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A novel method for extracting and optimizing the complex permittivity of paper-based composites based on an artificial neural network model

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Science china Technological Sciences 2024年第10期67卷 3190-3204页

作者： XIA ChenBin SHEN JunYi LIAO ShaoWei WANG Yi HUANG ZhengSheng XUE Quan TANG Min LONG Jin HU Jian School of Light Industry and Engineering South China University of Technology School of Electronic and Information Engineering South China University of Technology

Measuring the complex permittivity of ultrathin, flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods, and verifying the accuracy of test results remains difficult. In this study, we introduce a methodology based on a back-propagation artificial neural network(ANN) to extract the complex permittivity of paper-based composites(PBCs). PBCs are ultrathin and flexible materials exhibiting considerable complex permittivity and dielectric loss tangent. Given the absence of mature measurement methods for PBCs and a lack of sufficient data for ANN training, a mapping relationship is initially established between the complex permittivity of honeycomb-structured microwave-absorbing materials(HMAMs, composed of PBCs) and that of PBCs using simulated data. Leveraging the ANN model, the complex permittivity of PBCs can be extracted from that of HMAMs obtained using standard measurement. Subsequently, two published methods are cited to illustrate the accuracy and advancement of the results obtained using the proposed approach. Additionally, specific error analysis is conducted, attributing discrepancies to the conductivity of PBCs, the homogenization of HMAMs, and differences between the simulation model and actual objects. Finally, the proposed method is applied to optimize the cell length parameters of HMAMs for enhanced absorption performance. The conclusion discusses further improvements and areas for extended research.

关键词： paper-based composite honeycomb complex permittivity artificial neural networks inverse modeling

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Intense and Superflat White Laser with 700-nm 3-dB Bandwidth and 1-mJ Pulse Energy Enabling Single-Shot Subpicosecond Pulse Laser Spectroscopy

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Research 2024年第2期6卷 319-327页

作者： Lihong Hong Haiyao Yang Liqiang Liu Mingzhou Li Yuanyuan Liu Baoqin Chen Huakang Yu Wenbo Ju Zhi-Yuan Li School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510641China State Key Laboratory of Luminescent Materials and Devices South China University of TechnologyGuangzhou 510640China

An optical spectrometer is a basic spectral instrument that probes microscopic physical and chemical properties of macroscopic objects but generally suffers from difficulty in broadband time-resolved *** this work,we report the creation of ultrabroadband white-light laser with a 3-dB bandwidth covering 385 to 1,080 nm,pulse energy of 1.07 mJ,and pulse duration of several hundred femtoseconds by passing 3-mJ pulse energy,50-fs pulse duration Ti:Sapphire pulse laser through a cascaded fused silica plate and chirped periodically poled lithium niobate *** utilize this unprecedented superflat,ultrabroadband,and intense femtosecond laser light source to build a single-shot(i.e.,single-pulse)subpicosecond pulse laser ultraviolet-visible-near-infrared spectrometer and successfully measure various atomic and molecular absorption *** single-shot ultrafast spectrometer may open up a frontier to monitor simultaneously the ultrafast dynamics of multiple physical and chemical processes in various microscopic systems.

关键词： Pulse utilize frontier

Competition of Composition Fluctuation Modes in Weakly Segregated Salt-doped Symmetric Diblock Copolymers

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Chinese Journal of Polymer Science 2024年第9期42卷 1375-1385,I0008页

作者： Yuan-Xin Zhou Xian Kong south china Advanced Institute for Soft Matter Science and technology School of Emergent Soft MatterSouth China University of TechnologyGuangzhou510640China Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices South China University of TechnologyGuangzhou510640China

Salt-doped block copolymers have widespread applications in batteries,fuel cells,semiconductors,and various industries,where their properties crucially depend on phase separation ***,investigations into salt-doped diblock copolymers have predominantly focused on microphase separation,overlooking the segregation between ionic and polymeric *** study employs weak segregation theory to explore the interplay between phase separation dominated by the polymer-modulated mode and the salt-out-modulated mode,corresponding to microscopic and macroscopic phase separations,*** comparing diblock copolymers doped with salts to those doped with neutral solvents,we elucidate the significant role of charged species in modulating phase *** phase separation mode exhibits a transition between the polymer-modulated and salt-out-modulated modes at different *** systems doped with neutral solvents,this transition is stepwise,while in salt-ion-doped systems,it is *** a sufficiently large Flory-Huggins parameter between ions and polymers,the salt-out-modulated mode becomes dominant,promoting macrophase *** to the solvation effect of salt ions,salt-doped systems are more inclined to undergo microphase ***,we explore factors influencing the critical wavenumber of phase separation,including doping level and the Flory-Huggins parameters between two blocks and between ions and polymeric *** findings reveal that in a neutral solvent environment,these factors alter only the boundary between micro-and macro-phase separations,leaving the critical wavenumber unchanged in microphase separation ***,in a salt-doped environment,the critical wavenumber of microphase separation varies with these *** provides valuable insights into the pivotal role of electrostatics in the phase separation of salt-doped block copolymers.

关键词： Block copolymer Phase separation Field theory Salt-doped

Sub-nanosized vanadate hybrid clusters maintain glucose homeostasis and restore treatment response in inflammatory disease in obese mice

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Nano Research 2024年第3期17卷 1818-1826页

作者： Kun Chen Shengqiu Liu Yujun Wei south china Advanced Institute for Soft Matter Science and technology School of Emergent Soft MatterSouth China University of TechnologyGuangzhou 510641China Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing South China University of TechnologyGuangzhou 510641China Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices South China University of TechnologyGuangzhou 510641China

Obesity is closely related with insulin resistance and chronic ***,we report that unsaturated lipid-modified polyoxovanadates(ULPOVs)can restrict weight gain of diet-induced obese mice and improve their glycemic control and obesity-associated *** administration of the sub-nanosized ULPOVs at a low dosage for 7 weeks reduces the body weight and almost normalizes the blood glucose levels of obese mice fed on a high-fat *** treatment increases the activity of the nuclear receptor peroxisome proliferator-activated receptorγ(PPARγ)and reduces intestinal caloric intake,which may be the main reason for blood sugar and body weight *** addition to insulin-sensitizing,PPARγactivation induced by ULPOV treatment in obese mice with atopic dermatitis(AD)promotes the type 2 T helper(TH_(2))cell selective responses and therapeutic effects on immune dysregulation caused by *** data suggest sub-nanosized polyoxovanadate clusters as a class of potential candidates to relieve symptoms accompanied by diet-induced obesity.

关键词： polyoxovanadates lipid modification glucose homeostasis obesity inflammatory disease peroxisome proliferator-activated receptorγ(PPARγ)

Properties of collective flow and pion production in intermediate-energy heavy-ion collisions with a relativistic quantum molecular dynamics model

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Nuclear Science and Techniques 2024年第1期35卷 155-169页

作者： Si-Na Wei Zhao-Qing Feng School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(***). Using the ***, the properties of collective flow and pion production were investigated systematically for nuclear reactions with various isospin asymmetries. The directed and elliptic flows of the *** are able to describe the experimental data of STAR Collaboration. The directed flow difference between free neutrons and protons was associated with the stiffness of the symmetry energy, that is, a softer symmetry energy led to a larger flow difference. For various collision energies, the ratio between the π^(-) and π^(+) yields increased with a decrease in the slope parameter of the symmetry energy. When the collision energy was 270 MeV/nucleon, the single ratio of the pion transverse momentum spectra also increased with decreasing slope parameter of the symmetry energy in both nearly symmetric and neutron-rich ***, it is difficult to constrain the stiffness of the symmetry energy with the double ratio because of the lack of threshold energy correction on the pion production.

关键词： Heavy-ion collision Collective flow Pion production Symmetry energy Relativistic mean field

High Power Density EV Integrated Fast Battery Chargers Based on the General Torque Cancelation Law for Three-Phase Motors

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 756-766页

作者： Yanxiong Lei Guiping Du Tuhuan Li Wenjie Ma Xueyi Wang School of Electric Power South China University of TechnologyGuangzhou 510641China

Integrated battery chargers are highly effective for saving costs and improving the power density of on-board chargers in electric vehicles (EVs), However, achieving torque elimination of the commonly used three-phase (3p) motors during the fast-charging process is challenging. In this paper, the general torque cancelation law applied in 3p permanent magnet synchronous motors (PMSMs) and induction motors (IMs) is derived to design high power density integrated fast battery chargers. Two novel integrated systems with fast-charging and vehicle-to-grid (V2G) capabilities are proposed based on this law. The main advantages of the proposed systems are: (1) Two filter inductors are constituted by the stator windings while charging, and only one external inductor and several contactors are supplemented to the motor-drive circuit. Therefore, the proposed integrated systems possess high power density;(2) The 3p open-winding (OW) motor is employed, with no need to modify the propulsion system or redesign the interior structure of the motor;(3) Employing an individual controller for each phase of the inner current loop control, the proposed systems realize unity power factors and low current harmonics in the fast-charging and V2G mode. Simulation and experimental results verify the feasibility of the proposed topologies and control strategies.

关键词： Electric vehicles(EVs) fast charging integrated battery charger 3p PMSM/IM torque cancelation

A global model of intensity autocorrelation to determine laser pulse duration

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Chinese Physics B 2024年第5期33卷 446-451页

作者：彭雨菲刘励强洪丽红李志远 School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

We present a new global model of collinear autocorrelation based on second harmonic generation *** model is rigorously derived from the nonlinear coupled wave equation specific to the autocorrelation measurement configuration,without requiring a specific form of the incident pulse function.A rigorous solution of the nonlinear coupled wave equation is obtained in the time domain and expressed in a general analytical *** global model fully accounts for the nonlinear interaction and propagation effects within nonlinear crystals,which are not captured by the classical local *** assess the performance of the global model compared to the classic local model,we investigate the autocorrelation signals obtained from both models for different incident pulse waveforms and different full-widthes at half-maximum(FWHMs).When the incident pulse waveform is Lorentzian with an FWHM of 200 fs,the global model predicts an autocorrelation signal FWHM of 399.9 fs,while the classic local model predicts an FWHM of 331.4 *** difference between the two models is 68.6 fs,corresponding to an error of 17.2%.Similarly,for a sech-type incident pulse with an FWHM of 200 fs,the global model predicts an autocorrelation signal FWHM of 343.9 fs,while the local model predicts an FWHM of 308.8 *** difference between the two models is 35.1 fs,with an error of 10.2%.We further examine the behavior of the models for Lorentzian pulses with FWHMs of 100 fs,200 fs and 500 *** differences between the global and local models are 17.1 fs,68.6 fs and 86.0 fs,respectively,with errors approximately around 17%.These comparative analyses clearly demonstrate the superior accuracy of the global model in intensity autocorrelation modeling.

关键词： intensity autocorrelation global model ultrashort pulses pulse-width measurement

Urban Flood Mitigation Strategies with Coupled Gray–Green Measures: A Case Study in Guangzhou City, china

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International Journal of Disaster Risk Science 2024年第3期15卷 467-479页

作者： Jiayue Li Jiajun Zeng Guoru Huang Wenjie Chen School of Civil Engineering and Transportation South China University of Technology School of Architecture South China University of Technology State Key Laboratory of Subtropical Building and Urban Science South China University of Technology College of Water Conservancy and Civil Engineering South China Agricultural University

The integration of gray and green infrastructure has proven to be a feasible approach for managing stormwater in established urban areas. However, evaluating the specific contributions of such coupled strategies is challenging. This study introduced a novel integrated hydrological-hydrodynamic model that takes into account the layout of low-impact development(LID)facilities along with pipeline alignment and rehabilitation. Reliable results from modeling were used to assess the individual contribution of LID and improved drainage facilities to urban flooding mitigation. We selected a natural island in Guangzhou City, china, as the study site. The results indicate that combining three LID measures, namely green roofs, sunken green spaces, and permeable pavements, can reduce total runoff by 41.7% to 25.89% for rainfall recurrence periods ranging from 1year to 100 years, and decrease the volume of nodal overflow by nearly half during rainfall events of less than 10-year return period. By integrating LID measures with the upgraded gray infrastructure, the regional pipeline overloading condition is substantially alleviated, resulting in a significant improvement in pipeline system resilience. For urban flooding control, it is recommended to integrate sufficient green space and avoid pipe-laying structural issues during urban planning and construction. The findings may assist stakeholders in developing strategies to best utilize gray and green infrastructure in mitigating the negative eff ects of urban flooding.

关键词： Coupled hydrodynamic model Gray–green approach Guangzhou City LID Pipe renovation Urban inundation

Tactile-sensing-based robotic grasping stability analysis

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Science china(Technological Sciences) 2024年第6期67卷 1817-1828页

作者： HUANG YanJiang WANG HaoNan ZHANG XianMin Guangdong Provincial Key Laboratory of Precision Equipment and Manufacturing technology South China University of TechnologyGuangzhou510640China

Tactile signals play a crucial role in enabling robots to successfully manipulate unfamiliar *** robots to grasp unknown objects securely and without causing damage,it is essential that they can analyze grasping stability in real time through tactile signals and respond *** study introduces a novel method for analyzing the stability of robotic hand grasping,utilizing the Wilcoxon signed rank *** efficacy of this method is demonstrated through its static and dynamic performance,and evaluated across a series of *** findings of this research highlight the method’s ability to accurately detect when an object begins to slip from the robot’s *** this method allows the gripper to maintain a secure hold on objects by applying the minimal necessary *** also enables the gripper to dynamically adjust the force it applies in real time,thus preventing the object from slipping during the movement of the robotic ***,the gripper demonstrates the ability to stably grasp objects of varied weights and with unknown characteristics,showcasing the versatility and effectiveness of the proposed method.

关键词： grasping stability manipulation tactile sensors