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磁致伸缩位移传感器是一种测量精度高,测量位移大的新型位移传感器.传感器设计涉及多学科交叉,难以建立统一数学模型.以FeGa材料作为磁致伸缩位移传感器的核心波导丝,建立了波导丝材料磁致伸缩弹性波振动模型,波导丝磁机耦合模型和信号检测模型;同时分析了弹性波信号的受限因素,信号衰减特性.在数学模型基础上,搭建磁致伸缩位移传感器系统,设计了扭转波信号检测电路.实验结果表明信号的输出随着传感距离的增加而减小,该模型对大位移磁致伸缩传感器研究有积极意义. 相似文献
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光纤是光纤陀螺的核心器件之一。光纤的性能参数直接决定光纤陀螺的性能。常规硅芯光纤制造工艺比较成熟,但受限于物理条件,"克尔效应"、"瑞利背向散射效应"、"法拉第效应"和"舒珀效应"影响比较大。近年来,基于光子带隙效应的导光机制与传输特性制成的在空气中传输光线的空芯光子带隙光纤逐渐应用在光纤陀螺制造中。介绍空芯光子带隙光纤的性能特点,尤其是相比常规硅芯光纤的优势;空芯光子带隙光纤的技术发展潜力;展望其在光纤陀螺中的应用前景。 相似文献
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针对拉曼散射是一种弱散射,同时由于空心光子晶体光纤(HC—PCF)能显著增强光与填充介质之间的相互作用,提出将HC—PCF应用到拉曼光谱仪中,利用平面波展开法对HC—PCF的光子带隙与场分布进行模拟分析,探讨了HC—PCF的参数对拉曼散射强度的影响。通过理论研究发现光子晶体光纤可根据实际应用的需要,通过改变光纤的周期结构或包层气孔之间的间距来改变光子带隙,从而可传输不同波段的光。结果表明了HC—PCF在拉曼光谱仪中应用的可行性,为拉曼光谱仪在分子结构检测与分析提供了新的技术方法,也为HC—PCF的应用和研究开拓了广阔前景。 相似文献
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傅海卿 《电子制作.电脑维护与应用》2015,(11)
本文所提出的新型的全光纤甲烷检测系统是依托空芯光子带隙光纤作为检测气体传感的探头,利用谐波检测技术处理信号的一种甲烷检测方式。旨在正确分析甲烷气体在空芯光子带隙光纤中的扩散特性,从而对传感气室实现优化设计。另外,研究通过实际的试验成果证实利用空芯光子带隙光纤进行甲烷检测具有一定的可行性。 相似文献
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介绍了一种新型光子晶体压力传感器,利用压力使光子晶体带隙的变化特性制作压力传感器,提出了通过测量透射光的变化来测量压力的检测方法。结果表明:传感器的测量范围和灵敏度与构成光子晶体的材料特性有关,材料弹性模量小时,灵敏度高;2种材料的弹性模量和泊松比相差大时,测量范围小。该传感器体积小、重量轻。 相似文献
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利用三轴线性霍尔传感器MLX90393制作磁记忆检测探头,基于Arduino硬件开发平台研制金属磁记忆检测系统,以30CrMo材料试件为试验对象,在静载拉伸作用下开展金属磁记忆试验研究,分析磁记忆信号变化规律以及磁记忆信号梯度值与拉伸载荷之间的变化特征.实验结果表明,拉伸过程中试件表面的磁记忆信号切向分量梯度最大值在拉伸载荷达到16 kN时开始明显变化,在23 kN之后急剧增大到0.0425;法向分量梯度最大值在拉伸载荷达到23 kN之后急剧增大到0.55.本系统为铁磁性材料中应力集中的判定和测量提供了一种有效的检测方法. 相似文献
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European Community policy and the market 总被引:1,自引:0,他引:1
C. Lloyd 《Journal of Computer Assisted Learning》1993,9(2):86-91
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven. 相似文献
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融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。 相似文献
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David Poole 《Computational Intelligence》1989,5(2):97-110
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given. 相似文献
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Watts S. Humphrey 《Annals of Software Engineering》2002,14(1-4):39-72
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical. 相似文献
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基于复小波噪声方差显著修正的SAR图像去噪 总被引:4,自引:1,他引:3
提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。 相似文献
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R. NOSS 《Journal of Computer Assisted Learning》1987,3(1):2-12
Abstract This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development. 相似文献
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C. Xiang 《控制理论与应用(英文版)》2014,12(3):217-217
正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where 相似文献
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《浙江大学学报:C卷英文版》2014,(7)
正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere. 相似文献
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Alan V. Di Vittorio 《Remote sensing of environment》2009,113(9):1948-2750
The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm2, BIAS = 0.143 µg/cm2, RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm2, BIAS = − 0.992 µg/cm2, RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm2, BIAS = − 2.12 µg/cm2, RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data. 相似文献
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Philip Marks 《Cryptologia》2018,42(1):1-80
This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G). 相似文献