• Title/Summary/Keyword: region based structure

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Stability of a magnetic structure producing an M6.5 flare in the active region 12371

  • Kang, Jihye;Inoue, Satoshi;Kusano, Kanya;Park, Sung-Hong;Moon, Yong-Jae
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.83.2-83.2
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    • 2019
  • We study the stability of the magnetic structure in active region (AR) 12371 producing an M6.5 flare on June 22 2015. We first perform a nonlinear force-free fields (NLFFFs) extrapolation to derive three-dimensional (3D) magnetic fields based on time series of observed photospheric magnetic fields. The NLFFFs well describe an observed sigmoidal structure with the shape of a double arc magnetic configuration. Next, we examine three possible instabilities (kink, torus, and double arc) to investigate how the M6.5 flare is triggered in the double arc loops. Consequently, the double arc loops are stable against kink and torus instabilities, but possibly unstable against the double arc instability before the flare occurrence. Finally, we discuss a probable scenario for the M6.5 flare.

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LuGre Model-Based Neural Network Friction Compensator in a Linear Motor Stage

  • Horng, Rong-Hwang;Lin, Li-Ren;Lee, An-Chen
    • International Journal of Precision Engineering and Manufacturing
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    • v.7 no.2
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    • pp.18-24
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    • 2006
  • This paper proposes a LuGre Model-Based Neural Network (MBNN) friction compensation algorithm for a linear motor stage. For matching the friction phenomena in both the motion-start region and the motion-reverse region, the LuGre dynamic model is employed into the proposed compensation algorithm. After training of the model-based neural network is completed, the estimated friction for compensation is obtained. From the obtained result we find that the new structure gains advantage over the non-friction compensation system on the performance of the compensator in both regions. The proposed compensator is evaluated and compared experimentally with an uncompensated system on a microcomputer controlled linear motor tracking system in the final section of the paper. The experimental results show the improvement on the maximum velocity error and the root mean square tracking error in the motion-start region ranges from 34% to 53% and from 53% to 75% respectively, and in the motion-reverse region from 48% to 65% and from 79% to 90% respectively.

The XP-table: Runtime-efficient Region-based Structure for Collective Evaluation of Multiple Continuous XPath Queries (The XP-table: 다중 연속 XPath 질의의 집단 처리를 위한 실행시간 효율적인 영역 기반 구조체)

  • Lee, Hyun-Ho;Lee, Won-Suk
    • Journal of KIISE:Databases
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    • v.35 no.4
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    • pp.307-318
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    • 2008
  • One of the primary issues confronting XML message brokers is the difficulty associated with processing a large set of continuous XPath queries over incoming XML seams. This paper proposes a novel system designed to present an effective solution to this problem. The proposed system transforms multiple XPath queries before their run-time into a new region-based data structure, called an XP-table, by sharing their common constraints. An XP-table is matched with a stream relation (SR) transformed from a target XML stream by a SAX parser. This arrangement is intended to minimize the runtime workload of continuous query processing. Also, system performance is estimated and verified through a variety of experiments, including comparisons with previous approaches such as YFilter and LazyDFA. The proposed system is practically linear- scalable and stable for evaluating a set of XPath queries in a continuous and timely fashion.

Effect of cylinder aspect ratio on wake structure behind a finite circular cylinder located in an atmospheric boundary layer (대기경계층 내에 놓인 자유단 원주의 형상비가 후류유동에 미치는 영향에 관한 연구)

  • Park, Cheol-Woo;Lee, Sang-Joon
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.247-252
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    • 2001
  • The flow around free end of a finite circular cylinder(FC) embedded in an atmospheric boundary layer has been investigated experimentally. The experiments were carried out in a closed-return type subsonic wind tunnel with varying aspect ratio of the finite cylinder mounted vertically on a flat plate. The wake structures behind a 2-D cylinder and a finite cylinder located in a uniform flow were also measured for comparison. Reynolds number based on the cylinder diameter was about Re=20,000. A hot-wire anemometer was employed to measure the wake velocity and the mean pressure distributions on the cylinder surface were also measured. The flow past the FC free end shows a complicated three-dimensional wake structure and flow phenomenon is quite different from that of 2-D cylinder. The three-dimensional flow structure was attributed to the downwashing counter rotating vortices separated from the FC free end. As the FC aspect ratio decreases, the vortex shedding frequency is decreased and the vortex formation length is increased compared to that of 2-D cylinder. Due to the descending counter-rotating twin-vortex, in the region near the FC free end, regular vortex shedding from the cylinder is suppressed and the vortex formation region is hardly established. In the wake center region, the mean velocity for the FC located in atmospheric boundary layer has large velocity deficit, compared to that of uniform flow.

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Structure Analysis of 16S rDNA Sequences from Strains of Acidithiobacillus ferrooxidans

  • Peng, Hong;Yang, Yu;Li, Xuan;Qiu, Guanzhou;Liu, Xueduan;Huang, Jufang;Hu, Yuehua
    • BMB Reports
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    • v.39 no.2
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    • pp.178-182
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    • 2006
  • Four strains of Acidithiobacillus ferrooxidans with different iron oxidation capacity were isolated from different mine drainage stations. The 16S rRNA gene of these strains were cloned and sequenced. Based on our sequences analysis on the four strain and the data on the other strains deposited in Genbank, all A. ferrooxidans may be classified into three phylogenetic groups. The analysis data showed that nucleotide variables (signature sites) were detected in 21 positions, and most of them were found in the first 800bp from 5' terminal except position 970 and 1375. Interestingly, the first 13 signature sites were located in two main regions:the first region (position 175-234) located in V2 while the second region (position 390-439) were detected in constant region between V2 and V3. Furthermore, the secondary structure and minimal free energy were determined in two regions among strains of three groups. These results may be useful in characterizing the microevolutionary mechanisms of species formation and monitoring in biohydrometallurgical application.

Nonlinear Diffusion and Structure Tensor Based Segmentation of Valid Measurement Region from Interference Fringe Patterns on Gear Systems

  • Wang, Xian;Fang, Suping;Zhu, Xindong;Ji, Jing;Yang, Pengcheng;Komori, Masaharu;Kubo, Aizoh
    • Current Optics and Photonics
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    • v.1 no.6
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    • pp.587-597
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    • 2017
  • The extraction of the valid measurement region from the interference fringe pattern is a significant step when measuring gear tooth flank form deviation with grazing incidence interferometry, which will affect the measurement accuracy. In order to overcome the drawback of the conventionally used method in which the object image pattern must be captured, an improved segmentation approach is proposed in this paper. The interference fringe patterns feature, which is smoothed by the nonlinear diffusion, would be extracted by the structure tensor first. And then they are incorporated into the vector-valued Chan-Vese model to extract the valid measurement region. This method is verified in a variety of interference fringe patterns, and the segmentation results show its feasibility and accuracy.

An Algorithm for generating Cloaking Region Using Grids for Privacy Protection in Location-Based Services (위치기반 서비스에서 개인 정보 보호를 위한 그리드를 이용한 Cloaking 영역 생성 알고리즘)

  • Um, Jung-Ho;Kim, Ji-Hee;Chang, Jae-Woo
    • Journal of Korea Spatial Information System Society
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    • v.11 no.2
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    • pp.151-161
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    • 2009
  • In Location-Based Services (LBSs), users requesting a location-based query send their exact location to a database server and thus the location information of the users can be misused by adversaries. Therefore, a privacy protection method is required for using LBS in a safe way. In this paper, we propose a new cloaking region generation algorithm using grids for privacy protection in LBSs. The proposed algorithm creates a m inimum cloaking region by finding L buildings and then performs K-anonymity to search K users. For this, we make use of not only a grid-based index structure, but also an efficient pruning techniques. Finally, we show from a performance analysis that our cloaking region generation algorithm outperforms the existing algorithm in term of the size of cloaking region.

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A Study on Village Names of Youngnam Provinces : the Cases of Changnyeong-Gun, Bonghwa-Gun and Namhae-Gun (영남지방 지명에 관한 연구 -창녕군, 봉화군, 남해군의 경우-)

  • Park, Tae-Hwa
    • Journal of the Korean association of regional geographers
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    • v.5 no.1
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    • pp.1-24
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    • 1999
  • This is a study on village names in a plain region of Changnyeong-Gun, a mountain region of Bonghwa-Gun and an island region of Namhae-Gun. The three regions differ in geographical features. The data are based on 455 village names in Changnyeong-Gun, 552 village names in Bonghwa-Gun and 275 village names in Namhae-Gun found in the 1 : 50,000 topographic map. The method of this study is to analyze the word structures of village names in the five basic concepts in geography : Man-Land(Natural Environment and Human Activities). Spatial Relation, Distribution, Region and Transition. The main results of this study are as follows: 1. Naming of villages are related to Natural Environment(41%), Human Activities(23%), Region(17%), Spatial Relation(13%), Distribution(5%), and Transition(3%). Of these six factors, Changnyeong-Gun is relatively dominant in village names related to Spatial Relations, Region and Transition ; Bonghwa-Gun Natural Environment and Namhae-Gun Human Activities and Spatial Relations. But the three Guns are absolutely dominant in village names related to Natural Environment and Human Activities. 2. A village name is divided into the specific name part(given name) and the generic name part(classified name). Names related to Human Activities, Spatial Relations, Distribution and Transition are more frequently found in the specific name part. Therefore, they are used as the given name of a village name. Whereas names related to Natural Environment and Region are more frequently found in generic name part, which means that they are used as the classified name of a village. 3. The word structure of a village name usually has two parts a frontal part(given name) and a rear part(classified name). The two parts have a particular pattern in the geographic concept when they are combined. 1) In the village names related to in their frontal part of the word structure, is more frequently combined as their rear part in Bonghwa-Gun, in Namhae-Gun and in Changnyeong-Gun. 2) In the village names related to in their frontal part of the word structure, is more frequently combined as their rear part in Changnyeong-Gun, in Namhae-Gun and in Bonghwa-Gun. Accordingly, Man(Human Activities) - Land (Natural Environment) can be considered the most important concept in the naming of villages, because the concept is most frequently used in the word structures of village names.

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The Effect of Quantum Well Structure on the Characteristics of GaN-based Light-Emitting Diode (양자 우물 구조가 GaN 기반 LED 특성에 미치는 영향)

  • Lee, Jae-Hyun;Yeom, Keesoo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.10a
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    • pp.251-254
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    • 2012
  • In this paper, the output characteristics of GaN-based LED considering quantum well structure are analyzed. The basic structure of the LED consists of active region of GaN barrier and InGaN quantum well between AlGaN EBL(Electron Blocking Layer) and AlGaN HBL(Hole Blocking Layer) on GaN buffer layer. The output power, internal quantum efficiency characteristics of LED active region considering thickness of quantum well, number of quantum well and doping of barrier are analyzed using ISE-TCAD.

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Heterogeneously Integrated Thin-film Lithium Niobate Electro-optic Modulator Based on Slot Structure

  • Li, Xiaowei;Xu, Yin;Huang, Dongmei;Li, Feng;Zhang, Bo;Dong, Yue;Ni, Yi
    • Current Optics and Photonics
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    • v.6 no.3
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    • pp.323-331
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    • 2022
  • Electro-optic modulator (EOM) takes a vital role in connecting the electric and optical fields. Here, we present a heterogeneously integrated EOM based on the lithium niobate-on-insulator (LNOI) platform. The key modulation waveguide structure is a field-enhanced slot waveguide formed by embedding silicon nanowires in a thin-film lithium niobate (LN), which is different from the previously reported LN ridge or etchless LN waveguides. Based on such slot structure, optical mode field area is reduced and enhanced electric field in the slot region can interact well with LN material with high Electro-optic (EO) coefficient. Therefore, the improvements in both aspects have positive effects on enhancing the modulation performance. From results, the corresponding EOM by adding such modulation waveguide structure achieves better performance, where the key half-wave-voltage-length product (V𝜋L) and 3 dB EO bandwidth are 1.78 V·cm and 40 GHz under the electrode gap width of only 6 ㎛, respectively. Moreover, Lower V𝜋L can also be achieved. With these characteristics, such field-enhanced waveguide structure could further promote the development of LNOI-based EOM.