High-harmonic generation in the Rice-Mele model: Role of intraband current originating from interband transition

We consider high-harmonic generation (HHG) in the Rice-Mele model to study the role of the intraband current originating from the change of the intraband dipole via interband transition. This contribution, which has been often neglected in previous works, is necessary for the consistent theoretical formulation of the light-matter coupling. We demonstrate that the contribution becomes crucial when the gap is smaller than or comparable to the excitation frequency and the system is close to the half filling.Comment: 6 pages, 2 figure

Life cycle management of concrete structures based on sustainability indicators

A concrete structure should be sufficiently planned, designed, executed and maintained to ensure its requirements during the life cycle. However, structures suffering from serious deterioration in structural members and sometimes subsequent loss in sustainability have been often found due to various reasons. One of the reasons is lack of total management for the structure. To meet these facts, it is extremely important to pursue coordination of engineering work in the design, execution and maintenance stages. The life cycle management is an organized system to support engineers decision to realize sufficient sustainability of the structure in the design, execution, maintenance, and all related work during its life cycle. The life cycle management is implemented based according to the life cycle management scenario in which balance of several sustainability indicators should be considered with ensuring overall sustainability. The sustainability indicators will be determined from the social, environmental and economic points of view. The scenario should be regularly reviewed based on the PDCA cycle and be updated if necessary. This paper deals with the concept and framework of the life cycle management of concrete structures to ensure sustainability during the structural life

Crack Detection on Concrete Surfaces Using Deep Encoder-Decoder Convolutional Neural Network: A Comparison Study Between U-Net and DeepLabV3+

Maintenance of infrastructures is a crucial activity to ensure safety using crack detection methods on concrete structures. However, most practice of crack detection is carried out manually, which is unsafe, highly subjective, and time-consuming. Therefore, a more accurate and efficient system needs to be implemented using artificial intelligence. Convolutional neural network (CNN), a subset of artificial intelligence, is used to detect cracks on concrete surfaces through semantic image segmentation. The purpose of this research is to compare the effectiveness of cutting-edge encoder-decoder architectures in detecting cracks on concrete surfaces using U-Net and DeepLabV3+ architectures with potential in biomedical, and sparse multiscale image segmentations, respectively. Neural networks were trained using cloud computing with a high-performance Graphics Processing Unit NVIDIA Tesla V100 and 27.4 GB of RAM. This study used internal and external data. Internal data consisted of simple cracks and were used as the training and validation data. Meanwhile, external data consisted of more complex cracks, which were used for further testing. Both architectures were compared based on four evaluation metrics in terms of accuracy, F1, precision, and recall. U-Net achieved segmentation accuracy = 96.57%, F1 = 87.55%, precision = 88.15%, and recall = 88.94%, while DeepLabV3+ achieved segmentation accuracy = 96.47%, F1 = 85.29%, precision = 92.07%, and recall = 81.84%. Experiment results (internal and external data) indicated that both architectures were accurate and effective in segmenting cracks. Additionally, U-Net and DeepLabV3+ exceeded the performance of previously tested architecture, namely FCN

Internal Knowledge Sharing by Infrastructure Maintenance Engineers in Small and Medium Size Construction Companies in Japan

It is necessary to increase the capability of engineers to carry out maintenance management for keeping infrastructure safe and serviceable. Many regional training programs have been established to develop engineers into “maintenance experts.” While small and medium size construction companies and engineering consultants play an active role in infrastructure maintenance, they have limited human and economic resources for joining the training programs, so the sharing of knowledge acquired from the programs becomes important for improving the capability of the company as a whole. The objective of this research is to investigate how engineers who participated in regional training programs shared their knowledge inside their organization using an online questionnaire survey. It was found that leadership is an important factor for driving knowledge sharing activities, particularly for adapting the knowledge acquired from the training program to the company’s environment. However, the lack of experience serves as a barrier to the deeper transfer of knowledge, such as on-the-job training or seminars, as these methods of knowledge sharing require expert knowledge. For organizations to improve their knowledge sharing practices, it is necessary to consider the type of knowledge to be shared and the appropriate method for sharing, along with the improvement of the leadership for knowledge sharing in the organization

High harmonic spin-orbit angular momentum generation in crystalline solids preserving multiscale dynamical symmetry

Symmetries essentially provide conservation rules in nonlinear light-matter interactions, that facilitate control and understanding of photon conversion processes or electron dynamics. Since anisotropic solids have rich symmetries, they are strong candidate to control both optical micro- and macroscale structures, namely spin (circular polarization) and orbital angular momentum (spiral wavefront), respectively. Here, we show structured high harmonic generation linked to the anisotropic symmetry of a solid. By strategically preserving a dynamical symmetry arising from the spin-orbit interaction of light, we generate multiple orbital angular momentum states in high-order harmonics. The experimental results exhibit the total angular momentum conservation rule of light even in the extreme nonlinear region, which is evidence that the mechanism originates from a dynamical symmetry. Our study provides a deeper understanding of multiscale nonlinear optical phenomena and a general guideline for using electronic structure to control structured light, such as through Floquet engineering

Diabatic and adiabatic transitions between Floquet states imprinted in coherent exciton emission in monolayer WSe₂

光を着た電子状態の飛び移りを世界で初めて観測に成功 --赤外光パルスによる電子状態制御へ--. 京都大学プレスリリース. 2022-12-28.Floquet engineering is a promising way of controlling quantum system with photon-dressed states on an ultrafast time scale. So far, the energy structure of Floquet states in solids has been intensively investigated. However, the dynamical aspects of the photon-dressed states under ultrashort pulse have not been explored yet. Their dynamics become highly sensitive to the driving field transients, and thus, understanding them is crucial for ultrafast manipulation of a quantum state. Here, we observed the coherent exciton emission in monolayer WSe₂ at room temperature at the appropriate photon energy and the field strength of the driving light pulse using high-harmonic spectroscopy. Together with numerical calculations, our measurements revealed that the coherent exciton emission spectrum reflects the diabatic and adiabatic dynamics of Floquet states of excitons. Our results provide a previosuly unexplored approach to Floquet engineering and lead to control of quantum materials through pulse shaping of the driving field

Dynamical symmetry of strongly light-driven electronic system in crystalline solids

The Floquet state, which is a periodically and intensely light driven quantum state in solids, has been attracting attention as a novel state that is coherently controllable on an ultrafast time scale. An important issue has been to demonstrate experimentally novel electronic properties in the Floquet state. One technique to demonstrate them is the light scattering spectroscopy, which offers an important clue to clarifying the symmetries and energy structures of the states through symmetry analysis of the polarization selection rules. Here, we determine circular and linear polarization selection rules of light scattering in a mid-infrared-driven Floquet system in monolayer MoS2 and provide a comprehensive understanding in terms of the "dynamical symmetry" of the Floquet state