基于词序统计组合的中文文本关键词提取技术

为进一步改善关键词提取的效果,提出一种基于词序统计组合的关键词提取方法。通过词序统计、词性标注、停用词过滤、词语组合等步骤,实现短语或组合词的生成和候选关键词的过滤;通过其它特征项的引入,进一步提高最终提取关键词的准确度。实验结果表明,该方法对中文文本的关键词提取具有良好的效果。     

Two-Stage Robust Optimization Under Decision Dependent Uncertainty

In the conventional robust optimization(RO)context, the uncertainty is regarded as residing in a predetermined and fixed uncertainty set. In many applications, however,uncertainties are affected by decisions, making the current RO framework inapplicable. This paper investigates a class of twostage RO problems that involve decision-dependent uncertainties.We introduce a class of polyhedral uncertainty sets whose righthand-side vector has a dependency on the here-and-now decisions and seek to deri...     

Evaluation of stability and functionality of BaCe1–x Inx O3–δelectrolyte in a wider range of indium concentration

The properties of BaCe_1–xIn_xO_3–δ(x=0.05,0.10,0.15,0.20,0.25,0.30,0.35,and 0.40) as proton conducting electrolyte are examined.The dense electrolyte is formed after sintering at 1300℃for 5 h in air.The samples with In content≥25 mol%contain In₂O₃ as a secondary phase.The highest total conductivity is around 5×10^–3 S/cm for BaCe_0.75In_0.25O_3–δ in the wet hydrogen atmosphere at 700℃.After exposure to p...     

卤化橡胶生产中综合替代物天然高活性氧化镁MagPro®150

高活性氧化镁作为挥发性酸的受体及硫化剂、防焦剂和热稳定剂,可用于配制基于卤化橡胶的橡胶混合物.例如,可用于基于氯丁二烯、含氟弹性体、氯化和氯磺化聚乙烯橡胶生产的橡胶制品,如传送带、压力软管、传动带、汽车密封件、电缆护套等,以及用于轮胎中由卤化丁基橡胶生产的气密层产品.     

水平井喷砂射孔填砂压裂工具冲蚀规律

连续管携带的压裂工具串冲蚀十分严重,制约了水平井喷砂射孔填砂压裂工艺作业效率及推广应用.为此,通过观察现场压裂作业后井下工具串的冲蚀形态,确立了工具主要冲蚀区域的结构特征,通过数值模拟对3种易冲蚀结构进行冲蚀机理研究,找出了冲蚀速率的影响因素,提出了压裂工具的优化思路.研究结果表明:压裂工具在环空高速携砂液冲蚀下会在其...     

Improved Cohen?Sutherland algorithm for TGS transmission imaging

Tomographic gamma scanner (TGS), an advanced γ-ray nondestructive analysis technique, can locate and analyze nuclides in radioactive nuclear waste, and TGS can be categorized into two processes:e.g., transmission measurement and emission measurement.Specifically,transmissionmeasurementsprovidethebasisforaccuratemeasurementofnonuniform radionuclide content in TGS scanning. The scan data were obtained using the Monte Carlo tool Geant4 simulation, and 25voxels were divided into five lengths and fiv...     

Bayesian inference of the crust–core transition density via the neutron?star radius and neutron?skin thickness data

In this work, we perform a Bayesian inference of the crust–core transition densityρt of neutron stars based on the neutronstar radius and neutron-skin thickness data using a thermodynamical method. Uniform and Gaussian distributions for the ρ_t prior were adopted in the Bayesian approach. It has a larger probability of having values higher than 0.1 fm^-3 for ρ_t as the uniform prior and neutron-star radius data were used. This was found to be controlled by the curva...     

Branched fibrous amidoxime adsorbent with ultrafast adsorption rate and high amidoxime utilization for uranium extraction from seawater

Direct collection of uranium from low uranium systems via adsorption remains challenging.Fibrous sorbent materials with amidoxime (AO) groups are promising adsorbents for uranium extraction from seawater.However,low AO adsorption group utilization remains an issue.We herein fabricated a branched structure containing AO groups on polypropylene/polyethylene spun-laced nonwoven (PP/PE SNW) fibers using grafting polymerization induced by radiation (RIGP) to improve AO utilization.The chemical struct...     

Hypernuclei as a laboratory to test hyperon–nucleon interactions

<正>Directedflow(v₁)ofthehypernuclei ³_ΛH and ⁴_ΛH have beenobservedinmid-centralAu+Aucollisions at ■atRHIC.Thismeasurementopens upanewpossibilityforstudyinghyperon–nucleon(Y–N)interactionunderfinitepressure.Inaddition,multi-strangenesshypernucleiprovideavenueto probehyperon–nucleon–nucleon(Y–N–N)andeven hyperon–hyperon–nucleon (Y–Y–N) interactions. Hypernucleiareimportantformakingconnectionbetween nuclear collisions and the equation of s...     

Assembly?oriented reliability analysis method for the top?connection structure of a nuclear fuel assembly

The nuclear fuel assembly is the core component of a nuclear reactor. In a pressurized water reactor fuel assembly, the topconnection structure connects the top nozzle to the guide thimble. Its performance reliability is essential for the stability of the nuclear fuel assembly. In this study, an assembly-oriented reliability analysis method for top-connection structures is presented by establishing an assembly-oriented top-connection structure parameter modeling method and a nonlinear contact ga...