Near-field scanning optical microscopic transient lens for carrier dynamics study in InGaN/GaN

Time-resolved microscopic transient lens (TR-M-TL) and near-field scanning optical microscopic transient lens (NSOM-TL) were performed to reveal temporal and spatial behavior of carrier dynamics in InGaN/GaN quantum wells. The carrier and thermal dynamics were observed through the time profile of the TR-M-TL signal. Also, NSOM-photoluminescence and NSOM-TL images were observed at the same time. By comparing these two images, both radiative and nonradiative recombination centers in InGaN active layer were unambiguously discriminated with submicrometer scale. Such nonradiative carrier dynamics has been difficult to observe by conventional techniques in spite of its importance

Surface plasmon enhanced spontaneous emission rate of InGaN/GaN quantum wells probed by time-resolved photoluminescence spectroscopy

We observed a 32-fold increase in the spontaneous emission rate of InGaN/GaN quantum well (QW) at 440 nm by employing surface plasmons (SPs) probed by time-resolved photoluminescence spectroscopy. We explore this remarkable enhancement of the emission rates and intensities resulting from the efficient energy transfer from electron-hole pair recombination in the QW to electron vibrations of SPs at the metal-coated surface of the semiconductor heterostructure. This QW-SP coupling is expected to lead to a new class of super bright and high-speed light-emitting diodes (LEDs) that offer realistic alternatives to conventional fluorescent tubes

Confocal microphotoluminescence of InGaN-based light-emitting diodes

Spatially resolved photoluminescence (PL) of InGaN/GaN/AlGaN-based quantum-well-structured light-emitting diodes (LEDs) with a yellow-green light (530 nm) and an amber light (600 nm) was measured by using confocal microscopy. Submicron-scale spatial inhomogeneities of both PL intensities and spectra were found in confocal micro-PL images. We also found clear correlations between PL intensities and peak wavelength for both LEDs. Such correlations for yellow-green and amber LEDs were different from the reported correlations for blue or green LEDs. This discrepancy should be due to different diffusion, localization, and recombination dynamics of electron-hole pairs generated in InGaN active layers, and should be a very important property for influencing the optical properties of LEDs. In order to explain the results, we proposed a possible carrier dynamics model based on the carrier localization and partial reduction of the quantum confinement Stark effect depending on an indium composition in InGaN active layers. By using this model, we also considered the origin of the reduction of the emission efficiencies with a longer emission wavelength of InGaN LEDs with high indium composition

Onoma-to-wave: Environmental sound synthesis from onomatopoeic words

In this paper, we propose a framework for environmental sound synthesis from onomatopoeic words. As one way of expressing an environmental sound, we can use an onomatopoeic word, which is a character sequence for phonetically imitating a sound. An onomatopoeic word is effective for describing diverse sound features. Therefore, using onomatopoeic words for environmental sound synthesis will enable us to generate diverse environmental sounds. To generate diverse sounds, we propose a method based on a sequence-to-sequence framework for synthesizing environmental sounds from onomatopoeic words. We also propose a method of environmental sound synthesis using onomatopoeic words and sound event labels. The use of sound event labels in addition to onomatopoeic words enables us to capture each sound event's feature depending on the input sound event label. Our subjective experiments show that our proposed methods achieve higher diversity and naturalness than conventional methods using sound event labels

Environmental sound synthesis from vocal imitations and sound event labels

One way of expressing an environmental sound is using vocal imitations, which involve the process of replicating or mimicking the rhythm and pitch of sounds by voice. We can effectively express the features of environmental sounds, such as rhythm and pitch, using vocal imitations, which cannot be expressed by conventional input information, such as sound event labels, images, or texts, in an environmental sound synthesis model. In this paper, we propose a framework for environmental sound synthesis from vocal imitations and sound event labels based on a framework of a vector quantized encoder and the Tacotron2 decoder. Using vocal imitations is expected to control the pitch and rhythm of the synthesized sound, which only sound event labels cannot control. Our objective and subjective experimental results show that vocal imitations effectively control the pitch and rhythm of synthesized sounds.Comment: Submitted to ICASSP202

Length of Corolla as an Indicator of the Most Effective Period for Prebloom GA Treatment of Muscat Bailey A and Delawere Grapes

ブドウに対するGA前処理の適期を判定するためには,花器の発達程度を知ることが重要である. そこで,マスカット・ベーリーAとデラウェアについて,処理適期における花らい各部の大きさと処理効果との関連性を調査した. 1)マスカット・ベーリーＡ10園で調査したGA処理適期における平均花冠長は,いずれも2.0～2.2mmの範囲内で,適期の2,3日前または後には1.6～1.9mm,及び2.3～2.5mmとなり,いずれも適期における値とは有意の差があった. 2)同一のベーリーA樹につき,3年連続して適期における新梢と花器の発達を調査した結果,花冠長は新梢長や展葉数にくらべて,年次による相違が少なかった. 3)デラウェアについても同様の傾向が認められ,加温園1か所を含む5園における処理適期の花冠長は1.8～2.0mmであった. 1.6mm以下または2.1mm以上の時期に処理すると,ばら房になったり,有種子果粒が混入した. 4)以上の結果及び測定が容易であることから,花冠長はGA処理適期を判定するための有効かつ実用的な指標であると考えられる

Regardation of the Secondary Growth of Lateral Shoot and Stimulation of the Development of Inflorescence Primordia by CCC Spray after the Harvest Time of Neo Muscat Grapes in a Heated Plastic Greenhouse

欧州系ブドウ,ネオ･マスカットを12月または1月からハウス内で加温促成すると,翌年は花穂を持たない新梢が多く発生することが多い. 収穫期後（7月上旬）に腋芽中の花穂原基を無加温樹の同時期（9月上旬）のものと比べると,翌年の結果枝となるはずの基部の芽の花穂原基数が少なく,その発育程度も劣っていた. 加温樹では,その後秋までの数カ月間に旺盛な2次生長をしたが,CCCを葉面散布しておくと著しく抑えられ,冬季せん定時における花穂原基数もやや増えていた. CCCを散布した主枝では. 翌春の発芽新梢数が多く,それらの花穂着生率も高かった