Results 11 to 20 of about 4,580 (139)
Research on image recognition of cracked eggs based on convolutional neural network model [PDF]
, 2023 Objective: In order to improve the accuracy and operating efficiency of the egg crack detection method based on computer vision. Methods: Used poultry egg simulation impact equipment to obtain cracked eggs, and collected images of cracked eggs and intact
LI Shu, SUN Ke, TANG Mengdi, TONG Siyuan
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A Method Study on Determination of Sediment Content in Water Samples Based on Self-made Differential Pressure Device [PDF]
, 2022 [Objective] The method for quickly and accurately measuring sediment concentrations in water samples in the field based on differential pressure was studied.
Chen Lin +5 more
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, 2018 挠曲电效应是一种新兴的机电耦合效应,在微纳米尺度的传感器、致动器和俘能器方面有广阔的应用前景.本文基于挠曲电材料的变分原理和电吉布斯自由能,推导了表面覆盖电极的挠曲电悬臂梁在电学开路条件下的机电耦合动力学控制方程和相应的力电边界条件.进一步获得了求解电学开路条件下挠曲电悬臂梁自振频率的超越方程.以聚偏氟乙烯(PVDF)材料为算例,讨论了挠曲电系数、末端质量块和梁尺寸对结构自振频率和电学开路/短路条件下结构自振频率有效频移的影响.计算结果表明,挠曲电系数的增大会提高梁的自振频率 ...
周志东 +3 more
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Gaoya dianqi, 2023 基于铁心本体的振动信号更能准确反映铁心状态，针对典型的电力变压器铁心结构，利用测振仪及声学成像系统对一台三相三柱式铁心模型开展振动及分布特性研究。实验结果表明：铁心振动以100 Hz为基频，包含整数倍高次倍频分量。铁心不同方向不同位置振动差异较大，硅钢片平面法向振动强于平面内振动。铁心B柱振动大于A、C柱，铁心柱与上下铁轭接缝处振动较大，沿铁心柱及上下铁轭振动呈近似“U”型分布，且电压越大，趋势越明显。铁心辐射声场云图及声像图均表明铁心B柱与上下铁轭接缝处的辐射噪声贡献远大于其他位置 ...
纪炜 +4 more
doaj
Developmental Medicine &Child Neurology, Volume 61, Issue 3, Page E1-E35, March 2019., 2019 目的 本国际临床指南由欧洲残疾儿童学会（the European Academy of Childhood Disability，EACD）牵头制定，旨在解决发育性协调障碍（developmental coordination disorder，DCD）的定义、诊断、评估、干预以及与社会心理方面的临床应用关键问题。 方法 本指南针对五个领域的关键问题，通过文献综述和专家团队的正式讨论达成共识。为保证指南的循证基础，以“机制”、“评估”和“干预”为检索词, 对2012年更新以来提出的最新建议以及新增的“社会心理问题”和“青少年/成人”为检索词进行检索。根据牛津大学循证医学中心证据等级 (证据水平 [level of evidence, LOE]1–4) 将结果进行分类，最终转化为指南建议。并由国际 ...
Jing Hua +6 more
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Defects of Gamma Oscillations in Auditory Steady‐State Evoked Potential of Schizophrenia
General Psychiatry, Volume 30, Issue 1, Page 27-38, July 2018., 2018 Background Patients with schizophrenia have many cognitive deficits. Gamma oscillations exist in the human brain and are closely related to neurocognition. Auditory Steady‐State Responses (ASSRs) is an electroneurophysiological index that could reflect gamma oscillations.
Chenhui Sun +7 more
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基于镜像磁场和动力学模型的变压器负载振动噪声数字孪生模型研究
Gaoya dianqi, 2022 负载电流引起的绕组振动是运行中变压器噪声的主要来源之一。为了深入研究变压器绕组的负载振动特性，文中首先提出了基于镜像法的绕组漏磁场和绕组电动力计算模型，然后建立了绕组轴向振动的动力学模型，结合电动力计算了绕组振动特性，最后建立了绕组声辐射的有限元模型分析了绕组的声场分布。对一台50 kVA变压器的计算结果表明，镜像法计算的绕组电动力与有限元法的误差小于5%，额定电流下绕组的振动加速度约为0.065 m/s2，绕组辐射噪声最大达到43 dB。文中提出的模型可支撑变压器振动噪声数字孪生技术的研究及应用。
罗兵 +5 more
doaj
Gaoya dianqi, 2023 文章提出了基于合闸振动信号的变压器振动固有频率识别方法，可以据此来实现对变压器机械状态的评估。首先，文章建立了变压器多自由度非线性轴向振动模型，通过计算得出变压器在发生故障时其固有频率将会发生变化，而振动固有频率可以从变压器的合闸振动信号中提取得到，基于此文章提出了基于变分模态分解和特征系统实现算法结合的变压器固有频率识别方法，并根据固有模态分量的统计特性，提出了基于延时峭度法的模态识别方法，最后通过仿真与实验证明所提方法较传统方法而言可以有效的降低谐波模态的干扰，提高固有频率的识别精度。
马宏忠 +6 more
doaj
Functional Ecology, EarlyView.Read the free Plain Language Summary for this article on the Journal blog. Abstract The nested subset pattern (nestedness) has been widely used to explain species distributions in island and fragmented systems. Mountain sky islands serve as critical natural laboratories for understanding the evolutionary consequences of geographic isolation and climate
Caiwen Zhang +5 more
wiley +1 more source
Journal of Advances in Modeling Earth Systems, Volume 17, Issue 9, September 2025.Abstract Rapid‐update data assimilation (DA) cycles, particularly during the early stages of the assimilation process, often suffer from physical imbalances that degrade the quality of analyses and lead to a rapid decline in forecast skill. This study evaluates the impact of combining the incremental analysis update (IAU) method with the ensemble ...
Zhaoyang Huo +6 more
wiley +1 more source