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Experiment-based identification of time delays in linear systems

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Acta Mechanica Sinica 2017年第2期33卷 429-439页

作者： Meng-Shi Jin Yi-Qiang Sun han-wen song Jian Xu School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China Shanghai Engineering Center for Microsatellites Shanghai 201210 China

This paper presents an identification approach to time delays in single-degree-of-freedom (SDOF) and multiple-degree-of-freedom (MDOF) systems. In an SDOF system, the impedance function of the delayed system is expressed by the system parameters, the feedback gain, and the time delay. The time delay can be treated as the 'frequency' of the difference between the impedance function of the delayed system and that of the corresponding uncontrolled system. Thus, it can be identified from the Fourier transform of the difference between the two impedance functions. In an MDOF system, the pseudo-impedance functions are defined. The relationships between the time delay and the pseudo-impedance functions of the delayed system and uncontrolled system are deduced. Similarly, the time delay can be identified from the Fourier transform of the difference between the two pseudo-impedance functions. The results of numerical examples and experimental tests show that the identification approach to keeps a relatively high accuracy.

关键词： Time-delay identification Impedance function Feedback controlled system

Time-delay identification for vibration systems with multiple feedback

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Acta Mechanica Sinica 2016年第6期32卷 1138-1148页

作者： Yi-Qiang Sun Meng-Shi Jin han-wen song Jian Xu School of Aerospace Engineering and Applied Mechanics Tongji University

An approach for time-delay identification is proposed in multiple-degree-of-freedom (MDOF) linear systems with multiple feedback. The applicability of the approach is discussed in detail. Based on the characteristics of frequency domain in feedback controlled system with multiple time-delays, this paper proposes a time-delay identification approach, which is based on the pseudo impedance function of reference point. Treating feedback time-delays as the 'frequencies' of the oscillation curve, the time-delays can be obtained from the 'frequencies' of the curve. Numerical simulation is conducted to validate the proposed approach. The application scope of the approach is discussed with regard to different forms of feedback.

关键词： Multiple time-delays Parameter identification Feedback Frequency response functions

聚酰亚胺/二氧化硅杂化薄膜的制备与性能研究

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陕西理工学院学报（自然科学版） 2014年第2期30卷 5-9,29页

作者：韩文松陕西理工学院材料科学与工程学院陕西汉中723003

首先将3-氨丙基三乙氧基硅烷接枝到纳米二氧化硅表面,制得表面含有氨基的改性纳米二氧化硅粒子(A—SiO2)。再将A—SiO2按不同比例与酐封端的聚酰胺酸进行反应,最后经热酰胺化过程,得到一系列聚酰亚胺/二氧化硅杂化膜。采用红外光谱(FT-... 详细信息

首先将3-氨丙基三乙氧基硅烷接枝到纳米二氧化硅表面,制得表面含有氨基的改性纳米二氧化硅粒子(A—SiO2)。再将A—SiO2按不同比例与酐封端的聚酰胺酸进行反应,最后经热酰胺化过程,得到一系列聚酰亚胺/二氧化硅杂化膜。采用红外光谱(FT-IR)、X-射线衍射(XRD)、紫外光谱(UV-vis)、热重分析(TGA)、动态机械热分析仪和扫描电镜(SEM)对合成的聚酰亚胺及其二氧化硅杂化薄膜进行了表征。UV-vis光谱表明,通过向聚酰亚胺薄膜中添加A—SiO2可以改变聚酰亚胺薄膜的透光性。TGA测试结果表明,随着A—SiO2含量的增加,聚酰亚胺/二氧化硅杂化薄膜的热稳定性有所提高。由机械性能测试可知,当A—SiO2掺杂量小于1.5%时,聚酰亚胺/二氧化硅杂化膜的机械性能优于纯聚酰亚胺的机械性能,当A—SiO2的掺杂量大于2.0%时,聚酰亚胺/二氧化硅杂化膜的机械性能比纯聚酰亚胺的机械性能差。SEM分析可知当A—SiO2粒子含量小于1.5%时,其在聚酰亚胺基体中分散均匀,当含量大于2.0%时,体系出现明显团聚现象。

关键词：聚酰亚胺纳米二氧化硅改性聚酰亚胺二氧化硅杂化膜 nano-SiO2

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超支化水性聚氨酯的合成与性能研究

齐鲁工业大学学报 2016年第5期30卷 14-19页

作者：韩文松齐鲁工业大学化学与制药工程学院山东济南250353

以季戊四醇为"核",N,N-二羟乙基-3-胺基丙酸甲酯为支化单体,用逐步聚合的方法合成第三代超支化聚酯;将其引入到水性聚氨酯中,合成超支化水性聚氨酯;对其结构和性能用红外光谱、激光粒度分析仪、动态力学分析、X射线衍射、热重分析等进... 详细信息

以季戊四醇为"核",N,N-二羟乙基-3-胺基丙酸甲酯为支化单体,用逐步聚合的方法合成第三代超支化聚酯;将其引入到水性聚氨酯中,合成超支化水性聚氨酯;对其结构和性能用红外光谱、激光粒度分析仪、动态力学分析、X射线衍射、热重分析等进行表征。结果表明:超支化水性聚氨酯的粒径分布较水性聚氨酯的粒径分布宽;超支化水性聚氨酯和水性聚氨酯都为无定型结构;超支化水性聚氨酯的玻璃化温度在35℃左右,稍高于水性聚氨酯的玻璃化温度;超支化水性聚氨酯的热稳定性和力学性能优于水性聚氨酯。

关键词：水性聚氨酯超支化水性聚氨酯超支化聚酯合成

Potential role of tanycyte-derived neurogenesis in Alzheimer's disease

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Neural Regeneration Research 2025年第6期20卷 1599-1612页

作者： Guibo Qi han Tang Jianian Hu Siying Kang song Qin Department of Anatomy Histologyand EmbryologySchool of Basic Medical SciencesFudan UniversityShanghaiChina State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science Fudan UniversityShanghaiChina

Tanycytes, specialized ependymal cells located in the hypothalamus, play a crucial role in the generation of new neurons that contribute to the neural circuits responsible for regulating the systemic energy balance. The precise coordination of the gene networks controlling neurogenesis in naive and mature tanycytes is essential for maintaining homeostasis in adulthood. However, our understanding of the molecular mechanisms and signaling pathways that govern the proliferation and differentiation of tanycytes into neurons remains limited. This article aims to review the recent advancements in research into the mechanisms and functions of tanycyte-derived neurogenesis. Studies employing lineage-tracing techniques have revealed that the neurogenesis specifically originating from tanycytes in the hypothalamus has a compensatory role in neuronal loss and helps maintain energy homeostasis during metabolic diseases. Intriguingly,metabolic disorders are considered early biomarkers of Alzheimer's disease. Furthermore,the neurogenic potential of tanycytes and the state of newborn neurons derived from tanycytes heavily depend on the maintenance of mild microenvironments, which may be disrupted in Alzheimer's disease due to the impaired blood–brain barrier ***, the specific alterations and regulatory mechanisms governing tanycyte-derived neurogenesis in Alzheimer's disease remain unclear. Accumulating evidence suggests that tanycyte-derived neurogenesis might be impaired in Alzheimer's disease, exacerbating neurodegeneration. Confirming this hypothesis, however, poses a challenge because of the lack of long-term tracing and nucleus-specific analyses of newborn neurons in the hypothalamus of patients with Alzheimer's disease. Further research into the molecular mechanisms underlying tanycyte-derived neurogenesis holds promise for identifying small molecules capable of restoring tanycyte proliferation in neurodegenerative diseases. This line of investigation could pro

关键词： Alzheimer's disease blood–brain barrier ependymoglial cells hypothalamus metabolic diseases neural stem cells neurogenesis neuroinflammatory diseases neurons tanycyte

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空时分组码的联合信道估计和符号检测算法

上海交通大学学报 2004年第2期38卷 207-210,214页

作者：单淑伟罗汉文宋文涛上海交通大学电子信息与电气工程学院上海200030

提出了假设信道仅在p个符号持续时间内(p为空时分组码传输矩阵的行数)是不变的慢衰落条件下,适用于空时分组码发射分集系统的联合信道估计和符号检测的EM(Expectation-Maximization)算法.利用空时分组码的正交结构,该算法保持了空时分... 详细信息

提出了假设信道仅在p个符号持续时间内(p为空时分组码传输矩阵的行数)是不变的慢衰落条件下,适用于空时分组码发射分集系统的联合信道估计和符号检测的EM(Expectation-Maximization)算法.利用空时分组码的正交结构,该算法保持了空时分组码线性译码的优点,具有较低的复杂度和较小的计算量.仿真结果表明,在不同信噪比条件下,该算法可得到较好的误帧率性能.

关键词：空时分组码信道估计符号检测慢衰落

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内燃机轴瓦常用材料性能及选用

内燃机配件 2007年第4期 26-29页

作者：韩文松杭州轴瓦有限公司

本文介绍了内燃机轴瓦材料的性能和使用选配及其影响,并提出来内燃机轴瓦材料的技术的发展方向和环保要求。

关键词：减摩性顺应性耐磨性抗咬粘性强度抗腐蚀嵌入性

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内燃机机油压力低故障原因分析

内燃机 2006年第2期22卷 58-59页

作者：韩文松杭州佳润滑动轴承有限公司浙江杭州310016

机油压力是影响润滑效果的关键指标,机油压力低会导致摩擦副之间油膜不理想,使之产生半干摩擦甚至干摩擦,从而造成运转部件摩擦副的磨损,降低使用寿命,甚至拉伤、咬合毁坏的严重后果。在日常运行中,内燃机中机油压力低报警系统亮“红灯... 详细信息

机油压力是影响润滑效果的关键指标,机油压力低会导致摩擦副之间油膜不理想,使之产生半干摩擦甚至干摩擦,从而造成运转部件摩擦副的磨损,降低使用寿命,甚至拉伤、咬合毁坏的严重后果。在日常运行中,内燃机中机油压力低报警系统亮“红灯”而自动停机的故障较为突出,为了保证内燃机正常工作,就必须维持机油压力在合理的指标内,排除造成机油压力低的原因。

关键词：摩擦副摩滑面摩擦

价值工程在农村污水处理设施比选中的应用研究——以东阳市为例

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价值工程 2017年第2期36卷 43-45页

作者：韩文松浙江广厦建设职业技术学院东阳322100

农村污水处理终端设施,传统的有化粪池、沼气发酵池等,新型的包括埋地式污水处理设施、微动力一体化设备、无动力厌氧处理设备+人工湿地模式等几种,本文主要针对不同的处理设施,采用价值工程原理,结合层次分析方法,从处理能力、效果等... 详细信息

农村污水处理终端设施,传统的有化粪池、沼气发酵池等,新型的包括埋地式污水处理设施、微动力一体化设备、无动力厌氧处理设备+人工湿地模式等几种,本文主要针对不同的处理设施,采用价值工程原理,结合层次分析方法,从处理能力、效果等技术层面及投资、运营维护等经济层面为待建项目提供参考依据。

关键词：农村污水终端设施比选分析