Theoretical analysis of M-ary/SS communication systems using racingcounters and a Hadamard matrix

The performance of M-ary spread spectrum (M-ary/SS) communication systems is discussed. Firstly, the initial acquisition time is evaluated. Secondly, the retention time, which is the average number of frames holding correct frame timing, and the recovery time, which is the average number of frames required to establish synchronization, are derived. Lastly, the bit-error rate (BER) performance is evaluated. M-ary/SS communication systems, which have more than one spreading code, can improve the BER performance under conditions in which there is additive white Gaussian noise (AWGN). However, the synchronization of M-ary/SS communication systems is difficult because they have several spreading codes. The frame synchronization method uses a Hadamard matrix and “racing counters.” As a result, the retention time becomes longer than the recovery time when the size of the lower counter differs greatly from that of the upper counter in the racing counters. Then the BER gets close to the performance which is achieved under complete synchronization     

Multiagent analysis for effect of cogeneration spread in an electricity market

In this paper, in order to investigate the effect of scenarios in which cogeneration spreads in an electricity market we constructed a multi‐agent model of an electricity trading market with power distribution and power generation agents. In this model, we analyzed the effect of reducing power generation surplus facilities on market price formation and stability through computer experiments. As a result of the experimental simulations, the market price was decreased by the increase of sell bids according to the demand reduction by the spread of cogeneration, and by the increase of commercial use of cogeneration facilities, the market price was more economical and stable because such agents supplied more electricity generated by surplus cogeneration. However, if power generation agents reduced the number of power generating facilities when the number of power distribution agents' cogeneration facilities was not significant, the fluctuation of market price grew larger. We confirmed that the spread of cogeneration played an important role in stabilizing market price formation. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 61–74, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20353     

Estimation of the disaster building domain using RapidEye data to estimate the amount of disaster waste

To draw reconstruction plans following major earthquakes, such as the Great East Japan Earthquake of 2011, it is necessary to quickly estimate the amount of disaster waste. To this end, remote sensing data is used, which affects all subsequent processing. However, the digital number of each pixel of the remote sensing data represents the average land cover conditions. That is, the information provided by a pixel should be represented as a one‐pixel mixed class (‘mixel’) instead of a one‐pixel single class. In previous papers, we had proposed a method of land cover classification using Thailand Earth Observation System data of a stricken area. The land cover classification results were in good agreement with a manually classified map which referenced the geological map and aerial photograph. However, to detect collapsed buildings, a minimum 2‐m ground resolution is required. Therefore, we additionally proposed a method of land cover classification using RapidEye data. The ground resolution of RapidEye data was improved to 2‐m from 6.5‐m by the proposed method. These examination results suggested that the method is effective in the classification of land cover conditions using RapidEye data. Nevertheless, the disaster building domain was not yet estimated. In this paper, we therefore propose a method to estimate the disaster building domain using RapidEye data acquired before and after an earthquake. The effectiveness of this method is confirmed by evaluation results. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A 4 Mb NAND EEPROM with tight programmed Vtdistribution

Described is a 5-V-only 4-Mb (512K×8 b) NAND EEPROM (electrically erasable programmable ROM) with tight programmed threshold voltage (V_t) distribution, controlled by a novel program-verify technique. A tight programmed V_t distribution width of 0.8 V for the 4 Mb cell array is achieved. By introducing a compact row-decoder circuit, a die size of 7.28 mm×15.31 mm is achieved using 1.0 μm design rules. A unique twin p-well structure has made it possible to realize low-power 5 V-only erase/program operation easily and to achieve 100 K-cycle endurance     

Band Structure Calculations of the High-Temperature Electronic Structure of Magnesium Oxide

The effects of high temperature on the electronic structure of a material consist of two major contributions, thermal lattice expansion and the electron-phonon interaction. These can produce dramatic changes in the electronic structure and play a critical role in the high-temperature properties and behavior of ceramics. We have used ab initio pseudofunction band structure methods to calculate the temperature dependence of the electronic structure of MgO from 300 to 1300 K modeling the independent effects of thermal lattice expansion and the electron-phonon interaction. The band structure calculations were performed self-consistently on a (MgO)₄ supercell using experimental values obtained from high-temperature X-ray diffraction to determine the lattice constants up to 1300 K and the root mean square amplitude of phonon displacements. Lattice thermal expansion contributed -0.15 meV/K to the band gap temperature dependence. Individual phonon modes, with displacements in the 〈111〉, 〈110〉, and 〈100〉 directions, were modeled using distorted lattice calculations. The electron-phonon coupling was found to be strongest for the 〈100〉 mode modeled, with strong coupling seen for modes which lead to the smallest decrease in the Mg-O bond length. The overall magnitude of the electron-phonon contribution to the band gap temperature dependence for the phonon modes modeled was −0.95 meV/K. The theoretical results account for a band gap temperature dependence in MgO of −1.1 meV/K, which compares well with the temperature dependence of approximately −1 meV/K determined experimentally using vacuum ultraviolet spectroscopy.     

Word-line architecture for highly reliable 64-Mb DRAM

A unique word-line voltage control method for the 64-Mb DRAM and beyond is proposed. It realizes a constant lifetime for a thin gate oxide. This method controls word-line voltage and compensates reliability degradation in the thin gate oxide for cell-transfer transistors. It keeps the time-dependent dielectric breakdown (TDDB) lifetime constant under any conditions of gate oxide thickness fluctuation, temperature variation, and supply voltage variation. This method was successfully implemented in a 64-Mb DRAM to realize high reliability. This chip achieved a 10⁵ times reliability improvement and a 0.3~1.8-V larger word-line voltage margin to write ONE data into the cell     

SODEL FET: novel channel and source/drain profile engineering schemes by selective Si epitaxial growth technology

In this paper, novel channel and source/drain profile engineering schemes are proposed for sub-50-nm bulk CMOS applications. This device, referred to as the silicon-on-depletion layer FET (SODEL FET), has the depletion layer beneath the channel region, which works as an insulator like a buried oxide in a silicon-on-insulator MOSFET. Thanks to this channel structure, junction capacitance (C/sub j/) has been reduced in SODEL FET, i.e., C/sub j/ (area) was /spl sim/0.73 fF//spl mu/m/sup 2/ both in SODEL nFET and pFET at Vbias =0.0 V. The body effect coefficient /spl gamma/ is also reduced to less than 0.02 V/sup 1/2/. Nevertheless, current drives of 886 /spl mu/A//spl mu/m (I/sub off/=15 nA//spl mu/m) in nFET and -320 /spl mu/A//spl mu/m (I/sub off/=10 nA//spl mu/m) in pFET have been achieved in 70-nm gate length SODEL CMOS with |V/sub dd/|=1.2 V. New circuit design schemes are also proposed for high-performance and low-power CMOS applications using the combination of SODEL FETs and bulk FETs on the same chip for 90-nm-node generation and beyond.     

Performance Analysis of Total Power Consumption in Linear Multi-hop Networks

A multi-hop network transmits the data packets through some relay nodes. In the case of equidistant transmission, it can achieve lower transmission power than a single-hop network. On the other hand, the relay nodes also have their own power consumption that does not contribute to transmission. Therefore, the total power consumption, which are the transmission power of the relay nodes and their own power consumption, can be more than that of the direct communications in the case of numbers of relay nodes and values of power consumption. In this paper, we derive theoretical expression of total power consumption with ARQ (auto repeat request) for packetized transmitted data for linear topology multi-hop networks under path loss and shadowing environments. Moreover, we consider the maximum hops which is better than direct communications in total power consumptions and the optimum hops which minimizes them and evaluate their performance using numerical calculation.     

Improved Aging Characteristics of NTC Thermistor Thin Films Fabricated by a Hybrid Sol–Gel–MOD Process

Negative temperature coefficient thermistor oxide thin films with improved aging characteristics are described. Better thermal stability has been achieved by incorporating sol–gel techniques with metallo-organic decomposition methods. A compositional range was identified whereby borosilicate may incorporate into the thermistor oxides, forming nanocomposites showing thermistor electrical characteristics. Thermistor thin films, with composition Ni_0.48Co_0.24Cu_0.6Mn_1.68O₄·0.22SiO₂·0.15B₂O₃ were deposited onto glass substrates from a solution containing organic transition metal salts, tetraethyl orthosilicate and triethyl borate. Electrical resistance measurements verified characteristic thermistor behavior. Nanocomposite thin films exhibited a factor of four improvement as compared with pure oxides after aging at 150°C for 500 h.