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Motivated by the work in [1] of Abualrub and Siap (2009), we investigate (1+λu)-constacyclic codes over Fp[u]/〈um〉 of an arbitrary length, where λ is a nonzero element of Fp. We find the generator polynomials of (1+λu)-constacyclic codes over Fp[u]/〈um〉, and determine the number of (1+λu)-constacyclic codes over Fp[u]/〈um〉 for a given length, as well as the number of codewords in each such code. Some optimal linear codes over F3 and F5 are constructed from (1+λu)-constacyclic codes over Fp+uFp under a Gray map. 相似文献
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在核心期刊的研究中 ,核心区与非核心区之间有没有明显的界线及如何划分是一个非常实际的问题 ,而且多年来这个问题一直没有得到很好的解决。在不断探索中 ,人们为了追求理性 ,于是把R(n) -n曲线是否连续来作为判定的依据 ,认为如果曲线连续 ,核心区与非核心区之间就没有明显的界线 ,否则就存在明显的界线。《中文核心期刊要目总览》2 0 0 0年版在研究报告中利用数学方法证明了R(n)-n曲线是连续的 ,不存在任何突变点 ,既而断定核心区与非核心区之间不存在明显的界线[1] 。人们对这一结论已经没有什么怀疑了 ,因为无论是核心区还是核心期刊… 相似文献
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Biofuel production has recently attracted much attention. Some anticipate substantial social and environmental benefits, while at the same time expecting sound profitability for investors. Others are doubtful, envisaging large trade-offs between the pursuit of social, environmental and economic objectives, particularly in poor countries in the tropics. The paper explores these issues in Tanzania, which has been an African forerunner in the cultivation of a bio-oil shrub called Jatropha curcas L. We trace how isolated Jatropha biofuel experiments developed since early 2005 towards a sectoral production and innovation system, and we investigate to what extent that system has been capable of developing and maintaining sustainable practices and producing sustainable outcomes. The application of evolutionary innovation theory allows us to view the developments in the sector as a result of evolutionary variation and selection on the one hand, and revolutionary contestation between different coalitions of stakeholders on the other. Both these processes constitute significant engines of change. While variation and selection are driven predominantly by localised technical and agronomic learning, the conflict-driven dynamics are highly globalised and occur primarily as a result of reflexive learning about problematic sustainability impacts. The sector is found to have moved some way towards a full sectoral innovation and production system, but it is impossible to predict whether a viable sector with a strong “triple bottom line” orientation will ultimate emerge, since many issues surrounding the social, environmental and financial sustainability still remain unresolved, especially relating to local and global governance. 相似文献
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本文对电工学教材中比较常见的Y—Δ起动控制电路工作的可靠性进行了分析,并阐述了提高Y—Δ起动控制电路工作可靠性的方法。 相似文献
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This paper concentrates on computing the stabilizing region
of PDμ controller for fractional order system with general interval uncertainties and an interval delay. The stabilizing region means the complete/approximate set of PDμ controllers that stabilize the given closed-loop control system. General interval uncertainties refer to both coefficients and orders of the fractional system suffer from interval uncertainties. Interval delay indicates that the delay also vary in a specified interval.Firstly, a method is presented to calculate the stabilizing region for general interval fractional system with an interval
time-constant delay. Based on a novel mapping function and the concept of critical controller parameters, the stabilizing region can be determined numerically. Secondly, the stabilizing region computation problem for general interval fractional system with an interval time-varyingdelay is considered. By applying a revised small-gain theorem, the stabilizing region can be calculated like the time-constant delay case. Thirdly, two alternative methods are proposed to improve the computational efficiency of stabilizing region calculation. Both methods can reduce the number of polynomials which are used to determine the stabilizing region. Examples are followed to illustrate the proposed results. 相似文献
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何荣利 《中国科技期刊研究》2007,18(5)
王嘉凌等同志在"就《中文核心期刊评价指标权重的分析与思考》一文与何荣利先生商榷"的文章中认为:"由于在相同文献密度差ΔM的情况下存在文献量的差别,因此,用文献密度差ΔM不能比较核心效应的强弱,应该用文献聚散度ΔMn比较较为恰当".王文引进相对值ΔMn的基本思路是对的,但测定结果与核心期刊的基本特征存在不相符合之处,而且出现许多相同的结果,不便于核心效应强弱的比较.相比之下,用文献密度差ΔM比较核心效应更加直观可见. 相似文献
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《中国科技信息》2006,(6)
美国微芯科技(Microchip)低功率、高解像度Δ-Σ(Delta-Sigma)ADC系列再添新品,MCP3550据称是目前市场上功率最低、体积最小兼配备高于16位解像度的ADC。新款的22位器件采用八引脚MSOP封装(3.1×3.1×1.18mm),可在低至120μA的典型电流下操作。此外,新器件可抑制50Hz和60Hz行频的噪音,为消费性、工业、电池供电及便携式设备提供高度精准的测量。MCP3550ADC的积分非线性(INL)典型值为±2ppm,在5V电压下最大功耗为0.6mW,最低输出噪音则为2.5微伏特均方根(RMS)。新器件可抑制50和60Hz行频下高于120分贝的噪音,使测量工作不受来自… 相似文献
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在科学研究活动社会化以及全球经济一体化的背景下,科学研究活动需要进一步提高效率和透明度。资助科学研究活动的政府和企业等机构也越来越多地要求研究机构证明科研活动是按照最高的标准完成的。充分考虑到目的适用性,在科研活动中采用质量保证方法不仅能够保持科研活动本身的创造力和灵活性,还可以提高科研工作的效率,促进科学技术创新。 相似文献
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本文首先论述了工业园区产业生态网络的系统构成和网络特性,并借鉴网络组织绩效评价的基本框架提出园区产业生态网络的绩效可以从网络适应性、网络增值性、网络开放性与网络和谐性四个方面进行测度。同时,运用问卷调查与实证数据分析相结合的方法,研究了测度工业园区产业生态网络的指标体系和指标权重,力图从园区环境、经济和社会协调发展的视角结构化的评估工业园区产业生态网络的绩效。 相似文献