オペランドX線吸収分光法による固体高分子型燃料電池における酸素還元反応用のPt系触媒の研究

京都大学新制・課程博士博士(人間・環境学)甲第25386号人博第1128号京都大学大学院人間・環境学研究科相関環境学専攻(主査)教授 内本 喜晴, 教授 藤田 健一, 教授 高木 紀明, 教授 竹口 竜弥学位規則第4条第1項該当Doctor of Human and Environmental StudiesKyoto UniversityDFA

Response of Rotor Blade Flapping in Forward Flight

The article aims to determine the effect of reverse flow on the damping, frequency, and the stability boundaries of helicopter rotor-blade flapping dynamics and to investigate the behavior of the system in the limit of small Lock number and small advance ratio. The system is represented by a linear ordinary differential equation that gives results resembling to experimental data

Simulation of the Spin Field Effect Transistors: Effects of Tunneling and Spin Relaxation on its Performance

A numerical simulation of spin-dependent quantum transport for a spin field effect transistor (spinFET) is implemented in a widely used simulator nanoMOS. This method includes the effect of both spin relaxation in the channel and the tunneling barrier between the source/drain and the channel. Account for these factors permits setting more realistic performance limits for the transistor, especially the magnetoresistance, which is found to be lower compared to earlier predictions. The interplay between tunneling and spin relaxation is elucidated by numerical simulation. Insertion of the tunneling barrier leads to an increased magnetoresistance. Numerical simulations are used to explore the tunneling barrier design issues.Comment: 31 pages, 14 figures, submitted to Journal of Applied Physic

Passive detection of moving aerial target based on multiple collaborative GPS satellites

Passive localization is an important part of intelligent surveillance in security and emergency applications. Nowadays, Global Navigation Satellite Systems (GNSSs) have been widely deployed. As a result, the satellite signal receiver may receive multiple GPS signals simultaneously, incurring echo signal detection failure. Therefore, in this paper, a passive method leveraging signals from multiple GPS satellites is proposed for moving aerial target detection. In passive detection, the first challenge is the interference caused by multiple GPS signals transmitted upon the same spectrum resources. To address this issue, successive interference cancellation (SIC) is utilized to separate and reconstruct multiple GPS signals on the reference channel. Moreover, on the monitoring channel, direct wave and multi-path interference are eliminated by extensive cancellation algorithm (ECA). After interference from multiple GPS signals is suppressed, the cycle cross ambiguity function (CCAF) of the signal on the monitoring channel is calculated and coordinate transformation method is adopted to map multiple groups of different time delay-Doppler spectrum into the distance−velocity spectrum. The detection statistics are calculated by the superposition of multiple groups of distance-velocity spectrum. Finally, the echo signal is detected based on a properly defined adaptive detection threshold. Simulation results demonstrate the effectiveness of our proposed method. They show that the detection probability of our proposed method can reach 99%, when the echo signal signal-to-noise ratio (SNR) is only −64 dB. Moreover, our proposed method can achieve 5 dB improvement over the detection method using a single GPS satellite

Using heterogeneous satellites for passive detection of moving aerial target

Passive detection of a moving aerial target is critical for intelligent surveillance. Its implementation can use signals transmitted from satellites. Nowadays, various types of satellites co-exist which can be used for passive detection. As a result, a satellite signal receiver may receive signals from multiple heterogeneous satellites, causing difficult in echo signal detection. In this paper, a passive moving aerial target detection method leveraging signals from multiple heterogeneous satellites is proposed. In the proposed method, a plurality of direct wave signals is separated in a reference channel first. Then, an adaptive filter with normalized least-mean-square (NLMS) is adopted to suppress direct-path interference (DPI) and multi-path interference (MPI) in a surveillance channel. Next, the maximum values of the cross ambiguity function (CAF) and the fourth order cyclic cumulants cross ambiguity function (FOCCCAF) correspond into each separated direct wave signal and echo signal will be utilized as the detection statistic of each distributed sensor. Finally, final detection probabilities are calculated by decision fusion based on results from distributed sensors. To evaluate the performance of the proposed method, extensive simulation studies are conducted. The corresponding simulation results show that the proposed fusion detection method can significantly improve the reliability of moving aerial target detection using multiple heterogeneous satellites. Moveover, we also show that the proposed detection method is able to significantly improve the detection performance by using multiple collaborative heterogeneous satellites

A New Method Applied to the Quadrilateral Membrane Element with Vertex Rigid Rotational Freedom

In order to improve the performance of the membrane element with vertex rigid rotational freedom, a new method to establish the local Cartesian coordinate system and calculate the derivatives of the shape functions with respect to the local coordinates is introduced in this paper. The membrane elements with vertex rigid rotational freedom such as GQ12 and GQ12M based on this new method can achieve higher precision results than traditional methods. The numerical results demonstrate that the elements GQ12 and GQ12M with this new method can provide better membrane elements for flat shell elements. Furthermore, this new method presented in this paper offers a new approach for other membrane elements used in flat shell element to improve the computing accuracy

Performance of passive UHF RFID in cascaded correlated generalized Rician fading

Ultra high frequency radio frequency identification (UHF RFID) systems can use passive tags to reflect the signal from the reader’s transmitting antenna back to the reader’s receiving antenna for information delivery. This gives a cascaded channel that is a product of two fading components. In this work, the probability of detection, defined as the probability that the received power is above the receiver sensitivity, is derived when the two fading components suffer from correlated generalized Rician fading. This includes the Rayleigh, Rician and Nakagamim channels in the literature as special cases. Numerical results are presented to show the effects of link distances, receiver sensitivities and channel parameters on the detection probability

Sociological Reflection on Cause of Multipartite Mediation Mechanism

Relative to traditional mediation system, multipartite mediation mechanism refers to a kind of resolving system based on the situation that social conflicts and social disputes wide spread in our country. From the view of sociology, this article analyzes multipartite mediation mechanism, which has great significance to realize cause of multipartite mediation mechanism, perfect multipartite mediation mechanism further and pursue social harmony process

Wireless powered communication networks using peer harvesting

For an energy-constrained wireless network, energy harvesting (EH) is a promising technology to prolong the network life. Whether traditional near-field wireless power transfer (WPT) using inductive and resonant coupling or far-field WPT via radiated electromagnetic waves, both of them draw considerable research interests these years [1], [2]. In particular, the far-field WPT is meaningful for wireless powered communication (WPC) networks. A fundamental tradeoff was first studied for simultaneous wireless information and power transfer (SWIPT) in [3], [4]. These results aroused the interest of researchers. Subsequently, wireless communication with EH technology was presented in [5], [6]