共查询到20条相似文献，搜索用时 78 毫秒
1.
This paper proposes a distributed second-order consensus time synchronization, which incorporates the second-order consensus algorithm into wireless sensor networks. Since local clocks may have different skews and offsets, the algorithm is designed to include offset compensation and skew compensation. The local clocks are not directly modified, thus the virtual clocks are built according to the local clocks via the compensation parameters. Each node achieves a virtual consensus clock by periodically updated compensation parameters. Finally, the effectiveness of the proposed algorithm is verified through a number of simulations in a mesh network. It is proved that the proposed algorithm has the advantage of being distributed, asymptotic convergence, and robust to new node joining. 相似文献
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在锶原子光晶格钟中,黑体辐射频移对系统的频率不确定度影响最为显著。本文从两个方面提出改善这一问题的方案:一方面利用DC Stark效应精确测量原子的静态极化率差;另一方面,将钙光钟与锶光钟的钟跃迁频率进行综合考量,构建出一个不含有黑体辐射频移的参考频率作为频率标准,锶光钟系统的相对不确定度可望控制在2.97×10-17以内。 相似文献
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A clock synchronization method based on IEEE 1588 and its implementation on Ethernet 总被引：1，自引：0，他引：1
We presented a clock synchronization method that contained a clock adjusting algorithm and a frequency compensated clock to achieve precise synchronization among distributed clocks based on IEEE 1588 protocol. Further, we presented its application on Ethernet and implementation of the frequency compensated clock in a field programmable gate array （FPGA） as experiments. The results indicate that this method can support sub-microsecond synchronization with inexpensive standard crystal oscillators. 相似文献
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详细讨论了狭义相对论里面两个极具启发性的问题,即观看运动的时钟和从小角度观看高速运动物体.说明了前者与狭义相对论中通常所说的"时间膨胀"之间的区别与联系,给出了运动时钟和静止时钟的时间间隔之间的关系.对后者,修正了前人讨论中的一处疏漏,从而说明在狭义相对论中涉及观看某现象时如何考虑光信号的传输限制. 相似文献
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Wheeler-Scruggs K 《American annals of the deaf》2002,147(4):11-17
There is much variation in functional level among people who are deaf and low functioning. The present study focused on the work and independent living status of people who are deaf and have varying levels of low functioning. Each study participant attended a comprehensive rehabilitation facility. Information was collected through personal interviews. Not all interviewees were employed at the time of the interview, but the majority lived on their own. Those interviewees who worked were, on the whole, happy with their jobs. Workplace accommodations were virtually nonexistent, while home accommodations included television closed captioning, TTYs, and alarm clocks with visual or vibrating signals. Suggestions and guidelines are given on areas in which people who are deaf and low functioning may need services beyond job placement. 相似文献
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生物测时是昆虫的基本生理功能。昆虫测时功能及作用机制的研究是时间生物学前沿研究内容之一。光感应型昆虫生物钟光信号由眼、脑－眼两种感知类型,驱动部位也有视叶边缘腹侧部分的细胞体和脑两类;遗传控制基因是ｐｅｒ,不同突变体ｐｅｒＤＮＡ之间仅有１个碱基的差异。家蚕卵内的酯酶Ａ４（ＥＡ４）是一种时间间隔测定酶,感知低温、盐酸刺激等信息,启动倒计时型滞育生物钟光ＥＡ４的测时功能与自身的结构有关,受蚕卵内的多肽 相似文献
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Circadian (circa = about; dian = day) rhythms are amongst the most widely studied rhythmic behaviors across a wide range of organisms. Clocks driving circadian rhythms are termed circadian clocks and involve a network of functionally conserved genetic elements that mediate various oscillatory, physiological and behavioral phenomena and help tune the organism to remain in-sync with the external world. While some of the characteristic functional properties of circadian rhythms and clocks driving such rhythms have been studied for a long time now, our knowledge of the molecular and genetic architecture of circadian clocks remained elusive until recent years. This is the second article in a series on circadian rhythms and will introduce you to the molecular cogs and wheels of circadian clocks. 相似文献
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在锶原子光晶格钟中,黑体辐射效应对光钟的频率不确定度影响最为显著。利用表面等离激元晶体的滤波特性,屏蔽大部分黑体辐射能量,可以显著减少相应频移量及其涨落。通过对设计器件透射谱的分析可以测算,经滤波后的黑体辐射剩余能量约为初始能量的4.8%,则锶光钟的黑体辐射频移可减小至112.6mHz,相应不确定度约为3.6×10-18。 相似文献
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运用人体生物钟节律把握教育时机 总被引：5，自引：0，他引：5
对于人体生物钟的研究已经有一个世纪了。虽然人们对于它的评价褒贬不一，在争论中也有人说它是伪科学，但人体生物钟节律理论在人们的日常生活和产生中起着重要作用，应用广泛。而它应用于教与学的研究目前尚少。教师和学生了解并运用自身的生物钟规律，有利于把握教与学的时机，提高教学的效率。 相似文献
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从自然的生物钟现象入手,根据生物钟的类型与意义,讨论了全球变化对生物钟的影响以及人为改变生物钟的后果,提出了本着人与自然和谐发展的原则,人类应遵循自然规律、维持生物钟的观点。 相似文献
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脑电波自组织生物钟极限环及其心理学意义 总被引：2，自引：0，他引：2
吴忆峰 《深圳信息职业技术学院学报》1997,(2)
EQ已成为世界性热门话题。但情绪自我控制和自我激励的理论尚处实证阶段。本文作者采用与化学振荡类比的方法,首次导得描述脑电快、慢波振幅周期性交替变化的生物钟极限环。采用的是耗散结构论和协同论研究复杂自组织系统的一般方法。脑电快波一慢波振幅动力学方程的稳定性分析及脑电生物钟极限环显示的特性,在心理调控方面有广泛的应用价值和理论意义。 相似文献
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运用生物钟规律 提高教育教学效率 总被引：1，自引：0，他引：1
吕吉 《阜阳师范学院学报(社会科学版)》2004,(3):111-112
生物钟又叫生物节律或生物节奏 ,人体生物钟与人的心理有着密切联系 ,并且有规律地制约着人的行为。认识和掌握这种规律 ,有助于我们更好地指导自己的工作、学习和生活 ,以便扬长避短、趋利避害 相似文献
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Over the series of articles on circadian rhythms, we saw that living organisms exhibit daily rhythms in multiple behaviours and physiological processes. Although some rhythms may be passive responses to 24 h environmental cycles, many are regulated by endogenous-rhythmgenerating machinery called circadian clocks. We have introduced the concept of circadian clocks, their organization and the underlying molecular mechanisms. In this article, we will dwell upon one of the most fundamental questions pertaining to circadian clocks, ‘Why do we have them?’. The aim of this article is not to provide answers, but to discuss the efforts and strategies used to address this question and critically evaluate explanations proposed till date. 相似文献
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范继军 《河南科技学院学报》2006,34(1):123-125
本文从亚健康概念的提出以及亚健康状态的身体症状，分析造成人体亚健康状态的原因。过度疲劳造成的精力，体力透支，人的自然衰老，现代身心疾病，如心脑血管疾病，肿瘤等疾病的前期，人体生物周期中的低潮时期，剧烈运动导致的亚健康状态。我国的民族传统体育所具有的预防疾病、延年益寿的独特功能对人体亚健康状态有很好的治疗作用。本文并提出了中老年人参加健身运动应掌握适宜的运动负荷以及如何控制运动强度的方法。 相似文献
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Living organisms ranging from bacteria to human beings exhibit 24-h rhythms in various behaviours and physiological processes. Matching of the period of such rhythms with that of the daily environmental cycles gives an impression that they are mere passive responses to environmental changes. Here, we discuss the change in our perception about daily biological rhythms, from their identity as rhythmic phenomena occurring as passive response to environmental changes, to the biological clocks. This is the first article in a series of articles on circadian rhythms which will cover discussion on the genetic and molecular basis, circadian organization and its adaptive significance. 相似文献
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太阳能光伏发电研究现状与发展前景探讨 总被引：1，自引：0，他引：1
黄亚平 《广东白云职业技术学院广州白云工商高级技工学校学报》2007,14(2):113-117
太阳能光伏发电是利用光伏效应把太阳光能直接转换成电能的新能源技术。光伏发电对于人类解决能源危机和保护人类生存环境具有重大意义。目前世界各国竞相研究和发展太阳能光伏发电技术，现已取得较大进展。太阳能光伏发电在我国处于起步阶段，我国太阳能资源丰富，太阳能光伏发电在我国有很大发展前景。 相似文献
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植物细胞有丝分裂活动是有节律性的，受生物钟的制约。观察植物细胞的有丝分裂，常用的实验材料是洋葱根尖。在不同的时间剪下的洋葱根尖，实验的效果不一样。用不同浓度的龙胆紫染色液染色装片。实验的效果也不相同。植物细胞有丝分裂除受生物钟制约外，与环境温度也密切相关。 相似文献
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Joseph Klein 《Assessment in Education: Principles, Policy & Practice》2017,24(4):474-488
The purpose of the research is to investigate the behaviour of school personnel under two assessment-reporting conditions and school functioning when faced with the choice of excelling in high-stakes tests or catering to local educational needs. The functioning of 60 schools was compared in terms of their preparation for high-risk external tests and for low-stakes tests, of the same level of difficulty. The study examined the practices of school principals, subject coordinators and teachers, communication with parents and the ethical behaviour of the school staff. In all the comparative measures, many more school resources were invested in preparation for high-stakes tests than for internal tests. This investment came at the expense of formal and informal cutbacks in studies for non-test subjects. A clearer, more comprehensive analytical picture of the behaviour of school personnel is obtained about differences in school functioning when external and internal tests are administered. 相似文献