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[Keyword] fluctuation(64hit)

41-60hit(64hit)

  • Validation of Rain/No-Rain Discrimination in the Standard TRMM Data Products 1B21 and 1C21

    Yuji OHSAKI  

     
    LETTER-Sensing

      Vol:
    E84-B No:8
      Page(s):
    2321-2325

    The Tropical Rainfall Measuring Mission (TRMM) is a United States-Japan joint project to measure rainfall from space. The first spaceborne rain radar is aboard the TRMM satellite. Rain/no-rain discrimination for the TRMM provides useful information for on-line data processing, storage, and post-processing analysis. In this paper, rain/no-rain discrimination for the TRMM has been validated through simulation and theory for the no-rain condition and by comparison with the ground-based radar data for rain conditions.

  • Fluctuation Analysis of Information-Transfer Systems with Feedback Confirmation Channels by Means of Fuzzy-Set-Valued Mapping Concept

    Kazuo HORIUCHI  Yasunori ENDO  

     
    PAPER-Nonlinear Problems

      Vol:
    E84-A No:4
      Page(s):
    1042-1049

    In any ill-conditioned information-transfer system, as in long-distance communication, we often must construct feedback confirmation channels, in order to confirm that informations received at destinations are correct. Unfortunately, for such systems, undesirable uncertain fluctuations may be induced not only into forward communication channels but also into feedback confirmation channels, and it is such difficult that transmitters always confirm correct communications. In this paper, two fuzzy-set-valued mappings are introduced into both the forward communication channel and the feedback confirmation channel, separately, and overall system-behaviors are discussed from the standpoint of functional analysis, by means of fixed point theorem for a system of generalized equations on fuzzy-set-valued mappings. As a result, a good mathematical condition is successfully obtained, for such information-transfer systems, and fine-textured estimations of solutions are obtained, at arbitrary levels of values of membership functions.

  • IP Traffic Condition Based Dynamic Optical Path Allocation Network System

    Yoshihiro NAKAHIRA  Saeko OSHIBA  

     
    LETTER

      Vol:
    E83-B No:10
      Page(s):
    2364-2367

    This paper describes experimental results of the IP traffic condition based dynamic optical path allocation network system. In the system, optical paths are dynamically allocated between congested node pairs to cope with traffic fluctuations. It seems that this experiment is the first of its kind in the world.

  • Micro Recording Performance Fluctuation and Magnetic Roughness Analysis: Methodology and Application

    Bo LIU  Wei ZHANG  Sheng-Bin HU  

     
    PAPER

      Vol:
    E83-C No:9
      Page(s):
    1530-1538

    As technology moves at an annual area density increase rate of 80-120% and channel density moves beyond 3, micro-fluctuation of media recording performance and the homogeneity of media's recording capability become serious reliability concerns in future high density magnetic recording systems. Two concepts are proposed in this work for the characterization of the micro-recording performance fluctuation at high bit and channel densities: recording performance roughness analysis and dynamic magnetic roughness analysis. The recording performance roughness analysis is based on an in-situ measurement technique of the non-linear transition shift (NLTS). Relationship between the performance roughness and the roughness of dynamic magnetic parameters are studied. Results of experimental investigations indicate that the NLTS based performance roughness analysis can reveal more details on media's recording capability and the capability fluctuation--the macro and micro fluctuation of recording performance. The dynamic magnetic roughness analysis is read/write operation based and can be used to characterize the macro and micro fluctuation of media's dynamic magnetic properties. The parameters used for the analysis include media's dynamic coercivity and the dynamic coercive squareness. Here, "dynamic" refers to the dynamic performance measured at MHz frequency. The authors also noticed in their technology development process that further methodology development and confirmation are necessary for media's dynamic performance analysis. Therefore, the work also extends to the accuracy analysis of the playback amplitude based methods for the analysis of the dynamic coercive squareness and dynamic hysteresis loop. A method which is of smaller testing error is identified and reported in this work.

  • Increasing Importance of Electronic Thermal Noise in Sub-0.1 µm Si-MOSFETs

    Nobuyuki SANO  

     
    INVITED PAPER-Device Modeling and Simulation

      Vol:
    E83-C No:8
      Page(s):
    1203-1211

    We investigate the intrinsic current fluctuations in small Si-MOSFETs via the Monte Carlo device simulation. It is demonstrated that the temporal fluctuation of the drain current in Si-MOSFETs attains a significant fraction of the averaged drain current when the device width is scaled down to the deep sub-µm regime. This is caused by the drastic decrease in the number of channel electrons. This finding holds true whenever the device width is reduced to deep sub-µm, regardless of the channel length. Most importantly, current fluctuation is associated with the quasi-equilibrium thermal noise in the heavily-doped source and drain regions, whereas its magnitude with respect to the averaged drain current is directly related to the number of channel electrons underneath the gate.

  • Reduction Method of Voltage Fluctuation of DC Power Supply in Digital IC

    Tadaharu AKINO  Yasuhiro ONO  Shinichi SHINOHARA  Risaburo SATO  

     
    LETTER

      Vol:
    E83-B No:3
      Page(s):
    622-625

    This paper describes how voltage fluctuation in the DC power supply of a digital IC can be reduced, by means of molding the package-pin in a ferrite-resin composite. The voltage fluctuation of the DC power supply, when the input terminal was driven by a 40 MHz, 5 Vp-p pulse wave, was measured using an oscilloscope. Simultaneously, the voltage spectrum of the fluctuation was measured using a spectrum analyzer. As a result, the voltage fluctuation was decreased by about 50 % when the IC package-pins were molded in a ferrite-resin composite, in which the µiac of the ferrite powder equalled 100, and the powder content was 80 weight-%. In the same IC, there was the reduction effect of the voltage spectrum of the fluctuation was recognized in the frequency range 40 MHz to 1 GHz.

  • Fluctuation Theory of Interactive Communication Channels, by means of Set-Valued Mapping Concept

    Kazuo HORIUCHI  

     
    PAPER

      Vol:
    E82-A No:9
      Page(s):
    1818-1824

    In multi-media systems, the type of interactive communication channels is found almost everywhere and plays an important role, as well as the type of unilateral communication channels. In this report, we shall construct a fluctuation theory based on the concept of set-valued mappings, suitable for evaluation, control and operation of interactive communication channels in multi-media systems, complicated and diversified on large scales. Fundamental conditions for availability of such channels are clarified in a form of fixed point theorem for system of set-valued mappings.

  • Fluctuations of Character Centroid Intervals in Laterally Written Japanese Sentences

    Tsunemasa SAIKI  Youichi KITAGAWA  Akihiro HAYASHI  

     
    PAPER-Human Communications and Ergonomics

      Vol:
    E82-A No:3
      Page(s):
    520-526

    Fluctuation characteristics of character centroid intervals in laterally written Japanese sentences are investigated by means of their spatial frequency characteristics. Power spectra of character centroid intervals in their longitudinal and transverse directions are obtained for handwritten and word processor printed sample sentences. It is shown that for fluctuation characteristics in the longitudinal direction, power spectra are inversely proportional to their spatial frequencies for handwritten sentences and proportional to them for word processor printed sentences, and there exists a remarkable difference between handwritten and word processor printed sentences. It is also shown that for fluctuation characteristics in the transverse direction, power spectra are proportional to their spatial frequencies for both handwritten and word processor printed sentences, and there is no remarkable difference between handwritten and word processor printed sentences.

  • Layout Dependent Matching Analysis of CMOS Circuits

    Kenichi OKADA  Hidetoshi ONODERA  Keikichi TAMARU  

     
    PAPER

      Vol:
    E82-A No:2
      Page(s):
    348-355

    Layout has strong influence on matching properties of a circuit. Current matching models, which characterize both local random non-uniformities and global systematic non-uniformities stochastically, are not adequate for the matching analysis taking the effect of layout realization into account. In order to consider topological information of layout into matching analysis, we propose a matching model which treats the random and systematic components separately. Also, we characterize the micro-loading effect, which modulates fabricated line-width according to the local density of layout patterns, into matching analysis. With these two techniques, we can perform matching analysis of CMOS circuits taking layout information into account.

  • Device-Deviation Tolerant Elastic-Vt CMOS Circuits with Fine-Grain Power Control Capability

    Masayuki MIZUNO  Hitoshi ABIKO  Koichiro FURUTA  Isami SAKAI  Masakazu YAMASHINA  

     
    PAPER

      Vol:
    E81-C No:9
      Page(s):
    1463-1472

    An elastic-Vt CMOS circuit is proposed which facilitates both high speed and low power consumption at low supply voltages. This circuit permits fine-grain power control on each multiple circuit block composing a chip, and it is not sensitive to design factors as device-parameter deviations or operating-environment variations. It also does not require any such additional fabrication technology as triple-well structure or multi-threshold voltage. The effectiveness of the circuits design was confirmed in applying it to specially fabricated 16-bit adders and 4-kb SRAMs based on 1. 5-V, 0. 35- µm CMOS technology.

  • Fractal Modeling of Fluctuations in the Steady Part of Sustained Vowels for High Quality Speech Synthesis

    Naofumi AOKI  Tohru IFUKUBE  

     
    PAPER-Chaos, Bifurcation and Fractal

      Vol:
    E81-A No:9
      Page(s):
    1803-1810

    The naturalness of normal sustained vowels is considered to be attributable to the fluctuations observed in the steady part where speech signal is seemingly almost periodic. There always exist two kinds of involuntary fluctuations in the steady part of sustained vowels, even if the sustained vowels are phonated as steadily as possible. One is pitch period fluctuation and the other is waveform fluctuation. In this study, frequency analyses on these fluctuations were conducted in order to investigate their general characteristics. The results of the analyses suggested that the frequency characteristics of the fluctuations were possible to be approximated as 1/fβ-like, which is regarded as the specific feature of random fractal. Therefore, a procedure based on random fractal generation methods was proposed in order to produce these fluctuations for the improvement of the voice quality of synthesized sustained vowels. A series of psychoacoustic experiments was also conducted to evaluate the proposed technique. Experimental results indicated that the proposed technique was effective for synthesized sustained vowels to be perceived as human-like. Unlike the sustained vowels which were synthesized without pitch period fluctuation nor waveform fluctuation, the synthesized sustained vowels which contained the fluctuations were not perceived as buzzer-like, which is the major problem of the voice quality of synthesized sustained vowels. However, it was also found that both of the fluctuations were not always the acoustic cues for the naturalness of normal sustained vowels. The synthesized sustained vowels which contained the fluctuations whose frequency characteristics were the same as that of white noise were perceived as noise-like, which is not at all the voice quality of normal sustained vowels. The results of psychoacoustic experiments indicated that the frequency characteristics of the fluctuations, which are possible to be modeled as 1/fβ-like, were the significant factors for the naturalness of normal sustained vowels.

  • A Plausible Mechanism for Electromagnetic Interference in the Arc Transition

    Zhuan-Ke CHEN  Toshiro HAYAKAWA  Koichiro SAWA  

     
    LETTER

      Vol:
    E81-C No:3
      Page(s):
    435-438

    The electromagnetic interference (EMI) induced by steady arc has been demonstrated to be dependent on arc voltage fluctuation when the arc transfers from the metallic phase to the gaseous phase. In order to give the physical understanding of this arc voltage fluctuation and EMI, several typical materials, such as Ag, Cu and Zr, were tested and their arc behavior was determined and compared. The experimental results indicated that the arc behavior, in particular the arc voltage fluctuation in the moment that metallic phase transfers to the gaseous phase was different for different materials. Based on the test results and former investigations, a plausible mechanism is proposed for understanding these phenomena.

  • Environmental Temperature Effect on Magnetization Stability in Particulate Recording Media

    Toshiyuki SUZUKI  Tomohiro MITSUGI  

     
    PAPER

      Vol:
    E80-C No:9
      Page(s):
    1168-1173

    This paper reports the thermal stability of particulate media, which include Co-Fe oxide, CrO2, and thick and thin MP tapes. By measuring the time decay of magnetization at room temperature, fluctuation fields were obtained as a function of reverse applied field. It was clarified that the fluctuation field has a constant and minimum value when the reverse applied field is equal to coercivity. Minimum fluctuation fields for the four particulate tapes were measured at several environmental temperatures ranging from -75 to +100. It was also clarified that the fluctuation field normalized by remanence coercivity increases as the environmental temperature increases for all tapes, indicating that it is a good measure of thermal stability. Activation volumes were also deduced as a function of temperature.

  • Model for Thermal Noise in Semiconductor Bipolar Transistors at Low-Current Operation as Multidimensional Diffusion Stochastic Process

    Yevgeny V.MAMONTOV  Magnus WILLANDER  

     
    PAPER-Electronic Circuits

      Vol:
    E80-C No:7
      Page(s):
    1025-1042

    This work presents a further development of the approach to modelling thermal (i.e. carrier-velocity-fluctuation) noise in semiconductor devices proposed in papers by the present authors. The basic idea of the approach is to apply classical theory of Ito's stochastic differential equations (SDEs) and stochastic diffusion processes to describe noise in devices and circuits. This innovative combination enables to form consistent mathematical basis of the noise research and involve a great variety of results and methods of the well-known mathematical theory in device/circuit design. The above combination also makes our approach completely different, on the one hand, from standard engineering formulae which are not associated with any consistent mathematical modelling and, on the other hand, from the treatments in theoretical physics which are not aimed at device/circuit models and design. (Both these directions are discussed in more detail in Sect. 1). The present work considers the bipolar transistor compact model derived in Ref. [2] according to theory of Ito's SDEs and stochastic diffusion processes (including celebrated Kolmogorov's equations). It is shown that the compact model is transformed into the Ito SDE system. An iterative method to determine noisy currents as entries of the stationary stochastic process corresponding to the above Ito system is proposed.

  • Si Single-Electron Transistors on SIMOX Substrates

    Yasuo TAKAHASHI  Akira FUJIWARA  Masao NAGASE  Hideo NAMATSU  Kenji KURIHARA  Kazumi IWADATE  Katsumi MURASE  

     
    INVITED PAPER

      Vol:
    E79-C No:11
      Page(s):
    1503-1508

    A Si single electron transistor (SET) was fabricated by converting a one-dimensional Si wire on a SIMOX substrate into a small Si island with a tunneling barrier at each end by means of pattern-dependent oxidation. Since the size of the Si island was as small as around 10 nm owing to this novel technique, the total capacitance of the SET was reduced to a value on the order of 1 aF, which guarantees the conductance oscillation of the SET even at room temperature. Furthermore, a linear relation between the designed wire length and the gate capacitance of SETs was obtained, which clearly indicates that the single island was actually formed in the middle of the one dimensional Si wire. These results were achieved owing to the highly reproducible fabrication process based on pattern dependent oxidation of SIMOX-Si layers. In addition, the fluctuation of the electrical characteristics of the SETs Was studied in relation to the wire size fluctuations. It was found that the fluctuatian is caused predominantly by the roughness of the sidewall surface of the resist pattern.

  • RCS Fluctuation Reduction in High-Resolution Radar

    Toshiharu ITOH  Hachiro SUEDA  

     
    PAPER-Measurement and Metrology

      Vol:
    E79-B No:7
      Page(s):
    974-977

    RCS fluctuation of targets such as ships can be reduced by the high-resolution radar. The high-resolution radar resolves the total radar echo into several parts which do not interfere each other. The reduction of interference gives stable target RCS. A simple model of the RCS fluctuation reduction is presented. Typical data for ships taken by an experimental radar which has range resolution about 0.75 m, are also shown. The analysis results show that the RCS fluctuation reduction agree with the simple model well.

  • Thermal Noise in Silicon Bipolar Transistors and Circuits for Low-Current Operation--Part : Compact Device Model--

    Yevgeny V. MAMONTOV  Magnus WILLANDER  

     
    PAPER-Integrated Electronics

      Vol:
    E78-C No:12
      Page(s):
    1761-1772

    This work deals with thermal-noise modeling for silicon vertical bipolar junction transistors (BJTs) and relevant integrated circuits (ICs) operating at low currents. The two-junction BJT compact model is consistently derived from the thermal-noise generalization of the Shockley semiconductor equations developed in work which treats thermal noise as the noise associated with carrier velocity fluctuations. This model describes BJT with the Itô non-linear stochastic-differential-equation (SDE) system and is suitable for large-signal large-fluctuation analysis. It is shown that thermal noise in silicon p-n-junction diode contributes to "microplasma" noise. The above model opens way for a consistent-modeling-based design/optimization of bipolar device noise performance with the help of theory of Itô's SDEs.

  • Fully Self-Timing Data-Bus Architecture for 64-Mb DRAMs

    Tadaaki YAMAUCHI  Koji TANAKA  Kiyohiro FURUTANI  Yoshikazu MOROOKA  Hiroshi MIYAMOTO  Hideyuki OZAKI  

     
    PAPER-Integrated Electronics

      Vol:
    E78-C No:7
      Page(s):
    858-865

    This paper proposes a fully self-timing data-bus (FSD) architecture which includes a dual data-bus driven by the read-out data itself and a complementary output differential (COD) amplifier. The proposed COD amplifier achieves a high voltage gain and a high speed data transfer with low power consumption. The read-out data is transmitted from the COD amplifier to the output terminal without the timing control caused by the fluctuation of the device parameters. Therefore the proposed FSD architecture eliminates the timing delay and achieves a timing-free data transfer even in DRAMs with a small signal level at the sense amplifier and the data line. Applying this architecture to a 64-Mb DRAM, a fast column address access time of 16 ns and a RAS access time of 32 ns have been achieved.

  • A Fluctuation Theory of Systems by Fuzzy Mapping Concept and Its Applications

    Kazuo HORIUCHI  Yasunori ENDO  

     
    PAPER-Fuzzy System--Theory and Applications--

      Vol:
    E77-A No:11
      Page(s):
    1728-1735

    This paper proposes a methodology for fine evaluation of the uncertain behaviors of systems affected by any fluctuation of internal structures and internal parameters, by the use of a new concept on the fuzzy mapping. For a uniformly convex real Banach space X and Y, a fuzzy mapping G is introduced as the operator by which we can define a bounded closed compact fuzzy set G(x,y) for any (x,y)∈X×Y. An original system is represented by a completely continuous operator f defined on X, for instance, in a form xλ(f(x)) by a continuous operator λ: YX. The nondeterministic fluctuations induced into the original system are represented by a generalized form of the fuzzy mapping equation xGβ (x,f(x)) {ζX|µG(x,f(x))(ζ)β}, in order to give a fine evaluation of the solutions with respect to an arbitrarily–specified β–level. By establishing a useful fixed point theorem, the existence and evaluation problems of the "β–level-likely" solutions are discussed for this fuzzy mapping equaion. The theory developed here for the fluctuation problems is applied to the fine estimation of not only the uncertain behaviors of system–fluctuations but also the validity of system–models and -simulations with uncertain properties.

  • Low Frequency Noise in Superconducting Nanoconstriction Devices

    Michal HATLE  Kazuaki KOJIMA  Katsuyoshi HAMASAKI  

     
    PAPER-LTS

      Vol:
    E77-C No:8
      Page(s):
    1169-1175

    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.

41-60hit(64hit)