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Flow excitation mechanisms of unbalanced impeller forces after pump power-trip of ultra-high head pump-turbines

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Science China(Technological Sciences) 2024年第5期67卷 1602-1611页

作者： FU XiaoLong LI DeYou lv JingWei YANG Biao WANG HongJie WEI XianZhu School of Energy Science and Engineering Harbin Institute of TechnologyHarbin150001China State Key Laboratory of Hydro-Power Equipment Harbin Institute of Large Electrical MachineryHarbin150040China

To elucidate the dynamic mechanisms of unbalanced impellers in ultra-high head pump-turbines(PTs),this study employed a one-and three-dimensional coupled method to simulate the pump power-trip(PPT)process of an ultra-high head *** investigation revealed two novel pulsation frequency components,denoted as fDVand fINFT,associated with impeller *** pulsation intensities of these components were markedly higher than those of rotor-stator interaction frequency components in ultra-high head ***,the fDVcomponents exhibited pulsations at 1–2 times the rated rotation frequency of the impeller,spanning the entire transition ***,the fINFTcomponents constituted a complex frequency band with various frequency values,primarily occurring near conditions(Q=0,n=0,M=0,and d M/dt=0).These two pulsation frequency components were predominantly linked to the unsteady evolution of dean vortices inside the volute and complex transitions of the flow pattern within the impeller,*** is crucial to note that these unbalanced flow-induced impeller axial forces can elevate the risk of accidents where the rotor is subjected to significant upwind axial *** findings offer valuable insights into mitigating the risk of rotor lifting due to axial forces during PT events in ultra-high head PTs.

关键词： ultra-high head pump-turbine pump power-trip unbalanced impeller forces pressure pulsations flow pattern transitions

A Hybrid Integrated and Low-Cost Multi-Chip Broadband Doherty Power Amplifier Module for 5G Massive MIMO Application

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Engineering 2024年第7期38卷 223-232页

作者： Fei Huang Guansheng lv Huibo Wu Wenhua Chen Zhenghe Feng Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)*** inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small *** proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 *** gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 *** measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.

关键词： 5G Doherty power amplifier Multi-input multi-output Multi-chip modules Hybrid integrated

Ultra-high sensitivity fiber optic microphone with corrugated graphene-oxide diaphragm for voice recognition

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Nano Research 2024年第8期17卷 7593-7602页

作者： Yang Liu Cheng Li Lingxiao Yu Zhengwei Wu Shangchun Fan Ruitao lv School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China Shenzhen Institute of Beihang University Shenzhen 518063China Key Laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100190China

To avoid interference from unexpected background noises and obtain high fidelity voice signal,acoustic sensors with high sensitivity,flat frequency response,and high signal-to-noise ratio(SNR)are urgently needed for voice ***(GO)has received extensive attention due to its advantages of controllable thickness and high fracture ***,low mechanical sensitivity(SM)introduced by undesirable initial stress limits the performance of GO material in the field of voice *** alleviate the aforementioned issue,GO diaphragm with annular corrugations is *** means of the reusable copper mold machined by picosecond laser,the fabrication and transfer of corrugated GO diaphragm are realized,thus achieving a Fabry–Perot(F–P)acoustic *** from the structural advantage of the corrugated GO diaphragm,our F–P acoustic sensor exhibits high S_(M)(43.70 nm/Pa@17 kHz),flat frequency response(−3.2 to 3.7 dB within 300–3500 Hz),and high SNR(76.66 dB@1 kHz).In addition,further acoustic measurements also demonstrate other merits,including an excellent frequency detection resolution(0.01 Hz)and high time stability(output relative variation less than 6.7%for 90 min).Given the merits presented before,the fabricated F–P acoustic sensor with corrugated GO diaphragm can serve as a high-fidelity platform for acoustic detection and voice *** conjunction with the deep residual learning framework,high recognition accuracy of 98.4%is achieved by training and testing the data recorded by the fabricated F–P acoustic sensor.

关键词： corrugated graphene-oxide(GO)diaphragm Fabry-Perot(F-P)acoustic sensor mechanical sensitivity voice recognition

Overcoming the Na-ion conductivity bottleneck for the cost-competitive chloride solid electrolytes

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Journal of Energy Chemistry 2024年第8期95卷 1-8,I0001页

作者： lv Hu Hui Li Fang Chen Yating Liu Jinzhu Wang Cheng Ma Hefei National Research Center for Physical Sciences at the Microscale CAS Key Laboratory of Materials for Energy ConversionDepartment of Materials Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026AnhuiChina National Synchrotron Radiation Laboratory Hefei 230026AnhuiChina

Chloride solid electrolytes possess multiple advantages for the construction of safe,energy-dense allsolid-state sodium batteries,but presently the chlorides with sufficiently high cost-competitiveness for commercialization almost all exhibit low Na-ion conductivities of around 10^(-5)S cm^(-1)or ***,we report a chloride solid electrolyte,Na_(2.7)ZFCl_(5.3)O_(0.7),which reaches a Na-ion conductivity of 2.29×10^(-4)S cm^(-1)at 25℃without involving overly expensive raw materials such as rare-earth chlorides or Na_(2)*** addition to the efficient ion transport,Na_(2.7)ZrCl_(5.3)O_(0.7)also shows an excellent deformability surpassing that of the widely studied Na_(3)PS_(4),Na_(3)SbS_(4),and Na_(2)ZrCl_(6)solid *** combination of these advantages allows the all-solid-state cell based on Na_(2.7)ZrCl_(5.3)O_(0.7)and NaCrO_(2)to realize stable room-temperature cycling at a much higher specific current than those based on other non-viscoelastic chloride solid electrolytes in literature(120 mA g^(-1)vs.12-55 mA g^(-1));after 100 cycles at such a high rate,the Na_(2.7)ZFCl_(5.3)O_(0.7)-based cell can still deliver a discharge capacity of 80 mAh g^(-1)at25℃.

关键词： All-solid-state sodium batteries Ionic conductivities Solid electrolytes Chlorides High voltage stability

Characteristics of water alternating CO_(2)injection in low-permeability beach-bar sand reservoirs

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Energy Geoscience 2024年第1期5卷 224-229页

作者： Maolei Cui Rui Wang Zengmin Lun Chengyuan lv State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Beijing100083China Key Laboratory of Marine Oil and Gas Reservoir Production SINOPECBeijing100083China Petroleum Exploration and Development Research Institute SINOPECBeijing100083China

Water flooding can be ineffective in highly heterogeneous low-permeability beach-bar sand *** introduction of CO_(2)flooding helps boost the oil production of the reservoirs but only in an early *** the late stage of flooding,gas channeling would *** alternating gas(CO_(2))(WAG)process can be used to delay gas channeling and improve the effect of CO_(2)injection,though its adaptability to beach-bar sand reservoirs remains *** order to clarify CO_(2)injection characteristics in these reservoirs,experiments were carried out in high-temperature high-pressure NMR on-line displacement experiment apparatus to simulate different flooding modes on synthetic cores that can reflect the vertical heterogeneity of beach-bar *** CO_(2)injection modes were implemented on these cores and the displacement characteristics and residual oil distribution features during both WAG injection and continuous CO_(2)injection were analyzed quantitatively and *** results show that the scheme of WAG injection after continuous CO_(2)injection can obtain better oil displacement efficiency than that of the scheme of continuous CO_(2)injection after WAG injection,but there is no significant difference in respect of oil displacement efficiency of WAG flooding between the mode of bar-injection e beach-production(injection into bar sand e production from beach sand)and the mode of beach-injection e beach-production(injection into and production from beach sand),with the former mode having a higher oil recovery *** wider pore-size distribution range of microscopic residual oil after WAG injection shows great potential of enhancing oil recovery from subsequent continuous gas *** WAG injection is implemented prior to continuous CO_(2)injection,the displacement effect of the latter is more *** research may provide a theoretical basis for CO_(2)EOR in this type of reservoirs.

关键词： Beach-bar sand Low permeability CO_(2)injection WAG NMR

Effective protective agents against the organ toxicity of T-2 toxin and corresponding detoxification mechanisms:A narrative review

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Animal Nutrition 2024年第1期16卷 251-266页

作者： Pengju Wang lv-hui Sun Xu Wang Qinghua Wu Aimei Liu Hubei Key Laboratory of Diabetes and Angiopathy Medicine Research InstituteXianning Medical CollegeHubei University of Science and TechnologyXianning 437100China Hubei Hongshan Laboratory College of Animal Science and TechnologyHuazhong Agricultural UniversityWuhan430070China National Reference Laboratory of Veterinary Drug Residues(HZAU)and MAO Key Laboratory for Detection of Veterinary Drug Residues Huazhong Agricultural UniversityWuhan430070China College of Life Science Yangtze UniversityJingzhou 434025China

T-2 toxin is one of the most widespread and toxic fungal toxins in food and *** can cause gastrointestinal toxicity,hepatotoxicity,immunotoxicity,reproductive toxicity,neurotoxicity,and nephrotoxicity in humans and animals.T-2 toxin is physicochemically stable and does not readily degrade during food and feed ***,suppressing T-2 toxin-induced organ toxicity through antidotes is an urgent *** agents against the organ toxicity of T-2 toxin have been recorded widely in the literature,but these protective agents and their molecular mechanisms of detoxification have not been comprehensively *** this review,we provide an overview of the various protective agents to T-2 toxin and the molecular mechanisms underlying the detoxification *** appropriate targets to antagonize T-2 toxin toxicity is also an important *** review will provide essential guidance and strategies for the better application and development of T-2 toxin antidotes specific for organ toxicity in the future.

关键词： T-2 toxin Organ toxicity Protective agent Detoxification mechanism

Additive-free synthesis of S-substituted isothioureas via visible-light-induced four-component reaction ofα-diazoesters,aryl isothiocyanates,amines and cyclic ethers

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Chinese Chemical Letters 2024年第2期35卷 415-419页

作者： Yufen lv Hongyu Ding Jinmao You Wei Wei Dong Yi Key Laboratory of Catalytic Conversion and Clean Energy in Universities of Shandong Province School of Chemistry and Chemical EngineeringQufu Normal UniversityQufu 273165China College of Chemistry and Chemical Engineering Shaoxing UniversityShaoxing 312000China School of Pharmacy Southwest Medical UniversityLuzhou 646000China

An additive-free and environmentally friendly strategy has been realized for the construction of S-substituted isothioureas through visible-light-induced multicomponent reaction starting fromα-diazoesters,aryl isothiocyanates,amines and cyclic *** methodology features simple operation,mild reaction conditions,favorable functional group tolerance,easily available starting materials and high efficiency.

关键词： Visible-light Additive-free Four-component reaction S-Substituted isothioureas

Crystal structure,phase transitions,and thermodynamic properties of magnesium metavanadate(MgV_(2)O_(6))

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Journal of Magnesium and Alloys 2024年第4期12卷 1449-1460页

作者： Guishang Pei Cheng Pan Dapeng Zhong Junyi Xiang Xuewei lv College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and Advanced Materials Chongqing UniversityChongqing 400044China Pangang Group Research Institute Co. Ltd.Panzhihua 617000China

As a promising anode material for magnesium ion rechargeable batteries,magnesium metavanadate(MgV_(2)O_(6))has attracted considerable research interest in recent years.A MgV_(2)O_(6)sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V2O5 powder under an air *** solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)occurred at 841 K and the enthalpy change was 4.37±0.04 kJ/*** endothermic effect at 1014 K and the enthalpy change was 26.54±0.26 kJ/mol,which is related to the incongruent melting ofβ-MgV_(2)O_(6).In situ XRD was performed to investigate phase transition of the as-prepared MgV_(2)O_(6)at high *** cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group,and the lattice parameters of a=9.280 A°,b=3.501 A°,c=6.731 A°,β=111.76°.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)was further studied by thermal kinetics,indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating ***,the enthalpy change of MgV_(2)O_(6)at high temperatures was measured utilizing the drop calorimetry,heat capacity was calculated and given as:Cp=208.3+0.03583T-4809000T^(−2)(298-923 K)(J mol^(−1)K^(−1)),the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV_(2)O_(6)at high temperatures.

关键词： MgV_(2)O_(6) Crystal structure Phase transitions Thermodynamic functions

Design and modification of metal sulfide-based catalysts for lithiumsulfur batteries

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Particuology 2024年第3期86卷 86-100页

作者： Yufei Zhao Chuannan Geng Li Wang Haotian Yang Wei lv Quan-Hong Yang Nanoyang Group State Key Laboratory of Chemical EngineeringSchool of Chemical Engineering and TechnologyNational Industry-Education Integration Platform of Energy Storageand Collaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin UniversityTianjin300072China Shenzhen Geim Graphene Center Engineering Laboratory for Functionalized Carbon MaterialsTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China Haihe Laboratory of Sustainable Chemical Transformations Tianjin300192China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityFuzhou350207China

Metal sulfide(MS)have good conductivity,strong adsorption ability,and excellent catalytic activity for the conversion of sulfur species,and thus,show great promise as the catalysts in LieS ***,the relationship between their properties and electrochemical performance is still ***,further in-depth discussions are required to improve their design in Li-S *** review systematically summarizes the basic structural and electrochemical properties of MSs and highlights the advantages that guarantee them as high-performance catalysts in Li-S ***,various modification strategies for MSs to enhance the catalytic activity,efficiency,and stability are also *** last,future opportunities for MS catalysts in Li-S batteries are proposed.

关键词： Lithium-sulfur battery Metal sulfide Catalysis