不规则件优化排样的小生境遗传模拟退火算法

提出一种基于小生境遗传模拟退火算法求解不规则件排样问题的方法。该方法首先充分考虑不规则形状零件自身的形状特征,采用组合矩形包络算法将二维不规则零件的排样问题转化为矩形件的排样问题,克服了以往简单采用最小包络矩形代替零件排样存在空白区域,从而导致材料可能发生的利用率过低问题;然后利用遗传模拟退火算法及小生境技术相结合,寻找排样件在排样时的最优次序及各自的旋转角度;最后用"最低水平线与填充算法相结合"策略的启发式排样算法实现自动排样。实例表明了该算法的有效性和实用性。     

区域旅游规划中旅游资源集合区生态位的研究

旅游资源单体的结合与分散直接决定着区域旅游规划的定位。本文剖析旅游资源实体聚合与分散的特征,诠释了旅游资源集合区的内涵与外延,运用生态位理论探讨了旅游资源集合区在区域旅游规划中的地位和作用,并以浙江省为例对区域旅游规划中旅游资源集合区的生态位进行了研究,以期为区域旅游规划中对旅游资源的多角度认识提供参考。     

Diet and trophic niche space and overlap of Lake Ontario salmonid species using stable isotopes and stomach contents

Lake Ontario supports a diversity of native and non-native salmonids which are managed largely through stocking practices. Ecological changes (e.g., invasive species) altering the food web structure accompanied with shifts in prey abundance, necessitate understanding the trophic niches of Lake Ontario salmonids to aid in management. The objectives of this study were to quantify salmonid (5 species) trophic niches and dietary proportions using stable isotope ratios (δ¹³C and δ¹⁵N) of a large sample set (adult fish (>300?mm; n?=?672) and key offshore prey (5 species, n?=?2037)) collected across Lake Ontario in 2013. Estimates of prey based on stable isotope ratios were similar to stomach contents. Based on stable isotope ratios, non-native prey dominated salmonid diet; in particular alewife (Alosa pseudoharengus) constituted the majority (0.31 to 0.93) of all salmonid diets, and round goby (Neogobius melanostomus) contributed 0.26 and 0.19 of brown trout (Salmo trutta) and lake trout (Salvelinus namaycush) diets, respectively. Trophic niche overlap was high between all salmonids, except lake trout. The largest trophic niche overlap occurred between Chinook (Oncorhynchus tshawytscha), coho (Oncorhynchus kisutch), and Atlantic salmon (Salmo salar), and their reliance on alewife infers a strong pelagic foraging strategy. Lake, brown and rainbow (Oncorhynchus mykiss) trout had larger and/or more distinct trophic niches indicative of a more variable diet across individuals and utilizing different foraging strategies and/or habitats. Overall, Lake Ontario salmonids maintained a high reliance on alewife, and their potential for plasticity in diet provides important information to management regarding population sustainability.     

An integrated approach to untangling mediated connectedness with online and mobile media

With the growth and convergence of mobile and social computing technology, mobile media are accorded new social meaning manifested in different aspects of our everyday life. This paper employs multiple theoretical frameworks—including the theory of the niche, the framework of media repertoires, and the communication infrastructure model—to examine individual-technology relationship as manifested through media repertoires and media connectedness. It argues that individuals tend to construct a set of media options and build connectedness with media technologies by engaging in a wide scope of activities through these media. In turn, this media repertoire and media connectedness may facilitate the performance of social and cultural practices in the public space. To investigate this conceptualization empirically, this study conducted a secondary analysis of data collected by the Pew Research Center in the United States. The results showed that multidimensional use of mobile apps was predicted by multidimensional Internet use, along with the scope of regular apps used and monetary investment by users. Additionally, multidimensional Internet use and the use of media repertoires consisting of mobile media and social media for socio-cultural activities facilitate public socio-cultural engagement. These results bring to light a new way of understanding how humans appropriate multiple types of technologies for activities in everyday life.     

Applications of scaffolds: Tools for enhancing the immunomodulation of mesenchymal stromal cells

Exogenously delivered mesenchymal stromal cells (MSCs) are therapeutically beneficial owing to their paracrine effect; they secrete various cytokines, nucleic acids, and proteins. Multiple bioengineering techniques can help MSC cultures to release secretomes by providing stem cell niche-like conditions (both structurally and functionally). Various scaffolds mimic the natural extracellular matrix (ECM) using both natural and synthetic polymers, providing favorable environments for MSC proliferation and differentiation. Depending on material properties, either topographically or elastically structured scaffolds can be fabricated. Three-dimensional scaffolds have tunable substrate rigidities and structures, aiding MSC cultivation. Decellularized ECM-derived hydrogels are similar to the natural ECM, thus improving the paracrine effects of MSCs. Here, we discuss recent research on the application of scaffolds to maximize the immunomodulatory function of MSCs.     

Emergence and the Forms of Metabolism

Earlier this year, Michael Weinstock published a seminal book, The Architecture of Emergence: The Evolution of Form in Nature and Civilisation, which challenges established cultural and architectural histories. The conventional worldview is expanded by placing human development alongside ecological development: the history of cultural evolution and the production of cities are set in the context of processes and forms of the natural world. As well as providing a far-reaching thesis, Weinstock's book gives lucid and accessible explanations of the complex systems of the physical world. In this abridged extract from Chapter 5, Weinstock explains the dynamics of individual and collective metabolisms from which intelligence and social and spatial orders emerge. Copyright © 2010 John Wiley & Sons, Ltd.     

基于遗传算法的火炮总体参数动力学优化

为提高火炮射击精度,寻找最佳的总体参数,本文利用小生境遗传算法,实现了与ADAMS软件联合进行火炮总体参数动力学优化设计。结合某火炮,对上述方法进行了计算,计算结果表明：优化后的炮口扰动值比优化前明显降低;小生境遗传算法一次可以搜索出多个有效方案,给火炮总体布置带来更大灵活性。     

小生境遗传算法在孔隙介质反演中的应用研究

为加快寻找地下复杂介质中的油气，针对含单相饱和流体的孔隙介质，综合了等效孔隙介质理论、Radon变换以及小生境遗传算法等，将接收信号与遗传群体相联系，引入了最小二乘原理和小生境迭代，形成了基于等效孔隙介质模型与地震CT技术的小生境多参数反演算法。理论分析与反演结果表明，该方法能够有效避开波动方程求解的复杂性，精度高、求解方便，具有一定的实用价值，能有效解决井间地层成像问题。图2表2参16     

Strategic niche management for biofuels: Analysing past experiments for developing new biofuel policies

Biofuels have gained a lot of attention since the implementation of the 2003 European Directive on biofuels. In the Netherlands the contribution of biofuels is still very limited despite several experiments in the past. This article aims to contribute to the development of successful policies for stimulating biofuels by analysing three experiments in depth. The approach of strategic niche management (SNM) is used to explain success and failure of these projects. Based on the analysis as well as recent innovation literature we develop a list of guidelines that is important to consider when developing biofuel policies.     

Optimization of Rolling Force Distribution Based on Niche Genetic Algorithm in Continuous Hot Rolling Mills

Based on the niche genetic algorithm, the intelligent and optimizing model for the rolling force distribution in hot strip mills was put forward. The research showed that the model had many advantages such as fast searching speed, high calculating pre- cision and suiting for on-line calculation. A good strip shape could be achieved by using the model and it is appropriate and practica-ble for rolling producing.