The contact characteristics between cycloidal gear teeth and pinwheel teeth significantly impact the operational performance of cycloidal pinwheel mechanisms.Current research methods tend to rely primarily on theoreti...The contact characteristics between cycloidal gear teeth and pinwheel teeth significantly impact the operational performance of cycloidal pinwheel mechanisms.Current research methods tend to rely primarily on theoretical calculations,with limited use of experimental methods for detecting dynamic contact properties.We propose a novel method for testing the dynamic contact characteristics of cycloidal pinwheel mechanisms.By combining Hertzian contact theory and contact strength theory,we establish a force and meshing stiffness model for the cycloidal and pinwheel gears,and determine the maximum contact stress and variations in pinwheel gear force and meshing stiffness.Based on the principle of photoelasticity,we built a testing platform for the cycloidal pinwheel mechanism to assess its contact characteristics.This platform provides the stress distribution of the cycloidal pinwheel mechanism and allows us to deduce key parameters such as the number of meshing teeth and the meshing interval.This study provides an experimental method for investigating the contact characteristics of cycloidal pinwheel mechanisms.展开更多
The pinwheel pattern as a suitable and advantageous alternative for the loading implementation of the pallet loading problem （PLP） is identified after a survey on the loading pattern. The definitions, elements, cate...The pinwheel pattern as a suitable and advantageous alternative for the loading implementation of the pallet loading problem （PLP） is identified after a survey on the loading pattern. The definitions, elements, categories, generating algorithms of the pinwheel pattern are discussed and a uniform symmetric pinwheel notation is proposed. Based on the forming geometry of a pinwheel, the pinwheel structure is analyzed in terms of the innate box ratio, the box/block orientation and the box number by combinatorial and geometrical methods. A revised data set for the PLP with an area ratio range from 1 to 76 and a box ratio range from 1 to 10 is proposed. All pinwheel instances with this data set are calculated, and box ratio range is obtained for each possible pinwheel pattern, which can be found for all non-prime numbers of boxes. And a high box ratio makes an optimal pinwheel pattern more likely appear. Results identify the impact of the above pinwheel pattern and the box ratio on the pallet loading problem.展开更多
A pair of "pinwheel-like" metal free phthalocyanines, (D)-and (L)-1,8,15,22-tetrakis (2-isopropyl-5-methylcyclohexoxyl)phthalocyanine (1) were isolated for the first time from cyclic tetramerization of (D)-a...A pair of "pinwheel-like" metal free phthalocyanines, (D)-and (L)-1,8,15,22-tetrakis (2-isopropyl-5-methylcyclohexoxyl)phthalocyanine (1) were isolated for the first time from cyclic tetramerization of (D)-and (L)-3- (2-isopropyl-5-methylcyclohexoxyl)-1,2-dicyanobenzene (2), respectively, in refluxing npentanol in the presence of lithium pentanoate followed by treatment with acetic acid. Owing to the steric hindrance of the bulky menthol groups, C4 tetra-a-substituted phthalocyanine 1 is the main phthalocyanine product generated and then could be purified readily by column chromatography. The newly prepared phthalocyanine has been characterized by a series of spectroscopic technique including MALDI-TOF mass, NMR, electronic absorption and IR spectroscopy in addition to elemental analysis. In addition, their electrochemical properties have also been studied by cyclic voltammetry measurement.展开更多
目的红外小目标检测旨在从复杂背景中准确识别和定位弱小红外目标,在海上侦查、军事救援等任务中具有重要的应用前景。然而,受限于红外图像中目标尺寸小、对比度低等因素,当前的检测方法仍难以实现检测精度与误报率之间的平衡。针对上...目的红外小目标检测旨在从复杂背景中准确识别和定位弱小红外目标,在海上侦查、军事救援等任务中具有重要的应用前景。然而,受限于红外图像中目标尺寸小、对比度低等因素,当前的检测方法仍难以实现检测精度与误报率之间的平衡。针对上述问题,提出一种基于选择性注意力的红外小目标检测网络(selective attentionbased network for infrared small target detection,SANet)。方法具体而言,设计了双路径语义感知模块,用于增强网络对弱小目标的感知能力。该模块融合了标准卷积与风车型卷积两种路径,兼顾局部空间一致性与全局上下文感知能力,并进一步引入空间/通道注意力机制以细化特征表达,从而有效提升了目标与背景的可区分性。此外,为克服U-Net中静态跳跃连接在特征融合中的局限性,进一步提出了选择性注意力融合模块。该模块基于空间动态权重机制实现跨尺度特征的自适应融合,能够根据空间显著性选择性增强关键区域,从而提升对真实目标与误报的辨识能力。结果在3个公开基准数据集上的实验结果验证了所提出的SANet在交并比(intersection over union,IoU)、nIoU、P_(d)和F_(a)4个指标上均优于现有先进方法,其中,本文方法的IoU指标在上述基准数据集上比次优方法分别提升1.93%、4.32%和2.21%。结论SANet有效增强了网络对小目标的感知能力、关键特征的表达能力以及背景干扰的抑制能力。源代码可以在https://gitcode.com/m0_61988291/SANet上获取。展开更多
基金Sponsored by Natural Science Foundation of Hebei Province(Grant No.E2019209153)Tangshan Science and Technology Program(Grant No.22130219G).
文摘The contact characteristics between cycloidal gear teeth and pinwheel teeth significantly impact the operational performance of cycloidal pinwheel mechanisms.Current research methods tend to rely primarily on theoretical calculations,with limited use of experimental methods for detecting dynamic contact properties.We propose a novel method for testing the dynamic contact characteristics of cycloidal pinwheel mechanisms.By combining Hertzian contact theory and contact strength theory,we establish a force and meshing stiffness model for the cycloidal and pinwheel gears,and determine the maximum contact stress and variations in pinwheel gear force and meshing stiffness.Based on the principle of photoelasticity,we built a testing platform for the cycloidal pinwheel mechanism to assess its contact characteristics.This platform provides the stress distribution of the cycloidal pinwheel mechanism and allows us to deduce key parameters such as the number of meshing teeth and the meshing interval.This study provides an experimental method for investigating the contact characteristics of cycloidal pinwheel mechanisms.
基金The National Natural Science Foundation of China(No.70571033,70831002)
文摘The pinwheel pattern as a suitable and advantageous alternative for the loading implementation of the pallet loading problem （PLP） is identified after a survey on the loading pattern. The definitions, elements, categories, generating algorithms of the pinwheel pattern are discussed and a uniform symmetric pinwheel notation is proposed. Based on the forming geometry of a pinwheel, the pinwheel structure is analyzed in terms of the innate box ratio, the box/block orientation and the box number by combinatorial and geometrical methods. A revised data set for the PLP with an area ratio range from 1 to 76 and a box ratio range from 1 to 10 is proposed. All pinwheel instances with this data set are calculated, and box ratio range is obtained for each possible pinwheel pattern, which can be found for all non-prime numbers of boxes. And a high box ratio makes an optimal pinwheel pattern more likely appear. Results identify the impact of the above pinwheel pattern and the box ratio on the pallet loading problem.
基金supported by the National Natural Science Foundation of China(Nos. 41771342 and 21607096)Funds of Shandong "Double Tops" Program(No. SYL2017XTTD15)
文摘A pair of "pinwheel-like" metal free phthalocyanines, (D)-and (L)-1,8,15,22-tetrakis (2-isopropyl-5-methylcyclohexoxyl)phthalocyanine (1) were isolated for the first time from cyclic tetramerization of (D)-and (L)-3- (2-isopropyl-5-methylcyclohexoxyl)-1,2-dicyanobenzene (2), respectively, in refluxing npentanol in the presence of lithium pentanoate followed by treatment with acetic acid. Owing to the steric hindrance of the bulky menthol groups, C4 tetra-a-substituted phthalocyanine 1 is the main phthalocyanine product generated and then could be purified readily by column chromatography. The newly prepared phthalocyanine has been characterized by a series of spectroscopic technique including MALDI-TOF mass, NMR, electronic absorption and IR spectroscopy in addition to elemental analysis. In addition, their electrochemical properties have also been studied by cyclic voltammetry measurement.
文摘目的红外小目标检测旨在从复杂背景中准确识别和定位弱小红外目标,在海上侦查、军事救援等任务中具有重要的应用前景。然而,受限于红外图像中目标尺寸小、对比度低等因素,当前的检测方法仍难以实现检测精度与误报率之间的平衡。针对上述问题,提出一种基于选择性注意力的红外小目标检测网络(selective attentionbased network for infrared small target detection,SANet)。方法具体而言,设计了双路径语义感知模块,用于增强网络对弱小目标的感知能力。该模块融合了标准卷积与风车型卷积两种路径,兼顾局部空间一致性与全局上下文感知能力,并进一步引入空间/通道注意力机制以细化特征表达,从而有效提升了目标与背景的可区分性。此外,为克服U-Net中静态跳跃连接在特征融合中的局限性,进一步提出了选择性注意力融合模块。该模块基于空间动态权重机制实现跨尺度特征的自适应融合,能够根据空间显著性选择性增强关键区域,从而提升对真实目标与误报的辨识能力。结果在3个公开基准数据集上的实验结果验证了所提出的SANet在交并比(intersection over union,IoU)、nIoU、P_(d)和F_(a)4个指标上均优于现有先进方法,其中,本文方法的IoU指标在上述基准数据集上比次优方法分别提升1.93%、4.32%和2.21%。结论SANet有效增强了网络对小目标的感知能力、关键特征的表达能力以及背景干扰的抑制能力。源代码可以在https://gitcode.com/m0_61988291/SANet上获取。
