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61.
62.
以山西省河津市小梁乡为代表,研究了因建筑业的发展壮大而产生的社会经济空心化现象,分析了其形成原因,并提出了解决措施,以期引起大家对这一社会经济现象的关注,开展更深层次的研究。 相似文献
63.
李彩虹 《南京工业职业技术学院学报》2008,8(2):1-3
根据PET薄膜的特点和高分子熔融态流动理论,分析了挤出回收用螺杆的各段结构,及螺杆参数选择,设计出大长径比、深槽、双排气、高效专用螺杆。 相似文献
64.
We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores. 相似文献
65.
66.
对称配筋小偏心受压构件的截面设计 总被引:4,自引:1,他引:3
对小偏心受压构件在对称配筋情况下的截面配筋计算,提出用最佳一次逼近多项式简化基本公式,直接按二次方程求解ξ的近似方法,具有精度高,相对误差小,计算方便等优点,可供工程设计人员参考。 相似文献
67.
Chris Harty 《Building Research & Information》2005,33(6):512-522
An alternative approach to understanding innovation is made using two intersecting ideas. The first is that successful innovation requires consideration of the social and organizational contexts in which it is located. The complex context of construction work is characterized by inter-organizational collaboration, a project-based approach and power distributed amongst collaborating organizations. The second is that innovations can be divided into two modes: 'bounded', where the implications of innovation are restricted within a single, coherent sphere of influence, and 'unbounded', where the effects of implementation spill over beyond this. Bounded innovations are adequately explained within the construction literature. However, less discussed are unbounded innovations, where many firms' collaboration is required for successful implementation, even though many innovations can be considered unbounded within construction's inter-organizational context. It is argued that unbounded innovations require an approach to understand and facilitate the interactions both within a range of actors and between the actors and technological artefacts. The insights from a sociology of technology approach can be applied to the multiplicity of negotiations and alignments that constitute the implementation of unbounded innovation. The utility of concepts from the sociology of technology, including 'system building' and 'heterogeneous engineering', is demonstrated by applying them to an empirical study of an unbounded innovation on a major construction project (the new terminal at Heathrow Airport, London, UK). This study suggests that 'system building' contains outcomes that are not only transformations of practices, processes and systems, but also the potential transformation of technologies themselves. 相似文献
68.
Non-pinched, minimum energy solutions are important class of distillation designs that offer the potential advantage of a better trade-off between capital investment and operating costs. In this paper, two important tasks associated with non-pinched distillation designs are studied. Thus the novel contributions of this work to the literature are
- (1) A comprehensive methodology for finding non-pinched minimum energy designs.
- (2) Understanding of the reasons for the existence of non-pinched distillation designs.
69.
Jennifer Spenader 《Journal of Logic, Language and Information》2003,12(3):351-368
There are three ways to refer to a fact from the complement of afactive verb: (1) Via abstract object anaphoric reference, or, witha full sentential complement that will be interpreted either (2) asa bound presupposition or (3) as triggering a presupposition of afact that will have to be accommodated. Spoken corpus examplesreveal that these three possibilities differ in relation to thetype of information they tend to contribute, and this has twoeffects. First, the information status of the fact and its role inthe discourse seem to affect the preference for one constructionover another in a particular context. Second, presupposed factivecomplements that need to be accommodated tend to be hearer-new andthe focus of the utterance, meaning that information structureseems to contribute to the felicity of accommodation ofpresupposed facts. 相似文献
70.
沸石孔结构对1-己烯异构化性能的影响 总被引:1,自引:0,他引:1
采用1-己烯为原料,对硅铝比相近、不同孔结构的沸石在脉冲微反装置上进行了评价试验,考察了FCC条件下沸石孔结构对烯烃异构化性能的影响。结果表明,大孔径的Y型沸石具有良好的异构化性能,异构化能力由强到弱的排列顺序为Y>β>ZRP>丝光沸石>镁碱沸石。 相似文献