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Biodegradable Mg–Mo2C MXene Air Batteries for Transient Energy Storage
Get PDFPrimary batteries are the fundamental power sources in small electronic gadgets and bio/ecoresorbable batteries. They are fabricated from benign and biodegradable materials and are of interest in environmental sensing and implants because of their low toxicity toward the environment and human body during decomposition. However, current bio/ecoresorbable batteries suffer from low operating voltages and output powers because of the occurrence of undesired hydrogen evolution reactions (HERs) at cathodes. Herein, Mo2C MXene was used as a cathode to achieve high operating voltage and areal power. Mo2C provides energy barriers for HERs in alkaline solutions, and such barriers suppress HERs and allow the oxygen reduction reaction to dominate at the cathode. The fabricated battery exhibits an operating voltage and areal power of 1.4 V and 0.92 mW cm–2, respectively. Degradation tests show that the full cell completely degrades within 123 days, leaving only Mo fragments from the electrode and biodegradable encapsulation. This study provides insights into bio/ecoresorbable batteries with high power and operating voltage, which can be used for environmental sensing.journal articl
Layer-Wise External Attention by Well-Localized Attention Map for Efficient Deep Anomaly Detection
Get PDFThe external attention mechanism offers a promising approach to enhance image anomaly detection (Hayakawa et al., in: IMPROVE, pp. 100-–110, 2023). Nevertheless, the effectiveness of this method is contingent upon the judicious selection of an intermediate layer with external attention. In this study, we performed a comprehensive series of experiments to clarify the mechanisms through which external attention improves detection performance. We assessed the performance of the LEA-Net (Hayakawa et al., in: IMPROVE, pp. 100–110, 2023), which implements layer-wise external attention, using MVTec AD and Plant Village datasets. The detection performances of the LEA-Net were compared with that of the baseline model under different anomaly maps generated by three unsupervised approaches. In addition, we investigated the relationship between the detection performance of LEA-Net and the selection of an attention point, which means an intermediate layer where external attention is applied. The findings reveal that the synergy between the dataset and the generated anomaly map influenced the effectiveness of the LEA-Net. For poorly localized anomaly maps, the selection of the attention point becomes a pivotal factor in determining detection efficiency. At shallow attention points, a well-localized attention map successfully notably improves the detection performance. For deeper attention points, the overall intensity of the attention map is essential; this intensity can be substantially amplified by layer-wise external attention, even for a low-intensity anomaly map. Overall, the results suggest that for layer-wise external attention, the positional attributes of anomalies hold greater significance than the overall intensity or visual appearance of the anomaly map.journal articl
Application of a Hippocampus-inspired Model toward Episodic Memory-based Navigation for Autonomous Mobile Robots
Get PDF5th International Symposium on Neuromorphic AI Hardware, March 1-2, 2024, Kyushu Institute of Technologyconference pape
Optimization of HTSC DC and AC cables taking into account the effect of the longitudinal magnetic field
Get PDFIt is known that in magnetic fields parallel to the transport current, an increase of the critical current is observed in most low-temperature and high-temperature superconductors — the effect of a longitudinal magnetic field (LMFE). LMFE has been theoretically predicted and experimentally confirmed in many studies. This article presents various methods for optimizing power coaxial cables based on high-temperature superconductors (HTS), considering LMFE. LMFE provides a higher current-carrying capacity of HTS DC cables and higher stability for HTS power AC cables, including lower AC losses. The results of optimization of HTS cables for both DC and AC applications with consideration of LMFE are presented and discussed. Two methods for calculating the magnetic field in coaxial HTS cables are presented: analytical and using the finite element method. The results of AC loss calculations and measurements for HTS cables are also presented.journal articl
需要予測のためのモンゴルの電力消費量の変化と特徴および温度依存性に関する研究
Get PDF九州工業大学九州工業大学博士学位論文（要旨）学位記番号: 工博甲第595号 学位授与年月日:令和6年9月25日thesi
竹由来リグニン：バイオマス由来グラフェン誘導体の作製とその機能性
Get PDF九州工業大学九州工業大学博士学位論文（要旨）学位記番号: 生工博甲第495号 学位授与年月日:令和6年9月25日thesi
カンチレバー間を弾性体薄膜で連結した広帯域圧電型MEMS音響センサーの研究
Get PDF九州工業大学博士（情報工学）1 序論| 2 MEMS マイクロフォンの動作原理と設計| 3 圧電型MEMS マイクロフォンの開発| 4 カンチレバー間を弾性体薄膜で連結した広帯域圧電型MEMS 音響センサーの開発|5 結論九州工業大学博士学位論文 学位記番号:情工博甲第403号 学位授与年月日:令和6年9月25日令和6年度doctoral thesi
有機電子デバイスの性能を向上させるための半導体ポリマーの配向および界面工学に関する研究
Get PDF九州工業大学博士（学術）1 Introduction| 2 Role of Orientation in Organic Electronic Devices| 3 Role of Molecular Conformation in Organic Electronic Devices| 4 Role of Aggregation in Organic Electronic Devices| 5 General Conclusion and Future ProspectsSemiconducting polymers (SCPs) have gained huge scientific interests owing to their excellent optical, electrical, and mechanical properties making them a potential candidate for the practical realization of organic electronics. Overall performance of organic electronic devices is controlled by the nature of the SCPs, their thin-film morphology, and related interfaces. Charge transport in SCPs thin films is dictated by various phenomena like transport along π-conjugated backbone followed by intermolecular as well as inter-domain hopping. In the recent past, huge efforts have been directed to improve the crystallinity of SCP thin-films by chemical structure engineering, developing various thin-film fabrication techniques, imparting molecular orientation and post-processing of the thin films aiming towards enhancing the charge carrier transport. Existing issues of thin-film fabrications such as the use of toxic halogenated solvents, difficulty in multilayer film fabrication, and swift characterization of large area thin films are still the stumbling blocks towards the large area implementation of the OEDs.
The thesis "Investigation of orientation and interface engineering of semiconducting polymers to enhance the performance of organic electronic devices" investigates the profound impact of molecular conformation, orientation, aggregation, and crystallinity on the charge transport properties and device performance of organic field-effect transistors (OFETs), organic Schottky diodes (OSDs), and organic memristors.
Chapter 1 introduces the concept of solution-processable semiconductor polymers and discusses the significance of macromolecular conformation, orientation, aggregation, and crystallinity in semiconductor polymer films. It also provides an overview of three types of organic electronic devices: OFETs, OSDs, and organic memristors.
Chapter 2 delves into the influence of molecular conformation on charge transport properties and device performance. By employing two widely studied SCPs, RR-P3HT and PTB7, the chapter demonstrates how careful selection of deposition techniques can control and tailor the molecular conformation. The Floating Film Transfer Method (FTM) enabled the alignment of RR-P3HT in an edge-on conformation, favoring charge transport in OFETs and organic memristors. Conversely, spin-coated RR-P3HT exhibited a mixed edge-on/face-on conformation, beneficial for out-of-plane charge transport in OSDs. The chapter also investigates the charge transport mechanism within organic memristors, proposing a model involving the splitting of energy bands and resonant tunneling of electrons facilitated by Al-AlOx nanoclusters.
Chapter 3 explores the significance of SCP orientation in organic semiconductor thin films. By employing FTM and polarized absorption spectroscopy, the chapter reveals striking differences in optical and morphological properties, as well as charge transport characteristics, between regioregular (RR-P3HT) and non-regioregular (NR-P3HT) poly(3-hexylthiophene) thin films. The optical characterization unveils the influence of molecular orientation on absorption spectra, while atomic force microscopy (AFM) studies provide insights into surface morphology. The fabrication and characterization of OFETs based on these oriented thin films further elucidate the impact of molecular orientation on device performance, with NR-P3HT FTM films exhibiting significantly higher electrical anisotropy compared to RR-P3HT counterparts.
Chapter 4 investigates the role of molecular aggregation in organic electronic devices, focusing on the polymer DPPT-TT. The research establishes a strong correlation between the viscosity ratio of the polymer ink and the sub-phase fluid, and the resulting orientation of polymer chains within self-assembled thin films. The study reveals that the dipole moment of the conjugated polymer monomers plays a crucial role in determining their self-assembly behavior and ink viscosity, consequently influencing the orientation of polymer chains. The impact of aggregation-induced orientation on the electrical properties of thin films is explored through the fabrication and characterization of OFETs, demonstrating exceptional charge carrier mobilities and remarkable shelf-life stability when the channel is aligned parallel to the film spreading direction.
In summary, the thesis provides a comprehensive understanding of the intricate interplay between molecular conformation, orientation, aggregation, and crystallinity, and their profound impact on the optoelectronic properties and device performance of organic electronics. The insights gained from this research open up promising avenues for the development of logic circuits, neuromorphic devices, vertical CMOS circuits, and flexible/stretchable organic electronic devices by leveraging the unique properties of oriented and engineered semiconductor polymer films.九州工業大学博士学位論文 学位記番号:生工博甲第499号 学位授与年月日:令和6年9月25日令和6年度doctoral thesi
Quantitative Crowdedness Measure for Evaluation of Hazard Avoidance Smartphone Apps for Visually Impaired at Station Platform
Get PDFAccidents in which visually impaired persons falling off station platforms have occurred repeatedly. These accidents are often caused by misunderstandings, loss of direction, and other factors that prevent correct recognition of the actual surroundings. Although the installation of platform doors is crucial, it is more important that visually impaired individuals can navigate around their surroundings and avoid potential hazards. In our study, we are conducting research on the use of smartphones to support the safe walking of the visually impaired. The application uses a camera to scan the surroundings, identify various objects based on the acquired RGB images, and then alert the user when a dangerous situation is detected. In our previous study, we confirmed that the system can detect steps, stairs, bicycles, and other objects which is an effective method to detect dangerous situations. Currently, we are extending the application to specialize in preventing the accident of falling from station platforms. Due to the fact that the application decides dangerous scene based on images captured by digital cameras, the accuracy of the detection would be getting worser when target objects are hidden by human; in other words, the crowdedness of the area affects the detection ability. One of requirements to use this app safely is to make clear the detection ability of the app with varying the crowdedness. To do this, we need to quantitatively define the crowdedness. In this paper, two measures, a range-based measure and a weighted distance measure, classified as local density are employed as quantitative crowdedness measures. This paper reports the experimental results comparing the two crowdedness measures, and examines which is more effective for the purpose. We conducted this experiments using a human location measurement system that can track the location of people walking and obtain their coordinates. This crowdedness measure can be applicable to evaluation criteria for apps with the same purpose of our app.journal articl