Numerical approach for retention characteristics of double floating-gate memories

We report on a numerical investigation in which memory characteristics of double floating-gate (DFG) structure were compared to those of the conventional single floating-gate structure, including an interference effect between two cells. We found that the advantage of the DFG structure is its longer retention time and the disadvantage is its smaller threshold voltage shift. We also provide an analytical form of charging energy including the interference effect.Comment: 4 pages, 4 figure

フィルタ設計における計算効率改善に関する研究

Signal processing technology was first developed as analog techniques, and digital techniques were later developed in 1960-70s. Recently digital techniques often take part in analog techniques due to the accurate performance of digital signals. Figure 1.1 shows a model of analog signal processing and of digital signal processing. ...Thesis (Ph. D. in Engineering)--University of Tsukuba, (A), no. 2128, 1999.3.2

Investigation of Two Types of Vocabulary Learning: Guessing Word Meaning from Context and Consulting the Dictionary

This study explored a possible use of a self-made concordance for vocabulary learning. As a classroom activity, the students constructed their own concordances by reading a short story that included words unknown to them. The students looked up a half of the unknown words in the dictionary, while they excerpted all the sentences or phrases from the story that contained the other half of the unknown words so that they could infer the meaning of them without consulting the dictionary. A week later, the students’ retention of the meaning of unknown words was tested. The test scores were statistically compared between the group of words that the students looked up in the dictionary and the group of words that they inferred based on the lists of sentences and phrases they excerpted. The results of comparison indicated that vocabulary learning using a self-made concordance worked more effectively than using the dictionary, particularly on the students with a higher test score

Synthesis of n-type semiconducting polymer consisting of benzodipyrrolidone and thieno-[3,4-c]-pyrrole-4,6-dione via CH direct arylation

Direct arylation polycondensation of 3,​7-​bis(4-​bromophenyl)​-​1,​5-​bis(2-​octyldodecyl)​benzo[1,​2-​​b:4,​5-​b\u27]​dipyrrole-​2,​6(1H,​5H)​-​dione with 5-(2-ethylhexyl)-thieno-[3,4-c]-pyrrole-4,6-dione gave the corresponding benzodipyrrolidone-based conjugated polymer with a molecular weight of 147,000 in 92% yield. The optical and thermal properties of the polymer were evaluated. The polymer showed n-type semiconducting behavior in organic field-effect transistors with an electron mobility of 1.3 ± 0.2 × 10−3 cm2 V−1 s−1

スプライン関数とそのディジタル信号処理・画像処理への 応用に関する研究

本稿では, 2つの異なる関数基底を用いて信号を補間する手法として一般化区分的線形補間法を提案し, こうした関数系の信号処理・画像処理における有用性を検証した結果について報告する。 提案する関数系は, 線形近似と同様に近似オーダー(approximation order)が2であり, 階段関数や折れ線を正 確に再構成できる。関数基底は2つの実パラメータ τ と α によって特徴付けられる。パラメータ τ は関数基底の座標に対応するシフトパラメータであり, もう一方のパラメータaは関数の非対称性をあらわすパラメータである。これらのパラメータを変化させることで, 入力信号・画像に関係なく, 近似精度を向上させ最適化を図ることが可能となることを示す。 この補間手法では, 2つのパラメータを, τ=0.21, α=1 と設定することで, シフト線形補間 (shifted-linear interpolation) を再現することができる。ここでは, このパラメータの組み合わせ以外に, τ=0.21, α=0.58 と設定した場合に, シフト線形補間と同様の精度で信号の補間を行うことができることに注⽬する。シフト線形補間では分解プロセスにおいて IIR フィルタを必要としていたが, 後者のパラメータを設定した場合は FIR フィルタのみで構成可能である。これにより, 後者のパラメータはシフト線形補間におけるギブス (発振) 現象を大いに低減できる。 こうしたパラメータを設定した場合の有効性を, 補間操作を用いてディジタル画像を回転した場合のピーク SN 比 (原画像と回転した画像の信号・ノイズ比), 補間後の画像の最大振幅などを検証することを通して評価する

Neutrino Properties Studied with a Triton Source Using Large TPC Detectors

The purpose of the present paper is to study the neutrino properties as they may appear in the low energy neutrinos emitted in triton decay, with maximum neutrino energy of 18.6 KeV. The technical challenges to this end can be summarized as building a very large TPC capable of detecting low energy recoils, down to a few 100 eV, within the required low background constraints. More specifically We propose the development of a spherical gaseous TPC of about 10-m in radius and a 200 Mcurie triton source in the center of curvature. One can list a number of exciting studies, concerning fundamental physics issues, that could be made using a large volume TPC and low energy antineutrinos:1) The oscillation length involving the small mixing angle in the electronic neutrino disappearancei experiment is comparable to the length of the detector. Measuring the counting rate of neutrino-electron elastic scattering will give a precise measurement of the oscillation parameters free of systematic errors. First estimations show that a sensitivity of a few percent for the measurement of the above angle. 2) The low energy detection threshold offers a unique sensitivity for the neutrino magnetic moment which is about two orders of magnitude beyond the current experimental limit. 3) Scattering at such low neutrino energies has never been studied and any departure from the expected behavior may be an indication of new physics beyond the standard model. We present results of theoretical calculation and studies of possible measurements.Comment: 30 LaTex pages and 9 figure

First test of a cryogenic scintillation module with a CaWO4 scintillator and a low-temperature photomultiplier down to 6 K

Future cryogenic experiments searching for rare events require reliable, efficient and robust techniques for the detection of photons at temperatures well below that to which low-temperature photomultipliers (PMT) were characterised. Motivated by this we investigated the feasibility of a low-temperature PMT for the detection of scintillation from crystalline scintillators at T = 6 K. The scintillation module was composed of a CaWO4 scintillator and a low-temperature PMT D745B from ET Enterprises. The PMT responsivity was studied at T=290, 77 and 6 K using gamma-quanta from 241Am (60 keV) and 57Co (122 and 136 keV) sources. We have shown that the low-temperature PMT retains its single photon counting ability even at cryogenic temperatures. At T = 6 K, the response of the PMT decreases to 51 +- 13 % and 27 +- 6 % when assessed in photon counting and pulse height mode, respectively. Due to the light yield increase of the CaWO4 scintillating crystal the overall responsivity of the scintillation modules CaWO4+PMT is 94 +- 15 % (photon counting) and 48 +- 8 % (pulse height) when cooling to T = 6 K. The dark count rate was found to be 20 s-1. The energy resolution of the module remains similar to that measured at room temperature using either detection mode. It is concluded that commercially available low-temperature PMT are well suited for detection of scintillation light at cryogenic temperatures

Observation of Spin-Dependent Charge Symmetry Breaking in ΛN\Lambda N Interaction: Gamma-Ray Spectroscopy of Λ4^4_{\Lambda }He

The energy spacing between the ground-state spin doublet of $^4_\Lambda$He(1$^+$,0$^+$) was determined to be $1406 \pm 2 \pm 2$ keV, by measuring $\gamma$ rays for the $1^+ \to 0^+$ transition with a high efficiency germanium detector array in coincidence with the $^4$He$(K^-,\pi^-)$ $^4_\Lambda$He reaction at J-PARC. In comparison to the corresponding energy spacing in the mirror hypernucleus $^4_\Lambda$H, the present result clearly indicates the existence of charge symmetry breaking (CSB) in $\Lambda N$ interaction. It is also found that the CSB effect is large in the $0^+$ ground state but is by one order of magnitude smaller in the $1^+$ excited state, demonstrating that the $\Lambda N$ CSB interaction has spin dependence