Josephson junctions (SEJJs), which are made by YBa2Cu3O7 (YBCO) thin films on MgO (100) substrates with gentle step angle (below 40 degrees) have been successfully fabricated. The step-edge, with several angles on the MgO substrate, were made using photolithography and Ar ion beam etching, and then YBCO films were deposited on the step-edges by pulsed laser deposition method. The relationships between step-angles and I-V characteristics, microwave properties and structure of SEJJs were systematically investigated. Shapiro steps were clearly observed only in step-angle range between 10 and 30 degrees. Intermittence and hysteresis on the I-V characteristics were observed above 30 mA without effect from step-angles.

This paper proposes and investigates an intelligent error-controlling scheme according to different importance of segmental information. In particular, the scheme is designed for facial images encoded by model-based coding that is a kind of intelligent compression coding. Intelligent communication systems regard the contents of information to be transmitted with extremely high compression and reliability. After highly efficient information compression by model-beaed coding, errors in the compressed information lead to severe semantic errors. The proposed scheme reduces semantic errors of information for the receiver. In this paper, we consider Action Unit (AU) as a segment of model-based coded facial image of human being and define the importance for each AU. According to the importance, an AU is encoded by an appropriated code among codes with different error-correcting capabilities. For encoding with different error controlling codes, we use three kinds of constructions to obtain unequal error protection (UEP) codes in this paper. One of them is the direct sum construction and the others are the proposed constructions which are based on joint and double coding. These UEP codes can have higher coderate than other UEP codes when minimum Hamming distance is small. By using these UEP codes, the proposed intelligent error-controlling scheme can protect information in segment in order to reduce semantic errors over a conventional error-controlling scheme in which information is uniformly protected by an error-correcting code.

Circuit techniques for realizing fast cycle time of DRAM are described. 1) A high-speed and high-efficiency word-line level Vpp supply can be obtained by a unique static CMOS double-boosted level generator (SCDB) which controls the Vpp charge supply gate. 2) A new write-control scheme eliminates the timing overhead of a read access time after write cycle in a fast page mode operation. 3) A floor plan that minimizes the load of signal paths by employing the lead-on-chip (LOC) assembly technique. These techniques are implemented in an address-multiplexed 16 Mbit CMOS DRAM using a 0.5-µm CMOS technology. A 31-ns RAS cycle time and a 19-ns fast page mode cycle time at Vcc3.3 V, and also even at Vcc1.8 V, a 53-ns RAS cycle time and a 32-ns fast page mode cycle time were achieved. This DRAM is applicable to battery-operated computing tools.

An encoder of a trellis coded modulation (TCM) is composed of a linear convolutional encoder followed by a mapper to channel signals. A new condition, under which the performance evaluation of the TCM is possible based on the 2ν state error state transition diagram, is proposed, where ν is the number of delay elements in the convolutional encoder. There have been proposed three similar methods. This paper points out the restriction of the previous methods, and proposes a new method. The condition, under which the previous method is useful, is called nuiformity, such as, the error weight profile is independent from the encoder state. When uniformity does not hold, we discuss to divide an error state into substates based on the coset decomposition of output vectors of the convolutional encoder. The coset is determined by the vector called coset selector. If the condition defined as equal dividing holds, the subdivided states can be merged and the performance can be evaluated based on the 2ν state transition diagram, even for the codes without uniformity. When the row rank of the transformation matrix, from the input vector of the encoder to the coset selector vector, is full, the equal dividing condition holds under the assumption of equally probable i.i.d. (independently identically distributed) input sequence. For TCM schemes without uniformity (in the case, previous methods can not be applied), upper bounds of the bit error rate are evaluated by the proposed method and compared with the simulation results. The difference is less than 10% in the range of bet error rate 10-4.

The magnitude of low frequency noise is studied in a Nb-(nanoconstrictions)-NbN system with adjustable current-voltage characteristics. We find that the magnitude of low frequency noise decreases sharply with increasing the subgap conductivity of the device. We suggest a qualitative explanation of this observation in terms of gradual build up of the nanoconstriction region by field assisted growth. The decrease of low frequency noise is related to the "cleanliness" of the system as measured by the amount of Andreev reflection-related conductivity. The scaling of the magnitude of low frequency noise with device resistance is also discussed.

In this paper, the Pisarenko and the Constrained Yule-Walker (CYW) estimators of a tone frequency are first newly derived from the viewpoint of using directly the autocorrelation coefficients. Then, simulation of these two estimators is carried out in some detail. The simulation results show that compared with the Pisarenko estimator the CYW estimator, which has not been adequately studied, works poorly for low and moderate Signal-to-Noise Ratio (SNR) values. However, in case of high SNR value, it yields very small bias and comparable estimation variance, and thus produces more accurate tone frequency estimates.