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Department of Energy Engineering (Battery Science and Technology)Lithium???oxygen (Li???O2) batteries are receiving large attention as a promising energy storage system for electrically powered mobile devices from mobile phone to electric vehicles due to their high energy density. However, the practical utilization of Li???O2 batteries remain insufficient due to several drawbacks such as poor energy efficiency and cycle performance. Solid catalysts are suggested for reduced polarization of Li???O2 batteries, resulting in the improving energy efficiency. However, solid catalysts exhibit the limited performance of Li???O2 batteries due to the spatial limitation. The redox mediators as soluble catalysts has been introduced for not only improving energy efficiency, but also surmounting spatial constraint of solid catalysts for Li???O2 batteries. The redox mediators effectively decreases the polarization for oxygen evolution reactions (OER) in the Li???O2 batteries, leading to improving electrochemical performance. On the other hand, the reduced polarization by redox mediators gradually reverts to original high polarization over a certain number of cycles owing to a continuous loss of their catalytic activity as cycle number increasing. The shuttle effect for redox mediators has been considered to be associated with the degradation of Li???O2 batteries with redox mediators, however, the failure mechanism does not fully elucidate the increasing polarization and loss of capacity observed with Li???O2 batteries. In this dissertation, it is demonstrated that the Li???O2 cells involved redox mediator deteriorates due to low compatibility between redox mediator and cell components, such as electrolyte solvent and Li metal anode. The electrolyte solvents influence on the electrochemical reversibility and radical stability of redox mediator. It is demonstrated that the radical stability of redox mediator dominantly influence on the cycle performance of Li???O2 batteries with redox mediator, whereas the electrochemical reversibility of redox mediator is hardly related with that of Li???O2 batteries. Therefore, the appropriate solvent for the redox mediator promotes the stability of redox mediator radical, resulting in the enhanced performance of Li???O2 batteries. Furthermore, the side reaction of redox mediator aggravates the electrochemical performance of Li metal and exhausts the redox mediators simultaneously. This unexpected reaction arises even though protective layer on the Li surface, which consists of lithium oxides formed by the oxygen contained in the electrolytes, covers the surface of Li metal. However, the introducing of LiNO3 as a salt, which can act two roles, such as the fast protective layer generator and a capturer for the redox mediator radicals, alleviates the side reaction, resulting in the improved cycle performance of Li???O2 batteries. Therefore, the optimization of electrolyte and the protection of Li metal anode for redox mediator strongly influence on the improving performance of Li???O2 batteries with a redox mediator. To clarify the failure mechanism of Li???O2 batteries containing redox mediators, 10???methylphenothiazine (MPT) is selected as a model redox mediator.ope

Rapid and high-capacity MgO composites by salt-controllable precipitation for pre- combustion CO2 capture

Pre-combustion CO2 capture at intermediate temperatures can allow for more flexibility to control over CO2 emission in various industrial processes. For example, the pre-combustion capture can be applied for an Integrated Gasification Combined Cycle (IGCC) due to the use of relatively mild operating temperatures and accessible heat sources. Efficient materials for CO2 capture and H2 production in water gas shift reactor can contribute to improving the overall reliability and efficiency in IGCC process. As a first step, we presented triple salt-promoted MgO composites (NaNaLi salts) by a precipitation method to enhance sorption capacity, rate, and stability. In the conventional precipitation method, a filtration step makes control and reproductivity of the salt composition difficult owing to the unknown residual salts. In this study, we developed a synthesis procedure of precipitation method to control the composition of salts as well as improve physical properties. As-prepared MgO exhibited excellent sorption capacities of 73.0 wt.% at 325 °C in pure CO2 and high sorption rate within 10 min. Stability of composites were evaluated under various gas and time condition and were superior to those of the other MgO-based sorbents reported. With a wet gas mixture (29% CO2, 3% H2O, and balance N2) for sorption and CO2 regeneration, the working capacity stabilized after 20 cycles at 23 and 4.6 wt% for 60/15 min and 10/5 min cycles, respectively. The enhancement and reduction of working capacity along cycles were explained based on liquid phase sintering, i.e., rearrangement, solid-reprecipitation, and densification. However, too long sorption time in the capacity evaluation is not practical because a fixed bed or fluidized bed has a difficulty of temperature control and a large bed size to control high volumes of gases. Therefore, further development is required for an advanced sorbent with high sorption rate and capacity in practical utilization. Therefore, as a second step, a facile method for sorbent with rapid and high-capacity CO2 capture was developed by incorporating additional metal ioninto salt-promoted MgO sorbents using a coprecipitation. At the same fast cycle (10min/5min), the cyclic sorption capacity of 12 wt.% was observed from the developed MgO composite by using wet mixture sorption (29 vol.% CO2, vol.% H2O and N2 balance) and CO2 regeneration. Please click Additional Files below to see the full abstract

Echocardiographic View Classification with Integrated Out-of-Distribution Detection for Enhanced Automatic Echocardiographic Analysis

In the rapidly evolving field of automatic echocardiographic analysis and interpretation, automatic view classification is a critical yet challenging task, owing to the inherent complexity and variability of echocardiographic data. This study presents ECHOcardiography VIew Classification with Out-of-Distribution dEtection (ECHO-VICODE), a novel deep learning-based framework that effectively addresses this challenge by training to classify 31 classes, surpassing previous studies and demonstrating its capacity to handle a wide range of echocardiographic views. Furthermore, ECHO-VICODE incorporates an integrated out-of-distribution (OOD) detection function, leveraging the relative Mahalanobis distance to effectively identify 'near-OOD' instances commonly encountered in echocardiographic data. Through extensive experimentation, we demonstrated the outstanding performance of ECHO-VICODE in terms of view classification and OOD detection, significantly reducing the potential for errors in echocardiographic analyses. This pioneering study significantly advances the domain of automated echocardiography analysis and exhibits promising prospects for substantial applications in extensive clinical research and practice

血中のD-アミノ酸含有ペプチド及び蛋白質の分析に関する研究

京都大学0048新制・課程博士博士(理学)甲第22275号理博第4589号新制||理||1659(附属図書館)京都大学大学院理学研究科化学専攻(主査)講師 木野内 忠稔, 教授 杉山 弘, 教授 秋山 芳展学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDGA

Energy Management Strategy Based on V2X Communications and Road Information for a Connected PHEV and Its Evaluation Using an IDHIL Simulator

Conventional energy management strategies (EMSs) of hybrid electric vehicles (HEVs) only utilize in-vehicle information, such as an acceleration pedal, velocity, acceleration, engine RPM, state of charge (SOC), and radar. This paper presents a new EMS using out-vehicle information obtained by vehicle to everything (V2X) communication. The new EMS integrates cooperative eco-driving (CED) guidance and an adaptive equivalent consumption minimum strategy (A-ECMS) based on V2X communication information and road information. CED provides a guide signal and a guide speed to the driver. It guides pedal behavior in terms of coasting driving, acceleration and deceleration, and target speed. A-ECMSs calculate the target SOC based on the simplified road information of the planned route and reflects it in the equivalent factor. An integrated driving hardware-in-the-loop (IDHIL) simulator is also built to prove the new EMS by integrating a V2X communication device, a VANET simulator, and a vehicle simulator. The IDHIL test results demonstrate the validity and performance of the proposed EMS in a V2X communication environment

Converting to long stability

Rechargeable aqueous batteries are attractive energy storage technologies owing to their low cost and high safety, but suffer from poor electrochemical performance. Now, an aqueous mild-acid-based Zn/MnO2 battery that operates via a conversion mechanism is shown to have a long-term cycling stability

Integrating Driving Hardware-in-the-Loop Simulator with Large-Scale VANET Simulator for Evaluation of Cooperative Eco-Driving System

Recent advances in information and communication technology (ICT) have enabled interaction and cooperation between components of the transportation system, and cooperative eco-driving systems that apply ICT to eco-driving systems are receiving significant attention. A cooperative eco-driving system is a complex system that requires consideration of the electronic control unit (ECU) and vehicle-to-everything (V2X) communication. To evaluate these complex systems, it is needed to integrate simulators with expertise. Therefore, this study presents an integrated driving hardware-in-the-loop (IDHIL) simulator for the testing and evaluation of cooperative eco-driving systems. The IDHIL simulator is implemented by integrating the driving hardware-in-the-loop simulator and a vehicular ad hoc network simulator to develop and evaluate a hybrid control unit and cooperative eco-driving application for the connected hybrid electric vehicle (CHEV). A cooperative eco-driving speed guidance application is utilized to demonstrate the use of our simulator. The results of the evaluation show the improved fuel efficiency of the CHEV through a calculation of the optimal speed profile and the optimal distribution of power based on V2X communication. Finally, this paper concludes with a description of future directions for the testing and evaluation of cooperative eco-driving systems

Cobalt-catalyzed Formation of Grignard Reagents via C‒O Bond Activation

11Nsciescopu

Extremely Low-Profile Monopolar Microstrip Antenna with Wide Bandwidth

In this paper, we propose a new monopolar microstrip antenna for a high-speed moving swarm sensor network. The proposed antenna shows an extremely thin substrate thickness supported with an omni-directional radiation pattern and wide operation frequency bandwidth. First, to achieve the low-profile monopolar microstrip antenna, the symmetrical center feeding network and the gap-coupled six arrayed patches which form a hexagonal microstrip radiator were utilized. The partially loaded ground-slots under the top patches were employed to improve the radiation performance and adjust the impedance bandwidth. Second, to obtain the broad bandwidth of the low-profile monopolar microstrip antenna, the degenerated non-fundamental TM02 modes, that is, even and odd TM02 modes, were carefully analyzed. To verify the feasibility of the degenerated TM02 mode operation, the parametric study of the proposed antenna was theoretically investigated and implemented with the optimized parameter dimensions. Finally, the fabricated antenna showed a 0.254 mm-thick substrate and demonstrates 1.5-wavelength resonant monopolar radiation with broad impedance bandwidth of 855 MHz and its factional bandwidth of 15.24% at the resonant frequency of 5.57 GHz

Electrochemically Generated KO2 as a Phase-Transfer Mediator for Na-O-2 Batteries

Superoxide-based Na-O-2 batteries have attracted much attention as promising alternatives to peroxide-based Li-O-2 batteries because of their small polarization for oxygen evolution reactions. However, the limited solubility of their discharge product, NaO2, leads to the surface-confined mechanism at high current densities, resulting in the poor energy density of Na-O-2 batteries. In this connection, a few protic phase-transfer catalysts, such as water and benzoic acid, have been examined to improve reversible capacity because they promote the solution-mediated mechanism. Herein, KO2, which is electrochemically generated from potassium trifluoromethanesulfonate dissolved in electrolytes during discharge, is introduced as a phase-transfer mediator for Na-O-2 batteries. The reaction mechanism of Na-O-2 batteries containing a KO2 mediator is clarified through ex situ XRD, cross-sectional SEM, and ICP analyses. KO2 plays the role of a phase-transfer mediator because the desolvation rate of KO2 is slower than that of NaO2. As a result, Na-O-2 batteries with KO2 show the solution-mediated mechanism rather than the surface-confined mechanism, thus delivering a high reversible capacity of approximately 6 mAh cm(-2). In addition, since KO2 is chemically and electrochemically more stable than previous protic phase-transfer mediators, Na-O-2 cells with KO2 show stable cycle performance, such as negligible capacity fading over 25 cycles