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Stochastic Geometry Analysis of Normalized SNR-Based Scheduling in Downlink Cellular Networks
Ohto, Takuya,Yamamoto, Koji,Kim, Seong-Lyun,Nishio, Takayuki,Morikura, Masahiro IEEE 2017 IEEE wireless communications letters Vol.6 No.4
<P>The coverage probability and average data rate of normalized SNR-based scheduling in a downlink cellular network are derived by modeling the locations of the base stations and users as two independent Poison point processes. The scheduler selects the user with the largest instantaneous SNR normalized by the short-term average SNR. In normalized SNR scheduling, the coverage probability when the desired signal experiences Rayleigh fading is shown to be given by a series of Laplace transforms of the probability density function of interference. Also, a closed-form expression for the coverage probability is approximately achieved. The results confirm that normalized SNR scheduling increases the coverage probability due to the multi-user diversity gain.</P>
Encoderless Motor Design for Servo Drive Applications
S. Murakami,M. Ohto,M. Hisatsune,T. Shiota,K. Ide 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Improvement of output power of encoderless motor is desired in servo drive applications. However, as load on the encoderless motor increases, high frequency inductance distribution distorts so heavily that rotor position estimation becomes very difficult, which is a major technical problem hindering the improvement. This paper deals with a motor design aiming for high output power encoderless motor with concentrated winding and IPM configuration. First, reduction of armature reaction is referred to as the fundamental design concept. Next, a motor configuration realizing the concept is proposed. Then, motor design is conducted, and characteristics of a prototype motor is measured and evaluated. As a result, the prototype motor is verified to achieve basic servo motor performances and to have an almost sinusoidal high frequency inductance distribution feature without crucial distortion even when load increases. Output power of encoderless motor is enhanced by the design method presented in this paper.
Park, Sang Kyu,Kim, Jin Hong,Ohto, Tatsuhiko,Yamada, Ryo,Jones, Andrew O. F.,Whang, Dong Ryeol,Cho, Illhun,Oh, Sangyoon,Hong, Seung Hwa,Kwon, Ji Eon,Kim, Jong H.,Olivier, Yoann,Fischer, Roland,Resel, Wiley - VCH Verlag GmbH & Co. KGaA 2017 Advanced Materials Vol.29 No.36
<P>A new 2:1 donor (D):acceptor (A) mixed-stacked charge-transfer (CT) cocrystal comprising isometrically structured dicyanodistyrylbenzene-based D and A molecules is designed and synthesized. Uniform 2D-type morphology is manifested by the exquisite interplay of intermolecular interactions. In addition to its appealing structural features, unique optoelectronic properties are unveiled. Exceptionally high photoluminescence quantum yield (Phi(F) approximate to 60%) is realized by non-negligible oscillator strength of the S-1 transition, and rigidified 2D-type structure. Moreover, this luminescent 2D-type CT crystal exhibits balanced ambipolar transport (mu(h) and mu(e) of approximate to 10(-4) cm(2) V-1 s(-1)). As a consequence of such unique optoelectronic characteristics, the first CT electroluminescence is demonstrated in a single active-layered organic light-emitting transistor (OLET) device. The external quantum efficiency of this OLET is as high as 1.5% to suggest a promising potential of luminescent mixed-stacked CT cocrystals in OLET applications.</P>
Grosshauser, Michael,Comba, Peter,Kim, Jee Young,Ohto, Keisuke,Thué,ry, Pierre,Lee, Young Hoon,Kim, Yang,Harrowfield, Jack The Royal Society of Chemistry 2014 Dalton Transactions Vol.43 No.15
<P>A bispidine-like ligand involving four pyridine-N and three aliphatic-N donor atoms forms a bimetallic species with CuCl<SUB>2</SUB> in which all seven N-donors are bound and which aggregates in the crystal through double chloride-bridging to give a tetranuclear unit. The magnetism of this solid can be interpreted in terms of a relatively weak antiferromagnetic coupling between the two Cu(<SMALL>II</SMALL>) centres of the dinuclear subunits and a strong ferromagnetic coupling of the Cu(<SMALL>II</SMALL>) centres in different dinuclear units involved in the bis-chlorido bridge. In solution, the assembly decays into the dinuclear subunits and, in agreement with the solid state studies, the interaction between the corresponding Cu<SUP>II</SUP> centres is shown to be primarily due to dipole–dipole coupling.</P> <P>Graphic Abstract</P><P>A binuclear complex of copper(<SMALL>II</SMALL>) chloride with a heptadentate bispidine-like ligand undergoes dimerisation in the solid state involving chloride bridging and leading to both ferro- and antiferromagnetic coupling of the Cu(<SMALL>II</SMALL>) centres. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4dt00305e'> </P>
Design of IPMSM with Eccentric Rotor and Search Coils for Absolute Position Sensorless Drive
Yong-Cheol Kwon,Seung-Ki Sul,Noor Aamir Baloch,Shinya Morimoto,Motomichi Ohto 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper, a design methodology of IPMSM for absolute position sensorless drive is proposed. In conventional researches on the absolute position estimation, initial motion of the rotor was required, which was not allowed in many applications. To eliminate the initial motion, an IPMSM with eccentric rotor with search coils is devised. In the proposed design, the information of the absolute position is included in the voltage signals at the search coils. By measuring the search coil voltages and analyzing them, the absolute position can be estimated without the initial motion of the rotor. The overall performances of the proposed motor design are evaluated by rigorous finite element analyses and experimental tests.
Adsorption Characteristics of Pb(II) and Cr(III) onto C-Methylcalix[4]resorcinarene
Jumina, Jumina,Sarjono, Ratnaningsih Eko,Siswanta, Dwi,Santosa, Sri Juari,Ohto, Keisuke Korean Chemical Society 2011 대한화학회지 Vol.55 No.3
C-Metylcalix[4]resorcinarene(CMCR)에서 Pb(II)와 Cr(III)의 흡착 특징에 대한 연구는 수행되어왔다. CMCR은 resorcinol, acetaldehyde 그리고 HCl로 부터 1단계 합성으로 만들어졌다. 일괄처리시스템에서 대부분의 변수는 CMCR이 Pb(II)와 Cr(III)에 대해 좋은 흡착제라는 것을 확인했다. Cr(III)은 Pb(II)보다 더 크게 흡착되지만 Cr(III)의 흡착속도는 Pb(II) 보다 더 느리다. Pb(II)와 Cr(III) 흡착의 흡착운동에너지는 batch안에서 유사 2차 운동 모델을 따른다. 그러나 고정상 컬럼 시스템에서 Pb(II)의 운동에너지는 일차 모델을 따른다. 흡착된 Pb(II)을 되찾기 위한 탈착 연구는 증류수와 HCl을 가지고 순차적으로 수행되었다. 그리고 그 결과는 흡착은 화학흡착에 의해 지배된다는 것을 보여주었다. A study on the adsorption characteristics of Pb(II) and Cr(III) cations onto C-methylcalix[4]resorcinarene (CMCR) has been conducted. CMCR was produced by one step synthesis from resorcinol, acetaldehyde, and HCl. Most parameters in batch system confirm that CMCR is a good adsorbent for Pb(II) and Cr(III). Cr(III) uptake was bigger than that of Pb(II), but Cr(III) adsorption rate was slower than Pb(II). The adsorption kinetic of Pb(II) and Cr(III) adsorptions in batch followed pseudo $2^{nd}$ order kinetics model, but the kinetic of Pb(II) adsorption in fixed bed column system followed first order model. Desorption studies to recover the adsorbed Pb(II) was performed sequentially with distilled water and HCl, and the results showed that the adsorption was dominated by chemisorption.
Jumina,Ifa Amalina,Sugeng Triono,Yehezkiel Steven Kurniawan,Yoga Priastomo,Keisuke Ohto,Bohari M. Yamin 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.3
At present, biodiesel remains an untapped fuel source while crude oil reserves are being depleted. Extensive efforts are necessary to achieve efficient biodiesel production, but catalytic activity in methyl palmitate production remains unsatisfactory. In this study, we report the synthesis and organocatalyst activity of C-arylcalix[4]-2-methylresorcinarene sulfonic acids for biodiesel production. The presence of a methyl group on an aromatic ring is expected to disturb the intramolecular hydrogen bonds; thus, each hydroxyl group could be utilized for the catalytic process. C-arylcalix[4]-2-methylresorcinarene sulfonic acids were prepared from cyclocondensation and sulfonation reactions yielding compounds 1?6 at rates of 66.7%?86.6%. By evaluating the organocatalytic activity of the C-arylcalix[4]-2-methylresorcinarene sulfonic acids, we found that 4?mol% of compound 5 exhibited the highest yield (97.8%) of methyl palmitate at 338?K for 6-h reaction time, which is remarkable. These findings show that C-arylcalix[4]-2-methylresorcinarene sulfonic acids are promising heterogeneous catalyst materials for biodiesel production.
Encoderless Servo Drive with Adequately Designed IPMSM for Saliency-based Position Detection
K. Ide,M. Hisatsune,T. Shiota,S. Murakami,M. Ohto 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents a newly developed encoderless servo drive with an adequately designed interior permanent magnet synchronous motor (IPMSM). The motor for encoderless servo drive is designed to act like resolver incorporated with saliency-based position detection technique. The resolution of the position detection and sustainability against load are considered in the design. As the position detection a pulse voltage injection technique is employed to realize higher dynamics in the control performance than conventional technique. This paper mainly focuses on the technology fusion in between motor design and control design. Finally, the fast initial pole positioning, the high-dynamics performance in position and speed control, which are sufficient for servo drive applications, are shown in this paper. The net-resolution of the position detection is about 10 bits, and the accuracy of positioning is less than 1 mechanical degree in position control at steady state.