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高密度プラズマ下で大電力マイクロ波放射を行うアンテナ表面の放電現像
Get PDF九州工業大学博士学位論文 学位記番号:工博甲第368号 学位授与年月日:平成26年3月25日1. Introduction||2. Experiment and Measurement||3. Experiment Result||4. Discussion||5. Conclusion||Appendix||References||Acknowledgement||Achievements of ResearchesThe space solar power system (SSPS) transfers enormous amounts of electrical energy through microwave or laser. SSPS must have very large and light-weight structures to collect the solar energy. The surface is covered with solar photovoltaic cells to collect and transform the incoming solar radiation into DC electricity. The transmission to ground would be performed with microwaves. Considered microwave frequency is 5.8 GHz. For conversion a large number of active elements together with carbon-fiber slotted wave guides or patch/microstrip antennas may be used. Flight demonstration onboard a small satellite in low Earth orbit (LEO) is now under consideration. When high-power microwaves are irradiated from an antenna in LEO plasma environment, there is a concern about multi-pactoring discharge caused by interaction between the plasma and the microwaves. There has been no experimental observation of such an interaction phenomenon. Verification experiments are essential for SSPS to become a reality. We have set-up an experimental system that can simulate the radiation of high power microwave in dense plasma in a vacuum chamber. A RF plasma source is installed to the chamber and can now produce the Argon plasma environment of density from 1011 to 1013m-3 with 4eV to 6eV temperature under a back pressure of 1.9x10-5Pa. A patch antenna with Teflon or Glass epoxy substrate has been installed inside the vacuum chamber. The antenna is connected to a magnetron that can produce 5.8GHz microwave up to 400W continuous power. I examine interaction between patch antenna surface and microwave in a vacuum chamber. I observe discharge on the patch antenna depending on the microwave strength and plasma environment. This thesis is made of five chapters. The first chapter introduces the general objective of study. The second chapter describes the experimental experimental setup and procedure. The third chapter reports the experimental results. The fourth chapter compares a hypothesis about the discharge inception mechanism against the experimental results. The fifth chapter concludes the paper with suggestions to the future works
分散型係数図形法に基づく電力系統のロバスト周波数制御系設計
Get PDF九州工業大学博士学位論文 学位記番号:工博甲第389号 学位授与年月日:平成27年3月25日Chapter 1: Introduction||Chapter 2: Frequency Control in Power System||Chapter 3: Coefficient Diagram Method||Chapter 4: First Case Study: Application of CDM to Interconnected Power System for Decentralized Frequency Control||Chapter 5: Wind farm Integration to Power System||Chapter 6: Smoothing Output Fluctuations in Power Systems with Wind Farms By Using Coefficient Diagram Method||Chapter 7: Conclusion||Chapter 8: List of Papers||Chapter 9: Biography of the AuthorIn an interconnected power system, area load change and abnormal conditions leads to mismatches within the system. Also, in recent years, renewable energy systems (RES) such as Wind Energy Systems (WES) has become the most popular renewable energy based generations. However, output fluctuations of WES can create imbalance between supply and demand. This imbalance can cause network frequency variations in power systems and thus reduce the power quality.
To alleviate the mentioned problems, a control system is required to suppress the frequency fluctuations or oscillations caused by integrations of renewable energy sources and sudden load changes. Since, Proportional Integral (PI) controller cannot work under certain operating conditions, and due to problems of calculation burdens associated with the algorithms of other advance robust controllers such as Model Predictive Control (MPC), it is necessary to implement a controller that is simple and reliable.
The standard Coefficient Diagram Method (CDM) developed by Professor Shunji Manabe has an advantage because it is simple and robust, and solves the problem of calculation burden associated with MPC. But when the CDM is implemented for power system control, then problem of parameters’ tuning exist. One important aspect of the CDM is the stability indices. When using CDM for power system frequency control, the standard values for the stability indices cannot work. Therefore, they must be changed. However, changing the stability indices can be done based on experience or by trial and error; and this becomes a problem for new power system control designers. Hence, this work modifies the standard CDM by introducing feed forward and feedback compensators to compensate for deficient performances. The technique is proposed as a new frequency control scheme using the Coefficient Diagram Method as a decentralized robust controller, in various test scenarios; considering varieties of power system configurations.
A three area interconnected power system is modelled, and this power system is assumed to be similar to the upcoming power system approved by the African development bank; which will interconnect Liberia, Guinea and Sierra Leone. These countries utilize hydro and steam turbines within their respective areas, but the problem of poor power quality which is highly related to frequency control requires attention. In this work, it is assumed that each country represents one area. Then, a three area power system assumed similar to their interconnection is modelled. With that, the proposed CDM is then implemented as control strategy to promote reliable electric power distributions.
Digital simulations of various case studies are provided to validate the effectiveness of the proposed scheme. From the simulation results, it is shown that, considering the overall closed-loop system performance with the proposed CDM technique, robustness is demonstrated in the face of uncertainties due to governors and turbines parameters variation and loads disturbances. A performance comparison between the proposed controller, model predictive controllers (MPC), and a classical proportional integral control (PI) scheme is carried out, confirming the superiority of the proposed CDM technique
Analysis of intensity of singular stress field for single lap joint under tensile shear load based on crack tip stress method
Get PDFIn this paper, the crack tip stress method (CTSM) is extended so that the intensity of the singular stress field of the single lap joint (SLJ) with two real stress singularity orders can be analyzed. Two types of the reference models are proposed; one is the tensile force model; the other one is the shear force model. The intensities of the singular stress field of the SLJ are calculated by superposing those of the reference models. The intensities of the singular stress fields of the reference models are calculated by the reciprocal work contour integral method (RWCIM). Then the validity of the reference models and the accuracy of the present method are discussed by comparing the present results with the solutions which are calculated by the RWCIM
Analysis on intensity of singular stress for bonded pipe in comparison with bonded plate
Get PDFProceedings of the 3rd International Conference on Fracture Fatigue and Wear, EEW2014, Kitakyushu, Japan, 1-3 September 2014In our previous research, the intensity of singular stress at the end of interface for bonded plate
was discussed under arbitrary material combinations. Also, it was found that the bonded strength of butt
joint can be evaluated in terms of the singular stress in good accuracy. In this study, the intensity of singular stress for bonded pipe is newly discussed in comparison with the one of bonded plate. The finite element method is applied to calculate the intensity of singular stress with varying the material combination
systematically. This method focuses on the result of first node, which locates on the end of the interface.
Since few studies are available for bonded pipe, in this study, first, the singular stress field at the end of the interface of the bonded pipe is investigated under several boundary conditions. Next, the effect of the material combination on the intensity of singular stress is discussed. This investigation may contribute to a better understanding of the debonding strength and initial interfacial cracks of bonded pipe
Metallization of double-stranded DNA triggered by bound galactose-modified naphthalene diimide
Get PDFNaphthalene diimide (NDI) derivatives bearing galactose moieties through different spacers, NDI-DS1 and NDI-DS2, were synthesized by the click reaction of the acetylene derivatives of NDI with galactose azide. They bound to double-stranded DNA with threading intercalation, as confirmed by the topoisomerase I assay and circular dichroism spectroscopy. The binding affinities of these ligands were on the order of 105 M–1 with several-fold higher affinity for double-stranded DNA than for single-stranded DNA. The silver mirror reaction on the double-stranded DNA bound to these ligands afforded silver nanowires that were converted to gold nanowires. In the atomic force microscopy measurements, the increased height of DNA areas on a mica plate was observed in the case of double-stranded DNA after NDI-DS2 treatment and subsequently silver mirror reaction, whereas the increased height of DNA areas was not observed in the case of single-stranded DNA after the same treatment
“Design for EMI Suppression” During Reverse Recovery by 600V Lateral SOI PiN Diode with Traps
Get PDF2014 International Conference on Solid State Devices and Materials, September 8, 2014, Tsukuba International Congress Center, Ibaraki, JapanPiN diode design for oscillation-induced EMI suppression is proposed with novel structure. The proposed diode is lateral structure with traps using SOI substrate. Conventional PiN diode with vertical structure generates waveform oscillation and the oscillation lower power electronics system reliability. The design of proposed lateral structure with traps will contributes the performance improvement of all of bipolar power devices including IGBT
Study on Image Quality Improvement Methods for Underwater Imaging Systems
Get PDF九州工業大学博士学位論文（要旨） 学位記番号:工博甲第367号 学位授与年月日:平成26年3月25
