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Realizing the excellent oxidation resistance of an environmental barrier coating through aluminum surface modification

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Journal of Advanced Ceramics 2024年第7期13卷 976-986页

作者： lin Dong Wen-Qi Yang lin Chen Guan-Jun Yang Chang-Jiu li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Aerospace Engine Company limited in China Aerospace Science and Technology Corporation Xi’an 710065China

The lifetime of Si-based environmental barrier coatings(EBCs)is constrained by thermally grown SiO_(2)oxidelayer(SiO_(2)-TGO),which can cause premature cracking and *** address this issue,a new approach for surfacemodification using aluminum is *** oxidation performance was examined in a 50 vol%H_(2)O-50 vol%O_(2)environment at 1350℃for up to 300 *** results indicate that a dense ytterbium aluminum garnet(YbAG)layer wasformed after modification,decreasing the porosity by 80%.Due to the elimination of fast diffusion channels and the lowoxygen permeability of YbAG,aluminum modification significantly reduced the growth rate of SiO_(2)-TGO by nearly twoorders of ***,its thickness decreased by more than 70%after 300 h of exposure.A diffusioncontrolled oxidation mechanism indicates that the modified dense surface is equivalent to an initial SiO_(2)layer with a specificthickness,causing a shift in the oxidation time and increasing the oxidation *** research provides valuableinsights for designing Si-based EBC with improved lifetimes.

关键词： environmental barrier coating(EBC) oxidation modification diffusion cracking

Mitigation of Deane and Hamill phenomenon in gallium nitride high-voltage power supply for electric propulsion system application

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High Voltage 2024年第1期9卷 252-265页

作者： Minghai Dong Hui li Shan Yin Kye Yak See Yingzhe Wu Xiong Xin School of Aeronautics&Astronautics University of Electronic Science and Technology of ChinaChengduChina School of Electrical&Electronic Engineering Nanyang Technological UniversitySingaporeSingapore School of Automation Engineering University of Electronic Science and Technology of ChinaChengduChina Innoscience(Shenzhen)Semiconductor Co.Ltd. ShenzhenChina

The step-up resonant converters are widely adopted to provide high voltage in kV-level for electric propulsion system due to their high efficiency,low mass,modularisation,and high-power *** bipolar Cockcroft-Walton voltage multiplier(BiCWVM)is a major circuit that steps up the voltage in the resonant ***,the diode nonlinearity in BiCWVM can introduce self-sustained quasi-periodic oscillations in the voltage and current waveforms,which is commonly known as the Deane and Hamill(DH)*** oscillation can lead to higher magnetic loss and control failure,and it is more likely to present in the gallium nitride-based converter due to the highfrequency *** authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be *** facilitate the investigation,the circuit before the BiCWVM in the converter is derived and modelled as a voltage source v_(m)and a series inductor L_(sy).Also,the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise-linear(PWL)model,with the simplified circuit and PWL model,the relationship between voltage and current under different operating conditions can be determined with *** relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH ***,a hybrid-/full-silicon carbide(SiC)design is proposed to mitigate the DH phenomenon,which is verified experimentally for a 300-kHz,5-W,20-V/1.5-kV GaN-based step-up resonant converter.

关键词： power resonant high

Acousto-optic modulator-based bi-frequency interferometer for quantum technology

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Chinese Optics Letters 2024年第2期22卷 186-191页

作者：李文奇邓琦琦郭学石李小英 College of Precision Instrument and Opto-Electronics Engineering Key Laboratory of Opto-Electronics Information TechnologyMinistry of EducationTianjin UniversityTianjin 300072China

We demonstrate a high-performance acousto-optic modulator-based bi-frequency interferometer,which can realize either beating or beating free interference for a single-photon level quantum *** and optical efficiency of the interferometer are(99.5±0.2)%and(95±1)%,*** phase of the interferometer is actively stabilized by using a dithering phase-locking scheme,where the phase dithering is realized by directly driving the acousto-optic modulators with a specially designed electronic *** further demonstrate applications of the interferometer in quantum technology,including bi-frequency coherent combination,frequency tuning,and optical *** results show the interferometer is a versatile device for multiple quantum technologies.

关键词： bi-frequency interferometer acousto-optic modulator quantum optics quantum manipulation

Understanding the deterrence effect of punishment for marine information security policies non-compliance

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Journal of Ocean Engineering and Science 2024年第1期9卷 9-12页

作者： Xiaolong Wang Changlin Wang Tianyu Yi Wenli li School of Economics and Management Binzhou UniversityBinzhou256600China School of Business Macao University of Science and TechnologyMacao999078China School of Economics and Management Dalian University of TechnologyDalian116024China

In the organizational setting of marine engineering,a significant number of information security incidents have been arised from the employees’failure to comply with the information security policies(ISPs).This may be treated as a principal-agent problem with moral hazard between the employer and the employee for the practical compliance effort of an employee is not observable without high cost-.On the other hand,according to the deterrence theory,the employer and the employee are inherently self-interested *** is worth examining to what extent the employee is self-interested in the marine ISPs compliance ***,it is important to clarify the proper degree of severity of punishment in terms of the deterrent *** this study,a marine ISPs compliance game model has been proposed to evaluate the deterrence effect of punishment on the non-compliance behavior of employee *** is found that in a non-punishment contract,the employee will decline to comply with the marine ISPs;but in a punishment contract,appropriate punishment will lead her to select the marine ISPs compliance effort level expected by the employer,and cause no potential backfire effect.

关键词： Deterrence mechanism Marine engineering Information security policies Non-compliance behavior Principal-agent model with moral hazard Punishment

轧辊磨床测量监控及砂轮平衡系统的修整方法研究

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精密制造与自动化 2024年第1期 61-64页

作者：谢智立上海机床厂有限公司上海200093

砂轮对于磨床来说是磨削过程中重要的组成部分,砂轮磨削前的修整情况直接决定了工件的表面质量以及能否满足工艺要求,实现砂轮恒线速运行是提高磨削效率和工件表面质量的关键。本文涉及一种采用安装在尾架上的测量机构,实时自动测量砂... 详细信息

砂轮对于磨床来说是磨削过程中重要的组成部分,砂轮磨削前的修整情况直接决定了工件的表面质量以及能否满足工艺要求,实现砂轮恒线速运行是提高磨削效率和工件表面质量的关键。本文涉及一种采用安装在尾架上的测量机构,实时自动测量砂轮的装置及砂轮负载监控修整的理念方法,通过改变砂轮转速从而达到恒线速的方式来进行修磨实现被加工面轮廓外形的精度控制。

关键词：恒线速测径装置磨削监控动平衡控制

Potassium isotopic signatures of modern offshore detrital sediments from different climatic regimes and the implications

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Science China Earth Sciences 2024年第2期67卷 405-419页

作者： Jun MU Tianyu CHEN Qian YU Shichao AN Jianfang CHEN Xuefa SHI Weiqiang li State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing210023China Ministry of Education Key Laboratory for Coast and Island Development School of Geography and Ocean ScienceNanjing UniversityNanjing210023China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou310012China Key Laboratory of Marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao266061China

Potassium isotopes are a novel tracer for continental *** K isotope studies on chemical weathering generally targeted weathering profiles under a particular climate region,yet the effects of chemical weathering on K isotopes under different climatic backgrounds remain ***,little is known about the K isotope signatures of modern unconsolidated detrital ***,we report K isotopic data of surficial seafloor sediments from continental shelves along the east coast of China(ECC),as well as those around the tropical Hainan island in the northern South China *** ECC sediments have a relatively narrow distribution ofδ^(41)K(with reference to NIST3141a)values,which range from(-0.40±0.01)‰to(-0.57±0.04)‰,with an average of(-0.51±0.09)‰.By contrast,δ^(41)K values of Hainan offshore sediments display a larger variation,ranging from(-0.28±0.07)‰to(-0.67±0.02)‰.Theδ^(41)K values of Hainan offshore sediments exhibit negative correlations with the chemical index of alteration(CIA),Al/K,Ti/K,and total iron(FeT),which underlines the control of chemical weathering on K isotopic signatures of detritus inputs into *** also measured Mg isotope compositions for the same samples;interestingly,the variability inδ^(26)Mg of the samples is small(~0.24‰)for all ECC and Hainan offshore sediments,andδ^(26)Mg values do not show clear correlations with indexes of chemical *** study demonstrates the link between K isotopic variability of detrital sediments and climatic conditions including rainfall intensity,which indicates that K isotopes of the detrital component of marine sediments could be applied to study Earth’s climate in deep ***δ^(41)K values of the offshore detrital sediments are significantly less variable than those of pelagic marine sediments,highlighting the importance of distinguishing the effects of diagenesis and neoformation of clay minerals from continental weathering in attempts to study deep-time climate-weathering

关键词： Potassium isotopes Magnesium isotopes Chemical weathering Detrital sediments Climatic regimes Mean annual precipitation

Computer-aided diagnosis of Alzheimer’s disease based on structural magnetic resonance imaging

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Chinese Medical Journal 2024年第12期137卷 1483-1485页

作者： Yihang Huang Keyi Shan Yuzi Yan Wan li School of Computer Science and Engineering Beijing Technology and Business UniversityBeijing 100048China

To the Editor:Alzheimer’s disease(AD)is an irreversible chronic neurodegenerative *** initially affects short-term memory,thinking,and *** then severely disrupts the normal lives of patients and their families and may eventually lead to *** cognitive impairment(MCI)is considered an early stage of *** studies have shown that nearly 20%of patients with MCI are at a risk of developing AD within the next four years.[1]Although there is no impressive way to stop the further development of MCI,only a series of procedures can slow ***,timely and accurate intervention is essential to effectively slow the disease progression.

关键词： diagnosis Alzheimer eventually

Optical grade (Gd_(0.95-x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12) ceramics with near-zero optical loss: Effects of Lu^(3+) doping on structural feature, microstructure evolution, and far-red luminescence

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Journal of Advanced Ceramics 2024年第1期13卷 113-123页

作者： zhigang Sun Ji-Guang li Huiyu Qian Yoshio Sakka Tohru SSuzuki Bin Lu School of Materials Science and Chemical Engineering Ningbo UniversityNingbo 315211China Research Center for Electronic and Optical Materials National Institute for Materials ScienceIbaraki 305-0044Japan Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province Ningbo 315211China

A chemical co-precipitation strategy was employed to synthesize a series of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12)(x=0.1−0.95)powder phosphors,followed by vacuum sintering to achieve transparent garnet ceramic *** density functional theory indicated Lu_(3)Al_(5)O_(12) was formed in priority compared with Gd_(3)Al_(5)O_(12) during solid-phase *** high-temperature sintering,the Lu^(3+)substitution for Gd^(3+)suppressed point mass diffusion leading to a smaller grain *** in-line transmittances of bulk specimens with x=0.1,0.3,0.5,0.7,and 0.95 nm were~83.5%,80.1%,68.8%,73.7%,and 82.2%at 710 nm(Eu^(3+)emission center),respectively,among which the sample of x=0.1 exhibited the optical grade with near-zero optical loss in agreement with the defect-free single crystal(~100%of the theoretical transmittance).The resulting particle and ceramic materials both presented characteristic Eu^(3+)emission arising from 5D0→7FJ(J=1−4)transition,where the dominant far-red emission at~710 nm arising from ^(5)D_(0)→^(7)F_(4) transition overlapped with the absorption of phytochrome(PFR).The photoluminescence excitation and photoluminescence intensities of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12) powders and ceramics generally increased at a higher Gd^(3+)/Lu^(3+)***^(3+)dopants delayed the fluorescence lifetime while the bulk samples had shorter lifetime compared to the particle *** transparent(Gd_(0.85)Lu_(0.1)Eu_(0.05))3Al_(5)O_(12) ceramic phosphor exhibited good thermal stability with a high thermal quenching temperature above 533 *** designed ceramic phosphor-converted light-emitting diode had a saturation injection current of 435 mA and a current-dependent color rendering *** importantly,our report marked the developmental stage of transparent ceramic materials towards zero optical loss.

关键词： transparent ceramics garnet phosphors light-emitting diode(LED) optical properties Gibbs free energy

A Brief of Cold Spell Warning Actions of the National Meteorological Center of China Meteorological Administration

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China CDC weekly 2024年第5期6卷 88-91页

作者： Taiyuan Zhang Mengxue Zhang Qiutong li Yu Lan Huafeng Meteorological Media Group of China Meteorological Administration(CMA) BeijingChina National Institute of Environmental Health Chinese Center for Disease Control and PreventionBeijingChina The National Meteorological Center of China Meteorological Administration(CMA) BeijingChina

The“Outline for High-Quality Development of Meteorology(2022-2035)”was published by the State Council of the People’s Republic of China in April 2022(1).This publication highlights the essential role of meteorological disaster warnings,particularly cold spell warnings,in preventing and mitigating *** outline also sets forth stricter expectations for enhancing the overall capacity of society in terms of meteorological disaster preparedness and response.

关键词： disaster meteorological warning