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A Novel Method of Deinterleaving Radar Pulse Sequences Based on a Modified DBSCAN Algorithm 被引量:2
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作者 Abolfazl Dadgarnia Mohammad Taghi Sadeghi 《China Communications》 SCIE CSCD 2023年第2期198-215,共18页
A modified DBSCAN algorithm is presented for deinterleaving of radar pulses in modern EW environments.A main characteristic of the proposed method is that using only time of arrival of pulses,the method can sort the p... A modified DBSCAN algorithm is presented for deinterleaving of radar pulses in modern EW environments.A main characteristic of the proposed method is that using only time of arrival of pulses,the method can sort the pulses efficiently.Other PDW information such as rise time,carrier frequency,pulse width,modulation on pulse,fall time and direction of arrival are not required.To identify the valid PRIs in a set of interleaved pulses,an innovative modification of the DBSCAN algorithm is introduced which is accurate and easy to implement.The proposed method determines valid PRIs more accurately and neglects the spurious ones more efficiently as compared to the classical histogram based algorithms such as SDIF.Furthermore,without specifying any input parameter,the proposed method can deinterleave radar pulses while up to 30%jitter is present in the associated PRI.The accuracy and efficiency of the proposed method are verified by computer simulations and real data results.Experimental simulations are based on different real and operational scenarios where the presence of missing and spurious pulses are also considered.So,the simulation results can be of practical significance. 展开更多
关键词 deinterleavING radar pulse sequences density based clustering pulse descriptor word
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Deinterleaving of radar pulse based on implicit feature
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作者 GUO Qiang TENG Long +2 位作者 WU Xinliang QI Liangang SONG Wenming 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第6期1537-1549,共13页
In the complex countermeasure environment,the pulse description words(PDWs)of the same type of multi-function radar emitters are similar in multiple dimensions.Therefore,it is difficult for conventional methods to dei... In the complex countermeasure environment,the pulse description words(PDWs)of the same type of multi-function radar emitters are similar in multiple dimensions.Therefore,it is difficult for conventional methods to deinterleave such emitters.In order to solve this problem,a pulse deinterleaving method based on implicit features is proposed in this paper.The proposed method introduces long short-term memory(LSTM)neural networks and statistical analysis to mine new features from similar PDW features,that is,the variation law(implicit features)of pulse sequences of different radiation sources over time.The multi-function radar emitter is deinterleaved based on the pulse sequence variation law.Statistical results show that the proposed method not only achieves satisfactory performance,but also has good robustness. 展开更多
关键词 multi-functional radars of the same type pulse deinterleaving pulse amplitude implicit feature long short-term memory(LSTM)neural networks.
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Relationship between Inter Canine Width and Inter Alar Width, Inter Commissural Width, and Inter Canthal Distance: A Pilot Study
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作者 Grevisse Bindele Ndombolo Augustin Mantshumba Milolo +5 位作者 Fidele Nyimi Bushabu Em Kalala Kazadi Pierrot Kumpanya Ntumba Jean Marie Kayembe Bukama Elias Lubadi Tshilumba Jean Paul Sekele Isouradi 《Open Journal of Stomatology》 2024年第6期279-290,共12页
The aim of this study was to determine the relationship between inter canine width (ICW) and inter alar width (IAW), inter commissural width (ICoW), and inter canthal distance (ICaD) in Bantu population. Materials and... The aim of this study was to determine the relationship between inter canine width (ICW) and inter alar width (IAW), inter commissural width (ICoW), and inter canthal distance (ICaD) in Bantu population. Materials and Methods: It was a pilot study included all participants who were aged at least 18 years, without a history of orthodontics treatment from Prosthodontics Department, Faculty of Dental Medicine, University of Kinshasa. The Ethics committee of the National Center of Research for Dental Sciences in DR Congo approved the study protocol (CNRSB 1504.218). The participants medical records were obtained from the interview and dental examination. Nature of the study was explained with participant information sheet, and an informed consent of all participants was obtained. The inclusion criteria were no missing maxillary and mandibular teeth, no diastema, and no anterior restorations, 18 years old before enrollment in the study. The exclusion criteria were inability to meet the above requirements, pregnancy, and refusal to participate in the study. The inter-canine width (ICW), inter alar width (IAW), inter canthal distance (ICaD) and inter-commissural width (ICoW) of each participant were measured with a digital Vernier caliper (Mitutoyo, UK Ltd.,) (0.01 mm) three times and the average value was recorded. The inter canthal distance (ICaD) was measured without applying pressure by bringing the recording parts of the caliper just in contact with the medial angle. The inter alar width (IAW) was marked with a fine marked pencil on the widest outer surface of the alae of the nose on either side or width. Those two points were measured without applying pressure by bringing the recording parts of the caliper just in contact with the outer surface. The participant was told to stop breathing shortly to avoid any change in shape of the nose. The inter-commissural width (ICoW) was determined by measuring the maxillary lip vermilion from commissure to commissure without the application of pressure on the tissue in the relaxed state. The inter-canine width (ICW) was measured indirectly using a dental floss. A dental floss was marked on one end prior to placement in the mouth. Using that point as reference, the dental floss was circumference along the curvature of the anterior dentition such that it passed along the contact point of all the teeth. The distal end of the canine teeth on both sides was then marked on the floss while it was stretched in the patients mouth. Floss was marked on both sides with the marker pencil. The distance between the two proximal contact points was measured and recorded. Data, analysis and validation were performed by the SPSS software (version 22.0, IBM SPSS Statistics, Chicago, IL, USA). Unpaired t-test was used, of Kolmogorov-Smirnov test. Analysis of variance (ANOVA) test was used to test for comparability between socio-demographic characteristics dental measurements. Pearsons correlation coefficients test was calculated to determine the relationship between facial and dental parameters. Significance was set at P 0.01. Results: Of 314 participants enrolled, 202 were included. The age ranged from 18 to 68 years, with a mean age of 40.62 12.99 years. Although the Pearsons correlation coefficients were negative. Ninety-three participants (46%) were men and one hundred and nine (54%) were women. The overall mean age was 40.62 12.99 years. Facial and dental measurements were greater in women than men with significant differences for ICW (p = 0.04). However, no significant difference was seen between men and women for IAW, ICaD and ICoW (p = 0.44, p = 0.23, p = 0.31 respectively). The correlation including Pearsons correlation coefficient and P-values for all participants is not demonstrated. Conclusion: Within the limitations of this study, the results suggest that IAW, ICaD and ICoW cannot be used as a preliminary method for determining the width of the maxillary for anterior teeth for edentulous patients. 展开更多
关键词 RELATIONSHIP inter-Canine Width inter Alar Width inter Canthal Distance inter Commissural Width
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Inter-Row Spacing of PV Power Plant
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作者 Laiqat Ali Khan 《Energy and Power Engineering》 2024年第3期121-129,共9页
When designing a solar power plant, it is much more important to avoid the shadow on the PV Panels. As the shadow falls on the PV Panels;it significantly reduces the generation of required power as planned and designe... When designing a solar power plant, it is much more important to avoid the shadow on the PV Panels. As the shadow falls on the PV Panels;it significantly reduces the generation of required power as planned and designed. This research paper and case study will help a lot to avoid shadow, especially when selecting inter-row spacing between the strings of solar power plants. 展开更多
关键词 inter Row Spacing Shadow Effect on PV Plant Hot Spot Heating
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Long-term and short-term stability characteristics of receiver inter system bias for BDS3/BDS2
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作者 Jingxuan Guo Weiping Jiang +2 位作者 Yan Chen Xincheng Ma Hua Chen 《Geodesy and Geodynamics》 CSCD 2023年第2期143-149,共7页
The study of inter-system bias(ISB)is important for multi-system fusion and the performance of different signal compatibility.In this paper,the stability of ISB at the BDS3/BDS2 receiver end is calculated and analyzed... The study of inter-system bias(ISB)is important for multi-system fusion and the performance of different signal compatibility.In this paper,the stability of ISB at the BDS3/BDS2 receiver end is calculated and analyzed for different time spans(DOY 060~090 in 2021)from a total of 31 MGEX and iGMAS stations.We adopted two estimation strategies,random walk and constant approach,using the precision products of orbit and clock bias provided by WUM,the influence of which on ISB was also analyzed.Our results showed that the ISB value varied little within a day,and the mean of daily ISB standard deviation was only 0.037 m when the observation condition was good.The signal reception was continuous,indicating a high ISB stability for one day.If extending the time series to one month,however,the ISB standard deviation calculated by constant approach,in which a constant ISB is estimated on a daily basis was about 0.1 m,and the results of adjacent days were not continuous,with no apparent pattern.Concerning the random walk approach,the obtained ISB time series also had a jump,and the conclusion was the same as that of the constant strategy.Besides,receiver types showed a strong regularity in ISB numerical situation,and the distribution of ISB values corresponding to the same receiver type was relatively close.Therefore,we conclude that the ISB parameters remain stable in the short term(one day)and less stable in the long-term period.It is recommended that the ISB term should be set as a constant estimate every day in BDS3/BDS2 solutions,regardless of receiver type consistency. 展开更多
关键词 BDS3 BDS2 inter system bias Stability analysis Receiver type
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Tricube Weighted Linear Regression and Interquartile for Cloud Infrastructural Resource Optimization
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作者 Neema George B.K.Anoop Vinodh P.Vijayan 《Computer Systems Science & Engineering》 SCIE EI 2023年第6期2281-2297,共17页
Cloud infrastructural resource optimization is the process of precisely selecting the allocating the correct resources either to a workload or application.When workload execution,accuracy,and cost are accurately stabi... Cloud infrastructural resource optimization is the process of precisely selecting the allocating the correct resources either to a workload or application.When workload execution,accuracy,and cost are accurately stabilized in opposition to the best possible framework in real-time,efficiency is attained.In addition,every workload or application required for the framework is characteristic and these essentials change over time.But,the existing method was failed to ensure the high Quality of Service(QoS).In order to address this issue,a Tricube Weighted Linear Regression-based Inter Quartile(TWLR-IQ)for Cloud Infrastructural Resource Optimization is introduced.A Tricube Weighted Linear Regression is presented in the proposed method to estimate the resources(i.e.,CPU,RAM,and network bandwidth utilization)based on the usage history in each cloud server.Then,Inter Quartile Range is applied to efficiently predict the overload hosts for ensuring a smooth migration.Experimental results show that our proposed method is better than the approach in Cloudsim under various performance metrics.The results clearly showed that the proposed method can reduce the energy consumption and provide a high level of commitment with ensuring the minimum number of Virtual Machine(VM)Migrations as compared to the state-of-the-art methods. 展开更多
关键词 Cloud infrastructure tricube weighted linear regression inter quartile CPU RAM network bandwidth utilization
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莱卡公司再度亮相Intertextile,用“新”诠释创新实力
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《纺织导报》 CAS 2023年第5期12-12,共1页
8月30日,中国国际纺织面料及辅料(秋冬)博览会(Intertextile)正式落下帷幕。作为暌违两年的再度回归,The LYCRA Company(以下简称“莱卡公司”)携众多新品强势亮相,重磅推出LYCRA■ ADAPTIV fiber(莱卡■智合智纤)系列新产品。为了满足... 8月30日,中国国际纺织面料及辅料(秋冬)博览会(Intertextile)正式落下帷幕。作为暌违两年的再度回归,The LYCRA Company(以下简称“莱卡公司”)携众多新品强势亮相,重磅推出LYCRA■ ADAPTIV fiber(莱卡■智合智纤)系列新产品。为了满足市场对耐用服装的需求,提供更具尺码包容性、更高舒适度和更强功能的服装。 展开更多
关键词 创新实力 高舒适度 纺织面料 博览会 inter 包容性
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基于Inter.iamb-Tabu算法的区域滑坡敏感性评价
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作者 尹超 李仲波 +2 位作者 张凯 王绍平 郭兵 《山地学报》 CSCD 北大核心 2023年第4期608-620,共13页
确定滑坡敏感性概率的空间分布,可为滑坡防治政策制定和土地利用规划提供科学依据。由于成灾环境的空间差异和滑坡机理的复杂性,基于不同逻辑架构(物理模型、理论模型等)的滑坡敏感性评价针对特定孕灾环境,无法提前确定最优数学评价模型... 确定滑坡敏感性概率的空间分布,可为滑坡防治政策制定和土地利用规划提供科学依据。由于成灾环境的空间差异和滑坡机理的复杂性,基于不同逻辑架构(物理模型、理论模型等)的滑坡敏感性评价针对特定孕灾环境,无法提前确定最优数学评价模型,而基于深度学习法的、融合多种模型的混合算法能较好地解决这个问题。本文以山东省淄博市博山区为研究区域,基于单因素Logistic回归法筛选了滑坡致灾因子,通过频率比法对致灾因子进行了分级;对4种基于贝叶斯网络的改进算法(MMHC、MMPC-Tabu、Fast.iamb-Tabu、Inter.iamb-Tabu)进行验证,引入错误指数确定了建模效果最佳的算法;计算了博山区774570个栅格的滑坡敏感性概率,绘制了博山区滑坡敏感性分布图;基于GIS的空间叠加和栅格计算器功能,对比了各模型的滑坡敏感性评价结果。研究结果表明:(1)基于Inter.iamb-Tabu开展博山区滑坡敏感性建模时效果最佳。该模型包含10个节点(9个致灾因子节点和1个结局节点)、14条有向边。研究区域可划分为极高敏感区、高敏感区、中敏感区、低敏感区和极低敏感区,分别占总面积的7.30%(49.80km^(2))、16.50%(112.56km^(2))、26.10%(178.05km^(2))、33.20%(226.49km^(2))和16.90%(115.29km^(2)),分别有67处、22处、7处、2处和1处滑坡位于上述敏感区。(2)MMHC、MMPC-Tabu和Fast.iamb-Tabu模型在训练时易舍弃样本中部分因子的特征信息,以达到模型整体精度最优的目的。研究成果可为山东省淄博市博山区滑坡防治提供理论依据,采用的研究方法同样适用于类似地区。 展开更多
关键词 滑坡敏感性评价 致灾因子 贝叶斯网络 inter.iamb-Tabu算法
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Research progress on inter-monthly winter temperature variation in East Asia and climate prediction
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作者 Ke Fan Hongqing Yang Haixia Dai 《Atmospheric and Oceanic Science Letters》 CSCD 2023年第5期8-16,共9页
近年来,东亚冬季气温的月际间变化十分显著,冬季不同月份或不同阶段之间极端冷暖事件的转折或交替频发.由于月际间变化常常被季节平均掩盖,东亚冬季气候预测面临众多的挑战.因此,亟需研究东亚冬季气温月际间变化的特征和机理,明确其可... 近年来,东亚冬季气温的月际间变化十分显著,冬季不同月份或不同阶段之间极端冷暖事件的转折或交替频发.由于月际间变化常常被季节平均掩盖,东亚冬季气候预测面临众多的挑战.因此,亟需研究东亚冬季气温月际间变化的特征和机理,明确其可预测性和预测来源,进而研制考虑月际变化的东亚冬季气温的有效预测方法和预测模型.本文回顾了过去5年对东亚冬季气温月际间变化的主要特征,物理过程,机制,可预测性和预测的研究进展,同时考虑了多个与气温相联系统的变化,包括冬季风,西伯利亚高压,平流层极涡.本文也进一步讨论了未来的研究前景. 展开更多
关键词 月际间转折变化 冬季气温 东亚 冬季风 可预测性
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对有关电能计量若干问题的思考 被引量:1
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作者 赵伟 赵成 +3 位作者 李世松 仝霞 刘坚 李雪城 《电测与仪表》 北大核心 2024年第1期1-7,共7页
文中基于论证和较全面分析,就不同场景下电能计量所关注的截然不同的问题、更好利用大数据去构建电能表检验新方法、动态电能计量研究面临新挑战、关注超谐波电能计量、不宜将电能计量装置与电能表简单划等号,以及测量准确度不同于测量... 文中基于论证和较全面分析,就不同场景下电能计量所关注的截然不同的问题、更好利用大数据去构建电能表检验新方法、动态电能计量研究面临新挑战、关注超谐波电能计量、不宜将电能计量装置与电能表简单划等号,以及测量准确度不同于测量精度等六个问题,阐述了作者的观点和认识,旨在对开展相关研究,以及更清楚理解相关测量方法及概念等起到促进作用。 展开更多
关键词 智能电能表 电能计量 间谐波 超高次谐波 虚拟标准
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基于点云分割网络的雷达信号分选方法
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作者 陈涛 邱宝传 +1 位作者 肖易寒 杨博溢 《电子与信息学报》 EI CAS CSCD 北大核心 2024年第4期1391-1398,共8页
针对现有基于图像分割的端到端雷达信号分选方法存在的像素点重叠与处理效率不高的问题,该文提出一种基于点云分割网络的端到端分选方法。首先将雷达脉冲流的脉冲描述字(PDW)映射为点云;之后利用点云分割网络(PointNet++)对该点云中各... 针对现有基于图像分割的端到端雷达信号分选方法存在的像素点重叠与处理效率不高的问题,该文提出一种基于点云分割网络的端到端分选方法。首先将雷达脉冲流的脉冲描述字(PDW)映射为点云;之后利用点云分割网络(PointNet++)对该点云中各点依据其所属辐射源进行分割;最后将具有相同标签的点聚类形成脉冲集合,分别提取各脉冲集合所包含的辐射源并形成相应的辐射源描述字。仿真结果表明:所提方法能够有效对未知雷达信号进行分选,在脉冲丢失和虚假脉冲干扰的分选环境下也表现出较强的可靠性与稳定性,并且由于采用具有轻量化特点的模型使得该方法的执行效率更高。 展开更多
关键词 电子侦察 信号分选 端到端 脉冲描述字 点云
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籼粳亚种间育性位点分型及籼粳杂交稻育性位点模式研究
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作者 陈明亮 曾细华 +6 位作者 沈雨民 罗世友 胡兰香 熊文涛 熊焕金 吴小燕 肖叶青 《中国水稻科学》 CAS CSCD 北大核心 2024年第4期386-396,共11页
【目的】了解我国籼稻、粳稻材料及籼粳杂交稻组合中亚种间育性位点的分布,建立实现亚种间育性亲和所需遗传位点模式,探索新的籼粳杂交稻组合模式,为亚种间亲和材料改良和籼粳育性亲和分子设计育种打下基础。【方法】通过筛选得到育性... 【目的】了解我国籼稻、粳稻材料及籼粳杂交稻组合中亚种间育性位点的分布,建立实现亚种间育性亲和所需遗传位点模式,探索新的籼粳杂交稻组合模式,为亚种间亲和材料改良和籼粳育性亲和分子设计育种打下基础。【方法】通过筛选得到育性位点的籼粳分型标记对我国水稻材料进行育性位点的籼粳分型检测,挑选部分籼稻、粳稻亲本进行杂交并统计分析F1代花粉育性和结实率。【结果】籼稻和粳稻之间在所有育性位点均存在少量相互渗入。由于籼稻育性位点渗入,粳稻可以分为Ⅰ型(所有位点均为粳型)和Ⅱ型(Sc^(i)、Sd^(i)和Se^(i),上标i代表来自籼稻)。S5不亲和时籼粳杂交稻结实率约为50%,亲和时结实率约为80%。Sa、Sb、Sc或Sd单个位点杂合对于花粉育性影响较小,但Se/pf12/RHS12单个位点杂合时显著降低花粉育性。籼粳杂交稻材料检测结果表明其育性位点的基本模式是S5和部分花粉育性位点纯合/亲和。带有S5^(n)的籼稻两系不育系深08S与粳稻Ⅱ型材料的杂交F_(1)代的花粉育性和结实率正常。【结论】S5是控制雌配子育性的核心位点。影响雄配子育性的位点具有累加效应,其中Se可能是不可缺少的重要位点。S5+Se与Sa、Sb、Sc、Sd任意两个纯合位点可能是实现籼粳亚种间育性亲和的基本遗传位点模式。以广亲和两系籼稻不育系为母本,常规粳稻为父本的“籼不粳恢”籼粳杂交模式是一个可行的亚种间组合模式。 展开更多
关键词 亚种间育性位点 分型 籼粳杂交稻 育性位点模式
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部际信用治理合作备忘录:性质、效力与优化 被引量:1
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作者 李海平 孙媛 《北京航空航天大学学报(社会科学版)》 2024年第3期30-38,共9页
合作备忘录是部际信用合作治理的重要方式。不同于行政规范性文件,合作备忘录既是公法协定中的部际协定,也是一种契约治理形态。合作备忘录遵循契约相对性一般原理,具有相对效力,但这种效力相对性也是相对的。由于科层制特有的权力结构... 合作备忘录是部际信用合作治理的重要方式。不同于行政规范性文件,合作备忘录既是公法协定中的部际协定,也是一种契约治理形态。合作备忘录遵循契约相对性一般原理,具有相对效力,但这种效力相对性也是相对的。由于科层制特有的权力结构与行政服从义务、不完善的信用立法、对个人利益的保护等,合作备忘录的效力溢出至地方公权力主体和相对人。合作备忘录具有补充信用立法、强化行政协助、促进参与式治理等优势,也存在冲击法律体系、违反法律保留原则、规避监督、缺乏合作保障等不足,因而需从合法性、规范性、民主性等方面加以优化。 展开更多
关键词 合作备忘录 部际 契约 相对效力 信用
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北京“新三代家庭”育儿模式下的儿童友好型城市规划策略 被引量:1
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作者 甘霖 邱红 加雨灵 《规划师》 北大核心 2024年第1期10-16,共7页
回溯儿童友好城市的理念起源,借鉴家庭社会学对于当代抚育结构的经典研究见解,认识到建设儿童友好城市不能仅关注儿童个体,而必须以家庭为完整单元,映射到由全龄人群组成的社会生态系统深部。通过面向北京育儿家庭进行大样本问卷调查,... 回溯儿童友好城市的理念起源,借鉴家庭社会学对于当代抚育结构的经典研究见解,认识到建设儿童友好城市不能仅关注儿童个体,而必须以家庭为完整单元,映射到由全龄人群组成的社会生态系统深部。通过面向北京育儿家庭进行大样本问卷调查,提炼当前北京育儿家庭成员之间亲职分配的主流模式,认识到由代际协作育儿纽带联结的“新三代家庭”已经构成了当前北京最典型的家庭育儿模式。这一认知有助于定位超大城市儿童友好政策输出的侧重领域,避免儿童友好城市创建走向千城一面。通过深入挖掘这一典型模式下“双职工中青年”“银发育儿族”“多孩家庭子女”等人群需求,提出6点促进儿童与家人共享城市服务的策略。 展开更多
关键词 儿童友好城市 家庭友好城市 新三代家庭 隔代抚育
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一种针对驻留转换雷达的信号分选算法
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作者 张春杰 青松 +1 位作者 邓志安 刘俞辰 《系统工程与电子技术》 EI CSCD 北大核心 2024年第6期1925-1934,共10页
复杂电磁环境下驻留转换雷达的信号分选是制约电子侦察技术发展的瓶颈,由于其复杂多变的成形规律,信号子周期难以被检测;脉冲重复周期调制类型不明,脉冲序列无法成功提取;提取的多个子周期脉冲序列无法合并为一部雷达信号,造成虚警。针... 复杂电磁环境下驻留转换雷达的信号分选是制约电子侦察技术发展的瓶颈,由于其复杂多变的成形规律,信号子周期难以被检测;脉冲重复周期调制类型不明,脉冲序列无法成功提取;提取的多个子周期脉冲序列无法合并为一部雷达信号,造成虚警。针对以上问题,提出一种针对驻留转换雷达的信号分选算法,利用双门限提高子周期检测概率,通过霍夫变换结合迭代自组织聚类判断信号是否属于驻留转换雷达,改进搜索算法以提取脉冲序列,依据排列熵指标将多脉冲序列合并为一部驻留转换雷达信号。仿真实验结果表明,所提算法在25%脉冲丢失率的复杂电磁环境下,可以将三部驻留转换雷达信号成功分选。 展开更多
关键词 驻留转换 信号分选 霍夫变换 脉冲序列搜索 排列熵
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The Inter-Annual Variability of Rainfall Onset and Its Implication on Crop Planting in Selected East Africa Countries
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作者 Isack Baliyendeza Yonah Philemon Henry King’uza +3 位作者 Ladislaus Benedict Chang’a Mecklina Merchades Babyegeye Henry Fatael Mahoo Agnes Lawrence Kijazi 《American Journal of Climate Change》 2023年第2期268-291,共24页
The inter-annual variability of rainfall onset and crop replanting in East Africa (EA) was assessed using daily estimated rainfall data from climate hazard group infrared precipitation (CHIRPS Ver2.0) and monthly Sea ... The inter-annual variability of rainfall onset and crop replanting in East Africa (EA) was assessed using daily estimated rainfall data from climate hazard group infrared precipitation (CHIRPS Ver2.0) and monthly Sea Surface Temperature (SST) indices [Indian Ocean Dipole (IOD) and El-Ni?o Southern Oscillation (ENSO) at NINO3.4 region] from the National Center for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR). The data covered a period of 40 years from1981 to 2020. The methods of cumulative of daily mean rainfall, percentage of onset date departure (PODD), Mann-Kendall (MK) trend test, student t-test, and correlation were applied in the analysis. The results showed that early onset with dry spell (WDS) consideration frequently occurs in Uganda between the first and second dekads of September, while late rainfall onset WDS occurs in the first and second dekads of December over central and Northern Kenya as well as in the Northeastern highlands, parts of the northern coast and unimodal regions in Tanzania. Rainfall onset with no dry spell (WnDS) portrayed an average of 10 days before the occurrence of true onset WDS, with maximum onset departure days (ODD) above 30 days across the Rift Valley area in Kenya and the Northeastern highlands in Tanzania. The high chance of minimum ODD is seen over entire Uganda and the area around Lake Victoria. However, few regions, such as Nakuru (Kenya) Gulu and Kibale (Uganda), and Gitega (Burundi), revealed a slight positive linear trend while others showed negative trend. Significant positive patterns for correlation between onset WDS and SST indices (IOD and NINO 3.4) were discovered in Northern and Northeastern Kenya, as well as areas along the Indian Ocean (over Tanzania’s Northern Coast). Inter-annual relationship between onset dates WDS and IOD (NINO3.4) indices exhibits a high correlation coefficient r = 0.23 (r = 0.48) in Uganda and r = 0.44 (r = 0.36) in Kenya. On the other hand, a negative correlation was revealed over Burundi and Tanzania (over a unimodal region). A high percentage of PODD was observed, ranging from 40% to 70% over the Rift Valley in Kenya and at the Northeastern highlands in Tanzania. However, a strong PODD above 70% was observed over Tanga and the Northern Pwani Region in Tanzania. These findings will help farmers to understand the appropriate time for crop planting, as well as help other socio-economic activities that strongly depend on rainfall. 展开更多
关键词 inter-Annual Variability Rainfall Onset Crop Planting East Africa
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一起人炭疽事件引发的畜间流行病学调查
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作者 盛敏 阮武营 +2 位作者 马英英 颜新宇 赵胜杰 《中国动物检疫》 CAS 2024年第7期14-16,21,共4页
2023年7月26日,河南省某县卫健委通报马某等3人被确诊为皮肤炭疽,3人系亲属关系,从事牛羊养殖、屠宰、加工和销售工作。为调查疫病传染源、传播途径,降低畜间疫情发生和公共卫生风险,重点对病例关联的某养殖专业合作社马某肉牛养殖场、... 2023年7月26日,河南省某县卫健委通报马某等3人被确诊为皮肤炭疽,3人系亲属关系,从事牛羊养殖、屠宰、加工和销售工作。为调查疫病传染源、传播途径,降低畜间疫情发生和公共卫生风险,重点对病例关联的某养殖专业合作社马某肉牛养殖场、马某牛羊屠宰点和老马本地牛羊肉店开展了紧急流行病学调查。调查发现:病原随省外引进肉牛传入的可能性较小,马某等人通过宰杀带菌肉牛感染,并通过人员或生产资料将病原传入牛场的可能性较大,当前及近一段时间内当地发生人间和畜间炭疽的风险较低,但病原对当地牛羊养殖和公共卫生的潜在风险不容忽视。建议当地加大动物防疫相关政策宣传力度,普及炭疽等人兽共患病防控知识,切实做好炭疽等人兽共患病防控工作,防范疫情再次发生。 展开更多
关键词 炭疽 流行病学调查 畜间
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企业数字化转型促进了资本跨区域流动吗——基于异地并购视角的研究
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作者 刘锴 纳超洪 樊骁 《中南财经政法大学学报》 北大核心 2024年第4期3-16,共14页
加快资本跨区域流动对构建以国内大循环为主体、国内国际双循环相互促进的新发展格局具有重要的战略意义。本文以2008—2022年中国A股上市公司为样本,借助异地并购这一重要的资本跨区域流动形式,考察新发展格局下企业数字化转型对资本... 加快资本跨区域流动对构建以国内大循环为主体、国内国际双循环相互促进的新发展格局具有重要的战略意义。本文以2008—2022年中国A股上市公司为样本,借助异地并购这一重要的资本跨区域流动形式,考察新发展格局下企业数字化转型对资本跨区域流动的影响。研究发现:企业数字化转型通过降低并购交易成本和提高集团管控能力,有效地促进了异地并购决策,尤其对跨省并购决策的促进作用更显著。异质性分析结果表明,当并购企业所在地区市场化程度更高、税负水平更低、数字金融发展水平更高以及目标企业所在地区营商环境更好时,企业数字化转型对异地并购决策的促进作用更强;同时,这一促进作用在民营企业、非高新技术企业以及高管具有金融背景或海外背景的企业中更显著。本研究丰富了数字经济时代资本跨区域流动驱动因素的研究,从异地并购视角提供了企业数字化转型促进资本跨区域流动的微观证据。 展开更多
关键词 数字化转型 资本跨区域流动 异地并购 交易成本 集团管控能力
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森林火灾污染物质释放及其影响研究进展
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作者 王明玉 司莉青 +6 位作者 陈锋 舒立福 赵凤君 田晓瑞 李伟克 李威 李笑笑 《生态学报》 CAS CSCD 北大核心 2024年第12期4933-4944,共12页
森林火灾是大气中气体污染物和颗粒物的重要来源,可对全球气候系统、大气环境以及生态系统产生重要影响,对全球温室气体和含碳颗粒物释放具有重要的贡献,是推动全球气候变化的重要因素。森林火灾释放污染物已成为区域乃至全球范围内重... 森林火灾是大气中气体污染物和颗粒物的重要来源,可对全球气候系统、大气环境以及生态系统产生重要影响,对全球温室气体和含碳颗粒物释放具有重要的贡献,是推动全球气候变化的重要因素。森林火灾释放污染物已成为区域乃至全球范围内重要污染源之一,这些污染物质与辐射、能见度以及温室效应等问题直接相关。准确地描述森林火灾释放的气体和颗粒污染物释放机理、释放总量、时空分布特征、不同尺度的扩散过程模拟,以及对区域大气环境的影响,对于量化森林火灾释放污染物总量及区域影响具有重要意义。基于森林火灾污染物质释放方面的国内外文献,从火灾释放的污染物质对环境的影响、森林火灾释放污染物定量化和传输路径监测的研究方法、污染物质的扩散和运输模型以及跨区域影响等几个方面进行了综述。森林火灾释放的CO、PM_(10)和PM_(2.5)对环境和人的生命安全造成巨大威胁,而且森林火灾释放的污染物质能够随气流长距离传输,不仅对当地的空气造成污染,污染物也能够随着气团进行长距离传输,并在传输过程与当地气溶胶混合,形成跨区域污染。森林火灾释放污染物扩散、传输模拟通过不同模型相互耦合完成,包括可燃物载量估算模型、可燃物消耗和释放模型、污染物扩散传输模型,以及污染物预测和可视化模型等。总结了国内外森林火灾释放污染物质主要研究方法,并展望了今后研究重点:目前我国关于森林火灾释放物质相关的研究尚不足以支撑我国森林火灾温室气体释放、污染物释放等方面的研究,并且我国目前还没有发展出适合于我国的森林火灾污染物释放模型,以及污染物扩散、传输系统。森林火灾排放因子库大多数引用国外研究结果,在一定程度上增加不确定性,缺乏森林火灾对区域大气环境影响的定量化研究。因此,今后我国应加强对森林火灾污染物质释放与影响的研究,尤其是污染物质扩散和传输模型的预测和可视化研究以及排放因子的测量。 展开更多
关键词 森林火灾污染物 大气环境 扩散模型 跨区域污染
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干旱胁迫下油菜素内酯对植物-土壤化学计量特征及内稳性的影响
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作者 李铭怡 王冉 +6 位作者 贾濠基 耿启明 郭士维 王福豪 刘黎明 董文豪 许文年 《草地学报》 CAS CSCD 北大核心 2024年第4期1068-1077,共10页
为探究施用油菜素内酯(Brassinosteroid,BR)对不同干旱条件下植物与土壤的生态化学计量特征及其相互关系,本研究以黄花决明(Cassia glauca Lam.)为研究对象,采用盆栽控水法,设置正常水分、中度胁迫、重度胁迫处理(田间持水量的75%±... 为探究施用油菜素内酯(Brassinosteroid,BR)对不同干旱条件下植物与土壤的生态化学计量特征及其相互关系,本研究以黄花决明(Cassia glauca Lam.)为研究对象,采用盆栽控水法,设置正常水分、中度胁迫、重度胁迫处理(田间持水量的75%±5%,55%±5%,35%±5%)及4种BR浓度处理(0,0.05,0.2和0.5 mg·L^(-1)),在干旱90天后测定株高、生物量和植物、土壤的养分含量及化学计量特征。研究发现:干旱胁迫导致株高、地上和地下生物量降低;随着施用BR浓度的增加,株高、生物量表现为先上升后下降;0.2 mg·L^(-1)BR有利于植物养分含量提升,地上部提升效果更好;干旱区生态修复中黄花决明的生长对N元素的供应需求较大;施用BR有助于提高黄花决明株高和生物量,调节养分分配策略,缓解干旱对植物的不利影响。本研究可为干旱地区的生态修复和植被重建提供新思路与新方法。 展开更多
关键词 生态修复 干旱胁迫 油菜素内酯 化学计量 养分特征 内稳性
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