17505 research outputs found
Sort by
再生可能エネルギー大量導入時の需要家側資源を用いた分散型電源の安定運用方式および需給協調制御方式の開発
Get PDF地球温暖化対策としての二酸化炭素排出量削減に向けて，再生可能エネルギーの導入拡大が図られている。これまで，固定価格買取制度の導入により太陽光発電を中心として再生可能エネルギーの導入拡大が図られてきたが，再生可能エネルギーは発電電力が気象条件によって変動するため，これにより電力系統の周波数変動や電圧変動，および系統全体で余剰電力が生じ，電力系統の安定運用に影響を与えることが懸念されている。
これらの課題に対して，系統側での対策としては蓄電池の設置により周波数・電圧変動を抑制し，余剰電力を抑制することが考えられる。しかし，このための対策コストは非常に高 コストとなることが懸念される。一方で，近年，デマンドレスポンス (DR) やバーチャルパワープラント (VPP) 等，需要家側資源（非常用発電設備や蓄電池，ヒートポンプ式給湯機など）を活用して電力系統の需給運用に貢献する技術の開発・実証が行わ
れており，このための調整力市場も整備されつつある。これら需要家側資源を活用した制御技術と，従来の系統側の発電機制御技術を協調させることで，再生可能エネルギー大量導入に対応するための必要な対策コストを低減できる可能性がある。
本研究では，再生可能エネルギー大量導入時の系統周波数・電圧変動，および余剰電力を抑制するための，電力系統側の発電機による周波数・電圧制御と需要家側資源を活用した需要家機器制御との協調制御システムを検討し，提案システムの有効性をシミュレーションと一部実験により検証した。
先ず，事業者がレジリエンス向上や事業継続計画 (BCP) の観点から導入するガスタービン発電機等の非常用発電設備を需要家側資源として活用し，常時の運用において同時同量制御を行うことにより系統の需給バランス維持に貢献する手法を検討した。
次に，系統側および需要家側に蓄電池を設置し，既存の系統側発電設備の周波数・電圧制御との協調により，より少ない蓄電池容量で再生可能エネルギーの出力変動による系統周波数，電圧変動を抑制する協調制御手法を検討した。
さらに，再生可能エネルギー大量導入による系統全体の余剰電力を抑制するため，配電用変電所に蓄電池を設置し，同時に配電用変電所の潮流平準化制御を実施することで配電系統の設備スリム化にも寄与する，配変潮流平準化制御手法を検討した。
最後に，余剰電力をより低コストで抑制するため，住宅のヒートポンプ式給湯機を活用し，再生可能エネルギー発電予測の不確実性と需要家の便益（電気代低減や湯切れ防止）を考慮しながら，余剰電力を抑制する需要家機器運転計画手法を検討した。
上記で提案した各手法の有用性を数値シミュレーションと一部実験により検証するとともに，各手法の実用化に向 けた課題（機器コス ト低減や市場の整備等）を整理した。博士（工学）琉球大
Studies on the coral-killing sponge Terpios hoshinota in Okinawa Island, Japan
Get PDFCoral reefs are facing serious threats in decades due to climate change or competition with other organisms. The coral-killing sponge Terpios hoshinota Riitzler & Muzik 1993 can cover huge areas of corals. Studies on the biology and ecology of this cyanobacteriosponge is scarce. The aim of this research addresses the gaps in understanding the biology and ecology of T. hoshinota in Okinawa Island, Japan.
Although the morphological components of the sponge such as cyanobacteria, spicules and particles are crucial, accurate quantitative measurements have not been estimated. In Chapter 2, the density of symbiotic cyanobacteria was carried out with grinding method showing higher density than previous report. Similarly, densities of spicules and particles were estimated by bleaching method. Spicule length of Sesoko sponge was shorter (193 μm) compared to other sites in previous studies. This sponge selects specific size particles (22.3 μm in diameter) from surrounding water. Moreover, spicules size and composition of particles were analyzed and discussed in relation to composition of sediments around the sponge (Chapter 3). The rate of acid-insoluble matter in sediments was higher in northern site of Okinawa Island, suggesting the plasticity of morphological components and surrounding environmental factors.
Despite of its importance, the in site progression of T. hoshinota remained unclear. Therefore, the monthly progression rates of T. hoshinota were measured over a year (Chapter 4), the results showing higher progression in summer (July, August, and October) with a mean value of 66 mm month^, except in September, when strong typhoons come close to Okinawa and the progression rate decreased temporarily. For sponge reproduction, the development of gametogenesis and embryogenesis through histological examination were determined together with the experiment of field larval settlement (Chapter 5). The results showed that the higher number of larval settlements might depend on the topography of location and be affected by the event such as typhoon. In Chapter 6, monthly observations on the maturity stages categorized as the position of sponge larvae were carried out (May 2021 - May 2022), showing different patterns in different sites. Environmental differences such as temperature fluctuation due to reef structures were suggested.
Sponge-associated snail was identified as Joculator sp. (family Cerithiopsidae) (Chapter 7).
The present study elucidated the fundamental survival strategy of T. hoshinota in relation to environment in subtropical coral reefs in Okinawa Island, Japan.博士（学術）琉球大学University of the Ryukyu
Knowledge, attitudes, arid practices of public secondary school teachers on Zika Virus Disease: A basis for the development of evidence-based Zika educational materials for schools in the Philippines
Get PDFThe Philippines is at risk in developing a Zika Virus (ZIKV) Disease Outbreak. One of the possible interventions is health education because students are potential health advocates and influencers to their communities through the knowledge transfers from their teachers. The competency of Filipino teachers on ZIKV Disease is yet to be described. This study aimed to assess the knowledge, attitudes, and practices of public secondary school teachers on ZIKV Disease. A modified version of the Knowledge, Attitudes, and Practices Survey Tool on Zika Virus Disease from the World Health Organization—Pan American Health Organization (WHO-PAHO) was used to assess the knowledge, attitudes, and practices of teachers of eight public secondary schools in five villages in Quezon City, Philippines. Out of the 609 respondents, 87.3% reported that their main source of information about ZIKV is tri-media, which includes television, print, and radio. Majority of the respondents mentioned that ZIKV is transmitted through a mosquito bite (80.3%). However, only half of the participants identified vector control as a preventive strategy. Moreover, only 54% admitted to have cleaned their water containers or water sources within the last week. Only a few identified mother-to-child (23%) and sexual intercourse (8%) as other means of transmission. Half (49.8%) of the respondents felt that it is possible to acquire ZIKV in their community, while 90% perceived that a private doctor (90%) or a public hospital (88%) can effectively treat the disease. Perceived stigma is high at 50%. This study showed there was good knowledge among teachers on vector transmission of ZIKV but poor knowledge on other aspects of the disease. Also, there was a low level of perceived susceptibility and severity of ZIKV which can be explained by the absence of a personal encounter with a Zika patient and the low number of cases in the Philippines. Half of the respondents said that they cleaned the possible mosquito breeding sites within the last week, followed by those who cleaned their water source more than a week ago (19%). None of the socio-demographic characteristics is significantly associated with respondents’ knowledge on Zika. Only income and location of residence were found to be significantly associated with attitudes towards Zika. These findings call for a comprehensive training program that includes development of teaching materials for public secondary school teachers on ZIKV Disease based from this study.フィリピンは、ジカウイルス感染症の流行が発生するリスクの高い国である。ジカウイルス感染症の可能な対策の一つに生徒に対する健康教育がある。生徒は教師から得た知識を地域に伝達することにより、地域への潜在的な健康擁護者であり影響力を持つ存在といえるからである。しかし、フィリピンの教師のジカウイルス感染症に関する行動特性は明らかではない。本研究の目的は、公立中学校教師のジカウイルス感染症に対する知識、態度および実践に関し、て評価することである。フィリピンのクエゾン市内の5村にある8中学校に働く教師を対象として、WHO-PAHOが発行するジカウイルス感染症における改訂版KAP調査表を用いて評価を行った609名の参加者のうち、87.3％の教師が、ジカウイルスに関する主な情報源は、テレビ、活字媒体、ラジオを含んだトリメディアであると回答した。大部分の参加者は、ジカウイルスは蚊の媒介により感染すると答えた (80.3%) が、予防策としてベクターの制御を挙げたのは半分ほどだった。加えて、一週間以内に水を入れる容器や水源の掃除をしたものは、54％のみだった。他の感染経路として母子感染と性行為を挙げた参加者は、それぞれ23％と8％でわずかだった。半数の参加者は、ジカウイルスは地域で感染する可能性があるとしている一方で、 90％の参加者が開業医（90%）や公立の病院（88%）で効果的な治療を受けることができると回答した。認識されるステイグマは50％と高かった。本研究では、ジカウイルスの病原媒介に対する教員の知識は高かったが、その他の側面に関しては知識が乏しかったことが示された。また、ジカウイルスの感受性や重症度における認識は低いことがわかった。これはジカウイルス感染者と接触したことのある対象者が少なく、またフィリヒ°ン内での患者数が少ないことによると説明できる。一週間以上前に水源の掃除をしたと答えた 19％の対象者のうち、半数が一週間以内に蚊の繁殖する可能性のある場所を掃除したと答えている。社会人口学的特性のいずれも、対象者のジカウイルス感染症に関する知識と有意に関連はなかった。収入と居住のみがジカウイルス感染症に対する態度と有意に関連していた。この研究結果よりジカウイルス感染症に関連した公立中学校の教師向けの教材の開発を含む包括的なトレーニングプログラムの必要性が示唆された。博士(保健学)琉球大
成人 T 細胞白血病・リンパ腫における生検組織を用いた新規診断アルゴリズム ： HTLV-1 に対する RNA in situ hybridization と定量 PCR の組み合わせ
Get PDFHistopathological distinction between adult T-cell leuketnia/lymphoma (ATLL) and other T-cell neoplasms is often challenging. The current gold standard for the accurate diagnosis of ATLL is the Southern blot hybridization (SBH) assay, which detects clonal integration of human T-cell leuketnia virus type I (HTLV-1) provirus. However, SBH cannot be petformed with small biopsy or formalin-fixed paraffin-embedded (FFPE) tissue samples because this assay requires a large amount of DNA without degradation. Here we developed a new diagnostic algorithm for the accurate diagnosis of ATLL using FFPE samples. This method combines two HTL V-1 detection assays, namely, ultrasensitive RNA in situ hybridization using RNAscope for HTLV-1 bZIP factor (HBZ-RNAscope), and quantitative PCR targeting the tax gene (tax-qPCR). We analyzed 119 FFPE tissue specimens (62 ATLL, and 57 non-ATLL, including 41 HTLV-1 carriers) and compared them with the SBH results using the corresponding fresh-frozen samples. As a result, tax-qPCR had a higher ATLL identification rate than HBZ-RNAscope (88% [52/59], and 63% [39/62], respectively). However, HBZ-RNAscope clearly visualized the localization of HTLV-1-infected tumor cells and its identification rate increased to 94% (17/18) when the analysis was limited to samples up to 2 years old, indicating its usefulness in the daily diagnosis. The diagnostic algorithm combining these two assays successfully evaluated 94% (112/119) of samples and distinguished ATLL from non-ATLL cases including HTLV-1 carriers with 100% sensitivity and specificity. This method is expected to replace SBH and increase the accuracy of the diagnosis of A TLL.博士(医学)琉球大
需要側管理を考慮したマイクログリッドの技術経済学、最適化、および回復力
Get PDFFossil-fuel generation technologies have been the most popular choice for supplying energy because of their low initial cost, flexibility of operation, and scalability. However, due to the scarcity of fossil fuel supplies, as well as environmental concerns and techno-economic viability, cleaner generation technologies based on wind, solar, hydro, and hydrogen are being strongly emphasized and supported throughout the world. As a result, integrating these technologies has become a priority for microgrids, and their ability to operate with or without the main grid makes them one of the most intriguing research topics today. The major goal of microgrids or hybrid energy systems is to provide local, dependable, and affordable energy security for urban and rural areas, as well as solutions for commercial, industrial, arid federal government clients, especially when the utility power supply is not available. Lowering greenhouse gas (GHG) emissions and reducing stress on the transmission and distribution system are two benefits from the deployment of microgrids that extend to utilities and the community as a whole. Integration and coordination of renewable energy technologies with conventional power generators presents significant challenges in terms of reliable operation, energy management, and control. These issues can be exacerbated by the presence of multi-energy load demand (such as heating plus electrical) and a variety of demand side measures, such as electric vehicles and demand response schemes. Furthermore, given the world's frequent natural disasters, ensuring the resilience of power and energy supply networks, particularly for microgrids, has never been more important than now. This thesis attempts to address these issues by designing the optimal microgrid system. The optimal and intelligent dispatch strategy of the microgrid is also discussed in different weather and loading condition. As for demand side management, a time of use (ToU) demand response strategy is proposed and an electric vehicle (EV) charging station connected to the microgrid is considered. Integrating diverse energy sources, such as electricity, heat, and electrified mobility, presents several potential and obstacles. The optimization and simulation studies have been carried out using the different well-known tool-MATLAB, HOMERpro, and Python based Pyomo.博士（工学）琉球大
再生可能エネルギー電源の導入による電力系統負荷周波数制御手法
Get PDFIn most remote and isolated areas, electric power is often supplied by diesel generators. However, diesel generators cause serious impacts on the environment as every little of diesel releases about three kilograms of CO_2. Also, diesel is expensive because transportation to remote area adds extra cost. Moreover, diesel generators are inherently inefficient when operating at a low load factor (below 40%-50% of their rated capacity). Due to these environmental and economic influences of the diesel generator, the environment pollution had been attracting most researchers' attention recently, and it is solved by renewable energy sources (RESs) as an alternative to non-renewable sources. Among them, Wind, solar, sea, biomass, and geothermal powers are sustainable and clean sources. Wind and solar attracted a lot of attention nowadays and became the most widely utilized renewable energy sources in power systems. Also, fuel cell (FC) could be considered as one of the green power sources of the future. However, the sharp fluctuations in the generated power of RESs devices caused by conditions of weather, temperature and season leads to the deterioration of the supply-demand balance, which may also affect the systems stability and reliability, especially in isolated systems with renewable energy sources such as WTG and PV, faces some stability problems because the power supplied by these sources is not constant, diverges quickly and cannot be easily predicted. So, these oscillations in the renewable power sources can produce instantaneous mismatch in the vital balance between generation and demand. Consequently, continuous variations in frequency and voltage levels usually appear which negatively affect the electric power system stability. Therefore, a continuous control for the supplied power by these renewable sources is required to ensure robust performance of the power system.
One of the most serious problems in power system is frequency deviation. In small-scale and isolated power system like isolated islands power system or remote areas power system, the output power fluctuation of RESs causes a huge frequency fluctuation. The fluctuation in system frequency causes the supply unstable and large-scale blackout in the worst case. To eradicate the frequency fluctuation phenomenon, power deviation needs to be controlled. Many research efforts have been conducted based on the load frequency control methods using battery technology. However, it is hard to compensate the supply-demand balance by using batteries, since the implementation cost of the battery is high. In order to increase the penetration of RESs in the future power system, a system frequency control method is necessary.博士（工学）琉球大
都市および農村地域の土地利用計画適正化に関する研究：カブール首都圏域を対象として
Get PDFThe capital of Afghanistan, Kabul has gone through the most powerful wave of urbanization since 2003. The population increased by almost 10% per year, which eventually contributed to a large urban sprawl and illegal settlements on the hill sides and the city. Most of the settlements are prone to natural disasters and may cause casualties and extensive damages if not paid attention.
Kabul Metropolitan Area (KMA), with a total area of 1763 km2, has been chosen as the study area. It encompasses both the existing Kabul and Kabul New City (KNC). The master plan for the KNC which is also known as Dehsabz area was prepared with the cooperation of JICA. Planners faced several challenges while designing the new city as the land already contained 54 villages and, more importantly, 140,000 people were residing there. Given their socioeconomic significance and critical role in urban-rural jntegration, it was necessary to preserve and upgrade them. To define a sustainable model for the development of the villages, essentially, there is a need for characterization and categorization of the villages. Following a literature review on multi-criteria decision analysis and AHP approaches, efforts have been placed to classify the villages from several planning aspects; seven potential factors with 36 sub-parameters were identified and rated in collaboration with experts, and super decision software was used as an analytic hierarchy process (AHP) tool to weight the factors. The result revealed that almost two of the entire villages have the highest development capacity while another two villages have the lowest. Furthermore, 8, 9, and 15 villages have been classified respectively into high, moderate, and low categories. The third part of the dissertation primarily evaluates land suitability from an environmental and physical perspectives as a tool for determining appropriateness for urban development in the existing Kabul city. The focus was centred on the application of the AHP and MCDA through GIS. Twelve principal factors with 43 sub-parameters including landslides, avalanches, earthquakes, floods, groundwater, and climate, along with other physical and geological factors like soil, slope, natural features, historical and cultural sites, landcover, and barren land, were identified to be weighted in collaboration with experts. The result showed that 22.9% of Kabul is highly suitable, while 28.1%, 17.5%, and 18.4% are classified respectively as suitable, moderate, and less suitable areas. However, 13.2% is ranked unsuitable, whereby factors such as slope, natural features, and landslides contribute most to the unsuitability. The resulting information from this research will assist urban planners and policymakers in determining the most effective use of land, as well as the protection of human lives and the environment.
For the research validation, a part of the existing Kabul has chosen as target area. The research primarily focused on three different development approaches and reveals that urban development methods are too dependent on a variety of factors, including the environmental, socio-economic, cultural, and physical conditions of each location. So that each area and region must be characterized and addressed by a specific development model that is consistent with the characteristics of the area.博士（工学）琉球大
持続可能な電化のためのハイプリッド再生可能エネルギー源の技術経済モデリングと最適化
Get PDFThis thesis considers the optimization of various Distributed Energy Resources to supply reliable power to Microgrids in various case study regions. In Chapter 1 (one), an introduction is presented on the actual scenarios of the energy situations that are to be investigated. Chapter 2 (two) investigated an Islanded Complementary Power System of the Bo-Kenema power network. The addition of high efficiency turbines to the optimum scenario reduced the COE and NPC costs by 38.9% and 39.1% respectively, while increasing CO_2 emissions by 49.9%. In chapter 3 (three), a decision-making exercise by the Government of Sierra Leone led to the optimum scenario being the most sustainable configuration. A multi-attribute decision making approach considering weight assignment used in Chapter 4 (four) resulted to an optimum configuration for electrifying Banana Island. By using different scheduling approaches, solar tracking systems and PV modules in Chapter 5 (five), the optimum configuration increased PV production by 28% which led to a huge reduction in costs.博士（工学）琉球大