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Amplification assisted difference frequency generation for efficient mid-infrared conversion based on monolithic tandem lithium niobate superlattice

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Photonics Research 2017年第4期5卷 355-361页

作者： TAO chen hao LIU WEI KONG RONG shu Key Laboratory of Space Active Opto-Electronics Technology Shanghai Institute of Technical Physics Chinese Academy of Sciences

We report the investigation on the performance of an amplification assisted difference frequency generation(AA-DFG) system driven by pulsed pump and continuous-wave primary signal lasers. A monolithic tandem lithium niobate superlattice was employed as the nonlinear crystal with a uniform grating section for the DFG process, followed by a chirp section for the optical parametric amplification process. The impacts of pump pulse shape, primary signal power, input beam diameter, and crystal structure on the pump-to-idler conversion efficiency of the AA-DFG system were comprehensively studied by numerically solving the coupled wave equations. It is concluded that square pump pulse and high primary signal power are beneficial to high pump-to-idler conversion efficiency. In addition, tighter input beam focus and smaller DFG length proportion could redeem the reduction in conversion efficiency resulting from wider acceptance bandwidths for the input lasers. We believe that such systems combining the merits of high stability inherited from cavity-free configuration and high efficiency attributed from the cascaded nonlinear conversion should be of great interest to a wide community,especially when the pulse shaping technique is incorporated.

关键词： DFG Amplification assisted difference frequency generation for efficient mid-infrared conversion based on monolithic tandem lithium niobate superlattice OPO

Spatial distribution and potential poverty-returning factors of former poverty-stricken villages in the Liangshan Mountains,China

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Journal of Mountain Science 2023年第9期20卷 2692-2707页

作者： chen Yang shu Bo chen Yu HU Jin-hao WEI Dong School of Architecture Southwest Jiaotong UniversityChengdu 611756China School of Architecture and Civil Engineering Xihua UniversityChengdu 610039China

Remote mountainous villages are at risk of falling back into poverty,despite having been lifted out of extreme ***,there has been a lack of focus on the factors contributing to povertyreturn in these villages,which making it difficult to understand the risks and their underlying *** study investigates the spatial distribution of 546 key assistance villages(KAVs)in the Liangshan mountainous region,a former poverty-stricken area,using the average nearest neighbor(ANN)and kernel density estimation(KDE)*** regression and geographically weighted regression(GWR)models are then employed to analyze the relationship between the KAVs'economy and potential povertyreturning *** results show that KAVs are primarily located in elevation ranges of 1800-2500 m(31.87%),with slopes of 6°-15°(42.67%)and 2-3 km from the township(28.94%).The distribution of KAVs exhibits distinct spatial clustering,forming four gathering *** factors impact the KAVs'economy positively,including the normalized difference vegetation index(NDVI),built-up area,grassland,and education facilities,while elevation has a negative *** built-up area has the most critical impact on the rural economy,followed by NDVI and ***,education facilities and grassland areas also have significant *** study suggests promoting the Ex-situ Poverty Alleviation Relocation Program(ESPARP)and increasing rural built-up areas,grasslands,and educational facilities as practical measures for preventing poverty return and promoting economic development promotion in remote mountain villages.

关键词： Key assistance villages Rural revitalization Spatial distribution Potential poverty-returning factors Geographically weighted regression

大型劳教所艾滋病羁押人员集中管理实践与探讨

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职业与健康 2011年第17期27卷 2023-2024页

作者：梁自勉陈抒豪曾琪宫艳华广东省佛山市疾病预防控制中心艾滋病防制科 528051

目的对大型劳教所开展艾滋病羁押人员集中管理的现状进行分析,并探讨其如何进一步完善管理的对策。方法从2008年起,广东省将全省司法系统劳教所艾滋病感染者羁押人员大部分集中在佛山市三水区4所省属大型劳教所进行管理。通过一系列规... 详细信息

目的对大型劳教所开展艾滋病羁押人员集中管理的现状进行分析,并探讨其如何进一步完善管理的对策。方法从2008年起,广东省将全省司法系统劳教所艾滋病感染者羁押人员大部分集中在佛山市三水区4所省属大型劳教所进行管理。通过一系列规范管理后,采用国家艾滋病防治督导评估的核心指标对其运作的现状进行评估,并对存在的问题提出对策。结果集中管理工作开展以来,劳教所各项艾滋病管理指标有显著提高。其中,劳教所艾滋病感染者随访率从2007年12月的64.42%上升到2010年12月的98.83%;CD4检测率则从24.04%上升96.44%。但是,仍存在抗病毒治疗滞后,出所后随访管理存在困难以及所内医疗卫生资源配置相对缺乏等问题。结论大型劳教所艾滋病羁押人员集中管理对有效落实羁押人员艾滋病关怀救助政策有良好的效果,但仍需进一步加大投入,完善所内医疗资源配置,制定配套政策,加强与地方卫生部门的合作。

关键词：艾滋病劳教所集中管理

Revealing the atomistic deformation mechanisms of face-centered cubic nanocrystalline metals with atomic-scale mechanical microscopy: A review

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Journal of Materials Science & Technology 2018年第11期34卷 2027-2034页

作者： Duohui Li Xinyu shu Deli Kong hao Zhou Yanhui chen Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology

Nanocrystalline metals have many functional and structural applications due to their excellent mechanical properties compared to their coarse-grained counterparts. The atomic-scale understanding of the deformation mechanisms of nanocrystalline metals is important for designing new materials, novel structures and applications. The review presents recent developments in the methods and techniques for in situ deformation mechanism investigations on face-centered-cubic nanocrystalline metals. In the first part,we will briefly introduce some important techniques that have been used for investigating the deformation behaviors of nanomaterials. Then, the size effects and the plasticity behaviors in nanocrystalline metals are discussed as a basis for comparison with the plasticity in bulk materials. In the last part, we show the atomic-scale and time-resolved dynamic deformation processes of nanocrystalline metals using our in-lab developed deformation device.

关键词： In situ atomic-scale Nanocrystalline Deformation mechanisms Size effect

Establishment of Numerical Wave Flume Based on the Second-Order Wave-Maker Theory

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China Ocean Engineering 2019年第2期33卷 160-171页

作者： ZHANG hao-chen LIU shu-xue LI Jin-xuan WANG Lei State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

With growing computational power, the first-order wave-maker theory has become well established and is widely used for numerical wave flumes. However, existing numerical models based on the first-order wave-maker theory lose accuracy as nonlinear effects become prominent. Because spurious harmonic waves and primary waves have different propagation velocities, waves simulated by using the first-order wave-maker theory have an unstable wave profile. In this paper, a numerical wave flume with a piston-type wave-maker based on the second-order wave-maker theory has been established. Dynamic mesh technique was developed. The boundary treatment for irregular wave simulation was specially dealt with. Comparisons of the free-surface elevations using the first-order and second-order wave-maker theory prove that second-order wave-maker theory can generate stable wave profiles in both the spatial and time domains. Harmonic analysis and spectral analysis were used to prove the superiority of the second-order wave-maker theory from other two aspects. To simulate irregular waves, the numerical flume was improved to solve the problem of the water depth variation due to low-frequency motion of the wave board. In summary, the new numerical flume using the second-order wave-maker theory can guarantee the accuracy of waves by adding an extra motion of the wave board. The boundary treatment method can provide a reference for the improvement of nonlinear numerical flume.

关键词： second-order wave generation nonlinear wave spurious harmonic wave numerical flume

Top slag refining for inclusion composition transform control in tire cord steel

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International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 490-498页

作者： shu-hao chen Min Jiang Xiao-fei He Xin-hua Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing 100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

Controlling conditions for inclusion plasticization were calculated by FactSage, and the steel/slag reaction equilibration time was determined by pre-equilibrium experiments. Laboratory experiments with different top slags were carried out in 90 rain, and industrial tests were performed based on the results of calculation and laboratory experiments. Scanning electron microscopy （SEM） and energy-dispersive spectroscopy （EDS） were used to determine the morphology and composition of inclusions in tire cord steel. It is found that the shape of in- clusions can be controlled well, and the composition of inclusions varies in the industrial test as the following transformation route： MnO-A1EOa-SiO2→CaO-AIEOa-SiO2→MnO-A1203-SiO2. Inclusion plasticization can be achieved by controlling the binary basicity of top slag （CaO/SiO2 by mass） around 1.0 and the （A1203） content in top slag below 10wt%. Under these controlling conditions in the industrial test, almost all of inclusions in the wire rods achieve plastic deformation.

关键词： tire cords ladle metallurgy inclusions plasticity slags refining

An overview of biofuel power generation on policies and finance environment,applied biofuels,device and performance

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Journal of Traffic and Transportation Engineering(English Edition) 2021年第4期8卷 534-553页

作者： Yang Yang Zhilin Tian Yuanfeng Lan shu Wang hao chen School of Automobile Chang'an UniversityXi'an 710064China ETEC Department&MOBI Research Group Vrije Universiteit BrusselBrussel 1050Belgium

The prices of fossil fuels,the gap between energy supply and demand,energy security,environmental issues,and the reduction of greenhouse gas emissions commonly promote the development of biomass power generation in *** to direct biomass combustion power generation and biogas power generation,liquid biofuel power generation has better application *** and finance environment of countries and organizations have promoted the extensive application of biofuel power generation in recent years,especially in *** of internal combustion engine,gas turbine and fuel cell on the stationary power station and mobile generation shows that gas turbine is the main generator-set,the fuel cell is the fastest-growing and future generator-set,while the engine is the first choice in transport and low power generation *** the second,third and fourth generation biofuels,biomethanol,bioethanol,biodiesel and others have been researched and widely used in power *** addition,power generation performance and emissions have been improved to some extent after biofuels *** the future,combined heat and power(CHP)generation and integrated gasification combined cycle(IGCC)is imperative development trends of power generation for higher energy and exergy *** based on the various generating facilities will be the next choice and direction of energy use trends for transport.

关键词： Biofuel Biomass liquid fuel Power generation Emission

The Crystallization and Melting Behaviors of PDLA-b-PBS-b-PDLA Tri-block Copolymers

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Chinese Journal of Polymer Science 2020年第3期38卷 298-310,I0008页

作者： Cong-shu Feng Yun chen Jun Shao Gao Li hao-Qing Hou College of chemistry and chemical engineering Jiangxi Normal UniversityNanchang 330022China Jiangxi Key Laboratory of Organic Chemistry Jiangxi Science and Technology Normal UniversityNanchang 330013China Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are *** both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different *** the PDLA block,its crystallization behaviors are mainly influenced by temperature and block *** crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block *** crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°*** at higher temperature,the crystallization rates increase at first and then decrease with block *** crystallization rates decrease as elevating the crystallization *** melting temperatures of PDLA blocks increase with block lengths and crystallization *** the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA *** crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 *** Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher *** investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.

关键词： Poly(butylenes succinate)(PBS) Poly(D-lactide)(PDLA) Poly(D-lactide)-block-PBS-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA) Crystallization behavior

Prototype-based classifier learning for long-tailed visual recognition

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Science China(Information Sciences) 2022年第6期65卷 62-76页

作者： Xiu-Shen WEI shu-Lin XU hao chen Liang XIAO Yuxin PENG School of Computer Science and Engineering Nanjing University of Science and Technology Key Lab of Intelligent Perception and Systems for High-Dimensional Information of Ministry of Education and Jiangsu Key Lab of Image and Video Understanding for Social Security Wangxuan Institute of Computer Technology Peking University State Key Laboratory of Integrated Services Networks Xidian University

In this paper, we tackle the long-tailed visual recognition problem from the categorical prototype perspective by proposing a prototype-based classifier learning(PCL) method. Specifically, thanks to the generalization ability and robustness, categorical prototypes reveal their advantages of representing the category semantics. Coupled with their class-balance characteristic, categorical prototypes also show potential for handling data imbalance. In our PCL, we propose to generate the categorical classifiers based on the prototypes by performing a learnable mapping function. To further alleviate the impact of imbalance on classifier generation, two kinds of classifier calibration approaches are designed from both prototype-level and example-level aspects. Extensive experiments on five benchmark datasets, including the large-scale iNaturalist, Places-LT,and ImageNet-LT, justify that the proposed PCL can outperform state-of-the-arts. Furthermore, validation experiments can demonstrate the effectiveness of tailored designs in PCL for long-tailed problems.

关键词： long-tailed distribution categorical prototype classifier generation classifier calibration class imbalance

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