Results 31 to 40 of about 8,452 (119)
Guangtongxin yanjiu, 2021 在星间激光通信中，精跟踪单元常采用四象限探测器用于光斑位置定位，定位误差的大小直接影响精跟踪单元的测角精度。为实现微弧度量级的测角精度，文章研究了影响探测器定位误差的各个噪声因素，并根据星间光通信的实际情况进行了简化分析，提出了定位误差的具体计算方法，最后通过具体算例评估了各噪声因素的影响程度。研究结果表明，提高发射功率可以在一定范围内提高接收端信号的信噪比，减小定位误差，进而减小测角误差，提高测角精度。但定位误差并非随发射功率的增大而线性减小，当发射功率增大到一定程度之后，定位误差的减小有限 ...
李树德 +4 more
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Deep quantile regression for growth and maturation reaction norms
Methods in Ecology and Evolution, Volume 17, Issue 1, Page 111-124, January 2026.Abstract Understanding species' growth and maturation responses to anthropogenic and environmental pressures is crucial for tracking demographic shifts, phenotypic change and ensuring population sustainability. Traditional regression methods often focus on modelling the conditional mean of life‐history traits, potentially overlooking heterogeneity in ...
Guankui Liu +4 more
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Ultrasound in Obstetrics &Gynecology, Volume 66, Issue 6, Page 747-753, December 2025.ABSTRACT Objective Ultrasound‐based fetal growth assessment is an essential part of clinical decision‐making in modern obstetric care. This study aimed to evaluate the impact of maternal and fetal characteristics on the accuracy and precision of sonographic fetal weight estimation.
M. Granfors +4 more
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体表光学图像引导技术联合图像引导放疗技术等中心双引导复位在乳腺癌调强放疗中的应用
Zhongshan Daxue xuebao. Yixue kexue ban, 2023 目的探讨体表光学图像引导技术（SGRT）联合图像引导放疗技术（IGRT）在乳腺癌术后放疗中实施等中心双引导复位的可行性，评估新的复位模式相对于传统复位模式的误差精度差异。方法回顾性分析2021年7月13日至2022年10月15日在中山大学肿瘤防治中心ELEKTA infinity加速器放疗的乳腺癌保乳术后患者，按不同复位方式分为模拟机复位组（模拟组）41例和双引导复位组（双引导组）40例。模拟组采用模拟机进行复位，首次用CBCT扫描并记录摆位误差 ...
陈雪梅 +7 more
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Administrative Burdens and Inequities in COBRA Take‐Up
World Medical &Health Policy, Volume 17, Issue 4, Page 658-668, December 2025.ABSTRACT To what extent does COBRA's lack of program visibility and complexity induce inequities in access to this form of health insurance? Though COBRA has long been an important tool for helping workers to avoid “job lock,” precious little scholarship has been devoted to understanding its reach.
Miranda Yaver
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四川大学学报. 自然科学版, 2009 利用EGOPS软件仿真研究了多普勒偏差、多普勒频移、时钟稳定性/单差分、接收机噪声和局部多路径等GRAS误差对GNSS无线电掩星反演大气折射率廓线精度的影响.选择了一个上升掩星事件和一个下降掩星事件进行模拟分析,结果表明:误差最大值大部分出现在平流层顶附近,其中多普勒偏差引起的折射率相对误差最大值接近1%,多普勒频移引起的折射率相对误差最大值小于0.2%,时钟稳定性/单差分引起的折射率相对误差最大值接近0.8%,现实接收机噪声引起的折射率相对误差最大值超过了3 ...
饶若愚, 王也英, 杨楠
doaj
The Political Empowerment of Women and Industrialization in Africa
Politics &Policy, Volume 53, Issue 6, December 2025.ABSTRACT This study examines the effect of political empowerment of women on industrialization in Africa. The results, after controlling for cross‐sectional dependence, show that women's political implication causes industrialization. The fixed effects Driscoll/Kraay standard error and the GMM estimators reveal that women's political empowerment ...
Tii N. Nchofoung +2 more
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Jixie chuandong, 1988 有关圆柱齿轮切向综合误差和径向综合误差测量分析的文献资料已累见不鲜,这些测量方法都是基于被测齿轮与理想精确的测量齿轮测出的误差值。但是,这种理想精确的测量齿轮本身具有一定的制造误差,因而不可避免地会影响到对被测齿轮的正确测量与评定。本文介绍了一种既可借助理想精确的测量齿轮,也可直接用一对被测齿轮相互啮合运转,分别测定出一对共轭齿轮的总误差,再运用分离方法,分解出单个齿轮各自的切向综合误差与径向综合误差的测量方法。据我们所知,目前欧州的许多汽车齿轮制造厂家也使用了齿轮成对检验和进行径向综合误差 ...
许国俊, 王满生, 朱道铭
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基于数据相关性分析的全光纤电流互感器误差状态在线评估方法研究
Gaoya dianqi, 2022 全光纤电流互感器是特高压输电系统中电流测量的关键设备，复杂的物理结构导致其测量误差易受多种因素的影响，稳定性较差。常规的误差检测方法是定期利用标准互感器进行比对测试，无法及时发现误差状态的劣化趋势，且经济性较差。针对这一问题，文中提出了一种基于相关性分析的全光纤电流互感器误差状态评估方法：采集换流站同一测量点下三台全光纤电流互感器的测量数据，在电气物理相关性的约束下，针对全光纤电流互感器的测量数据进行主元分形，将误差评估映射为Q统计量的变化分析。数据分析表明 ...
叶剑涛 +5 more
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RETRACTED: The Growing Tide of Antiscience Sentiment: A Global Concern
World Medical &Health Policy, Volume 17, Issue 3, Page 529-537, September 2025.ABSTRACT The growing tide of antiscience sentiment represents a critical global challenge, with particularly visible manifestations in the United States. This viewpoint examines how the rejection of scientific consensus threatens academic institutions, public health, and technological progress worldwide.
Thorsten Rudroff
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