One way of harnessing and storing our most abundant and renewable energy source, sunlight, is by utilizing it to split water for the hydrogen generation as a storable form of fuel. Si, the most investigated material for solar-to-hydrogen technology has great potential as the single photoelectrode. While some success has been achieved in Si-Based photoelectrochemical (PEC) systems, they suffer from low efficiency and short longevity. Moreover, in order for hydrogen to be commercially viable, the existing challenges of electrical, optical, and catalysis management must be addressed concurrently. Herein, we work on the simultaneous improvement in light harvesting, charge carrier separation/transfer, and catalysis management of Si-based photocathodes, achieving best-in-class efficiency with stable electrochemical performance. By decoupling the light harvesting side from the electrocatalytic surface we nullify parasitic light absorption. We developed a Si bifacial (SiBF) PEC photocathode to absorb light on both sides of PEC devices, which exhibits a current density of 39.01 mA/cm2. Unlike conventional monofacial PEC cells, our bifacial design demonstrates excellent omnidirectional light harvesting capability. Furthermore, back buried junction photoelectrochemical (BBJ-PEC) cells were fabricated that can realize efficient decoupling of photon. This scheme enables maximum light-harvesting without any metal contact, which prevents the shadow effect during the water splitting reaction. The highest hydrogen evolution current density (41.76 mA/cm2) was demonstrated based on a single BBJ-PEC device. Additionally, wireless water splitting can be achieved when three BBJ-PEC cells were connected in series. The efficient PEC cell design described herein demonstrates promising performance, taking us a step closer to real-world solar-to-hydrogen production.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20582号 / 工博第4362号 / 新制||工||1678(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 陰山 洋, 教授 安部 武志 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21119号 / 工博第4483号 / 新制||工||1697(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 安部 武志, 教授 陰山 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21775号 / 工博第4592号 / 新制||工||1715(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 作花 哲夫, 教授 安部 武志 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Modern hybrid electric and pure electric vehicles are highly dependent on control algorithms to provide seamless safe and reliable operation under any driving condition, regardless of driver behavior. Three unique and independently operating supervisory control algorithms are introduced to improve reliability and vehicle performance on a series-hybrid electric vehicle with an all-wheel drive all-electric drivetrain. All three algorithms dynamically control or limit the amount of torque that can be delivered to the wheels through an all-electric drivetrain, consisting of two independently controlled brushless-direct current (BLDC) electric machines. Each algorithm was developed and validated following a standard iterative engineering development process which places a heavy emphasis on modeling and simulation to validate the algorithms before they are tested on the physical system. A comparison of simulated and in-vehicle test results is presented, emphasizing the importance of modeling and simulation in the design process.

No description available.

A Hessenberg variety is a subvariety of the flag variety parametrized by two maps: a Hessenberg function on $[n]$ and a linear map on $\C^n$. We study regular nilpotent Hessenberg varieties in Lie type A by focusing on the Hessenberg function $h=(n-1,n,\ldots,n)$. We first state a formula for the $f^w_{n,1}$ which generates the local defining ideal $J_{w,h}$ for any $w\in\Ss_n$. Second, we prove that there exists a convenient monomial order so that $\lead(J_{w,h})$ is squarefree. As a consequence, we conclude that each codimension-1 regular nilpotent Hessenberg variety is locally Frobenius split (in positive characteristic). / Thesis / Master of Science (MSc)

No description available.

No description available.

No description available.