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Impact of Annealing on the Melt Recrystallization of a-PDLA/α-PLLA Double-layered Films

Chinese Journal of Polymer Science 2024年第2期42卷 230-238,I0009页

作者： Yun-Peng li hao-Ran Shen Shao-Juan Wang hao Zhang Jian Hu Rui Xin Xiao-li Sun Shou-Ke Yan Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-plasticsQingdao University of Science&TechnologyQingdao266042China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing100029China

Poly(lactic acid)(PLA) as a bio-based polymer with biodegradability and biocompatibility has attracted much attention. To manipulate its properties for different applications, regulation of crystal structure and crystalline morphology becomes an attractive research topic. In this work, the structure evolution of layered samples containing an amorphous poly(D-lactide)(PDLA) layer and a crystalline poly(L-lactide)(PLLA)layer with highly oriented edge-on α lamellar crystals after annealing at 150 ℃ or/and after melt-recrystallization has been studied by AFM, FTIR,and TEM combined with electron diffraction. The results demonstrate that melt recrystallization of the as-prepared sample leads to the formation of abundant randomly oriented PLA stereo-complex(PLA SC) crystals. Annealing at 150 ℃ results in the formation of a small amount of oriented PLA SC crystals at the interface. These PLA SC crystals show great impact on the recrystallization behavior of sample after melting at 190 ℃ and then crystallizing at 90 ℃. First, they impede the mutual diffusion of the overlying PDLA and underlying PLLA, and thus reduce their stereocomplexation ability as manifested by the decreased amount of PLA SC crystals. Second, they act as substrate to initiate the epitaxial crystallization of the overlying PDLA and underlying PLLA, which ensures the production of a highly oriented structure of PDLA and PLLA after melt recrystallization again.

关键词： Poly(L-lactide) Poly(D-lactide) Double layer Stereocomplex

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Frequency and risk factors of psychological distress among individuals with epilepsy before and during the outbreak of the SARS-CoV-2 Omicron variant in China:an online questionnaire survey

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Acta Epileptologica 2024年第1期7卷 36-43页

作者： Xiaoting hao Qi Zhang Chenxi zhong Enzhi li Yingqi Jiang Jiajun Xu Yuanyuan li Dong Zhou Bo Yan Department of Neurology West China HospitalSichuan University No37 Guoxue AlleyChengduSichuan Province610000China Department of Psychiatry and Mental Health West China HospitalSichuan University/West China School of Clinical MedicineSichuan UniversityChengdu610000China Department of Neurology Chengdu Shangjin Nanfu HospitalChengdu611730China West China School of Nursing Sichuan University Chengdu610000China Department of Clinical Research Management West China HospitalSichuan UniversityChengdu610000China

Background The COVID-19 pandemic substantially increases the risk of severe psychological distress among people with epilepsy(PWE),especially those with monthly household income12 should consult a psychiatrist,especially during major *** study was aimed to compare the frequency of psychological distress among Chinese PWE before and during the outbreak of the SARS-CoV-2 Omicron variant,and to identify risk factors for such *** In this prospective study,we collected sociodemographic data of PWE aged>14 years,who were treated at our center during December 1 to 15,*** participants completed the 6-item Kessler Psychological Distress Scale before the outbreak and again during the *** visitors who were unrelated to those patients during the outbreak were included as a *** logistic regression analysis was performed to identify risk factors of severe psychological distress and its *** Of the 223 PWE,127 were tested positive for SARS-CoV-2,while 174 of 218 controls were positive for *** neurological symptoms were similar between PWE and controls with *** average Kessler score of PWE was significantly higher during the outbreak than before it(9.93±3.98 vs.8.52±0.23,P<0.001).The average score of controls during the outbreak(5.146±0.35,P<0.001)was significantly lower than that of the *** identified three independent predictors for severe psychological distress in PWE during the outbreak,i.e.,monthly household income<5000 RMB(OR=0.252,95%CI 0.064–0.998,P=0.048),severe psychological distress before the outbreak(OR=0.067,95%CI 0.026–0.174,P<0.001),and seizure onset within 30 days before the assessment during the outbreak(OR=0.356,95%CI 0.157–0.805,P=0.013).Of the three predictors,the last one was also an independent predictor for exacerbation of psychological distress during the outbreak(OR=0.302,95%CI 0.123–0.741,P

关键词： Epilepsy Neurological symptoms Psychological distress COVID-19 pandemic

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Thermal fatigue and wear of compacted graphite iron brake discs with various thermomechanical properties

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China Foundry 2024年第3期21卷 248-256页

作者： Gui-quan Wang Zhuo Xu zhong-li liu Xiang Chen Yan-xiang li School of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai 264005ShandongChina School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China

The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake *** this work,the thermal fatigue and wear of compacted graphite iron brake discs were investigated,aiming to provide an experimental foundation for achieving a balance between their thermal and mechanical *** graphite iron brake discs with different tensile strengths,macrohardnesses,specific heat capacities and thermal diffusion coefficients were produced by changing the proportion and strength of *** peak temperature,pressure load and friction coefficient of compacted graphite iron brake discs were analyzed through inertia friction *** morphology of thermal cracks and 3D profiles of the worn surfaces were also *** is found that the thermal fatigue of compacted graphite iron discs is determined by their thermal properties.A compacted graphite iron with the highest specific heat capacity and thermal diffusion coefficient exhibits optimal thermal fatigue *** of the matrix at low temperatures significantly weakens the function of alloy strengthening in hindering the propagation of thermal *** the reduced hardness,increasing the ferrite proportion can mitigate wear loss resulting from low disc temperatures and the absence of abrasive wear.

关键词： compacted graphite iron brake disc thermomechanical properties thermal fatigue wear

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Modelling and Temperature Control of liquid Cooling Process for lithium-Ion Battery

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Journal of Thermal Science 2024年第5期33卷 1794-1808页

作者： li Guanru zhong Yangfan BAO Chujin CHEN Yongping ZHANG Chengbin School of Energy and Environment Southeast UniversityNanjing 210096China Key Laboratory of Efficient Low-Carbon Energy Conversion and Utilization of Jiangsu Provincial Higher Education Institutions Suzhou University of Science and TechnologySuzhou 215009China Alibaba Cloud Computing Co.Ltd. Hangzhou 311121China Zhejiang Immertech Co.Ltd. Hangzhou 310000China

Efficient thermal management of lithium-ion battery,working under extremely rapid charging-discharging,is of widespread interest to avoid the battery degradation due to temperature rise,resulting in the enhanced ***,thermal management of lithium-ion battery has been performed via a liquid cooling theoretical model integrated with thermoelectric model of battery packs and single-phase heat *** to alleviate the battery temperature fluctuation by automatically manipulating the flow rate of working fluid,a nominal model-free controller,i.e.,fuzzy logic controller is *** optimized on-off controller based on pump speed optimization is introduced to serve as the comparative *** control simulations are conducted under regular operating and extreme operating conditions,and two controllers are applied to control battery temperature with proper intervals which is conducive to enhance the battery charge-discharge *** results indicate that,for any operating condition,the fuzzy logic controller shows excellence in terms of the tracking accuracy of set-point of battery *** to the establishment of fuzzy set and fuzzy behavioral rules,the battery temperature has been throughout maintained near the set point,and the temperature fluctuation amplitude is highly reduced,with better temperature control accuracy of~0.2℃(regular condition)and~0.5℃(extreme condition)compared with~1.1℃(regular condition)and~1.6℃(extreme condition)of optimized on-off *** in the case of extreme operating condition,the proposed optimized on-off controller manifests the hysteresis in temperature fluctuation,which is ascribed to the set of dead-band for the feedback *** simulation results cast new light on the utilization and development of model-free temperature controller for the thermal management of lithium-ion battery.

关键词： temperature control battery thermal management model-free controller fuzzy logic control

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Uncertainty and disturbance estimator-based model predictive control for wet flue gas desulphurization system

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Chinese Journal of Chemical Engineering 2024年第3期67卷 182-194页

作者： Shan liu Wenqi zhong li Sun Xi Chen Rafal Madonski School of Energy and Environment Key Laboratory of Energy Thermal Conversion and Control of Ministry of EducationSoutheast UniversityNanjing 210096China Faculty of Automatic Control Electronics and Computer ScienceSilesian University of TechnologyGliwise 44-100Poland

Wet flue gas desulphurization technology is widely used in the industrial process for its capability of efficient pollution *** desulphurization control system,however,is subjected to complex reaction mechanisms and severe disturbances,which make for it difficult to achieve certain practically relevant control goals including emission and economic performances as well as system *** address these challenges,a new robust control scheme based on uncertainty and disturbance estimator(UDE)and model predictive control(MPC)is proposed in this *** UDE is used to estimate and dynamically compensate acting disturbances,whereas MPC is deployed for optimal feedback regulation of the resultant *** viewing the system nonlinearities and unknown dynamics as disturbances,the proposed control framework allows to locally treat the considered nonlinear plant as a linear *** obtained simulation results confirm that the utilization of UDE makes the tracking error negligibly small,even in the presence of unmodeled *** the conducted comparison study,the introduced control scheme outperforms both the standard MPC and PID(proportional-integral-derivative)control strategies in terms of transient performance and ***,the results reveal that a lowpass-filter time constant has a significant effect on the robustness and the convergence range of the tracking error.

关键词： Desulphurization system Disturbance rejection Model predictive control Uncertainty and disturbance estimator Nonlinear system

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Effect of matrix resin components on properties of the semi-conductive shielding material for high-voltage cable

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High Voltage 2024年第2期9卷 419-428页

作者： Guochang li Tianyao liu Xiaolong Chen Yanhui Wei Chuncheng hao Shengtao li Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

The semi-conductive shielding layer is an important part of the high-voltage cable,playing a role in uniform electric field and reducing the air gap at the *** overall performance of the cable is affected by the semi-conductive shielding layer with different base resin *** matrix resins of ethylene-vinyl acetate(EVA),ethylene-ethyl acrylate(EEA)and ethylene-butyl acrylate(EBA)were used to prepare the semi-conductive shielding materials of CB/EVA,CB/EEA and CB/*** influences of different matrix resins on the chemical,electrical,thermal and mechanical properties of the shielding materials were *** results show that CB has the best dispersion in EBA resin and the worst dispersion in EEA *** temperature in-flection points of CB/EVA,CB/EEA and CB/EBA shielding materials are 90°C,100°C and 110°C,respectively,and the CB/EBA shielding material has the lowest resistivity and the weakest positive temperature coefficient effect at room *** thermal conductivity of all three matrix resins is smaller than that of the shielding material,the thermal conductivity of CB/EVA and CB/EBA shielding materials show a slow increase with temperature,and the CB/EEA shielding material is the least affected by the *** mechanical properties of the three matrix resins and the three shielding materials are EBA>EVA>EEA,among them the stress of CB/EBA shielding material is 31.0 MPa and the strain is 570%.This work has important reference significance for the selection of shielding layer matrix resin and material formulation in engineering applications.

关键词： temperature. resin resins

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Robust-augmentation nonlinear dynamic inversion control of over-actuated coaxial high-speed helicopter in transition mode

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Chinese Journal of Aeronautics 2024年第8期37卷 404-420页

作者： Yuqing QIU Yan li Jinxi LANG Yuxian liU zhong WANG School of Automation Northwestern Polytechnical UniversityXi’an 710129China

As the elevator and rudder can be used actively for control,in addition to the rotors,Coaxial High-speed Helicopters(CHHs)have the problems of control redundancy and changing control authority in the transition *** paper presents a robust-augmentation transitioning flight control design for a CHH under the adverse conditions of parametric uncertainties and external ***,based on control characteristic analysis,an Adaptive Filtered Nonlinear Dynamic Inversion(AFNDI)controller is proposed for the angular rate to handle the effect of unknown unstructured uncertainties and external *** analysis proves that the presented angular rate controller can guarantee steady-state and transient ***,the attitude angle and velocity controllers are also ***,an Incremental-based Nonlinear Prioritizing Control Allocation(INPCA)method is designed to take into account control surface transition and changing control authority,which efficiently distributes the required moments between coaxial rotors and aero-surfaces,and avoids the control reversal problem of the yaw *** the proposed control architecture,the low-pass filter is introduced to alleviate the adverse influence of time delay and measurement ***,the effectiveness of the proposed controller is demonstrated through nonlinear numerical simulations,and is compared with existing *** results show that the proposed control law can improve both capabilities of disturbance rejection and fast response,and works satisfactorily for the CHH transitioning control characteristic.

关键词： Coaxial high-speed helicopter Transition mode Attitude control Control allocation Robust adaptive control

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A bifunctional POM-based Cu-viologen complex with mixed octamolybdate clusters for rapid oxidation desulfurization and effective photogeneration of hydrogen

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Rare Metals 2024年第1期43卷 236-246页

作者： lin Yang zhong Zhang Chao-Nan Zhang Xiu-li Wang College of Chemistry and Materials Engineering Bohai UniversityJinzhou 121013China Professional Technology Innovation Center of liaoning Province for Conversion Materials of Solar Cell Bohai UniversityJinzhou 121013China

The design and synthesis of catalysts for the oxidation desulfurization and production of hydrogen are extremely important for solving environmental pollution and energy ***,a novel bifunctional [α-Mo_(8)O_(26)]^(4-)/[β-Mo_(8)O_(26)]^(4-)-based Cu-viologen complex H_(4)[Cu_(2)~ⅠCl_(2)(Hbcbpy)_(4)] [α-Mo_(8)O_(26)] [β-Mo8O_(26)]·H_(2)O(BHU-2,Hbcbpy=1-(4-carboxybenzyl)-4,4'-bipyridinium) was synthesized and characterized by single-crystal X-ray diffraction(XRD),infrared radiation spectra,powder X-ray diffraction(PXRD) and X-ray photoelectron spectroscopy(XPS) *** structural characteristic of BHU-2 is the presence of two types of octamolybdate clusters [α-Mo_(8)O_(26)]^(4-)/[β-Mo_(8)O_(26)]^(4-)and a new binuclear Cu~Ⅰ-Hbcbpy complex linked by Cl-bridges[Cu_(2)ⅠCl_(2)(Hbcbpy)_(4)]^(4+).BHU-2 as a heterogeneous catalyst exhibits excellent activities to the oxidation desulfurization and photocatalytic hydrogen *** room temperature,BHU-2 can catalyze 96% conversion of methyl phenyl sulfide with 98% selectivity,and the process obeys the pseudo-first-order reaction kinetic with the half-life of9.6 *** notorious 2-chloroethyl ethyl sulfide can achieve 99% conversion with 98% selectivity within only1 min at the presence of BHU-2,and the turnover frequency(TOF) is up to 7400 h^(-1).BHU-2 also exhibits high catalytic activity for the oxidation of other aromatic and aliphatic thioethers within short time at room ***,BHU-2 shows a high catalytic activity for visible-light-driven hydrogen evolution with an H_(2) evolution rate of 1677.85 μmol·g^(-1)·h^(-1) within 10 ***,the catalytic activities do not decrease evidently after three cycles,revealing the prominent structural stability and recyclability.

关键词： Polyoxometalate Metal-organic complex Viologen Oxidation desulfurization Photocatalytic hydrogen production

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Cleaner production of 3.5 valent vanadium electrolyte from ammonium metavanadate by ammonia reduction-sulfuric acid dissolution method

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Tungsten 2024年第3期6卷 555-560页

作者： Cheng Wang Lan-Jie li hao Du College of Chemical Engineering University of Chinese Academy of Sciences Institute of Process Engineering National Engineering Research Center of Green Recycling for Strategic Metal Resources Chinese Academy of Sciences Hesteel Group Company limited

The vanadium redox flow battery(VRFB) has been widely used in large-scale energy storage areas due to the advantages of long lifespan and high safety. However, the high preparation cost of vanadium electrolyte limits ... 详细信息

关键词： Ammonia

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LFM Radar Source Passive Localization Algorithm Based on Range Migration

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Journal of Beijing Institute of Technology 2024年第2期33卷 130-140页

作者： Dandan li Deyi Wang hao Huan Beijing Key Laboratory of Fractional Signals and Systems School of Information and ElectronicsBeijing Institute of TechnologyBeijing 100081China Beijing Aerospace Automatic Control Institute Beijing 100854China

Traditional single-satellite passive localization algorithms are influenced by frequency and angle measurement accuracies,resulting in error estimation of emitter position on the order of ***,a single-satellite localization algorithm based on passive synthetic aper-ture(PSA)was introduced,enabling high-precision ***,its estimation of azimuth and range distance is considerably affected by the residual frequency offset(RFO)of uncoopera-tive system ***,it requires data containing a satellite flying over the radia-tion source for RFO *** estimating the RFO,an accurate estimation of azimuth and range distance can be carried out,which is difficult to achieve in practical *** LFM radar source passive localization algorithm based on range migration is proposed to address the dif-ficulty in estimating frequency *** algorithm first provides a rough estimate of the pulse repetition time(PRT).It processes intercepted signals through range compression,range interpola-tion,and polynomial fitting to obtain range migration ***,it uses the changing information of range migration and an accurate PRT to formulate a system of nonlinear equations,obtaining the emitter position and a more accurate PRT through a two-step localization *** offset only induces a fixed offset in range migration,which does not affect the changing *** algorithm can also achieve high-precision localization in squint ***,the effectiveness of this algorithm is verified through simulations.

关键词： passive localization range migration residual frequency offset

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