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1. chinaXiv:202205.00169 [pdf]

图像的视觉感知质量评价新概念 ----单幅图像视觉感知质量评价和独立图像间的视觉感知质量比较

祝锐; 刘玉红; 王体春; 谢正祥
Subjects: Biology >> Biomedical Laboratory Science

直至现在,图像质量评价都没有涉及色彩问题。图像质量评价的文献多是评价图像质量(在压缩、传输等图像处理过程中)的变差(降质)程度。平面图像是一种二维的亮度分布。亮度是图像视觉质量的核心参量,没有亮度就没有图像,也就没有论及图像质量的可能。本文提出了三个层次的图像视觉感知质量评价(VPQA)指标:单幅单参数图像质量评价(SS_IQA),单幅五参数精细图像质量评价(SF_IQA),考虑彩色保真性的增强图像质量评价(CF_IQA)。横向论,可分为单幅的图像质量评价(SIQA),多幅图像质量比较,图像增强中的质量评价等三个方面。图像视觉质量评价是智能最佳化图像增强的不可或缺的工具。

submitted time 2022-05-26 Hits13Downloads6 Comment 0

2. chinaXiv:202205.00168 [pdf]

多级属性Q矩阵的验证与估计

秦春影; 喻晓锋
Subjects: Psychology >> Psychological Measurement

多级属性是将诊断测验中传统的二值(即两种水平,通常定义为0和1)属性定义为多值 (多个水平可以为0,1,…),它不但可以描述学生对于知识属性是否掌握,而且可以描述学生在属性上的掌握程度,这样使得诊断测验能提供给被试更丰富的知识掌握详情。本文将适用于二级属性Q矩阵的统计量 (S 统计量)拓展到多级属性下的Q矩阵验证和估计,在两种常见的条件下,设计了两种估计算法:联合估计算法和在线估计算法。模拟实验结果表明:联合估计算法适用于对专家界定的初始Q矩阵进行验证,当初始Q矩阵中包含较少的错误时,通过联合估计算法有很大可能恢复正确的Q矩阵;在线估计算法适用于对“新项目”进行属性向量和项目参数的在线标定,基于一定数量的“基础项目”,在线估计算法对于新项目的估计也能达到较满意的成功率。实证数据分析则进一步展示了该方法的使用。

submitted time 2022-05-26 Hits83Downloads44 Comment 0

3. chinaXiv:202205.00167 [pdf]

一体化促进联结记忆的作用机制:熟悉性和回想加工

刘泽军; 刘伟
Subjects: Psychology >> Cognitive Psychology

当两个或两个以上项目进行一体化编码时,熟悉性也能够支持联结再认,这一观点已经得到大量研究证据的支持。然而,关于一体化如何影响联结再认和构成联结的单个项目再认仍存在分歧。通过回顾现有研究发现:(1)一体化一致性是调节一体化与联结再认关系的重要因素;(2)认知资源有限和新/旧词语义相关性是影响一体化对项目再认作用的重要因素;(3)一体化的发生机制存在 “项目假说”、“图式假说”以及“精细加工假说”三种可能的理论解释。未来研究不仅需要控制一体化一致性,还可以比较不同一体化方式的作用大小以及探索一体化效应的毕生发展规律。

submitted time 2022-05-26 Hits51Downloads28 Comment 0

4. chinaXiv:202205.00165 [pdf]

Transport mechanism of eroded sediment particles under freeze-thaw and runoff conditions

WANG Tian
Subjects: Geosciences >> Geography

Abstract: Hydraulic erosion associated with seasonal freeze-thaw cycles is one of the most predominant factors, which drives soil stripping and transportation. In this study, indoor simulated meltwater erosion experiments were used to investigate the sorting characteristics and transport mechanism of sediment particles under different freeze-thaw conditions (unfrozen, shallow-thawed, and frozen slopes) and runoff rates (1, 2, and 4 L/min). Results showed that the order of sediment particle contents was silt>sand>clay during erosion process on unfrozen, shallow-thawed, and frozen slopes. Compared with original soils, clay and silt were lost, and sand was deposited. On unfrozen and shallow-thawed slopes, the change of runoff rate had a significant impact on the enrichment of clay, silt, and sand particles. In this study, the sediment particles transported in the form of suspension/saltation were 83.58%–86.54% on unfrozen slopes, 69.24%–84.89% on shallow-thawed slopes, and 83.75%–87.44% on frozen slopes. Moreover, sediment particles smaller than 0.027 mm were preferentially transported. On shallow-thawed slope, relative contribution percentage of suspension/saltation sediment particles gradually increased with the increase in runoff rate, and an opposite trend occurred on unfrozen and frozen slopes. At the same runoff rate, freeze-thaw process had a significant impact on the relative contribution percentage of sediment particle transport via suspension/saltation and rolling during erosion process. The research results provide an improved transport mechanism under freeze-thaw condition for steep loessal slopes.

submitted time 2022-05-25 Cooperative journals:《Journal of Arid Land》 Hits46Downloads22 Comment 0

5. chinaXiv:202205.00166 [pdf]

Wind regimes and associated sand dune types in the hinterland of the Badain Jaran Desert, China

MENG Nan; WANG Nai'ang; ZHAO Liqiang; NIU Zhenmin
Subjects: Geosciences >> Geography

Abstract: Wind controls the formation and development of sand dunes. Therefore, understanding the wind regimes is necessary in sand dune research. In this study, we combined the wind data from 2017 to 2019 at four meteorological stations (Cherigele and Wuertabulage stations in the lake basins, and Yikeri and Sumujilin stations on the top of sand dunes) in the hinterland of the Badain Jaran Desert in China, with high resolution Google Earth images to analyze the correlation between the wind energy environments and dune morphology. The results of data analysis indicated that both the wind direction and sand drift intensity exhibited notable spatial and temporal variations. The highest level of wind activity was observed in spring. Northwesterly and northeasterly winds were the dominant in the Badain Jaran Desert. At the Cherigele, Wuertabulage, and Yikeri stations, the drift potential (DP) was below 200.00 vector units (VU). The wind energy environments in most areas could be classified as low-energy environments. The resultant drift direction differed at different stations and in different seasons, but the overall direction was mainly the southeast. The resultant drift potential (RDP)/DP ratio was greater than 0.30 in most parts of the study area, suggesting that the wind regimes mainly exhibited unimodal or bimodal characteristics. Differences between the thermodynamic properties and the unique landscape settings of lakes and sand dunes could alter the local circulation and intensify the complexity of the wind regimes. The wind regimes were weaker in the lake basins than on the top of sand dunes. Transverse dunes were the most dominant types of sand dunes in the study area, and the wind regimes at most stations were consistent with sand dune types. Wind was thus the main dynamic factor affecting the formation of sand dunes in the Badain Jaran Desert BJD. The results of this study are important for understanding the relationship between the wind regimes and aeolian landforms of the dune field in the deserts.

submitted time 2022-05-25 Cooperative journals:《Journal of Arid Land》 Hits43Downloads23 Comment 0

6. chinaXiv:202205.00164 [pdf]

基于纳米压痕法的富Sn相应力-应变关系的研究

刘志高; 侯斌; 刘天寒; 秦红波
Subjects: Mechanical Engineering >> Machinofacture Technique and Equipment

在电子封装领域中,所用的无铅钎料主要是二元或者三元Sn基共晶或近共晶合金,其基体相为富Sn相。为得到富Sn相的力学性能及应力-应变关系,由纳米压痕试验测试获得了富Sn相的弹性模量与硬度,并得到载荷-位移曲线。采用有限元反演分析的方法确定了富Sn相的特征应力和特征应变,并由量纲函数确定应变强化指数。将特征应力和特征应变强化指数等参数代入幂强化模型中,计算得到富Sn相的屈服强度为31.51 MPa,并最终确定富Sn相的应力-应变关系函数表达式。

submitted time 2022-05-25 Cooperative journals:《桂林电子科技大学学报》 Hits64Downloads28 Comment 0

7. chinaXiv:202205.00163 [pdf]

科技革命、颠覆性技术与智慧农业

胡瑞法; 刘万嘉文
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture

本文首先阐述了科技革命的概念与满足条件,提出并分析了内生及外生农业颠覆性技术及其差异,特别是提出了跨界技术的概念并论证了其对农业科技进步的外生影响。然后分析了作为跨界技术的集大成者——智慧农业技术的特点,智慧农业对传统农业生产技术与生产方式的替代以及智慧农业与农村经济转型的关系。在此基础上讨论了中国智慧农业发展所面临的问题。最后有针对性地提出了促进颠覆性技术创新和智慧农业发展的政策建议,包括加强关键颠覆性核心技术研发、改革现有的农业高等教育体系、推动跨界技术的农业产业化研发以及在高标准农田及规模化养殖场实施智慧农业生产等。

submitted time 2022-05-23 Cooperative journals:《智慧农业(中英文)》 Hits159Downloads82 Comment 0

8. chinaXiv:202205.00143 [pdf]

水葱和香蒲叶经济性状对模拟增温和 CO2浓度倍增的响应

余洪艳; 孙梅; 冯春慧; 许俊萍; 陈弘毅; 刘振亚
Subjects: Biology >> Botany >> Applied botany

气候变化是国际社会共同关注的环境问题,植物对气候变化的响应反映了植物应对气候变化的生长和生存策略。叶经济性状与植物对资源的获取、利用和储存直接相关,并且受到温度条件和?CO2 浓度的显著影响。该文采用人工环境控制系统封顶式生长室研究广布湿地植物水葱(Scirpus validus)和香蒲(Typha orientalis)的叶经济性状对模拟增温(现行环境温度+2 ℃)和?CO2 浓度倍增(增至?850 μmol·mol-1)的响应。结果表明:(1)增温处理下,水葱净光合速率、氮含量和磷含量显著降低,但其胞间?CO2 浓度和比叶重显著增加;CO2 浓度倍增处理下,水葱胞间?CO2 浓度和净光合速率均显著降低,但比叶重显著增加。(2)增温处理下香蒲的比叶重也显著增加,而氮含量和磷含量显著降低;香蒲的光合参数、氮含量和磷含量在?CO2 浓度倍增处理下均显著降低,而比叶重显著增加。(3)除碳含量外,水葱和香蒲的其他经济性状参数包括净光合速率、气孔导度、蒸腾速率、胞间?CO2 浓度、氮含量、磷含量和比叶重均在响应增温和?CO2 浓度升高过程中均发挥重要作用。总体而言,该研究结果反映了水葱和香蒲在功能性状上对增温和?CO2 浓度升高的响应策略。两种植物的光合能力和养分含量在两种处理下均受到显著的抑制作用,而其抗逆能力升高,表明增温和?CO2浓度升高不利于水葱和香蒲的生长。

submitted time 2022-05-21 Cooperative journals:《广西植物》 Hits188Downloads109 Comment 0

9. chinaXiv:202205.00144 [pdf]

基于叶绿体基因组SNP的天台鹅耳枥谱系结构与分化分析

陈模舜; 杨仲毅
Subjects: Biology >> Botany >> Applied botany

天台鹅耳枥为中国特有的濒危植物,仅间断分布于浙江省境内,种群数量稀少,已处于极危状态。该文通过对6个自然居群(包含所有居群的母株)cpDNA单核苷酸多态性(SNP)研究,探讨天台鹅耳枥谱系结构与系统分化,以评估濒危状况,并提出相应的保护策略。使用TIANGEN试剂盒法提取基因组DNA,用Illumina novaseq 6000进行高通量测序,对获得叶绿体全基因组序列,使用在线程序OGDRAW制作叶绿体基因组图谱,用DnaSP分析核苷酸多样性,用PopART软件进行单倍型网络构建,使用RAxML软件构建ML tree,用MrBayes构建Bayes tree。结果表明:(1)通过天台鹅耳枥叶绿体全基因组序列分析,大多数蛋白质编码基因和氨基酸序列显示出明显的密码子偏好,检测到cp LTR正向重复为32个,回文重复为25个,反转重复为22个;SSR重复序列不同类型为87个,其中大多数富含A / T,单核苷酸的数量最多。(2)在叶绿体基因组中鉴定了314个单核苷酸多态性,单核苷酸取代显示天台鹅耳枥群体属单系,分为天台县居群(THS)和景宁县居群(JST),居群单倍型之间演化关系呈现星状中心辐射。(3)所有居群核苷酸多样性的变异均较低(Pi<0.005),JST居群和THS居群单倍型多样性较低(Hd为0.5~0.6),显示出天台鹅耳枥在历史上遇到瓶颈后曾发生局部扩张,居群间呈现较大的遗传分化,居群内具有较低的遗传变异与居群间较高的分化水平。通过对叶绿体基因组SNP的研究,揭示天台鹅耳枥的遗传多样性和谱系分化,为濒危植物天台鹅耳枥种质资源保护和遗传拯救提供理论依据。

submitted time 2022-05-21 Cooperative journals:《广西植物》 Hits203Downloads115 Comment 0

10. chinaXiv:202205.00145 [pdf]

吊罗山热带天然林物种多样性的海拔分布格局

李晨笛; 梁宜文; 杨小波; 李东海
Subjects: Biology >> Botany >> Applied botany

海拔梯度是影响物种多样性格局的关键因素。为探究吊罗山热带天然林物种多样性的海拔分布格局,对吊罗山245~1 130 m海拔内的6个热带天然林样地进行植被调查,从群落物种组成、物种多样性、区系组成和叶性质等方面分析沿海拔梯度吊罗山热带天然林物种多样性与群落特征变化规律。结果表明:(1)随海拔升高、温度降低、湿度升高、人为干扰减少,吊罗山热带天然林物种组成以及Margalef、Shannon-Wiener、Simpson、Pielou多样性指数均呈现出先升高后降低的格局;中海拔群落水热条件最为适宜、人为干扰适中、α物种多样性最高。(2)随海拔升高,优势种重要值占比呈现出先降低后升高的格局,且优势种具有明显的更替现象,中海拔群落呈现出低地雨林与山地雨林的过渡性质。(3)群落间S?rensen群落相似度和海拔高度差呈显著负相关(P<0.05)。(4)区系组成以热带区分布为绝对优势,并以热带亚洲(印度-马来西亚)分布为主;热带区分布比例和海拔呈极显著负相关(P<0.01),温带区分布比例和海拔呈极显著正相关(P<0.01)。(5)叶性质呈现出以中型叶、单叶、革质叶、全缘叶为主的热带地区显著特点;小型叶、单叶比例和海拔呈极显著正相关(P<0.01),革质叶、非全缘叶比例和海拔相关性不显著(P>0.05)。综上所述,吊罗山低海拔群落水热条件和人为干扰程度都与高海拔群落存在较大差异,从而导致了物种分布和群落特征的差异性,体现出热带植物与其生境条件相适应的特点。

submitted time 2022-05-21 Cooperative journals:《广西植物》 Hits196Downloads114 Comment 0

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