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Micromagnetic simulations on demagnetization processes in anisotropic Nd2Fe14B magnets
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作者 Lei Li Shengzhi Dong +5 位作者 Rui Han Kuikui Song Dong Li Minggang Zhu Wei Li Wei Sun 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第6期628-632,共5页
Individual grains with diverse dimensional parameters were introduced to investigate the magnetization reversals in anisotropic Nd2 Fe14B magnets. The micromagnetic simulations were carried out via Object Oriented Mic... Individual grains with diverse dimensional parameters were introduced to investigate the magnetization reversals in anisotropic Nd2 Fe14B magnets. The micromagnetic simulations were carried out via Object Oriented MicroMagnetic Framework(OOMMF). With the same bottom area and height, analysis results show that the coercive fields for different bottom shapes are of similar values. Designed as a cubic grain,the coercive field presents descending tendency as grain volume ascends. Under constant grain volume,with aspect ratio increasing, the coercive field decreases in the beginning and increases soon. Based on the demagnetization field vector, the effects of bottom shape, grain volume and aspect ratio on the coercive field can be explained. The nucleation point is chosen to discuss. Its synthetic field and reversal field are calculated by parallelogram law and inverse external field equation, respectively. The synthetic field equal to the reversal field is defined as critical field, which always shows the same tendency as the coercive field for all cases of this study. It can be concluded that critical field is qualified to be a reference index to measure the magnitude of coercive field. 展开更多
关键词 MICROMAGNETIC simulation DEMAGNETIZATION FIELD Coercive FIELD SYNTHETIC FIELD CRITICAL FIELD Rare earths
Effects of freeze-thaw cycle and dry-wet alternation on slope stability 预览
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作者 YaLing Chou LiYuan Sun +1 位作者 BaoAn Li XiaoLi Wang 《寒旱区科学:英文版》 CSCD 2019年第2期159-172,共14页
The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freeze-thaw cycle and dry-wet alternation on the shear-strength parameters of the uns... The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freeze-thaw cycle and dry-wet alternation on the shear-strength parameters of the unsaturated loess was investigated by laboratory experimental methods. Moreover, the temperature field, seepage field, and stability of slopes with different gradients were simulated under the effect of the freeze-thaw cycle and dry-wet alternation by using the geotechnical analysis software Geo-Studio. The research results showed (1) when the freeze -thaw cycle was repeated on the slope, with the frozen depth increasing, the melted depth did the same;besides, the closed loop of isotherms formed on the slope;(2) under the action of dry-wet circulation, the negative pore-water pressure and volumetric water content showed an upward tendency. However, owing to the different slope gradients, rainfall infiltration was not the same. As time went by, the differences of the negative pore-water pressure and volumetric water content between the slopes of different gradients continued to increase;(3) with the freeze-thaw cycle and dry-wet alternation increasing, the slope-safety factor decreased. Especially in the early period, the slope-safety factor changed remarkably. For slopes undergoing freeze-thaw action, the slope-safety factor was negatively correlated with the gradient. However, with regard to slopes undergoing dry- wet alternation, the result became more complex because the slope-safety factor was related to both seepage strength and slope grade. Accordingly, further research is needed to study the effect of seepage strength and slope grade on the stability of loess slopes. 展开更多
关键词 FREEZE-THAW action dry-wet ALTERNATION temperature FIELD SEEPAGE FIELD slope stability
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Causes of geothermal fields and characteristics of ground temperature fields in China 预览
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作者 MAO Xiao-ping LI Ke-wen WANG Xin-wei 《地下水科学与工程:英文版》 2019年第1期15-28,共14页
There are many arguments on energy sources and main controlling factors of geothermal fields, so a systematic study on the distribution of ground temperature fields shall be necessary. In this paper the thermal conduc... There are many arguments on energy sources and main controlling factors of geothermal fields, so a systematic study on the distribution of ground temperature fields shall be necessary. In this paper the thermal conduction forward method of geothermal field is used to simulate cooling rate of abnormal heat sources and heat transfer of the paleo-uplift model. Combined with a large number of geothermal field exploration cases and oil exploration well temperature curves of domestic and foreign, the following conclusions are drawn:(1) According to the magmatic activity time, the magmatism activities are divided into two categories: Magma active areas (activity time < 500 000 years) and weak/magma inactive areas (activity time > 500 000 years). The latter has a fast cooling rate (the cooling time of the magma pocket buried around 10 km is less than 200 000 years) after it has intruded into the shallow layer and it has no direct contribution to modern geothermal fields;(2) China belongs to a weak/magma inactive area such as Tengchong region and Qinghai-Tibet region because the chronological data of these regions show that its magma activity time is more than 500 000 years;(3) The temperature of most geothermal fields can be obviously divided into three segments in the vertical direction: A high geothermal gradient segment (Segment H) at the surface, then a low geothermal gradient segment (Segment L) at a secondary depth, and finally a lower temperature segment (Segment D) at a deeper depth. The temperature isoline presents a mirror reflection relation on the temperature profile, indicating that geothermal field is dominated by heat conduction, rather than having an abnormally high temperature “heat source” to provide heat;(4) Near-surface (0-5 km) materials’ lateral heterogeneity caused by tectonic movement shall probably be the main controlling factor of ground temperature fields. 展开更多
关键词 Ground temperature FIELD BASEMENT HEAT flow GEOTHERMAL FIELD MAGMA pocket Coefficient of HEAT conduction Palaeouplifth MAGNETOTELLURIC
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Modeling electric field of power metal-oxide-semiconductor field-effect transistor with dielectric trench based on Schwarz–Christoffel transformation
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作者 汪志刚 廖涛 王亚南 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期366-373,共8页
A power metal-oxide-semiconductor field-effect transistor (MOSFET) with dielectric trench is investigated to enhance the reversed blocking capability.The dielectric trench with a low permittivity to reduce the electri... A power metal-oxide-semiconductor field-effect transistor (MOSFET) with dielectric trench is investigated to enhance the reversed blocking capability.The dielectric trench with a low permittivity to reduce the electric field at reversed blocking state has been studied.To analyze the electric field,the drift region is segmented into four regions,where the conformal mapping method based on Schwarz–Christoffel transformation has been applied.According to the analysis,the improvement in the electric field for using the low permittivity trench is mainly due to the two electric field peaks generated in the drift region around this dielectric trench.The analytical results of the electric field and the potential models are in good agreement with the simulation results. 展开更多
关键词 CONFORMAL mapping Schwarz–Christoffel TRANSFORMATION electric field TRENCH metal-oxidesemiconductor FIELD-EFFECT transistor (MOSFET) breakdown voltage
Optimization of ambipolar current and analog/RF performance for T-shaped tunnel field-effect transistor with gate dielectric spacer
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作者 韩茹 张海潮 +1 位作者 王党辉 李翠 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期656-662,共7页
A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics ... A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics such as current-voltage relationships, energy band diagrams, band-to-band tunneling(BTBT) rate and the magnitude of the electric field are investigated by using TCAD simulation. It is found that compared with conventional TTFET and TTFET with gate-drain overlap(GDO) structure, GDS-TTFET not only has the minimum ambipolar current but also can suppress the ambipolar current under a more extensive bias range. Furthermore, the analog/RF performances of GDS-TTFET are also investigated in terms of transconductance, gate-source capacitance, gate-drain capacitance, cutoff frequency, and gain bandwidth production. By inserting a low-κ spacer layer between the gate electrode and the gate dielectric, the GDS structure can effectively reduce parasitic capacitances between the gate and the source/drain, which leads to better performance in term of cutoff frequency and gain bandwidth production. Finally, the thickness of the gate dielectric spacer is optimized for better ambipolar current suppression and improved analog/RF performance. 展开更多
关键词 tunneling field effect TRANSISTOR T-SHAPED TUNNEL FIELD-EFFECT TRANSISTOR gate dielectric SPACER ambipolar current analog/RF performance
“场域-惯习”视域下的皖北篾器工艺分析 预览
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作者 彭心勤 《景德镇学院学报》 2019年第1期94-98,共5页
皖北篾器工艺是皖北地域一项重要的传统手工技艺。皖北篾器原材料的土壤环境、地理及气候对皖北蔑器器型、材料与工艺特征发展起到本源性的制约作用。以实践社会学的“场域-惯习”的理论为方法论,通过对皖北篾器原材料的生长环境分析,... 皖北篾器工艺是皖北地域一项重要的传统手工技艺。皖北篾器原材料的土壤环境、地理及气候对皖北蔑器器型、材料与工艺特征发展起到本源性的制约作用。以实践社会学的“场域-惯习”的理论为方法论,通过对皖北篾器原材料的生长环境分析,疏导出皖北篾器的地理空间特质,依据皖北篾器的场域特征,将这种地理空间和社会空间结合,可以总结出皖北篾器工艺的场域特征。继而以皖北篾器从业手艺人的惯习为媒介,通过场域和惯习的关系分析,以期对皖北篾器工艺的传承性创新场域的建构做出一个揭示。 展开更多
关键词 皖北篾器工艺 “场域” “惯习” 创新场域
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Validation and reproducibility of the Heidelberg Edge Perimeter in the detection of glaucomatous visual field defects
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作者 Qi N. Cui Priyanka Gogt +5 位作者 Jonathan M. Lam Safa Siraj Lisa A. Hark Jonathan S. Myers L. Jay Katz Michael Waisbourd 《国际眼科杂志:英文版》 SCIE CAS 2019年第4期577-581,共5页
AIM: To validate the ability of the Heidelberg Edge Perimeter (HEP) in detecting glaucomatous visual field (VF) defects compared to the Octopus Visual Field (OVF) Analyzer and to determine the test-retest repeatabilit... AIM: To validate the ability of the Heidelberg Edge Perimeter (HEP) in detecting glaucomatous visual field (VF) defects compared to the Octopus Visual Field (OVF) Analyzer and to determine the test-retest repeatability of both modalities. METHODS: This prospective, cross-sectional study was conducted at Wills Eye Hospital, Philadelphia, PA. Glaucoma subjects and unaffected controls underwent VF testing using HEP standard automated perimetry (SAP) III 30-2 Adaptive Staircase Thresholding Algorithm (ASTA) FAST protocol and OVF G-TOP white-on-white strategy. Testing order was randomized. Pearson’s correlation coefficient was calculated for both mean deviation (MD) and pattern standard deviation/square root of loss of variance (PSD/sLV). Receiver operating characteristic (ROC) curves were used to determine the diagnostic abilities of both modalities. Glaucoma subjects returned for repeat testing and intraclass correlation coefficients (ICCs) were calculated to assess test-retest repeatability. RESULTS: Seventy-nine subjects with glaucoma and 36 unaffected controls were enrolled. HEP and OVF were significantly correlated for both MD (r=-0.84;P<0.01) and PSD/sLV (r=0.79;P<0.01). Areas under the ROC curves (AUCs) were also comparable between HEP and OVF for both MD (0.74 and 0.79, respectively;P=0.26) and PSD/sLV (0.74 and 0.82;P=0.08). ICC was high for both HEP (0.96 for MD, 0.95 for PSD/sLV) and OVF (0.82 and 0.88, respectively). Mean test duration (min) was significantly shorter for OVF (2.63) compared to HEP (5.15;P<0.01). CONCLUSION: HEP and OVF show strong correlation for both MD and PSD/sLV, and have similar validity for detecting glaucoma. The test-retest repeatability is high for both HEP and OVF, however the average testing duration of HEP is significantly longer than that of OVF. 展开更多
关键词 glaucoma HEIDELBERG EDGE PERIMETER standard automated PERIMETRY Octopus VISUAL FIELD Analyzer VISUAL FIELD
Spontaneous magnetic field multipolar structure in toroidal plasmas based on 2D equilibrium
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作者 何柳秀 刘明海 赵双云 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期70-75,共6页
The multipolar magnetic field structure is investigated by the momentum conservation equation with self-c on sistent 3D sheared flows during transition of plasma properties from local paramagnetic to diamagnelic field... The multipolar magnetic field structure is investigated by the momentum conservation equation with self-c on sistent 3D sheared flows during transition of plasma properties from local paramagnetic to diamagnelic fields.Numerical results show that the traditional poloidal magnetic field(Bp)is one part of equilibrium magnetic fields.The non-zero-order quantities are originaled from the higher-order terms of 2D equilibrium treatment based on a Fourier expansion of 0(r,0).The distributions of magnetic field vectors of the order of 1,2,and 3 terms are presented respectively in two.four,and six polar fields with the local vortex structures(spontaneous magnetic conn ection).The excitation mechanisms of the magnetic vortices are the coupling effects of the magnetic fluid structure pattern and the toroidal effects.These results can help us understand the physical mechanism of the in teraction between the external perturbation fields and control tearing modes,as well as the radial plasma flow and magnetic vortices. 展开更多
关键词 magnetic FIELD configuration VORTEX STRUCTURE multipolar FIELD
场域、意境与生命--论宋代园林与诗歌及诗人的关系
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作者 罗燕萍 《内蒙古大学学报:哲学社会科学版》 2019年第3期73-78,共6页
宋代是文人园林发展迅速和密集的时代,因此宋代诗歌与园林的关系更加深化:从空间角度,园林是宋代诗人雅集、诗歌生成的场所,助长诗情,提供诗才,文人化程度高的园林更成为辐射文化因子、促进诗歌生成的文化场域;从审美角度,园林融自然与... 宋代是文人园林发展迅速和密集的时代,因此宋代诗歌与园林的关系更加深化:从空间角度,园林是宋代诗人雅集、诗歌生成的场所,助长诗情,提供诗才,文人化程度高的园林更成为辐射文化因子、促进诗歌生成的文化场域;从审美角度,园林融自然与人工之美于一体,与宋代诗歌意境相通,意象系统互有影响,对宋词和宋诗均产生了特定的影响;从心灵史的角度,园林的文化意蕴从北宋的疏离朝堂到南宋的自我放逐,堪称士大夫心灵止泊与生命复苏的精神家园。 展开更多
关键词 宋代园林 诗歌 场域 意境 生命
Application-Oriented Performance Comparison of 802.11p and LTE-V in a V2V Communication System
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作者 Mengkai Shi Yi Zhang +1 位作者 Danya Yao Chang Lu 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第2期123-133,共11页
In recent years,the Vehicle-to-Vehicle (V2V)communication system has been considered one of the most promising technologies to build a much safer and more efficient transportation system.Both simulation and field test... In recent years,the Vehicle-to-Vehicle (V2V)communication system has been considered one of the most promising technologies to build a much safer and more efficient transportation system.Both simulation and field test have been extensively performed to evaluate the performance of the V2V communication system.However, most of the evaluation methods are communication-based,and although in a transportation environment,lack a V2V application-oriented analysis.In this study,we conducted real-world tests and built an application-oriented evaluation model.The experiments were classified into four scenarios:static,following,face 2 face,and crossing vertically,which almost covered all the V2V communication patterns on the road.Under these scenarios,we conducted experiments and built a probability model to evaluate the performance of 802.11p and LTE-V in safetyrelated applications.Consequently,we found out that improvements are still needed in Non-Line-of-Sight scenarios. 展开更多
关键词 Vehicle-to-Vehicle (V2V)communication CONNECTED VEHICLES performance evaluation INTELLIGENT TRANSPORTATION SYSTEM application-oriented field test
从资本差距到场域隔离:城乡教育的家庭支持差距研究 预览
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作者 金久仁 《教育科学》 CSSCI 北大核心 2019年第1期1-8,共8页
当前,我国城乡教育因支持差距所表现出的不公平问题依然较为突出。城乡教育差距的形成不仅受政府支持的影响,也受到来自家庭对子女教育支持的巨大影响,城乡不同家庭所拥有的资本差距、所寄居的分割场域以及基于不同资本和场域所形成的... 当前,我国城乡教育因支持差距所表现出的不公平问题依然较为突出。城乡教育差距的形成不仅受政府支持的影响,也受到来自家庭对子女教育支持的巨大影响,城乡不同家庭所拥有的资本差距、所寄居的分割场域以及基于不同资本和场域所形成的家庭教育支持行为图式对农村孩子受教育的不利处境进行了系统性编制。解决好因家庭支持差距所造成的城乡教育不公平问题,构建基于资源配置、场域融合、价值公正的"城乡教育一体化"的路径是可能方案。 展开更多
关键词 城乡教育 家庭支持 资本 场域
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Unifying neutron star sub-populations in the supernova fallback accretion model
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作者 Bai-Sheng Liu Xiang-Dong Li 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2019年第3期111-122,共12页
We employ the supernova fallback disk model to simulate the spin evolution of isolated young neutron stars(NSs).We consider the submergence of the NS magnetic fields during the supercritical accretion stage and its su... We employ the supernova fallback disk model to simulate the spin evolution of isolated young neutron stars(NSs).We consider the submergence of the NS magnetic fields during the supercritical accretion stage and its succeeding reemergence.It is shown that the evolution of the spin periods and the magnetic fields in this model is able to account for the relatively weak magnetic fields of central compact objects and the measured braking indices of young pulsars.For a range of initial parameters,evolutionary links can be established among various kinds of NS sub-populations including magnetars,central compact objects and young pulsars.Thus,the diversity of young NSs could be unified in the framework of the supernova fallback accretion model. 展开更多
关键词 accretion accretion disks一stars neutron evolution rotation magnetic field magnetars一pulsars general
我国高校专业硕士研究生双导师制的发展与启示 预览
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作者 杨莉 孙美平 +1 位作者 刘慧慧 罗会明 《中国继续医学教育》 2019年第15期9-11,共3页
近年来,为了满足我国对高级应用型人才日益增长的需求,无论是高校还是各类继续教育机构,都更加注重培养学生的实践和应用能力。其中,专业学位研究生的培养与继续教育的人才培养有许多相似之处。例如,均以培养应用型人才为最终目标,通过... 近年来,为了满足我国对高级应用型人才日益增长的需求,无论是高校还是各类继续教育机构,都更加注重培养学生的实践和应用能力。其中,专业学位研究生的培养与继续教育的人才培养有许多相似之处。例如,均以培养应用型人才为最终目标,通过专业授课和现场实习相结合的方式,由双导师或多方导师联合指导。因此,对高校专业学位研究生双导师制优点与不足的分析,对非学历继续教育中导师制的实施与完善具有一定的启示意义。本文分析了我国高校专业硕士研究生实行双导师制的政策背景,概述双导师制度在人才培养中的实施现状及成绩和不足,总结已有研究对"双导师制度"的改进建议。结合我国目前非学历继续教育中导师制的应用,阐述了高校专业学位研究生双导师制的研究对非学历继续教育导师制的一些启示。 展开更多
关键词 双导师制 专业学位 高校 继续教育 现场 应用型人才培养
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绿道体育中国发展的场域思考 预览
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作者 谢冬兴 邓星华 《南京体育学院学报》 2019年第1期7-19,共13页
我国绿道体育的兴起具有鲜明的时代性,又是自觉践行“建设美丽中国”、“决胜全面建成小康社会”、“在发展中保障和改善民生”、“绿水青山就是金山银山”等《习近平谈治国理政》理念的政府行为与民众行动。基于布迪厄场域理论,将绿道... 我国绿道体育的兴起具有鲜明的时代性,又是自觉践行“建设美丽中国”、“决胜全面建成小康社会”、“在发展中保障和改善民生”、“绿水青山就是金山银山”等《习近平谈治国理政》理念的政府行为与民众行动。基于布迪厄场域理论,将绿道体育场域界定为一个能对位于其中的绿道体育参与个体(家庭)、绿道体育组织(营利与非营利)、绿道体育政府机构等利益相关主体产生作用的公共性物理空间,是各个利益相关主体对各自利益及公共利益表现出一定的分享与主动介入的生态、和谐与共享的社会网络意义空间;具有公共性本质,宣扬生态、和谐与共享的意识形态与思维方式,传承家国传统文化的功能。研究认为:绿道体育场域是一个相对独立的网络空间,有自己的独特运行逻辑与边界。绿道体育场域包含关系要素、空间要素与文化要素。具体而言,关系要素是公共服务关系及其隐含的家国关系;空间要素指的是公共性、圈层分异以及“绿色”特征;文化要素则是形成一个生态、建筑、空间、人文四个文化因子循环交织的耦合模式,促进绿道在提供体育公共服务的同时,建构城市和谐文化。绿道体育场域与中国儒道“仁”、“和”及“天人合一”等哲学观点高度契合。最后,提出城市绿道体育场域升级与发展的2.0模式:(1)形成城市绿道体育的家庭体育“常态”;(2)建构城市绿道体育“健康共同体”;(3)实现城市绿道体育“安全阀”功能。 展开更多
关键词 中国 绿道体育 场域 公共服务 城市绿道体育 空间 资本 惯习
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The influence of irregular seafloor topography on the seismic wave field and migration imaging 预览
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作者 Fuxing Han Kun Wang Jianguo Sun 《海洋学报:英文版》 SCIE CAS CSCD 2019年第3期151-158,共8页
One of the problems experienced in marine geophysical exploration is that the layered features in the migration imaging profile are blurred and the seismic energy reflected is weaker in the middle or lower parts. In t... One of the problems experienced in marine geophysical exploration is that the layered features in the migration imaging profile are blurred and the seismic energy reflected is weaker in the middle or lower parts. In this study we model the seismic wavefield records in the undulating seafloor when there is both a slight change and significant change in seafloor topography to analyze its influence on the seismic reflection data and migration imaging profiles. We compare and analyze the wave field records collected at the same point on the original and modified velocity models, and the cross-bonding resulting migration imaging profiles. The results show that whether the seismic reflection data collection is performed along the direction of the survey line or against the direction of the survey line, slight changes in the seafloor topography have little effect on the wave field records and the migration profile, while significant changes in the seafloor topography have great effect on both the wave field records and migration profile. 展开更多
关键词 SEAFLOOR TOPOGRAPHY SEISMIC wave field SEISMIC REFLECTIONS MIGRATION imaging
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Numerical Investigation of Transient Temperature Distribution during Ti-6Al-4V Selective Laser Melting
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作者 XING Xiaodong ZHOU Qiuyu +2 位作者 WANG Shiyuan WANG Liquan JIANG Fengchun 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期370-377,共8页
The transient temperature field in the powder bed has a crucial effect on the quality of parts fabricated using Selective Laser Melting(SLM). In this study, a finite element model is established regarding the variance... The transient temperature field in the powder bed has a crucial effect on the quality of parts fabricated using Selective Laser Melting(SLM). In this study, a finite element model is established regarding the variance of temperature-dependent thermal properties and transformation latent heat. The temperature distribution and melt pool dimensions of a laser scan track were obtained by varying multiple parameters(layer thickness, laser power and scan speed). The effects of transition of material state and heat source model are also analyzed in this paper. The finite element simulation results show that an increased laser power and/or decreased scan speed results in an elevated maximum temperature of the powder layer and a larger melt pool size. Furthermore, it is found that the maximum temperature is significantly lowered due to the heat diffusion into the previous sintered zone. The heat source model has to be selected properly according to the element size. 展开更多
关键词 Selective Laser MELTING TRANSIENT temperature field process parameters MELT POOL
The levels, sources and reactivity of volatile organic compounds in a typical urban area of Northeast China
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作者 Zhuobiao Ma Chengtang Liu +8 位作者 Chenglong Zhang Pengfei Liu Can Ye Chaoyang Xue Di Zhao Jichen Sun Yiming Du Fahe Chai Yujing Mu 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第5期121-134,共14页
Air concentrations of volatile organic compounds(VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carb... Air concentrations of volatile organic compounds(VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carbonyls were 28.54, 6.30, 5.59 and9.78 ppbv, respectively. Seven sources were identified by the Positive Matrix Factorization model based on the measurement data of VOCs and CO. Vehicle exhaust contributed the most(36.15%) to the total propene-equivalent concentration of the measured VOCs,followed by combustion emission(16.92%), vegetation emission and secondary formation(14.33%), solvent usage(10.59%), petrochemical industry emission(9.89%), petrol evaporation(6.28%), and liquefied petroleum gas(LPG) usage(5.84%). Vehicle exhaust, solvent usage and combustion emission were found to be the top three VOC sources for O3 formation potential, accounting for 34.52%, 16.55% and 11.94%, respectively. The diurnal variation of the total VOCs from each source could be well explained by their emission characteristics,e.g., the two peaks of VOC concentrations from LPG usage were in line with the cooking times for breakfast and lunch. Wind rose plots of the VOCs from each source could reveal the possible distribution of the sources around the monitoring site. The O3 pollution episodes during the measurement period were found to be coincident with the elevation of VOCs, which was mainly due to the air parcel from the southeast direction where petrochemical industry emission was found to be dominant, suggesting that the petrochemical industry emission from the southeast was probably a significant cause of O3 pollution in Shenyang. 展开更多
关键词 VOLATILE organic compounds Source APPORTIONMENT PHOTOCHEMICAL ozone formation Field measurement
一种适用于现场原位校准的双输入激励方法 预览
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作者 梁志国 吕国义 +2 位作者 尹肖 孙浩琳 张大治 《计量学报》 CSCD 北大核心 2019年第1期140-145,共6页
针对现场校准中各种非电物理量激励源实现困难的问题,提出一种双输入激励法,以电信号标准源激励校准传感器后面的数据采集系统。借助于现场物理量值提供单值激励,以现场测量标准校准包含传感器的被校测量系统,并判定传感器的工作正常性... 针对现场校准中各种非电物理量激励源实现困难的问题,提出一种双输入激励法,以电信号标准源激励校准传感器后面的数据采集系统。借助于现场物理量值提供单值激励,以现场测量标准校准包含传感器的被校测量系统,并判定传感器的工作正常性。在其工作正常情况下,以传感器稳定的传递特性模型的平移,表述其现实特性,模型参数来源于以往实验室校准结果,从而以双输入激励法完成全测量系统的现场校准。从铂电阻温度计长达6年的校准结果漂移特性,可以看出该方法具有正确性和可行性。 展开更多
关键词 计量学 计量 原位校准 在线校准 现场
全文增补中
Magnetochemistry and chemical synthesis
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作者 胡林 夏国良 陈乾旺 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期5-16,共12页
High magnetic field is one of the effective tools to control a chemical reaction and materials synthesis. In this review,we summarized the magnetic field effects on chemical reactions, such as reaction pathway, growth... High magnetic field is one of the effective tools to control a chemical reaction and materials synthesis. In this review,we summarized the magnetic field effects on chemical reactions, such as reaction pathway, growth behavior of nanomaterials, product phase, and magnetic domain of materials. The surface spins and activity of catalysts under magnetic fields were also discussed. 展开更多
关键词 MAGNETOCHEMISTRY MAGNETIC FIELD EFFECTS
Preface to the special issue on “Multi-Dimensional Light Field Manipulation: Methods and Applications”
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作者 Jian WANG 《中国光电子学前沿:英文版》 EI CSCD 2019年第1期1-3,共3页
Compared with electrons,there is one distinct feature of photons,known as multiple physical dimensions.Frequency/wavelength,time,complex amplitude and polarization are typical physical dimensions of photons.Very recen... Compared with electrons,there is one distinct feature of photons,known as multiple physical dimensions.Frequency/wavelength,time,complex amplitude and polarization are typical physical dimensions of photons.Very recently,the spatial structure of photons,the only known physical dimension left,has attracted increasing interest in full access of photons worthy of exploration.Manipulating these physical dimensions of photons enables a diversity of light related applications such as trapping,sensing,metrology,microscopy,imaging,quantum information processing and optical communications. 展开更多
关键词 MULTI-DIMENSIONAL Light FIELD MANIPULATION METHODS Applications”
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