气动端面行星运动式金刚石磨具的制作

对金刚石磨具的种类和现代磨削技术的特点进行讨论，阐述了一种气动端面行星运动式金刚石磨具的设计与制作.设计结果表明，使用该磨具加工的成品精度高，能满足车床工作要求.     

弧面凸轮的行星式磨削机理研究

磨削加工是弧面凸轮加工的一个重要工序,弧面凸轮的加工质量和精度与其密切相关。通过采用行星式磨削方 法和单侧面磨削原理,在行星式磨削装置中增加微进给机构,通过监测装置所反馈的数据,使得砂轮在磨削过程中可以 通过微进给机构增大砂轮的公转半径,实现砂轮的磨损补偿。弥补了行星式磨削方法不能在磨削时进行磨损补偿的缺 点,从而能够实现弧面凸轮的连续磨削,提高了弧面凸轮的磨削效率和磨削精度。     

Learning-based EM algorithm for normal-inverse Gaussian mixture model with application to extrasolar planets

Karlis and Santourian [14 D. Karlis and A. Santourian, Model-based clustering with non-elliptically contoured distribution, Stat. Comput. 19 (2009), pp. 73–83. doi: 10.1007/s11222-008-9072-0[Crossref], [Web of Science ®] , [Google Scholar]] proposed a model-based clustering algorithm, the expectation–maximization (EM) algorithm, to fit the mixture of multivariate normal-inverse Gaussian (NIG) distribution. However, the EM algorithm for the mixture of multivariate NIG requires a set of initial values to begin the iterative process, and the number of components has to be given a priori. In this paper, we present a learning-based EM algorithm: its aim is to overcome the aforementioned weaknesses of Karlis and Santourian's EM algorithm [14 D. Karlis and A. Santourian, Model-based clustering with non-elliptically contoured distribution, Stat. Comput. 19 (2009), pp. 73–83. doi: 10.1007/s11222-008-9072-0[Crossref], [Web of Science ®] , [Google Scholar]]. The proposed learning-based EM algorithm was first inspired by Yang et al. [24 M.-S. Yang, C.-Y. Lai, and C.-Y. Lin, A robust EM clustering algorithm for Gaussian mixture models, Pattern Recognit. 45 (2012), pp. 3950–3961. doi: 10.1016/j.patcog.2012.04.031[Crossref], [Web of Science ®] , [Google Scholar]]: the process of how they perform self-clustering was then simulated. Numerical experiments showed promising results compared to Karlis and Santourian's EM algorithm. Moreover, the methodology is applicable to the analysis of extrasolar planets. Our analysis provides an understanding of the clustering results in the ln?P?ln?M and ln?P?e spaces, where M is the planetary mass, P is the orbital period and e is orbital eccentricity. Our identified groups interpret two phenomena: (1) the characteristics of two clusters in ln?P?ln?M space might be related to the tidal and disc interactions (see [9 I.G. Jiang, W.H. Ip, and L.C. Yeh, On the fate of close-in extrasolar planets, Astrophys. J. 582 (2003), pp. 449–454. doi: 10.1086/344590[Crossref], [Web of Science ®] , [Google Scholar]]); and (2) there are two clusters in ln?P?e space.     

对托勒密地心模型的探究

地心模型是世界上第一个行星体系的模型,在天文学行星模型中是一个重要的概念.学习托勒密地心模型对于了解天文学有着不可或缺的重要地位.通过探究表明,地心模型有着严密的科学性和较强的实用性.     

哥白尼日心说体系的美学特征

本文从科学美的思想出发,讨论了地心说的丑,分析了日心说的简洁、和谐和数学等方面的美学特征。     

“人类世”视野下西方生态批评的拓展

"人类世"这一概念自21世纪初被提出以来,在西方诸多领域引起了广泛关注和热议,包括将环境、自然作为主要关注对象的生态批评。这一概念迫使研究西方生态批评的学者迅速做出反应,在反思人类对地球的地质影响之时,将学术研究的范围在时间和空间两个维度上延展:从作为研究主体的人到作为研究客体的环境,再到研究具体内容和方法,都在这个新概念的启发和推动下不断得到深化和拓展,包括建立地球意识、推动灾难故事和慢性暴力叙事等。     

从地方到全球到“全球地方”——斯科特·斯洛维克教授访谈

斯科特·斯洛维克以美国西部生态批评,尤其以美国西南部环境文学研究为例,就如何探寻环境文学中的地方和全球意义,如何扩大生态批评的研究范畴做了有意义的探讨,提出生态批评现阶段关于"地方"的看似矛盾的两个观点:地方意识和全球意识,倡导"生态世界主义",认为我们应该在特性与共性、地方与全球、人类与非人类之间寻求一个平衡,生态批评或者说环境文学研究就应该积极探寻这些关系的含义。     

Environmentally Responsible Happy Nation Index: Towards an Internationally Acceptable National Success Indicator

Amidst increasing attention to happiness studies by economists, the New Economics Foundation launched in July 2006 the Happy Planet Index (Marks et al. 2006). This is the ratio of the average happy life years (HLY) to the per capita ecological footprint of the country concerned. HLY is in turn the product of the average happiness (or life satisfaction) index and the life expectancy index. Some essential revisions to this index are proposed to reach an internationally acceptable national success indicator that aims positively at long and happy lives but negatively at the external costs of environmental disruption. Hopefully, this ‘environmentally responsible happy nation index’ will lead to some re-orientation of both the market and national governments towards something more fundamentally valuable.

行星意识与建设节约型社会的文化思考

21世纪,人类社会在进入了一个全新的发展时代的同时,也面临着如何解决人类文化发展与地球资源有限的矛盾和困境."行星意识"的提出要求我们要认识到地球是一个有限的生存时空,人类只有改变传统的思维方式和生产、生活方式,学会全球性思考,才能保护人类文化的延续.所以,进化出"行星意识"是人类在地球上生存发展的文化自觉.而中国关于建设节约型社会的提出恰恰表现了承担人类文化共同进步的"行星意识"和时代责任,说明节约不仅仅表现为物质上的不浪费和要求在经济运行中对资源、能源需求实行减量化,更重要的是节约体现了一种人类文化安全意识和对人类文化发展的终极关怀.