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No full textDepartment of Materials Science and Engineeringclos
Study on a New Family Prussian Blue Analogues for Solid-State Batteries
No full textSchool of Energy and Chemical Engineering (Energy Engineering (Battery Science and Technology))clos
Development of Nodal Diffusion Code for VVER and HTGR analysis with Advanced Semi Analytic Nodal Method
No full textDepartment of Nuclear EngineeringThis paper presents the development and application of advanced semi-analytic nodal methods and practical nodal diffusion code for hexagonal geometry reactors, with a specific focus on VVER (Pressurized Water Reactor) and HTGR (High-Temperature Gas-Cooled Reactor). The aim is to improve the accuracy and computational efficiency of reactor analysis, enabling a wide range of analysis schemes and addressing the challenges posed by complex geometries and analysis of the diverse physical processes.
The proposed advanced semi-analytic nodal method (A-SANM) combines the advantages of the triangular node-based polynomial expansion nodal method (TPEN) and the source expansion nodal method (SENM) to achieve enhanced accuracy in neutron flux distribution and power profile calculations. The A-SANM is implemented as the main solver in the RAST-K VVER (RAST-V) nodal code, providing an efficient and accurate analysis tool for hexagonal geometry reactors.
The RAST-V code is further developed to incorporate various analysis schemes, including multi-cycle operation, thermal-hydraulic analysis, critical boron concentration search calculation, transient analysis, pin power reconstruction, spent nuclear fuel (SNF) analysis, and uncertainty quantification (UQ) analysis. These modules cover a wide range of applications, from long-term reactor operation planning to safety analysis and fuel performance evaluation.
The performance of the developed modules is evaluated using benchmark problems, including X2, Rostov-II, AER-DYN-001, AER-DYN-002, Kalinin-3, MHTGR-350, Novovoronezh-4, CB6, and Kozloduy-6. The results demonstrate that the A-SANM in RAST-V provides high accuracy, achieving close agreement with reference solutions, Monte Carlo simulations, and experimental data. Comparisons with other nodal methods and code systems further validate the superior performance of the A-SANM.
As the end of the operational license approaches for VVER-440 reactors, the analysis of end-of-cycle behavior becomes crucial. The SNF analysis module in RAST-V is specifically developed to address this demand. It utilizes Lagrange interpolation with power correction factors derived from the Bateman equation, allowing efficient and reliable analysis of spent nuclear fuel considering 3D core simulation conditions, such as boron concentration, fuel temperature, and moderator temperature. Comparative analyses on X2 cycles demonstrate the significant computational time savings of RAST-V compared to STREAM-SNF, while maintaining accuracy.
Uncertainty quantification is a vital component of reactor analysis. In this paper, a stochastic sampling method and principal component analysis (PCA) technique are implemented in STREAM for UQ analysis. These methods provide efficient calculations and reliable results, enabling the assessment of input parameter uncertainties and estimation of reactor response uncertainties.
In conclusion, this paper successfully demonstrates the development and application of advanced semi-analytic nodal methods and practical nodal diffusion codes for hexagonal geometry reactors. The proposed A-SANM improves accuracy and computational efficiency, and the developed modules in RAST-V provide essential tools for reactor analysis, enabling more accurate and efficient evaluations of reactor performance, safety, and fuel behavior.clos
Event-based Optical Flow Estimation via Multi-layer Representation
Get PDFGraduate School of Artificial IntelligenceOptical flow estimation plays a crucial role in computer vision applications, but it faces challenges in handling factors such as changes in lighting conditions, which adversely affect its accuracy. In recent years, event cameras have emerged as promising sensors for optical flow estimation in challenging scenarios due to their high temporal resolution and ability to capture pixel-level brightness changes. However, event-based optical flow estimation still encounters limitations related to the sparse nature of event data.
To address these limitations, this study proposes a multi-layer representation method for optical flow estimation. The multi-layer representation method divides the input data into multiple layers and estimates pixel-wise motion in each layer, enabling a clearer depiction of object motion trajectories and velocity variations. Additionally, object detection is incorporated as an auxiliary task to enhance motion estimation by focusing on event data around objects and leveraging boundary information.
By leveraging the advantages of event cameras and the multi-layer representation method, this re- search aims to enhance event-based optical flow estimation. Experimental results demonstrate the effec- tiveness of the proposed approach in achieving more accurate and detailed optical flow estimation.clos
Heavy-tailed Linear Bandit with Huber Regression
No full textGraduate School of Artificial Intelligenceclos
Barriers to the adoption of new technologies in rural areas: The case of unmanned aerial vehicles for precision agriculture in India
No full textTechnological advances can significantly transform agrarian rural areas by increasing productivity and efficiency while reducing labour intensive processes. For instance, the usage of Unmanned Aerial Vehicles (UAVs) can offer flexibility collecting real-time information of the crops enabling farmers to take timely decisions. However, little is known about the barriers to the adoption of such technologies by rural farmers in emerging economies like India. Building on an extensive literature review, focussed group discussions, and field visits, the barriers impacting the adoption are identified and classified into technical, social, behavioural, operational, economic, and implementation categories. The relevance of each barrier and its importance is evaluated using a hybrid multi-criteria framework built on the theory of Fuzzy Delphi and Fuzzy Analytical Hierarchy Process to identify the most crucial barriers to the adoption of UAVs to implement precision agriculture in rural India. The paper suggests new avenues for accelerating technology adoption in rural areas of emerging economies
A disease-associated XPA allele interferes with TFIIH binding and primarily affects transcription-coupled nucleotide excision repair
No full textXPA is a central scaffold protein that coordinates the assembly of repair complexes in the global genome (GG-NER) and transcription-coupled nucleotide excision repair (TC-NER) subpathways. Inactivating mutations in XPA cause xeroderma pigmentosum (XP), which is characterized by extreme UV sensitivity and a highly elevated skin cancer risk. Here, we describe two Dutch siblings in their late forties carrying a homozygous H244R substitution in the C-terminus of XPA. They present with mild cutaneous manifestations of XP without skin cancer but suffer from marked neurological features, including cerebellar ataxia. We show that the mutant XPA protein has a severely weakened interaction with the transcription factor IIH (TFIIH) complex leading to an impaired association of the mutant XPA and the downstream endonuclease ERCC1-XPF with NER complexes. Despite these defects, the patient-derived fibroblasts and reconstituted knockout cells carrying the XPAH244R substitution show intermediate UV sensitivity and considerable levels of residual GG-NER (???50%), in line with the intrinsic properties and activities of the purified protein. By contrast, XPA-H244R cells are exquisitely sensitive to transcription- blocking DNA damage, show no detectable recovery of transcription after UV irradiation, and display a severe deficiency in TC-NER-associated unscheduled DNA synthesis. Our characterization of a new case of XPA deficiency that interferes with TFIIH binding and primarily affects the transcription-coupled subpathway of nucleotide excision repair, provides an explanation of the dominant neurological features in these patients, and reveals a specific role for the C-terminus of XPA in TC-NER
T factor promotes non-alcoholic fatty liver disease by suppressing AMPK-mediated autophagy
No full textRole of Charge-Carrier Dynamics Toward the Fabrication of Efficient Air-Processed Organic Solar Cells
No full textOver the past couple of decades, immense research has been carried out to understand the photo-physics of an organic solar cell (OSC) that is important to enhance its efficiency and stability. Since OSCs undergoes complex photophysical phenomenon, studying these factors has led to designing new materials and implementing new strategies to improve efficiency in OSCs. In this regard, the invention of the non-fullerene acceptorshas greatly revolutionized the understanding of the fundamental processes occurring in OSCs. However, such vital fundamental research from device physics perspectives is carried out on glovebox (GB) processed OSCs and there is a scarcity of research on air-processed (AP) OSCs. This review will focus on charge carrier dynamics such as exciton diffusion, exciton dissociation, charge-transfer states, significance of highest occupied molecular orbital-offsets, and hole-transfer efficiencies of GB-OSCs and compare them with the available data from the AP-OSCs. Finally, key requirements for the fabrication of efficient AP-OSCs will be presented from a charge-carrier dynamics perspective. The key aspects from the charge-carrier dynamics view to fabricate efficient OSCs either from GB or air are provided