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Origin of nonlinear photocurrents in chiral multifold semimetal CoSi unveiled by terahertz emission spectroscopy

Physical Review B 2024年第20期110卷 L201118-L201118页

作者： Yao-Jui Chan Syed Mohammed Faizanuddin Raju Kalaivanan Sankar Raman Hsin Lin Uddipta Kar Akhilesh Kr. Singh Wei-Li Lee Ranganayakulu K. Vankayala Institute of Physics Academia Sinica Taipei 11529 Taiwan Taiwan International Graduate Program Academia Sinica Taipei 11529 Taiwan Department of Engineering and System Science National Tsing Hua University Hsinchu 300044 Taiwan

Spectroscopic identification of distinct nonlinear photocurrents unveils quantum geometric properties of electron wave functions and the momentum-space topological structures. This is especially interesting, but still puzzling, for chiral topological semimetals with possibilities of hosting giant quantized circular photogalvanic effect. Here we report a comprehensive terahertz (THz) emission spectroscopic analysis of nonlinear photoconductivity of chiral multifold CoSi at 0.26 ∼ 1 eV. We find a large linear shift conductivity (17µA/V2), and confirm a giant injection conductivity (167µA/V2) as a consequence of strongly interfered nonquantized contributions from the vicinity of multifold nodes with opposite chiralities. The bulk injection current excited by the pump field with a complex wave vector is shown to carry both longitudinal and transverse components. Symmetry analyses further unveil weak nonlocal photon drag effect in addition to the photogalvanic effect. This work not only highlights chiral transition-metal monosilicides for midinfrared photovoltaic applications via various nonlinear optical channels, but also consolidates the THz spectroscopy for quantitative photovoltaic research.

关键词： Optical & microwave phenomena Photocurrent Topological materials Weyl semimetal Resistivity measurements Terahertz techniques

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Potato Leaf Disease Detection by Means of Vision Transformer and CoAtNet Architecture

Potato Leaf Disease Detection by Means of Vision Transformer...

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International Conference on Technology, Informatics, Management, engineering, and Environment (TIME-E)

作者： Mesa Anugerah Kenan Sergio Ariel Brandon Stevano Siallagan Endra Joelianto Engineering Physics Study Program Institut Teknologi Bandung Bandung Indonesia Instrumentation Control and Automation Research Group Institut Teknologi Bandung Bandung Indonesia

ISBN: (数字)9798350364750

ISBN: (纸本)9798350364767

Potatoes are a food source that is beneficial for humans in various aspects, such as having nutritional and economic value. However, potato plants are susceptible to many diseases. To address this issue, various researchers have suggested methods utilizing machine learning and image processing for automatic disease type detection. This paper introduces a disease detection model for potato leaf images, employing two computer vision techniques: Vision Transformer (ViT) and CoAtNet. The dataset used in this paper consisted of 30,760 augmented images divided into seven classes. The ViT model had a test accuracy of 99.32% and a validation accuracy of99.12%. Meanwhile, the CoAtNEt model had a test accuracy of 99.58 % and a validation accuracy of 99.48 %. These results show that both models can be used in the detection of potato leaf diseases.

关键词： Productivity Computer vision Accuracy Computational modeling Image processing Machine learning Transformers Informatics Monitoring Diseases

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Insights into Calculating Reference Discontinuity Factors with Serpent Monte Carlo Code

SSRN

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SSRN 2024年

作者： Fridman, Emil Smith, Jacob D. Kotlyar, Dan Dresden Germany Nuclear and Radiological Engineering and Medical Physics Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology AtlantaGA30332-0405 United States

This study explores the calculation of Reference Discontinuity Factors (RDFs) using Serpent, focusing on the methodology and potential pitfalls. In two-step reactor analyses, consistently generated RDFs are crucial for aligning homogeneous nodal diffusion results with the reference heterogeneous transport solution. However, the Serpent internal diffusion solver, based on the Analytic Function Expansion Nodal (AFEN) method, may not be compatible with other nodal methods such as NEM. Additionally, the solver can suffer from instabilities, particularly in multi-group calculations, leading to erroneous RDFs. Despite these challenges, Serpent can generate the necessary raw data for RDF calculation, which can be accurately processed using external diffusion solvers. Two numerical examples - a 1D fuel-reflector model and a 2D SMR core model - illustrate the effects of consistent and inconsistent RDFs on simulation accuracy. The study underscores the importance of using compatible diffusion solvers and thoroughly assessing RDFs to avoid errors in reactor simulations. © 2024, The Authors. All rights reserved.

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Automating RTGC with PID Control: Utilizing Camera-Based Image Processing and Object Detection

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IFAC-PapersOnLine 2024年第7期58卷 299-304页

作者： Steven Bandong Yul Y. Nazaruddin Augie Widyotriatmo Muhammad R. Miransyahputra Yan Setiaji Engineering Physics Doctoral Program Faculty of Industrial Technology Institut Teknologi Bandung Bandung Indonesia Instrumentation Control and Automation Research Group Faculty of Industrial Technology Institut Teknologi Bandung Bandung Indonesia

The high traffic in the container yard requires effective management, and one method to address this is through automation. The Rubber Tyred Gantry Crane (RTGC) plays a crucial role in container yards. Automating the RTGC involves determining the container’s location and sway angle to provide feedback for the control system. The advancements in computer vision technology offer a unique solution to tackle these challenges. This paper proposes image processing as a means to sense the sway angle and MobileNet SSD to detect the container’s location. The proposed method yields accurate measurement results and is integrated with optimized PID-PD for position and sway angle control in RTGC. The effectiveness of the proposed method is demonstrated through successful performance in both simulation and experiments conducted on a laboratory-scale RTGC prototype.

关键词： port automation RTGC control system computer vision optimization camera based sensor

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Atomistic observation of in situ fractured surfaces at a V-doped WC–Co interface

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Journal of Materials Science & Technology 2022年第15期110卷 103-108页

作者： Congying Xiang Min Shen Chongze Hu Lok Wing Wong Hongbo Nie Huasheng Lei Jian Luo Jiong Zhao Zhiyang Yu State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhou 350002China Department of NanoEngineering Program of Materials Science and EngineeringUniversity of California San DiegoLa JollaCA 92093United States Department of Applied Physics Hong Kong Polytechnic UniversityHong Kong 999077China School of Materials Science and Engineering Baise UniversityBaise 533000China

*** Cemented carbides are composites of WC ceramic phases and metallic Co binders that endow them with superior hardness and excellent *** metals are widely used as metal cutting and rock drilling tools[1,2].Their hardness is believed to be inversely proportional to the sizes of WC grains^([3]).Grain growth inhibitors are widely employed to achieve smaller grain sizes.

关键词： toughness grain sizes

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Evidence of magnetoelectronic electromagnon-mediated transport in flexoelectronic heterostructures

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Physical Review B 2023年第16期107卷 165305-165305页

作者： Anand Katailiha Paul C. Lou Ravindra G. Bhardwaj W. P. Beyermann Sandeep Kumar Department of Mechanical Engineering University of California Riverside California 92521 USA Department of Physics and Astronomy University of California Riverside California 92521 USA Materials Science and Engineering Program University of California Riverside California 92521 USA

The superposition of atomic vibrations and flexoelectronic effect gives rise to a cross correlation between free charge carriers and temporal magnetic moment of phonons in conducting heterostructures under an applied strain gradient. The resulting dynamical coupling is expected to give rise to quasiparticle excitations called magnetoelectronic electromagnons that carry electronic charge and temporal magnetic moment. Here, we report experimental evidence of magnetoelectronic electromagnons in the freestanding degenerately doped p-Si based heterostructure thin film samples. These quasiparticle excitations give rise to long-distance (>100 μm) spin transport, demonstrated using spatially modulated transverse magnetothermoelectric and nonlocal resistance measurements. The magnetoelectronic electromagnons are nonreciprocal and give rise to large magnetochiral anisotropy (0.352A−1T−1) that diminishes at lower temperatures. The superposition of nonreciprocal magnetoelectronic electromagnons gives rise to longitudinal and transverse modulations in charge carrier density, spin density, and magnetic moment, demonstrated using the Hall effect and edge dependent magnetoresistance measurements, which can also be called inhomogeneous magnetoelectronic multiferroic effect. These quasiparticle excitations are analogous to photons where time dependent polarization and temporal magnetic moment replace electric and magnetic field, respectively, and most likely topological because they manifest topological Nernst effect. Hence, the magnetoelectronic electromagnon can potentially give rise to quantum interference and entanglement effects in conducting solid state systems at room temperature in addition to efficient spin transport.

关键词： Flexoelectricity Magnetic coupling Magnetotransport Spin current Spin-phonon coupling Doped semiconductors Multiferroics

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Constrained and Unconstrained Nonlinear Control of Rubber Tyred Gantry Crane (RTGC) with DC Motor Using Sliding Mode Controller

Constrained and Unconstrained Nonlinear Control of Rubber Ty...

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International Conference on Control, Automation and Systems ( ICCAS)

作者： Cristian MP Napitupulu Steven Bandong Yul Yunazwin Nazaruddin Parsaulian I. Siregar Department of Engineering Physics Faculty of Industrial Technology Institut Teknologi Bandung Bandung Indonesia Engineering Physics Doctoral Program Faculty of Industrial Technology Institut Teknologi Bandung Bandung Indonesia Department of Engineering Physics Instrumentation and Control Research Group Institut Teknologi Bandung Bandung Indonesia

The increasing exchange of goods between countries and continents necessitates efficient transportation facilities, with cargo seaports playing a vital role. Within each cargo seaport, the Rubber Tyred Gantry Crane (RTGC) stands out as crucial heavy equipment that requires automation to manage heavy cargo traffic and eliminate bottlenecks. While linear control methods are commonly employed to address this challenge, the inherent nonlinear behavior of the system must be considered. This paper focuses on designing a nonlinear control method, specifically the Sliding Mode Controller (SMC), to create an effective MIMO controller for managing the position, cable length, and sway of the gantry crane system. Two DC motors serve as actuators for controlling the trolley position and cable length, which hoists the container. The nonlinear gantry crane model, integrated with the nonlinear DC motor model, is elaborately derived. Subsequently, the designed non-linear SMC control law and sliding surface are simulated to assess control performance. Acknowledging the limitation of the power source and DC motor specifications, the paper also explores control performance when the voltage to control R TGC is constrained within a specified range. The results demonstrate that the proposed method yields excellent control performance for both constrained and unconstrained control outputs.

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Polarization switching in ferroelectric HfO2 from first-principles lattice mode analysis

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Physical Review B 2025年第13期111卷 134106-134106页

作者： Yubo Qi Sobhit Singh Karin M. Rabe Department of Physics University of Alabama at Birmingham Birmingham Alabama 35294 USA Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Department of Physics and Astronomy Rutgers University Piscataway New Jersey 08854 USA

In this paper, we introduce a first-principles-based lattice mode analysis method to investigate the competition between different polarization switching paths in HfO2. Because the stability of the polar orthorhombic Pca21 phase of HfO2 arises from a trilinear coupling, polarization switching requires the flipping of not only the polar Γ15Z mode, but also at least one zone-boundary antipolar mode. This means that each polarization state has multiple variants, leading to multiple possible switching paths connecting up- and down-polarized states, which can be systemically enumerated within this framework for efficient identification of the optimal switching path. Our lattice mode analysis also explains why the activation energy of propagation of the most widely studied domain-wall structure in HfO2, which requires the reversal of the X2− mode, is much larger than that of propagation of domain-wall structures with a uniform sign for the X2− mode. This approach deepens our understanding of distinctive properties of ferroelectric HfO2 related to polarization switching and domain-wall motion, including sluggish domain-wall motion, robust ferroelectricity in thin films, and the observation that the antipolar Pbca phase can hardly be transformed to the ferroelectric Pca21 phase by an electric field. Our mode analysis method can be more generally applied to any improper or hybrid improper ferroelectric, in which polarization switching requires changes of nonpolar distortions, for systematic and efficient prediction of optimal switching paths and estimation of coercive fields.

关键词： Ferroelectricity

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Simulation of Cable-Driven Parallel Robot (CDPR) for Application in Creating Batik Patterns

Simulation of Cable-Driven Parallel Robot (CDPR) for Applica...

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International Conference on Instrumentation Control and Automation (ICA)

作者： Indah Radityo Putri Alfisena Juwandana Eko Mursito Budi Estiyanti Ekawati Komarudin Kudiya Instrumentation and Control Graduate Program Institut Teknologi Bandung Bandung Indonesia Departement of Engineering Physics Engineering Physics Research Group Institut Teknologi Bandung Bandung Indonesia Rumah Batik Komar Bandung Indonesia

The usage of the cable-driven parallel robot (CDPR) is proposed to create a batik pattern. In the proposed CDPR system, the artist can intervene in the pattern-making process to maintain pattern uniqueness. Therefore, to provide the system's flexibility and simplicity, CDPR with four cables will be used where all the cables only connect to the top of the end-effector. The design of four cables with four poles will give a simple structure, and the pole can be moved easily according to the cloth's size, usually in the shape of a rectangle. This flexible design allows the artist to intervene via software or manually push the end effector. In this paper, we explored the cable's length calculation, various path simulations to see system accuracy and flexibility, and the analysis of the CDPR workspace. From the CDPR simulation, we can conclude that the longest cable length needed is 1.22 meters, and the shortest is 0 due to the assumption of the pulley as a point. Implementing inverse kinematics in simulation shows that the end-effector can follow various paths, including straight line, square, circle, diagonal, two-circular, spiral, and planetary orbit. We also calculate the percentage of the area if the pulley has a minimal degree to the pole. With the assumption that the minimal degree is 5°, the %Area we got is 75.6%.

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Design and Implementation of Four Cables Suspended Cable-driven Parallel Robot for Pendulum Batik Machine

Design and Implementation of Four Cables Suspended Cable-dri...

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International Conference on Advanced Mechatronics, Intelligent Manufacture, and Industrial Automation (ICAMIMIA)

作者： Alfisena Juwandana Estiyanti Ekawati Eko Mursito Budi Indah Radityo Putri Komarudin Kudiya Instrumentation and Control Graduate Program Institut Teknologi Bandung Bandung Indonesia Departement of Engineering Physics Engineering Physics Research Group Institut Teknologi Bandung Bandung Indonesia Rumah Batik Komar Bandung Indonesia

This study researches the fusion of Indonesian traditional batik art with modernity called the Batik Pendulum. A machine based on Cable-Driven Parallel Robot (CDPR) architecture has been developed to automate the process of Batik Pendulum drawing. The suspended CDPR design uses four cables to provide flexibility and space efficiency. An artist may draw rough pendulum patterns utilizing a tablet as a human interface, which are then coded into coordinate-based code and sent to a microcontroller. The microcontroller drives four stepper motors to synchronize the length of the cables. Therefore, the platform carrying the wax can be moved to create the desired batik patterns. The machine was tested by dripping the paint on the fabric along the test path to validate the accuracy of the patterns. The Mean Absolute Percentage Error test results for the x, y, and radius axes were 1.63%, 1.95%, and 6.33%, while the maximum error values in the movement of the x, y, and radius axes were 8.64, 18.3, and 24.08 mm. This research represents a significant step in preserving Indonesia's cultural heritage while embracing contemporary creativity.

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