基于圩田缓冲系统的自适应性城市设计方法论——武汉新区四新地区概念规划与核心区城市设计

以武汉新区四新地区概念规划与核心区城市设计优胜方案为案例,对正统物质规划中的"非水既土,非土既水"的刚性水地关系提出挑战。从分析现有问题入手,通过引入荷兰圩田缓冲系统,利用多样化规划手段、产业结构群、土地利用模式来重构一种新型的、基于多样选择的、可适应性的水地关系。所提倡的自适应性设计方法论将一部分水地界面形态交给圩田缓冲系统去自适应性地生成,而非由规划师一锤定音式地按单一形式预先在规划图纸上完全界定。这种设计新思维引入自适应性作为设计手段之一来防止人类正统物质性规划方法对现存自然生态系统的同化与破坏。进而重构"人—水—地"之间的可持续发展关系,使人、城市空间、景观与自然生态系统协调发展,共同演进。     

基于实测数据的风电场风速-功率模型的研究

建立准确的风电场模型是风电接入系统相关研究的基础。首先通过对某双馈风电机组的标准功率特性曲线和实测风速-功率散点图进行对比,针对它们之间的差异问题,建立基于实测运行数据的风电机组风速-功率模型。其次,针对地形复杂、机组排列不规则的大型风电场风速差异性问题,利用K-means聚类算法对风电场内所有风电机组按实测风速数据进行聚类划分,建立了整个风电场的等效风速模型,进而给出了基于实测运行数据的风电场风速-功率模型。然后,以某实际风电场为例,对该风电场内的风电机组按风速进行K-means聚类划分,结果显示该划分结果与简单按地理位置的机群划分结果有明显差异。最后,对传统的风速-功率模型和所提出的风速-功率模型输出结果进行比较,结果证明所提出的模型相对于传统模型而言,准确性有了较大的提高。     

New opportunities to understand heterogeneous catalysis processes on nanoscale bimetallic particles through synchrotron radiation and theoretical studies

New advances in theoretical background and recent experimental results concerning nanoscale bimetallic clusters are presented. From theoretical point of view, we will show how both the relaxation of the intermetallic distances and the chemical local ordering can be predicted from the electronic structure. Here, we compare these predictions at thermodynamical equilibrium to a review of recent results obtained using XAS for bimetallic systems Pt–M where M is a 4d transition metal. Even though the distribution of the two species inside the cluster can be affected by preparation parameters, such as, the nature of the precursor, it appears that these theoretical calculations are a valuable starting point for the study of such entities.     

Electronic properties of chemically produced silver clusters: grain morphology studies

Abstract

The electronic properties of silver clusters formed on the surface of reduction- sensitized octahedral and cubic AgBr emulsions were studied. Prior to sensitization with dimethylamineborane, SnCl₂ or high pH, these emulsions had the same efficiency. The results suggest that the octahedral emulsion has more potential to achieve a higher maximum speed increase. This difference may be due to fewer available sites for silver cluster formation on cubic surfaces. Gelatin concentration studies showed that the gelatin and/or impurities do play a role in silver cluster formation by high pH treatment. The precise role of OH^? is uncertain.     

Theoretical studies of CO hydrogenation to methanol over Cu, Pd, and Pt metals

Theoretical studies of CO hydrogenation to methanol over Cu, Pd, and Pt metals have been carried out using a quasi‐relativistic density‐functional method. The metal surface is simulated by a M₁₀ cluster model. Reaction energies for the elementary steps involved are determined. The activation energies are estimated by the analytic BOC‐MP formula. The results support that these metals are active in CO hydrogenation to methanol. The rate‐determining steps are shown to be different for the metals. The highest activation energies of reaction on the metals fall in the order Cu < Pd < Pt, which corresponds to the order of the catalytic activities of the metals in CO hydrogenation. This revised version was published online in July 2006 with corrections to the Cover Date.     

A novel 3D network coordination polymer consisting of paddlewheel Co3 clusters connected by PO4 and 4-pyridinecarboxylate

The synthesis, structural characterization and preliminary magnetic studies of a novel coordination polymer with paddlewheel Co₃ clusters are reported firstly. In the polymer, Co₃ clusters are covalently linked through PO₄ tetrahedra and 4-pyridinecarboxylate (4-pya) ligands into interpenetrated three-dimensional network.     

Au8 cluster adsorption on Si(100):2 × 1 asymmetric surface studied by a first principles calculation

In this work, we investigate the adsorption of Au₈ cluster onto H-terminated Si(100):2 × 1 asymmetric surface by density functional theory within local density and generalized gradient approximations. We study the site-dependent shape of Au₈ cluster, adsorption energies, band structures and the corresponding charge distribution. We show that the electronic properties of the cluster and substrate complex change with the location of the cluster on the surface.     

Supported gold clusters and cluster-based nanomaterials: characterization, stability and growth studies by in situ GISAXS under vacuum conditions and in the presence of hydrogen

This contribution is devoted to study of the thermal stability and growth of gold nanoparticles supported on SiO₂/Si(111) and Al₂O₃/SiO₂/Si(111) as a function of initial cluster size, support material and level of surface coverage. Experimental evidence for “flipping” of two dimensional cluster structures from vertical orientation to horizontal on the support is presented.     

Structures and stabilities of C36-rings

C₃₆-rings with D_nh symmetries have been investigated using the semi-empirical molecular orbital method (AM1). The ring structures are beneficial to the stability of the C₃₆ systems. An analysis of several factors, such as the change in strain energies due to the distortion of C₃₆ cages, the type of the bonded carbon atoms, the size of retained aromatic domains and the shared pentagon-pentagon double bonds, is given for their contributions to stabilities of the C₃₆-rings. The electronic properties are also discussed and compared with those of C₆₀-rings.     

Comparing a Pharmaceutical and an Agro-food Bioregion: On the Importance of Knowledge Bases for Socio-spatial Patterns of Innovation

The aim of this paper is to compare the socio-spatial patterns of innovation and knowledge linkages of a biopharmaceutical and an agro-food biotech cluster. Dissimilarities can be expected based on differences in terms of historical technological regimes and sectoral innovation system dynamics between the agro-food and pharmaceutical industries in general and particularly the distinctive analytical (science-based) knowledge base of biopharmaceuticals in contrast with the more synthetic (engineering-based) knowledge base of agro-food biotechnology. Drawing on bibliometric data and case material the study compares two representative bioregions: a biopharmaceutical cluster in Scania, Sweden and an agro-food biotech cluster in Saskatoon, Canada. The empirical study supports the theoretical expectations and shows that knowledge dynamics in the agro-food cluster are more localized than in the biopharmaceuticals cluster. It is important, however, to acknowledge that these differences are relative. Both sectors display local and non-local patterns of collaboration following the general pattern for biotechnology.