Fractional multiple birth-death processes with birth probabilities λi(Δt)+o((Δt))

The usual model for (Poissonian) linear birth-death processes is extended to multiple birth-death processes with fractional birth probabilities in the form λ_i(Δt)^α+o((Δt)^α, 0<α<1. The probability generating function for the time dependent population size is provided by a fractional partial differential equation. The solution of the latter is obtained and comparison with the usual model is made. The probability of ultimate extinction is obtained. One considers the special case of fractional Poissonian processes with individual arrivals only, and then one outlines basic results for continuous processes defined by fractional Poissonian noises. The key is the Taylor’s series of fractional order f(x+h)=E_α(h^αD_x^α)f(x), where E_α(·) is the Mittag-Leffler function, and D_x^α is the modified Riemann-Liouville fractional derivative, as previously introduced by the author.     

The Jatropha biofuels sector in Tanzania 2005-2009: Evolution towards sustainability?

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.     

Stabilizing region of PDμ controller for fractional order system with general interval uncertainties and an interval delay

This paper concentrates on computing the stabilizing region of PD^μ controller for fractional order system with general interval uncertainties and an interval delay. The stabilizing region means the complete/approximate set of PD^μ 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.     

PB科学研究的质量保证问题研究/FONT/B/P PSTRONG/FONT/STRONG /P

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。     

自然/人/机器

正自然与人类以及科技是千年大事。一切都需要重新审视、重新理解、重新梳理与建构。个体的重要性下降,科技和群体的重要性上升。今天讨论一下关于人类在自然界中的位置以及人与自然和机器之间的关系变化。人与自然的关系关于人与自然的关系,在本世纪50年代以前,有两种基本观点:一是人类中心论,它重视、强调人与动物的区别和人与人之间的关     

国内外专利研究的比较分析 /FONT /P /FONT /P

摘要：本研究结合传统的统计方法、共被引分析方法和最新的可视化手段,对国内和国际专利研究论文的学科分布情况、共被引网络以及研究前沿等进行了展示和比较。对国际专利研究的学科布局、近期发展态势、研究现状和前沿领域的转移等进行挖掘,得出利用专利数据进行定量研究以探究专利的经济意义和战略价值,是近年来国际专利研究的主要热点。指出国内专利研究中存在的不足和未来的发展方向。     

工业园区产业生态网络绩效测度研究 /FONT /P /FONT /P

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。