1,721,001 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Detecting Channel Occupancy Time Pattern using WiFi Adapters
Get PDF학위논문 (석사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 2. 최성현.IEEE 802.11 표준에 의거한 무선랜 (Wireless LAN) 기술은 등장 초기부터 빠르게 보급되었으며, 최근 몇 년 동안에 급성장한 스마트폰과 태블릿PC에도 대부분 탑재되어 현재 본연의 네트워크 연결 제공 기능 뿐만 아니라 모바일 네트워크 트래픽 분산 등의 역할도 담당하고 있다.
802.11 표준은 지금까지도 매우 활발하게 발전되고 있는데, 이렇게 무선랜 표준이 발전할 수 있었던 것은 학계와 칩셋/기기 제조사들의 활발한 연구 덕분이라고 할 수 있고, 특히 최근에는 상용 장비를 활용하여 실측 기반의 실험 결과를 연구에 활용하는 사례가 늘어나고 있다.
이 논문에서는 상용 장비를 이용한 측정 방법의 하나를 구현하고 그것을 활용하는 것에 대해 논한다. 먼저 이 논문의 구현과 비교대상으로 사용될 수 있는 AirPcap 과 Wireshark 을 이용한 패킷 포획 시 각 패킷의 타임스탬프 (timestamp) 가 정확하게 얻어지지 않는 현상에 대해 분석하고, 다음으로 이 논문의 구현에 대하여 설명한다. 마지막으로 이 논문의 구현을 활용하여 대역폭 예측 (Bandwidth Estimation) 을 구현한 방법을 설명하고, 대역폭 예측 실험 결과를 다른 비교 결과 & 실제 대역폭과 비교했을 때의 결과를 설명하고 마무리한다.초록 i
제 1 장 서론 1
제 2 장 기존 측정 장비의 문제점 3
2.1 AirPcap (USB) + Wireshark (on Windows) 3
2.2 AR5BHB112 (PCI-Express) + Wireshark (on Linux) 7
제 3 장 점유 시간 탐지 (Occupancy Pattern Detection) 알고리즘 9
3.1 채널 점유 패턴 (Channel Occupancy Pattern) 9
3.2 채널 점유 패턴을 구하는 원리 9
3.3 측정 시에 발생하는 Busy / Idle Glitch 11
3.4 채널 점유 패턴을 구하기 위한 Finite State Machine 13
3.5 제안하는 OPD 를 이용한 측정 결과 15
제 4 장 구현의 활용 - 대역폭 예측 18
4.1 대역폭 예측 (Bandwidth Estimation) 18
4.2 유효 점유 패턴 (Effective Occupancy Pattern) 19
4.3 Channel Occupancy Pattern 을 이용하여 대역폭을 예측하는 방법 20
4.4 대역폭 예측 실험과 그 결과 21
제 5 장 결론 28
참고 문헌 29
ABSTRACT 32
감사의 글 34Maste
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
성층권에서의 행성파의 변화와 극와동의 붕괴
Get PDF학위논문(박사) -- 서울대학교대학원 : 자연과학대학 지구환경과학부, 2022. 8. 최우갑.The polar vortex and planetary waves are important dynamical phenomena in the winter stratosphere, which dominate large-scale circulation, tracer distribution and ozone depletion, and stratosphere-troposphere coupling. This study explored the evolution and interannual variability of the polar vortex and planetary waves, focused on the seasonal transition period in the Northern Hemisphere (NH) spring, using the ERA-Interim reanalysis data for 1979–2018.
In terms of polar vortex and breakup in NH seasonal transition to spring, conventional diagnostics used threshold values of potential vorticity (PV) or zonal wind speed based on the lower stratospheric polar vortex. Those diagnostics cannot be applied to the upper stratospheric polar vortex, of which evolution of PV is more complicated and zonal wind speed is much higher to prescribe the threshold values. In this study, the dates of polar vortex formation and breakup could be newly defined without prescribing threshold PV or zonal wind speed, based on the temporal change in the new edge-change metric, which is the average of the rates of changes in area-equivalent latitude, PV, and zonal wind speed at the edge of the vortex.
By applying the new diagnostic, the formation and breakup dates of the polar vortex for the whole stratosphere were obtained and compared to the dates of the stratospheric final warming. To see if the new diagnostic is consistent with tracer transport near the vortex edge, the formation and breakup of the polar vortex were compared with the zonal standard deviation of the mixing ratios of long-lived trace species. It turned out that the newly defined polar vortex breakup dates well match the changes in the mixing ratio of the trace gases in the stratosphere for the winter. Considering all the above observations, the new diagnostic for vortex formation and breakup appears to be applicable to the whole stratosphere.
In terms of interannual variability of the stratospheric planetary waves in NH spring, the development of large-amplitude planetary waves in March in the upper stratosphere was investigated. During the 10-hPa easterly QBO, the geopotential height wave number 1 (wave-1) amplitude at 3 hPa was significantly larger than that during the westerly QBO for cases of large-amplitude planetary waves. Case studies on an easterly QBO case in 1994 and a westerly QBO case in 1995 were conducted for individual events of the wave-1 planetary wave growth. During the easterly QBO in March 1994, a developing perturbation at middle latitudes moved rapidly northeastward to replace the decaying high-latitude wave. In the early stage, the zonal-mean-to-eddy kinetic energy conversion in the subtropical region was crucial for wave development. This energy conversion was related to the negative meridional shear of the zonal wind in the middle latitudes. Negative meridional zonal wind shear was produced by the secondary meridional circulation associated with the equatorial QBO. After the perturbation started to develop in the middle latitudes, it moved northeastward over a few days due to potential vorticity flux, and the growth of the high-latitude waves was enhanced.
Composite analyses indicate that the dynamical characteristics of wave-1 growth found in March 1994 can be found in March in the easterly QBO years. The composite analysis also showed that the meridional shear of the zonal wind in the middle latitudes was negative during the easterly QBO in March and plays an important role in developing the high-latitude wave-1 planetary wave. The dynamic response of the planetary waves to different QBO profiles was further examined by the general circulation model (GCM) experiments. The result shows the larger wave-1 amplitude and a similar wave-1 growth pattern in the easterly QBO experiments in April instead of March, probably due to the longer and colder winter in the GCM climatology. This study implies an important role of internal dynamics related to the QBO in developing planetary waves in the seasonal transition period when the influence of the vertical propagation of planetary waves is relatively weak.극와동과 행성파는 대규모순환, 미량기체의 분포 및 오존감소, 성층권–대류권 상호작용에 영향을 미치는 겨울철 성층권의 대표적인 역학적 현상이다. 본 연구에서는 1979년부터 2018년까지의 ERA-Interim 재분석 자료를 이용해 북반구 봄철 계절변화 시기의 극와동과 행성파의 변화 및 경년변동을 분석하였다.
북반구의 겨울에서 봄으로의 전환기의 극와동 및 극와동 붕괴에 대한 기존의 진단법들은 주로 하부성층권 극와동의 특성에 기반한 와도 또는 동서풍속의 특정 임계값을 사용하여, 극와동의 변화 양상이 복잡하고 동서풍속이 훨씬 큰 상부성층권에는 적용하기 어려웠다. 본 연구에서는 극와동의 생성 및 붕괴 시기를 미리 정의한 특정 임계값을 사용하지 않고, 극와동의 경계에서의 상당위도, 와도, 동서풍속의 시간변화율의 평균인 edge-change 메트릭의 변동을 통해 정의하였다.
새 진단법을 적용하여, 성층권 전체에 대한 극와동의 형성 및 붕괴 시기를 구하고, 이를 최종승온과 비교하였다. 새로운 진단법이 극와동 경계에서의 미량기체 수송 양상과 일치하는지 확인하기 위해 극와동의 생성 및 붕괴 시기를 미량기체 혼합비의 동서표준편차와 비교한 결과, 새로 정의된 극와동 붕괴 시기가 성층권 미량기체 혼합비의 변화와 잘 일치함을 확인하였다. 이러한 관찰로부터, 극와동 생성 및 붕괴에 대한 새 진단법은 하부성층권과 상부성층권을 포함한 성층권 전체에 적용 가능한 것으로 보인다.
북반구 봄철 성층권 행성파의 경년변동 측면에서 3월 상부성층권의 행성파 발달을 조사한 결과, 3 hPa의 파수 1 행성파는 그 진폭이 큰 해들 중 적도 성층권 준2년주기진동 위상이 10 hPa에서 동풍인 경우 서풍인 경우에 비해 유의미하게 큰 진폭이 나타났다. 준2년주기진동의 위상이 동풍이었던 1994년 3월과 서풍이었던 1995년 3월에 대해 실시한 파수 1 행성파 발달 사례연구에서, 1994년 3월 사례에는 중위도의 섭동이 북동쪽으로 빠르게 이동하여 발달하여 고위도의 파동을 대체하였다. 행성파 발달 초기단계에서 아열대의 동서평균운동에너지의 에디운동에너지로의 변환이 중위도 섭동의 발달에 있어 중요하며, 이러한 에너지변환은 중위도의 음의 동서풍 남북경도와 관련이 있다. 음의 동서풍 남북경도는 준2년주기진동에 의한 자오면 2차순환에 의해 생성된다. 중위도로부터 발달하기 시작한 섭동은 잠재와도속에 의해 수일에 걸쳐 북동쪽으로 이동하며 고위도 행성파의 성장을 더욱 강화시킨다.
합성분석은 1994년 3월의 파수 1 행성파 성장의 역학적 특성이 준2년주기진동의 동풍인 해들의 3월에 공통적으로 나타남을 보여주며, 음의 동서풍 남북경도가 고위도 파수 1 행성파의 발달에 중요함을 보여준다. 준2년주기진동의 적도 동서풍 프로파일에 따른 행성파의 역학적 반응을 대기대순환모형을 통해 조사한 결과, 4월에 준2년주기진동의 동풍 프로파일을 이용한 실험의 파수 1 행성파의 진폭이 서풍 프로파일을 이용한 실험에 비해 유의미하게 컸으며, 행성파의 발달 패턴 역시 재분석자료의 3월 패턴과 유사하였다. 이는 대기대순환모형의 겨울이 관측에 비해 더 길고 추운 것에 기인한 것으로 보인다. 본 연구는 행성파의 연직전파가 상대적으로 약한 계절전환기의 행성파 발달에 있어 적도성층권 준2년주기진동과 관련된 내부역학의 중요한 역할을 시사한다.Abstract i
Table of Contents iv
List of Figures vi
List of Tables xvi
1. Introduction 1
2. Data and Model 8
2.1. Reanalysis Data 8
2.2. Satellite Tracer Data 9
2.3. General Circulation Model 11
3. Evolution and Breakup of Polar Vortex 12
3.1. Conventional Diagnostics of Polar Vortex 12
3.1.1. Polar vortex in the lower stratosphere 12
3.1.2. Polar vortex in the upper stratosphere 19
3.2. Edge-change Diagnostic for Polar Vortex 23
3.2.1. Edge-change metric 23
3.2.2. Comparisons with conventional diagnostics 28
3.2.3. Application of edge-change diagnostic 33
3.3. Validation of Edge-change Diagnostic 36
3.3.1. Breakup of polar vortex and SFW 36
3.4.2. Tracer distributions 41
4. Stratospheric Planetary Waves in NH Spring 47
4.1. Interannual Variability in Planetary Waves 47
4.1.1. Climatological characteristics 47
4.1.2. Interannual variability in wave-1 amplitude and QBO 51
4.2. Case Study: Planetary Wave Development in March 1994 and 1995 57
4.2.1. Daily evolution of wave-1 growth 57
4.2.2. Eddy forcing 62
4.2.3. Potential vorticity and enstrophy 66
4.2.4. Eddy kinetic energy 72
4.3. Composite Analysis: Daily Evolution of Planetary Waves and QBO 77
4.3.1. Identification of wave-1 growth events 77
4.3.2. Response of wave-1 growth to QBO 81
4.3.3. Kinetic energy conversion 89
4.4. Dynamic Mechanism of QBO Modulation on Planetary Waves in NH Spring 93
4.4.1. Secondary meridional circulation 93
4.4.2. General circulation model simulations 103
5. Summary and Conclusions 116
References 123
국문초록 132박
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
